Izupeptins A and B, new glycopeptide antibiotics produced by an actinomycete

In the course of screening for new high molecular weight peptidoglycan synthesis inhibitors, izupeptins A and B, antibiotics active against Gram-positive bacteria including methicillin-resistant Staphylococci and Clostridium were discovered. The antibiotics were found to be new members of the glycopeptide antibiotic family, namely of the vancomycin type, based on chemical and spectroscopic data. The molecular weight of izupeptin A was determined to be 1,475 by SI (secondary ion)-MS (integer molecular weight, 1,473), and it contains two chlorine atoms.