1. The vitamin A content of Saccobranchus fossilis kept on a diet of rice and meat gradually decreased and became negligible at the end of 3–5 months.2. S. fossilis initially contained more dehydroretinol than retinol; administration of β-carotene or zeaxanthin to the vitamin A-depleted fish did not result in an accumulation of dehydroretinol in the liver. On the other hand, when lutein was administered by mouth or subcutaneous injection, it was converted into dehydroretinol.

The intestines of freshly caught Saccobranchus fossilis (a freshwater fish that contains dehydroretinol) became free from carotenoids and from vitamin A when the fish were starved for about 20 days. When beta-carotene was administered to such fish, retinoic acid could be isolated from the intestines after approx. 4h. When lutein was administered to such fish, dehydroretinol and 3-hydroxyretinol could be isolated from the intestines after approx. 5h.

1. Lutein and anhydrolutein have been isolated from liver oils of freshly caught Sacco-branchus fossilis.2. S. fossilis initially contained more dehydroretinol than retinol; administration of anhydrolutein to the vitamin A-depleted fish resulted in the accumulation of dehydroretinol.3. Anhydrolutein has also been isolated from the liver oils of lutein-treated, vitamin A-depleted fish.4. The pathway of the conversion of lutein into dehydroretinol is discussed.

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1. Anthers of Delonix regia flowers are a rich source of zeaxanthin. 2. Oxidation of zeaxanthin with hydrogen peroxide in the presence of osmium tetroxide results in the formation of 3-hydroxyretinene as one of the products. 3. 3-Hydroxyretinene gives 3-acetoxyretinene with acetic anhydride, and an oxime with hydroxylamine hydrochloride. 4. Reduction of 3-hydroxyretinene with sodium borohydride yields 3-hydroxyvitamin A. 5. Treatment of 3-hydroxyvitamin A with dry ethanolic hydrogen chloride results in the formation of 3-ethoxyanhydrovitamin A (anhydrovitamin A(2)) and a compound that resembles naturally occurring anhydrovitamin A(2).