Rosmarinic Acid as Bioactive Compound: Molecular and Physiological Aspects of Biosynthesis with Future Perspectives

The ester of caffeic acid with α-hydroxydihydrocaffeic acid, named rosmarinic acid (α-o-caffeoyl-3,4-dihydroxyphenyllactic acid; RA) can occur as oligomeric molecules, or in free, esterified, and glycosidic forms. Although it is commonly found among the members of the plants from the Lamiaceae (mints) and Boraginaceae (borages) families, only certain plant species produce a comparatively high concentration of RA. This valuable bioactive compound exhibits anti-cancer, anti-angiogenic, antioxidant, anti-inflammatory, antiviral, and antimicrobial properties, among others. As it is difficult to obtain high quantities of RA from natural sources, and since chemical manufacturing is costly and challenging, various biotechnological methods have recently been investigated to boost RA production. Plant cell tissue culture has been used to promote RA production in various plant species, particularly medicinal ones, with elicitation being the most commonly used technique. This review explores the main steps involved in RA biosynthesis in plants, including the molecular mechanisms and physiological alterations underlying its function, along with the primary mechanisms of RA accumulation in response to elicitation. Recent progress in synthetic biology-based RA synthesis, as well as metabolic engineering techniques to enhance the industrial production of this valuable bioactive constituent, are also discussed.