Saarvienin A—A Novel Glycopeptide with Potent Activity against Drug‐Resistant Bacteria

Abstract 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.