SOME NATURAL AND SYNTHETIC ANTIOXIDANTS AS STABILIZERS OF BETA-CAROTENE CONVERSION INTO VITAMIN-A

The effect of antioxidants (vitamins C and E, quercetin, probucol, but ylated hydroxytoluene) on the oxidation of beta-carotene and its conve rsion into retinal under the influence of beta-carotene 15,15'-dioxyge nase (CDO) from rat intestinal mucosa was studied. The activity of CDO decreased in the presence of oxidants. Antioxidants protected both th e substrate and the enzyme. The extent of the protection depended on t he antioxidant type. The combined injection of antioxidants and beta-c arotene to animals completely or partially prevented the inhibition of the intestinal CDO which was caused by products of non-enzymatic oxid ation of beta-carotene. vitamins C and E, which protected the enzyme-s ubstrate complex in vivo and in vitro, were found to be the most effic ient protectors of beta-carotene conversion into retinal.