Ascorbic acid biosynthesis

L-Ascorbic acid biosynthesis in plants and animals as well as the chemical synthesis starts from D-glucose. The vitamin and its main derivatives, sodium ascorbate, calcium ascorbate, and ascorbyl palmitate, are officially recognized by regulatory agencies and included in compendia such as the United S fates Pharmacopeia/National Formula (USP/NF) and the Food Chemicals Codex (FCC). 

In all plants and most animals, L-ascorbic acid is produced from D-glucose (4) and D-galactose (26). Ascorbic acid biosynthesis in animals starts with D-glucose (4). In plants, where the biosynthesis is more compHcated, there are two postulated biosynthetic pathways for the conversion of D-glucose or D-galactose to ascorbic acid. 

Glucosyl-fructose, 24 237 D-Glucuronic acid, 4 711 Glucuronic pathway, of ascorbic acid biosynthesis, 25 762-763, 763-764 Glue, kaolin application, 6 688t Glueckauf approximation, adsorption, 1 608, 609... 

N. Smirnoff, L-Ascorbic acid biosynthesis, Vitam. Horm., 61 (2001) 241-266. 

Baig, M.M., Kelly, S., and Loewus, F., 1970, l-Ascorbic acid biosynthesis in higher plants from L-gulono- or L-galactono-1,4-lactone. Plant Physiol. 46 277-280. 

Jain, A.K., and Nessler, C.L., 2000. Metabolic engineering of an alternative pathway for ascorbic acid biosynthesis in plants. Mol. Breeding 6 73-78. 

Nishikimi, M., Fukuyama, R., Minoshima, S., Shimizu, N., and Yagi, K., 1994, Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-gamma-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man. J. Biol. Chem. 269 13685-13688. 

The functions and fate of i.-ascorbic acid in humans and other primates are reviewed in this chapter. Topics included are use of subhuman primates for research in nutrition evolution and subsequent loss of ascorbic acid biosynthesis absorption, tissue transport, and distribution of ascorbic acid and catabolism, functions, and requirements of ascorbic acid. In retrospect, the insight provided by this chapter suggests new work areas of emphasis for developing better understanding of the vitamins role in human health. 

Evolution and Subsequent Loss of Ascorbic Acid Biosynthesis... 

Conney AH, Bums JJ. 1959. Stimulatory effect of foreign compounds on ascorbic acid biosynthesis and on drug-metabolizing enzymes. Nature 184 363-64... 

L-Gulonolactone Figure 8.57. Outline of ascorbic acid biosynthesis. 

Figure 7.9 Ascorbic acid biosynthesis and action as a reductant.

The new knowledge of ascorbic acid biosynthesis and degradation has called attention to the variable metabolism of ascorbic acid, induced by drugs of various kinds, and to the complementary effects on the metabolism of drugs, produced by ascorbic acid. Changes of this sort may eventually explain many puzzling features of the metabolism of ascorbic acid in scorbutic animals in different physiological states. 

Roy and Guha (R24) induced experimental scurvy in a bird, the red-vented bulbul Pycrorotus cafer). The birds lost weight and feathers and died after 16 to 45 days on a scorbutigenic ration. The scorbutic birds recovered with administration of ascorbic acid. The susceptibility to scurvy correlated well with the lack of activity in this species of the specific liver enzyme which is indispensable for ascorbic acid biosynthesis (L-gulonolactone oxidase). This enzyme was present in the liver of bank-myna Acridotheres ginginmanus) which was not susceptible to scurvy. 

Fig. 2.11. The capacity for ascorbic acid biosynthesis in avian liver and kidney microsomes in different orders of bird based on data from Chaudhuri Chatterjee (1969), using the biochemical classification of avian orders as shown in Fig. 1.3.

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