Abstract
Chromatographic investigation of the aerial parts of the Rhazya stricta (Apocynaceae) resulted in the isolation of two new monoterpene indole alkaloids, 6-nor-antirhine-N-1-methyl (1) and razyamide (2), along with six known compounds, eburenine (3), epi-rhazyaminine (4), rhazizine (5), 20-epi-sitsirikine (6), antirhine (7), and 16-epi-stemmadenine-N-oxide (8). The chemical structures were established by various spectroscopic experiments. Compounds 1-8 exhibited cytotoxic effects against three cancer cells with IC50 values ranging between 5.1 +/- 0.10 and 93.2 +/- 9.73 mu M against MCF-7; 5.1 +/- 0.28 and 290.2 +/- 7.50 mu M against HepG2, and 3.1 +/- 0.17 and 55.7 +/- 4.29 mu M against HeLa cells. Compound 2 showed the most potent cytotoxic effect against all cancer cell lines (MCF-7, HepG2 and HeLa with IC50 values = 5.1 +/- 0.10, 5.1 +/- 0.28, and 3.1 +/- 0.17 mu M, respectively). Furthermore, compound 2 revealed a significant increase in the apoptotic cell population of MCF-7, HepG2, and HeLa cells, with 31.4 +/- 0.2%, 29.2 +/- 0.5%, and 34.9 +/- 0.6%, respectively. Compound 2 decreased the percentage of the phagocytic pathway on HepG2 cells by 15.0 +/- 0.1%. These findings can explain the antiproliferative effect of compound 2.