Phydroxycinnamic

Phydroxycinnamic, commonly called p-hydroxycinnamic acid or p-coumaric acid, is an organic compound in the hydroxycinnamic acid family. It features a cinnamic acid skeleton, a phenylpropene carboxylic acid, with a hydroxyl group attached at the para position of the aromatic ring. Its chemical formula is C9H8O3. It is typically encountered as a free acid or in esterified forms in plants.

Occurrence and biosynthesis: It is widespread in plants and serves as a key intermediate in the phenylpropanoid pathway. In plants, phenylalanine ammonia-lyase converts phenylalanine to cinnamic acid, which is hydroxylated at the para position by cinnamate 4-hydroxylase to yield p-hydroxycinnamic acid. It can be activated to p-coumaroyl-CoA and then channeled into the biosynthesis of lignin, flavonoids, stilbenes, and other phenolic metabolites. The compound also occurs as glycosides or esters in plant tissues and can be liberated by hydrolysis.

Properties and applications: It is a weak acid with limited water solubility and greater solubility in organic solvents. The molecule is used as a chemical intermediate in the synthesis of perfumes, flavors, pharmaceuticals, and polymer precursors. In addition, p-hydroxycinnamic acid and its derivatives are studied for antioxidant activity and potential health effects, though typical dietary effects are modest.

Related compounds: Related hydroxycinnamic acids include caffeic acid (3,4-dihydroxycinnamic acid), ferulic acid (4-hydroxy-3-methoxycinnamic acid), and sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid).