Pentaminomycins F and G, Nonribosomal Peptides Containing 2-Pyridylalanine
Daniel Carretero‐Molina, Francisco Javier Ortiz‐López, Jesús Martı́n, Ignacio González, Marina Sánchez‐Hidalgo, Fernando Román‐Hurtado, Caridad Díaz, Mercedes de la Cruz, Olga Genilloud, Fernando Reyes
Abstract
Pentaminomycins F–H (1–3), a group of three new hydroxyarginine-containing cyclic pentapeptides, were isolated from cultures of a Streptomyces cacaoi subsp. cacaoi strain along with the known pentaminomycins A–E. The structures of the new peptides were determined by a combination of mass spectrometry, NMR, and Marfey’s analyses. Pentaminomycins F (1) and G (2) were shown to contain the rare amino acid 3-(2-pyridyl)-alanine. This finding represents the first reported examples of nonribosomal peptides containing this residue. The ldlld chiral sequence found for the three compounds was in agreement with that reported for previously isolated pentaminomycins and consistent with the epimerization domains present in the putative nonribosomal peptide synthetase (NRPS) biosynthetic gene cluster.