Abstract

COMPARATIVE IN VITRO ANTIOXIDANT ACTIVITY OF EXTRACTS OF AERIAL PARTS OF GINKGO BILOBA L. FROM KUMAUN HIMALAYA

Lalit M. Tewari, Brij M. Upreti, Geeta Tewari*, Manoj K. Singh and Tapan
Nailwal

Abstract

The present study was carried out to evaluate the antioxidant activity of leaf and twig methanol, hexane and DCM extracts of Ginkgo biloba L., a valuable rare exotic medicinal plant. This was achieved by radical scavenging, metal chelating, FRAP assay and ABTS radical scavenging activity determination. Total phenolic and flavonoid contents were also evaluated. Among the extractants, methanol gave the best results for phenolic content (285±0.12 mg gallic acid equivalent (GAE)/g dry weight)) and FRAP (224±0.20 mg gallic acid equivalent (GAE)/g dry weight) assay especially, in case of leaf extract. For flavonoids content, DCM extract (278.64±0.77 AAE /100 g dry weight) showed the best result with leaf extract. Total phenolic, flavonoid contents and FRAP activity were estimated in the highest amount from leaf extracts as compared of the twig extracts. For DPPH activity, hexane leaf extract and DCM twig extract showed maximum activity with, however, for ABTS activity, hexane leaf and hexane twig and for metal chelating, DCM leaf and methanol twig extracts showed maximum EC50 in comparison to the standards. FRAP and DPPH antioxidant activity showed significant positive relationships with total phenolic content while flavonoid was significantly correlated with FRAP antioxidant activity. Flavonoid content showed significant negative correlation with the antioxidant activity performed by metal chelating method.

Keywords: Antioxidant activity, total phenolic content, FRAP, flavenoids, Ginkgo biloba L.