Spray drying technique was adopted in this study to prepare astaxanthin ester microcapsules with four different wall materials (Arabic gum, inulin, chitosan and fucoidan), which were characterized for encapsulation efficiency, flowability and other physicochemical indexes. Scanning electron microscopy (SEM) was adopted to observe their microstructure, and their thermal stability at different temperatures was evaluated. Finally, the effects of the four wall materials on the bioavailability of astaxanthin in Institute of Cancer Research (ICR) mice were explored. The results showed that the highest encapsulation efficiency of (96.64 ± 0.33)% was obtained when using Arabic gum as wall material. SEM showed that both inulin and fucoidan microcapsules were nearly spherical in morphology with the most complete structure. Astaxanthin ester-fucoidan microcapsules had the best thermal stability with an activation energy of 74.06 kJ/mol, followed by inulin-astaxanthin ester microcapsules. The thermal stability was significantly correlated with the micromorphology but poorly correlated with the encapsulation efficiency. Animal experiments indicated that compared with inulin and Arabic gum, use of chitosan and fucoidan as wall material resulted in significantly higher bioavailability of microencapsulated astaxanthin, evidencing that the promoting effect of microencapsulation on astaxanthin ester bioavailability was closely related to the type of wall material. To sum up, fucoidan-astaxanthin ester microcapsules were the best in terms of stability and bioavailability. This study provides the theoretical basis and data support for the construction of high-quality polysaccharide-based microcapsules loaded with astaxanthin ester.

A novel and reactive oxygen species (ROS) responsive astaxanthin phenylboronic acid derivative (AstaD-PBA) was constructed by grafting phenylboronic acid (PBA) onto astaxanthin succinate diester (AstaD), and its chemical structure and physicochemical property were identifi ed. AstaD-PBA could effectively improve the ROS quenching ability in the lipopolysaccharide (LPS)-induced RAW264.7 cell inflammation model. Then, the bioactivity of AstaD-PBA was studied by 4 zebrafi sh ROS-responsive infl ammatory models induced by LPS, copper (Cu²⁺), high-fat diet, and dextran sodium sulfate (DSS). The results suggest that AstaD-PBA might have high biosafety and the best effect on ulcerative colitis (UC) induced by DSS. Furtherly, AstaD-PBA signifi cantly alleviated and treated weight loss and colonic shrinkage, inhibited infl ammatory cytokines, and maintained microbiota homeostasis to improve UC in C57BL/6J mice. Alistipes and Oscillibacter were expected to be considered UC marker fl ora according to the Metastats analysis and Pearson correlation Mantel test (P < 0.01) of 16S rRNA gene sequencing data. In conclusion, AstaD-PBA has been promised to be a functional compound to improve UC and maintain intestinal microbiota homeostasis.