Profiling the Cymbopogon nardus Ethanol Extract and Its Antifungal Potential against Candida Species with Different Patterns of Resistance

The essential oil of Cymbopogon nardus, citronella, has been extensively studied. However, the chemical and biological properties of the ethanolic extract (EE) of C. nardus have not been evaluated. The aim of this study was to characterize the chemical composition of the EE of C. nardus and its active fraction (FrD). Moreover, the cytotoxic and antifungal properties of these extracts against Candida species with different resistance profiles to conventional drugs were evaluated. The compounds identified in EE were mono-C- and di-C-glycosyl flavones and phenylpropanoid glycosides. Phenylpropanoid glycosides were identified in FrD. EE showed antifungal activity, with minimum inhibitory concentration (MIC) values ranging from 62. 5 to 500 µg mL-1. FrD was more effective against C. glabrata, as evidenced by the lowest MIC value (15. 6 µg mL-1). EE inhibited yeast growth similar to amphotericin-B, as demonstrated by similar time-kill curves. EE inhibited C. albicans hyphae formation and mature biofilm of C. albicans, C. krusei and C. parapsilosis. The results of the chemical and biological analyses of EE and its fractions provided novel information and may contribute to control of infections caused by Candida species.

香茅（Cymbopogon nardus）精油已被广泛研究，但该物种的乙醇提取物（ethanolic extract, EE）的化学与生物学特性尚未得到系统评估。本研究旨在表征香茅乙醇提取物（EE）及其活性组分FrD的化学组成；此外，本研究还评估了上述提取物对具有不同传统药物耐药谱的念珠菌（Candida）的细胞毒性与抗真菌活性。从乙醇提取物中鉴定出的化合物包括单-C-糖苷基黄酮、双-C-糖苷基黄酮以及苯丙素苷类成分；活性组分FrD中鉴定出苯丙素苷类成分。乙醇提取物展现出抗真菌活性，其最低抑菌浓度（minimum inhibitory concentration, MIC）范围为62.5~500 μg·mL⁻¹。活性组分FrD对光滑念珠菌（Candida glabrata, C. glabrata）的抑制效果更为显著，最低抑菌浓度低至15.6 μg·mL⁻¹。乙醇提取物对酵母菌的生长抑制效果与两性霉素B（amphotericin-B）相近，二者的时间杀菌曲线具有高度相似性。此外，乙醇提取物可抑制白念珠菌（Candida albicans, C. albicans）的菌丝形成，同时对白念珠菌、克柔念珠菌（Candida krusei, C. krusei）以及近平滑念珠菌（Candida parapsilosis, C. parapsilosis）的成熟生物膜均产生抑制作用。本研究对乙醇提取物及其组分的化学与生物学分析结果提供了全新的科学数据，可为念珠菌属感染的防控工作提供重要参考依据。