Saarvienin A-A Novel Glycopeptide with Potent Activity against Drug-Resistant Bacteria.

A member of a new family of glycopeptides, named saarvienin A, was isolated from a rare actinomycete Amycolatopsis sp. YIM10. Extensive NMR and MS analyses revealed a halogenated peptide core comprising four amino acids cyclized via a ureido linkage with an exocyclic 2-hydroxy-3-(4-hydroxyphenyl)propyl residue connected to a five-sugar/aminosugar chain. Two of the three aminosugars constitute the N-methylated and N,O-dimethylated derivatives of eremosamine (4-epi-vancosamine) that have not been reported in any natural product. Saarvienin A exhibits potent activity against a range of Gram-positive bacteria, effectively overcoming resistance to several frontline antibiotics in clinical isolates. It demonstrates an eight-fold reduction in minimum inhibitory concentrations (MICs) against methicillin-resistant, vancomycin-intermediate, and daptomycin-resistant Staphylococcus aureus compared to vancomycin.