Antioxidant and antibacterial activities of terminalia mantaly H. Perrier (Combretaceae) on multidrug resistant (MDR) wound pathogens

Abstract

Multidrug resistant (MDR) wound pathogens have rendered many antimicrobials ineffective in the treatment of infected wounds. Medicinal plants used to treat wound infections, especially in developing countries can furnish new and effective agents. Therefore, Terminalia mantaly used locally to treat infections was evaluated for antioxidant and antibacterial activities. Methanol extracts of leaves and roots were tested at 20 and 10mg/ml on thirty-two clinical isolates of wound bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus) from three Nigerian hospitals. Antibacterial activity and Minimum Inhibitory Concentration (MIC) were determined by agar well diffusion and agar dilution methods respectively. Antioxidant activities were evaluated by catalase, lipid peroxidation, hydrogen peroxide and DPPH free radical scavenging activities. The extracts showed good antibacterial activity with zones of inhibition between 12-35mm on all the tested pathogens with better activity on Gram–negative bacteria including the MDR strains. The MICs (and MBC) of leaf and root extracts were between 0.625-5mg/ml (1.25-10mg/ml) and 0.625-5mg/ml (1.25-5mg/ml) respectively. Leaf extract gave good antioxidant activity, better than root (comparable with ascorbic acid) of 73.77% inhibition on hydrogen peroxide scavenging, 76.36% inhibition on lipid peroxidation and 61.68% DPPH radical scavenging activities. Extracts of Terminalia mantaly showed good antioxidant and antibacterial activities, justifying the traditional uses of the plants. Further, the activity on MDR pathogens revealed the plant as a potential source of newer antibacterial agents for treating wound infections caused by MDR pathogens.