RESUMO
The antimicrobial drug candidate 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver(I) acetate (SBC3) was evaluated for its ability to function in vivo using larvae of Galleria mellonella. A SBC3 concentration of 25 µg/ml inhibited the growth of Staphylococcus aureus by 71.2% and Candida albicans by 86.2% in vitro. Larvae inoculated with 20 µl of SBC3 solution showed no ill effects up to a concentration of 250 µg/ml but administration of 500 µg/ml resulted in a 40% reduction in larval survival and administration of a dose of 1,000 µg/ml resulted in total larval death at 24 h. Larvae inoculated with S. aureus or C. albicans and subsequently administered SBC3 showed increased survival. Administration of SBC3 to larvae did not boost the insect immune response as indicated by lack of an increase in the density of circulating haemocytes (immune cells). The abundance of a number of proteins involved in the insect immune response was reduced in larvae that received 20 µl SBC3 solution of 100 µg/ml. This is the first demonstration of the in vivo activity of SBC3 against S. aureus and C. albicans and demonstrates that SBC3 does not stimulate a non-specific immune response in larvae.