Evaluation of combinatory effects of Anadenanthera colubrina, Libidibia ferrea and Pityrocarpa moniliformis fruits extracts and erythromycin against Staphylococcus aureus

Abstract

Anadenanthera colubrina, Libidibia ferrea and Pityrocarpa moniliformis are widely used in Caatinga and our group has demonstrated their biotechnology potential. This work evaluated the combined action of erythromycin with extracts obtained from fruits of A. colubrina(ACHE), L. ferrea (LFHE) and P. moniliformis (PMHE) against Staphylococcus aureus. The combinatory effects of hydroalcoholic fruit extracts were determined by the checkerboard method. The effects on bacterial DNA, membrane, protein and the major phenolic compounds were analyzed. PMHE demonstrated synergistic effects in six ratios (ΣFIC: 0.20 to 0.46), ACHE in five (ΣFIC: 0.18 to 0.33) and LFHE in four (ΣFIC: 0.20 to 0.47). An antagonistic effect was not found. The release of intracellular material was enhanced by about 30% in PMHE-treated cells, suggesting a contribution of membrane damage in its synergistic activity. DNA structural damage was observed when the bacteria were treated with LFHE and PMHE. The changes in protein release with all treatments suggest loss of cell viability and disturbances to metabolic pathways. Ultra fast liquid chromatographic (UFLC) analysis detected rutin (ACHE: 0.894 mg/g; PMHE: 0.177 mg/g), quercetin (ACHE: 0.353 mg/g; PMHE: 0.397 mg/g), gallic acid (LFHE: 0.855 mg/g) and a gallic acid derivative compound (LFHE: 0.866 mg/g). The extracts have great synergistic potential when combined with erythromycin, representing an alternative and sustainable use of natural resources from the Caatinga biome. Key words: Antimicrobials, Caatinga biome, checkerboard method, ultra fast liquid chromatographic (UFLC) analysis.