Neuroprotective Effects of Chemical Constituents of Leaves of Euonymus hamiltonianus Wall.

Euonymus hamiltonianus Wall. is considered a medicinal plant and is used to treat pain, cough, dysuria, and cancer, but a clear phytochemical investigation of its biological activities has yet to be performed. Investigation of chemical constituents of the leaves of Euonymus hamiltonianus Wall. led to the isolation of three new compounds by chromatography techniques, euonymusins A–C (1, 10, and 11), and the acquisition of new spectroscopic data for euonymusin D (2), along with the identification of ten known compounds. The chemical structures of the compounds were established using extensive spectroscopic techniques, including NMR, MS, and hydrolysis, and compared with the published data. These compounds were tested in vitro for their inhibitory effects on beta amyloid production (Aβ42). Compounds 13 and 14 displayed weak inhibition, with IC50 values ranging from 53.15 to 65.43 µM. Moreover, these compounds were also assessed for their inhibitory effects on nitric oxide production. Of these compounds, 3, 4, and 14 displayed inhibitory effects on NO production, with IC50 values ranging from 14.38 to 17.44 µM. Compounds 3, 4, and 14 also suppressed LPS-induced expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein.