Antimicrobial effects of five Iranian popular medicinal plants on some intestinal bacteria

Gastrointestinal infections are still a major concern in the developing countries. The aim of this research was to investigate antimicrobial effects of five herbs in Iranian traditional medicine on some of the pathogenic intestinal bacteria. Hydroalcoholic extracts of Amaranthus paniculatus L. (seeds), Cannabis sativa L. (fruits), Rhus coriaria L. (epicarps), Urtica dioica L. (leaves), and Zataria multiflora Boiss. (aerial parts), obtained from Tehran botanicals market and identified by the Herbarium of School of Pharmacy, Tehran University of Medical Sciences, were prepared by cool percolation method using ethanol 80. Antimicrobial activities of the extracts against several standard bacteria including Escherichia coli ATCC 8739, Staphylococcus aureus 6539-p, Staphylococcus epidermidis ATCC 12229, Bacillus cereus PTCC 1274, and also clinical isolates of Salmonella typhi, Proteus vulgaris, Seratia marsesence and Shigella flexneri were carried out using disc and well diffusion methods. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the most two potent extracts were determined using microdilution method. Screening of the herbal extract for their possible antimicrobial effects using disc diffusion method revealed that at least two of the extracts R.coriaria L. and Z. multiflora Boiss. had considerable effects. The potential of antibacterial activities of the two extract were further evaluated using MIC and MBC methods. The MICs of R.coriaria L. on S. marsesence and B. cereus compared to GM were about 50 and on S. aureus, Pro. Vulgaris and E. coli were about 200. R.coriaria L. did not have bactericidal effect on B. cereus and E. coli. Rhus coriaria, an Iranian traditional herb with astringent effect and as a spice agent seems to have promising inhibitory effect on some bacteria involved in gastrointestinal infections.