1. Phenolic acids or phenolcarboxylic acids 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. == Occurrences == 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. 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. Many phenolic acids can be found in human urine. == Chemistry == Immobilized Candida... from wikipedia.org