Comparative analysis of the metabolite compositions and antioxidant capacity of waxy and non-waxy black rice (Oryza sativa L.) bran via widely targeted metabolomics.

Black rice (Oryza sativa L.), valued for its nutritional benefits, was investigated to elucidate metabolite profiles and antioxidant capacity differences between waxy and non-waxy varieties. Eight black rice varieties sourced from diverse Chinese provinces were categorized based on amylose content. Non-waxy varieties demonstrated significantly superior antioxidant capacity, evidenced by elevated levels of DPPH and ABTS radical-scavenging activities, FRAP values, total polyphenol content, and α-glucosidase inhibitory activity. Utilizing UPLC-MS/MS, a total of 1130 secondary metabolites were identified, with flavonoids and phenolic acids constituting prominent classes. Multivariate analysis revealed distinct metabolite profile differences between the waxy and non-waxy groups, particularly in associated metabolic and genetic pathways. The enhanced antioxidant capacity and α-glucosidase inhibitory activity were strongly associated with differential metabolites, notably flavonoids. These findings underscore the potential of non-waxy black rice bran components, particularly flavonoid-rich fractions, for development in functional food applications. .