Hesperidin

Hesperidin is a flavanone glycoside named after the term 'Hesperidium', referring to citrus fruits which are the main source of hesperidin. Hesperidin and its aglycone are common dietary flavonoids due to being large compounds of citrus fruits (alongside naringenin) and especially the peels and pericarp,^[5] hesperidin has once been noted to comprise up to half of the flavonoid intake of Finland in surveys due to its prominence in the diet (at 28.3mg daily calculated as aglycones)^[6] and it could be argued that it is a traditional chinese medicine (perhaps alongside naringenin) since the dried peels of citrus have been used medicinally and referred to as Chimpi.^[7]

A classical term 'Citrin' or 'Vitamin P' is used to refer to a mixture of Hesperidin and Eriodictoyl (another flavonoid), which were initially thought to have vitamin-like properties by having wound healing properties and treating scurvy; this was later attributed to Vitamin C.^[8][9]

Hesperidin is the food-bound form of hesperitin, a bioflavonoid, and is one of the two molecules which were erronously called 'Vitamin P' in the past due to confusion with Vitamin C, it is found in many citrus products and is most well known for being concentrated in orange peels

Hesperidin can be found in (measured in aglycone equivalents, or in other words measuring hesperitin, unless otherwise specified):

• Commercial sweet orange (Citrus sinensis) juice products in the range of 12.7-15.9mg per 100mL^[10] and around 15.25+/-8.21mg/100g fresh fruit weight^[11][12]

• Sour orange (Usually Citrus aurantium, also refers to bergamia and myrtifolia) tend to be high in flavanones at 47mg/100g fresh weight, although they tend to be neohesperidin and naringin (narirutin) rather than hesperidin^[11] and contain barely any detectable hesperidin (at highest, 4.7µg/100g fruit weight)^[12][13]

• Tangerines or 'Mandarin Oranges' (Citrus reticulata) at 19.26+/-11.56mg/100g fresh fruit weight^[11][12][14] and the sundried peel (known as Chenpi in Traditional Chinese Medicine, or as Citri Reticulatae Pericarpum) contains hesperidin at 50-100mg/g^[15]

• Tangors, which are orange and tangerine hybrids, at 15.42+/-7.00mg/100g fresh fruit weight^[11][12][14]

• Tangelos, which are tangerine hybrids with grapefruit (Citrus paradisi) or pumello (Citrus grandis) at 4.21+/-2.93mg/100g fresh fruit weight (these fruits are highest in neohesperidin)^[11][12][13]

Hesperidin appears to be high in the common orange (Sweet orange or citrus sinensis) and is equally high if not a bit higher in tangerines and similarly high in their hybrid (the Tangor); making a hybrid of an orange with another citrus fruit (grapefruit or pomella) to make Tangelos reduces the hesperidin content to about a third or a quarter, while the sour orange (Citrus aurantium) contains no hesperidin

With some other sources that are not in the citrus family including:

• Boehmeria nivea (of the Urticaceae family) at 23.69mg/100g^[16]

• Valeriana wallichii (of the famiy Valerianaceae) at 6.2+/-0.25mg/g (0.6%) of a water extract^[17]

• Cyclopia subternata (Honeybush) at 0.504+/-0.495mg/g (range of 0.147–1.517mg/g) in the leaves and 1.559+/-0.289mg/g (range of 1.164–1.893mg/g) in the stems^[18][19]

• Codonopsis pilosula^[20]

• Schizonepeta tenuifolia^[21] at 12.0+/-0.4mg/g dried leaves^[22]

• Byrsonima crassifolia (of the family malpighiaceae) at 0.7mg/kg dry weight^[23]

Although thought to be practically exclusive to the citrus family, they are just the best source of hesperidin. It can be found in a variety of plants and supplements at lower levels, although it is not sure what roles it plays in these herbs

As a glycoside (with sugars), it has an aglycone (without sugars) flavanone known as hesperitin (5,7,3'-trihydroxy-4'-methoxyflavanone) and can also be referred to chemically as hesperitin-7-O-rutinoside (as the sugar it is bound to is rutinose) or hesperitin-7-O-rhamnosyl(1-6)glucoside (since a 'rutinose' sugar is 6-O-α-L-rhamnosyl-D-glucose, or simply a rhamnose sugar bound to a glucose).

The main molecule here is hesperitin, but it is found in foods as hesperidin which pretty much acts like a hesperitin prodrug (gives the body hesperitin, but is better than hesperitin itself at doing so due to various reasons). G-Hesperidin is another synthetic prodrug for hesperitin

Hesperitin is known as a flavanone (a subset of flavonoid or bioflavonoid) due to there not being a double bond between the 2 and 3 carbon on the A ring, which is the rightmost vertical line one the middle hexagon (a double bond would mean that two vertial lines were there). This lack of a double bond means that the B ring (hexagon not immediately bonded to another, furthest right on the pictures below) is more perpendicular to the other two rather than adjacent like shown in the 'standard depiction'.

Flavanones tends to be more linear than flavones since the double bond (which normally electrically pushes the B ring away from it) doesn't exist, so the B ring can float to a more linear position

Hesperitin (5,7,3'-trihydroxy-4'-methoxyflavanone) is most closely related to:

• Eriodictyol, where the methoxyl group is changed to another hydroxyl group (5,7,3',4'-tetrahydroxyflavanone)

• Isosakuranetin, where the hydroxyl group on the B ring is simply removed. Isosakuranetin is a flavanone, and the flavone version is Acacetin

• Diosmetin, where the flavanone is changed to a flavone by adding a double bond (5,7,3'-trihydroxy-4'-methoxyflavone); the rutinoside of diosmetin is diosmin

• Luteolin, which is a combination of the above two as eriodictyol becomes a flavone (5,7,3',4'-tetrahydroxyflavone)

• Naringenin (and its rutinoside Naringin or Narirutin) which replaces the methoxyl group on hesperidin with a hydroxyl similar to eriodictyol, but removes the other hydroxyl (5,7,4'-trihydroxyflavanone)

There are significant metabolic differences between diosmetin and hesperitin, such as in enzyme inhibition,^[24][25] which demonstrate that this structural change is more than sufficient to alter function. Furthermore, hesperitin and hesperidin can both exist as (S) and (R) isomers^[26] although this is commonly not investigated with supplementation (unlike some topics like Alpha-lipoic acid or L-Carnitine where the isomers are critical).

Hesperitin and Diosmetin are almost the same molecule, but only differ based on the position of the B ring since hesperitin is a flavanone and diosmetin is a flavone. Luteolin, a common flavonoid found in tomatoes, is structurally similar to diosmetin

One study has noted that following 5-7 days of sundrying, that the peels of tangerines have reached a concentration of 5-10% (50-100mg/g) hesperidin, with an average value of 67mg/g (6.7%).^[15] Assuming this quantity in the dried peel, a supplemental dose of 500mg hesperidin may be equivalent to approximately 5-10g of the dried peel.

Sundried tangerine peels, as per the traditional chinese medicinal usage, appear to confer a large enough dose of hesperidin that supplementation may not be required. It may be made more palatable by blending it into a shake

Glucosyl-hesperidin (G-Hesperidin) is a synthetically modified form of hesperidin where the aglycone (hesperitin) is not changed, but the diglycoside group has been modified into a triglycoside;^[27] this increases water solubility approximately 10,000-fold relative to hesperidin^[28] but ultimately it releases hesperidin (glycone) in the body after being metabolized by intestinal α-glucosidases^[27][28] and then hesperidin can release free hesperitin.

It does appear to have greater bioavailability, as one study using 1,500mg hesperitin equivalents of either G-Hesperidin or Hesperidin itself noted that standard heperidin peaked in the blood at 4µM and plateaued while G-hesperidin increased to three-fold higher levels and then steadily declined while remaining higher than 4µM at all time points for the next 24 hours.^[29]

G-Hesperidin is a highly water soluble prodrug for hesperidin, and at least for high oral doses of the supplement G-hesperidin appears to be a better prodrug than hesperidin at giving the body hesperitin

There is a synthetic variant of hesperidin known as hesperidin-7,3'-O-dimethylether (HDME) which is known to be more lipid soluble, and structurally speaking the lone hydroxyl group on the B ring is modified into another methoxyl group.^[30] HDME inhibits PDE1 (IC₅₀ value of 22.1+/-6.4μM), PDE3 (24.6+/-3.5μM), but inhibits PDE4 (3.0+/-0.9μM) with most selectivity^[30] where hesperidin normally doesn't inhibit any PDE isomer under 100μM^[30] and hesperitin inhibits PDE4 weaker (28.2+/-1.1µM) but does not influence other PDEs.^[31]

HDME is a more lipid soluble variant of hesperidin, and possesses phosphodiesterase inhibitory potential that is greater than hesperitin

Daflon is a brand name referring to a mixture of Diosmin (the chemically related flavone) and Hesperidin for the treatment of chronic venous insufficiency (CVI) and other venous system disorders such as restless leg syndrome, leg edema and varicose veins, and may also be recommended for acute hemorrhoidal attacks.^[2][3][4]

Daflon is a patented mixture of mostly the flavone glycoside Diosmin, but also has a 10% Hesperidin content

There is a traditional Japanese medicine (Kampo) known as Rikkunshito which is known as an appetite stimulant. It contains a variety of herbs including:^[32] 

• Rhizome of Atractylodis Lanceae (4g)

• Root of panax ginseng (4g)

• Vegetable (tuber) of pinellia ternata (4g)

• Hoelen (Wolfiporia extensa) at 4g

• Ziziphus jujuba fruits at 2g

• Licorice at 1g

• Ginger at 500mg

• Pericarp of Aurantii Nobilis (related to oranges) which contains both nobelitin and hesperidin at 2g

Hesperitin, isoliquirtigenin, and atractylodin are thought to be two major bioactives since they all stimulate ghrelin secretion independently.^[33][34]

Rikkunshito is a Kampo formulation for appetite stimulation and it is thought that hesperidin is a major bioactive since it works in isolation

There is a Korean formulation known as Pyeongwee-San extract (KMP6) for the treatment of inappetance, abdominal distension, borborygmus, diarrhea induced by gastric atony, gastric dilatation, and gastrointestinal catarrh; it contains:^[35]

• Atractylodes japonica (13.3g)

• Magnolia officinalis (10g)

• Citrus sunki (10g) conferring 5.67mg hesperidin per gram of KMP6

• Ziziphus jujuba (6.7g)

• Ginger (3.3g)

• Licorice (as uralensis; 3.3g)

KMP6 is a formulation for gastrointestinal distress and a lack of appetite, and hesperidin may be an active component

Hesperitin (100μM) has been noted to approximately half the ability of a ligand to associated with the TGFβ-II receptor and approximately halved the dimerization of these receptors (occurs when a ligand binds and is required for signalling^[36][37]),^[38] this reduced receptor and ligand association resulted in partial inhibition of Smad3 phosphorylation and nuclear translocation^[38] which is phosphorylated by this receptor.

Hesperitin appears to disrupt signalling through the TGF-β II receptor, but this has only been noted at concentrations much higher than occur in the body following supplementation

When investigating the inhibitory activities of hesperitin on phosphodiesterase (PDE) enzymes, it has been noted to have inhibitory actions on the PDE4 isomer (IC₅₀ of 28.2+/-1.1µM) and while this was weaker than other flavonoids such as luteolin (19.1+/-2.4µM), quercetin (9.9+/-2.5µM), genistein (9.5+/-1.9µM), and biochanin A (8.5+/-0.1µM) hesperitin was the most selective since its inhibitory actions on PDE1, PDE2, PDE3, and PDE5 were all above 100µM.^[31] Biochanin A was also ineffective on PDE5 and PDE3, but activated PDE1 (29.1+/-0.3µM) and PDE2 (27.9+/-4.1µM) thus being second most selective.^[31]

Hesperitin is moderately effective at inhibiting the PDE4 enzyme, but it is a highly selective PDE4 inhibitor. This may occur at a concentration that influences the intestinal tract but is unlikely to occur in the blood and peripheral tissue

While Hesperidin is a flavonoid diglycoside (two sugars), flavonoid monoglucosides can be absorbed in the small intestine following hydrolysis by lactase phloridzin hydrolases^[39][40] or cytosolic β-glucosidases.^[41][42] Rutinoside glycosides (rhamnose bound to glucose bound to the flavonoid) cannot be absorbed in this manner, and must proceed to the colon to be fermented prior to absorption^[43] similar to a few phenolic glycosides.^[44][45]

Hesperitin may be able to be absorbed in the small intestines, but hesperidin is a rutinoside (bound to rutin) and cannot be absorbed in the small intestine; it must pass onto the colon and be fermented by intestinal microflora to an alterante form that is more readily absorbed

Hesperitin (1% in cream) can be absorbed topically with peak absorption being seen in a solution with 10% PEG 400, reaching 16.9+/-7.8% absorption over 3.7 hours of measurement, with no significant influence on 12 hour absorption rates.^[46] It appears that 5% menthol in solution (main bioactive of peppermint oil) is able to enhance the topical absorption 9.3-fold over 12 hours.^[46]

Hesperitin appears to be absorbed topically in a manner that is significantly enhanced by menthol from peppermint

When consuming orange juice at 2-4 cups (0.5-1L), serum hesperitin concentrations reach up to 2μM^[47][48] whereas a juice with a low dose of hesperidin (32mg/L) with both naringenin and quercetin as well noted a low concentration of 180nM at peak.^[49] These low peak values are thought to be due to orange juice containing mostly hesperidin rather than hesperitin^[50] since flavonoids with a rutinoside (Rhamnosyl-glucoside) glycoside are known to have poorer absorption in the small intestines than either the aglycone or the glucoside conjugate;^[51] this is seen with quercetin (where the ruinoside called 'Rutin' is poorly absorbed)^[52][53] and also applies to hesperitin^[50] and treating orange juice with α-rhamnosidase might be able to increase absorption by yielding the aglycone (since it works with naringenin^[54]). That being said, these studies do note a delayed T_max and a time release effect of hesperidin supporting colonic release of hesperitin.

In subjects given either a high vegetable diet with minimal citrus products (132mg hesperitin via food products; one glass of orange juice and two citrus fruit halves) plasma hesperitin concentration can increase from 12.2nM at baseline up to 325nM.^[55]

When looking at food products (either citrus based products or food consumption), the hesperitin and hesperidin from these products can be absorbed but under normal dietary conditions blood levels reach the low to moderate nanomolar range and having a large amount of citrus products increases it up to the low micromolar range

Consumption of hesperidin (0.93-2.92mg/kg) via orange juice results in a C_max of 0.48-1.05μM at a T_max of 7.0-7.4 hours, conferring an AUC of 1.16-4.16μM/h,^[50] while the 7-O-glucoside at a dose equivalent to 0.93mg/kg once the weight of the glucose is account for (ie. 1.21mg/kg) has a faster peak T_max (36 minutes) reaching higher serum concentrations (2.60μM) and has a greater AUC (3.45μM/h).^[50] Other studies investigating the serum levels of hesperidin (via orange juice) have noted C_max values of 0.46–1.28μM at T_max values of 5.4–5.8 hours following ingestion of 110-220mg hesperidin^[48] and a C_max value of 2.2μM after hours, with a half-life of 2.2 hours.^[47]

Using higher doses of hesperidin can increase the plasma exposure with 1,500mg hesperitin equivalents (as either Hesperidin or G-Hesperidin) in 100mL of water noted that hesperidin plateaued at 4μM (around 8 hours) while G-Hesperidin peaked at 12μM (6-8 hours) and steadily declined, remaining higher than Hesperidin after 24 hours.^[29]

The T_max of hesperitin-7-O-glucoside (36 minutes^[50]) being significantly less relative to hesperitin-7-O-rutinoside (hesperidin; 5-7.4 hours^[50][48]) is due to glucosides being able to be absorbed in the small intestine while rutinosides need to reach the colon.

Hesperidin oral ingestion results in a circulating hesperitin content, and it appears to reach the low micromolar levels following oral ingestion of moderate to high doses; the absorption is somewhat delayed, and while it appears to increase blood values for up to a day after ingestion it reaches maximum values after abour 5-8 hours

Hesperidin has affinity for bovine albumin^[56] and human hemoglobin to the α1β2 interface.^[57]

Hesperidin can bind to bovine serum albumin and human hemoglobin, although the practical significance of this information is not certain since the body does not tend to absorb appreciable amounts of hesperidin (since hesperitin is found in the blood)

The glycoside form (Hesperidin) appears to be metabolized via intestinal microflora to form free hesperitin, where it is then taken up via the colonic wall into systemic circulation;^[50] similar to most flavonoid glycosides.^[58] Microbial fermentation of hesperidin may also produce small phenolic structures such as p-hydroxyphenylpropionic acid, p-coumaric acid, p-hydroxybenzoic acid, and phenylpropionic acid^[59][60] similar to naringenin.^[61]

Hesperidin may not be absorbed in the intestines, but metabolized by colonic fermentation to produce free hesperitin which is then absorbed from the colon to go into circulation; this delayed absorption (in the colon rather than small intestine) may explain the largely delayed T_max value following oral ingestion

After absorption, hesperitin can be metabolized by UGT enzymes to form hesperitin glucuronides,^[48] and it is near completely metabolized with up to 87% being found as hesperitin monoglucuronide and 13% as sulphoglucuronides.^[48] The glucuronides formed include 3'-O-glucuronide, 7-O-glucuronide, 5,7-O-diglucuronide, and 3',7-O-diglucuronide^[54] while the sulphogluduronide is thought to refer to Hesperitin-3'-O-sulphate.^[54] Consumption of hesperidin (via orange juice) alongside 150mL yogurt has been noted to reduce the C_max of the main metabolite (hesperitin-7-O-glucuronide) by 29% and overall exposure (AUC) by 27%, but overall hesperitin absorption was not changed;^[62] this was thought to be due to relative increases in other glucuronidation metabolites.^[62]

Hesperitin glucuronides may still be metabolically active, particularly hesperitin-7-O-glucuronide^[63] which seems to be the primary metabolite in humans^[62] as the other known one (hesperitin-3'-O-glucuronide) has only been detected in rats so far.^[62][64] The potency of hesperitin-7-O-glucuronide relative to hesperitin is mildly less potent.^[63][65]

After absorption, hesperitin is readily glucuronidated and seems to be glucuronidated mostly to hesperitin-7-O-glucuronide; this metabolite still appears to be active on some antiinflammatory and antioxidant actions of hesperitin

Studies measuring how much of oral hesperidin can be detected in the urine have noted levels of up to 24.4% (44mg hesperidin via orange juice^[66]) which progressively decreases with higher oral doses such as 32mg alongside 58mg of other flavonoids (14.2+/-9.1%^[49]), 126mg hesperidin via orange juice (4.9%^[47]), 110-220mg (4.1–6.4%^[48]), and 500mg in isolation (3%^[66]). Most of the urinary hesperidin is in the form of monoglucuronide, since most serum hesperidin after oral ingestion is the monoglucuronide.^[61]

While there is a delayed half-life near 5-8 hours with oral hesperidin possible due to the intestinal metabolism, most serum hesperitin is cleared within 24 hours.^[48]

Hesperitin is known to be cleared via the urine, and most hesperitin appears to be cleared from the body within 24 hours after ingestion of a single dose

Hesperitin has been noted to inhibit the aromatase enzyme with an IC₅₀ of 1µg/mL (comparable to Apigenin at 0.9µg/mL and Chrysin at 1.1µg/mL)^[67] with other studies noting inhibitory values (IC₅₀) of 4-5µM (underperforming apigenin at 1µM).^[68][69]

500-5,000ppm of hesperitin in the diet of mice bearing estrogen-responsive tumors (no dose-dependence although 1,000ppm was required for statistical significance) associated with a reduction in estrogen concentrations in serum.^[69] This level (ppm is comparable to µg/g and thus the dosage was 0.5-5mg/g in the diet) is approximately 120-500mg/kg (3g food intake per a 25g mouse assumption).

Hesperitin appears to be an aromatase inhibiting flavonone, with a potency either comparable to or slightly lesser than apigenin are a reference bioflavonoid

Androstenedione-induced induction of aromatase appears to be suppressed with hesperitin (0.1% of culture)^[69] although the mRNA appears to be increased in other studies at 5μM or higher.^[68] This study noted dose-dependent suppression with luteolin, another aromatase inhibiting flavonoid.^[68]

Mixed evidence as to how hesperidin modifies aromatase protein content

In regards to other enzymes, CYP2C8 is inhibited weakly to moderately by hesperitin with an IC₅₀ value in the range of 68-168µM^[25][70] while hesperidin is weaker at 209-274µM; both significantly weaker than other flavonoids such as quercetin or luteolin.^[70] The structurally related diosmetin (hesperitin if it were a flavone rather than a flavanone) is 16-fold more potent,^[25] suggesting the flavanone configuation per se hinders CYP2C8 inhibition. CYP2C9, on the other hand, is more potently inhibited by hesperitin with an IC₅₀ value of 21.50+/-3.62µM which is again less potent than diosmetin (1.71+/-0.58µM).^[24]

Orally administered hesperidin at 5-15mg/kg in rats, but not at 1mg/kg, appears to alter the pharmacokinetics of diltiazem and its metabolite (desacetyldiltiazem) by increasing the C_max (46.7-62.4%) and AUC (48.9-65.3%) suggesting CYP3A4 inhibition or inhibition of the efflux protein P-glycoprotein.^[71] While a concern (due to having an IC₅₀ of 2.7µM on enteric CYP3A4^[72]), hesperidin is not the main component of grapefruit juice that inhibits CYP3A4 (main component is bergamottin^[73]).

There are inhibitory properties of hesperidin ingestion or hesperitin incubation against CYP2C8 and CYP3A4, and both may be to a degree where drug-drug interactions may exist

Hesperidin has been noted to induce Nrf2 activity, resulting in an upregulation of heme-oxygenase 1 (HO-1; an antioxidative stress responsive protein^[74]) in liver cells at 40-80µM, this appears to be secondary to the MAPK pathway since hesperidin activate ERK1/2.^[75]

Despite the known antioxidant properties of hesperidin that are not mediated by its direct antioxidant sequestering effects (see the neuroprotection section), it seems that the concentration of hesperidin required to induce Nrf2 is quite high and this may not be a relevant pathway either

Hesperitin itself is glucuronidated by the UGT enzymes, specifically on the 3' and 7 position (hesperitin-3'-O-glucuronide and hesperitin-7-O-glucuronide, respectively) and this is mediated by numerous UGT enzymes including UGT1A9, UGT1A1, UGT1A7, UGT1A8, and UGT1A3.^[76]

Hesperitin (and eriodictoyl) have been noted to be inhibitors of sulfotransferase enzymes, with hepseritin inhibiting intestinal sulfotransferase enzymes with detectable IC₅₀ values against hSULT1A1 (23.4+/-5.75µM), hSULT1A3 (20.8+/-8.1µM), hSULT1E1 (90.4+/-11.5µM), and hSULT2A1 (152+/-14.9µM).^[77] The inhibitory effects against intestinal cytosolic sulfation were more potent, inhibiting estrogen sulfation with an IC₅₀ of 3.6µM.^[77]

Hesperitin is able to inhibit a variety of SULT enzymes (which sulfate molecules and signal for their elimination from the body), but the practical significance of this information is not known since it requires high concentrations of hesperitin to inhibit them

In regards to the transporter OATP2B1 (Organic Acid Transporting Polypeptide 2B1; one of the most relevant OATP transporters in the intestines^[78][79]), both hesperidin and hesperitin are able to inhibit estrone-3-sulfate induced uptake (suggesting inhibition) with IC₅₀ values of 1.92μM and 67.6μM respectively;^[80] similar selectivity was seen with the glycoside naringin (4.63μM) relative to the aglycone naringenin (49.2μM) suggesting a role for the rutinoside group.^[80] Hesperidin was said to be a major determinent of the inhibitory effects of orange juice on OATP2B1 due to its high concentration, and after correcting for its concentrations in the juice they seemed more relevant but less so than 6',7'-dihydroxybergamottin (also found in orange juice)^[80]

A 0.079% hesperidin suspension given to rats for eight weeks is able to increase the overall exposure (147%) and peak concentration (138%) to the drug pravosin,^[81] which is thought to be due to inhibition of the transport protein known as Multidrug Resistance Protein 2 (MRP2) that mediate pravosin efflux into the intestines after absorption^[82] and was also seen with orange juice.^[81] At least when looking at studies on orange juice, overall expression of the receptor is not change in humans with one time usage of 200mL extra strength OJ thrice daily,^[83] but mRNA and protein expression is decreased after eight weeks of supplementation of hesperidin in rats.^[81]

There are inhibitory effects on two intestinal transporters, the OATP2B1 transporter and MRP2. OATP2B1 appears to be acutely inhibited with supplementation of hesperidin, whereas low doses of hesperidin over a few weeks appear to downregulate the MRP2 transporter

In a screening process in yeast for longevity promoting flavonoids, it was found that hesperidin was able to increase activity of the sir2 gene (human homologue is SIRT1) and superoxide dismutase (SOD) resulting in less reactive oxygen species production;^[84] these benefits were not seen with the aglycone hesperitin.^[84]

Elsewhere, hesperidin (and rutin; the rhamnoside of quercetin) have been noted to increase neural crest cell viability (neural progenitor cells) with peak efficacy at 20µM; the potency being comparable between both rhamnosides and not present with quercetin, implicating the rhamnoside group itself.^[85]

Hesperidin has been found to stimulate the SIRT1 gene, but this information is not thought to be relevat to oral supplementation sinc hesperidin is not well absorbed and hesperitin has been confirmed to be inactive

Dopamine concentrations in the brain are not significantly influenced with four weeks oral supplementation of 50mg/kg hesperidin to rats,^[86] and blocking the D1 or D2 dopamine receptor does not prevent the anti-depressant effects of hesperidin.^[87]

No known interactions with dopamine metabolism in the brain following hesperidin/hesperitin interventions

50mg/kg hesperidin daily for 28 days to rats failed to significantly influence brain levels of noradrenaline and adrenaline relative to control rats,^[86] and propanolol (β-adrenergic receptor blocker), Yohimbine and Prazosin (α-adrenergic blockers), and an inhibitor of tyrosine hydroxylase (AMPT) have all failed to prevent the antidepressant effects of hesperidin, suggesting that noradrenergic signalling is not involved in the antidepressive properties.^[87]

Hesperidin does not appear to influence the adrenergic signalling system, and due to no influence on dopamine either it is currently thought to not influence catecholamines whatsoever

Although four weeks ingestion of 50mg/kg hesperidin in rats does not significantly influence serotonin concentrations in the brain,^[86] the antidepressant effect of hesperidin has been noted to be inhibited by blocking the 5-HT_1A receptor while blocking the 5-HT_2A/2C or 5-HT₃ receptors did not affect anything.^[87] 

Hesperidin itself has a K_i towards the 5-HT_2B receptor (5.3µM), the 5-HT_2C receptor (20.9µM), and the 5-HT₆ receptor (21.9µM), and while the affinity on 5-HT_2B is significantly less than related flavonoids nobelitin (310nM), tangeretin (590nM), and 3,3',4',5,6,7,8-heptamethoxyflavone (210nM) it was the only tested flavonoid with inhibitory actions on 5-HT₆ while only isoliquirtigenin (licorice) also inhibited 5-HT_2C.^[88]

Hesperidin does not alter serotonin concentrations, but it seems that the antidepressant effects of hesperidin do involve serotonin signalling while it is not sure exactly how right now

The antidepressant effects of hesperidin injections are not blocked with caffeine, and adenosine receptor antagonist.^[89]

Currently no known interactions with adenosinergic neurotransmission noted with hesperidin

50-100mg/kg hesperidin orally for two weeks prior to an immobilization stress test was able to exert neuroprotective effects (33-76% reduction in lipid peroxidation and preservation of mitochondrial function) in a manner inhibited by nitric oxide donors (L-arginine) and potentiated by NOS inhibitors (L-NAME),^[90] suggesting negative regulation of nitric oxide signalling in the protective effects of hesperidin.^[90]

The neuroprotective effects appear to involve nitric oxide signalling, where excessive signalling from nitric oxide (exacerbates pathology) is suppressed with hesperitin and overcoming this suppression will prevent hesperitin from protecting the brain

When tested in vitro, hesperidin failed to displace a ligand of the μ-opioid receptor at concentrations up to 300μM while hesperitin was effective with a K_i value of 39.04+/-1.32μM while was significantly less than the reference drug naltrexone (0.21+/-0.01nM).^[91] Hesperitin at high concentrations (200μM) still has managed to induce opioidergic signalling, but in a manner not blocked by naltrexone.^[91]

Injections of hesperidin has been found to have analgesic properties via the μ-opioid receptor, since κ-opioid and δ-opioid antagonists due not block the observed effects suggesting that hesperidin acts similarly to morphine.^[91]

Injections of hesperidin (not practical to oral supplementation, since oral supplementation digests most hesperidin into hesperitin) appear to stimulate μ-opioid siganlling and due to this possess weak sedative and analgesic properties

0.1-1mg/kg hesperidin (intraperitoneal injections) appears to have antidepressant mechanisms that work vicariously through the κ-opioid receptor^[89] without signalling through δ-opioid, μ-opioid, or a peripherally acting κ-opioid antagonist nor caffeine (since adenosine, which caffeine inhibits the signalling or, may also signal via opioid receptors^[92]) and appeared to be synergistic with morphine at a subeffective dose of hesperidin (10µg/kg intraperitoneal injection).^[89]

Oral supplementation of hesperidin for anti-depressive effects seem to involve opioidergic signalling as well as serotonin signalling, but a completely different receptor (κ-opioid) is implicated with hesperitin

In isolated PC12 cells, hesperitin at low concentrations (100-1,000nM) has been found to activate neuronal growth factors (Akt/ERK and CREB) and antioxidant factors (seladin-1^[93] and PGC-1α^[94]) in a manner that is dependent on the TrkA receptor and estrogen signalling.^[95] Due to estrogen inhernetly being neuroprotective^[96] associated with both Akt^[97] and selandin-1^[93] it is thought that hesperitin is neuroprotective by being an estrogen mimetic, and while all of these effects were dependent on both fators (TrkA and estrogen signalling) the increase in selandin-1 was fully dependent on estrogenic signalling.^[95]

50μM hesperitin was also neuroprotective against H₂O₂, but this was due to direct antioxidant properties and is not thought to be relevant to oral supplementation of hesperidin as it is too high a concentration.^[95]

Hesperitin appears to act via both estrogenic signalling and TrkA (the receptor for BDNF) to orchestrate an increase in antioxidant defenses and pro-survival proteins, which is thought to be the mechanism underlying an inhibition of cellular death from oxidative toxins or stressors

In irradiated rats (causes reduced mitochondrial capacity of the brain and reduced neurotransmitter levels due to oxidative damage), hesperidin at 50mg/kg oral ingestion daily for 10 days prior to irradiation and two weeks afterwards was able to attenuate the oxidation (40% attenuation of reduced thiols) and changes in neurotransmitters (49-60% attenuation) while hesperidin without irradition failed to have any influence.^[86] Preservation of mitrochondrial capacity has been seen with a two week preload (50-100mg/kg in mice) prior to an immobilization stress test^[90] which is known to increase NOS activity,^[98] and aside from these neuroprotective effects being mediated secondary to nitric oxide inhibition it was noted that the reduction in lipid peroxidation (33-76%) was blocked when nitric oxide inhibition was circumvented with L-Arginine and potentiated with L-NAME (NOS inhibitor).^[90]

When looking directly at mitochondrial function the impairments to complexes I, II, and IV seen with stress is partially preserve with 50-100mg/kg hesperidin and fully preserved with coingestion of L-NAME.^[90][99]

There appear to be antioxidant effects in the brain where hesperidin reduces the increase in lipid peroxidation during cognitive damange, but this appears to be indirect through nitric oxide signalling (inhibition) rather than a direct antioxidant effect

Various other protective effects have been noted in rodents with ingestion of 50mg/kg hesperidin alongside cisplatin,^[100] ischemia-reperfusion injury,^[101][99] and MCAO-induced stroke,^[102]; some of these effects, similar to the aforementioned mitochondrial preservation, are dependent on nitric oxide signalling.^[103][99]

Hesperidin appears to have a variety of neuroprotective effects at relatively standard oral doses, and these also seem to be dependent on suppressing errant nitric oxide signalling (causing an antioxidant and antiinflammatory defense)

Secondary to signalling via both TrkA and the estrogen receptors, BDNF is also increased with hesperitin to 1.25-fold over control despite being in the presence of H₂O₂ (normally suppresses BDNF secretion).^[95]

One study has noted intraperitoneal injections of hesperidin (10mg/kg) have inhibited phosphorylation of ERK1/2^[104] which are increased following activation of TrKA and estrogen signalling,^[95] but this is not thought to be relevant to oral supplementation due to conversion of hesperidin into hesperitin in the colon.

Hesperitin is able to increase levels of BDNF and also relieve the inhibitory effects of prooxidants on BDNF secretion

Chin-pi (aurantii nobilis) is able to attenuate the age-related reductions in myelination when consumed as 1% of the drinking water, and this depends on the FcRγ/Fyn-MBP cascade (known to promote myelination^[105]) since double-deficient mice were impervious to the effects.^[106] It was noted in vitro that hesperidin activated the FcRγ/Fyn signalling pathway, but hesperitin was not tested.^[106]

Preliminary evidence suggests an increase in myelination with the fruit peel which contains hesperidin

When injected into rats (intraperitoneally), hesperidin (but not hesperitin) shows analgesic effects in an acetic acid writhing test with 0.6-1mg/kg having 53.9-90.2% efficacy. These effects were thought to be due to the opioidergic effects of hesperidin injections.^[91]

Injections of hesperidin appear to have potent analgesic properties due to acting like a µ-opioid activator (like morphine), but this more likely than not doesn't apply to oral supplementation of hesperidin

In a model of memory dysfunction assocaited with ischemic stroke, supplementation of hesperidin (50-100mg/kg oral for a week prior to ischemia) is able to minorly attenuate the memory loss seen in an elevated maze plus test in a manner that is associated with suppressing excessive nitric oxide signalling.^[99] The magnitude of memory loss (assumign that control was 100% reduction) was reduced to around a 20-60% reduction in a dose-dependent response, with neither dose normalizing to undamaged control.^[99]

Appears to be moderately anti-amnesiac when orally supplemented prior to brain damage, with no known nootropic properties at this moment in time

Injections of 0.1-1mg/kg hesperidin (intraperitoneal) to mice subject to a force swim test is able to exert antidepressant effects while 10µg/kg was ineffective on its own^[89] and this has been replicated elsewhere in forced swim and tail suspension tests with a potency comparable to imipramine (15mg/kg injection) and fluoxetine (32mg/kg injection) at the dose of 0.3-1mg/kg.^[87]

There appear to be antidepressive effects assocaited with hesperidin

In a study which found antidepressant effects with intraperitoneal injections of hesperidin (0.1-1mg/kg), there was no apparent anxiolytic effect^[89] and this lack of effect has been noted elsewhere with oral ingestion of 20-100mg/kg hesperidin.^[87][91] Anxiolytic effects can be forced with high doses of hesperidin injections (2-30mg/kg) in mice,^[91] thought to be related to the opioidergic signalling.

There do not appear to be appreciable yet inherent anxiolytic properties with hesperidin unless high doses are injected

One study using hesperidin (50-100mg/kg) for two weeks prior to an immobilization stress test which then measured anxiety afterwards (elevated maze plus test) was able to partially attenuate the increase in anxiety seen in control in a manner that is inhibited when the neuroprotective effects are blocked (via circumventing nitric oxide inhibition).^[90]

It seems that anxiety reducing properties may exist under the specific condition that stress causes neurological damage resulting in anxiety, since the damage is attenuated with hesperidin (and thus, less anxiety due to less damage)

Ghrelin administration is known to enhance food intake^[107] possible secondary to growth hormone secretion^[108] and a Kampo formulation known as Rikkunshito is known to stimulate Ghrelin secretion^[88][109] via antagonism of the serotonergic 5-HT_2B/2C receptors; in Rikkunshito, hesperidin is thought to be active.^[88]

Hesperidin by itself at 5mg/kg orally to rats (where anorexia was induced by cisplatin) appears to attenuate the reduction in food intake seen with cisplatin by 59% while as a potency comparable to 1,000mg/kg Rikkunshito but lesser than the synthetic 5-HT_2C receptor antagonist SB242084HCl (full negation),^[34] and the attenuation of anorexia seen with all of the three aforementioned was prevented with a GHS-R1a (Growth hormone secretagogue receptor) antagonist,^[34] which is the receptor that Ghrelin acts upon.^[110]

Hesperidin has been confirmed to be active following oral administration to rats in suppressing anorexia (causing an increase in appetite where there normally is none) in a manner that is thought to be mediated by serotonin signalling and is dependent on the actions of Ghrelin

Hesperidin has been described as a sedative flavanone^[104] possibly due to injections of hesperidin having suppressive effects in rodent locomotor tests^{[111][104][91][112]} with an ED₅₀ of 11.34+/-2.48 mg/kg^[113] possible related to its opioidergic signalling (via the μ-opioid receptor).^[91] This does not occur with oral ingestion of hesperidin in the range of 20-100mg/kg,^[111] possibly because orally ingested hesperidin is metabolized to hesperitin and the aglycone (hesperitin) does not possess this opioidergic activity.^[91] Injections may be synergistic with benzodiazepines (GABA_A receptor agonists) as well, but this may not extend to oral intake.^[112]

That being said, oral ingestion of hesperidin has been noted to signal in a manner dependent on κ-opioid receptors^[89] and pharmaceutical κ-opioid agonists have been noted to have weak sedative effects.^[114] It is not known if oral supplementation of hesperidin confers sedative effects at higher doses.

While injections are thought to have sedative properties secondary to opioidergic signalling, there is no significant or known influence of orally ingested hesperidin on locomotion or sedation

Hesperidin at 100mg/kg orally to young and old rats for 90 days is able to partially reverse the worsening of antioxidant enzymes seen in heart tissue with aging, while the changes to these enzymes in young hearts were not significant;^[115] a decrease in lipid peroxidation and protein carbonylation, and this was thought to be due to an increase in Nrf2 expression seen in the aged hearts that was decreased with aging (there was no increase in youth).^[115]

Oral administration of Hesperidin at reasonable supplemental dosages has once been noted to benefit the cardic tissue of older rats, but not youthful ones

In a model of ischemia/reperfusion, 100mg/kg hesperidin orally for 15 days prior to cardiac injury was able to nearly normalize mean arterial pressure and heart rate while attenuating (28% attenuation for +dp/dt and 67% for −dp/dt) the changes in ventricular contractility.^[116]

In response to various stressors, there are significant reductions in lipid peroxidation (77% attenuation with 100mg/kg before ischemia^[116]), nitrite (normalization with 100mg/kg for 15 days prior to ischemia,^[116] 60% attenuation in serum against doxorubicinwith 200mg/kg hesperidin^[117]), lactate dehydrogenase (normalization against doxorubicin^[117]), and creatine kinase (77% attenuation with 200mg/kg against doxorubicin for a week^[117]).

At least one study has used hesperidin after the stressor (isoproterenol), and a week of 200mg/kg hesperidin is able to attenuate some structural changes to the heart (cholesterol, phospholipid, and triglyceride content) but did not measure typical biomarkers^[118] whereas another study measuring the more common biomarkers with similar methodology found that 200mg/kg hesperidin (more effective than 100mg/kg yet 400mg/kg was no more effective) for one week after cardiac stress attenuated the increases in lactate dehydrogenase (87%) and creatine kinase (full protection) with reductions in lipid peroxides (70%) and TBARS (86%).^[119]

Hesperidin appears to protect the heart following oral ingestion against a variety of stimuli, and can work in either a prophylactic or rehabiliative manner in as little as one week. Despite no human studies on it at this moment in time, it seems surprisingly potent at reducing lipid peroxidation and markers of cardiotoxicity

1-10μM hesperitin has been noted to greatly attenuate the increase in VCAM-1 in response to TNF-α and slightly suppressed VCAM-1 expression per se when not tested in the presence of TNF-α, suggesting less adhesion of molecules to the cell wall in response to inflammation.^[120] This property of hesperitin is preserved when it is metabolized into its major metabolite (hesperitin-7-O-glucuronide) but not into a minor metabolite where the B ring is the target (hesperitin-3'-O-glucuronide).^[63] An inhibition of ICAM-1 upregulation has also been noted in the presence of high glucose concentrations, where ICAM-1 would normally be upregulated and of concern to diabetics^[121] but is inhibited by hesperidin, but it occurred at higher than normal concentrations (30μM).^[122]

When 500mg of hesperidin is given to participants with metabolic syndrome for three weeks, there is no significant change in VCAM-1 levels in serum but a significant decrease in E-selectin (13%) and some other inflammatory biomarkers associated with cardiovascular disease such as high sensitivity C-Reactive Protein (33%) and Serum amyloid A proteins (23%).^[120] In otherwise healthy men given 292mg hesperidin for four weeks, a nonsignificant trend to reduce sCAM-1 has been noted while ICAM-1 and VCAM-1 were not affected.^[123]

May reduce the ability of inflammation to promote adhesion of molecules to the endothelial wall, and this occurs at a concentration which is probably relevant following oral ingestion (and metabolism of hesperitin may only minorly affect this property); limited human evidence support a minor antiinflammatory and antiadhesion effect

Hesperitin has been noted to upregulate the ABCA1 transporter (5-15μM; more than three-fold in vitro) and promote cholesterol efflux from macrophages,^[124] a mechanism thought to promote HDL-C production due to efflux of cholesterol towards Apolipoprotein A1^[125] which was noted with hesperitin in a manner correlated with ABCA1 expression LXR promoter activity and partially accreddited to PPARγ activation^[124] since PPARγ complexes with and coactivates LXR^[126] that is known to mediate this response.^[127][128]

Hesperitin is thought to promote HDL-C formation via influencing LXR activity, which increases ABCA1 activity to shuttle cholesterol towards HDL-C

In vitro in an LDL oxidation test, hesperitin is able to prolong the time for LDL to be oxidized (2-9.3μM) with a potency comparable to quercetin associated with less lipid peroxidation; 20μM resulted in prooxidation.^[129]

500mg of G-Hesperidin has been noted to reduce the particule size of LDL cholesterol only in persons with high blood triglycerides (150mg/dL) after 24 weeks of supplementation, indicating less risk for atherogenesis;^[130] this has been thought to occur elsewhere due to a decrease in Apolipoprotein B^[131] since a reduction in ApoB relative to LDL cholesterol significes an increase in LDL particle size and reduced atherogenicity^[132] but later confirmed with polyacrylamide gel electrophoresis.^[130]

Some biomarkers of atherosclerosis (LDL particle size, adhesion molecules) show minor changes which suggest supplemenal Hesperidin can reduce the risk for atherosclerosis

In isolated endothelial cells, 1-10μM hesperitin has been noted to phosphorylated Ser1179 which resulted in its increased activity,^[120] which is thought to be due to phosphorylation from AMPK^[133] or Akt^[134] on eNOS since both of those proteins were activated from hesperitin.^[120] Blocking either protein resulted in attenuation of eNOS activation from hesperitin and preventing ROS formation (with incubations of N-acetylcysteine) blocked the effects, and similar to EGCG from green tea catechins^[135] it was attributed to th Src protein known as Fyn (which acts on PI3K to then influence the two proteins, and is stimulated by the radical H₂O₂^[136]) where the hydroxyl groups have been noted to be critical to production of H₂O₂ from EGCG^[137] and are thought to be the same for hesperitin.^[120]

Hesperitin has also been tested at a slightly higher concentration of 12.5µM in HUVEC cells, and the increase in nitric oxide production was significantly attenuated with estrogen blockers.^[138] Hesperitin also increased eNOS transcription at 50µM, but these effects were not observed with naringenin (which was also estrogenic) while being observed with 10nM 17β-estradiol.^[138] Estrogen signalling via the alpha subset (ERα)^[139] is also involved in producing nitric oxide (via increasing eNOS phosphorylation at Ser1179^[140] secondary to Src siganlling, where Fyn is implicated by c-Src is more important^[141]), which suggests that estrogenic signalling may underlie the observed benefits.

Mechanistically, hesperidin and hesperitin increase nitric oxide via siganlling through Src proteins (including Fyn) to make AMPK and Akt activate the enzyme that makes nitric oxide in blood vessels (eNOS). This is either due to producing hydrogen peroxide (via the hydroxyl groups being donated) or through estrogen signalling

In regards to microcirculation, in otherwise healthy but overweight men given 292mg hesperidin daily for four weeks there was no significant influence on circulation under fasted conditions; when measured six hours after oral ingestion of hesperidin, however, there was an increase seen with both isolated hesperidin and an equivalent amount via orange juice consumption.^[123] This increase in microcirculation was noted with a trend to increase nitrate concentrations in plasma that failed to reach statistical significance.^[123]

May be able to increase microcirculation when it is in the blood, but this appears to be a transient increase and may be related to an increase in nitrate and blood flow

Oral intake of G-Hesperidin in spontaneously hypertensive rats (SHRs) was able to acutely reduce blood pressure in rats with hypertension in the dosage range of 10-50mg/kg reaching peak efficacy at 30mg/kg and lasting over 24 hours with peak efficacy after 9-12 hours (reaching 8-9mmHg systolic; 12.3%), while rats with normal blood pressure failed to see significant benefit.^[131] The higher dose (50mg) fed for eight weeks in SHRs has reduced blood pressure within a week where it stayed static for eight weeks, and improved vascular reactivity.^[142]

Hesperidin is known to be heavily glucuronidated following oral ingestion, and while glucuronidating it on the 3' carbon nullifies its blood pressure reducing effects they are unaffected when glucuronidated on the 7-carbon (hesperitin-7-O-glucuronide).^[63]

500mg hesperidin taken daily for three weeks in persons with metabolic syndrome was able to improve blood flow as assessed by FMD (24.5% increase; placebo experiencing a 6% decline) despite no influence on blood pressure nor any change in nitroglycerin mediated vasodilation.^[120] Otherwise healthy persons who experience transient improvements in microcirculation have faile to find any influence on systolic blood pressure, although a mild reduction in diastolic blood pressure has occurred.^[123]

Oral intake of hesperidin appears to benefit general blood flow, and has mixed effects on blood pressure (either a mild decrease or no significant effect). These beenfits appear to be fairly fast acting after oral administration (within a day) but do not appear to persist over the long term

G-hesperidin has been noted to suppress the secretion of Apolipoprotein B from HepG2 (liver) cells mildly at concentrations of 100µM and above when coincubated; this may be due to donating hesperitin since it was active to the same degree at 25-50µM, and it appeared that the overall production of apolipoprotein B was reduced to a comparable level as the reduction in secretion.^[27] This reduction of Apolipopotein B has been noted in vivo with 500mg of G-Hesperidin.^[130]

Mechanistically, hesperidin appears to cause a relative suppression of Apolipoprotein B (relative to apolipoprotein A1) which would suggest an increase in HDL cholesterol formation

Supplementation of G-Hesperidin (100mg/kg) to rats daily for four weeks alongside daily swimming sessions noted that both supplementation and exercise increased HDL-C in an additive manner, with the group recieving both having a 55-58% increase over control while G-hesperidin alone increased it 35%.^[143]

In rats, the improvements in cholesterol appear to be additive with exercise

Supplementation of G-Hesperidin (100mg/kg) to rats for four weeks results in a decrease in total cholesterol (16%) and LDL cholesterol (52% reduction) which is additive with exercise since the pairing reaches 24% and 81% reductions relative to sedentary control, respectively.^[143]

500mg of hesperidin daily for three weeks in persons with metabolic syndrome is able to cause a very mild decrease in both total cholesterol (2.8%) and HDL-C (5.5%) with no significant influence on triglycerides nor LDL-C^[120] and in hyperlipidemics there is a mild decrease in total cholesterol and LDL-C (no influence on HDL-C) which is normalized four weeks after the supplementation of 500mg G-Hesperidin ends.^[130] In persons given a higher dose (800mg) of hesperidin daily for four weeks, these subjects with mildly high cholesterol (6.18mM) failed to find benefit on any parameter with supplementation relative to placebo^[144] and otherwise healthy persons do not experience any significant changes.^[123]

Despite the above, orange juice has been noted to increase HDL-C at 750mL daily in men with high cholesterol by 21%^[145] which is despite a sugar intake, which is known to transiently suppress HDL-C in this population when ingested via juice or food products.^[146][147]

While orange juice appears to have some evidence to suppport an increase in HDL-C, this does not appear to be related to the hesperidin content since supplemental hesperidin only causes a mild improvement in cholesterol in those with the worst cholesterol profiles and is otherwise ineffective

In rats, 100mg/kg G-Hesperidin daily for four weeks is able to reduce triglycerides by around 13%; this reduction was mimicked by exercise, but the two were not additive.^[143]

In hyperlipidemics (baseline TG above 150mg/dL) given 500mg of G-Hesperidin daily for 24 weeks, there was a significant reduction in serum triglycerides after four weeks (up to 34%) which was maintained in magnitude over the 24 weeks of supplementation yet normalized to baseline values after four weeks cessation.^[130] Hyperlipidemics with less than 150mg/dL (110-150) had no obvious changes at any time point^[130] which has been replicated in subjects with mild hypercholesterolemia but no alterations in triglycerides (where there was no benefit with 800mg daily over four weeks).^[144]

Despite these lacklustre effects with isolated hesperidin, orange juice itself (750mL but not 250-500mL) has been noted to increase plasma triglycerides by 30% in persons who did not have hyperlipidemia (but had high cholesterol) in the first place from 1.56+/-0.72mM to 2.03+/-0.91mM, which correlated with increases in vLDL and did not put subjects into a hyperlipidemic state.^[145] It was thought that this is reflective of the sugar intake, since sugars themselves increase plasma lipids,^[146][147] and does not occur in men with normal cholesterol.^[148]

There may be a mild decrease in triglycerides seen in those with very high triglyceride at baseline, but otherwise hesperidin does not have a significant influence on triglycerides. Orange juice may increase triglycerides secondary to the sugar content, and hesperitin is not thought to influence this when coingested

Hesperidin and hesperitin both have direct inhibitory effects on protein glycosylation when tested at 1mM in the BSA-glucose and RNase A-MGO assays, reaching 33.6-45.8% (hesperidin), 37-56.7% (hesperitin), and 27.7-43.5% inhibition (G-hesperidin) with the isomerization of the hesperitin molecule not affecting results.^[26]

Appears to be able to directly suppress formation of advanced glycemic end products (AGEs), but at a higher than average concentration suggesting a direct mechanism may not be relevant following oral ingestion

In diabetic rats (streptozotocin), 100-200mg/kg hesperidin fed daily for twelve weeks is able to mildly suppress the elevations of blood glucose^[149] and this has been noted elsewhere to be around 27% with 200mg/kg of hesperidin over twelve weeks.^[150]

Supplementation of 500mg hesperitin daily for three weeks in persons with metabolic syndrome trends towards improving insulin sensitivity to a very mild degree (less than 1% improvement) while there are no significant improvements in blood glucose nor fasting insulin concentrations; HbA1c also appears to not be significantly affected.^[120]

Hesperitin has been noted to stimulate PPARγ and PPARα activity in a concentration dependent manner between 20-160μM;^[151] secondary to this, hesperitin could induce secretion of adiponectin from 3T3-L1 adipocytes with 80μM hesperidin having similar potency to 10μM rosiglitazone.^[151]

Intra-gastric administration of 200mg/kg G-hesperidin (more effective than 66-133mg/kg and 266-333mg/kg) in anesthetized rats was able to increase intrascapular brown adipose tissue-sympathetic nerve activity (BAT-SNA),^[152] suggesting an increase in metabolic rate.

Some interactions with brown fat in regards to neural activation thereof, but the practical relevance of this information in humans is not known but seems to occur at the supplemental dosage

Hesperitin (100μM) is able to suppress lipolysis induced by TNF-α in 3T3-L1 adipocytes,^[153] which is though to be due to preventing TNF-α from activating NF-kB via ERK resulting in less IL-6 secretion;^[153] since IL-6 itself induced lipolysis in adipocytes^[154] and is associated with metabolic syndrome,^[155] it was then investigated and ablating IL-6 prevented the effects of hesperitin.^[153]

Hesperitin is thought to have antiinflammatory properties in fat cells, and while this technically does occur it happens at a rather larger concentrations and has not yet been confirmed in a living model

In isolated myoblast C2C12 cells, hesperidin (100µM) is able to promote myocyte differentiation in low mitogen medium^[156] associated with more activity of Myogenin, a muscle cell growth factor downstream of MyoD,^[157] and MCK without any influence on either MyoD nor MEF2C transcription.^[156] It appeared that hesperidin merely enhanced MyoD actions on the genome (not influencing the interaction of MyoD and MEF2C), resulting in enhanced transcription of myogenin and MCK.^[156]

In mice subjected to freeze injury (tibialis) followed by hesperidin injections at 50mg/kg for six days, muscle regenerative capabilities appeared to be significantly enhanced relative to control.^[156]

Very high concentrations of hesperidin have been noted to promote muscle regeneration, but this probably does not apply to oral ingestion of hesperidin due to not only the concentration being too high but the aglycone (hesperitin) found in blood not being tested

Hesperitin can be taken up into osteoblasts in the 1-10μM range^[158] which is thought to be biologically relevant as, aside from the low concentration, hesperitin-7-O-glucuronide as exerts similar effects on osteoblasts as hespertin^[159] suggesting deglucuronidation outside the cell.

1-10μM hesperitin has been noted to promote osteoblastic proliferation and differentiation over 19 days of incubation, resulting in calcium nodule formation.^[158] This was thought to be due to the BMP signalling pathway (an increase in BMP2 and BMP4 mRNA being noted) although influences on MAPK and AP-1 signalling was noted.^[158]

In an in vitro model of diabetes induced bone disease (2-deoxy-D-ribose induced oxidative stress), hesperitin is able to minorly increase cell viability at 0.1-10µM in osteoblasts (MC3T3-E1) associated with concentration-dependent increases in collagen content and ALP secretion.^[160]

In periodontal ligament stem cells (PLSCs; stem cells in the oral cavity such as teeth,^[161] although PLSCs are those from ligament^[162]) that are either under normal glucose concentrations (5.5mM) or diabetic ones (30mM), hesperitin (1-10µM) can increase osteogenic differentiation under normal conditions (1.8 to 2-fold) and inhibit the suppressive effects of high glucose thought to be secondary to stimulating Wnt/β-catenin signalling.^[163]

One study in otherwise healthy rats given 0.5% hesperidin in the diet (55mg/kg) for three months noted that in youthful rats, but not older ones, there was an increase in bone growth associated with hesperidin intake.^[164]

In young rats, relatively reasonable doses of hesperidin (found in supplements or orange peels) can increase bone growth rates; this enhancement of bone growth rates was not seen in older rates with fully developed bones

In male mice with androgen-deficiency related bone loss given hesperidin (0.5%) or G-hesperidin (0.7% of the diet) for four weeks noted an attenuation of bone loss relative to control.^[165]

Oral supplementation of 0.5% hesperidin (around 55mg/kg) in ovarectomized rats (model of menopause) was able to partially attenuate bone losses seen from ovaracetomy, with no apparent influence on uterine weight suggesting no relevant estrogenic effects;^[164] these effects were associated with a plasma concentration of 3.57+/-0.68μM hesperitin^[164] and have been noted elsewhere with 0.5% dietary hesperidin or its 7-O-glucoside.^[166]

Hesperidin ingestion at the standard supplemental dose appears to attenuate bone loss seen in both menopause models (estrogen deficiency) as well as in androgen deficiency rat models

Hesperidin itself appears to share approximately 46% of the genetic influences of orange juice on leukocytes which suggests that it is a major factor in orange juice mediated immune effects (mostly related to reduced leukocyte adhesion and transport)^[167] although overall leukocyte count is unaffected with oral ingestion of 296mg of hesperidin daily for four weeks in otherwise healthy subjects.^[168]

At this moment in time, it seems that hesperidin likely mediates most of the effects of orange juice on this particular subset of white blood cells (leukocytes) but it is not certain what these effects are

When hesperidin is tested against irradiation, preincubation of hesperidin at concentrations exceeding 3.27µM show concentration-dependent protective effects with maximal potency at 16.38µM which reduced presence micronuclei (59.85+/-4.56%) and dicentric aberrations (25.02+/-1.90%) indicative of less DNA damage.^[169]

Elsewhere, 50-200mg/kg oral hesperidin for six weeks where irradiation was also administered (week two and onward) is able to mildly attenuate the suppressed immune system in these rats.^[170]

May be mildly protective of immune cells

Consumption of 296mg of hesperidin daily for four weeks in otherwise healthy subjects has failed to modify overall count of NK cells or their activity.^[168]

When hesperidin is consumed at 296mg daily for four weeks in otherwise healthy persons, there is no significant interaction with the oxidation produced by polymorphonuclear neutrophils in response to stimulation.^[168]

Hesperidin has been found to dock onto c-Kit and prevented structurally changes and p38 activation from stem cell factor (SCF) when hesperidin was incubated at 0.01mg/mL, although with a slightly lesser potency than 100nM dexamethasone; hesperitin was not tested in this study.^[35] c-Kit is a receptor on mast cells for SCF^[171] and activation of mast cells by SCF tends to result in a structural changes conducive to migration and a release of inflammatory cytokines causing an allergic reaction.^[172][173]

Hypoxia inducible factor-1 (HIF-1) is a protein with two subunits, and the alpha subunit (HIF-1α) is normally induced in instances of low oxygen^[174] but can be induced in normal conditions via ERK1/2;^[175] in mast cells HIF-1α activation is known as a pro-allergetic response and inhibiting it can suppress allergic reactions,^[176] and hesperidin (0.1mg/mL) has been noted to suppress HIF-1α by blocking ERK signalling.^[177]

While hesperidin is known to block the c-Kit receptor which would have anti-inflammatory effects on immune cells, it is not certain if this occurs in the body following supplementation since hesperidin is fully metabolized to hesperitin

It is known that the Korean Pyeongwee-San extract (KMP6) has anti-allergic properties^[178][179] and hesperidin is thought to play a role since, in isolation, 5mg/kg oral ingestion of hesperidin (but not 1mg/kg) thrice weekly for five weeks in ovalbumin sensitized mice is able to reduce lung infiltration of white blood cells (eosinophil, B-cell, and T-cell) and reduce the levels of ovalbumin specific IgE.^[180]

Fairly low doses of hesperitin have some evidence for their usage against allergic disorders where an antigen is present

The increase in synoviocyte proliferation seen with Freund's complete adjuvant (induces rheumatism in rats) which contributes to the pathology of rheumatism by secreting inflammatory cytokines such as IL-1β^[181] and TNF-α^[182] is suppressed with hesperidin at 80-160mg/kg oral intake over three weeks.^[183] The suppression in synoviocyte proliferation and the mRNA levels of IL-1β and TNF-α were normalized (with an increase in IL-10, an antiinflammatory cytokine), but the attenuations in cytokines were not absolute for IL-10 (12.5-39.1% preservation), IL-1β (38.5-47% normalized to control) and TNF-α (28.9-45% normalized to control).^[183]

Hesperidin appears to potently suppress synoviocyte proliferation and mildly suppress their alterations in cytokine secretion (which would influence T-cell function) when pathologically altered with a rheumatic research toxin

Hesperidin (75mg/kg) and hesperitin (150mg/kg) both can acutely reduce paw edema in a mouse model of rheumatism (carrageenan injections) when injected, with a potency peaking at three hours and overall less than both Phenylbutazone (80mg/kg) and quercetin (75mg/kg).^[184] Only the flavanones (hesperitin and hesperidin) were effective against xylene-induced ear swelling though,^[184] and since this is a model of neurogenic inflammation^[185] it is thought that all tested flavonoids can suppress immune cell mediated inflammation but only the flavanones suppressed that from the neurons.

The immune system is thought to play a role, as the alterations in T-cell activity and reduction in IL-2 seen with adjuvant induced arthritis are attenuated with hesperidin intake^[186]

Hesperidin (and hesperitin) are thought to be able to reduce the inflammation from neurons as well as cause a normalization of altered T-cell function that is seen in rat models of rheumatism, and these changes are thought to be therapeutic to rheumatoid arthritis

In a rat model of collagen-induced arthritis (to induce rheumatoid arthritis^[187][188]) where hesperidin was given at 160mg/kg for three weeks after induction of arthritis was able to mildly decrease the arthritic index (24%) and elastase activity in joint tissue, although the reduction in lipid peroxidation was of higher magnitude.^[189] This has been noted elsewhere in a similar research model in mice (150mg/kg hesperidin or 75mg/kg hesperitin)^[190] and again in rats given arthritis with Freund's complete adjuvant (another model of rheumatism) associated with beneficial changes in T-cell activities and IL-2 at 80-160mg/kg oral intake for three weeks.^[186][183]

Similar to what is seen in the kidneys, the therapeutic effect in research animals seems to be less than the large reduction in lipid peroxidation would suggest

One human trial in nineteen persons with rheumatoid arthritis given G-Hesperidin at 3,000mg daily for twelve weeks noted that supplementation was able to improve symptoms (assessed by ACR20; send point of a 20% improvement in symptoms^[191]) in three of nine subjects while placebo noted benefits in one out of ten subjects and there was a mild whole-group benefit with supplementation.^[29]

Higher than normal doses may offer mild therapeutic benefit to rheumatoid arthritis in humans

Hesperitin has estrogenic effects in MCF-7 cells at concentrations as low as 12.5µM, with 50-100µM of hesperitin being as effective as 10nM 17β-estradiol at inducing estrogenic signalling and hesperitin being slightly less effective than naringenin while both flavonanones acted on both estrogen receptor subsets;^[138] when incubated alongside 17β-estradiol, hesperitin (50µM) showed antiestrogenic properties thought to be due to competitive inhibition.^[138]

The concentration of hesperitin that is an antagonist to estrogen signalling (50µM) is significantly higher than that which is seen in serum following supplementation of hesperidin (2-4μM), and studies using hesperitin in this range have noted that both the nitric oxide signalling^[138] and the neuroprotective effects^[95] are dependent on estrogenic signalling.

Hesperitin possesses both estrogenic effects at low concentrations, and antiestrogenic effects at higher concentrations. Due to the concentrations expected in the body following oral ingestion, hesperitin is likely estrogenic which mediates its circulatory and neuroprotective benefits

Hesperitin is also known to be an aromatase inhibitor with equal or lesser potency as apigenin in vitro^[67][69] but appears to be more biologically relevant following oral intake as in mice bearing breast cancer tumors (excessive estrogen levels from aromatase), 0.1-0.5% hesperitin in the diet has reduced circulating estrogen levels in serum to control levels.^[69] This study also noted a failure for hesperidin to alter uterine weight (indicative of changes in estrogenicity), suggesting no net effect relative to control.

The overall estrogenicity of hesperitin in the body following oral administration is not fully clear at this moment in time, since while it has shown dependency on estrogenic signalling in vitro there are limited studies assessing how it influences circulating estrogen and whole-body estrogen-like effects

When investigating the phenolics found in oranges at their relevant concentrations, hesperidin (10.2μM in vitro) appeared to have synergism with myricetin (0.01mg/100g orange weight; 786nM in vitro), chlorogenic acid (0.19mg/100g; 10.7μM), and naringenin (7.1mg/100g; 2.61μM) when evaluated by ORAC.^[192] It seems that the combination of hesperidin and naringenin was further synergistic with all tested phenolics (myricetin, chlorogenic acid, p-coumaric acid, quercetin, and luteolin),^[192] and oddly myricetin and naringenin were antagonistic unless in the presence of hesperidin.^[192]

In vitro, hesperidin appears to be synergistic with other phenolic compounds found in oranges

In spontaneously hypertensive rats given hesperidin at 50mg/kg daily for eight weeks, there is a reduction in urinary 8-OHdG (biomarker of oxidative DNA damage) that does not occur in normotensive rats given hesperitin.^[142] This is also seen in rats given the chemotherapteutic cisplatin, where oxidative damage is reduced when cisplatin is preceded with a week of 100-200mg/kg hesperidin.^[193]

During diabetic retinopathy, it is known that the retina loses thickness and becomes more permeable to molecules in the blood. This appears to be in part due to both VEGF^[194] and diacylglyceride (DAG;^[195] since VEGF acts on its receptor to release DAG^[196]) influencing a protein known as PKCβ that mediates a loss of membrane integrity.^[197] These proteins are higher than normal the eyes of diabetics,^[198] and 200mg/kg hesperidin to diabetic rats for twelve weeks is able to partially attenuate the protein levels of VEGF and PKCβ.^[150]

Possibly related ot the above, 100-200mg/kg hesperidin to diabetic rats for twelve weeks reduces barrier breakdown (34.7-48.1%) and preserves retinal thickness with a potency comparable to dobesilate (42.3%)^[149] which has been noted elsewhere.^[150] This reduction in barrier breakdown is associated with a reduction in inflammatory biomarkers (ICAM-1 and TNF-α) as well as AGE formation and aldose reductase activity.^[149]

Hesperidin intake in diabetic rats appears to significantly but not fully reduce levels of the growth factors VEGF and PKCβ, and it is thought that the reduction in signalling (from VEGF towards PKCβ) causes a protective effect on the retinal membrane and reduces the progression of diabetic retinopathy

Hesperitin has been noted to have an mild inhibitory effect on the growth of helicobacter pylori.^[199]

In isolated enteroendocrine cells (STC-1), the aglycone hesperitin was able to induce secretion of cholecystokinin (CCK) with an EC₅₀ value of 50µM which is thought to be due to acting on TRPA1 and causing calcium influx in the cell; hesperidin was inactive in stimulating CCK release.^[200]

Uncertain influences on CCK release as, despite the higher concentration being feasible in the intestines, it aglycone that is not normally present was active while the aglycone (hesperidin) was not

Neither hesperitin nor hesperidin have appreciable inhibitory actions against common strains of colonic microflora (MIC values of 250 or greater).^[201]

Neither form appear to hinder intestinal microflora

Following irradiation, 50-100mg/kg oral ingestion of hesperidin for one week after irradiation therapy has been noted to reduce the elevation of liver enzymes and reduce lipid peroxidation to near normal levels^[202] which has been noted elsewhere.^[203]

In rats adminsitered the liver toxin TCDD, 50mg/kg hesperidin daily alongside the TCDD was able to attenuate the oxidative and inflammatory changes which were thought to underlie the protective effects on the organ.^[204]

Hesperidin possesses general protective effects against oxidative liver toxins, which are currently thought to be related to its antioxidant properties

500mg of G-Hesperidin daily in hyperlipidemics for 24 weeks is able to reduce circulating levels of the liver enzymes ALT, AST, and γ-GT only in those with high baseline triglycerides (150mg/dL) while having no effect otherwise.^[130]

A reduction in liver enzymes has been noted in hyperlipidemics given hesperidin supplementation

Hesperitin is thought to be beneficial for the lungs due to men with higher hesperitin/hesperidin intakes having lower mortality from cerebrovascular disease and lung cancer with lower incidences of asthma^[6] and that hesperitin possesses a selective PDE4 inhibitory effective in vitro.^[31]

Hesperidin (30-100μM/kg oral ingestion) two hours before and twice after an afterway hyperresponsiveness test in mice (for airway allergies) noted a mild attenuation of symptoms suggesting antiallergic effects, and this was assocaited with less infiltration of immune cells (leukocytes and macrophages) into lung tissue;^[205] and this has been replicated elsewhere with 10-30mg/kg (but not 5mg/kg) hesperidin an hour before stimulation.^[206] Since a variant (HDME) that was a more effective PDE inhibitor was more effective, implicating that as a mechanism of action.^[205]

Hesperidin appears to have acute anti-asthmatic properties in mice by reducing the responsiveness of the airways to an antigen

In rats given 100-200mg/kg hesperidin daily for a week, there are protective effects against subsequent injections of cisplatin with more efficacy in reducing lipid peroxidation (TBARS; a 95% attenuation at 100mg/kg and full normalization with a further 18% reduction at 200mg/kg) and protein carbonyls (79-84% normalization) rather than normalizing creatinine (30-53%) and BUN (34-57%);^[193] these changes were associated with full preservation of SOD and glutathione-S-transferase activity at both doses.^[193]

In control rats, 100-200mg/kg hesperidin trends to reduce oxidation but it does not reach significant levels.^[193]

In doxorubicin induced testicular toxicity, hesperidin (25-100mg/kg) daily give times weekly for five weeks is able to attenuate oxidative changes induced by doxorubicin and alongside that also normalized signs of toxicity such as abnormal sperm cells and testicular histopathology.^[207]

In a mouse model of androgen deficiency, supplementation of either hesperidin (0.5% of the diet) or G-hesperidin (0.7%) failed to reduce the atrophy of the testicles that occured from the androgen deficiency.^[165]

Estrogen is known to be created from testosterone via the aromatase enzyme (CYP19) and further hydroxylated via the CYP1B1 enzyme (into more potent estrogens, usually 4-hydroxylated^[208][209]) and since estrogenic signalling is known to accelerate some breast cancers,^[210] these enzymes are therapeutic targets for chemotherapy related to estrogen.^[211]

Hesperidin oral intake (1-5mg/kg of food) appears to reduce the weight of estrogen responsive tumors, with 0.5mg/kg being ineffective.^[69]

Rats fed a diet containing 1mg/kg hesperidin (or 1mg/kg Daflon conferring 100µg/kg hesperidin) after being injected with a colonic carcinogen noted that the hesperidin diet given for five weeks after the carcinogen was able to reduce the formation of aberrant crypt foci (indicative of colon carcinogenesis) by 60%, which was more effective than diosmin along (44%) but they appeared to be synergistic by reaching a 73% reduction.^[212]

Hesperidin may be able to significantly reduce colonic tumor formation when following a carcinogenic toxin, and it may be the active ingredient in oranges that is synergistic with moringa oleifera (not yet demonstrated with isolated hesperidin)

Hesperidin has been noted to noncompetitively inhibit tyrosine in B16 melanoma cells and HaCaT cells in the range of 125-500µg/mL, although with a potency less than the reference of 100µg/mL hydroquinone^[213][214] and an IC₅₀ value of 16.08mM.^[215] While it is thought to contribute to the skin whitening properties of oranges and tangerine extracts, another flavone (nobiletin) has a stronger inhibition with an IC₅₀ of 1.49mM and is competitive.^[215]

It has been noted to have whitening effects in vitro with a 1% hesperitin cream in a time-dependent manner over 29 days^[46] and in vivo when a microemulsion of hesperidin was topically applied for 30 days.^[216]

Hesperidin has moderately potent tyrosinase inhibiting properties, which may be relevant but have failed to surpass the reference drug of hydroquinone

Twice daily application of a solution containing 2% hesperidin (dissolved in 70% ethanol) to female mice for just under a week was able to accelerate the rate of skin barrier recovery (measured by water loss) relative to control after a stress was applied to the skin;^[217] this was due to stimulate skin cell proliferation and differentiation.^[217]

Hesperidin, but mostly Daflon (90% Diosmin and 10% Hesperidin) are used clinically to treat venous disorders. When compared to other venoprotective agents, Daflon (1,000mg daily) is less effective than Pycnogenol (150-300mg) over the course of eight weeks in patients with venous disorders as assessed by frequency and size of clinical benefits such as reductions in leg swelling and improvements in capillary function.^[1]

Hesperidin is a part of a therapy for CVI, but there is not much information on hesperidin by itself despite the combination therapy being well studied; despite that, it seems to be less potent than the other tested nutraceutical pycnogenol

In isolated PC12 cells incubated with the Alzheimer's protein fibril Aβ_25–35, hesperidin (10-50µM) is able to reduce fibril mediated toxicity by stabilizing the mitochondrial and reducing caspase release;^[218] the increase in VDAC1 phosphorylation seen with Aβ_25–35 (VDAC1 phosphorylation promotes apoptosis of the cell^[219]) which was thought to be due to activation of Akt (protects cells from fibrils^[220]) and GSK3β (prevents HXK from activating VDAC1^[221] noted with hesperidin.^[218]

Lower concentrations of hesperitin have also been noted to activate Akt (0.1-1µM) which may be more relevant to oral intake secondary to both TrkA and estrogen signalling^[95] and increased seladin-1 secondary to estrogen signalling,^[95] and the effects of higher hesperitin concentrations (50µM) has been noted to increase Akt by other mechanisms.^[95] Seladin-1 (Selective Alzheimer's Disease Indicator-1) is an estrogen responsive protein in neuroblastomas^[222][93] and mediates neuroprotection of cells via inducing Akt and antioxidant defenses.

Akt seems to be increased by two mechanisms, one of which occurs at too high of concentrations to be relevant to supplementation while the other is due to estrogenic signalling causing protective effects in cells. It is thought that Akt activation, and perhaps Selandin-1 induction, mediate protective effects in Alzheimer's Disease

Elsewhere in neuroblastoma cells, the dose-dependent inhibition of glucose uptake into these cells in the presence of Aβ_1-42 has been normalized with 1µM of either hesperitin or hesperidin with no further benefit at 20µM;^[223] this was thought to be due to preventing a downregulation of the insulin receptor, and was associated with less autophagy.^[223]

There may be a preservation of glucose uptake in neurons in the presence of hesperitin, which may be biologically relevant

In a rat model of 3-nitropropionic acid (3-NP) induced neurotoxicity, which is a rat model for Huntington's Disease,^[224] it was found that hesperidin at 100mg/kg orally alongside 3-NP was able to almost fully preserve the impairment to locomotion and prepulse inhibition despite no inherent effect on control rats; this was associated with significant suppression of iNOS induction in the cortex, hippocampus, and striatum as well as less lipid peroxidation (73-85% attenuation).^[225] Reduced nitric oxide production from less iNOS is thought to underlie the effects, since the protective effects can be attenuated with L-Arginine administration alongside 3-NP and hesperidin (50-100mg/kg).^[226]

It appears that the neuroprotective effects of hesperidin also extend to Huntington's Disease, and oral ingestion of reasonable doses of hesperidin exert pretty significant protective effects

One study has noted increased intestinal absorption of the carotenoids β-carotene and β-cryptoxanthin when in the presence of 250µM hesperidin or hesperitin (ex vivo assessment with Caco-2 cells) while said flavonoids were able to alleviate the suppressive effects of iron on the absorption of these carotenoids yet were blocked by vitamin C.^[227]

Hesperidin may increase intestinal absorption of carotenoids

Synephrine (p-synephrine) is an alkaloid found in high levels in the sour orange (Citrus aurantium) which seems to lack hesperidin and instead has a higher neohesperidin content; it is a metabolic stimulant, thought to be a successor to ephedrine from the plant ephedra sinicus.

50mg p-synephrine can increase metabolic rate by 65kcal relative to placebo (which noted a 30kcal decrease; measurements taken in the fasted state over 75 minutes), and the addition of 600mg naringenin increases this increase in metabolic rate to 129kcal and a further increase of 100mg hesperidin to both the aforementioned ingredients can again increase the metabolic rate to 183kcal;^[228] consuming a higher total level of hesperidin (1,000mg) with the aforementioned doses of p-synephrine and naringenin resulted in a lesser increase of the metabolic rate by 79kcal relative to control.^[228]

The orange flavanones seem to increase the ability of synephrine to increase the metabolic rate without any adverse effects on blood pressure, and while hesperidin seems active the above information is confounded with naringenin

Oral ingestion of 25mg/kg hesperidin (lowest effective dose for this purpose, and nonsignificantly better than doses in the 50-150mg/kg range^[229]) daily over 22 weeks in rats also given injections of 2.5mg/kg nicotine noted that coingestion of hesperidin was able to prevent an increase in liver enzymes (84-89% normalization on ALT, AST, and ALP) and also significantly attenuated the rise in other biomarkers of toxicity (tissue phospholipids, free fatty acids, and cholesterol) seen in the liver, lung, and kidneys of these rats.^[230] Antioxidant enzymes such as SOD, catalase, and glutathione peroxidase seem to be fully preserved relative to control.^[231][232]

There are also attenuations in the toxicity of nicotine as assessed by organ histology with most protection at the 25mg/kg dose,^[233] although some inflammation was still present despite not infiltrating damaged areas;^[230] it was later noted that hesperidin reduced MMP secretion from nicotine (involved in tissue infiltration) when given 25mg/kg hesperidin alongside nicotine^[231] with most preservation at 25mg/kg.^[229]

Low doses of hesperidin appear to be highly protective of prolonged nicotine toxicity when given to rats alongside the nicotine, and it seems that the lowest tested dose (25mg/kg in rats, or 4mg/kg in humans) is most effective