Antibacterial and Antioxidant Activities of 3-O-methyl Ellagic Acid 4'-rhamnoside from Stem Bark of Polyalthia longifolia Thw.

The plant Polyalthia longifolia (Annonaceae) is an ornamental tree that finds its reference in Indian medicinal literature owing to its popular Hindi name Ashoka i.e, Saraca indica. However, P. longifolia is equated with the name Asoka and often used as an adulterant or substitute of the genuine Asoka bark. The present investigation was carried out with an object to separate and isolate active phytomolecule(s) from stem bark of P. longifolia and to screen their antibacterial and antioxidant potential. Column chromatography of the butanol fraction of the hydroalcoholic extract (methanol:water, 1:1) has led to the isolation of a phenolic compound. Structural elucidation was done by IR, 1H NMR, 13C NMR, DEPT, COSY, HSQC, HMBC and mass spectroscopy techniques, and purity was checked by HPTLC and HPLC. Butanol fraction and the isolated compound were screened for antibacterial activity (against facultative aerobic and fastidious aerobic bacterial strains) and antioxidant potential (DPPH method). The compound was revealed to be 3-O-methyl ellagic acid 4'-rhamnoside (1), and the purity of the compound was 99.2%. The isolated compound comprises promising antibacterial and antioxidant activities.