Phenolic acid

Phenolic acids or phenolcarboxylic acids^{[citation needed]} are phenolic compounds and types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important naturally occurring types of phenolic acids are hydroxybenzoic acids and hydroxycinnamic acids, which are derived from non-phenolic molecules of benzoic and cinnamic acid, respectively.

Phenolic acids can be found in many plant species. Their content in dried fruits can be high.

Natural phenols in horse grams (Macrotyloma uniflorum) are mostly phenolic acids, namely 3,4-dihydroxy benzoic, p-hydroxy benzoic, vanillic, caffeic, p-coumaric, ferulic, syringic, and sinapinic acids.^{[citation needed]}

Phenolic acids can be found in several mushroom-forming species of basidiomycetes. It is also a part of the humic substances, which are the major organic constituents of soil humus.^{[citation needed]}

Many phenolic acids can be found in human urine.

Immobilized Candida antarctica lipase can be used to catalyze the direct acetylation of flavonoids with phenolic acids.