Azorella trifurcata and Mulinum echegarayii obtained from central region of<br>Argentina: antibacterial activity of their organic extracts

The natural products derived from medicinal plants have proven to be an abundant source of compounds with antibacterial activity. The antibacterial activity of extracts of Azorella trifurcata and M. echegarayii was evaluated against strains of Staphylococcus aureus ATCC 43300, Pseudomonas aeruginosa ATCC 27853, Listeria monocytogenes CLIP 74902 and Escherichia coli ATCC 35218. Organic extracts were prepared using n-hexane, mixtures of n-hexane and ethyl acetate of increasing polarity and a mixture of ethyl acetate and methanol on flash chromatography. All the extracts of A. trifurcata showed antibacterial effects against gram-positive bacteria (CIM between 0.5 and 2 mg/ml). Four extracts (100% n-hexane, 40:60/50:50 acetate: n-hexane, 70:30 ethyl acetate: n-hexane and 2:98 methanol: ethyl acetate) of A. trifurcata showed antibacterial activity against gram- negative bacteria. M. echegarayii 2:98 methanol: ethyl acetate was active against all gram-negative and gram-positive bacteria (CIM between 1 and 2 mg/ml). The values of MBC of the extracts assayed were one or two times higher than corresponding MIC values. The discovery of organics extracts with antibacterial properties could contribute to the treatment of bacterial infections.