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。然而，目前尚未对香茅乙醇提取物（EE）的化学与生物学特性开展相关评价。本研究旨在分析鉴定香茅乙醇提取物及其活性组分FrD的化学成分；此外，本研究还评价了上述提取物针对那些对传统抗真菌药物具有不同耐药谱的念珠菌属（Candida）菌株的细胞毒性与抗真菌活性。
乙醇提取物中鉴定出的化合物为单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中则检测出苯丙素苷类化合物。
乙醇提取物展现出抗真菌活性，最低抑菌浓度（MIC）范围为62.5~500 μg·mL⁻¹。活性组分FrD对光滑念珠菌（C. glabrata）的抑制效果更为显著，其最低抑菌浓度低至15.6 μg·mL⁻¹。
乙醇提取物对酵母菌生长的抑制效果与两性霉素B（amphotericin-B）相近，二者的时间杀菌曲线结果可佐证这一点。乙醇提取物可抑制白念珠菌（C. albicans）菌丝形成，同时还能抑制白念珠菌、克柔念珠菌（C. krusei）及近平滑念珠菌（C. parapsilosis）的成熟生物膜。
本次针对乙醇提取物及其组分的化学与生物学分析结果具有新颖性，可为念珠菌属感染的防控工作提供参考依据。