Phytochemical analysis of Withania somnifera leaf extracts by GC-MS and evaluating antioxidants and antibacterial activities

Abstract

Many people in developing countries mainly depend on medicinal plants like Withania somnifera and their products for healthcare. In this study, reflux and maceration extraction methods were applied to investigate total phenolic (TPC) and flavonoid contents (TFC); and antioxidant properties of Withania somnifera extracts toward DPPH and hydrogen peroxide (H2O2) were studied. Highest TPC was detected with methanol extracts with value of 198.24 ± 1.16 mg GAE/g and TFC of 31.52 ± 0.91 mg QE/g. The minimum amount of TPC was observed in aqueous extract (101.41 ± 1.07 mg GAE/g) and the TFC in ethyl acetate extract 9.72 ± 1.32 mg QE/g. The maximum value of DPPH radical scavenging was estimated in maceration methanol extract 81.98 ± 0.49% and value of H2O2 was obtained in maceration acetone extract 76.18 ± 1.06%. The major identified molecules were Heptasiloxane,1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecamethyl-(50.04%), and trans-2,4 Dimethylthiane, S, S- dioxide (4.09%) The broad spectrum of antibacterial activity was observed in Escherichia coli reflux methanol extract. In both extraction techniques methanol was the best extracting solvent for phenolic and flavonoid contents as antioxidants as well as antibacterial activities.