Antifouling properties of simple indole and purine alkaloids from the Mediterranean gorgonian Paramuricea clavata

Abstract

Chemical investigation of the Mediterranean gorgonian Paramuricea clavata resulted in the isolation of two new alkaloids, 2-bromo-N-methyltryptamine (1) and 3-bromo-N-methyltyramine (2), together with nine known compounds (3-10 and linderazulene). The bromoindole derivative 3 is reported herein for the first time from a natural source. The chemical structures of these compounds were assigned by spectroscopic analyses and comparison with literature values. The antifouling activity and toxicity of compounds 1-10 were assessed using three marine biofilm bacteria and the Microtox assay. In contrast to commercial antifoulants, bufotenine (5) and 1,3,7-trimethylisoguanine (10) showed significant antiadhesion activity against one bacterial strain while being nontoxic.