Antimicrobial activity of five plants from Northern Mexico on medically important bacteria

Abstract

The aim of this study was to evaluate the potential antimicrobial activity of five medicinal plants from Northern Mexico against ATCC bacteria Klebsiella pneumoniae (9183),Staphylococcus aureus (BAA44), Escherichia coli (O157), Enterobacter aerogenes(9180) and Enterobacter cloacae (9235) and eight clinical isolated strains (CI) Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Sarcina lutea and Streptococcus pyogenes. Methanolic extracts of the leaves were tested against these bacterial strains using diffusion on agar method. The extracts showed antimicrobial activity against at least one of the microorganisms tested. Leucophyllum frutescens showed antimicrobial activity against Staphylococcus aureus (CI) and Escherichia coli O157 the minimal inhibitory concentration (MIC) was 28.0 and 30.0 mg/ml, respectively; Tecoma stans inhibited the growth of Staphylococcus aureus (CI) MIC 36.1 mg/ml; Fouquieria splendens showed antimicrobial activity against Staphylococcus aureus and E. coli O157 MIC 25.0 and 27.1mg/ml, respectively, Euphorbia antisyphylitica resulted active against E. aerogenes 9183 and S. aureus (CI) MIC 30.1 and 26.8 mg/ml respectively. Acacia farnesiana did not show any antimicrobial activity. With the bioassay of Artemia salina, only the extract of L. frutescens showed toxicity (DL50 de 196.7 mg/ml). The dichloromethane soluble fraction of methanolic extract of L. frutescens with bioautography assay revealed three bands in the TLC, showed a broad spectrum activity against S. aureus (IC). This findings could increase scientific knowledge of medicinal plants from North of Mexico with antibacterial properties.   Key words: Toxicity, antimicrobial activity, methanolic extracts, medicinal plants. bioautography.