Comprehensive evaluation of nutritional components, bioactive metabolites, and antioxidant activities in diverse sorghum (Sorghum bicolor (L.) Moench) landraces

Sorghum, one of the prospective crops for addressing future food and nutrition security, has received attention in recent years due to its health-promoting compounds. It is known that several environmental and genetic factors affect the metabolite contents of dietary crops. This study investigated the diversity of different nutrients, functional metabolites, and antioxidant activity using three different assays in 53 sorghum landraces from Korea, China, Japan, Ethiopia, and South Africa. The effects of origin and seed color variations were also investigated. Total phenolic (TPC), total tannin (TTC), total fat, total protein, total dietary fiber, and total crude fiber contents all varied significantly among the sorghum landraces (p < 0.05). Using a gas chromatography-flame ionization detector, palmitic, stearic, oleic, linoleic, and linolenic acids were detected in all the sorghum landraces, and their content significantly varied (p < 0.05). Furthermore, four 3-deoxyanthocyanidins (luteolinidin, apigeninidin, 5-methoxyluteolinidin, and 7-methoxyapigeninidin) and two flavonoids (luteolin and apigenin) were detected in most of the landraces using liquid chromatography-tandem mass spectrometry, and their concentrations also significantly varied. Statistical analyses supported by multivariate tools demonstrated that seed color variation had a significant effect on TPC, TTC, DPPH• and ABTS•+ scavenging activities, and ferric-reducing antioxidant power, with yellow landraces having the highest and white landraces having the lowest values. Seed color variation also had a significant effect on dietary fiber, linoleic acid, linolenic acid, and luteolin contents. In contrast, all nutritional components and fatty acids except total protein and oleic acid were significantly affected by origin, while most 3-deoxyanthocyanidins and flavonoids were unaffected by both origin and seed color differences. This is the first study to report the effect of origin on sorghum seed metabolites and antioxidant activities, laying the groundwork for future studies. Moreover, this study identified superior landraces that could be good sources of health-promoting metabolites.