ABSTRACT
We found that ethyl gallate purified from a dried pod of tara (
Caesalpinia spinosa
) intensified β-lactam susceptibility in methicillin-resistant and methicillin-sensitive strains of
Staphylococcus aureus
(MRSA and MSSA strains, respectively). This compound and several known alkyl gallates were tested with MRSA and MSSA strains to gain new insights into their structural functions in relation to antimicrobial and β-lactam susceptibility-intensifying activities. The maximum activity of alkyl gallates against MRSA and MSSA strains occurred at 1-nonyl and 1-decyl gallate, with an MIC at which 90% of the isolates tested were inhibited of 15.6 μg/ml. At concentrations lower than the MIC, alkyl gallates synergistically elevated the susceptibility of MRSA and MSSA strains to β-lactam antibiotics. Such a synergistic activity of the alkyl gallates appears to be specific for β-lactam antibiotics, because no significant changes were observed in the MICs of other classes of antibiotics examined in this study. The length of the alkyl chain was also associated with the modifying activity of the alkyl gallates, and the optimum length was C5 to C6. The present work clearly demonstrates that the length of the alkyl chain has a key role in the elevation of susceptibility to β-lactam antibiotics.
摘要
我们发现,从干豆荚中提纯的没食子酸乙酯(Tara (
spinosa
)可增强耐甲氧西林和甲氧西林敏感菌株对β-内酰胺类药物的敏感性。
金黄色葡萄球菌
(分别为 MRSA 和 MSSA 菌株)对β-内酰胺类药物的敏感性。我们用 MRSA 和 MSSA 菌株对该化合物和几种已知的烷基没食子酸盐进行了测试,以深入了解它们与抗菌和β-内酰胺类药物敏感性增强活性有关的结构功能。烷基没食子酸酯对 MRSA 和 MSSA 菌株的最大活性出现在 1-壬基和 1-癸基没食子酸酯上,90% 的受试分离菌被抑制的 MIC 值为 15.6 μg/ml。在低于 MIC 的浓度下,烷基没食子酸盐可协同提高 MRSA 和 MSSA 菌株对β-内酰胺类抗生素的敏感性。烷基没食子酸盐的这种协同活性似乎是针对β-内酰胺类抗生素的,因为在本研究中观察到的其他类抗生素的 MICs 没有明显变化。烷基链的长度也与烷基没食子酸盐的修饰活性有关,最佳长度为 C5 至 C6。本研究清楚地表明,烷基链的长度在提高对β-内酰胺类抗生素的敏感性方面起着关键作用。