Acta Pharm. 53 (2003) 111-118

Toxicovigilance: New biochemical tool used in sulfonylurea herbicides toxicology studies

HAFID BELHADJ-TAHAR,^1* NICOLAS ADAMCZEWSKI,¹ BERTRAND NASSAR² and YVON COULAIS³

belhadj.h@chu-toulouse.fr

¹Poison Control Center and Department of Toxicology, Purpan University Hospital, Toulouse, France
²Laboratory of General & Nutritional Biochemistry, Purpan University Hospital, Toulouse, France
³Laboratory of Biophysics, Paul Sabatier University, Toulouse, France

In vitro toxic effects of sulfonylurea herbicides (thifensulfuron-methyl and metsulfuron-methyl) were evaluated according to a new protocol. Physiological conditions were reproduced in order to boost toxicovigilance. Sulfonylureas and their hydrolysis products were added to biological substrates such as urea, alanine, aspartic acid, alpha ketoglutarate, oxaloacetate, pyruvate and then incubated with some specific enzymes. Addition of these sulfonylureas and their degradation products did not significantly change the enzymatic activity of the urease, aspartate-aminotransferase, glutamate dehydrogenase, malate dehydrogenase and lactate dehydrogenase. However, the acid hydrolysis products inhibited up to 95% of the activity of the alanine-aminotransferase at low concentrations (0.27 micromol L^-1). Inhibition did not affect the mitochondrial aspartate-aminotransferase.

Keywords: sulfonylurea herbicides, toxicovigilance, toxic agent, alanine-aminotransferase, aspartate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, urease