Intestinal beta-carotene 15,15'-dioxygenase activity is markedly enhanced in copper-deficient rats fed on high-iron diets and fructose.
The purpose of the present work was to examine effects of the Cu-Fe interaction on intestinal beta-carotene 15,15'-dioxygenase activity when a wide range of dietary Fe (deficiency to excess) was used in relation to Cu status of rats. The effect of dietary carbohydrates was also examined since they play a role in the Cu-Fe interaction in vivo. Weanling male Sprague-Dawley rats (n 72) were divided into twelve dietary groups, which were fed on either low-, normal-, or high-Fe levels (0.9, 9.0, and 90.0 mmol Fe/kg diet respectively) combined with Cu-adequate or -deficient levels (0.94 and 0.09 mmol Cu/kg diet respectively) and with starch or fructose in the diets. The data showed that both Fe concentration and beta-carotene 15,15'-dioxygenase activity in small intestinal mucosa were enhanced with increasing dietary Fe and with Cu deficiency v. Cu adequacy. Dietary fructose did not aggravate the Fe-enhancement, related to Cu deficiency, in the small intestine; however, fructose increased the intestinal dioxygenase activity in rats fed on normal- or high-Fe diets when compared with starch controls. Thus, the highest intestinal dioxygenase activity associated with the lowest hepatic retinol (total) concentration was found in rats fed on the Cu-deficient, high-Fe, fructose-based diet. Finally, a positive linear relationship was found between the dioxygenase activity and Fe concentration in intestinal mucosa. In conclusion, the data indicate that beta-carotene 15,15'-dioxygenase activity requires Fe as cofactor in vivo and the enzyme is modulated by the three dietary components: Cu, Fe, and fructose.
During
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Phytonutrients Laboratory, USDA-ARS, Beltsville Human Nutrition Research Center, Maryland 20705, USA. during@bhnrc.arsusda.gov
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Lewis
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Smith
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D000704:Analysis of Variance; D000818:Animals; D003300:Copper / Q000008:administration & dosage / Q000172:deficiency; D005632:Fructose / Q000008:administration & dosage; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism; D007421:Intestine, Small / Q000201:enzymology / Q000378:metabolism*; D007501:Iron / Q000008:administration & dosage; D000090463:Iron Deficiencies; D008297:Male; D009752:Nutritional Status; D010105:Oxygenases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013213:Starch / Q000008:administration & dosage; D019207:beta Carotene / Q000378:metabolism*; D050559:beta-Carotene 15,15'-Monooxygenase
C493357:Bco1 protein, rat; D019207:beta Carotene; D005632:Fructose; D003300:Copper; D013213:Starch; D007501:Iron; D010105:Oxygenases; D050559:beta-Carotene 15,15'-Monooxygenase