Screening of Phyllanthus Species for Antimicrobial Properties

The development of resistant pathogenic microorganism against conventional antibiotic drugs has risen to a point of global concern. New antimicrobial compounds with diverse chemical structures and novel mechanisms of action are therefore needed to curb the new and re-emerging infectious diseases. This study has identified two Phyllanthus species (Phyllanthus amarus, Phyllanthus odontadenius) sampled from Nairobi and Siaya counties in Kenya. In vitro activity of extracts of these species and correlated their efficacy was compared with the commercial extracts of P. niruri that are in the Kenyan market. Disk diffusion method was employed to screen the antimicrobial activities of both the extracts and two standard antibiotics; 0.32mg mL-1 gentamycin and 0.30 mg mL-1 Nystatin. The dichloromethane(DCM):methanol (1:1) extracts of Phyllanthus odontodenius showed the strongest activity against all the organisms both at 100 mg μL and 50 mg μL-1 followed by both the hot water and cold water methanol extracts. The solvents in comparison to antibiotics showed 80% activity for methanol, 48% for DCM:MeOH 1:1, 43% in hot water and 28% for cold water. Thin layer chromatography (TLC) showed that the compounds found in the three species were identical. This study has shown that, the two species possess significant antimicrobial activity and justifies the use of their extracts by herbalists in the treatment of many microbial diseases. Therefore, further bioassay guided fractionation, isolation and characterization studies of compounds from these extracts are needed to confirm the active components and mechanisms of action of these two species.