Vitamins Xanthine

Alkenes with many double bonds in a row are colored. Some plant pigments are alkenes of this kind. One example is )S-carotene, which gives carrots their distinctive orange color. Animals break down )S-carotene into vitamin A, which is essential for vision. Xanthin molecules, relatives of j6-carotene that contain oxygen atoms, occur in com, orange juice, and shellfish. The xanthin below makes the flamingo pink. 

The lag-phase measurement at 234 nm of the development of conjugated dienes on copper-stimulated LDL oxidation is used to define the oxidation resistance of different LDL samples (Esterbauer et al., 1992). During the lag phase, the antioxidants in LDL (vitamin E, carotenoids, ubiquinol-10) are consumed in a distinct sequence with a-tocopherol as the first followed by 7-tocopherol, thereafter the carotenoids cryptoxanthin, lycopene and finally /3-carotene. a-Tocopherol is the most prominent antioxidant of LDL (6.4 1.8 mol/mol LDL), whereas the concentration of the others 7-tocopherol, /3-carotene, lycopene, cryptoxanthin, zea-xanthin, lutein and phytofluene is only 1/10 to 1/300 of a-tocopherol. Since the tocopherols reside in the outer layer of the LDL molecule, protecting the monolayer of phospholipids and the carotenoids are in the inner core protecting the cholesterylesters, and the progression of oxidation is likely to occur from the aqueous interface inwards, it seems reasonable to assign to a-tocopherol the rank of the front-line antioxidant. In vivo, the LDL will also interact with the plasma water-soluble antioxidants in the circulation, not in the artery wall, as mentioned above. 

Sleet, R.B. and J.H. Soares, Jr. 1979. Some effects of Vitamin E deficiency on hepatic xanthine dehydrogenase activity, lead, and a-tocopherol concentrations in tissues of lead-dosed mallard ducks. Toxicol. Appl. Pharmacol. 47 71-78. 

The yellow color of the AM 13,1 colonies is due to their content of compound 26. In most other cases, yellow cultures owe their color to the carotenoid zea-xanthin (Hel21) or one of the many vitamin K derivatives (e.g., menaquinone MK6 in Hel21). 

The distribution of trace elements among the compounds and physical phases in milk has not been elucidated completely. Molybdenum appears to be found exclusively in xanthine oxidase and Co in vitamin B12. Iron is an essential component of xanthine oxidase, lactoperoxi-dase, and catalase. About half of the total Fe and 10% of the Cu are in the fat globule membrane. Copper has been studied extensively in relation to oxidation of milk lipids. The trace metal present in highest con-... 

Ascorbic Acid (AA). Experimental (SI, S7, S24) and clinical (B13, B17) studies have provided some evidence for the concept that oxidative stress is the common pathway for the initiation of AP (B14). The most abundant endogenous antioxidant in the aqueous phase is ascorbic acid (AA), a bioactive form of vitamin C, which scavenges oxygen-derived free radicals produced by activated neutrophils and the hypoxanthine-xanthine oxidase system (D12). Scott et al. 

The U.S./Canadian Dietary Reference Values report (Institute of Medicine, 2001) introduced the term retinol activity equivalent to take account of the incomplete absorption and metabolism of carotenoids 1 RAE = 1 /xg of all-fra s-retinol, 12 /xg of /3-carotene, and 24 /xg of a-carotene or /3-crypto-xanthin. On this basis, 1 iu of vitamin A activity = 3.6 /xg of /3-carotene or... 

Tranquillisers hQn Qx do, captodiame, clopenthixol, flupen-thixol, haloperidol, phenothiazines, prothipendyl, trifluperidol Vitamins acetomenaphthone, ascorbic acid, ergocalciferol, nicotinamide, pyridoxine, riboflavine, thiamine Xanthines acepifylline, bamifylline, bufylline, caffeine, dipro-phylline, etamiphylline, theobromine, theophylline Miscellaneous substances aminosalicylic acid, benzoic acid, betanaphthol, carbamazepine, chlorphenesin, dibromoprop-amidine, diethylpropion, halquinol, isoniazid, methaqualone, metronidazole... 

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