Alloxanic acid

Alloxan forms an oxime (1007) which is the same compound, violuric acid, as that formed by nitrosation of barbituric acid likewise, a hydrazone and semicarbazone. Reduction of alloxan gives first alloxantin, usually formulated as (1008), and then dialuric acid (1004 R = OH) the steps are reversible on oxidation. Vigorous oxidation with nitric acid and alkaline hydrolysis both give imidazole derivatives (parabanic acid and alloxanic acid, respectively) and thence aliphatic products. Alloxan and o-phenylenediamine give the benzopteridine, alloxazine (1009) (61MI21300). 

The prototype reaction is the conversion of glyoxal into glycolic acid (equation 2), and here the benzilic acid rearrangement mechanism coincides with that for an intramolecular Cannizzaro reaction. The reaction is observed with other purely aliphatic a-diketones such as f-butyl 2,3-dioxobutyrate and cyclohexane-1,2-dione (equations 3 and 4), but the scope is limited in the aliphatic series by competing (c.g. aldol) reactions. Suitably constructed heterocyclic systems also rearrange, and the conversion of alloxan (3) into alloxanic acid (4) was among the first of the benzilic acid rearrangements to be discovered (equation 5). ... 

C3H402 Acrylic acid 25 4.25 C4H4N205 Alloxanic acid 25 6.64... 

Since the dose of GSH which affords complete protection against alloxan diabetes (2mM/kg. or 60 mg./100 gm.) is of the same order of magnitude as the GSH concentration in the various tissues, it is obvious that endogenous GSH is a naturally occurring protective compound. The injected alloxan must pass through the blood in order to reach the beta cells. In the blood plasma alloxan decomposes spontaneously to alloxanic acid (24) (Fig. 1) in the red cell alloxan reacts with the contained GSH in two ways. The alloxan is reduced to a nondiabetogenic derivative, dialuric acid (25),... 

J. A. Stekol Fed or injected. Alloxanic acid cannot be injected in any animals that we have tried. It is absolutely lethal—I think as lethal as the X-rays that have been discussed here. There is no evidence of alloxanic-acid production in vivo except the one that you just mentioned. I think of Dr. Lukens, although his evidence, from a strictly organic chemical viewpoint, I think, is not conclusive. Whether he isolated alloxanic acid or not is somewhat questionable. 

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