Hendersines J-M: Isoquinoline alkaloids from Corydalis hendersonii Hemsl. with cardiomyocyte protective and NO production inhibitory effects

Six isoquinoline alkaloids were identified from the alkaloid-rich fraction of Corydalis hendersonii Hemsl, including five previously undescribed isoquinoline alkaloids hendersines J-M (1a, 1b, and 2-4) and isobicuculline (5), a compound reported for the first time from a natural source. Their structures were elucidated based on spectroscopic analysis of HR-ESI-MS, 1D and 2D NMR, X-ray diffraction, and ECD. Compounds 1a and 1b represent a pair of rare three-nitrogen isoquinoline alkaloid enantiomers, while 2 and 3 are isoquinoline alkaloids featuring a benzo-fused N-heterocycle. Compounds 1a and 3 exhibited moderate protective effects against oxygen-glucose deprivation-induced H9c2 cells injury, 1b and 2 showed moderate inhibitory effects on NO production in lipopolysaccharide-induced RAW264.7 cells.