Copper (II)‐Enhanced Cytotoxic Effects of <i>Inula viscosa</i> Against Colon Cancer

Abstract Inula viscosa , a medicinal plant, is rich in bioactive compounds such as monoterpenoids, sesquiterpenoids, flavonoids, and glycosides, which contribute to its anti‐inflammatory, antipyretic, antiseptic, and antitumor properties. Recent studies suggest its cytotoxicity against various cancer cells is linked to the pro‐oxidant activity of its polyphenols. Transition metals like copper (II) may enhance this activity via the Fenton reaction. This study aimed to evaluate the cytotoxic, apoptotic, genotoxic, and reactive oxygen species (ROS)‐generating effects of I. viscosa extract, alone and combined with copper (II), on colon cancer cells (HT‐29). A 70% methanol extract was prepared from the plant's aerial parts. HT‐29 cells were treated for 24 h with varying doses of the extract, both alone and combined with a nontoxic dose (150 µM) of copper (II) sulfate (CuSO 4 ). Cytotoxicity, apoptosis, genotoxicity, and ROS levels were assessed using the MTT assay, AO/EB dual staining, comet assay, and H2DCF‐DA assay, respectively. The combination treatment significantly increased cytotoxicity, apoptosis, DNA damage, and ROS production compared to extract or copper alone. These findings suggest that the combination of I. viscosa and copper (II) exerts enhanced anticancer effects in HT‐29 cells through its pro‐oxidant activity.