page_title: Caffeic acid
section_title: Biosynthesis
hierarchical_section_title: Caffeic acid / Metabolism / Biosynthesis
caption_attribution_description: English: structure of caffeic acid as an intermediate
context_page_description: 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.
context_section_description: 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.
caption: In plants, caffeic acid (middle) is formed from 4-hydroxycinnamic acid (left) and is transformed to ferulic acid.
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