Cytotoxic Activity of Alkaloids from Papaver rhoeas growing in Lebanon

This paper represents the phytochemical properties of Lebanese Papaver rhoeas, from which five protopine alkaloids are isolated, namely; stylopine (1), canadine (2), sinactine (3), berberine (4), and epiberberine (5). This is the first report for the isolation of epiberberine (5) from the genus Papaver and canadine (2) from Papaver rhoeas, suggesting a new chemotype of Papaver rhoeas growing in Lebanon. The cytotoxic activity of the total ethanolic extract and the isolated alkaloids were determined by MTT assay on human colon cancer cells (HCT116), breast cancer cells (MCF7), human keratinocyte cell line (HaCaT), and non-cancerous colon cells (NCM460). The compounds showed dose-dependent inhibitory effect with highest activity for compound 4 against all cell lines. The activity of the alkaloids varied between the various cell lines indicating cell type specificity and suggesting different cell-compound interactions. IC50 values on normal cells was higher than cancer cell lines (>200 μM), indicating the selectivity of these compounds to cancer cells. It was noticed that the presence of methylenedioxy group at positions C-2 and C-3 rather than at position C-9 and C-10 potentiated the compound’s cytotoxic activity. Further studies are underway to explore the activity of these compounds at the molecular level.