Evaluation of photodegradable chitin synthetase inhibitors for the treatment of salmon lice (Lepeophtheirus salmonis)

Some photolabile ethanolamine analogues of the chitin synthetase inhibitors diflubenzuron, teflubenzuron, and lufenuron were tested for activity as anti-lice compounds towards salmon lice (Lepeophtheirus salmonis). Two teflubenzuron analogues (2 and 3) exhibited interesting biological activity whereas their corresponding photodecomposition products were inactive. One of the analogues (3) decomposes completely when irradiated at pH 8, a relevant pH for seawater. In comparison, diflubenzuron showed a 66% photodecomposition under identical conditions. Thus, ethanolamine 3 is an interesting lead compound in the search for a powerful, environmentally friendly chemical to use in salmon-lice treatment. •New chitin synthetase inhibitor for the treatment of salmon lice•The new chitin synthetase inhibitor photodegrades•The new chitin synthetase inhibitor has a shorter half-life in the environment than chitin synthetase inhibitors currently in use