Antibacterial and cytotoxic activities of Argentine medicinal plant extracts

ZAMPINI I. C; VATTUONE M. A; ISLA M. I

Nápoles- Italia

Simposio; 3° International Symposium on Natural Drugs.; 2003

Antíbacterial activity of alcoholic extracts of Argentine plant species against 51 clinical isolates of ten different species of Gram-negative bacteria was investigated. These isolates included cefotaxime-resistant and ceftazidime­- resistant bacteria. Imipenem had a good activity against the cefotaxime-resistant Enterobacteria tested. However meropenem had limited activity against the cefotaxime and ceftazídime-resistant bacteria. Based on minimal inhibitory concentration (MIC) values Eugenia uniflora and Larrea divaricata extracts were the most potent followed by Larrea cuneifolia, Zuccagnia punctata and Cassia aphylla ethanolic extracts (MIC values between 25- 200 µg/ml). P mirabilis, A. baumani and S. maltophilia isolates were the most susceptible to these extracts with MIC values of 25 µg/ml followed by M. morganii and P. aeruginosa (MIC values of 50 µg/ml). The most resístant strains were K.pneumoniae, E. coli, S. marscences with MIC values of 200 µg/ml. The bactericidal kinetic curve were made. A noticeable reduction of bacteria viability was observed after an incubation time of 2 to 4 h. This may indicate a bactericidal effect. Although the MIC obtained with the ethanolic extracts are higher than those of imipenem (0.25 to 16 µg/ml), these results are interesting since they have obtained with a crude extracts and not with a pure product. All ethanolic extracts showed significant lethality to brine shrimp assay (LC50 5 to 50 µg/ml). LC50 values are similar to that of cytotoxic compounds which not require metabolic activation (podophyllotoxin and berberine chloride). On the basis of this finding, these plant species will be subjected to further phytochemical analysis.