Pumpkin seed protein as a carrier for Astaxanthin: Molecular characterization of interactions and implications for stability

Abstract

This study investigated pumpkin seed protein (PSP) as a carrier for astaxanthin (AST). Interaction mechanisms revealed through fluorescence spectroscopy and molecular docking, showed that hydrogen bonds and Van der Waals forces form the PSP-AST complex. AST binding altered PSP's secondary structure, increasing α-helix (7.32 %) and β-sheet (14.49 %) content while reducing β-turn (12.55 %) and random coil (9.26 %) content. Temperature significantly affected AST degradation, with higher stability observed in the PSP-AST complex. The degradation process was non-spontaneous, with a higher activation energy for complexed AST (26.53 KJ/mol) than free AST (14.69 KJ/mol). Additionally, AST reduced PSP oxidation by 16 % in oxidative conditions, and PSP protected AST during in vitro digestion. This study provides key insights for enhancing AST stability, highlighting its potential applications in the food and pharmaceutical industries.

Keywords: Carotenoids; Degradation; In vitro digestion; Molecular docking; Oxidative stability.