Synthesis and fouling resistance of capsaicin derivatives containing amide groups

Natural capsaicin extracted from pungent plants can impede marine organisms and achieve antifouling effects, and it will not kill marine fouling organisms. Its derivatives inherit the good antifouling effects and toxicity. When it is introduced into an antifouling system, capsaicin can meet the environmental requirements of antifouling coatings. Using N-hydroxymethyl phthalimide and aromatic compounds as raw materials, six new active structural derivatives containing capsaicin were synthesized by the Friedel craft alkylation reaction, and their structures were determined by IR, NMR and MS. The antibacterial and algal inhibitory properties of the compound were tested, and the results revealed it had certain inhibitory effects on Marine bacteria and algae, with strong antibacterial and algal inhibitory properties observed of products D, E and F. The minimum inhibitory concentration was 0.1875 mg/mL, and the highest antibacterial rate of 3 mg/mL was 93.05%. The highest algae inhibition rate on the seventh day was 88.34%, the toxicity was low, and the toxicity grade was low. The compound as an antifouling agent added to marine antifouling coatings shows a good antifouling effect, thus laying a good foundation for research on environmentally friendly antifouling coatings.