Metabolism of cryptoxanthin in freshwater fish

Abstract

1. In search of other provitamins A, the metabolism of cryptoxanthin was studied in several species of freshwater fish, i.e. Chunna gachua, Labeo boga (retinol-rich) and Heteropneustes fossilis (dehydroretinol-rich). The fish were either allowed to starve for 20–25 d to make their intestines free from carotenoids and vitamin A or kept on a vitamin-A-deficient diet for 140–150 d to deplete the initial reserve of vitamin A in the livers.2. Retinol-rich freshwater fish such as C. gachua and L. boga converted cryptoxanthin into retinol and no 3-dehydroretinol or 3-hydroxyretinol could be isolated from those fish that received cryptoxanthin.3. 3-Hydroxyretinol and 3-dehydroretinol were isolated from the vitamin-A-deficient H. fossilis, a 3-dehydro-retinol-rich freshwater siluroid, after the administration of cryptoxanthin.