Saperconazole

Herein we describe the scalable diastereoselective and enantioselective syntheses of eight enantiomers of hydroxy metabolites of saperconazole. The in vitro antifungal activity of the eight stereoisomers (compounds 1–8) was compared against a broad panel of Candida spp. (n=93), Aspergillus spp. (n=10), Cryptococcus spp. (n=19), and dermatophytes (n=27). The four 2S isomers 1–4 of the new agent were generally slightly more active than the four 2R isomers 5–8. All eight isomers were tested in a model of experimental A. fumigatus infection in guinea pigs by intravenous inoculation of the fungal conidia. Treatment doses were 1.25 mg kg−1 and 2.5 mg kg−1 per day. Infection severity was measured in terms of mean survival time (MST) after infection and mean tissue burdens in brain, liver, spleen, and kidney at postmortem examination. Among the eight isomers, the 2S diastereomers 1–4 showed a generally higher level of activity than the 2R diastereomers 5–8, revealing compounds 1 and 4 as the most potent overall in eradicating tissue burden and MST. Compared with reference compounds itraconazole and saperconazole, the hydroxy isomers 1–8 are less potent inhibitors of the growth of A. fumigatus in vitro and of ergosterol biosynthesis in both A. fumigatus and C. albicans.

We studied the inhibitory effects on colony formation by granulocyte-macrophage colony forming units (cfu-gm) of eight azole antifungal agents in vitro. All agents, except fluconazole, inhibited colony formation dose-dependently with 50% inhibitory concentrations (IC50) in the range of 0.78-49 micromol/L in cultures of murine and human bone marrow. For human cells, the IC50 values were 0.553 mg/L for itraconazole, 1.24 mg/L for saperconazole, 2.58 mg/L for clotrimazole, 5.33 mg/L for miconazole, 6.17 mg/L for econazole, 6.27 mg/L for ketoconazole and 8.38 mg/L for oxiconazole. The IC50 of itraconazole for human cfu-gm in vitro was similar to the plasma level of this drug recommended for systemic antifungal therapy (>0.5 mg/L) thus indicating the potential clinical relevance of our data. The IC50 of ketoconazole for human cfu-gm in vitro may be exceeded by plasma levels produced in vivo by high (> or =400 mg) doses, whereas fluconazole failed to reduce colony formation by 50% even at 100 mg/L, a concentration not reached in vivo even after extremely high doses (2000 mg/day). To most of the drugs studied, murine progenitor cells seemed to be less sensitive than the human ones. There was, however, a close correlation between the murine and human log IC50 values of the drugs (r2 = 0.964, P< 0.001), suggesting that cultures of murine bone marrow may be suitable to predict the in-vitro toxicity of azole antifungals to human cfu-gm.