Avaliação in vitro da atividade antimicrobiana e citotoxicidade de substâncias naturais frente a microrganismos causadores de mastite bovina

Abstract

The use of medicinal plants in the treatment of many diseases is associated with the popular medicine from different parts of the world. Each day, the microrganisms that cause damages to the human and animal health have shown more resistance to most of the known antibiotics, stimulating the search for new antimicrobials substances, mainly from natural occurrence. The use of the specie Pterodon ermaginatus and genus Lippia as anti-inflammatory, antirheumatic and analgesic drugs in the popular medicine is widely spread. For the evaluation of the antimicrobial activity the species Pterodon emarginatus Vog., Lippia lacunosa, Lippia rotundifolia and Lippia salvifolia were selected the microrganisms (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Streptococcus bovis and Klebsiella pneumoniae) which were retrieved from animals with mastitis raised on farms in the country side of Minas Gerais. From P. ermaginatus were tested the hexanic (HF), ethyl acetate (AEF), buthanol (BF), methanol (MF) and ethanol (EF) fractions. The antimicrobial activity was evidenced by the HF and EF. The smallest MIC found was of the HF against S. dysgalactiae in the concentration of 0.625 mg/mL. For the attainment of peptides of Lippia, the aqueous extracts (AE) from its leaves and flowers had been prepared. The AE of L. salvifolia and L. lacunosa were bacteriostatic (MIC=80 µ g/mL) for S. aureus and S. agalactiae, respectively. L. rotundifolia was bacteriostatic against S. uberis (MIC=10 µ g/mL). The test of cellular viability for the extracts of Lippia sp showed that they were not toxic when compared to the control. The morphologic analysis showed that alterations in the format of the cells occurred in a concentration ≥ 80 µ g/mL. These results of this study provide additional evidence that these plants have antimicrobial potential against microrganisms that cause bovine mastitis and suggest its use as a natural antiseptic.