Para Coumaric Acid (pCA)

p-Coumaric acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers of coumaric acid—o-coumaric acid, m-coumaric acid, and p-coumaric acid—that differ by the position of the hydroxy substitution of the phenyl group. p-Coumaric acid is the most abundant isomer of the three in nature. p-Coumaric acid exists in two forms trans-p-coumaric acid and cis-p-coumaric acid. It is a crystalline solid that is slightly soluble in water, but well soluble in ethanol and diethyl ether. Together with sinapyl alcohol and coniferyl alcohols, p-coumaric acid is a major component of lignin. p-Coumaric acid is the precursor of 4-ethylphenol produced by the yeast Brettanomyces in wine. The yeast converts this to 4-vinylphenol via the enzyme cinnamate decarboxylase. p-Coumaric acid has antioxidant properties and is believed to reduce the risk of stomach cancer by reducing the formation of carcinogenic nitrosamines.