Enhanced Molecular Networking Shows sp. V1 as a Factory of Antioxidant Proline-Rich Peptides.

Two linear proline-rich peptides (-), bearing an N-terminal pyroglutamate, were isolated from the marine bacterium sp. V1, associated with the marine sponge , collected in the volcanic CO vents in Ischia Island (South Italy). Peptide production was triggered at low temperature following the one strain many compounds (OSMAC) method. Both peptides were detected together with other peptides (-) via an integrated, untargeted MS/MS-based molecular networking and cheminformatic approach. The planar structure of the peptides was determined by extensive 1D and 2D NMR and HR-MS analysis, and the stereochemistry of the aminoacyl residues was inferred by Marfey's analysis. Peptides - are likely to arise from V1 tailor-made proteolysis of tryptone. Peptides and were shown to display antioxidant properties in the ferric-reducing antioxidant power (FRAP) assay.