Anti‐Barnacle Activities of Isothiocyanates Derived from β‐Citronellol and Their Structure–Activity Relationships

Abstract

Antifouling agents with low toxicity are in high demand for sustaining marine industries and the environment. This study aimed to synthesize 15 isothiocyanates derived from β‐citronellol and evaluate their antifouling activities and toxicities against cypris larvae of the barnacle Amphibalanus amphitrite. The synthesized isothiocyanates exhibited effective antifouling activities (EC50=0.10–3.33 μg mL−1) with high therapeutic ratios (LC50/EC50 >30). Four isothiocyanates with an amide or isocyano group showed great potential as effective antifouling agents (EC50=0.10–0.32 μg mL−1, LC50/EC50=104–833). The enantiomers of the isothiocyanates only slightly differed in their antifouling activities. These results may serve as a basis for further research and development of β‐citronellol‐derived isothiocyanates as effective low‐toxic antifouling agents. To the best of our knowledge, this study is the first to report the antifouling activities of isothiocyanates derived from accessible natural products.

Research Progress of Natural Products and Their Derivatives in Marine Antifouling

“…Isothiocyanate compounds isolated from some vegetables have been considered as promising low-toxic AF agents. Yoshikazu Kitano’s group synthesized fifteen β-citronellol-derived isothiocyanate compounds and analyzed their structure–activity relationships [ 46 ]. All the synthesized isothiocyanate compounds exhibited effective AF activities, with high therapeutic ratios (LC 50 /EC 50 > 30).…”

“…Based on these latest research results, it can be seen that the AF properties of the compounds are affected by molecular structures. For example, isothiocyanates with different enantiomers (such as isocyano groups, acetamide groups, amide groups and halogen) exhibited different AF activities [ 46 ]. The number of hydrophobic biphenyl groups and hydrophilic cationic arginine sidechains affected the lipophilicity of DKPs.…”