Chemical components from the seeds of: Catalpa bungei and their inhibitions of soluble epoxide hydrolase, cholinesterase and nuclear factor kappa B activities

Two new chlorinated iridoids, named bungosides A (1) and B (2), were isolated from the seeds of Catalpa bungei (family Bignoniaceae). Their structures were elucidated on the basis of NMR analysis. Twenty known compounds (3-22) were also characterized, including in one case (6-O-p-hydroxybenzoylglutinoside, 3) the assignment of the absolute configuration by employing electronic circular dichroism (CD) and time-dependent density functional theory (TDDFT) calculations. Compounds 1-3 were unusual cage-like iridoids with an oxygen bridge between C-3 and C-10. Among the isolates, ursolic acid lactone (14) was the most active soluble epoxide hydrolase (sEH) inhibitor with an IC50 19.1 ± 0.8 μM. In addition, d-pinoresinol (19) and ladanein (21) displayed selectively inhibitory effects on butyrylcholinesterase (BChE) with IC50 of 31.5 ± 0.4 μM and 33.0 ± 2.3 μM, respectively, but not acetylcholinesterase (AChE) activity, and only compound 18 suppressed NF-κB activity in HepG2 cells (IC50 21.53 ± 2.37 μM).