Chemical Examination and Evaluation of Antioxidant and Antimicrobial Activities of Essential Oil from Gymnema sylvestre R. Br. Leaves

Abstract

The present study reports chemical examination and in vitro antioxidant and antimicrobial activities of essential oil isolated from leaves of a well known antidiabetic plant, Gymnema sylvestre R. Br. Essential oil was isolated from leaves by hydrodistillation using a Clevenger apparatus. The essential oil was found to contain 40 volatile compounds by GC/MS analysis. Hitherto unknown major components of essential oil identified by GC/MS analysis were found to be palmitic acid (17.8%), hydroquinone (13.9%), phytol (6.9%), pentadecanoic acid (6.8%), 4-vinyl guaiacol (4.5%), and eugenol (4.0%). Essential oil exhibited strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (IC50 28 μg/mL). Dose dependent antioxidant activity was shown by essential oil in β-carotene bleaching and 2,2-azinobis-(3-ethyl benzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical scavenging assays. The total phenolic content of essential oil was found to be 34 mg GAE/g fresh leaves. The essential oil inhibited the growth of Pseudomonas aeruginosa, Pseudomonas asplenii, Bacillus subtilis, Proteus mirabilis, Escherichia coli and fungus Candida albicans with minimal inhibitory concentration (MIC) varying between 22 mg/mL and 28 mg/mL