Mercusic acid is a naturally occurring organic compound classified as a diterpenoid with the molecular formula . The acid features a labdane skeleton with exocyclic double bond at C8(17) and carboxylic groups at C15 and C19.
Mercusic acid was obtained from rosin of Pinus merkusii, a conifer native to Southeast Asia, hence the name. The acid is also found in such taxons as Brickellia glomerata, Cryptomeria japonica, Dicranopteris linearis, Juniperus formosana, Pinus yunnanensis, Cupressus sempervirens, among others.
Pine resin acids generally deter pests and pathogens. As part of oleoresin, mercusic acid acts as a chemical defense against herbivores, fungi, and bacteria via antimicrobial and antioxidative properties.
Natural resin acids present in rosin of Pinus species, including isopimaric acid, mercusic acid, neoabietic acid, dehydroabietic acid, and podocarpic acid, have been studied for their possible inhibitory effects on EpsteinâÂÂBarr virus. The acid is also known for its cancer chemopreventive activity.