Alloxan

Alloxan or mesoxalylurea is an organic compound based on a pyrimidine heterocyclic skeleton.

This compound has a high affinity for water and therefore exists as the monohydrate.

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Discovery

The compound was discovered by Justus von Liebig and Friedrich Wöhler following the discovery of urea in 1828 and is one of the oldest named organic compounds that exist.

Etymology

The name is derived from allantoin, a product of uric acid excreted by the fetus into the allantois and oxaluric acid derived from oxalic acid and urea, found in urine.

Synthesis

The original recipe for Alloxan was by oxidation of uric acid by nitric acid. Alloxan is a strong oxidizing agent and it forms a hemiacetal with its reduced reaction product dialuric acid (in which a carbonyl group is reduced to a hydroxyl group) which is called alloxantin.

Commercial use

Alloxane is a raw material for the production of the purple dye Murexide. Carl Wilhelm Scheele discovered the dye in 1776. Murexide is the product of the complex in-situ multistep reaction of alloxantin and gaseous ammonia.

Murexide results from the condensation of the unisolated intermediate uramil with alloxan, liberated during the course of the reaction.

Scheele sourced uric acid from human calculi (such as kidney stones) and called the compound lithic acid. William Prout investigated the compound in 1818 and he used boa constrictor excrement with up to 90% ammonium acid urate.

Liebig and Wöhler in the nineteenth century coined the name murexide for the dye after the Trunculus Murex which is the source of the Tyrian purple of antiquity.

Primo Levi in his world famous novel The Periodic Table in chapter Nitrogen considers pythons as a source for alloxane on behalf of a lipstick producer but he is turned down by the director of the Turin zoo because the zoo already has lucrative contracts with cosmetics companies (his attempts with chicken dung end in misery).

Impact upon beta cells

Because it selectively kills the insulin-producing beta-cells found in the pancreas, Alloxan is used to induce diabetes in laboratory animals. This occurs most likely because of selective uptake of the compound due to its structural similarity to glucose as well as the beta-cell's highly efficient uptake mechanism (GLUT2).

A 2005 website article links the presence of alloxan as an additive in white flour to the occurrence of diabetes and offers vitamine E as a countermeasure.^[1] However, no scientific evidence to date substantiates this health food claim. As a matter of fact, scientific evidence shows that alloxan is not even toxic to the human beta-cell, even in very high doses, probably due to differing glucose uptake mechanisms in humans and rodents.^[2][3]This drug is, however, toxic to the liver and the kidneys in high doses.

References

1. ^ http://www.newstarget.com/008191.html
2. ^ Tyrberg B, Andersson A, Borg L (2001). "Species differences in susceptibility of transplanted and cultured pancreatic islets to the beta-cell toxin alloxan". Gen Comp Endocrinol 122 (3): 238-51. PMID 11356036.
3. ^ Eizirik D, Pipeleers D, Ling Z, Welsh N, Hellerström C, Andersson A (1994). "Major species differences between humans and rodents in the susceptibility to pancreatic beta-cell injury". Proc Natl Acad Sci U S A 91 (20): 9253-6. PMID 7937750.