Comprehensive Analysis of Bioactive Phytoconstituents in Red Flesh of Dioscorea opposita Thunb. by UHPLC-Q-Orbitrap-HRMS.

Dioscorea opposita Thunb. cv. Tiegun (DTT) is used daily as food and medicine. However, there is confusion in removing the red flesh of DTT (RF), as the nutrient phytochemicals of RF are unclear. This study aimed to reveal the phytochemicals and antioxidant capabilities of RF. An ultra-high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) approach was employed to determine the comprehensive phytochemicals of RF, and the antioxidant activities (DPPH, ABTS, and FRAP) of the extracts were evaluated. A total of 249 phytochemicals were detected, including 150 primary metabolites, 68 secondary metabolites, and 31 other compounds. Notably, 166 differential metabolites (163 upregulated) were identified in RF relative to WF (white flesh). RF significantly increased the contents of primary metabolites (such as lipids, organic acids, and amino acids) and secondary metabolites (such as flavonoids and phenolic acids). RF showed higher antioxidant activity (DPPH, ABTS, and FRAP) than WF. The correlation analysis identified that most of the differential metabolites were significantly positively correlated with the antioxidant capacity. This is the first systematic and comprehensive qualitative analysis of the phytochemicals of RF. This study expands our knowledge of the bioactive constituents of RF and highlights the potential nutritional and medicinal values of DTT.