Tomentediline A: A isoquinoline alkaloids with undescribed carbon skeleton from Corydalis tomentella

Two undescribed isoquinolines (1–2), including one undescribed carbon skeleton isoquinoline together with six known ones (4–9) as well as an undescribed amide (3) and three known ones (10–12) were isolated from C. tomentella. Their planar structures and absolute configurations were elucidated by extensive analyses of UV, NMR, HRESIMS, DP4+ statistical analysis and ECD calculations, respectively. Tomentediline A (1) is an isoquinoline alkaloid dimer that forms an undescribed carbon carbon bond at the C-13 position of (2H)-protoberberine in a natural product discovered for the first time. Meantime, 1 exerted moderate cytotoxicity against the U251 cell lines, indicating that the undescribed dimer skeleton of isoquinoline compound has the potential for anti-glioma.