Identification of 13 natural antioxidants in green calyx plum using AAPH, ABTS, and FRAP-coupled HPLC-DAD via QTOF-MS/MS

The novel application of a combined screening method, utilizing AAPH, ABTS, and FRAP assays with HPLC, is first used for screening natural antioxidants in Green Calyx plums (GCP). This method was assumed that the peak areas of compounds with antioxidant activity in HPLC chromatograms would be significantly reduced or disappeared after incubating with the AAPH, ABTS, and FRAP. The thirteen screened antioxidants can be identified by Q-TOF-MS/MS. kaempferol-3-O-rutinoside, narcissoside, and astragalin were first reported in GCP. respectively. The thirteen screened antioxidants were quantified simultaneously at their maximum absorption wavelengths, with concentrations ranging from 0.61 to 79.30 mg/g across three distinct flowering stages. Furthermore, the in vitro activity and molecular docking of oxidative stress-related enzyme xanthine oxidase (XOD) were utilized to evaluate the antioxidant capacity of the screened compounds. Consequently, our method effectively screens for antioxidants within complex mixtures, positioning GCP as a promising reservoir of natural bioactive compounds.