A new dimeric dehydrocorydaline alkaloid from vinegar-prepared Corydalis yanhusuo

Bidehydrocorydaline A (1), a new dimeric alkaloid of proberberine connected by a methylenedioxy group, was isolated from the vinegar-prepared Corydalis yanhusuo by various chromatographic methods, including column chromatography over macroporous adsorption resin and silica gel, reverse-phase MPLC, and semi-preparative HPLC. Its structure was determined by spectroscopic methods, including UV, IR, HR-ESI-MS, 1D and 2D NMR. Bidehydrocorydaline A (1) showed potent inhibitory activity against LPS-induced NO production in RAW 264.7 macrophages, with an IC₅₀ value of 2.33 ±0.57 μmol·L^-1.