Introduction. Trichophyton rubrum is a major causative agent of superficial dermatomycoses such as onychomycosis and tinea pedis. Huangqin decoction (HQD), as a classical traditional Chinese medicine formula, was found to inhibit the growth of common clinical dermatophytes such as T. rubrum in our previous drug susceptibility experiments. Hypothesis/Gap Statement. The antifungal activity and potential mechanism of HQD against T. rubrum have not yet been investigated. Aim. The aim of this study was to investigate the antifungal activity and explore the potential mechanism of action of HQD against T. rubrum. Methodology. The present study was performed to evaluate the antifungal activity of HQD against T. rubrum by determination of minimal inhibitory concentrations (MICs), minimal fungicidal concentrations (MFCs), mycelial growth, biomass, spore germination and structural damage, and explore its preliminary anti-dermatophyte mechanisms by sorbitol and ergosterol assay, HPLC-based ergosterol test, enzyme-linked immunosorbent assay and mitochondrial enzyme activity test. Results. HQD was able to inhibit the growth of T. rubrum significantly, with an MIC of 3.125 mg ml−1 and an MFC of 12.5 mg ml−1. It also significantly inhibited the hyphal growth, conidia germination and biomass growth of T. rubrum in a dose-dependent manner, and induced structural damage in different degrees for T. rubrum cells. HQD showed no effect on cell wall integrity, but was able to damage the cell membrane of T. rubrum by interfering with ergosterol biosynthesis, involving the reduction of squalene epoxidase (SE) and sterol 14α-demethylase P450 (CYP51) activities, and also affect the malate dehydrogenase (MDH), succinate dehydrogenase (SDH) and ATPase activities of mitochondria. Conclusion. These results revealed that HQD had significant anti-dermatophyte activity, which was associated with destroying the cell membrane and affecting the enzyme activities of mitochondria.

中文翻译：

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黄芩汤对红色毛癣菌的抗真菌活性及潜在作用机制

介绍。 红色毛癣菌是甲癣和足癣等浅部皮肤真菌病的主要病原体。黄芩汤（HQD）作为经典中药方剂，在前期药敏实验中发现其对红色毛癣菌等临床常见皮肤癣菌的生长具有抑制作用。假设/差距陈述。 HQD 对T. rubrum的抗真菌活性和潜在机制尚未得到研究。目的。本研究的目的是研究 HQD 的抗真菌活性并探讨 HQD 对抗T. rubrum的潜在作用机制。方法。本研究通过测定最低抑菌浓度（MIC）、最低杀菌浓度（MFC）、菌丝生长、生物量、孢子萌发和结构损伤等指标来评价HQD对红色毛癣菌的抗真菌活性，并探讨其初步抗真菌活性。通过山梨醇和麦角甾醇测定、基于 HPLC 的麦角甾醇测试、酶联免疫吸附测定和线粒体酶活性测试来确定皮肤癣菌机制。结果。 HQD能够显着抑制红色毛癣菌的生长，MIC为3.125 mg ml -1，MFC为12.5 mg ml -1。它还以剂量依赖的方式显着抑制红色毛癣菌的菌丝生长、分生孢子萌发和生物量生长，并诱导红色毛癣菌细胞不同程度的结构损伤。 HQD 对细胞壁完整性没有影响，但能够通过干扰麦角甾醇生物合成来损伤T. rubrum细胞膜，包括降低角鲨烯环氧酶 (SE) 和甾醇 14α-去甲基酶 P450 (CYP51) 活性，并影响线粒体的苹果酸脱氢酶（MDH）、琥珀酸脱氢酶（SDH）和ATP酶活性。结论。这些结果表明，HQD具有显着的抗皮肤癣菌活性，这与破坏细胞膜并影响线粒体酶活性有关。