Kaempferol

Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods. Kaempferol is a yellow crystalline solid with a melting point of 276–278 °C (529–532 °F). It is slightly soluble in water and highly soluble in hot ethanol, ethers, and DMSO. Kaempferol acts as an antioxidant by reducing oxidative stress. Many studies suggest that consuming kaempferol may reduce the risk of various cancers, and it is currently under consideration as a possible cancer treatment. It is named for 17th-century German naturalist Engelbert Kaempfer. Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods. Kaempferol is a yellow crystalline solid with a melting point of 276–278 °C (529–532 °F). It is slightly soluble in water and highly soluble in hot ethanol, ethers, and DMSO. Kaempferol acts as an antioxidant by reducing oxidative stress. Many studies suggest that consuming kaempferol may reduce the risk of various cancers, and it is currently under consideration as a possible cancer treatment. It is named for 17th-century German naturalist Engelbert Kaempfer. Kaempferol is a secondary metabolite found in many plants, plant-derived foods, and traditional medicines. Its flavor is considered bitter. Kaempferol is common in Pteridophyta, Pinophyta and Angiospermae. Within Pteridophyta and Pinophyta, kaempferol has been found in diverse families. Kaempferol has also been identified in both Dicotyledons and Monocotyledons of Angiosperms. The total average intake of flavonols and flavones in a normal diet is estimated as 23 mg/day, to which kaempferol contributes approximately 17%. Common foods that contain kaempferol include: apples, grapes, tomatoes, green tea, potatoes, onions, broccoli, Brussels sprouts, squash, cucumbers, lettuce, green beans, peaches, blackberries, raspberries, and spinach. Plants that are known to contain kaempferol include Aloe vera, Coccinia grandis, Cuscuta chinensis, Euphorbia pekinensis, Glycine max, Hypericum perforatum, Pinus sylvestris, Moringa oleifera, Rosmarinus officinalis, Sambucus nigra, and Toona sinensis, and Ilex. It also is present in endive. The biosynthesis of kaempferol occurs in four major steps: The amino acid phenylalanine is formed from the Shikimate pathway, which is the pathway that plants use in order to make aromatic amino acids. This pathway is located in the plant plastid, and is the entry to the biosynthesis of phenylpropanoids. The phenylpropanoid pathway is the pathway that converts phenylalanine into tetrahydroxychalcone. Flavonols, including kaempferol, are products of this pathway. Kaempferol is ingested as a glycoside, absorbed in the small intestine, usually by passive diffusion due to kaempferol’s lipophilicity, and metabolized in various areas of the body. In the small intestine, kaempferol is metabolized to glucuronides and sulfoconjugates by intestinal enzymes. It can also be metabolized by colon microflora which can hydrolyze the glycosides to aglycones or form simple phenolic compounds. These compounds can be absorbed or excreted. Kaempferol is also extensively metabolized in the liver to form glucurono-conjugated and sulfo-conjugated forms. These forms of kaempferol, and kaempferol itself, can then be excreted in urine. About 2.5% of kaempferol ingested is excreted as urine. Much of the rest of ingested kaempferol is present in the plasma and tissues in nanomolar concentrations. Numerous preclinical studies have shown kaempferol and some glycosides of kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anticancer, cardioprotective, neuroprotective, antidiabetic, antiosteoporotic, estrogenic/antiestrogenic, anxiolytic, analgesic, and antiallergic activities. In vitro studies along with some animal testing has demonstrated the wide range of potential anti-cancer properties of kaempferol. It has been shown in malignant cancer cells to interrupt cell growth, limit angiogenesis, induce apoptosis, and to reduce their available energy and ability to metastasize. Kaempferol has also been shown to reduce MMP-3 protein activity inferring potential ability to reduce metastasis.