Kaempferol

Last Updated: September 28, 2022

Kaempferol is one of the bioflavonoids that is present in high levels in cruciferous vegetables, and may mediate some of the bioactivities of these plants. It appears to hold anti-cancer potential.

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1.

Sources and Structure

1.1

Sources

Kaempferol, as a polyphenol, is present in many compounds. Common sources include:

  • Apples
  • Citris Fruits
  • Grapes and red wine
  • Onions and leeks
  • Tea (camellia sinensis)
  • Ginkgo Bilboa and St.Johns Wort
  • Nymphaea odorata[1]
  • Alpinia officinarum hance, or Galangal Extract[2]
  • Hedyotis verticillata (Source of kaempferitrin, kaempferol's rhamnoside sugar form)
  • Red beans and pinto beans (husk)[3] generally the species of bean Phaseolus Vulgaris.[4]

2.

Pharmacology

2.1

Absorption

The bioavailability of an oral load of kaempferol appears to be about 2% relative to an IV injection,[5] with most detectable molecules becoming quercetin, conjugated kaempferol, or isorhamnetin (3-O' methylated Quercetin).

About 3-4% of an oral dose of kaempferol (after 100mg/kg ingestion) appears to be excreted in the urine as free kaempferol.[5] The majority of the urinary metabolites appear to be glucuronides.

2.2

Serum

After a 1mg/kg bodyweight dose of Kaempferol in rats, a Cmax of 2.04+/-0.8nM was reached in serum after 30 minutes.[6] Higher doses have a slightly delated max peak at 60-90 minutes.[5] Approximately half of orally ingested Kaempferol is removed from the serum 4 hours after ingestion, and no free Kaempferol can be detected 6 hours even after a 250mg/kg bodyweight dose.[5]

In bone cells, the Cmax of Kaempferol is 0.684nM after 90 minutes.[6]

Chronic feeding (at 5mg/kg bodyweight) results in levels of 0.311nM after 4 weeks and 0.838nM after 12 weeks in rats.[6]

2.3

Interactions with P450

The liver appears to be more readily active on kaempferol than do the intestines, as assessed by a higher Vmax.[5] This was paired with a lower Km for hepatic microsomes relative to intestinal, suggesting more importance for the liver in the P450 metabolism of kaempferol.

Metabolic clearance via UDPGA conjugation appears to happen more readily than does Phase I oxidation.[5] When kaempferol undergoes Phase I oxidation, it becomes Quercetin,[7][5] and when it gets conjugated kaempferol becomes primarily Kaempferol-7O-glucuronide[8][9] although up to four glucuronides have been noted, including Astragalin (Kaempferol-3O-glucoside).[5] Glucuronidation is primarily undertaken by UGT1A3 and UGT1A9.[8]

3.

Neurology

3.1

Neurooxidation

Kaempferol possesses the ability to block the enzyme NAPDH oxidase (NOX), and act as a neuroprotectant against degeneration processes mediated by the NOX enzyme, [10] such as 4-HNE, a product created from lipid peroxidation of cellular membranes[10] and Advanced Glycemic End-products at an oral dose of 2-4mg/kg bodyweight in rats.[11]

4.

Interactions with Glucose Metabolism

4.1

Glucose Uptake

Kaempferol, possibly through the metabolite kaempferol 3-neohesperidoside, may increase glucose uptake into myocytes via processes mediated by phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) pathways[12][13] and has been suspected as being as potent as insulin in this regard.[14]

5.

Skeletal and Joint Health

5.1

Osteoblasts

Similar to myricetin, Kaempferol prevents against oxidation in in vitro bone cells and may exert anti-osteoporotic effects.[15]

6.

Fat Mass and Obesity

6.1

Adipogenesis

Kaempferol's inhibitory activity on Fatty Acid Synthase(FASN), the sole enzyme responsible for de novo lipogenesis, is via acting as an inhibitor of the FASN cascade, which uses the two substrate malonyl-CoA and acetyl-Coa along with NAPDH to ultimately produce palmitate.[16] Out of tested polyphenols, Kaempferol's inhibition of FASN was more potent than that of Green Tea Catechins, Apigenin and Taxifolin but less than that of quercetin and luteolin, of which the latter was the most inhibitory.[16]

Kaempferol may inhibit they fatty acid synthase enzyme associated with production of fatty acids from glucose

Kaempferol (as well as Quercetin) are able to inhibit PPARγ activation of adipogenesis by rosiglitazone and other endogenous ligands by having high affinity to the receptor but low potency to activate it.[17] Kaempferol appeared to activate PPARγ at most of 45% relative to rosiglitazone whilst Quercetin maxed at 20%, and neither induced adipocyte differentiation at concentrations ranging from 5-50µM.

Over the long term, Kaempferol may reduce adipocyte formation by causing its stem cell (bone marrow cells) to favor osteogenesis (bone forming) rather than fat cell forming.[6]

Possible inhibition of PPARγ induced by other agonists thereof

6.2

Glucose Uptake

Kaempferol is able to increase glucose uptake into a lab model of immortal adipocytes (3T3-L1), which suggests it may be able to reduce serum glucose levels and act as an anti-diabetic agent.[17] It works with insulin, and has no effect without insulin stimulation.

7.

Interactions with Hormones

7.1

Estrogen

Kaempferol appears to have some affinity for the alpha subset of the estrogen receptor (ERα) with an IC50 of 8.2µM[18] and also appears to have affinity for the beta subset of the estrogen receptor (ERβ) with an IC50 in the range of 50pM to 50µM[18][19] which appears to be comparable or slightly less than some other flavonoids (8-prenylnaringenin[20] and apigenin[19]) and significantly less than the soy isoflavones genistein (0.025-0.09), daidzein (0.1-1.20) and the S-equol metabolite (16-110pM).[21]

8.

Interactions with Cancer Metabolism

8.1

Mechanisms

Vicariously through its inhibitory effects on the FASN enzyme, Kaempferol shows promise in being able to inhibit certain types of cancer from developing. This is suspected to be due to a correlation between FASN activity being upregulated in cancer cells (due to a possible need for excess fatty acids for cell membrance production) and an apparent cytotoxic effect noted in cancer cells (but not normal cells) when the FASN precursor, Malonyl-CoA, hits supra-physiological levels. (Although other mechanisms are still under investigation)[22][23]

9.

Nutrient-Nutrient Interactions

9.1

Iron

When in the hull of red and pinto beans, free kaempferol (but not the glycoside) seems to inhibit iron absorption.[3] The addition of Ascorbic Acid (Vitamin C) did not increase bioavailability, and the inhibitory effect of kaempferol ranged from 15.5%-62.8% with concentrations of 40-1000uM, with inhibition potential as low as 0.37mM.[24]

Quercetin appeared to have a larger inhibition effect than did Kaempferol.[3] These inhibitory effects may be related to Kaempferol and Quercetin's ability to chelate metals by forming complexes.

The above interactions are behind the general idea of white beans, or foods low in flavonoid content, in having more bioavailable iron despite lower iron contents.[3][25]

References
1.^Zhang Z, ElSohly HN, Li XC, Khan SI, Broedel SE Jr, Raulli RE, Cihlar RL, Burandt C, Walker LAPhenolic compounds from Nymphaea odorataJ Nat Prod.(2003 Apr)
4.^Beninger CW, Hosfield GL, Nair MGFlavonol glycosides from the seed coat of a new manteca-type dry bean (Phaseolus vulgaris L.J Agric Food Chem.(1999 Jan)
5.^Barve A, Chen C, Hebbar V, Desiderio J, Saw CL, Kong ANMetabolism, oral bioavailability and pharmacokinetics of chemopreventive kaempferol in ratsBiopharm Drug Dispos.(2009 Oct)
6.^Trivedi R, Kumar S, Kumar A, Siddiqui JA, Swarnkar G, Gupta V, Kendurker A, Dwivedi AK, Romero JR, Chattopadhyay NKaempferol has osteogenic effect in ovariectomized adult Sprague-Dawley ratsMol Cell Endocrinol.(2008 Jul 16)
7.^Nielsen SE, Breinholt V, Justesen U, Cornett C, Dragsted LOIn vitro biotransformation of flavonoids by rat liver microsomesXenobiotica.(1998 Apr)
8.^Chen Y, Xie S, Chen S, Zeng SGlucuronidation of flavonoids by recombinant UGT1A3 and UGT1A9Biochem Pharmacol.(2008 Aug 1)
10.^Jang YJ, Kim J, Shim J, Kim J, Byun S, Oak MH, Lee KW, Lee HJKaempferol attenuates 4-hydroxynonenal-induced apoptosis in PC12 cells by directly inhibiting NADPH oxidaseJ Pharmacol Exp Ther.(2011 Jun)
12.^Zanatta L, Rosso A, Folador P, Figueiredo MS, Pizzolatti MG, Leite LD, Silva FRInsulinomimetic effect of kaempferol 3-neohesperidoside on the rat soleus muscleJ Nat Prod.(2008 Apr)
13.^Cazarolli LH, Folador P, Pizzolatti MG, Mena Barreto Silva FRSignaling pathways of kaempferol-3-neohesperidoside in glycogen synthesis in rat soleus muscleBiochimie.(2009 Jul)
14.^Jorge AP, Horst H, de Sousa E, Pizzolatti MG, Silva FRInsulinomimetic effects of kaempferitrin on glycaemia and on 14C-glucose uptake in rat soleus muscleChem Biol Interact.(2004 Oct 15)
15.^Suh KS, Choi EM, Kwon M, Chon S, Oh S, Woo JT, Kim SW, Kim JW, Kim YSKaempferol attenuates 2-deoxy-d-ribose-induced oxidative cell damage in MC3T3-E1 osteoblastic cellsBiol Pharm Bull.(2009 Apr)
20.^Milligan SR, Kalita JC, Heyerick A, Rong H, De Cooman L, De Keukeleire DIdentification of a potent phytoestrogen in hops (Humulus lupulus L.) and beerJ Clin Endocrinol Metab.(1999 Jun)
21.^Hajirahimkhan A, Dietz BM, Bolton JLBotanical modulation of menopausal symptoms: mechanisms of actionPlanta Med.(2013 May)
23.^Marfe G, Tafani M, Indelicato M, Sinibaldi-Salimei P, Reali V, Pucci B, Fini M, Russo MAKaempferol induces apoptosis in two different cell lines via Akt inactivation, Bax and SIRT3 activation, and mitochondrial dysfunctionJ Cell Biochem.(2009 Mar 1)