Wenting Jiang

Phycobiliproteins from the red alga Porphyra umbilicalis are rich precursors of bioactive peptides, but targeted identification of high-potency sequences remains challenging. To address this, we combined an in silico screening pipeline with experimental validation to discover novel antioxidant peptides. Virtual enzymatic hydrolysis generated 908 candidate sequences, which were filtered down to 12 peptides based on molecular weight, toxicity, hydrophilicity, and bioactivity predictions. Molecular docking and molecular dynamics simulations further identified four candidate peptides (FK, FKP, FRS, and RRF) that were computationally predicted to bind stably within the KEAP1 Kelch domain. Chemical assays confirmed that all four synthesized peptides exhibited dose-dependent DPPH and ABTS radical-scavenging activities, along with Fe²⁺-chelating capacity and ferric reducing antioxidant power. In H₂O₂-stimulated Caco-2 cells, peptide pretreatment protected against cellular oxidative stress by restoring endogenous antioxidant enzyme activities, increasing total antioxidant capacity, and reducing lactate dehydrogenase leakage. Among these, RRF displayed the strongest protective efficacy. Overall, this study presents a practical workflow for mining marine-derived peptides and highlights four candidate peptides whose potential as functional food ingredients warrants further validation in actual P. umbilicalis hydrolysates.

Cell cryopreservation is essential for food biotechnology and cell-based bioprocessing. However, the widely used cryoprotectant dimethyl sulfoxide (DMSO) shows dose-dependent cytotoxicity, motivating safer alternatives. Here, food-derived antifreeze peptides isolated from Takifugu obscurus skin (TsAFP) were evaluated as primary cryoprotectants using stem cells as a representative cellular model. At 15 mg/mL, TsAFP achieved a 70% replacement of DMSO while maintaining post-thaw cell growth, metabolic activity, adhesion, and multilineage differentiation. TsAFP increased solution viscosity and reduced water activity, effectively inhibiting ice growth and recrystallization. It also adsorbed onto cell membranes to form a protective interfacial layer. Molecular dynamics simulations revealed that TsAFP disrupted water ordering through stable hydrogen-bond interactions. Together, TsAFP provides extracellular and interfacial protection, while low-dose DMSO contributes intracellular protection, resulting in coordinated cryoprotection. TsAFP offers a safer, food-derived strategy to reduce DMSO reliance.

Traditional cryoprotectants such as sucrose and phosphates are limited by safety and flavor concerns, creating a demand for food-grade alternatives. Here, Bos taurus domesticus gelatin antifreeze peptides (BtAFP) were investigated for their dual cryoprotective mechanisms. Rheological analysis showed that BtAFP enhanced gel elasticity and delayed freezing, exhibiting superior cryoprotection compared with bovine serum albumin. LC-MS/MS identified 452 peptides, from which five nontoxic collagen-derived candidates with amphiphilic α-helix/β-sheet motifs were selected. Ice recrystallization assays showed that the majority of ice crystals in purified peptide solutions were concentrated below 1000 μm². Differential scanning calorimetry indicated that GKEAFP, GLPAFP, and GLRAFP most effectively inhibited ice growth. Molecular docking demonstrated stable peptide-ice and peptide-α-lactalbumin interactions, with GLPAFP notably stabilizing protein structures through extensive hydrogen bonding and surface interactions. These findings suggest that gelatin-derived antifreeze peptides suppress ice recrystallization and stabilize proteins via amphiphilic ice-binding motifs, providing promising natural cryoprotectants for frozen food applications.

This study aims to explore the cryoprotective mechanisms of food-derived hydrolyzed peptides and develop novel cryoprotectants to enhance the quality of frozen foods. Evynnis japonica scale antifreeze peptides (Ej-AFP) were prepared using enzymatic hydrolysis, which had a 4-fold increase in protection efficiency for surimi compared to traditional cryoprotectants. Furthermore, Ej-AFP was able to control 63.60% of the ice crystals to sizes below 600 μm². Three antifreeze peptide sequences were purified by using ice-affinity techniques and peptidomics. These sequences demonstrated a 21.75% enhancement in antifreeze activity and an increase of 1 °C in thermal hysteresis activity compared to Ej-AFP. Molecular simulation-elucidated ice-binding surface interacts with ice crystals through hydrogen bonds, while the nonice-binding surface disrupts the orderly arrangement of water molecules. This results in a tightly structured hydration layer around the peptide, increasing the curvature of the ice crystal surface and thereby demonstrating significant antifreeze activity in controlling ice crystal growth.