Toward Sustainable Antifouling Solutions: Degradation Profile of Promising Nature-Inspired Flavonoids

The accumulation of aquatic organisms on submerged surfaces causes major economic and environmental impacts in marine ecosystems. Conventional antifouling biocides pose risks due to toxicity to non-target species and bioaccumulation. Nature-inspired compounds such as flavonoids have emerged as more sustainable alternatives. Aiming to assess the environmental impact of new antifouling flavonoids and to evaluate the toxicity of their transformation products, this study investigates the degradation of three promising antifouling flavonoids (chalcone CC345G and dihydrochalcones DH345 and DH345P) in aqueous matrices. Comprehensive abiotic and biotic degradation assays (hydrolysis, photodegradation, and biodegradation) were conducted. Appropriate liquid chromatography with UV detection methods were developed and validated to monitor the studies. The glycosylated chalcones bearing a triazole moiety CC345G revealed no detectable degradation under any of the experimental conditions. In contrast, both dihydrochalcones underwent significant abiotic degradation; DH345 was more susceptible to hydrolysis at pH 7.10 (17.41% degradation), while DH345P was more prone to photolysis in sterilized natural seawater at pH 8.82 (45.82–54.52% degradation), also showing substantial degradation in hydrolysis (24.34–42.41%) and biodegradation (33.43–41.07%). Overall, the prenylated dihydrochalcone DH345P exhibited the highest degradation rate among the tested compounds. Analysis with high-resolution mass spectrometry disclosed several transformation products in degradation assays, and one chemical structure was proposed. Preliminary ecotoxicity assessment performed on the degradation products using Artemia salina indicated low toxicity, suggesting minimal environmental impact.