Antifungal activity and potential inhibitory mechanism of Huangqin decoction on Trichophyton mentagrophytes
Trichophyton mentagrophytes (T. mentagrophytes) is a prevalent pathogen that causes human and animal dermatophytosis. The clinical treatment of these infections is challenging due to the prolonged treatment duration, limited efficacy, antifungal resistance and side effects of existing drugs. It has been reported that the classic Traditional Chinese medicine (TCM) prescription Huangqin decoction (HQD) along with its principal ingredients could exhibit antifungal properties. Given the valued advantages of TCM such as broad-spectrum antifungal activity, low incidence of drug resistance and low toxicity, this study investigated the antifungal activity of HQD against T. mentagrophytes and explored the potential inhibitory mechanism, aimed to provide new clues for the treatment of dermatophytosis. By detecting minimal inhibitory concentration (MIC) using the broth microdilution method, the result showed that HQD could significantly inhibit the growth of T. mentagrophytes, with a MIC of 3.13 mg/mL. The transcriptome sequencing and quantitative real-time PCR (qRT-PCR) technology were combined to shed light on the complicated adaptive responses of T. mentagrophytes upon HQD. The results demonstrated that a total of 730 differentially expressed genes (DEGs) were detected in T. mentagrophytes after HQD exposure, of which 547 were up-regulated and 183 were down-regulated. These DEGs were abundant in “single-organism metabolic process”, “catalytic activity” and “oxidoreductase activity”, and were significantly enriched in seven signaling pathways including glutathione metabolism, DNA replication, glyoxylate and dicarboxylate metabolism, taurine and hypotaurine metabolism, carotenoid biosynthesis, ubiquitin mediated proteolysis, and cyanoamino acid metabolism. The results of transcriptome profiling were verified using qRT-PCR for a subset of 10 DEGs. The overall evidence indicated that HQD had a significant anti-dermatophyte activity through the modulation of glutathione metabolism by regulating GST, ?-GT genes, the inhibition of DNA replication pathway by downgrading MCM3, MCM5, RNaseH1 genes, and the repressed expression of PSD gene related to phospholipid synthesis in T. mentagrophytes. Overall design: RNA-seq was performed in Trichophyton mentagrophytes (XM109) treated with or without HQD to detect the differential genes that HQD may affect.