Metabolomics and biochemical analyses revealed metabolites important for the antioxidant properties of purple glutinous rice

Glutinous rice can be applied to many fields including brewing industry, medicine, cosmetics and food processing. However, we know very little about the basic metabolite information of glutinous rice. In this study, we identified the phenol and flavonoid metabolites in purple glutinous rice and white glutinous rice, and elucidated the relationship between metabolites and total antioxidant capacity. The results demonstrated that flavonoids contents, oligomeric proanthocyanidin contents and total antioxidant capacity of purple glutinous rice were significantly higher than those of white glutinous rice. We identified 390 differential metabolites between the purple glutinous rice and white glutinous rice by LC–MS metabolomics. Correlation analysis results showed that flavonoid and phenol metabolites contents were strongly correlated with total antioxidant capacity. This study further clarified that the pantothenic acid, pebrellin, l-glutamic acid, eupatilin, diosmin, and diosmetin could be used as candidate metabolite markers for antioxidant capacity screening in glutinous rice grains.