Sch725674 is a novel macrolide isolated from the culture of an Aspergillus sp. by a team of researchers at Schering-Plough in 2005. The compound showed inhibitory activity against Saccharomyces cerevisiae (PM503) and Candida albicans (C43) with MICs of 8 and 32 mg/ml (micrograms per milliliter), respectively. The 2D structure of Sch725674 was rigorously assigned via 2D NMR data analyses including HSQC, HSQC-TOCSY, and HMBC. However, the stereochemistry of the four oxygenated methine carbon atoms could not be assigned due to the limited amount of sample isolated (about 1 mg). Fourteen-membered macrolactones lacking methyl substitution like Sch725674 are very rare in nature, which makes stereoisomer library generation more interesting in the context of structural assignment and biological evaluation.
Journal of Antibiotics 58 (8): 535-538, 2005.