Purification, composition and activity of bound polyphenols from mung bean coat dietary fiber

In this study, the static adsorption–desorption performance of seven macroporous resins for bound polyphenols from mung bean coat dietary fiber (MBDF-BP) was compared, and NKA-9 macroporous resin was preferably screened for subsequent separation and purification. The composition of the purified products was identified and quantified, 44 major compounds were detected, with the main phenolic acid being p-hydroxybenzoic acid, which contained up to 8881.90 μg/g DW. The purification enriched flavonoids, with high contents of catechin (1419.03 μg/g DW) and vitexin (615.88 μg/g DW). The MBDF-BP purified products (pMBDF-BP) produced significant reversible inhibitory activity against α-glucosidase in a mixed-type inhibition manner, which was superior to the reported crude extracts. The antioxidant activity assays showed that pMBDF-BP exhibited distinct scavenging effects on DPPH•, ABTS+•, •OH free radicals, as well as reactive oxygen species (ROS) in Caenorhabditis elegans (C. elegans). These results demonstrated that NKA-9 macroporous resin could effectively enrich MBDF-BP extracts and enhance its antioxidant activity, which was promising to explore new sights into the applications of bound polyphenols from mung bean coat dietary fiber in functional foods or dietary supplements, thus contributing to the scientific utilization of mung bean coat resources and increasing the added value of related products.