Enzymatic Hydrolysis of Ascorbate-2-monophosphate and Ascorbate-2-sulphate in Vitro, and Bioactivity of Ascorbate-2- Monophosphate in Atlantic Salmon (salmo Salar)

An in uitro study indicated that the phosphate moiety of Ca ascorbate-2-monophosphate (AP) is enzymatically hydrolyzed to ascorbic acid and phosphate in the gastrointestinal tract of Atlantic salmon (Salmo salar). A Seeding experiment demonstrated significant vitamin C bioactivity of AP in this species, and by comparing the results with other studies it is suggested that the bioactivity of AP is equivalent to ascorbic acid (AA). The reported low vitamin C bioactivity of ascorbate-2-sulphate (AS) may probably be explained by lack of sulphatase activity in the gastrointestinal tract of the fish. It is suggested that fish have selective absorption mechanisms for AA, and that the derivatives tested are only absorbed after they have been hydrolysed in the intestine.