Preliminary study on the antibacterial activity of some medicinal plants of Khuzestan(Iran)

Objective:To search for antimicrobial agents among natural products.Methods:Ethanolic extracts of 4 plant species,including Beta vulgaris L.(Chenopodiaceae),Amaranthus graecizans (A.graecizans) L.(Amaranthaceae),Rumex obtusifolius(R.obtusifolius) L.and Polygonum patulum(P.patulum) M.B.(Polygonaceae),were evaluated for antibacterial activity using agar disc diffusion method against some gram-positive and gram-negative bacteria[Pseudomonas aeruginosa(P.aeruginosa),Listeria monocytogenes(L.monocytogenes).Staphylococcus epidermidis(S.epidermidis),Staphylococcus aureus(S.aureus),Klebsiella pneumoniae(K. pneumoniae),Salmonella typhi(S.typhi),Bacillus cereus(B.cereus).Bacillus anthracis(B. anthracis),Escherichia coli(E.coli) and Streptococcus pyogenes(Str.pyogenes)].These extracts were obtained from aerial parts of the used plants.Results:The majority of these extracts had inhibitory effect at different concentrations(0.05 g/mL,0.10 g/mL,0.20 g/mL and 0.40 g/mL) against above mentioned bacteria.E.coli was the most resistant strain.The highest inhibitory zone was showed by ethanolic extract of P.patulum against Str.pyogenes(28 mm) and followed by ethanolic extract of B.vulgaris against S.epidermidis(23 mm).The extract of A.graecizans didn’t show inhibitory activity except at 0.40 g/mL against B.cereus.The minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) values of R.obtusifolius extract that was measured against Str.pyogenes were equal(MIC=MBC=5.00mg/mL).Conclusion: The findings of this study could also be as new source for antibiotics discovery and infection treatment.