Antibacterial activity of the ethyl acetate part of Abrus cantoniensis against Staphylococcus aureus

Abstract

Abstract Objective: The aim of this work was to measure the antibacterial activity (against Escherichia coli and Staphylococcus aureus [S. aureus]) of the ethyl acetate part of Abrus cantoniensis and assess their potential as medicines. Methods: The experiment was divided into four groups: negative control group [with Mueller-Hinton broth (MHB)], positive control group (with 75% ethanol), blank group (with MHB) and test group (with the ethyl acetate part of Abrus cantoniensis). The antibacterial activities of the extracts were evaluated by the Oxford cup assay and minimum inhibitory concentration (MIC). Time-kill curve experiments, scanning electron microscopy, the content of DNA, RNA and protein were used to study the antibacterial mechanism of the ethyl acetate extract part on the growth and viability of S. aureus. The study procedures were approved by the Animal Care and Use Committee of Xi’an Jiaotong University (approval No. XJTULAC2016-412) on January 22, 2016. Results: The ethyl acetate part of Abrus cantoniensis extract exhibited the highest inhibitory activity against the growth of S. aureus with an inhibition zone diameter of 16.4 mm and MIC value of 0.5 μg/mL. The general activity range of the ethyl acetate part, determined using a time-killing curve, was found to be 0.5 μg/mL to 40 μg/mL (MIC to 80 × MIC). Changes in the scanning electron microscopy images and of DNA, RNA and proteins of S. aureus indicated possible mechanisms of the inhibitory activity of the ethyl acetate part. Conclusion: The ethyl acetate part of Abrus cantoniensis damaged bacterial cell structures, which results in protoplasm leakage, and eventually bacterial cell death.