The Assay of S-D-Lactoylglutathione in Biological Systems

A procedure for the assay of S-D-lactoylglutathione, the physiological intermediate of the glyoxalase system, in biological systems is described, together with sample storage, sample processing, and statistical evaluation. Specimen data are presented. S-D-Lactoylglutathione was assayed by reverse-phase high-performance liquid chromatography (HPLC) with spectrophotometric detection of the thiolester chromophore at 233 nm. The biological sample was deproteinized with perchloric acid and partially purified by strong anion-exchange solid-phase extraction prior to HPLC. The limit of detection was 3.7 nmol, the recovery 49 ± 4%, and the intra- and interbatch coefficients of variance 0.7 and 12%, respectively. The concentration of S-D-lactoylglutathione in whole blood from normal control human subjects was (mean ± SD, nmol/ml whole blood) 16.5 ± 4.4 (n = 8), and from diabetic patients 21.2 ± 9.2 (n = 25), which is a significant increase (P < 0.05) from normal controls. The assay of S-D-lactoylglutathione is of increasing interest in studies of the elevation of glyoxalase metabolites in diabetes mellitus and in investigations of the antiproliferative activity of S-D-lactoylglutathione.