The photodynamic effect of 5-(4-hydroxy-1-butinyl)-2,2'-bithienyl on dermatophytes

The thiophene 5-(4-hydroxy-1-butinyl)2,2'-bithienyl (BBTOH) strongly inhibited in vitro eight different dermatophytes. Epidermophyton floccosum proved most sensitive to all doses of BBTOH when applied in conjunction with UV-A irradiation. BBTOH also proved quite active against Nannizia cajetani, the only dermatophyte which was also strongly inhibited when treated (50 μg/ml) and kept in the dark. For this reason, N. cajetani was chosen as the test organism for TEM and SEM aimed at determining what treatment-induced ultrastructural and morphological modifications had occurred. TEM revealed that the photoactive mechanism of BBTOH was similar to that of 2,2':5',2''-terthienyl (alpha-T). SEM, on the other hand, showed that early culture aging resulted from treatment.