Discovery of Antifungal Compounds from Kampo Medicine Against Dermatophytes

BACKGROUND: Kampo medicine mainly contain crude extracts of natural products such as plants, animals, and minerals that are prepared according to classical Kampo methodologies. Since plants synthesize numerous antimicrobial components such as plant defensins, Kampo medicine likely contain potent antimicrobial constituents. We have tested antifungal activity of 61 commercially available Kampo medicines by using micro-broth dilution assay with Trichophyton rubrum (T. rubrum), and found that 7 of them had antifungal activity. Among these 7 Kampo medicines 6 contained Ou-gon which derived from the roots of Scutellaria baicalensis Georgi, and a crude extract of Ou-gon exhibited significant antifungal activity. This study aims to identify antifungal components contained in Ou-gon, and determine their antifungal mechanism. METHODS: T. rubrum, T. mentagrophytes, Aspergillus fumigatus (A. fumigatus) and Candida albicans (C. albicans) were used for antifungal activity assay. The antifungal activity assay was performed by measuring 595 nm absorbance in micro-broth dilution assay. Active components were analyzed by high performance liquid chromatography (HPLC), and identified by liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS/MS). TUNEL assay, SYTOX-Green Uptake analyses, intracellular reactive oxygen species accumulation assay, mitochondrial membrane potential assay, scanning electron microscopy, and transmission electron microscopy were used to clarify the antifungal mechanism of active components. RESULTS: Upon HPLC analysis, two low molecular weight-compounds were isolated having potent antifungal activity. The two compounds were identified as Baicalein and Wogonin by LC-ESI-MS/MS. Baicalein showed antifungal activity for T. rubrum, T. mentagrophytes, A. fumigatus and C. albicans. Wogonin showed antifungal activity for all except C. albicans. Detection of antifungal mechanism of Baicalein and Wogonin suggested that their mode of action is apoptosis-like programmed cell death. CONCLUSION: Baicalein and Wogonin are major compounds to have antifungal activity in Kampo medicine. This study may contribute to the development of new and safe antifungal drugs, especially for the clinical treatment of pathogenic fungal infections. DISCLOSURES: All authors: No reported disclosures.