Integrated quantum chemical and in vitro investigation of Capsanthin antioxidant activity: Mechanism (HAT), cultivar variability, enhanced bioavailability, and key gene expression in peppers.

Capsanthin, the main bioactive component in red peppers, has potent antioxidant properties; however, its biosynthetic regulation and antioxidant mechanisms require further elucidation. In this study, we investigated 10 pepper cultivars through integrated quantum chemical calculations and assays. Theoretical calculations revealed that the antioxidant mechanism of capsanthin involves hydrogen atom transfer. Microwave-assisted extraction coupled with macroporous resin purification revealed significant interspecific variation in the capsanthin content. evaluation showed concentration-dependent antioxidant activity, with Bayan exhibiting the strongest capacity. The antioxidant properties and bioavailability of chili peppers increased after digestion. The results of the gene expression analysis revealed as the most highly expressed gene across cultivars, followed by and . Enzyme activity assays revealed that the activity of CRTR-β consistently exceeded that of CCS, which was correlated with gene expression levels.