In vitro preparation of N-ethylpyrrolidone substituted flavanols in tea and their starch graft copolymers

N-Ethyl-pyrrolidone-substituted-flavan-3-ols (EPSFs), flavonoid alkaloids with diverse bioactivities, are challenging to extract from tea leaves. This study synthesized EPSFs in vitro using epigallocatechin gallate (EGCG) and theanine under simulated hydrothermal conditions. Column chromatography yielded EPSFs with 85.2% purity. Evaluated in SH-SY5Y/APP695 (SHswe) cells, a Alzheimer’s disease (AD) model, EPSFs exhibited potential anti-AD effects. A starch-EPSFs graft copolymer was synthesized via free radical-mediated polymerization. Compared to starch-EGCG, the starch-EPSFs copolymer demonstrated enhanced DPPH•/ABTS• + radical scavenging and α-amylase inhibition within specific concentration ranges. This work advances efficient EPSFs production and highlights their therapeutic potential for AD. The antioxidant starch-EPSFs copolymer also holds promise for material science, medical, and industrial applications, offering a novel strategy for functional biomaterial design. In this study, we synthesized and purified EPSFs in vitro, and investigated their related biological activities. In order to broaden the application of EPSFs, we synthesized EPSFs starch graft copolymers and evaluated their antioxidant capacity. • We proposed an effective method for the in vitro synthesis and purification of EPSFs. • The synthesized EPSFs were shown to possess potential anti-AD capabilities. • The starch-EPSFs graft copolymer showed strong ability to scavenge DPPH and ABTS radicals and inhibit α-amylase.