首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
4.
5.
The inhibitory effects of vitamins A and K toward P4501A1-dependent 7-ethoxycoumarin O-deethylation were examined in the reconstituted system containing the microsomal fraction prepared from the recombinant Saccharomyces cerevisiae cells producing rat P4501A1 and yeast NADPH-P450 reductase. On vitamins A, all-trans-retinol, all-trans-retinal, all-trans-retinoic acid and retinol-palmitate showed competitive inhibition with K(i) values of 0.068, 0.079, 2.6 and 2.0 microM, respectively. Judging from the K(i) values, the inhibitory effects of those vitamins A appear to have physiological significance on the basis of their contents in liver, lung and kidney. On vitamins K, vitamin K(1) showed competitive inhibition with K(i) value of 24 microM, while vitamin K(2) showed noncompetitive inhibition with K(i) value of 60 microM. Judging from these K(i) values together with the contents of these vitamins K in liver, the inhibitory effects of the vitamins K are not as significant as those of vitamins A. These results suggest that the ingestion of enough amounts of vitamins A from foods might lead to the inhibition of the activity of P4501A1 which is known to be induced by smoking, drugs such as omeprazole and lansoprazole, and environmental pollutants like dioxins.  相似文献   

6.
7.
8.
Twenty primiparous dairy sheep of the Mytilene breed, which were fed with a ration deficient in vitamin A and carotenes, were divided into 2 groups of 10 animals each after a 2-month adaptation period. The animals of group A were administered vitamin A palmitate by intramuscular injection (3500 IU/kg bodyweight), while the animals of group B were used as controls and received only the vehicle of the preparation without vitamin A. Serum vitamin A concentrations increased significantly in the animals of group A compared to the animals of group B (P < 0.01) from the first 24 h post-injection and remained significantly high for 8 days, and at 10 days post-injection they reached the pre-injection levels. The serum vitamin E concentration declined significantly (P < 0.05) in the animals of group A compared to the animals of group B for 8 days, when they reached the pre-injection levels. No changes in serum vitamins A and E levels in the animals of the 2 groups were observed 20 days after the injection of vitamin A.  相似文献   

9.
Spermatogenic response to vitamin A in vitamin A deficient rats   总被引:4,自引:0,他引:4  
  相似文献   

10.
11.
12.
13.
Vitamin D metabolites and analogs induce de novo synthesis of a specific calcium-binding protein in embryonic chick duodenum maintained in organ culture. Using calcium-binding protein biosynthesis as a specific and sensitive biochemical indicator of intrinsic biopotency, 24,24-difluoro-1α,25-dihydroxy vitamin D3 was found to be approximately four times more potent on a molar basis than the most active, naturally occurring metabolite, 1α,25-dihydroxy vitamin D3.  相似文献   

14.
Vitamin A antibodies were obtained using retinoic acid conjugated to human serum albumin as an immunogen. The following constraints governed the reactivity of vitamin A analogues with such an anti-serum. The stereochemistry of the side chain is relatively unimportant, and 9- and 13-cis retinal react almost as well as all-trans retinal. The nature of the ring is important; all of the compounds that react readily carry a beta-ionic ring; all of the compounds bearing an aromatic ring react poorly; the two compounds that display intermediate reactivity have non-aromatic 6- and 5-membered rings, respectively.  相似文献   

15.
16.
17.
18.
The primary objective of this review is to propose an approach for the biosynthesis of phylloquinone (vitamin K1) based upon its known sources, its role in photosynthesis and its biosynthetic pathway. The chemistry, health benefits, market, and industrial production of vitamin K are also summarized. Vitamin K compounds (K vitamers) are required for the normal function of at least 15 proteins involved in diverse physiological processes such as coagulation, tissue mineralization, inflammation, and neuroprotection. Vitamin K is essential for the prevention of Vitamin K Deficiency Bleeding (VKDB), especially in neonates. Increased vitamin K intake may also reduce the severity and/or risk of bone fracture, arterial calcification, inflammatory diseases, and cognitive decline. Consumers are increasingly favoring natural food and therapeutic products. However, the bulk of vitamin K products employed for both human and animal use are chemically synthesized. Biosynthesis of the menaquinones (vitamin K2) has been extensively researched. However, published research on the biotechnological production of phylloquinone is restricted to a handful of available articles and patents. We have found that microalgae are more suitable than plant cell cultures for the biosynthesis of phylloquinone. Many algae are richer in vitamin K1 than terrestrial plants, and algal cells are easier to manipulate. Vitamin K1 can be efficiently recovered from the biomass using supercritical carbon dioxide extraction.  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号