Antibacterial and antifungal potential of some polar solvent extracts of Ashwagandha (Solanaceae) against the nosocomial pathogens

Abstract

The aim of the present study is to evaluate the antimicrobial (antibacterial and antifungal) effects of hexane, toluene, isopropyl alcohol, acetone and ethanolic extracts of different parts (root and stem) of Withania somnifera (RUBL-20668) in order to use it as a possible source for new antimicrobial substances against important human pathogens. The dried and powdered parts were successively extracted using Soxhlet assembly; then antibacterial and antifungal activities were investigated by both, disc diffusion and serial dilution methods. The extract of W. somnifera significantly inhibited some important bacteria (two Gram +ve and four Gram-ve bacteria): Staphylococcus aureus (Gram +ve), Bacillus subtilis (Gram +ve), Escherichia coli (Gram-ve), Raoultella planticola (Gram -ve), Pseudomonas aeruginosa (Gram-ve), Enterobactor aerogens (Gram-ve), one yeast Candida albicans and one fungi Aspergillus flavus, to varying degrees. Isopropyl alcohol, acetone and toluene extracts of W. somnifera showed highest activity against the pathogens. The inhibitory effect is very identical in magnitude and comparable with that of standard antibiotics. Gentamycin, the standard antibacterial drug used, was effective in inhibiting these bacteria. The effect on E. coli, R. planticola and S. aureus were comparable to that of gentamycin. Ketoconazole, the standard antifungal used, was effective against the fungi. The inhibitory effect is very identical in magnitude and comparable with that of standard antibiotics used. Key words: Antibacterial, antifungal, solanaceae