Uncovering phenolic profiles of different forms in safflower seeds and their antioxidant capacity, and biological activity

In this study, free, soluble bound (glycosylated, esterified), and insoluble-bound phenolic compounds from safflower seeds were identified and quantified by UPLC-MS/MS. The four phenolic fractions were assessed for their antioxidant capacity and inhibition of alpha-amylase and tyrosinase. In four phenolic fractions, 55 phenolic compounds, mainly flavonoids (19) and phenolic acids (16), were identified. Caffeoylserotonin was found in safflower seeds for the first time. Determination of total phenolic content showed that phenolic compounds in safflower seeds mainly existed in free form (370.16 mg GAE/100 g). The free fraction had the highest antioxidant capacity. Glycosylated fraction had the highest capacity to inhibit alpha-amylase and tyrosinase. The content of phenolic compounds exhibited a significant (p < 0.05) positive correlation with antioxidant capacity. The results of this study have improved the current knowledge of the chemical characteristics of phenolic compounds in safflower seeds and may promote the utilization of safflower seeds as a functional food.