Pentadecaibins I-V: 15-Residue Peptaibols Produced by a Marine-Derived sp. of the Clade.

In the course of investigations on peptaibol chemodiversity from marine-derived spp., five new 15-residue peptaibols named pentadecaibins I-V (-) were isolated from the solid culture of the strain sp. MMS1255 belonging to the species complex. Phylogenetic analyses allowed precise positioning of the strain close to lineage inside the clade. Peptaibol sequences were elucidated on the basis of their MS/MS fragmentation and extensive 2D NMR experiments. Amino acid configurations were determined by Marfey's analyses. The pentadecaibins are based on the sequences Ac-Aib-Gly-Ala-Leu-Aib/Iva-Gln-Aib/Iva-Val/Leu-Aib-Ala-Aib-Aib-Aib-Gln-Pheol. Characteristic of the pentadecaibin sequences is the lack of the Aib-Pro motif commonly present in peptaibols produced by spp. Genome sequencing of sp. MMS1255 allowed the detection of a 15-module NRPS-encoding gene closely associated with pentadecaibin biosynthesis. Pentadecaibins were assessed for their potential antiproliferative and antimicrobial activities.