Antifungal effects of alpha-terthienyl from Tagetes patula on five dermatophytes

Alpha-terthienyl (αT), a thiophene compound isolated from Tagetes patula (Asteraceae), exhibits antifungal activity towards five strains of dermatophytes (Trichophyton mentagrophytes, T. rubrum, T. violaceum, Epidermophyton floccosum, Microsporum cookei). αT plus UVA irradiation for 90 min acted as a fungistatic at concentrations between 6 μM and 24 μM. Between 1 and 10 days after irradiation, the fungal growth was reduced or arrested with marked responses for T. mentagrophytes, T. rubrum and M. cookei. The ultrastructural events that occur in Trichophyton mentagrophytes after treatment were studied by electron microscopy. In the dark, αT caused no important ultrastructural modifications within the hyphae. After UVA irradiation the photoactive compound caused damage to membranes of the nucleus, mitochondria and endoplasmic reticulum. Plasmolytic and autolytic changes resulted in plasma membrane breakage and in cell wall aberrations. UVA-activated αT would appear to target protein-rich membranes of the dermatophytes.