Chemical modification of dehydrated amino acids in natural antimicrobial peptides by photoredox catalysis

Dehydroalanine (Dha) and dehydrobutyrine (Dhb) are remarkably versatile non-canonical amino acids often found in antimicrobial peptides. Here, we present the selective modification of Dha and Dhb in antimicrobial peptides via photocatalytic activation of organoborates under influence of visible light. Ir(dF(CF3)ppy)2(dtbbpy)PF6 was used as photoredox catalyst in aqueous solutions for the modification of thiostrepton and nisin. The mild conditions and high selectivity for the dehydrated residues, show photoredox catalysis is a promising tool for modification of peptide derived natural products.