Assessment of antimicrobial activity of Saxifraga ligulata.

摘要

Benzene, petroleum-ether, chloroform and ethyl acetate extracts of Saxifraga ligulata were tested against three Gram positive bacteria viz., Bacillus subtilis, B. megaterium and Staphylococcus aureus, and five Gram negative bacteria viz., Escherichia coli, Salmonella typhimurium, Pseudomonas fluorescence, Ps. aeruginosa and Pantoea ananetis. The minimum inhibitory concentration (MIC) values of each fraction against all the bacteria were tested. Petroleum ether fraction was found most effective, followed by ethyl acetate fraction. Both the fractions were found effective to kill all the bacteria tested, but at different doses. Benzene fraction was effective at very low concentration but was unable to produce any effect on Gram positive Staphylococcus aureus and Gram negative Escherichia coli. Morphology of the bacteria was severely affected when they were treated with sub lethal concentration of solvent fractions as revealed by the study of scanning electron microscopy. Also, the petroleum ether extract showed very strong antifungal activity against three plant pathogenic fungal species which were Alternaria solani, Helminthosporium oryzae and Fusarium oxysporum at nearly 250 micro g/ml. This extract strongly interferes with oxido-reductase enzymes of the TCA cycle.