High-yield, Enzymatic Synthesis of ¹⁴C- or ³H-Labeled 1-O-Valproyl-β-D-glucopyranuronic Acid, the Main Metabolite of Valproic Acid in Human

Abstract

A simple and high yield synthesis of radiolabeled 1-O-valproyl-β-D-glucopyranuronic acid was developed with the use of UDP-glucuronosyltransferase. Valproic acid, UDP-glucuronic acid, and UDP-glucuronosyltransferase were incubated for 48h at an optimum pH of 8.5. The enzymatic synthesis followed by column purification gave 51.8% and 52.5% yields of ¹⁴C- and ³H- labeled 1-O-valproyl-β-D-glucopyranuronic acid, respectively. The radiochemical purities of the ¹⁴C- and ³H-labeled substances were 98.8% and 99.2%, respectively. In contrast, the chemical synthesis using 2, 3, 4, 6-tetrabenzyl-D-glucopyranose and valproic acid resulted in much lower yield (6.8%) .