Antibacterial activity of compounds isolated of a medicinal extracts from Caesalpinia paraguariensis

SGARIGLIA, M.A.; SOBERÓN, J.R.; SAMPIETRO D.A.; VATTUONE, M.A.

Tucumán

Congreso; VII Congreso Argentino de Microbiología General; 2011

Sociedad Argentina de Microbiología General

Resistance to antimicrobial agents has become an increasingly important and pressing global problem. Substantial investment and research in the field of antiinfectives are now desperately needed if a public health crisis is to be averted . Phytochemical research based on ethnopharmacological data is an effect ive approach in the discovery of new bioactive molecules. Moreover, the bioguided purification and analysis of plant medicinal extracts is a good method for isolating bioactive molecules. Infusion prepared from stem bark of C. paraguariensis (D. Parodi) Burk. (CPBI), is traditionally used because of their vulnerary properties; these properties suggested possible antimicrobial activity. We investigated the antibacterial activity of a medicinal extract and compounds isolated from this by bioguided purification. Collection microorganisms were used: S. aureus (ATCC25923) and E. coli (ATCC 25922 ). The microbial susceptibility tests were microdilution in liquid culture medium, and sub-cultured in solid medium, in order to obtain minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). respectively (according to CLSI, 2007). During biogu ided purification bioautographic technique was useful. Amoxicillin and Ciprofloxacin were used as positive controls. Lyophilized infusion was fractioned by sequential extraction with organic solvents. Methanolic fraction (MF, bioactive) was fractioned by Sephadex LH-20 column chromatography, and XII fractions were pooled. Five different compounds were isolated from III and XI f ractions (ABF, bioact ive) by RP-HPLC.They were identified by spectrometric techniques (MS(ESII Q-TOF). UV-VIS, H'-NMR, C13-NMR, etc.). According to the values of MIQMBC obtained, expressed as I..I g/ml, CPBI as well as their purified f ractions were act ive against the tested bacterial strains (CPSI: 200-3.000/800 - > 3.000 ; MF: 75100/ > 3.000 ; ABF: 50-75/> 3.000) and bioactive concentration values were lowering through purification. The isolated compounds were: gallic acid (A). ellagic acid (B), 3-0 -methyl ellagic acid (C). 3,3'-O-dimethyl ellagic acid (D) and 3,3'-O-dimethyl ellagic-4-b-D-xylopyranoside (E). These were tested up to 128 µg/ml, in accordance with CLSI for pure substances. B compound was active against both bacterial strains (MIC/CBM: 8-16/8 -16 µg/ml). C and D showed activity at higher concentration (32/64 and 64/128, respectively), A was active only against S. aureus, and E showed not activity at the assayed concentrations. The MIC/CBM values show that isolated compounds are promising antimicrobial agents, and we raise the possibility of carry out chemical change in bioactive molecules and to assay synergisms , in order to low those values. Our research results validated the medicinal property of this plant.