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As part of a bioprospecting program aimed at the discovery of anti-inflammatory agents from the Corydalis bungeana Turcz. (C. bungeana), five new hexahydrobenzophenanthridine alkaloids, corycaline A-E (1–5), along with four known alkaloids, were isolated from the whole plant of C. bungeana. Their structures including absolute configurations were elucidated on the basis of extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The inhibitory activities of the nine compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 mouse macrophage cells were determined; all tested compounds except 2 and 7 exhibited significant inhibitory effects with IC50 values in the range of 1.00–2.79 μM.

A novel hexahydrobenzophenanthridine alkaloid, corygaline A (1), was isolated from Corydalis bungeana Turcz. Its structure and absolute configuration were elucidated by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Corygaline A (1) is the first example of an alkaloid which features a 6/6/6/6/6-fused pentacyclic skeleton in nature. It exhibited significant NO production inhibitory activity in LPS-activated RAW264.7 macrophages with an IC50 value of 2.9 μM. A plausible biosynthetic pathway for 1 is also discussed.

pH-Zone-refining counter-current chromatography (pH-zone-refining CCC) was successfully applied for the large-scale separation of alkaloids from Corydalis bungeana. The crude extract was separated by a two-phase solvent system composed of petroleum ether–ethyl acetate–methanol–water (5:5:2:8, v/v) where triethylamine (10 mM) was added to the upper organic stationary phase as a retainer and hydrochloric acid (5 mM) to the aqueous mobile phase as a displacer. As a result, 285 mg of protopine, 86 mg of corynoloxine, 430 mg of coryno1ine, and 115 mg of acetylcorynoline were obtained from 3.0 g of crude extract in a one-step separation. The purities of these compounds were 99.1%, 98.3%, 99.0% and 98.5%, respectively, as determined by HPLC. The chemical structures of these isolated compounds were confirmed by ESI-MS, 1H-NMR and 13C-NMR.

Two flavonol O-glycosides identified as the 3-O-alpha-arabinopyranosyl(1'''--6'')-beta-glucopyranoside 7-O-beta-glucopyranosides of kaempferol and quercetin were isolated from the whole plant of Corydalis bungeana Turcz. together with eight known flavonol O-glycosides. Two isoquinolinone alkaloids were also obtained from the same source, including the new derivative, 6,7-methylenedioxy-2-(6-acetyl-2,3-methylenedioxybenzyl)-1(2H)-isoquinolinone. The structures were determined by spectroscopic methods (NMR and high-resolution MS).

A new alkaloid, (+)-13-epicorynoline, was isolated from the whole plant of Corydalis bungeana. Its structure was established by1H NMR, mass spectroscopy, 2D-COSY-1H NMR, UV, IR and the preparation of a derivative. The absolute configuration of the molecule was determined to be 11R,13R,14S by X-ray diffraction of its bromide salt.

From the herbs of CORYDALIS BUNGEANA, 16 alkaloids were isolated; 3 of them were identical with acetylcorynoline ( 2), corynoline ( 5), protopine ( 9), which had been obtained before from this plant. A further 11 known alkaloids: dihydrosanguinarine ( 1), acetylisocorynoline ( 3), 11-epicorynoline ( 4), corycavine ( 6), bicuculine ( 7), 12-hydroxycorynoline ( 8), scoulerine ( 12), cheilanthifoline ( 13), yuziphine ( 14), isoboldine ( 15), noryuziphine ( 16) were isolated for the first time from this plant. The tenth, named (+)-bungeanine, is a new alkaloid. Its structure has been established to be N-nor-5,14-dehydroacetylcorynoline. The conformation of (+)-bungeanine in solution is also discussed.