β-Carboline alkaloids from the roots of Peganum harmala L.

This study reports the isolation of four newβ-carboline alkaloids(1−4)and six previously identified alkaloids(5−10)from the roots of Peganum harmala L.Among these compounds,1 and 2 were characterized as rareβ-carboline-quinazoline dimers exhibiting axial chirality.Compound 3 possessed a unique 6/5/6/7 tetracyclic ring system with an azepine ring,and compound 4 was a novel annomontineβ-carboline.The structures of these compounds were elucidated by spectroscopic data and quantum mechanical calculations.The biosynthetic pathways of 1−3 were proposed.Additionally,the cytotoxicity of some isolates against four cancer cell lines(HL-60,A549,MDA-MB-231,and DU145)was evaluated.Notably,compound 4 exhibited significant cytotoxicity against HL-60,A549,and DU145 cells with IC_(50) values of 12.39,12.80,and 30.65μmol·L^(−1),respectively.Furthermore,compound 2 demonstrated selective cytotoxicity against HL-60 cells with an IC_(50) value of 17.32μmol·L^(−1).