kaempferol

Kaempferol is a natural flavonol, 3,4',5,7-tetrahydroxyflavone (C15H10O6). It is a polyphenolic compound found in many edible plants and plant foods.

Occurrence and sources: Kaempferol is present in onions, kale, tea, broccoli, spinach, and beans, with apples and grapes also containing notable amounts. Levels vary by species, variety, and processing. In foods it is usually found as glycosides such as kaempferol-3-O-glucoside (astragalin) and kaempferol-7-O-glucoside; during digestion these glycosides are hydrolyzed to the aglycone.

Biosynthesis: In plants, kaempferol is produced through the flavonoid biosynthetic pathway, derived from phenylalanine via cinnamate and malonyl-CoA and catalyzed by enzymes such as chalcone synthase. It is synthesized by a broad range of plant species and serves various physiological roles in plants.

Biological activities: Kaempferol exhibits antioxidant and anti-inflammatory properties in laboratory studies. It can modulate signaling pathways including NF-kB and MAPK and may inhibit pro-inflammatory enzymes. In preclinical (cell culture and animal) studies, kaempferol has shown potential anti-cancer, neuroprotective, and cardioprotective effects, but clinical evidence in humans remains limited.

Pharmacokinetics: Oral bioavailability is generally low due to limited absorption and extensive metabolism. Glycosides are often hydrolyzed by intestinal microbiota before absorption, after which kaempferol forms glucuronide or sulfate conjugates and is excreted in urine.

Research and applications: Kaempferol is studied as a component of dietary phytochemicals with potential health benefits. It is not approved as a drug, and dietary intake varies with diet and food preparation.