New colorimetric method for the estimation of aldehyde derivatives of vitamin A

✍ Scribed by A. Krishna Mallia; H.R. Cama

• Publisher: Elsevier Science
• Year: 1969
• Tongue: English
• Weight: 216 KB
• Volume: 30
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(69)90375-3

✦ Synopsis

Futterman and Saslaw (1) have described a method for the estimation of retinal in the presence of retinyl acetate, retinol, retinoic acid, or p-carotene. The method depends upon formation of a colored derivative of retinal by reaction with thiobarbituric acid. This method has been successfully employed for the estimation of 3-dehydroretinal, 5,6-monoepoxyretinal and 5,6-monoepoxy-3-dehydroretinal

(2-4). In the present paper, a new calorimetric method for the estimation of retinal, 3-dehydroretinal, 5,6-monoepoxyretinal and 5,6-monoepoxy-3dehydroretinal is described. The assay depends upon the formation of colored derivatives of the vitamin A aldehydes by reaction with p-aminobenzoic acid or p-aminosalicylic acid in the presence of hydrochloric acid.

Methods

Retinal was prepared by the oxidation of retinol with manganese dioxide according to the procedure of Ball et al. ( 5). 3-Dehydroretinal was prepared from the Indian freshwater fish liver oil Wallago attu (6, 7). 5,bMonoepoxyretinal was obtained as described by Jungalwala and Cama (8). 5,6-Monoepoxy-3-dehydroretinal was prepared as described earlier (4). p-Aminobenzoic a&d or p-aminosalicylic acid reagent: 2.0 gm of p-aminobenzoic acid or 2.0 gm of p-aminosalicylic acid was dissolved in 200 ml of ethanol. The reagent could be stored indefinitely at room temperature.

Stock sdutions of retinal, S-dehydroretinal, 6,&monoepoxyretinal, and b,6-monoepoxy-S-dehydroretinal: 10.0 mg each of retinal, 3-dehydroretinal, 5,6-monoepoxyretinal, and 5,6-monoepoxy-3-dehydroretinal were dissolved, separately, in 100 ml of ethanol and the solutions were stored at -30".