Antioxidant and Antimicrobial Properties of Ocimum sanctum and Cymbopogon nardus

Abstract

Plant extracts have gained popularity recently, for their importance as potential antioxidative and antimicrobial agents. These properties have been attributed to their phytochemical content. The extraction solvent and the plant part are among the factors that influence the yield of these phytochemicals This study was therefore undertaken to investigate the antimicrobial and antioxidant activities of extracts of the leaf and stem of Ocimum sanctum (holy basil) and Cymbopogon nardus (citronella grass); two commonly occurring plants in South East Asia. The extracts were obtained by solvent extraction using water, methanol and ethanol. The percentage yield, antimicrobial activity, antioxidant activity and high-performance liquid chromatography (HPLC) analysis was investigated. The organic extracts yielded a higher percentage recovery of phytochemicals compared to the water extracts.  HPLC analysis revealed the presence of chlorogenic acid in all extracts; rutin only in the leaf extracts and the citronella grass leaf extract contained both rutin and gallic acid. Antimicrobial assays were performed using the agar well diffusion method with tetracycline as positive control. Basil extracts exerted a greater inhibitory growth on both S. aureus and E. coli. S. aureus was found to be more susceptible to the presence of plant extracts. Water extracts did not display any zones of inhibition. The DPPH (2,2-diphenyl-1-picrylhydrazyl) assay was used to study the antioxidant effect with Vitamin C (0.1mg/ml) as positive control. The results indicated that the Basil leaf extracts possessed greater antioxidant potential compared to the stem. The study concludes that organic extracts of O. sanctum and C. nardus possess pharmaceutical properties.