Hierarchically Structured CaCO ₃ –Gelatin Carriers for Oral Gastro-Protective Delivery of Broccoli Seed–Derived Isothiocyanates in Combined Chemotherapy of Colorectal Cancer

There is growing interest in the development of biologically active plant-derived compounds for various biomedical applications. Isothiocyanates (ITC), which occur naturally in cruciferous plants, can exhibit anticancer activity; however, their use is limited by poor stability and low bioavailability after oral administration. In this study, hierarchically structured carriers based on calcium carbonate (CaCO 3 ) microparticles embedded in gelatin particles (GP) were developed for oral delivery of ITC in combined chemotherapy of colorectal cancer (CRC). Broccoli seed-derived ITC were extracted and encapsulated inside developed carriers which showed pH-responsive and sustained-release properties. Swelling behavior, pH-dependent stability, and drug release profiles confirmed the suitability of the hierarchically structured carriers. Biological performance was evaluated using CT26 murine colon carcinoma cells through cytotoxicity, intracellular reactive oxygen species generation, and cellular uptake studies. Therapeutic efficacy was assessed in vivo using an orthotopic colorectal cancer model. Oral administration of encapsulated ITC in combination with clinically relevant 5-fluorouracil (5-FU) produces strong synergistic effect against CRC. Overall, the developed CaCO 3 –GP multifunctional platform improves drug stabilization, enables sustained release, and enhances the biological activity of ITC. This approach highlights the potential of integrating bioactive plant-derived compounds with advanced delivery systems to improve their applicability in cancer therapy.