Chemical synthesis of a 'GSA-pyrrole' and its reaction with Ehrlich's reagent

Article abstract of DOI:10.1016/S0040-4020(01)90187-5

A rational chemical synthesis of 4-acetyl-2-(2-carboxyethyl)-5-methylpyrrole (5), the product formed when glutamate-1-semialdehyde (GSA, 2) is reacted with acetylacetone in the first step of the quantitative analysis for GSA in biological media. Rates of reaction of the GSA-pyrrole (5) with Ehrlich's reagent (the second step in GSA quantitation) are compared with the rates of the reactions of well-characterized 'ALA-pyrroles' (3) and (4). Pyrrole (5) reacts more slowly with Ehrlich's reagent, and extinction coefficients for the corresponding Ehrlich's adducts were determined to be 46,000 for (3) and 865 for (5). These observations resolve the discrepancies observed in earlier quantitations of GSA and allow more accurate determinations of it in biological materials.