Isoquinoline alkaloids isolated from Corydalis yanhusuo and their binding affinities at the dopamine D1 receptor

Abstract

Bioactivity-guided fractionation of Corydalis yanhusuo has resulted in the isolation of eight known isoquinoline alkaloids - tetrahydropalmatine, isocorypalmine, stylopine, corydaline, columbamine, coptisin, 13-methylpalmatine, and dehydrocorybulbine. The tertiary alkaloids were further analyzed by chiral HPLC to determine the ratios of d-and l-isomers. The isolated compounds were screened for their binding affinities at the dopamine D 1 receptor. Isocorypalmine had the highest affinity (Ki = 83 nM). The structure-affinity relationships of these alkaloids are discussed. © 2008 by the authors; licensee Molecular Diversity Preservation International.