M. Schultz, M. Leist, A. Elsner
1997
Citations
1
Influential Citations
35
Citations
Journal
Methods in enzymology
Abstract
Publisher Summary This chapter describes methods for the identification and estimation of urinary 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman ( α -CEHC) suitable to further investigate the conditions for α -CEHC excretion in humans and animals. α -CEHC is excreted as a sulfate or glucuronic acid conjugate. These conjugates must be hydrolyzed before determination to yield either the methyl esters or the free metabolites. Hydrolysis with a glucuronidase/sulfatase mixture leads to free α -CEHC. Due to the lack of a standard α -CEHC conjugate, it is not possible to test the recovery of α -CEHC released from conjugates. The conditions of enzymatic hydrolysis are therefore varied to determine if they are optimal. Increasing amounts of enzyme are used to hydrolyze a fixed amount of urine powder for increasing times, and the resulting α -CEHC is measured by means of gas chromatography/mass spectrometry (GC/MS). The hydrolysis of α -CEHC conjugates with methanolic HCl has been used to esterify the carboxylic acid derivatives of α -tocopherol and prevent lactonization.