Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Department of Medical Mycology and Parasitology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
J Appl Microbiol. 2020 Dec;129(6):1541-1551. doi: 10.1111/jam.14740. Epub 2020 Jul 9.
Increasing the occurrence of non-albicans Candida species with intrinsic or acquired resistance to antifungals as well as the emergence of multidrug Candida species coupled with the limited antifungal agents challenges the treatment of candidiasis. Consequently, a class of secondary metabolites of plants exhibiting decent antifungal activity. Therefore, this study aimed to evaluate the antifungal potential of various monoterpenes including Carvone, Limonene, Pinene, Menthone, Menthol, Camphor, Thujone, Citronellol, and Piperitone against standard and clinical isolates of Candida.
Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of compounds were determined, using the broth Microdilution method based on M27-A3 protocol documented by clinical laboratory standard institute (CLSI). Amongst the tested monoterpenes, oxygenated terpenoids showed strong antifungal activity. Specifically, alcoholic terpenoids such as (±)-Citronellol possess more efficacy than the corresponding ketonic ones with MICs ranging from 0·03 to 2·00 μl ml (0·16-10·80 mmol l ). Among the examined yeasts, Candida tropicalis was the most susceptible species to (±)-Citronellol. Moreover, the examined monoterpenes successfully inhibited the growth of fluconazole-resistant Candida species. Moreover, statistical analysis showed no statistically significant difference between the (+) and (-) isomers, except for (±)-α-Pienene and (±) Menthone (ρ-value < 0·05).
Among the tested monoterpenes, (±)-Citronellol was the most potent compounds followed by (+)-α-Pinene and Menthol. Considering the significant antifungal activity of the examined monoterpenes, they could be used in controlling or treating candidiasis. Those potent antifungal monoterpenes with GRAS status in addition to their pleasant taste and odour make them appropriate additive or preservative compounds in food and cosmetics products. Furthermore, these data might help researchers to predict EOs antifungal activities, after determining its constituents.
This study provides new information about the antifungal activities of monoterpenes and their isomers presented widely in essential oils. Screening results against pathogenic yeasts confirm the correlation between the chemical structure of tested monoterpenes and their antifungal effects. The present findings might be helpful to anticipate the antifungal activity of essential oils.
具有内在或获得性抗真菌药物耐药性的非白色念珠菌念珠菌物种的发生率增加，以及多药耐药念珠菌物种的出现，加上有限的抗真菌药物，这给念珠菌病的治疗带来了挑战。因此，植物的一类次生代谢产物具有良好的抗真菌活性。因此，本研究旨在评估各种单萜，包括香芹酮、柠檬烯、蒎烯、薄荷酮、薄荷醇、樟脑、侧柏酮、香茅醇和胡椒酮对标准和临床分离的念珠菌的抗真菌潜力。
根据临床和实验室标准协会（CLSI）记录的 M27-A3 协议，使用肉汤微量稀释法测定化合物的最小抑菌浓度（MIC）和最低杀菌浓度（MFC）。在所测试的单萜中，含氧萜类化合物表现出很强的抗真菌活性。具体来说，醇类萜类化合物，如（±）-香茅醇，其功效比相应的酮类化合物更强，MIC 范围为 0.03 至 2.00 μl/ml（0.16-10.80 mmol/l）。在所检查的酵母中，热带念珠菌对（±）-香茅醇最敏感。此外，所检查的单萜成功抑制了氟康唑耐药念珠菌物种的生长。此外，统计分析显示，除了（±）-α-蒎烯和（±）-薄荷酮（ρ 值<0.05）之外，（+）和（-）异构体之间没有统计学上的显著差异。
在所测试的单萜中，（±）-香茅醇是最有效的化合物，其次是（+）-α-蒎烯和薄荷醇。鉴于所测试的单萜具有显著的抗真菌活性，它们可用于控制或治疗念珠菌病。这些具有 GRAS 地位的强效抗真菌单萜，加上它们宜人的味道和气味，使它们成为食品和化妆品产品中合适的添加剂或防腐剂。此外，这些数据可能有助于研究人员在确定其成分后预测精油的抗真菌活性。
本研究提供了关于单萜及其在精油中广泛存在的异构体的抗真菌活性的新信息。对致病性酵母的筛选结果证实了所测试单萜的化学结构与其抗真菌作用之间的相关性。本研究结果可能有助于预测精油的抗真菌活性。
