| Summary: | The genus <i>Fonsecaea</i> is one of the etiological agents of chromoblastomycosis (CBM), a chronic subcutaneous disease that is difficult to treat. This work aimed to evaluate the effects of copper(II), manganese(II) and silver(I) complexes coordinated with 1,10-phenanthroline (phen)/1,10-phenanthroline-5,6-dione (phendione) on <i>Fonsecaea</i> spp. Our results revealed that most of these complexes were able to inhibit <i>F. pedrosoi</i>, <i>F. monophora</i> and <i>F. nubica</i> conidial viability with minimum inhibitory concentration (MIC) values ranging from 0.6 to 100 µM. The most effective complexes against <i>F. pedrosoi</i> planktonic conidial cells, the main etiologic agent of CBM, were [Ag(phen)<sub>2</sub>]ClO<sub>4</sub> and [Ag<sub>2</sub>(3,6,9-tdda)(phen)<sub>4</sub>].EtOH, (tdda: 3,6,9-trioxaundecanedioate), displaying MIC values equal to 1.2 and 0.6 µM, respectively. These complexes were effective in reducing the viability of <i>F. pedrosoi</i> biofilm formation and maturation. Silver(I)-tdda-phen, combined with itraconazole, reduced the viability and extracellular matrix during <i>F. pedrosoi</i> biofilm development. Moreover, both silver(I) complexes inhibited either metallo- or aspartic-type peptidase activities of <i>F. pedrosoi</i> as well as its conidia into mycelia transformation and melanin production. In addition, the complexes induced the production of intracellular reactive oxygen species in <i>F. pedrosoi</i>. Taken together, our data corroborate the antifungal action of metal-phen complexes, showing they represent a therapeutic option for fungal infections, including CBM.
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