In vitro Total Antioxidant and Radical Scavenging Activities of Organic Extracts from Leaves, Stem and Inflorescence of Cannabis sativa L.

Abstract

The in vitro total antioxidant and radical scavenging properties of organic extracts from leaves, stem and inflorescence of male and female plants of Cannabis sativa were studied using 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging, total phenolic conents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, lipid peroxidation inhibition and metal chelating activity assays. The stem, leaves and inflorescence of male (MS, ML and MI, respectively) and female (FS, FL and FI, respectively) plants were initially extracted in methanol and subsequently partitioned in n-hexane, chloroform, ethyl acetate and 1-butanol, successively. Employing ABTS radical scavenging activity assay the fractions obtained in polar solvents exhibited high ABTS scavenging activity. Trolox equivalent antioxidant capacity (TEAC) values obtained for various extracts of different parts of C. sativa ranged from 144.46-1.47 mM trolox equivalents for 1-butanol fraction of FI and chloroform fraction of FS, respectively. Total phenolic contents using Folin-Ciocalteu's method ranged from 3.562-0.339 mg/L gallic acid equivalent for 1-butanol fraction of FS and chloroform fraction of MI, respectively. A direct relationship between Trolox equivalent antioxidant capacity and total phenolic contents values was not observed for the extracts except for MS indicating that only phenolic compounds were not responsible for the total antioxidant activity of the fractions. The rate of scavenging of DPPH radical for these extracts reflected the presence of a diverse nature of antioxidative components. Using ammonium thiocyanate method, all the extracts of both the genders demonstrated significant lipid peroxidation inhibition activity. The per cent chelating activity using ferrozine as reference chelator ranged from 9.46-84.94 for ethyl acetate fraction of ML and methanol fraction of FL, respectively. A poor correlation of ferrous ion chelating activity with total phenolic conents of the extracts was observed and this indicates that phenolic compounds might not be the main chelators of iron ions.