Monitoring in vitro efficacy of Holarrhena antidysenterica against multidrug resistant enteropathogenic bacteria

Abstract

ObjectiveTo assess antibacterial activities of leaf and bark extracts of Holarrhena antidysenterica (H. antidysenterica), used by an Indian aborigine for ailments of human gastrointestinal tract, against eight extended spectrum β-lactamase producing multidrug resistant enteropathogens. MethodsAntibacterial activities of eight solvent-extracts of the plant were monitored by the agar-well diffusion method on lawns of all bacteria. Further, minimum inhibitory concentrations and minimum bactericidal concentrations of the best three solvent extracts were determined by the micro-broth dilution method. Preliminary phytochemical analysis of the active leaf and bark extracts were carried out. ResultsIt was found that Enterobacter aerogenes was resistant to 14 of 16 antibiotics, likewise, Escherichia coli to 13, Klebsiella sp. to 14, Salmonella paratyphi to 7, Salmonella typhi to 15, Shigella dysenteriae and Shigella sonnei to 14, Vibrio cholerae to 4 of 16 antibiotics. It was found that plant-extracts with petroleum ether and n-hexane had the least antibacterial activity. Extracts of leaves with chloroform, methanol, and water registered moderate antibacterial activity, whereas bark-extracts with ethyl acetate, acetone, and ethanol had a comparatively higher antibacterial activity on all these strains. Maximum sizes of zone of inhibition due to leaf extracts with ethyl acetate, acetone, and ethanol, and on the other hand, bark extracts with ethyl acetate, acetone and methanol were recorded against these bacteria; minimum inhibitory concentration and minimum bactericidal concentration values of specifically these extracts were determined. Phytochemical analysis of the methanolic bark extract of H. antidysenterica confirmed the presence of alkaloids, terpenoids, reducing sugars, tannins, and flavonoids. ConclusionData analysis revealed that leaves and bark of H. antidysenterica could serve as complementary/supplementary drugs along with suitable antibiotics to control the marauding multidrug resistant enteropathogens.