Diazo bond

The prototypical aminosalicylate is sulfasalazine, which is comprised of mesalamine linked by a diazo bond to the carrier molecule sulfapyridine. This linkage prevents premature absorption of mesalamine in the small intestine. Once sulfasalazine is delivered to the colon, bacterial degradation of... 

Newer mesalamine products utilize non-sulfapyridine methods for drug delivery. Olsalazine uses two mesalamine molecules linked together, while balsalazide uses the inert carrier molecule 4-aminobenzoyl-P-alanine. Both drugs use a diazo bond similar to sulfasalazine. Other mesalamine formulations are pH-dependent formulations that release mesalamine at various points throughout the GI tract. 

Diazonium groups react with active hydrogen sites on aromatic rings to give covalent diazo bonds. Generation of a diazonium functional group usually is done from an aromatic amine... 

Crosslinking using diazonium compounds usually creates deeply colored products characteristic of the diazo bonds. Occasionally, the conjugated molecules may turn dark brown or even black. The diazo linkages are reversible by addition of 0.1 M sodium dithionite in 0.2 M sodium borate, pH 9.0. Upon cleavage, the color of the complex is lost. 

Two Molecules Conjugated with a Diazo-bond-Forming Cross-linking Agent... 

Figure 8.3 Crosslinking agents that form diazo bonds may be cleaved using sodium dithionite.

Figure 11.17 The diazonium group of p-diazobenzoylbiocytin can react with tyrosine or histidine residues in proteins to form diazo bonds.

Figure 11.18 The diazonium group of p-diazobenzoylbiocytin can couple to the C-8 position of guanidine bases in nucleic acids, forming diazo bonds.

Diazonium groups are able to couple at the C-8 position of adenosine or guanosine residues, forming diazo bonds. p-Aminobenzoyl biocytin can be used in this reaction to add a biotin handle to purine bases within oligonucleotides (Chapter 8, Section 3.5). This biotinylation reagent contains a 4-aminobenzoic acid amide derivative off the... 

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