Baicalensines A and B, Two Isoquinoline Alkaloids from the Roots of Thalictrum baicalense

Baicalensines A (1) and B (2) were isolated from the roots of Thalictrum baicalense and structurally characterized using spectroscopic data, C-13 NMR calculations, and the CASE algorithm. Compound 1, representing a new class of alkaloid dimers, contains berberine conjugated to a ring-opened isoquinoline. Compound 2 is the first reported natural benzylisoquinoline bearing a formyl group at C-3. Plausible biosynthetic pathways are proposed. Compound 1 exerted moderate cytotoxicity against the Caco-2 and HL-60 cell lines.