Separation of protoberberine quaternary alkaloids from a crude extract of Enantia chlorantha by centrifugal partition chromatography

Abstract

High-performance centrifugal partition chromatography (HPCPC) has been successfully applied to the separation of four protoberberine quaternary alkaloids, namely palmatine, jatrorrhizine, columbamine and pseudocolumbamine, from a methanolic extract (M 1, 1.47 g) of Enantia chlorantha Oliver stem bark. For their isolation, two successive biphasic solvent systems composed of dichloromethane–methanol–water (48:16:36, v/v) were selected. The aqueous-rich phase was the stationary phase and the organic-rich phase was the mobile phase. The first system, containing potassium perchlorate, allowed to isolate 600 mg of palmatine, and to obtain 146 mg of a mixture (M 2) containing only jatrorrhizine, columbamine and pseudocolumbamine. The second biphasic system, prepared with water alkalinized with sodium hydroxide, was employed to isolate the M 2 components. This system applied to the purification of 70 mg of M 2 allowed to obtain 16 mg of jatrorrhizine and 13 mg of columbamine. To obtain pseudocolumbamine (16 mg), the elution mode was reversed, the aqueous-rich phase becoming the mobile phase, and the organic-rich phase becoming the stationary one. Analytical reversed-phase high-performance liquid chromatography, NMR, high-resolution mass spectrometry and UV spectrometry were used to verify the identity and the purity of the isolated compounds.