caffeoyl

Caffeoyl is a chemical term used to designate the acyl group derived from caffeic acid that remains attached to another molecule through an ester or amide linkage. The caffeoyl moiety corresponds to the 3,4-dihydroxycinnamoyl fragment and is formed when caffeic acid participates in acyl transfer reactions during plant metabolism.

In plants, caffeoyl groups are widespread in hydroxycinnamic esters and related natural products. The best-known example is chlorogenic acid, a family of caffeoylquinic acids in which a caffeoyl unit is esterified to quinic acid. Caffeoyl groups also occur in other esterified phenolics such as caffeoyl tartaric and caffeoyl shikimate derivatives, and as components of broader polyphenolic compounds that contribute to plant defense and texture.

Biosynthetically, caffeoyl transfer is catalyzed by hydroxycinnamoyl transferases, which move the caffeoyl moiety from donors such as caffeoyl-CoA to various acceptors. These reactions link caffeic acid derivatives into the phenylpropanoid pathway, a central route for producing lignin precursors and a wide range of plant polyphenols.

In nutrition and pharmacology, caffeoyl-containing compounds commonly exhibit antioxidant activity and influence the sensory properties of foods. Chlorogenic acids, prominent caffeoyl esters in coffee and many fruits, are among the most studied caffeoyl derivatives for their dietary significance and potential health effects.