Peganumine A, a β‑Carboline Dimer with a New Octacyclic Scaffold from Peganum harmala

Peganumine A (1), a new dimeric β-carboline alkaloid characterized by a unique 3,9-diaza­tetra­cyclo­[6.5.2.01,9.03,8]­pentadec-2-one scaffold, was isolated from the seeds of Peganum harmala. The structure including the absolute configuration was determined by spectroscopic data, X-ray crystallography, ECD calculation, and CD exciton chirality approaches. Compound 1 showed moderate cytotoxic activity against MCF-7, PC-3, and HepG2 cells and selective effects on HL-60 cells with an IC50 value of 5.8 μM.