Rosmarinic acid is a naturally occurring polyphenolic compound widely found in various Lamiaceae plants such as rosemary, sage, mint, and basil. Chemically, it is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is considered a natural, highly efficient, and well-stable antioxidant and a green food additive. It exhibits low toxicity and is generally considered safe. In terms of solubility, it is slightly soluble in water but readily soluble in alcohols and oils.
Research indicates that rosmarinic acid has a strong effect in scavenging free radicals, and its antioxidant activity is stronger than that of Vitamin E. It also possesses broad-spectrum antimicrobial, antiviral, anti-inflammatory, anti-tumour, anti-platelet aggregation, antithrombotic, antiangiogenic, and antipsychotic properties, as well as the function of fighting neurodegenerative diseases.