Planta Med 2012; 78 - PI202
DOI: 10.1055/s-0032-1320890

Anti-dermatophytic activity and the underlying action mechanism of macrocarpal C isolated from Eucalypti Globuli Folium

CBS Lau 1, 2, M Hui 3, TB Ng 4, VKM Lau 1, 2, DYO Wu 1, 2, L Cheng 1, 2, H Wong 4, SMH To 1, 2, CP Lau 1, 2, DTW Yew 4, PC Leung 1, 2, KP Fung 1, 2, 4
  • 1Institute of Chinese Medicine
  • 2State Key Laboratory of Phytochemistry and Plant Resources in West China (CUHK)
  • 3Department of Microbiology
  • 4School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

Eucalypti Globuli Folium (EGF), the fresh leaves of Eucalyptus globules Labill., has long been used in China to treat influenza, headache, cough, eczema and dermatomycosis. The objectives of present study were to identify the active anti-dermatophytic component from EGF using bioassay-guided fractionation, and to reveal the action mechanism of the isolated compound. Our results showed that ethanolic extract of EGF was more potent than its aqueous counterpart in inhibiting the growth of dermatophytes, with MIC values of 3.9µg/ml and 15.6µg/ml on T. mentagrophytes and T. rubrum, respectively. Using bioassay-guided fractionation, macrocarpal C (a formylated phloroglucinol compound) was identified as the active component, with MIC values of 4.3µM and 137.7µM on T. mentagrophytes and T. rubrum, respectively. Further mechanistic study showed that fungal conidia treated with macrocarpal C (0.625-fold to 5-fold of MIC) for 24 or 48 hours had significant increase in SYTOX Green uptake in both dose- and time-dependent manners. This is the first report to demonstrate the inhibition of macrocarpal C on the growth of dermatophytes by destroying the cell integrity and increasing membrane permeability. Therapeutic effect of macrocarpal C on guinea pig model of tinea pedis will be evaluated in the future.