Structure-Functional Activity of Pyrone Derivatives for Inhibition of Barnacle Settlement and Biofilm Formation

Naturally occurring 6-pentyl-2H-pyran-2-one and its synthetic analogues greatly inhibit the settlement of Amphibalanus amphitrite cyprids and the growth and biofilm formation of marine bacteria. To optimize the antifouling activities of pyrone derivatives, this study designed pyrone analogues by modifying functional groups, such as the benzyl group, cyclopentane, and halides, substituted on both sides of a pyrone. The antifouling effects of the synthesized pyrone derivatives were subsequently evaluated against five marine biofilm–forming bacteria, Loktanella hongkongensis, Staphylococcus cohnii, S. saprophyticus, Photobacterium angustum, and Alteromonas macleodii, along with barnacle cyprids of Amphibalanus amphitrite. Substituting nonpolar parts—such as the aliphatic, cyclopentyl, or phenyl moieties on C-5 or the furan moieties on C-3—not only increased antibacterial activity and inhibited biofilm formation but also inhibited barnacle cyprid settlement when compared to 6-pentyl-2H-pyran-2-one.