Estudo farmacognÃstico e determinaÃÃo da atividade biolÃgica de Caesalpinia pyramidalis Tull. e Schinopsis brasiliensis Engl. frente a cepas de Staphylococcus aureus MRSA multirresistentes

Antonio Marcos Saraiva

The increase of bacterial resistance to antibiotics is a threat to the health of the global population, expanding the recurrence of infectious diseases due to the emergence of multiresistant bacteria, which makes the antimicrobial treatment difficult and costly. An important example of these germs is the MRSA Staphylococcus aureus which in Brazil, and also in other parts of the world, are the microorganisms frequently isolated, in the majority of cases at hospital level, being also an important cause of infections in communities. The occurrence of multiresistant MRSA S. aureus susceptible only to vancomycin represent a serious problem to be resolved, moreover since the appearance of recent strains of S. aureus with intermediate susceptibility and resistant to vancomycin. This fact is of fundamental importance for the study of alternative compositions, particularly on the base of medicinal plants which represent an unexhausted source of new molecules. In the present work, two plants have been chosen to study their phytochemical and antimicrobial action of medical plants: Schinopsis brasiliensis Engl. (BaraÃna or BraÃna), Anacardiaceae, both families with representatives of well known biological activity, including an antimicrobial one. In this sense has been studied the activity of dry extracts (by hexanolic extraction, in ethyl acetate extraction and methanol extraction) of the leaf, the bark of the Stem, the bark of Roots, the flower, the bean (fruit) and seed of BraÃna and Catingueira. Initially, in accordance with ATCC standards of negative Gram and positive Gram bacteria in which a better action against S. aureus was confirmed. In the second phase the tests were performed with 22 strains of S. aureus,18 multiresistant MRSA clinic isolates identified as Epidemic Clones, 2 MSSA S. aureus isolates and 2 ATCC strains. The results obtained from the plants in study, S. brasiliensis presented better activity against the strains of MRSA S. aureus including the more resistant epidemic clones. The dry metanolic extracts were more active with CMI data for the flower and root of BraÃna of 125 μg.mL-1 inasmuch as inhibition zones in the order of 20 mm obtained by the techniques of wells were found regarding one of the strains of multiresistant Methicillin-Resistant S. aureus (BEC). The dry extracts obtained by ethyl acetate demonstrate less action, which can be attributed to a diminished diffusion in the agar. In the tests, the antibiotics used as a standard were tetracycline and oxacilin in the determination of MIC and tetracycline in the techniques of wells, which confirmed attribution to oxacilin the MRSA or MSSA character regarding the strains and to tetracycline its resistant profile. The two dilutants used, DMSO of 50% and Tween 80 to 40%, did not present any inhibition. As a conclusion, it may be considered that the plants under study and particularly S. brasiliensis presented a promising activity towards the MRSA S. aureus strains including the multiresistant clones. It has been considered that in part this action is justified by the presence of the flavonoids and especially phenolics acids which were experimentally detected by bioautography which confirmed data of literature and by phytochemical screening

Estudo farmacognÃstico e determinaÃÃo da atividade biolÃgica de Caesalpinia pyramidalis Tull. e Schinopsis brasiliensis Engl. frente a cepas de Staphylococcus aureus MRSA multirresistentes

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