ANTIMICROBIAL STUDIES ON ALTERNANTHERA SESSILIS Red LEAVES

Abstract

Plants have exceptional abilities to produce secondary metabolites that have medicinal value as well as being cytotoxic agents. With the rise of multidrug-resistant strains of bacteria like Vancomycin-resistant Staphylococcus aureus (VRSA) and Methicillin Resistant Staphylococcus aureus (MRSA) has required the discovery of new antimicrobial drug leads. Currently there is not a single chemical entity plant derived antibacterials being used clinically. Malaysia with its abundant biodiversity has many plants which are used in traditional medicine to treat wound infections and with knowledge gathered from ethnobotany lead to this study of the antimicrobial activity of Alternanthera sessilis Red (locally called Hongtyang wu) leaves ethanolic extract on 11 standard microorganisms namely Methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, Staphylococcus epidermis, Staphylococcus saprophyticus, Enterococcus fecalis, Bacillus cereus, Escherichia coli, Klebsiella pneumoniae, Acinetobacter iwoffii, Shigella dysenteriae, Aeromonas hydrophilia and Yersinia enterocolitica. In the present study, two microorganisms namely, the gram positive S. aureus and B. cereus exhibited susceptibility to the ethanolic leaves extract using the disk diffusion assay method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were performed using the Resazurin assay (broth microdilution techniques) as described by the Clinical and Laboratory Standards Institute (CLSI). The MIC values were 12.5mg/mL and 0.2mg/mL for B. cereus and S. aureus respectively and A. sessilis Red ethanolic leaves extract killed these 2 types of microorganisms at MBC values of 25mg/mL and 0.4 mg/mL, respectively. The results showed that A. sessilis Red ethanolic leaves extract either modified resistance in B. cereus and S. aureus and/or acted as antibacterial agent by possessing bactericidal or bacteriostatic properties. The leaf extract had potent activity against S. aureus which could be exploited to develop new classes of anti-staphylococcal phytochemical agents which should undergo further microbial specificity, cytotoxic and preclinical in vivo evaluation to determine their development for clinically use.