Antifungal activity of silver salts of Keggin-type heteropolyacids against Sporothrix spp.

Sporotrichosis is a chronic and subacute mycosis causing epidemiological outbreaks involving sick cats and humans in southeastern Brazil. The systemic disease prevails in cats, and in humans, the symptoms are restricted to skin in immunocompetent individuals. Under these conditions, the prolonged treatment of animals and cases of recurrence justify the discovery of new treatments for sporotrichosis. This work addresses the antifungal activity of silver salts of Keggin-type heteropolyacid salts (Ag-HPA salts) such as Ag 3 [PW 12 O 40 ], Ag 6 [SiW 10 V 2 O 40 ], Ag 4 [SiW 12 O 40 ] and Ag 3 [PMo 12 O 40 ] and interactions with the antifungal drugs itraconazole (ITC), terbinafine (TBF) and amphotericin B (AMB) on the yeast and mycelia forms of Sporothrix spp. Sporothrix spp. yeast cells were susceptible to Ag-HPA salts at minimum inhibitory concentration (MIC) values ranging from 8 to 128 μg/mL. Interactions between Ag 3 [PW 12 O 40 ] and Ag 3 [PMo 12 O 40 ] with itraconazole and amphotericin B resulted in higher antifungal activity with a reduction in growth and melanization. Treated cells showed changes in cell membrane integrity, vacuolization, cytoplasm disorder, and membrane detachment. Promising antifungal activity for treating sporotrichosis was observed for the Ag-HPA salts Ag 3 [PMo 12 O 40 ] and Ag 3 [PW 12 O 40 ], which have a low cost, high yield and activity at low concentrations. However, further evaluation of in vivo tests is still required.