Published in:
Open Access
01-12-2015 | Research
Antifungal mode of action of macrocarpal C extracted from Eucalyptus globulus Labill (Lan An) towards the dermatophyte Trichophyton mentagrophytes
Authors:
Jack Ho Wong, Kit-Man Lau, Yu-On Wu, Ling Cheng, Chun-Wai Wong, David Tai-Wai Yew, Ping-Chung Leung, Kwok-Pui Fung, Mamie Hui, Tzi-Bun Ng, Clara Bik-San Lau
Published in:
Chinese Medicine
|
Issue 1/2015
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Abstract
Background
The fresh leaves of Eucalyptus globulus Labill. (Lan An) have been used in Chinese medicine for many years to treat dermatomycosis. Macrocarpal C was isolated from this herb and identified as its major antifungal component by bioassay-guided purification. This study aims to investigate the antifungal activity of macrocarpal C against Trichophyton mentagrophytes, which can cause tinea pedis.
Methods
Fresh leaves of E. globulus were extracted with 95 % ethanol, and the resulting ethanolic extracts were dried before being partitioned with n-hexane. The n-hexane layer was then subjected to chromatographic purification to give macrocarpal C. The antifungal minimum inhibitory concentration (MIC) of macrocarpal C was determined using the standard M38-A2 method described by the Clinical Laboratory Standards Institute (CLSI). The mode of action of macrocarpal C was elucidated using three in vitro assays, including (1) a fungal membrane permeability test using SYTOX® Green; (2) a reactive oxygen species (ROS) production test using 5-(and-6)-carboxy-2′,7′-dihydrodichlorofluorescein diacetate as a cell-permeable fluorogenic probe; and (3) a DNA fragmentation test based on terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) detection. Terbinafine hydrochloride and nystatin were used as positive controls.
Results
The suppression in the growth of T. mentagrophytes following its treatment with macrocarpal C was associated with an increase in the permeability of the fungal membrane (P = 0.0043 when compared to control); an increase in the production of intracellular ROS (P = 0.0063); and the induction of apoptosis as a consequence of DNA fragmentation (P = 0.0007).
Conclusion
This study demonstrated that the antifungal action of macrocarpal C was associated with increases of membrane permeability, intracellular ROS and DNA fragmentation.