In vitro characterization, ADME analysis, histological and toxicological evaluation of BM1, a macrocyclic amidinourea active against azole-resistant Candida strains

BACKGROUND: Among the opportunistic fungi, Candida species represent one of the most common causes of nosocomial bloodstream infections. The large use of antifungal agents, most of them launched on the market more than twenty years ago, led to the selection of drug-resistant or even multidrug-resistant fungi. In the last years, we described a novel class of antifungal macrocyclic compounds bearing an amidinourea moiety, highly active against various azole-resistant Candida strains. OBJECTIVE: In this study, one representative of this family, compound BM1, has been investigated on its in vitro activity against various Candida species, including C. auris isolates, its interaction with the ABC transporter CDR6 and its in vivo distribution and safety. METHODS: In vitro assays (CYP inhibition, microsomal stability, permeability, spot assays) have been used to collect chemical and biological data; animal models (rat) paired with LC-MS analysis have been exploited to evaluate in vivo toxicology, pharmacokinetics, and distribution. RESULTS: Our research highlights the low in vivo toxicity profile of BM1, its affinity for the renal system in rats and its good absorption, distribution, metabolism, and excretion (ADME) features. Our compound preserves a potent activity also against azole-resistant fungal strains, including C. auris isolates and CDR6-overexpressing strains. CONCLUSIONS: We confirmed low MICs against several Candida species, including preliminary data versus C. auris. The good ADME and biochemical characteristics make BM1 suitable and safe for daily administration and particularly indicated to treat renal infections. These data make BM1 and its derivatives a novel promising antifungal class.