Structure and colon-targeted releasing property of resistant octenyl succinate starch

Granular and crystalline structures of resistant octenyl succinic anhydride (OSA) modified corn starch were characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffraction. As a colon-targeted delivery carrier, the releasing property of resistant OSA-modified starch was also investigated by In-vitro model. Enhanced succinylation of starch considerably increased the enzyme and acid resistibility to digestion, indicating the improvement of starch colon-targeting property as the degree of substitution (DS) increased. From In-vitro releasing assay, the resistant OSA-modified corn starch based matrix tablets could deliver bioactive components to the colon when the RS content and hydrophobicity were suitable. The relationship between the structure and In-vitro release properties of resistant OSA-modified corn starch suggests that an optimal DS and crystalline:amorphous ratio can be responsible for 5-ASA release. The matrix tablets used resistant OSA-modified corn starch with moderate DS (0.60) and V-type crystal morphology co-exist with the amorphous structure as carrier show good colon-targeted releasing properties.

► Enhanced succinylation can improve the colon-targeting property of starch. ► Resistant octenyl succinate starch shows a less-ordered V-type polymorph structure. ► DS and crystalline: amorphous ratio are responsible for the colon-targeting release.