Preparation and evaluation of polyphenol derivatives as potent antifouling agents: addition of a side chain affects the biological activity of polyphenols

In this study, eight polyphenol derivatives were prepared to serve as green antifoulants. Polyphenol derivatives, which can hinder the growth of bacteria and algae and decrease the adhesion of some marine organisms, showed good AF activity; in particular, the activities of these derivatives were much higher than those of the corresponding polyphenols. The antibacterial rates of the products (20 μg ml−1) exceeded 88%. Moreover, the anti-algal rates of compounds a3, b1, b2, b3 and b4 (15 μg ml−1) were over 57% at 240 h, but these compounds showed low toxicity, and the 120 h EC50 values were > 6.60 μg ml−1. In addition, there were fewer marine microorganisms on the test panel than on the control. The above results show that some polyphenol derivatives possess relatively high antibacterial, anti-algal, and AF activity; more notably, the addition of chlorine atoms and amide groups can further increase the activity of these derivatives.