Isolation of coumarins with anti-Trichophyton rubrum activity from Heracleum vicinum Boiss

Heracleum vicinum Boiss., a perennial plant of Angelica in Umbelliferae, is mainly distributed in Sichuan and Hunan of China. Trichophyton rubrum is a common skin fungus causing dermatophyte. The previous experimental study found that the ethanol extract from Heracleum vicinum Boiss. had excellent anti-Trichophyton rubrum activity, especially the ethanol extract further extracted with petroleum ether and dichloromethane has the best antibacterial effect and has good potential for treating dermatophytes. In this study, Heracleum vicinum Boiss. was extracted with ethanol by microwave-assisted ultrasonic extraction method and isolated with silica gel column to obtain a coumarin compound M1-1 by the guidance of anti-Trichophyton rubrum activity, which was characterized by nuclear magnetic resonance spectroscopy(¹³C-NMR), hydrogen nuclear magnetic resonance (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), high-resolution mass spectrometry (HR-ESI-MS), and ultraviolet (UV) and identified as imperatorin and belonged to coumarins, with the minimum inhibitory concentration (MIC) against Trichophyton rubrum of 12.5 μg/mL. According to the discussion on the inhibitory mechanism of the compound, we found that the compound may exert its inhibitory effect by destroying the mycelial membrane and inhibiting the mycelial growth of Trichophyton rubrum. In a word, imperatorin isolated from Heracleum vicinum Boiss. is expected to be used as an antibacterial agent to treat dermatophytes a potential natural compound against Trichophyton rubrum, and a template for drug development of dermatophytes the future.