Abstract：
BACKGROUND: The development of multidrug resistance (MDR) associated with the overexpression of the efflux transporters Mdr1 and Cdr1 in Candida species impedes antifungal therapies. The urgent need for novel agents able to inhibit the function of both pumps, led us to evaluate this property in 137 extracts obtained from Argentinian plants.
METHODS: The ability of the extracts to reverse efflux pump-mediated MDR was determined with an agar chemosensitization assay using fluconazole (FCZ) resistant Mdr1- and Cdr1-overexpressing clinical isolates of Candida albicans and Candida glabrata as well as Saccharomyces cerevisiae strains selectively expressing Mdr1 (AD/CaMDR1) or Cdr1 (AD/CaCDR1). The resistance-reversing activity of the most potent extracts was further confirmed using a Nile Red accumulation assay.
RESULTS: Fifteen plant extracts overcame the FCZ resistance of Candida albicans 1114, which overexpresses CaMdr1 and CaCdr1, and AD/CaMDR1, with those from Acalypha communis and Solanum atriplicifolium being the most effective showing 4- to 16-fold reversal of resistance at concentrations ≥ 25 µg/mL. Both extracts, and to a lesser extent that from Pterocaulon alopecuroides, also restored FCZ sensitivity in CgCdr1-overexpressing C. glabrata 109 and in AD/CaCDR1 with fold reversal values ranging from 4 to 32 and therefore demonstrating a dual effect against Mdr1 and Cdr1. Both, A. communis and S. atriplicifolium extracts at concentrations ≥ 12.5 and ≥ 25 µg/mL, respectively, increased the intracellular Nile Red accumulation in all yeast strains overexpressing efflux pumps.
CONCLUSIONS: The non-toxic and highly active extracts from A. communis and S. atripicifolium, provide promising sources of compounds for potentiating the antifungal effect of FCZ by blocking the efflux function of Mdr1 and Cdr1 transporters.
METHODS: The ability of the extracts to reverse efflux pump-mediated MDR was determined with an agar chemosensitization assay using fluconazole (FCZ) resistant Mdr1- and Cdr1-overexpressing clinical isolates of Candida albicans and Candida glabrata as well as Saccharomyces cerevisiae strains selectively expressing Mdr1 (AD/CaMDR1) or Cdr1 (AD/CaCDR1). The resistance-reversing activity of the most potent extracts was further confirmed using a Nile Red accumulation assay.
RESULTS: Fifteen plant extracts overcame the FCZ resistance of Candida albicans 1114, which overexpresses CaMdr1 and CaCdr1, and AD/CaMDR1, with those from Acalypha communis and Solanum atriplicifolium being the most effective showing 4- to 16-fold reversal of resistance at concentrations ≥ 25 µg/mL. Both extracts, and to a lesser extent that from Pterocaulon alopecuroides, also restored FCZ sensitivity in CgCdr1-overexpressing C. glabrata 109 and in AD/CaCDR1 with fold reversal values ranging from 4 to 32 and therefore demonstrating a dual effect against Mdr1 and Cdr1. Both, A. communis and S. atriplicifolium extracts at concentrations ≥ 12.5 and ≥ 25 µg/mL, respectively, increased the intracellular Nile Red accumulation in all yeast strains overexpressing efflux pumps.
CONCLUSIONS: The non-toxic and highly active extracts from A. communis and S. atripicifolium, provide promising sources of compounds for potentiating the antifungal effect of FCZ by blocking the efflux function of Mdr1 and Cdr1 transporters.
摘要：
背景：与念珠菌外排转运蛋白Mdr1和Cdr1的过表达相关的多药耐药性（MDR）的发展阻碍了抗真菌治疗。迫切需要能够抑制两种泵功能的新型药剂，带领我们从阿根廷植物中获得的137种提取物中评估了这种特性。
方法：使用氟康唑（FCZ）抗性的Mdr1-和Cdr1过表达的白色念珠菌和光滑念珠菌的临床分离株以及选择性表达Mdr1（CDAD/CaR1）或Cdr1（CDrR1）的酿酒酵母菌株，通过琼脂化学增敏试验确定提取物逆转外排泵介导的MDR的能力。使用尼罗红积累测定进一步证实了最有效的提取物的抗性逆转活性。
结果：15种植物提取物克服了白色念珠菌1114的FCZ抗性，白色念珠菌1114的FCZ抗性过度表达CaMdr1和CaCdr1，以及AD/CaMDR1，其中来自Acalyfacommunis和Solanum的植物提取物在浓度≥25µg/mL时表现出4至16倍的抗性逆转。两种提取物，在较小程度上，还恢复了CgCdr1过表达的光滑梭菌109和AD/CaCDR1中的FCZ敏感性，其倍数逆转值为4至32，因此显示出对Mdr1和Cdr1的双重作用。两者,A.communis和S.atriplicifolium提取物浓度≥12.5和≥25µg/mL，分别,在所有过表达外排泵的酵母菌株中增加了细胞内尼罗红的积累。
结论：来自A.communis和S.atripiffolium的无毒和高活性提取物，通过阻断Mdr1和Cdr1转运蛋白的外排功能，为增强FCZ的抗真菌作用提供了有希望的化合物来源。
方法：使用氟康唑（FCZ）抗性的Mdr1-和Cdr1过表达的白色念珠菌和光滑念珠菌的临床分离株以及选择性表达Mdr1（CDAD/CaR1）或Cdr1（CDrR1）的酿酒酵母菌株，通过琼脂化学增敏试验确定提取物逆转外排泵介导的MDR的能力。使用尼罗红积累测定进一步证实了最有效的提取物的抗性逆转活性。
结果：15种植物提取物克服了白色念珠菌1114的FCZ抗性，白色念珠菌1114的FCZ抗性过度表达CaMdr1和CaCdr1，以及AD/CaMDR1，其中来自Acalyfacommunis和Solanum的植物提取物在浓度≥25µg/mL时表现出4至16倍的抗性逆转。两种提取物，在较小程度上，还恢复了CgCdr1过表达的光滑梭菌109和AD/CaCDR1中的FCZ敏感性，其倍数逆转值为4至32，因此显示出对Mdr1和Cdr1的双重作用。两者,A.communis和S.atriplicifolium提取物浓度≥12.5和≥25µg/mL，分别,在所有过表达外排泵的酵母菌株中增加了细胞内尼罗红的积累。
结论：来自A.communis和S.atripiffolium的无毒和高活性提取物，通过阻断Mdr1和Cdr1转运蛋白的外排功能，为增强FCZ的抗真菌作用提供了有希望的化合物来源。
