Teasaponin induces reactive oxygen species-mediated mitochondrial dysfunction in Candida albicans

茶皂素诱导活性氧产生介导白色念珠菌线粒体功能障碍

Candida albicans is the most prevalent commensal fungus and readily causes invasive fungal infection in immunocompromised individuals. Teasaponin(TS), a natural product generally regarded as safe, has been reported to inhibit filamentation of C. albicans. This study found that TS could exert moderate fungicidal activity against C. albicans, and the mode of action was further explored. The minimum fungicidal concentration(MFC) was determined by the broth microdilution method. The colony counting method was used to determine the time-killing curve of TS against C. albicans in every 2 h. The effect of TS on the content of intracellular reactive oxygen species(ROS) in C. albicans was analyzed by 2′,7′-dichlorofluorescin diacetate(DCFH-DA) staining, and the mitochondrial membrane potential(mtΔψ) was determined by rhodamine123(RH123) staining. An ATP assay kit was utilized to determine the intracellular ATP levels after TS treatment. Results showed that TS-induced ROS accumulation and mitochondrial dysfunction contributed to the death of C. albicans cells. Further research demonstrated that VC could reinforce the fungicidal ability of TS. On the contrary, VE could antagonize the function of TS against C. albicans, which might guide the clinical application of TS. The results preliminarily elucidated the potential mechanisms of TS against C. albicans and might provide a potential option for the treatment of clinical Candida.

白色念珠菌是目前最常见的共生真菌,在免疫功能低下的个体中很容易引起侵袭性真菌感染。茶皂素(TS)是一种安全的天然产物,已有报道可以抑制白色念珠菌的丝状生长。本研究发现TS对白色念珠菌具有中度的杀菌作用,并进一步探索其杀菌机制。采用微量肉汤稀释法测定最小杀菌浓度(MFC)。采用菌落计数法,测定TS对白色念珠菌的杀菌曲线。采用2′,7′-二氯二氢荧光素双乙酸(DCFH-DA)染色法分析TS对白念珠菌内活性氧(ROS)含量的影响,使用罗丹明123染色法测定线粒体膜电位。使用ATP检测试剂盒测定TS处理后白念珠菌内ATP水平。结果表明,TS诱导的ROS积累和线粒体功能障碍导致白念珠菌死亡。进一步的研究表明,维生素C可以加强TS的抗菌能力,相反维生素E拮抗TS杀伤白念珠菌的功能,这可以指导临床TS的应用。研究结果初步阐明了TS杀伤白念珠菌的机制,并提供了一个治疗临床念珠菌药物选择。