Utahmycin C, a new glycosylated derivative of a rare azaanthraquinone produced by Streptomyces sp. YD248.

Chemical investigation of Streptomyces sp. YD248 led to the isolation of utahmycin C (1), a new glycosylated member of the rare bacterial 1,3-dimethyl-2-azaanthraquinone family. Its structure was established by NMR spectroscopy and high-resolution mass spectrometry, revealing a β-D-glucuronic acid substituent attached to the azaanthraquinone core. Unusual long-range 5J HMBC correlations prompted validation by density functional theory (DFT) through NMR chemical shift calculations, which showed excellent agreement with the experimental data. Bioinformatics analysis identified a biosynthetic gene cluster (BGC) homologous to the reported Erd gene cluster associated with utahmycin A biosynthesis. This study expands the structural diversity of bacterial azaanthraquinones.