Rosmarinic acid is a fundamental compound of Rosmarinus officinalis. In this work, the intrinsic prooxidant (generation of H2O2 and free radicals by the action of peroxidase) and antioxidant (consumption of H2O2 and free radicals) properties of rosmarinic acid are characterized. In addition, its melanogenic prooxidant activity is characterized as it acts as a substrate of polyphenol oxidase to generate o-quinones, and its antimelanogenic and, so, antioxidant activity as it carries out the suicide inactivation of polyphenol oxidase. The balance between its pro- and antioxidant activities demonstrates that rosmarinic acid can be considered as a net antioxidant.


Antioxidants prevent oxidative damage by modulating the oxidative status of cells. The present results indicated that rosmarinic acid is an antioxidant and can act as scavenger of free radicals in biological systems, and could therefore provide health benefits to consumers. Moreover, rosmarinic acid can act as a suicide substrate of polyphenol oxidase and can inhibit the enzymatic browning of vegetables and fruits and melanogenesis in mammals.