Antioxidant Activity, Phenolic Content, and Antioxidant Gene Expression in Genetic Resources of Sorghum Collected from Australia, Former Soviet Union, USA, Sudan and Guadeloupe

Functionality based on the biological activity of sorghum such as antioxidant activity is known worldwide for its excellence. In this study, we investigated the reactive oxygen species (ROS) scavenging activity, total phenolic and flavonoid contents, phenol compounds, and changes in antioxidant gene expression in sorghum seed cells collected from five countries (Australia, former Soviet Union, USA, Sudan, and Guadeloupe). Sorghum seeds were obtained from 12 genetic resources (K159041, K159042, K159078, K159081, K159088, K159089, K159093, K159097, K159100, K159096, K159048, and K159077). ROS scavenging activity was analyzed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,20-azinobis 3-ethylbenzothiazoline-6-sulfonate (ABTS). K159097 showed high antioxidant activity values of 33.52 ± 0.70 μg/mL (DPPH) and 271.06 ± 13.41 μg/mL (ABTS), respectively. The reducing power of the resources improved in a concentration-dependent manner, and 10 sorghum resources, except K159078 and K159048, showed high reducing power. K159042 had the highest total phenol content (231 ± 2.17 mg·GAE/g), and K159081 had the highest total flavonoid content (67.71 ± 5.38 mg·QE/g). Among the six phenolic compounds (protocatechuic acid, caffeic acid, p-coumaric acid, ferulic acid, taxifolin, and naringenin) analyzed, the compound with the highest content was taxifolin (203.67 ± 4.99 mg/L in K159093). K159041, K159042, and K159048 had the highest expression levels of superoxide dismutase (SOD), ascorbate peroxidase 1 (APX1), and catalase (CAT), which are indicators of antioxidant activity. An evaluation of the diversity of sorghum provided useful information on antioxidant activity, physicochemical content, and antioxidant gene expression in seed cells, suggesting that sorghum can be used as a biomaterial from natural resources.