Natural polyketide 6-pentyl-2H-pyrone-2-one and its synthetic analogues efficiently prevent marine biofouling

Biofouling is a widespread phenomenon in oceans worldwide. With increasing human development and activities in open and coastal waters, and due to the environmental impact of AF organotins and copper-based paint, the demand for nontoxic antifouling (AF) paints is increasing. Various bioassays for antimicrobial activity, anti-biofilm formation and anti-barnacle settlement were established to evaluate the possibility of using marine natural products as AF agents. A series of natural products, isolated from the marine-derived fungi Trichoderma atroviride and T. reesei, were evaluated for their AF activity. One pyrone-type compound (1) demonstrated significant inhibitory activities toward barnacle cyprid settlement. Furthermore, a series of pyrone analogues (S1-S6) were synthesized, and their bioactivities were evaluated in the established systems. The results showed that compounds S5 and S6 exhibited a broad spectrum of bioactivities, such as anti-barnacle settlement, anti-biofilm formation and antimicrobial activities.