Unexplored antifungal activity of linear battacin lipopeptides against planktonic and mature biofilms of C-albicans
Unexplored antifungal activity of linear battacin lipopeptides against planktonic and mature biofilms of C-albicans
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DOI：
10.1016/j.ejmech.2018.01.023
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发表时间：
2018-02-25
影响因子：
6.7
通讯作者：
Sarojini, Vijayalekshmi
中科院分区：
文献类型：
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作者：
De Zoysa, Gayan Heruka;Glossop, Hugh Douglas;Sarojini, Vijayalekshmi
针对白色念珠菌等病原真菌，需要新型的抗真菌药物。我们报道了巴沙星脂肽抗生素的抗念珠菌活性，其抗真菌活性以前未被发现。在抗念珠菌SC5314的16个巴拉星脂肽中，4-甲基己酰偶联三聚体脂肽13是首选，其MIC值为6.25µM，对小鼠红细胞的溶血作用可忽略不计。在酸性条件下，该脂肽的效价得以保持。此外，两性霉素B在其非溶血浓度下的抗真菌活性进一步增强。在这里，我们首次证明了巴拉星脂肽可以防止白色念珠菌生物被膜的定植，并抑制这种真菌病原体的预先形成的生物被膜。XTT生物被膜试验表明，13能抑制白色念珠菌生物膜在其最低抑菌浓度(MIC)(6.25微米)下的定植，并在较高浓度下，可根除24小时(25微米)和48小时(62.5微米)的预制生物膜。通过比较，我们发现，在更低的浓度下，两性霉素可以阻止生物膜的定植(0.78µM)，并抑制24小时的预制生物膜(6.25 AM)，而对48小时的预制生物膜则完全无效。因此，脂肽13在清除更成熟的白色念珠菌生物被膜方面比两性霉素更有效。通过模拟真菌膜的脂泡比色法验证了化合物13的膜溶解作用机理，其中化合物13通过多肽相互作用使悬浮囊泡立即发生深紫色到红色的转变。此外，暴露于13的白色念珠菌细胞的透射电子显微镜图像显示，细胞膜明显破坏。有趣的是，化合物13以浓度依赖的方式增加内源活性氧物种(ROS)的生成。在抗氧化剂抗坏血酸的存在下，ROS的产生减少，但抗真菌活性保持不变，这可能表明ROS的产生是脂肽13引起的膜溶解的次要作用。在最高测试浓度(1 MM)下，脂肽对小鼠红细胞无溶血作用。(C)2018年爱思唯尔·马森SAS。版权所有。
Novel antifungal agents are required against pathogenic fungi such as Candida albicans. We report the anticandidal activity of battacin lipopeptide antibiotics with previously unexplored antifungal activity. From amongst sixteen battacin lipopeptides tested against C. alibicans (SC5314) the 4-methyl hexanoyl conjugated trimeric lipopeptide 13 emerged as the lead candidate with a MIC of 6.25 mu M and negligible haemolysis of mouse red blood cells. The potency of this lipopeptide was maintained under acidic conditions. Additionally, antifungal activity was further enhanced with amphotericin B at its non haemolytic concentrations. Herein we have demonstrated for the first time that battacin lipopeptides prevent C albicans biofilm colonisation as well as inhibit pre-formed biofilms of this fungal pathogen. XTT biofilm assays revealed that 13 prevented colonisation of C albicans biofilms at its MIC (6.25 mu M) and, at a higher concentration, eradicated 24 h (25 mu M) and 48 h (62.5 mu M) old preformed biofilms. In comparison, we found that amphotericin at much lower concentrations prevented biofilm colonisation (0.78 mu M) and inhibited 24 h old preformed biofilms (6.25 AM), however was completely inactive against 48 h old preformed biofilms. Thus, lipopeptide 13 is more effective than amphotericin at eradicating more mature C albicans biofilms. The membrane lytic mechanism of action of compound 13 was validated by a colorimetric assay using lipid vesicles mimicking fungal membranes in which compound 13 effected an immediate dark purple to red colour transition of suspended vesicles upon peptide interaction. In addition, TEM images of C. albicans cells exposed to 13 showed clearly disrupted cellular membranes. Interestingly, compound 13 increased the endogenous generation of reactive oxygen species (ROS) in a concentration dependent manner. In the presence of an antioxidant, ascorbic acid, ROS production was diminished yet antifungal activity persisted, possibly indicating that ROS production is a secondary effect from membrane lysis caused by lipopeptide 13. The lipopeptide was non-haemolytic against mouse red blood cells at the highest tested concentration (1 mM). (C) 2018 Elsevier Masson SAS. All rights reserved.