Serum proteomic analysis reveals possible mechanism underlying physiological hemostasis of swim bladder

Dual function antioxidant and anti-inflammatory fish maw peptides: Isolation and structure-activity analysis via tandem molecular docking and quantum chemical calculation

The structure-function relationship of gastrointestinal tract digestion-derived fish maw peptides remains largely unknown. This study aims to elucidate the active sites and cellular bioactivities of these peptides through molecular docking (MD), density functional theory (DFT) computations, in silico bioinformatic analysis, and in cellulo Caco-2 cell studies. In silico screening identified 29 non-toxic, non-allergenic, and water-soluble peptides. Seven peptides exhibited favorable binding to the Keap1-Kelch (2FLU) and TNF-α (2AZ5) proteins. Specifically, peptides WIDPNQG, GFPGER, and FLLFRQ demonstrated the highest electron affinities and smallest HOMO-LUMO energy gaps, suggesting strong free-radical scavenging potential. Both DFT and ex situ MD confirmed the active sites of the seven peptides. The guanidinium group was the dominant active site on six peptides. The isolated peptides improved cellular redox balance, reduced malonaldehyde, and suppressed inflammatory cytokines. This study confirmed DFT computations as a novel tool for elucidating the structure-function relationship of food-derived peptides.

Identification of antioxidant peptides after digestion and absorption of isinglass by serum peptidomics and cellular antioxidant activity analysis

Isinglass, a dried product of the swim bladder, has been widely used in traditional Chinese medicine. This study attempts to identify natural antioxidant peptides after digestion and absorption of isinglass in vivo. The antioxidant effects of dietary isinglass were demonstrated by evaluating the activities of SOD, CAT and MDA contents in the mouse liver. Four novel antioxidant-related peptides (RLLWENGNLL, GSKAENPTNPGP, SPVPDLVPGSF and VPDLVPGSF) were screened based on serum peptidomics and amino acid composition. Furthermore, pretreating with four peptides significantly increased the cell viability, and SOD and CAT activities of AML12 cells with H₂O₂-mediated oxidative damage, meanwhile, significantly reduced the ROS level, MDA content and apoptosis rate and attenuated DNA damage. Therefore, it was concluded that pretreatment of the identified peptides had a protective effect on oxidatively damaged cells. This result can aid in the recognition of active peptides from isinglass consumption for potential application in nutraceuticals or functional ingredients in food.

Pea Protein-Derived Peptides Inhibit Hepatic Glucose Production via the Gluconeogenic Signaling in the AML-12 Cells

Pea protein is considered to be a high quality dietary protein source, but also it is an ideal raw material for the production of bioactive peptides. Although the hypoglycemic effect of pea protein hydrolysate (PPH) has been previously reported, the underlying mechanisms, in particular its effect on the hepatic gluconeogenesis, remain to be elucidated. In the present study, we found that PPH suppressed glucose production in mouse liver cell-line AML-12 cells. Although both of the gluconeogenic and insulin signaling pathways in the AML-12 cells could be regulated by PPH, the suppression of glucose production was dependent on the inhibition of the cAMP response element-binding protein (CREB)-mediated signaling in the gluconeogenic pathway, but not the activation of insulin signaling. Findings from the present study have unveiled a novel role of PPH underlying its anti-diabetic activity, which could be helpful to accelerate the development of functional foods and nutraceuticals using PPH as a starting material.