RESUMO
Trichophyton rubrum is a dermatophyte, which can cause infections in human skin, hair and nail. Pothomorphe umbellata (L.) Miq. (Piperaceae) is a native Brazilian plant, in which phytochemical studies have demonstrated the presence of steroids, 4-nerolidylcatechol, sesquiterpenes and essential oils. The objective of this study was to analyze the in vitro activity of extracts and fractions of P. umbellata on resistant strains of T. rubrum. The microdilution plate method was utilized to test Tr1, H6 and ΔTruMDR2 strains of T. rubrum; ΔTruMDR2 strain was obtained from H6 by TruMDR2 gene rupture, which is involved in multiple drugs resistance. The highest antifungal activity to all strains was observed for dichloromethane and hexane fractions of the 70% ethanolic extract which showed minimal inhibitory concentration (MIC) and minimal fungicide concentration (MFC) of 78.13 µg/mL. This antifungal activity was also obtained by 70% ethanolic extract, which presented MIC and MFC of 78.13 µg/mL to ΔTruMDR2, whereas the MIC values for Tr1 and H6 were 78.13 and 156.25 µg/mL, respectively. Our results suggest the potential for future development of new antifungal drugs from P. umbellata, especially to strains presenting multiple resistance.