Our previously reported efforts to produce an orally active β-1,3-glucan synthesis inhibitor through the semi-synthetic modification of enfumafungin focused on replacing the C2 acetoxy moiety with an aminotetrazole and the C3 glycoside with a N,N-dimethylaminoether moiety. This work details further optimization of the C2 heterocyclic substituent, which identified 3-carboxamide-1,2,4-triazole as a replacement for the aminotetrazole with comparable antifungal activity. Alkylation of either the carboxamidetriazole at C2 or the aminoether at C3 failed to significantly improve oral efficacy. However, replacement of the isopropyl alpha amino substituent with a t-butyl, improved oral exposure while maintaining antifungal activity. These two structural modifications produced MK-5204, which demonstrated broad spectrum activity against Candida species and robust oral efficacy in a murine model of disseminated Candidiasis without the N-dealkylation liability observed for the previous lead.

我们先前报道的通过恩富马芬的半合成修饰来生产口服活性β-1,3-葡聚糖合成抑制剂的努力集中在用氨基四唑代替C2乙酰氧基部分和用N，N-二甲基氨基醚部分代替C3糖苷。这项工作详细介绍了C2杂环取代基的进一步优化，该取代基确定了3-羧酰胺-1,2,4-三唑是具有可比的抗真菌活性的氨基四唑的替代品。C2处的羧酰胺三唑或C3处的氨基醚烷基化均无法显着改善口服功效。但是，用t取代异丙基α-氨基取代基丁基，改善口腔暴露，同时保持抗真菌活性。这两种结构修饰产生了MK-5204，其在散播念珠菌病的鼠模型中证明了针对念珠菌的广谱活性和强大的口服功效，而没有观察到先前铅的N-脱烷基反应。