Studies in vitamin A. 19. Preparation and properties of retinene2

Publisher Website
Google Scholar
Abstract
The liver of ling cod (Ophiodon elongatus) contains vit. A1 and vit. A2 in the ratio 1/8-1/10. The partially sterol-free unsaponifiable fraction in light petroleum left to stand over MnO2 gives a mixture of retinene1 and retinene2. Separation can be effected by chromatography on water alumina. The liver oil of pike (Esox lucius). though not a very rich source of vit. A, contains more A2 than A1 and the unsaponifiable fraction after oxidation contains the 2 retinenes, which can be separated. Liver oil obtained from mixed large freshwater fishes of Lake Nyasa contains up to 15% of mixed vits. A (A2/A1 about 1/3). The sterol-free unsaponifiable fraction yields mixed retinenes on oxidation by MnO2- One prepn. of retinene2 showed m.p.61[degree] (not raised by recrystallization) but numerous subsequent prepns. melted sharply at 77-78[degree]. Retinene2 is an aldehyde forming a 2,4-dinitrophenylhydrazone and semicarbazone. The absorption curves in several solvents were recorded. The SbCl3 color test is greenish blue, [lambda] max. 740 m[mu] initially, fading to 705 m[mu]. Retinene2 as obtained above agrees in its properties with the material obtained from bleached freshwater-fish retinas.
Keywords