New Antimicrobial Accramycins from Streptomyces sp. MA37 Variant

In our continued desire to isolate more bioactive compounds from the Streptomyces sp. MA37 variant, ΔaccJ, three new accramycin derivatives have been successfully characterised. The structures of accramycin L-N (1–3) were established by high-resolution mass spectrometry and 1D and 2D nuclear magnetic resonance. The antimicrobial evaluation of accramycin L-N against Staphylococcus aureus, Klebsiella pneumoniae, and Enterobacter cloacae showed minimum inhibitory concentration (MIC) values ranging from 0.77 to 13.02 µg/mL. Accramycin L exhibited the most significant activity against S. aureus. In addition, accramycin L-N (1–3) displayed significant activity against K. pneumoniae at the MIC values of 0.81, 0.77, and 0.79 µg/mL, respectively.