Determination of Selenoneine in Seafood and Seafood-Derived Products

Abstract Background Selenoneine exhibits antioxidant properties and is thus expected to become a new functional ingredient. Accurately determining selenoneine levels in foods is therefore critical. Objective This study investigated and validated extraction methods for selenoneine in seafood and seafood-derived products. Methods Selenoneine was extracted from seafood and seafood-derived products by sonication for 1 h and incubation at 37 °C for 24 h in a solution of 50 mmol/L dithiothreitol (DTT). The concentration of selenoneine was then determined using liquid chromatography–inductively coupled plasma mass spectrometry (LC–ICP-MS) and size-exclusion column chromatography using a mobile phase of 0.1 mmol/L ammonium acetate with 0.1% IGEPAL®. Results The method was validated using a DTT solution that effectively extracts selenoneine. The LOD (0.020–0.030 mg/kg), LOQ (0.067–0.099 mg/kg), repeatability (3.4–8.9%), intermediate precision (4.1–8.9%), and trueness (recovery of 94–109% based on spiked samples) of the proposed method were satisfactory for determining selenoneine in seafood and seafood-derived products. Selenoneine was detected in migratory fish and processed migratory fish products obtained in Japan. Particularly large amounts of selenoneine were detected in the dark muscle of bluefin tuna. Conclusion Using a reagent reactive to thiol groups, selenoneine was effectively extracted from seafood and seafood-derived products. The results of method validation analyses were satisfactory. Selenoneine was detected in processed products prepared from migratory fish, indicating that selenoneine remains even after processing. Water-soluble selenoneine was found to be extracted in the liquid. Highlights Selenoneine could be effectively extracted using DTT, and determination of selenoneine in various seafood was possible using LC–ICP-MS.