1.1. Sources
Cnidium Monnieri appear to be a Traditional Chinese Medicine. The plant itself is referred to as Cnidium Monnieri, whereas the vertical root aspect is referred to as Rhizome Cnidii.[1] The fruits tend to be used in Traditional Chinese Medicine, where the seeds are referred to as She chuang zi[2] and has the Japanese name of Jashoshi. Cnidium fruits are traditionally used for anti-viral properties, skin rashes and breakouts, as pro-erectile agents (in men) and gynecoprotective (in women), anti-osteoporotic as well as anti-diabetic and sometimes anti-inflammatory. Infrequently, it is also said to be 'anti-aging' and to 'build up strength', highly vague claims.
1.2. Composition and Structure
Cnidium Monnieri contains:
Coumarin compounds such as Osthole (18.85-20.12mg/g dehydrated fruit) and Imperatorin (0.79-1.02mg/g dehydrated fruit)[2][3][4] as well as Xanthotoxin (Methoxsalen).[5] Isopimpinellin, and Bergapten have also been identified[6] Hydrated berries of Cnidii have concentrations around 1.67-2.88% osthole.[7]
Tetramethylpyrazine[8]
Furanocoumarins similar to Imperatorin, such as Cnidilin[9]
Sequiterpenes such as Torilin, Torilolone, and 1-hydroxytorilin[10]
Chromones such as Umtatin, cindimol, and karentin[11]
Daucosterol[5]
Terpenoids such as Alpha-Pinene, Camphene, and Limonene
Osthole is commonly seen as the primary active ingredient due to it being the most prominent courmarin derivative in Cnidium Monnieri,[2] and is a coumarin derivative compound. It's true chemical name is 7-methoxy-8{3-methylpent 2-enyl}coumarin, and its structure pictured below. The fruits tend to be used in Traditional Chinese Medicine, but the seeds of Cnidium Monnieri contains these bioactives as well.
Due to the additional pentacyclic ring on Imperatorin, that compound is seen as a furanocoumarin. Still a coumarin, but a further classification thereof.
Osthole exhibits low water solubility, which limits its absorption in isolation somewhat.[12]
Cnidium Monnieri tends to be seen as a vessel for the coumarin compounds similar in action to Osthole, seen as the main bioactive; the concentration of these compounds in the dried fruit can get quite high
It should be noted that Osthole has also been isolated in the plant Angelica Pubescens[13] and was first isolated from Peucedanum ostruthium from which it derives its name.[14] Cnidium Monnieri is merely a good source of Osthole and has its traditional usage to add to its marketing value.
1.3. Related herbs
Cnidium officinale Makino is a related herb used in traditional Chinese and Korean medicine as well, and has the name Cheong-gung in Korean.[1] This plant is known for its 'oriental' taste and scent, and containing a wide variety of volatile oils.[15]
Cnidium officinale Makino is a perennial plant from the family Umbelliferae and is medicinally used as a sedative and for the treatment of anemia, brain disease, and female genital inflammatory disease such as menstrual irregularity.[16][1]
Cnidium Officinale Makino contains:
Ferulic Acid (ethanolic extract of rhizome) at 0.69-1.65mg/g[1]
Chlorogenic Acid (ethanolic extract of rhizome) at 0.84-5.35mg/g[1]
The pthalides Senkynolide A and Z-ligustilide (ethanolic extract of rhizome) in the range of 0.32 (+/-0.02) to 1.14 (+/-0.06) for Senkyolide A and 0.74 (+/-0.04) to 4.39 (+/-0.31) for Z-ligustilide (median values for each, of a sample of 15 herbs, was 0.65 and 1.56; respectively). All values as mg/g.[1] Other pthalides are present, such as Senkyloide H and 6-hydroxy-7-methoxy-dihydroligustilide[17]
Falcarindiol (heptadeca-1,9(cis)-diene-4,6-diyne-3,8-ol)[17] and anti-inflammatory molecule with an IC50 value of 4.31 ± 5.22uM for inhibiting NO release from LPS-induced macrophages[17]
2.1. Absorption and Serum
After oral administration of 40mg/kg osthole to rats, the following values were obtained via cloud-point extraction; a Cmax of 2.72 ± 0.89ug/mL at a Tmax of 0.56 ± 0.18 hours, an AUC to infinity of 11.27 ± 2.63ug/h/mL and an AUC0-t of 10.49 ± 2.81ug/h/mL, with a half-life of 5.26 ± 1.67 hours.[18] The only parameter that significantly differed between oral and intravenous administration was the Tmax (significantly, 0.093 hours I.V) and slightly Cmax due to perfect bioavailability of injections; excretion kinetics were not measured in this study.[18] Using hollow fiber liquid phase microextraction + HPLC (touted to be more reliable than cloud-point[19]) 20mg/kg oral ingestion of osthole results in a Cmax of 366 ± 89ng/mL at a Tmax of 0.61 ± 0.09 hours, with an AUC0-t of 780 ± 585ng/h/mL of and a half-life of 4.94 ± 1.84 hours.[19]
As 40mg/kg oral administration had an AUC to infinity of 11.27 ± 2.63ug/h/mL and a Cmax of 2.72 ± 0.89ug/mL, and 8mg/kg injections have an AUC to infinity of 10.52 ± 2.34ug/h/mL and a Cmax of 4.35 ± 0.65ug/mL, it has an approximate bioavailability of 26.8% when administered in isolation to rats.[18] Bioavailability may be limited by metabolism, as it was demonstrated in vitro that up to 80% of osthol is metabolized within 20 minutes, 40% within 5 minutes of contact with intestinal cells, via phase I conjugation.[20] Osthole itself does have high permeability across intestinal cell membranes via passive diffusion,[20] and apical to basolateral has similar rates as basolateral to apical diffusion.[21] In support of the notion that passive diffusion is the mechanism of absorption, an MRP inhibitor had no effect on kinetics[21] and the diffusion does not seem highly temperature dependent (inactivation of transport enzymes).[20]
In isolation, Osthole appears to have moderate bioavailability (not an ideal number, but better than many compounds isolated from herbs) and a relatively quick Tmax, spiking in the blood in under an hour after oral consumption. Although one study noted micrograms (ug) and the other nanograms (ng), this disparity may be due to the analysis techniques
When the ethanolic extract of Fructus Cnidii is consumed (fruits, dehydrated and rinsed with ethanol twice; precipitate then ingested) 10g/kg of the extract (131mg/kg osthole total) fed to rats results in a similar Tmax (1 +/- 0.3 hours) and half-life (3.6 +/- 0.6 hours), an AUC to infinity of 3.55 ± 0.385ug/h/mL and a Cmax of 0.776 ± 0.069ug/mL.[22] When Osthole is consumed via the herb Libanotis buchtormensis, it has lesser absorption than isolated Osthole.[23]
Unlike a fruit like Evodia Rutaecarpa, consumption of Osthole via the ethanolic fruit extract does not seem to greatly enhance bioavailability of Osthole; it may, but consumption of the fruit does not appear to be critical
2.2. Metabolism
Metabolism via desmethylation (into O-desmethyl Osthole[20]) may be mediated via CYP2D6 or CYP3A4[24] but inhibition of CYP2D6 in vitro with Yohimbine fails to alter hepatic metabolism of Osthole.[25]|published=2009 Oct|authors=Zhang LF, Hu X, Wang P, Zhang L|journal=Yao Xue Xue Bao] Inhibition of CYP3A4 appears to prolong Osthole half-life in vitro,[25]|published=2009 Oct|authors=Zhang LF, Hu X, Wang P, Zhang L|journal=Yao Xue Xue Bao] despite the aforementioned metabolite being O-desmethylated and not N-desmethylated.[20] However, these in vitro results were contrasted with an in vivo rat study suggesting that hydroxylation, demethylation and hydrogenation of double bonds were the primary routes of metabolism during phase I.[26]
Low bioavailability of Osthole appears to be mediated mostly by excessive and quick Phase I metabolism, with various possible routes of metabolism
2.3. Clearance
A clearance rate of after 20mg/kg oral administration of 0.67 ± 0.15 mL/kg/h osthole has been noted.[19]
3.1. Fatty Liver
Osthole is able to reduce fatty liver induced by alcohol; in a study where mice were fed 52% of caloric intake as ethanol for 4 weeks and then given 10-40mg/kg Osthole for 6 weeks, Osthole was able to normalize alterations in CPT1A and CYP2E1 transcription rates (made abnormal with prolonged alcohol ingestion, and conducive to further fat buildup) and was able to decrease liver fat content in a rehabilitative manner.[27] These effects are also seen when the same dose of osthole is co-ingested,[28] and are attributed to anti-oxidant and anti-inflammatory mechansims,[27][28] although Osthole does appear to induce PPARa activation which can then reduce DGAT and HMG-CoA activity; a shift towards lipid mobilization rather than storage.[29] Minor dose-dependence is seen, with more Osthole exerting more protection but 10mg/kg seeming to be the most cost-effective dose.[27][28]
Benefit is also seen in diet-induced fatty liver, specifically milk-fat induced fatty liver.[30][31][32] The cause of fatty liver does not appear to be relevant, just having fatty acids present in the liver.
At least one study using 6 weeks of Osthole supplementation (10-40mg/kg) and 2 weeks of fatty-liver induced milk consumption noted that triglyceride content in liver tissue was even lower than control.[33]
Osthole, the active component of Cnidium Monnieri, appears to be able to reduce triglyceride levels in the liver (fatty liver) in both instances of alcohol-induced fatty liver and diet-induced fatty liver. No human studies, but several rat studies all noting benefit
The mechanism above on PPARa activation in alcohol induced fatty liver[29] is also seen with dietary fat-induced fatty liver (NAFLD),[31][32] Activation of PPARa can then later downregulate DGAT and CYP7A1, which are abnormally elevated during instances of fatty liver, and increase CPT1A activity, which is suppressed during fatty liver.[32]
An independent alternate mechanism is modulation of SREBP-1c/2 proteins,[33] as 10-40mg/kg bodyweight Osthole suppresses SREBP-1c and SREBP-2 mRNA in mice subject to fatty-liver diets by 36.6%–54.6% and 64.5%–107.7%, respectively,[33] with 40mg/kg Osthole able to normalize SREBP-2 relative to control.[33]
mRNA transcription rates of Fatty Acid Synthase are suppressed by 9.1%–38.7%, and the LDL receptor in the liver by 54.7%–78.9%, after ingestion of 10-40mg/kg Osthole in rats subject to fatty liver.[33] Whether this is secondary to SREBP modulation or PPARa activation is not known.
Two ultimate mechanisms are being investigated for their abilities to explain what is seen with Osthole, and both pathways seem catered to either getting fatty acids out of the liver or just eliminating the fatty acids by using them for energy
3.2. Protection
Cnidium Monnieri has been implicated in vitro human liver cells to protect cells from tacrine-induced toxicity, via the torilin components.[10] As assessed by EC50 values, Torilin and Torilolone appear to be 3.34-fold and 19.1-fold more effective than Silybin from Milk Thistle in protecting liver cells from Tacrine.[10]
3.3. Diabetes
Although Osthole (from Cnidium) is implicated as an AMPK activator which can reduce the effects of diabetes (See section on glucose metabolism), the reduction of fatty liver can also contribute to anti-diabetic effects.[34]
4.1. General
Osthole shows non-selective cytotoxicity in cancer cells, specifically that of the breast (MCF-7), lung (SK-LU-1), epidermal carcinoma (KB), and liver (HepG2).[5]
4.2. Breast Cancer
In vitro studies on MCF-7 and MDA-MB-231 cell lines suggest Osthole can inhibit breast cancer cell proliferation with IC50 values of 25.8uM and 30.2uM; respectively. A moderately potent inhibition.[14]
A possible mechanism of this cytotoxicity may be inhibition of fatty acid synthase (FASN), of which inhibition causes cytotocix buildup of precursors; Osthole shows cytotoxic preference in cells overexpressing HER2, which increases FASN activity.[35] This was downstream of inhibiting Akt/mTOR activation in breast cancer cells as HER2 mediates FASN via Akt/mTOR,[35] and Osthole shares this mechanism with Green Tea Catechins.[36] The FASN phenotype appears to be somewhat common in breast cancer,[37] perhaps up to 30% (as assessed by HER2).[38]
Inhibition of MMP2 has also been noted with osthole in vitro, which can help to explain how osthole may be able to suppress invasion and metastasis of breast cancer cells.[39] This ability is possibly tied into FASN inhibition, as HER2 overexpressing cells are commonly seen as being more prone to metastasis.[40]
Has potential as an anti-breast cancer agent, but has not been explored in vivo yet. Seems to act on Fatty Acid Synthase and Akt/mTOR similar to Green Tea Catechins, but no comparison of potency can be made
5Interactions with Neurology
5.1. Glutaminergic Signalling
In vitro with hippocampal cells, isolated osthole (a bioactive of Cnidium M.) has been shown to elevate Glutamate release from neurons during an action potential (AP) from 7.9±0.2nmol/mg per 5min (No Osthole) to 11.7±0.5nmol/mg per 5min (3uM Osthole, a 48.1% increase), without affecting basal glutamate release and these effects were also seen with Imperatorin, another bioactive.[4] This reaction was given an IC50 of 3.5uM (4.7uM for Imperatorin) and was concentration dependent.[4] The mechanism appears to be through facilitating Ca2+ influx into the neuron during AP, as 3uM Osthole increases the peak levels of Ca2+ from 138.3±3.1nM (AP, no Osthole) to 159.5±2.3nM (Osthole at 3uM) and appears to be via PKC activation, as phosphorylation of PKC is increased from 112.5+/-3.8% of baseline (AP, no Osthole) to 134.6+/-5% of baseline (3uM Osthole during AP).[4] Osthole does not appear to influence resting membrane potential.
In vivo studies looking at cGMP signalling also note enhanced glutaminergic signalling and noted increased accumulation of cGMP, a signalling molecule upstream of PKC.[41] Inhibition of the protein kinase cGMP acts upon (cGMP dependent protein kinase, or PKG) prevents the release of glutamate from osthole.[41]
Any activation of cGMP can cause the above effects, and incubation of neurons with Viagra (sildenafil) which can increase cGMP (by inhibiting PDE5) displaces Osthole's effects as they are already present;[41] Sildenafil and Osthole appear to be of similar efficacy, with an EC50 value of 5uM and 4uM respectively.[41][4] Two other cGMP activators were present, and also demonstrated a lack of additive effects with osthole.[41] These results suggest Osthole and Viagra act via similar mechanisms, but may not be additive or synergistic with each other.
Beyond increasing Ca2+ influx and the pre-axonal cGMP influences, Osthole (and Imperatorin) may also be able to increase exocytosis of glutaminergic vesicles, which is the ultimate event resulting in enhanced glutamate release.[42] This increased exocytosis of vesicles is caused by Ca2+ influx, and inhibition of said influx prevents its effects.[4]
The above hippocampal glutaminergic enhancement may be a mechanism behind Cnidium's pro-erectile effects (See section on Sexuality) as glutaminergic action in the hippocampus is linked to erections.[43][44] Glutamate or glutaminergic agonists injected into the hippocampus or hypothalamus induce erections, which in inhibited by antagonists of glutamate receptors; higher levels of glutamate are seen in cerebrospinal fluid and the hypothalamus during erections as well.[41]
Increases glutaminergic neurotransmission via increasing calcium influx into neurons during an action potential, this is due to increasing cGMP levels in the neuron. This may be localized to the hippocampus and some other areas, such as the hypothalamus
These mechanisms suggest it can enhance neural stimulation without, per se, being stimulatory on its own. However, this statement is conjecture
5.2. Sedation and GABAergic signalling
Osthole has been implicated in enhancing phenobarbitol-induced sedation, and negating the effects of caffeine hyper-exitability in animals.[45] Osthole does not appear to bind to the benzodiazepine binding site, as its effects are not inhibited by flumazenil at 1uM.[46]
When looking into possible mechanisms, Osthole appears to interact with GABA(A) receptors. Osthol, as well as Imperatorin and Cnidilin, appear to potentiate chloride current induced by GABA(A) activation by 273.6%±39.4% (Osthol), 109.8%±37.7% (Imperatorin) and 204.5%±33.2% (Cnidilin).[9] Only 100uM and 300uM were tested, with the previous values at 300uM; dose-dependence appear to occur.[9] These effects were seen with the α1β2γ2S GABA(A) subset, and Osthole appears to have an EC50 value of 14+/-1uM in this regard.[46]
When used by itself as an anti-allergic substance in rats (See Allergies section), Cnidium does not appear to cause sedation or reduce movement at doses ranging from 50-500mg/kg bodyweight.
5.3. Protective Effects
Cnidium has been suggest to, in rats, protect from reductions in spatial functioning that is the result of either ovariectomization or by scopolamine at 3-10mg/kg bodyweight oral ingestion.[47]
6Interactions with Glucose Metabolism
6.1. Skeletal Muscle
Osthole has been implicated in increasing AMPK-mediated glucose uptake into myocytes (both C2C12 and L6) in dose and time dependent manners, although tested mostly at 12.5-50uM[34] and also affects hepatocytes to a less potent extent.[34] Incubation of muscle cells with 12.5uM and 50uM increases glucose uptake via GLUT4 translocation induced by AMPK by 1.6 and 2-fold; respectively.[34] These effects on AMPK may be due to shifting the AMP:ATP ratio, as osthole seems to deplete ATP and elevate relative amounts of AMP,[34] which is known to be the lead inducer of skeletal muscle AMPK.[48] Osthole was known to be anti-glycemic in vivo at 50mg/kg prior to the discovery of AMPK interactions,[49] and was mimicked in streptozotocin-induced diabetic mice at 100mg/kg osthole orally for 8 weeks.[34]
Osthole apparently may also phosphorylate (activate) Akt, and the downstream proteins of AS160 and GSK3; another mechanism by which GLUT4 may be increased.[34]
6.2. Adipose
AMPK may also be activated in the aforementioned manner in adipocytes, due to an increased differentiation rate of adipocytes seen in rats when orally fed 50mg/kg Osthole.[49] This is an anti-diabetic effect due to more cells consuming glucose.
6.3. Hepatic
Osthole may confer anti-diabetic effects in persons with fatty liver, secondary to its ability to reduce fatty liver build-up. 5 and 10mg/kg osthole, delivered orally, is able to reduce liver levels of fatty acids and triglycerides secondary to anti-inflammatory effects, which improves insulin sensitivity in diet-induced obese animals.[50]
7Interactions with Obesity
7.1. PPARa/y
Osthol appears to be a mixed inducer of PPAR alpha and gamma activity,[32] which is one of the mechanisms by which it protects against fatty liver.[29] It was also thought to be a mechanism of Osthole's anti-diabetic effects,[49] but AMPK activation seems a more likely explanation for that.
PPARa and PPARy activation is a mechanism of fat loss for some supplements, initially seen with Conjugated Linoleic Acid and more effectively done by TTA. Thus Osthole holds potential as a fat loss agent.
Studies in rats that measure body weight note statistically insignificant reductions in body weight. When fed a diet that induces fatty liver, mice that normally gained 9.5% of their bodyweight had the gain reduced to 3.2-5.1% with no observed dose-dependence.[33]
Holds potential to be either a fat loss agent, or an anti-obesity agent (induce fat loss or prevent fat gain, respectively) but has not been studied for either claim yet
8Interactions with Sexuality
8.1. Erections
Cnidium Monnieri is, supposedly, a frequently prescribed herb among Chinese Medicine practitioners for male impotence. It has traditionally been used for treatment of male erections (or the lack thereof) alongside Epimedium Sagittatum (related to Horny Goat Weed) and the plant Semen Cuscutae.[51]
When examined in vitro on corpus cavernosum (penis wall) muscles, the bioactive ingredient Osthole appears to be able to cause muscular relaxation (pro-erectile) in a dose-dependent manner.[52] The mechanism may be via phosphodiesterase inhibition, as osthole appears to potentiate cGMP induced relaxation as well as nitric oxide.[52] These effects are common to all coumarins in Cnidium Monnieri, with Imperatorin being requiring the lowest concentration to be effective.[53]
There may also be central (brain) effects as well, due to the ability of osthole to induce glutaminergic neurotransmission (see Neurology section).
Not yet studied in humans, but has traditional usage of being an erection promoting herb in Traditional Chinese Medicine and appears to be active on both the penis tissues and the brain in similar manners to Viagra
9Interactions with Hormones
9.1. Testosterone
Osthole has once been implicated in increasing testosterone, as well as luteinizing hormone and FSH, in male castrated rats over 20 days.[54] It has not been investigated further than this.
9.2. Estrogen
When studied in ovariectomized rats (a research model for menopause), both 17β-estradiol (biologically active estrogen) injected at 30ug/kg and osthole orally administered at 9mg/kg were effective in alleviating bone loss. However, this study noted that osthole did not influence other parameters of estrogen metabolism, and may not exert these anti-osteoporotic benefits via estrogen metabolism.[55] The loss of uterine mass and weight gain that were attenuated with 17β-estradiol were not influenced by osthole.[55]
9.3. Progesterone
One study noted the pair of Angelicae Sinensis alongside Cnidium Monnieri was able to increase progesterone secretion from the corpus luteum in vitro.[56]
10.1. Airway
10.2. Skin
Cnidii Fructus (fruits of Cnidium) have traditionally been used orally as an anti-allergic substance; when testing a variety of traditional herbs (n=33 in total, 6 found to be effective) touted to suppress skin irritation, Cnidium appears to be the most effective in inhibiting substance-P induced itching behaviour in mice.[57]
Oral administration of 50-500mg/kg bodyweight of a Cnidium Monnieri ethanolic extract was demonstrated, in mice suffering from irritated skin (compound 48/80), to reduce scratching behaviour and thus exert an anti-pruritic effect.[58] These same effects have been seen after oral administration of Cnidium fruits in mice give Substance-P, another pro-scratching agent.[59] The bioactives appear to be Osthole and the related coumarins may also influence, as Isopimpinellin and Osthole (but not Imperatonin) showed benefit in isolation when tested against compound 48/80[58] but only Isopimpinellin was effective against substance-P.[59] When compared to diphenhydramine (active control) at 50mg/kg, Cnidium at 200mg/kg and 500mg/kg we not as effective in reducing scratching behavior, whereas Cnidium was able to exert 33.1-34.7% inhibition of scratching while diphenhydramine inhibited 89.3%.[58] There was no dose-dependence, and 50mg/kg appeared to not be significantly different than 200mg/kg and 500mg/kg.[58]
Coumarins, most likely Isopimpinellin, appear to be somewhat effective in reducing the sensation of itch when they are ingested orally as part of a diet or supplement regimen
Osthole and the coumarins have also been implicated in suppressing 'outbreaks' of contact dermatitis, topical inflammation, when administered orally at 200-500mg/kg bodyweight to mice.[60]
11Interactions with Heart and Blood Health
11.1. Cardiac Tissue
Osthole, a bioactive of Cnidium, is able to inhibit epinephrine-induced and caffeine-induced aortic constriction in a dose-dependent manner, at ranges tested from 40-200uM.[61] As it is partially inhibited by methylene blue and not affected by indomethacin, the mechanism by which Osthole can induce relaxation appears to be via acting as a calcium-channel blocker and increasing accumulation of cGMP.[61]
