从长隔木中提取的抗耐甲氧西林金黄色葡萄球菌（MRSA）化合物及其抗菌活性机制。
Anti-methicillin-resistance Staphylococcus aureus (MRSA) compounds from Bauhinia kockiana Korth. And their mechanism of antibacterial activity.
机构信息
Faculty of Pharmaceutical Sciences, UCSI University, No. 1 Jalan Menara Gading, UCSI Heights, 56000, Kuala Lumpur, Malaysia.
School of Science, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor Darul Ehsan, Malaysia.
出版信息
BMC Complement Altern Med. 2018 Feb 20;18(1):70. doi: 10.1186/s12906-018-2137-5.
BACKGROUND
Bauhinia kockiana originates from Peninsular Malaysia and it is grown as a garden ornamental plant. Our previous study reported that this plant exhibited fairly strong antioxidant and antimicrobial activities. This paper focused on the assessment of the antibacterial activity of B. kockiana towards methicillin-resistance Staphylococcus aureus (MRSA), to purify and to identify the antibacterial compounds, and to determine the mechanism of antibacterial activity.
METHODS
Antibacterial activity of B. kockiana flower was evaluated qualitatively and quantitatively using disc diffusion assay and microbroth dilution method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of extracts were examined. Phytochemical analysis was performed to determine the classes of phytochemicals in the extracts. Bioactivity guided isolation was employed to purify the antibacterial agents and identified via various spectroscopy methods. Scanning electron microscopy (SEM) technique was used to evaluate the antibacterial mechanism of extract and compounds isolated.
RESULTS
B. kockiana flower was found to exhibit fairly strong antibacterial activity towards both strains of MRSA bacteria used, MIC varies from 62.5-250 μg/mL. Tannins and flavonoids have been detected in the phytochemical analysis. Gallic acid and its ester derivatives purified from ethyl acetate extract could inhibit MRSA at 250-500 μg/mL. SEM revealed that the cells have undergone plasmolysis upon treatment with the extract and compounds.
CONCLUSION
Tannins and polyphenols are the antibacterial components towards MRSA in B. kockiana. Massive leakage of the cell content observed in treated cells showed that the phytochemicals have changed the properties of the cell membranes. Amphiphilic nature of the compounds exhibited the antibacterial activity towards MRSA via three stages: (1) cell membrane attachment; (2) cell membrane fluidity modification; and (3) cell membrane structure disruption.
背景
羊蹄甲原产于马来半岛，是一种园林观赏植物。我们之前的研究表明，该植物具有较强的抗氧化和抗菌活性。本文主要研究羊蹄甲花的抗菌活性，评估其对耐甲氧西林金黄色葡萄球菌（MRSA）的抑制作用，分离鉴定其抗菌活性成分，并探讨其抗菌机制。
方法
采用纸片扩散法和微量稀释法定性和定量评估羊蹄甲花的抗菌活性。检测提取物的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。采用植物化学分析方法确定提取物中植物化学物质的类别。采用生物活性导向分离法分离纯化抗菌剂，并通过各种光谱方法进行鉴定。扫描电子显微镜（SEM）技术用于评估提取物和分离得到的化合物的抗菌机制。
结果
羊蹄甲花对两种MRSA 菌株均表现出较强的抗菌活性，MIC 值在 62.5-250μg/ml 之间。植物化学分析检测到单宁和类黄酮。从乙酸乙酯提取物中分离得到的没食子酸及其酯衍生物在 250-500μg/ml 时可抑制 MRSA。SEM 显示，细胞在处理后发生质壁分离。
结论
单宁和多酚类化合物是羊蹄甲中抗 MRSA 的活性成分。处理后的细胞中观察到大量细胞内容物渗漏，表明植物化学物质改变了细胞膜的性质。化合物的两亲性通过三个阶段表现出对 MRSA 的抗菌活性：（1）细胞膜附着；（2）细胞膜流动性修饰；（3）细胞膜结构破坏。
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