Nanoemulsion in cancer therapy: Enhancing the therapeutic efficacy of capecitabine and 5-fluorouracil in colorectal cancer with thymoquinone nanoemulsion.

Chemotherapy is a significant treatment for cancer; however, it is frequently associated with deleterious side effects. Thymoquinone (TQ), a naturally occurring compound, has been reported to exhibit notable anti-cancer potential. The present study focuses on the in vitro effects of TQ-loaded nanoemulsion (TQ-NE) as an independent treatment and alongside the prevalent chemotherapeutic agents, 5-fluorouracil (5-FU) and capecitabine (CAP), on a colorectal cancer (HT-29) cell line. A TQ-NE formulation was synthesized and characterized, revealing an average particle size of 129.5 nm. The IC50 values for CAP, 5-FU, TQ, NE (carrier), and TQ-NE were 39.57, 61.01, 21.81, 218.4, and 15.12 μM, respectively. Cytotoxic effects were examined in both HT-29 cells and fibroblasts, revealing that TQ-NE enhanced the sensitivity of cancer cells to chemotherapeutic agents. When combined with 5-FU or CAP, TQ-NE produced a greater reduction in cell viability than TQ alone, indicating synergistic interaction. Flow cytometry analysis further revealed that TQ-NE induced distinct apoptotic responses compared to the control, whereas its combination with chemotherapy drugs showed a different pattern. These findings suggest that TQ-NE can enhance the cytotoxic activities of 5-FU and CAP in vitro. Furthermore, using lower concentrations of TQ-NE could potentiate the inhibitory effects of 5-FU and CAP, presenting a promising strategy for improving colorectal cancer (CRC) treatment outcomes while potentially reducing the adverse effects related to higher doses of conventional chemotherapy.