Sodium alginate beads incorporating hydroxypropyl distarch phosphate for colon-directed curcumin delivery with...

Curcumin-loaded hydrogel beads were developed using hydroxypropyl distarch phosphate (HDP) and sodium alginate, including octenyl succinic anhydride (OSA)-modified alginate, for colon-directed delivery and anticancer evaluation against Caco-2 cells. Alginate was modified with 1%, 2%, and 3% OSA, yielding degrees of substitution (DS) of 0.011 ± 0.005, 0.025 ± 0.002, and 0.041 ± 0.006, representing the minimum, FDA-permitted, and maximum substitution levels, respectively. The encapsulation efficiency of the lyophilized bead formulations (HDP-SA, HDP-SA₁, HDP-SA₂, and HDP-SA₃) increased from 86.45 ± 0.22% to 95.23 ± 0.63%, demonstrating that OSA modification improved encapsulation efficiency. The formulations were characterized using FTIR, TGA, XRD, and SEM, while their swelling behavior and in vitro release profiles were evaluated under simulated gastric (pH 1.2) and intestinal (pH 7.4) conditions. The freeze-dried beads effectively protected curcumin during simulated gastrointestinal transit and provided sustained release during the intestinal phase, supporting their potential for colon-directed delivery. MTT assays demonstrated concentration-dependent cytotoxicity against Caco-2 cells, with IC₅₀ values of 187.6 ppm for HDP-SA and 92.8 ppm for HDP-SA₂. These findings suggest that OSA-modified alginate hydrogel beads represent a promising carrier for colon-directed curcumin delivery by improving encapsulation efficiency, providing sustained release, and enhancing in vitro anticancer activity.