Antibacterial activity of saponin and alkaloidal extracts of whole plant of Phyllanthus niruri L., (Syn. P. franternus Webster)

Abstract

Saponins identified as phylagenin-13-O-α-D-glucopyranoside and phylangenin-25-O-β-D-glucopyranoside and alkaloid, extracted from the whole plant of Phyllanthus niruri, were tested for minimum inhibitory concentration (MICs) against Staphylococus aureus, Staphylococus pyrogenes, Escherichia coli, Salmonella typhi and Klebsiella pneumoniae. MIC of saponin against S. aureus SSH22 and SSH23 ranged from 5-15 μg/mL, and against E. coli OAUTH71 and K. pneumoniae OAUTH 54, from 15-60 μg/mL. MICs increased with the increase in concentration of cells used in the inoculum. S. aureus SSH22 exhibited a paradoxical biphasic response to saponin in nutrient broth, whereas bacterial activity against E. coli SSH31 increased with concentration up to the highest concentration of saponin tested. Activity against E. coli OAUTH71 was more pronounced in the phosphate-buffered saline than in the nutrient broth. The other active compound extracted (alkaloid) gave MIC values between 200 and 600 μg/mL.