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

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

San Miguel de Tucumán

Congreso; VII Congreso Argentino de Microbiologia General SAMIGE del Bicentenario,; 2011

SAMIGE

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 effective approach in the discovery of new bioactive molecules. Moreover, the bioguided purifi cation 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 beca use 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 (ATCC 25923) 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 minima l bactericidal concentration (MBC), respectively (according to CLSI , 2007). During bioguided 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 fractions (ABF, bioactive) by RP-HPLC.They were ident if ied by spectrometric t echniques (MS(ESI! Q-TOF), UV-VIS, H'-NMR, C" -NMR, etc.). According to the values of MIC/MBC obtained, expressed as IJg/m l, CPBI as well as their purified fractions were active against the tested bacterial strains (CPSI : 200-3 .000/800- > 3.000; MF: 75-100/> 3.000; ABF: 50-75/> 3.000), and bioactive concentration values were lowering through purification. The isolated compounds were: ga ll ic acid (A), ellagic acid (B), 3-0 -methyl ellagic acid (C), 3,3'-O-dimethyl ellagic acid (D) and 3,3'-O-dimethyl e llagic- 4-~ - D-xylopyranosid e (E). These were tested up to 128IJg/ml, in accordance with CLSI for pure substances. B compound was active against both bacterial stra ins (MIC/CBM: 8-16/8-1 6 IJg/ ml). C and D showed activity at higher concentration (32/64 and 64/128, respectively)' A was act ive 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 synerg isms, in order to low those values. Our research results val idated the medicinal property of this plant.