Riboflavin chemical degradation

Hie problem has been approached mainly by adding labeled organic compounds to growing cultures of the riboflavin-producing organism. The riboflavin was then isolated from the fermentation broth, and the position of label in the vitamin determined. The methods employed for the chemical degradation of riboflavin are summarized in Fig. 1. 

III) and urea (II), the quinoxalinecarboxylic acid (III) is decarboxylated to 1-ribityl-l, 2-dihydro-2-keto-6,7-dimethylquinoxaline (IV), which in turn is oxidized to l-ribityl-2,3-diketo-l, 2,3,4-tetrahydro-6,7-dimethylquinoxaline (V). The first two of these proposed reactions would correspond to the chemical degradation of riboflavin or lumiflavin by dilute alkali and heat (cf. Fig. 1, A, B, C). Preliminary experiments with the appropriate quinoxalinecarboxylic acid and its lactam did not lead to their conversion to l-ribityl-2,3-diketo-l,2,3,4-tetrahydro-6,7-dimethylquinoxaline, although the chemical oxidation by hydrogen peroxide of 1-ribityl-l,2-dihydro-2-keto-6,7-dimethylquinoxaline-3-carboxylic acid has been indicated to occur. As a result, the possibility has been considered that products other than those pictured resulting in compounds (III) and... 

In 1933, R. Kuhn and his co-workers first isolated riboflavin from eggs in a pure, crystalline state (1), named it ovoflavin, and deterrnined its function as a vitamin (2). At the same time, impure crystalline preparations of riboflavin were isolated from whey and named lyochrome and, later, lactoflavin. Soon thereafter, P. Karrer and his co-workers isolated riboflavin from a wide variety of animal organs and vegetable sources and named it hepatoflavin (3). Ovoflavin from egg, lactoflavin from milk, and hepatoflavin from Hver were aU. subsequently identified as riboflavin. The discovery of the yeUow en2yme by Warburg and Christian in 1932 and their description of lumiflavin (4), a photochemical degradation product of riboflavin, were of great use for the elucidation of the chemical stmcture of riboflavin by Kuhn and his co-workers (5). The stmcture was confirmed in 1935 by the synthesis by Karrer and his co-workers (6), and Kuhn and his co-workers (7). 

Many ascidians live gregariously, and for some of these species conspecific chemical cues may play an important role in gregarious settlement of the larvae. The extracts of conspecific adults, larvae, or their conditioned seawater have been shown to contain metamorphosis inducers which have never been characterized.74-75 Recently, Fusetani and co-workers elucidated the structure of the metamorphosis inducer for the solitary ascidian Halocynthia roretzi, which was isolated from seawater conditioned by ascidian larvae.10 The compound isolated from the medium was identical to lumichrome, a compound known to be a degradation product of riboflavin (Figure 13.1). The origin of lumichrome in //. roretzi is not known at present. 

Alcohol is distilled up to a content of 96% in one or more stages. About 1 % of ethanol consists of fusel oils (degradation products of amino acids) which can be used as solvents for lacquers and resins. Solids from the processed liquor containing proteins, carbohydrates, mineral salts, riboflavin and other vitamins are used in poultry, swine and cattle feeds. C02 and H2 produced in butanol-acetone-butyric acid production can be used for the chemical synthesis of methanol and ammonia, or are burned. 

D-ribo-2,3,4,5-tetrahydroxypentyl)isoalloxazine and 7,8-dimethyl-10-ribityhsoalloxazine its formula is C17H20N4O6. Riboflavin has a molar mass of 376.37 grams (13.3 ounces). It is heat-stabile but easily degraded by light. Riboflavin was referred to as vitamin G in the early part of the twentieth century because it was recognized as a dietary factor needed for growth. Riboflavin was first isolated in 1879, and its chemical structure was determined in 1933. 

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