Qualification of flavonoids of three sorghum bran varieties by untargeted metabolomics

Sorghum bicolor is a source of many bioactive components, such as polyphenols. Those components are present especially in its bran, which is often removed in industrial processes through decortication. In that sense, this work aimed to analyze the polyphenol content, especially free flavonoids, from the bran of a newly developed variety compared to other commercially available varieties. The samples were white sorghum TDN® Sorgho, red sorghum Mini Sorgho, and the newly developed red sorghum RILN-156. First, the decortication was done to obtain the bran samples and those were triturated and then sieved. An untargeted metabolomics analysis (with LC/MS and CE/MS) was done to analyze the different components and identify the free flavonoids. For the general quantification analysis, instead of quantifying by target analysis, colorimetric methods were used to validate the metabolomics analysis. For this, the polyphenol content was extracted with 70% methanol. The antioxidant potential was also investigated using a DPPH assay. The results have shown that the flavonoid content was significant in these samples, especially in the newly developed RILN-156, with 19 flavonoids identified. RILN-156 also presented higher antioxidant capacity than the conventional varieties, a promising finding for its use to prevent chronic diseases, which will be further investigated.