Enrichment and purification of Torreya grandis peptides by macroporous resin and its hypoglycemic mechanism revealed by transcriptome analysis

The objective of this study was to develop an efficient strategy to prepare high-hypoglycemic efficacy Torreya grandis meal peptides with macroporous resin and investigate the underlying mechanisms through transcriptome analysis. The evaluation of adsorption and desorption abilities of Torreya grandis meal peptides (TGPs) on six different microporous resins were compared. The hypoglycemic activity of prepared TGPs was further measured in a Zebrafish diabetic model, and the underlying mechanisms were investigated through transcriptome analysis. Results showed that DA201-C exhibited the highest adsorption and desorption capacities. After DA201-C resin enrichment, the α-glucosidase inhibition and α-amylase inhibition activities of TGPs in 75% ethanol eluate (TGPs-75) both significantly increased (the IC50 values are 0.41 mg/mL and 1.08 mg/mL, respectively). The in vivo data showed that TGPs-75 remarkably reduced blood glucose concentrations to 7.8, 15.6, and 31.2 μg/mL in an high-sugar-high-fat-treated (HSHF-treated) Zebrafish diabetic model and exerted obvious hypoglycemic activity. According to transcriptome analysis, 382 genes were significantly differentially expressed (229 up-regulated and 153 down-regulated) after TGPs-75 pretreatment. The main functions of these genes are related to gluconeogenesis and insulin resistance. The findings from the present study suggested that TGPs-75 produced positive hypoglycemic efficacy and showed potential to provide a scientific basis for its further utilization as a dietary supplement or an ingredient in functional foods.