Vitamin carotenoids and

Most of the natural carotenoid pigments are tetraterpenes, being formed from two C20 geranylgeranyl pyrophosphate units through phytoene 4.122). The mechanism of phytoene formation has much in common with squalene biosynthesis. In particular, head-on fusion of the two C20 units occurs via prephytoene pyrophosphate 4.120), analogous to presqualene pyrophosphate 4.48) formation from two 

Most of the phytoene produced in vivo appears to be the 15,15 -aV isomer 4.122). Formation of 4.122) involves loss of the -pro-S)-proton from each of the two molecules of 4.105). In some bacteria the b, b -trans compound is produced by loss of the (l-/ ro-5)-proton from one molecule of 4.105) and the I-pro-R)-proton from the other [at the stage of 4.121)]. 

Desaturation of phytoene 4.122) occurs in a stepwise manner, each step extending the conjugation of the system, and leading finally to lycopene 4.123) (the desaturation sequence is then 

The most important carotenoid metabolites in animals are the vitamins A vitamin Aj (4.131), its 3,4-didehydro-derivative (vitamin A2), retinaldehyde (4.130) and its 3,4-didehydro-derivative. These vitamins are the basis of rhodopsin and other visual pigments. Retinaldehyde is formed by oxidative cleavage of jS-carotene via the peroxide (4.129) and the reaction is catalysed by an enzyme in the intestinal mucosa. 

A compound of unsuspected importance was isolated in 1885 from the fruit of Illicium religiosum. To this compound was given the name shikimic acid, a name derived from shikimi-no-ki which is the Japanese name for the plant. Shikimic acid (5.7), it transpired from the very elegant studies of much later investigators, is a key intermediate in the biosynthesis of the aromatic amino acids, L-phenylalanine, L-tyrosine and L-tryptophan, in plants and micro-organisms (animals cannot carry out de novo synthesis using this pathway). These three aromatic amino acids are individually important precursors for numerous secondary metabolites, and so to some extent are earlier biosynthetic intermediates related to shikimic acid, as the ensuing discussion in this chapter and in Chapters 6 and 7 will show. 

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Richard Kuhn chemistry work on carotenoids and vitamins... 

FAULKS R M, HART D J, SCOTT K J and SOUTHON s (1998) Changes in plasma carotenoid and vitamin E profile during supplementation with oil palm fruit carotenoids. J Lab Clin Med 132(6) 507-11. 

SCHMITZ H H, POOR c L, WELLMAN R B and ERDMAN J w Jr (1991) Concentrations of selected carotenoids and vitamin A in human liver, kidney and lung tissue. J Nutr 121(10) 1613-21. 

HIRSCHBERG J (1999) Production of high value compounds carotenoids and vitamin E , Curr Opin Biotech, 10, 186-91. 

Potischman, N. et al.. Breast cancer and dietary and plasma concentrations of carotenoids and vitamin A, Am. J. Clin. Nutr, 52, 909, 1990. 

Chen, B.H., Peng, H.Y., and Chen, H.E., Stability of carotenoids and vitamin A during storage of carrot juice. Food Chem., 57, 497, 1996. 

Injury (either physical or chemical) to the comeal endothelial cells has a marked efiect on occular function as these cells are responsible for maintaining the thickness and clarity of the cornea, yet they cannot be replaced if damaged. Immunohistochemical studies have revealed that enzymatic antioxidant defences, SOD, CAT and GSHPx, are similarly distributed in the corneal epithelium and endothelium (Rao etal., 1985 Attala et d., 1987, 1988). Other antioxidants include ascorbate, carotenoids and vitamin E (Fleath, 1962). 

Age-Related Eye Disease Study Research Group (2007), The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study, AREDS Report No. 22, Arch. Ophthalmol. 125 1225-1232. 

During, A, and Harrison, EH, 2007. Mechanisms of provitamin A (carotenoid) and vitamin A (retinol) transport into and out of intestinal Caco-2 cells. J Lipid Res 48, 2283-2294. 

Olmedilla B, Granado F, Southon S, Wright AJA, Blanco I, Gil-Martinez E, Berg H, Corridan B, Roussel AM, Chopra M and Thurnham DI. 2001. Serum concentrations of carotenoids and vitamins A, E, and C in control subjects from five European countries. British J Nutr 85(2) 227-238. 

Padula M and Rodriguez-Amaya DB. 1987. Changes in individual carotenoids and vitamin C on processing and storage of guava juice. Acta Aliment 16 209—216. 

Gil MI, Tomas-Barberan FA, Hess-Pierce B and Kader AA. 2002. Antioxidant capacities, phenolic compounds, carotenoids, and vitamin C contents of nectarine, peach, and plum cultivars from California. J Agric Food Chem 50(17) 4976-4982. 

Krukovsky, V. N., Whiting, F. and Loosli. J. K. 1950. Tocopherol carotenoid and vitamin A content of the milk fat and the resistance of milk to the development of oxidized flavors as influenced by breed and season. J. Dairy Sci. 33, 791-796. 

KARRER, PALL (1889-1971). A recipient of the Nobel print for chemistry in 1937 wfiih Walter N. Haworth. Although born in Moscow, he attended European universities and received his doctorate in Zurich. He Initiated work on Ituvins. carotenoids, and vitamins A and B. and accomplished work on structure and synthesis of vitamin Bi as well as vitamins A and E. 

Presents a table (Table 7) of chloropyll, carotenoid, and vitamin E levels (in pg/g dw) of green leaf tissue, vegetables, green and red fruits (tomato, red pepper), and nongreen plant foods (carrots, cauliflower). 

Serum total carotenoid and vitamin A concentrations fell by 30% in patients taking colestipol 30 g/day (2). 

Probstfield JL, Lin TL, Peters J, Hunninghake DB. Carotenoids and vitamin A the effect of hypocholesterole-mic agents on serum levels. Metabolism 1985 34(1) 88—91. 

De Flora, S., Bagnasco, M., and Vainio, H., Modulation of genotoxic and related effects by carotenoids and vitamin A in experimental models mechanistic issues, Mutagenesis, 14, 153-172, 1999. 

Georgiev, G.S. (1971). Carotenoids and vitamin A content in Salmo irideus eggs and their significance in the initial periods of the embryogenesis. Folia Balcanica 2(9), 11pp. 

ATBC 3d e Carotenoids and vitamin A 6.1 27,084 M Lower risk of lung cancer in the highest quintile of carotenoids same for highest quintile of consumption of fruit and vegetables reduction of cerebral infarction 139,140... 

A higher dosage of antioxidants or an increase of the intake of antioxidant with food was not modifying substantially the oxidative markers, despite a significant increase of a-tocopherol, carotenoids, and vitamin C in serum (92,93). 

NHSC 6 yr 83,234 F Gonsumption of fruit and vegetables high in carotenoids and vitamins may reduce postmenopausal breast cancer (192)... 

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