Caffeic acid

Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is a key intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues. Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is a key intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues. Caffeic acid can be found in the bark of Eucalyptus globulus and the herb Dipsacus asperoides. It can also be found in the freshwater fern Salvinia molesta and in the mushroom Phellinus linteus. Caffeic acid is found at a very modest level in coffee, at 0.03 mg per 100 ml. It is one of the main natural phenols in argan oil. It is found at a high level in some herbs, especially thyme, sage and spearmint (at about 20 mg per 100 g), at high levels in spices, especially Ceylon cinnamon and star anise (at about 22 mg per 100 g), found at fairly high level in sunflower seeds (8 mg per 100 g), and at modest levels in red wine (1.88 mg per 100 ml) and in apple sauce, apricots and prunes (at about 1 mg per 100 g). It occurs at high levels in black chokeberry (141 mg per 100 g) and in fairly high level in lingonberry (6 mg per 100 g). It is also quite high in the South American herb yerba mate (150 mg per 100 g based on thin layer chromatography densiometry and HPLC ). It is also found in barley grain, and in rye grain. Caffeic acid, which is unrelated to caffeine, is biosynthesized by hydroxylation of coumaroyl ester of quinic acid (esterified through a side chain alcohol). This hydroxylation produces the caffeic acid ester of shikimic acid, which converts to chlorogenic acid. It is the precursor to ferulic acid, coniferyl alcohol, and sinapyl alcohol, all of which are significant building blocks in lignin. The transformation to ferulic acid is catalyzed by the enzyme caffeate O-methyltransferase. Caffeic acid and its derivative caffeic acid phenethyl ester (CAPE) are produced in many kinds of plants. Dihydroxyphenylalanine ammonia-lyase was presumed to use 3,4-dihydroxy-L-phenylalanine (L-DOPA) to produce trans-caffeate and NH3. However, the EC number for this purported enzyme was deleted in 2007, as no evidence has emerged for its existence. Caffeate O-methyltransferase is an enzyme responsible for the transformation of caffeic acid into ferulic acid.