Discovery of soluble epoxide hydrolase inhibitors from natural products

Abstract

With the goal of developing soluble epoxide hydrolase (sEH) inhibitors with novel chemical structures, the sEH inhibitory activities of 30 natural compounds were evaluated using both a fluorescent substrate, 3-phenyl-cyano(6-methoxy-2-naphthalenyl)methyl ester- 2-oxiraneacetic acid, and a physiological substrate, 14,15-epoxyeicosatrienoic acid. To evaluate the selectivity of sEH inhibition, the inhibition of microsomal epoxide hydrolase (mEH), which plays a critical role in detoxification of toxic epoxides, was determined using human liver microsomes. Honokiol and β-amyrin acetate, isolated from Magnolia officinalis and Acer mandshuricum, respectively, displayed strong inhibition of sEH activity, with respective IC50 values of 0.57μM and 3.4μM determined using the fluorescent substrate, and 1.7μM and 6.1μM determined using 14,15-epoxyeicosatrienoic acid. mEH activity was decreased to 49% or 61% of control activity by 25μM honokiol or β-amyrin acetate, respectively. These results suggest that β-amyrin acetate and honokiol exhibit sEH inhibitory activity, although their sEH selectivity should be improved.