In vitro anti-bacterial activity of aqueous extracts of the whole plant, flowers, roots, leaves and stem of grass Heteropogon contortus grown in Sri Lanka

Abstract

In vitro antibacterial potential of aqueous extracts of Heteropogon contortus (whole plant, leaves, flowers, stem and roots) were examined against gram negative and positive pathogen; Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) respectively. Concentrations tested were 100 and 200 mg/mL, using agar well diffusion bioassay technique. Gentamicin (1µg/mL) was used as the positive control and distilled water as the negative control. The results revealed that different parts of the plant exhibit different degrees of antibacterial activity. The ranking of the potency of antibacterial activity against Escherichia coli was whole plant > leaves > flowers > root > stem, while whole plant > flowers > roots > leaves > stem for Staphylococcus aureus. Phytochemical analysis revealed the presence of alkaloids, flavonoids, diterpenes and glycosides in certain parts of the plant while phenols, proteins and amino acids were found in all parts. The antibacterial activity is likely to be mediated by synergistic action via multiple mechanisms. A strong possibility exists to develop a safe and potent antibacterial agent from Heteropogon contortus.