Tiwari Pratibha, Singh Divya, Singh Man Mohan
Division of Endocrinology, Central Drug Research Institute, Lucknow 226 001, India.
J Antimicrob Chemother. 2008 Sep;62(3):526-34. doi: 10.1093/jac/dkn223. Epub 2008 Jun 10.
Trichomoniasis is the most common non-viral sexually transmitted disease and is caused by the protozoan Trichomonas vaginalis. In view of increased resistance of the parasite to classical drugs of the metronidazole family, the need for new unrelated agents is increasing. This study evaluates anti-Trichomonas activity of Sapindus saponins, a component of a herbal local contraceptive Consap recently marketed in India.
The parasites were treated with saponins for MIC determination. Anti-Trichomonas activity of the saponins was evaluated using a cytoadherence assay, the substrate gel electrophoresis method and RT-PCR analysis. The effect of saponins on the mitochondrial potential of the host was determined by florescence-activated cell sorter. Actin cytoskeletal staining was used to determine the effect on parasite cytoskeleton.
Using in vitro susceptibility assay, the MIC of Sapindus saponins for T. vaginalis (0.005%) was found to be 10-fold lower than its effective spermicidal concentration (0.05%). Saponins concentration dependently inhibited the ability of parasites to adhere to HeLa cells and decreased proteolytic activity of the parasite's cysteine proteinases. This was associated with decreased expression of adhesin AP65 and membrane-expressed cysteine proteinase TvCP2 genes. Saponins produced no adverse effect on host cells in mitochondrial reduction potential measurement assay. Saponins also reversed the inhibitory mechanisms exerted by Trichomonas for evading host immunity. Early response of saponins to disrupt actin cytoskeleton in comparison with their effect on the nucleus suggests a membrane-mediated mode of action rather than via induction of apoptosis.
Findings demonstrate the potential of Sapindus saponins for development as a microbicidal contraceptive for human use. Further studies are required to evaluate its microbicidal activity against other sexually transmitted infections.
滴虫病是最常见的非病毒性传播疾病，由原生动物阴道毛滴虫引起。鉴于该寄生虫对甲硝唑类传统药物的耐药性增加，对新型非相关药物的需求日益增长。本研究评估了无患子皂苷的抗滴虫活性，无患子皂苷是印度最近上市的一种草药局部避孕药Consap的成分。
用皂苷处理寄生虫以测定最低抑菌浓度（MIC）。使用细胞粘附试验、底物凝胶电泳法和逆转录聚合酶链反应（RT-PCR）分析评估皂苷的抗滴虫活性。通过荧光激活细胞分选仪测定皂苷对宿主线粒体电位的影响。使用肌动蛋白细胞骨架染色来确定对寄生虫细胞骨架的影响。
通过体外药敏试验，发现无患子皂苷对阴道毛滴虫的MIC（0.005%）比其有效的杀精浓度（0.05%）低10倍。皂苷浓度依赖性地抑制寄生虫粘附HeLa细胞的能力，并降低寄生虫半胱氨酸蛋白酶的蛋白水解活性。这与粘附素AP65和膜表达半胱氨酸蛋白酶TvCP2基因的表达降低有关。在线粒体还原电位测量试验中，皂苷对宿主细胞没有产生不良影响。皂苷还逆转了滴虫为逃避宿主免疫而施加的抑制机制。与皂苷对细胞核的影响相比，其对肌动蛋白细胞骨架破坏的早期反应表明其作用模式是膜介导的，而非通过诱导细胞凋亡。
研究结果表明无患子皂苷有开发成为人类用杀微生物避孕药的潜力。需要进一步研究以评估其对其他性传播感染的杀微生物活性。
