Extraction, Isolation and Characterization of Rosmarinic Acid, a Major Polyphenol in Non-volatile Constituent of Mint Leaves

Mint (Mentha arvensis) is one of the most extensively cultivated aromatic plants worldwide for its essential oils. The non-volatile part of the plant serves as a rich source of medicinal agents. The present study was aimed to characterise the phytocomponents responsible for its wide spectrum of biological properties. The mint leaves were shadow dried, powdered and subjected to soxhlet extraction. The extract obtained was successively fractionated by column chromatography and the fractions were purified by preparative HPLC. The major component characterised by UV, IR, two dimensional 1H and 13C-NMR and Mass spectroscopy studies was found to be Rosmarinic acid (o-O-caffeoyl-3,4-dihydroxyphenyl-lactic acid). The presence of Rosmarinic acid in mint may be responsible for the various pharmacological properties.