INHIBITORY ACTIVITY OF NATIVE AND NATURALIZED PLANTS FROM CENTRAL ARGENTINA AGAINST PSEUDOMONAS AERUGINOSA.

JORAY, M.B.; PALACIOS, S. M.; CARPINELLA, M.C.

Carlos Paz

Congreso; II Argentine Workshop in Current Topics in Pseudomonas and Burkholderia Research; 2009

Nowadays bacterial infections are increasing for different reasons mainly due to the development of resistance mechanisms to commercial antibiotics. This fact leaded to a certain reduction of their effectiveness. In this context, Pseudomonas aeruginosa has become increasingly recognized as an emerging opportunistic pathogen of clinical relevance. This situation represents a new challenge for the scientific community where has emerged a renewed interest in the development of new antibacterial agents.   Many of the currently available drugs have been first isolated from natural sources and in this sense, plants represent a promising source of them. Plants produce a great number of secondary metabolites with different activities such as defense against microbial attack. Therefore, the isolation of active compounds from plant extracts represents new possibilities for finding novel antibacterial molecules. Ethanolic extracts from 51 native and naturalized plants from central region of Argentina were studied for their inhibitory effect against Pseudomonas aeruginosa (ATCC 27853). According to MIC and MBC values, the most potent extracts in descendent order were those obtained from Achyrocline satureioides, Flourensia oolepis, Lepechinia floribunda and Lithrea molleoides. In order to isolate the compounds responsible for their antibacterial activity, A. satureioides and L. molleoides were submitted to bioguided isolation. Through different chromatographic techniques, both vegetal extracts were fractionated yielding one active molecule from each plant. From A. satureioides a compound identified as 23-methyl-6-O-desmethylauricepyrone (1) was isolated. Compound 1 showed a high effectiveness against P. aeruginosa with MIC and MBC values of 0.625 mg/mL. From L. molleoides one compound belonging to alkylresorcinols was obtained. It was identified as (Z,Z)-5-(trideca-4, 7-dienyl)-resorcinol (2). This compound showed MIC and MBC values of 4 mg/mL. As observed, these values were higher than those obtained for compound 1, however, these findings are very interesting if we consider that few compounds exhibit inhibitory activity against Gram-negative bacteria. These results open the possibility of using the mentioned plant extracts and the isolated compounds as therapeutic agents for treating bacterial infections or as leading molecules for synthesis of new antibiotics.