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

Abstract

This study reports the isolation of four new β-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 rare β-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 annomontine β-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 IC₅₀ values of 12.39, 12.80, and 30.65 μmol·L⁻¹, respectively. Furthermore, compound 2 demonstrated selective cytotoxicity against HL-60 cells with an IC₅₀ value of 17.32 μmol·L⁻¹.

Keywords

β-Carboline alkaloids / Peganum harmala / Structure elucidation / Cytotoxic activity

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Funding

National Natural Science Foundation of China(81773604)

National Science and Technology Major Project of the Ministry of Science and Technology of China(2018ZX09735005)

Doctoral Scientific Research Fund Project of Nanyang Institute of Technology(510197)

Interdisciplinary Sciences Project, Nanyang Institute of Technology(520097)