Effect of d,l-alpha-tocopheryl esters on vitamin E-deficient rats.
The data in our previous paper demonstrated that some alpha-tocopheryl esters administered orally were absorbed in their unchanged form through the lymph, while some other esters were absorbed after being hydrolyzed individually to different degrees. The hydrolysis during absorption seems to be related to the structure of the ester group of alpha-tocopherol at the 6-position. The purpose of this work is to study the metabolism and biological effect of tocopherol esters in vitamin E-deficient rats. Three esters were used on the basis of their behavior during absorption through the lymph, as follows; alpha-tocopheryl acetate (an easily hydrolyzable ester), the nicotinate (a moderately hydrolyzable one) and the pivalate (a scarcely hydrolyzable one). The easily hydrolyzable esters will suffer the same metabolic fate through absorption as alpha-tocopherol. The moderately and scarcely hydrolyzable ones have a tendency to show different physiological effects from alpha-tocopherol due to absorption of the unchanged ester. The effect of these esters on the microsomal enzymes in the liver such as cytochrome P-450, cytochrome b5, aniline and hexobarbital difference spectra and NADPH-dependent cytochrome c reductase was determined. It was shown that the pivalate inhibited the release of NADPH-dependent cytochrome c reductase activity to supernatant in spite of low distribution in the 105,000 X g sediment. The result suggests that the pivalate as a model compound may be interesting to examine for its membrane stabilizing effect of alpha-tocopherol.
D000085:Acetates / Q000378:metabolism; D000818:Animals; D006461:Hemolysis / Q000187:drug effects; D006868:Hydrolysis; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008862:Microsomes, Liver / Q000201:enzymology; D009539:Nicotinic Acids / Q000378:metabolism; D011422:Propionates / Q000378:metabolism; D051381:Rats; D013329:Structure-Activity Relationship; D014018:Tissue Distribution; D014810:Vitamin E / Q000378:metabolism* / Q000494:pharmacology; D014811:Vitamin E Deficiency / Q000378:metabolism*
D000085:Acetates; D009539:Nicotinic Acids; D011422:Propionates; D014810:Vitamin E