ORIGINAL ARTICLE The article was published by Academy of Chemistry of Globe Publications www.acgpubs.org/RNP © Published 06/ 07/2009 Rec. Nat. Prod. 3:3 (2009) 131-138 Investigation of Ethyl Acetate Extract/Fractions of Acacia nilotica willd. Ex Del as Potent Antioxidant Rajbir Singh 1 , Bikram Singh 2 , Sukhpreet Singh 3 , Neeraj Kumar 2 , Subodh Kumar 3 and Saroj Arora 1* 1 Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar-143 005, Punjab INDIA 2 Division of Natural Plant Products, Institute of Himalayan Bioresource Technology Palampur, H. P. -176 061 INDIA 3 Department of Chemistry, Guru Nanak Dev University, Amritsar-143 005, Punjab INDIA. . (Received November 11, 2008; Revised February 19, 2009; Accepted April 15, 2009 ) Abstract: This study was planned to evaluate the antioxidant activity of ethyl acetate extract/fractions of Acacia nilotica Willd. Ex. Del extracted with different solvents of increasing and decreasing order of solvent polarity. The antioxidative activities, including the 1’-1’ diphenylpicryl-hydrazyl (DPPH) radical-scavenging effects, hydroxyl radical scavenging potential, chelating ability, reducing power and lipid peroxidation inhibition in rat tissue homogenate were studied in vitro. It was found that the antioxidative effect provided by extract/fractions was strongly concentration dependent and increased on fractionating the extract into water and ethyl acetate fractions. In general, the antioxidative activity increased with increasing extract/fractions concentration to a certain extent, and then leveled off with further increase in antioxidant activity. From a comparison of the antioxidant potential and IC 50 values for different antioxidative reactions, it seemed that extract/fractions were more effective in scavenging DPPH and hydroxyl radicals than reducing, chelating heavy metals and lipid peroxidation inhibitory potential. Keywords: Acacia nilotica; free radicals; phytochemicals; antioxidant assays; DPPH; lipid peroxidation. * Corresponding author: E-Mail: sohirajbir@rediffmail.com