科研之友
微信
新浪微博
Facebook
分享链接
摘要
Dietary alpha-carotene is present in oranges and purple-orange carrots. Upon the central cleavage of alpha-carotene in the intestine, alpha-retinal and retinal are formed and reduced to alpha-retinol (alpha R) and retinol. Previous reports have suggested that alpha R has 2% biopotency of all-trans-retinyl acetate due in part to its inability to bind to the retinol-binding protein. In the present work, we carried out three studies. Study 1 re-determined alpha R's biopotency compared with retinol and 3,4-didehydroretinol in a growth assay. Weanling rats (n 40) were fed a vitamin A-deficient diet for 8 weeks, divided into four treatment groups (n 10/group) and orally dosed with 50nmol/d retinyl acetate (14 center dot 3 mu g retinol), alpha-retinyl acetate (143 mu g alpha R), 3,4-didehydroretinyl acetate (14 center dot 2 mu g DR) or cottonseed oil (negative control). Supplementation was continued until the control rats exhibited deficiency signs 5 weeks after the start of supplementation. Body weights and AUC values for growth response revealed that alpha R and DR had 40-50 and 120-130% bioactivity, respectively, compared with retinol. In study 2, the influence of alpha R on liver ROH storage was investigated. The rats (n 40) received 70nmol retinyl acetate and 0, 17 center dot 5, 35 or 70nmol alpha-retinyl acetate daily for 3 weeks. Although liver retinol concentrations differed among the groups, alpha R did not appreciably interfere with retinol storage. In study 3, the accumulation and disappearance of alpha R over time and potential liver pathology were determined. The rats (n 15) were fed 3 center dot 5 mu mol/d alpha-retinyl acetate for 21d and the groups were killed at 1-, 2- and 3-week intervals. No liver toxicity was observed. In conclusion, alpha R and didehydroretinol are more biopotent than previously reported at sustained equimolar dosing of 50nmol/d, which is an amount of retinol known to keep rats in vitamin A balance.
- 出版日期2014-4-28
