Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

, found in a variety of plants and plant-derived foods including

kale Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a hea ...

bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...

s, tea,

spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to central and western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common edible vegetable consumed either f ...

, and

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cla ...

. Kaempferol is a yellow crystalline solid with a melting point of . It is slightly soluble in water and highly soluble in hot

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

, ethers, and DMSO. Kaempferol is named for 17th-century German naturalist

Engelbert Kaempfer Engelbert Kaempfer (16 September 16512 November 1716) was a German naturalist, physician, explorer and writer known for his tour of Russia, Persia, India, Southeast Asia, and Japan between 1683 and 1693. He wrote two books about his travels. '' ...

.Kaempferol
at

Merriam-Webster Merriam-Webster, Inc. is an American company that publishes reference books and is especially known for its dictionaries. It is the oldest dictionary publisher in the United States. In 1831, George and Charles Merriam founded the company as ...

.com; retrieved October 20, 2017

Natural occurrence

Kaempferol is a secondary metabolite found in many plants, plant-derived foods, and traditional medicines. Its flavor is considered bitter.

In plants and food

Kaempferol is common in

Pteridophyta A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Ferns ...

Pinophyta Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

, and

Angiospermae Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

. Within Pteridophyta and Pinophyta, kaempferol has been found in diverse families. Kaempferol has also been identified in

Dicotyledons The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

and

Monocotyledons Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...

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 ''Aloe vera'' () is a succulent plant species of the genus '' Aloe''. It is widely distributed, and is considered an invasive species in many world regions. An evergreen perennial, it originates from the Arabian Peninsula, but grows wild in t ...

'', ''

Coccinia grandis ''Coccinia grandis'', the ivy gourd, also known as scarlet gourd, tindora and kowai fruit, is a tropical vine. It grows primarily in tropical climates and is commonly found in the Indian states, where it forms a part of the local cuisine. ''Coc ...

'', '' 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.

Biosynthesis

The biosynthesis of kaempferol occurs in four major steps: *

Phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amin ...

is converted into

4-coumaroyl-CoA Coumaroyl-coenzyme A is the thioester of coenzyme-A and coumaric acid. Coumaroyl-coenzyme A is a central intermediate in the biosynthesis of myriad natural products found in plants. These products include lignols (precursors to lignin and ligno ...

*4-coumaroyl-CoA combines with three molecules of

malonyl-coA Malonyl-CoA is a coenzyme A derivative of malonic acid. Functions It plays a key role in chain elongation in fatty acid biosynthesis and polyketide biosynthesis. Fatty acid biosynthesis Malonyl-CoA provides 2-carbon units to fatty acids and com ...

to form

naringenin chalcone Naringenin chalcone is a common chalconoid (or chalcone, not to be confused with the compound chalcone). It is synthesized from 4-coumaroyl-CoA and malonyl-CoA by chalcone synthase (CHS), a key enzyme in the phenylpropanoid pathway. Naringenin ...

(tetrahydroxychalcone) through the action of the enzyme chalcone synthase *Naringenin chalcone is converted to

naringenin Naringenin is a flavorless, colorless flavanone, a type of flavonoid. It is the predominant flavanone in grapefruit, and is found in a variety of fruits and herbs. Structure Naringenin has the skeleton structure of a flavanone with three hydro ...

and then a hydroxyl group is added to form

dihydrokaempferol Aromadendrin (aromodendrin or dihydrokaempferol) is a flavanonol, a type of flavonoid. It can be found in the wood of ''Pinus sibirica''. Metabolism The enzyme dihydrokaempferol 4-reductase uses ''cis''-3,4-leucopelargonidin and NADP+ to prod ...

*Dihydrokaempferol has a double bond introduced into it to form kaempferol 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 The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosymbiotic cyan ...

, and is the entry to the biosynthesis of phenylpropanoids. The

phenylpropanoid pathway The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. Their name is derived from the six-carbon, aromatic phenyl group and the three-carbon propene tail of ...

is the pathway that converts phenylalanine into tetrahydroxychalcone. Flavonols, including kaempferol, are products of this pathway.

Notes

External links

*
Flavonoid composition of tea: Comparison of black and green teas
{{Purinergics Antidepressants Xanthine oxidase inhibitors Flavonoid antioxidants Phytoestrogens Progestogens