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 including kale, beans, tea, spinach and broccoli. Kaempferol is a yellow crystalline solid with a melting point of . It is slightly soluble in water and highly soluble in hot ethanol, ethers, and DMSO. Kaempferol is named for 17th-century German naturalist Engelbert Kaempfer.
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, 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.
Biosynthesis.
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.