title: Antifungal mode of action of macrocarpal C extracted from Eucalyptus globulus Labill (Lan An) towards the dermatophyte Trichophyton mentagrophytes.
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).
  
  
  CONCLUSIONS
  This study demonstrated that the antifungal action of macrocarpal C was associated with increases of membrane permeability, intracellular ROS and DNA fragmentation.
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Jack Ho
authors.initials: JH
authors.lastname: Wong
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Kit-Man
authors.initials: KM
authors.lastname: Lau
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Yu-On
authors.initials: YO
authors.lastname: Wu
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Ling
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Chun-Wai
authors.initials: CW
authors.lastname: Wong
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: David Tai-Wai
authors.initials: DT
authors.lastname: Yew
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Ping-Chung
authors.initials: PC
authors.lastname: Leung
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Kwok-Pui
authors.initials: KP
authors.lastname: Fung
authors.affiliation: Department of Microbiology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Mamie
authors.initials: M
authors.lastname: Hui
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Tzi-Bun
authors.initials: TB
authors.lastname: Ng
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.|State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Clara Bik-San
authors.initials: CB
authors.lastname: Lau