Extraction, quantitative determination and spectral identification of Carnosic Acid – a diterpene antioxidant from Rosmarinus officinalis

Carnosic acid is a benzenediol abietane diterpene having antioxidant and other medicinal activities. The medicinally active compound carnosic acid was isolated from leaves of the herb Rosmarinus officinalis. A simple solid-liquid extraction with solvent acetone in Soxhlet extractor was used for the extraction of compound from the plant source. The purity of the compound was studied using thin layer chromatography (TLC) and liquid chromatography-mass spectroscopy (LCMS) studies and the results were compared with standard carnosic acid. The result proves that the isolated compound was found to have 98.10% purity and no other impurities were observed. The molecular structure of the isolated compound was derived using spectral studies like UV, IR, NMR, C13 and mass spectroscopy. The spectral study proves that the compound has a molecular structure of 332 g/mol and molecular formula of C20H28O4.The molecular mass, formula and the molecular structure of the isolated compound was found to be similar to that of standard carnosic acid.