Pegaharmalines A and B, two novel beta-carboline alkaloids with unprecedented carbon skeletons from Peganum harmala

Pegaharmalines A (1) and B (2), two novel beta-carboline alkaloids with unprecedented carbon skeletons, were isolated from the seeds of Peganum harmala. Their structures were determined by spectroscopic methods and the absolute configuration of 1 was elucidated by CD analysis. 1 and 2 exhibited significant cytotoxicities on HL-60 cells with IC50 values of 9.4 and 13.6 mu M, respectively.