
A joint collaborative effort coordinated by Prof Jörn Piel from the ETH Zürich (Switzerland) led to the identification of new antibiotic compounds from Aquimarina sp. strain Aq135 which was cultivated from the marine sponge Ircinia variabilis in the laboratory of Prof Rodrigo Costa from BSRG-iBB. Activity-guided isolation identified novel antibacterial peptides, named aquimarins, featuring a new scaffold with an unusual C-terminal amino group and chlorine moieties. Structure–activity relationship studies with these compounds showed that the synthetically more laborious chlorinations are not required for antibacterial activity but enhance cytotoxicity. In contrast, variants lacking the C-terminal amine were virtually inactive, suggesting diamines similar to the terminal aquimarin residue as candidate building blocks for new peptidomimetic antibiotics. The study was published in Angewandte Chemie.