Discovery of antifungal constituents from the Miao medicinal plant Isodon flavidus

Publication date: 15 September 2016
Source:Journal of Ethnopharmacology, Volume 191
Author(s): Ji-Xin Li, Qi-Ji Li, Yi-Fu Guan, Xun Song, Ya-Hua Liu, Jing-Jie Zhang, Wan-Fei Li, Jiang Du, Min Zhu, Jeffrey A. Banas, Xiao-Nian Li, Lu-Tai Pan, Hong-Jie Zhang
Ethnopharmacological relevanceLeigong 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 studyThe present study is to identify the active chemical constituents responsible for antifungal effects of the folk medicine plant.Materials and methodsThe 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.ResultsPhytochemical 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 7.8μg/mL, and fladin A (1) also showed inhibition activity against the fungus with a MIC value of 62.5μg/mL.ConclusionsOur 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.

Graphical abstract

from #MedicinebyAlexandrosSfakianakis via xlomafota13 on Inoreader http://ift.tt/29oy3Q7
via IFTTT