(±)-Pheharmines A-B, two pairs of racemic alkaloids with a morpholino[4,3,2-hi]β-carboline core, from the roots of Peganum harmala

Two pairs of unprecedented beta-carboline-phenylpropanoid heterogeneous alkaloids, (+/-)-pheharmines A-B (1-4), characterized by a morpholino[4,3,2-hi]beta-carboline core with two chiral centers, were isolated from the roots of Peganum harmala. The structures, including their absolute configurations, were identified using spectroscopic analyses and electronic circular dichroism (ECD) calculations. The biosynthetic hypothesis for the formation of pheharmines A-B was proposed. Compounds 1-4 exhibited moderate cytotoxic activities against HL-60 cell lines.

Automated summary

Two pairs of novel beta-carboline-phenylpropanoid alkaloids with a unique chemical structure and moderate cytotoxic activity were isolated from the roots of Peganum harmala. The structures and configurations were determined by spectroscopic analyses and calculations.