Epigallocatechin gallate (EGCG) decorating soybean seed ferritin as a rutin nanocarrier with prolonged release property in the gastrointestinal tract

The instability and low bioavailability of polyphenols limit their applications in food industries. In this study, epigallocatechin gallate (EGCG) and soybean seed ferritin deprived of iron (apoSSF) were fabricated as a combined double shell material to encapsulate rutin flavonoid molecules. Firstly, due to the reversible assembly characteristics of phytoferritin, rutin was successfully encapsulated within apoSSF to form a ferritin-rutin complex (FR) with an average molar ratio of 28.2: 1 (rutin/ferritin). The encapsulation efficiency and loading capacity of rutin were 18.80 and 2.98 %, respectively. EGCG was then bound to FR to form FR-EGCG composites (FRE), and the binding number of EGCG was 27.30 ± 0.68 with a binding constant K of (2.65 ± 0.11) × 10⁴ M⁻¹. Furthermore, FRE exhibited improved rutin stability, and displayed prolonged release of rutin in simulated gastrointestinal tract fluid, which may be attributed to the external attachment of EGCG to the ferritin cage potentially reducing enzymolysis in GI fluid. In summary, this work demonstrates a novel nanocarrier for stabilization and sustained release of bioactive polyphenols.