School of Chinese Medicine
Leigong Mountain is an area in the Southwest of China where there is a high incidence rate of athlete's foot, but the Miao people, a Chinese minority who reside in this mountainous area have suffered less from this disease due to their use of the herbal medicine Isodon flavidus (Hand.-Mazz.) H. Hara.
Aim of the study
The present study is to identify the active chemical constituents responsible for antifungal effects of the folk medicine plant.
Materials and methods
The natural compounds were separated from the methanol extract of the twigs and leaves of I. flavidus by phytochemical study using chromatographic methods, and their chemical structures were determined by analysis of the spectroscopic data including 1D and 2D NMR spectra. The absolute configuration of fladin A (1) was further confirmed by X-ray crystallographic analysis. The compounds were evaluated for their antifungal activity against the athlete's foot fungus Trichophyton rubrum. They were further evaluated for their antimicrobial and anti-biofilm activity against the dental pathogens Streptococcus mutans, Porphyromonas gingivalis and Candida albicans.
Phytochemical and biological studies of I. flavidus led to the discovery of two antifungal compounds, fladin A (1) and lophanic acid (2). Fladin A (1) is a novel diterpene with an unprecedented cyclic ether group formed between C-4 and C-9. Lophanic acid (2) displayed inhibition activity against the athlete's foot fungus Trichophyton rubrum with an MIC value of 7.8 μg/mL, and fladin A (1) also showed inhibition activity against the fungus with a MIC value of 62.5 μg/mL.
Our identification of two antifungal compounds provided strong evidence for the Miao people to use I. flavidus as a medicinal plant for treatment of athlete's foot disease. The very different chemical structures of the active compounds from those in the market presents them as potential antifungal lead compounds for follow-up study.
Antifungal activity, Fladin A, Isodon flavidus, Isolation, Lophanic acid, Structure identification
Source Publication Title
Journal of Ethnopharmacology
© 2016 Elsevier Ireland Ltd. All rights reserved.
This project was funded by the National Natural Science Foundation of China (Nos. 81260635 and 81560709), the Technology Fund of Guizhou Province (Nos. 2009-700122 and 2015-3032), Faculty Research Grant of Hong Kong Baptist University (FRG2/14-15/047), and HKBU Interdisciplinary Research Matching Scheme of Hong Kong Baptist University (RC-IRMS/12-13/03 and RC-IRMS/15-16/02).
Link to Publisher's Edition
Li, J., Li, Q., Guan, Y., Song, X., Liu, Y., Zhang, J., Li, W., Du, J., Zhu, M., Banas, J., Li, X., Pan, L., & Zhang, H. (2016). Discovery of antifungal constituents from the Miao medicinal plant Isodon flavidus. Journal of Ethnopharmacology, 191, 372-378. https://doi.org/10.1016/j.jep.2016.06.046
Additional FilesJA-5193-29195_suppl.doc (5324 kB)