Isoquinoline alkaloids from the Corydalis tomentella with potential anti-hepatoma and antibacterial activities

Six undescribed isoquinolines, including one rarely reported N-benzyl isoquinoline together with sixteen known ones were isolated from C. tomentella. Their planar structures and absolute configurations were elucidated by extensive analyses of UV, IR, NMR, HRESIMS, DP4+ probability analysis as well as ECD calculations. Biological evaluations revealed that 3,4-2H-tomentelline C (6) showed significant cytotoxicity (IC₅₀ = 7.42 μM) against the HepG2 cell line while (1'R, 2'S)-coptichine B (3) exhibited stronger antibacterial activities.