High-performance thin-layer chromatography assay for epoxide hydrolase activity and the determination of phenoxypropane-1,2-diols

A simple, rapid and sensitive high-performance thin-layer chromatographic assay for the determination of epoxide hydrolase activity in rat liver homogenates is described. It is extended to the determination of a series of phenoxypropane-1,2-diols. The hydrolase assay has the advantages of using a readily available substrate, 2,3-epoxypropyl 4-methoxyphenyl ether, of multiple sample application, and of the simultaneous determination of reaction product (diol) as well as unchanged substrate (epoxide). The use of an internal standard, 4-nitroanisole, results in high sensitivity and good reproducibility of the proposed method. The limit of diol detection is 20 pmol.