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.