In Vitro Cytotoxic Effects of Cleistanthins B And Diphyllin on Colorectal Cancer

Objective: This study investigates the cytotoxic effects of cleistanthin B and diphyllin on colorectal cancer (CRC) cell lines to assess their potential as therapeutic agents for CRC. Methods: The cytotoxicity of cleistanthin B and diphyllin was assessed through the MTT assay to determine the 50% inhibitory concentrations (IC50) against several CRC cell lines, including HT-29, SW-480, and HCT-15. Apoptotic cell death was evaluated using acridine orange/ethidium bromide (AO/EB) dual staining and flow cytometry. Additionally, the effects of cleistanthin B and diphyllin were tested in combination with standard chemotherapy agents, such as 5-fluorouracil (5-FU) and oxaliplatin (Ox), to explore their potential synergistic effects. Results: Both cleistanthin B and diphyllin exhibited dose-dependent cytotoxicity across CRC cell lines, with cleistanthin B showing greater potency. IC50 values for cleistanthin B ranged from 3.6 ± 0.55 µg/mL in HT-29 cells to 26.7 ± 5.90 µg/mL in DU145 cells. Diphyllin displayed moderate cytotoxicity with higher IC50 values. Both compounds induced apoptotic changes, including chromatin condensation, nuclear fragmentation, and apoptotic body formation, as confirmed by AO/EB dual staining. The combination of cleistanthin B with 5-FU enhanced apoptosis in 5-FU-resistant HT-29 cells, suggesting a synergistic effect. Conclusion: Cleistanthin B and diphyllin exhibit significant cytotoxicity against CRC cells, with cleistanthin B being more potent. Both compounds effectively induce apoptosis and may enhance the anticancer activity of 5-FU, indicating their potential as adjunct therapies for CRC treatment.