Comparison of the contents of phenolic compounds including flavonoids and antioxidant activity of rice (Oryza sativa) and Chinese wild rice (Zizania latifolia).

The contents of phenolic compounds, especially flavonoids, and antioxidant activity of rice (Oryza sativa, Os) and Chinese wild rice (Zizania latifolia, Zl) harvested in China were compared. Zl possessed significantly higher contents of total phenolics, flavonoids, and proanthocyanidins and exhibited higher antioxidant activity than in the Os Xian group, the Os Geng group, and red rice. The flavonoid contents of Os and Zl were compared using a UHPLC-QqQ-MS-based metabolomics approach. A total of 159 flavonoids were identified, among which 78 showed differential expression (72 up-regulated and six down-regulated in the Zl group). The Kyoto Encyclopaedia of Genes and Genomes annotation and classification indicated that the differentially expressed flavonoids were mainly related to anthocyanin biosynthesis. Moreover, candidate genes for flavonoid biosynthesis in Os and Zl were identified in this study. Compared with non-pigmented and red rice, Zl may be more nutritious and is thus considered a better source of natural antioxidants.