In vitro Evaluation of Antioxidant Potential of Isolated Compounds and Various Extracts of Peel of Punica granatum L.

BACKGROUND: Punica granatum L. (Lythraceae) peel has been proven to exhibit widespread pharmacological application against multitude of diseases due to the presence of bioactive principles. OBJECTIVE: The objective is to isolate the bioactive compounds from the pericarp of P. granatum and to evaluate the antioxidant activity of various extracts. MATERIALS AND METHODS: Dried peel of P. granatum was extracted with aqueous acetone and chromatographed on Diaion HP-20. Enriched fractions were rechromatographed on Sephadex LH-20 and purified on preparative high-performance liquid chromatography to identify individual compounds. The dried peel was extracted with different solvents to evaluate the antioxidant activity of the extracts. RESULTS: On the chemical investigation, three compounds were isolated and characterized as punicalagin, 2,3-(S)-hexahydroxydiphenoyl-D-glucose, and punicalin, using various spectroscopic techniques. CONCLUSION: Results indicate that the isolated compounds have possessed antioxidant activity, and aqueous, methanol, and aqueous acetone extract showed significant scavenging of 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radicals. SUMMARY: In vitro antioxidant activity of Punica granatum extracts was evaluated by 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) assay. Dried peel of P. granatum was extracted with different solvents to evaluate the antioxidant activity of the extracts. Aqueous acetone extract was found to be most active and chromatographed further to afford punicalagin, 2,3-(S)-hexahydroxydiphenoyl-D-glucose, and punicalin. The presence of antioxidant properties of three compounds in the peel of P. granatum has been demonstrated. [Image: see text] Abbreviations Used: HPLC: High-performance liquid chromatography; HHDP: Hexahydroxydiphenoyl; DPPH: 2,2-diphenyl-1-picrylhydrazyl; ABTS: 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid); UV: Ultraviolet; PDA: Photodiode array; LC: Liquid chromatography; NMR: Nuclear magnetic resonance; MHz: Megahertz; w/v: Weight by volume; MS: Mass spectra.