Abstract

ZAMPINI, Iris Catiana; CUDMANI, Norma  and  ISLA, María Inés. Antimicrobial activity of Argentine medicinal plants on antibiotic-resistant bacteria. Acta bioquím. clín. latinoam. [online]. 2007, vol.41, n.3, pp.385-393. ISSN 0325-2957.

The present study was conducted to investigate antimicrobial activity of alcoholic extracts of Argentine medicinal plant species (Dasyphyllum diacanthoides, Erythrina cristagalli, Larrea cuneifolia, Larrea divaricata, Phytolacca dioica, Pithecoctenium cynanchoides, Prosopanche americana, Schinus molle, Schkuhria pinnata, Senna aphylla and Solidago chilensis) against multidrug resistant human pathogen gram negative bacteria isolated from a Hospital in Tucumán, Argentina. Inhibition of bacterial growth was investigated using disc diffusion, agar macrodilution and broth microdilution methods against multiresistant clinical isolates of nine different specie of gram negative bacteria: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens, Morganella morganii, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia. A significant antimicrobial activity was found in three of the eleven plant species studied. Based on minimal inhibitory concentration (MIC) values, three plant species, L. divaricata, L. cuneifolia, and S. aphylla were the most potent ones with MIC values between 25-200 µg/mL. Overall, P. mirabilis, M. morganii and P. aeruginosa isolates were the most susceptible to these extracts with MIC values of 25 to 50 µg/mL. All extracts showed significant inhibitory activities on bacteria growth in a dose phenolic compound-dependent fashion. The minimal bactericidal concentration (MBC) values were identical to the MIC values or twofold higher than the corresponding MIC. Contact bioautography indicated that crude extracts possess several major antibacterial components. Phytochemical screening showed that the bioactive compounds correspond to polyphenols. Investigations are in progress to purify the bioactive principles.

Keywords : Argentine medicinal plants; antimicrobial activity; antibiotic-multiresistant gram negative bacteria; phenolic compounds.

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