Analysis of chemical composition and in vitro antidermatophyte activity of ethanol extracts of Dryopteris fragrans (L.) Schott.

BACKGROUND

Dryopteris fragrans (L.) Schott is a deciduous perennial herb, which has been used traditionally for treatment of ringworm infections and others skin diseases in the north of China.

OBJECTIVE

To characterize the chemical composition, evaluate the antifungal activity and explore possible mechanisms about action of ethanol extracts of D. fragrans.

METHODS

The chemical components in the ethanol extracts of D. fragrans were detected by high-performance liquid chromatography coupled with electrospray ionization and quadruple time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS). The minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of the ethanol extracts of D. fragrans were determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 method against 62 isolates of dermatophytes. The kinetics of fungal kill, synergy testing by checkerboard dilution and quantitation of sterol by ultra-performance liquid chromatography (UPLC) on Trichophyton rubrum and Trichophyton mentagrophytes were also investigated.

RESULTS

Fourteen derivatives of phloroglucinol were identified in the ethanol extracts of D. fragrans. The MIC of the ethanol extracts of D. fragrans ranged from 0.059 to 3.780 mg/mL while MFC ranged from 0.118 to 3.780 mg/mL. The ethanol extracts of D. fragrans exerted fungicidal activity after 12 h of incubation against Trichophyton rubrum while it required 36 h of incubation against Trichophyton mentagrophytes at concentrations of 8 × MIC. In synergy testing, the interaction between miconazole (MCZ) and terbinafine (TBF) with the ethanol extracts of D. fragrans proved to be indifferent by testing fractional inhibitory concentration (FIC) values. Sterol in samples of fungal cells treated with the ethanol extracts of D. fragrans was significantly reduced.

CONCLUSIONS

The ethanol extracts of D. fragrans had antifungal and fungicidal activity against dermatophytes and was likely a strain-dependent fungicidal agent. Interaction between drugs was indifferent on tested isolates. The inhibition of ergosterol biosynthesis was one of the antifungal mechanisms of the ethanol extracts of D. fragrans. These results showed that the ethanol extracts of D. fragrans could be explored for promising antifungal drugs. Dozens of phloroglucinol derivatives may contribute to high antifungal activity of the ethanol extracts of D. fragrans.