Preparation And Physicochemical Property Analysis Of Ferritin-rutin Composites

Rutin is a common dietary flavonoid with important pharmacological activities.However, its application in the food industry and medical field is limited mainly because of its poor water-solubility and instability towards light and thermal treatment. Ferritins are composed of 24 structurally identical or different subunits that assemble into a very robust protein cage (the external diameter is 12 nm and the internal cavity is 8 um). Ferritins are widely distributed in nature with a shell-like structure which contributes to improving the water-solubility and thermal stability of the bioactive molecules by encapsulation. However,the use of EGCG-modified ferritin to load rutin molecule and its digestion properties in vitro have been hardly reported. In current paper, with purified recombinant H-2 ferritin (rH2F),rutin and EGCG as material, rH2F-rutin composite (FR) and EGCG-modified rH2F-rutin composite (FRE) were successfully prepared, followed by their physical and chemical properties analysis. Main results were as follows:1. rH2F was separated by microbial culture, sonication, salting-out and column chromatography, and the purity reached electrophoretic homogeneity standards, thus providing sufficient experimental materials for the subsequent study.2. Based on the characteristics of globular structure rH2F subunit and reversible assembly, FR was successfully prepared, and and the optimum preparation conditions were obtained. The highest rutin encapsulation rate and loading rate were 18.8% and 2.98%,respectively, the average per molecule of rH2F encapsulated 28 of rutin molecules. Compared with the free rutin, water solubility, ultraviolet radiation and thermal stability, storage stability of rutin that upon such encapsulation were improved significantly. Moreover, rutin had little effect on the secondary structure of rH2F, and retained some antioxidant capacity of rutin.3. Ferritin is susceptible to protease degradation in the stomach, while EGCG modified FR outer surface can increase its anti-digestibility. The results ilndicated that about 27 EGCG molecules were bound to one FR molecule by fluorescence titration, and the two were interacted by hydrophobic van der Waals interactions.4. The FRE was found to be 17.7% and 2.81% in rutin encapsulation rate and loading rate, respectively, which meant 26.5 rutin molecules could be encapsulated per EGCG modified rH2F. The results showed that EGCG modified ferritin did not affect the embedding rate. Compared to free rutin and FR, FRE increased the storage stability of rutin. Furthermore,rutin had a more pronounced sustained-release effect on simulated gastrointestinal (GI)digestion in vitro.In conclusion, the study improved the water solubility and stability of rutin and improved its bioavailability in the gastrointestinal tract, which is of great significance in the field of food and drug applications, and provided a theoretical basis for the development of natural, safe and efficient nutritional supplements.