Ferritin has good thermal stability, resistance to certain acids and bases, and targeting, and has broad application prospects in the synthesis of gold nanostars (AuNS). In this study, we screened monodisperse AuNS with uniform particle size and morphology through a one-step synthesis method and coupled the synthesized AuNS with oyster ferritin (GF1). The results showed that the surface plasmon resonance (SPR) peaks of the coupled GF1@AuNS changed significantly, and the changes in infrared spectra and potential confirmed the success of the synthesis, while the microscopic morphology showed an increase in particle size and surface peak coverage. Furthermore, GF1@AuNS does not induce cell death in the 100 μmol/L range, is highly stable in physiological environments, and exhibits good X-ray attenuation in micro-computed tomography. Due to the unique functional activity of ferritin and AuNS, GF1@AuNS has potential applications in food detection and drug development in the future.

Aging is a physiological process that leads to degeneration and functional decline of the brain. This is accompanied by intracellular peroxidation and neuronal apoptosis. Natural antioxidants possess a remarkable effect on attenuating the oxidative stress cascade and apoptosis of neurons; however, the challenge of using natural antioxidants for neuroprotection is fabricating a delivery system to overcome the blood-brain barrier (BBB) transport. Herein, we successfully created a stable delivery platform built on rigid ferritin nanocage loading natural lycopene (LYC) molecules, crossing the BBB in quantity and being taken up in neurons. This nanoparticle worked on D-galactose-induced senescence via alleviating neuronal hyperoxidation injury and weakening neuronal apoptosis in PC12 and BV2 cells. More importantly, this natural delivery system possesses inherent biocompatibility and potential application in improving the bioavailability of bioactive edible compounds with low water solubility. This study demonstrated the effectiveness of natural antioxidant nanomedicines in maintaining the defenses of intracerebral peroxidation and improve degenerating neurons, providing the potential to combat further imbalances of neuronal microenvironment in aging neuropathy.

Oyster (Crassostrea gigas), the main ingredient of oyster sauce, has a strong umami taste. In this study, three potential umami peptides, FLNQDEEAR (FR-9), FNKEE (FE-5), and EEFLK (EK-5), were identified and screened from the alcoholic extracts of the oyster using nano-HPLC-MS/MS analysis, iUmami-Scoring Card Method (iUmami-SCM) database and molecular docking (MD). Sensory evaluation and electronic tongue analysis were further used to confirm their tastes. The threshold of the three peptides ranged from 0.38 to 0.55 mg/mL. MD with umami receptors T1R1/T1R3 indicated that the electrostatic interaction and hydrogen bond interaction were the main forces involved. Besides, the Phe592 and Gln853 of T1R3 were the primary docking site for MD and played an important role in umami intensity. Peptides with two Glu residues at the terminus had stronger umami, especially at the C-terminus. These results contribute to the understanding of umami peptides in oysters and the interaction mechanism between umami peptides and umami receptors.

Oysters (Crassostrea gigas) have a wide range of functionality due to their nutritional and bioactive components. However, the bioactive peptides of oyster proteins are rarely reported, particularly their anti-diabetes effects and antioxidants. Oyster proteins were extracted from fresh oysters using phosphate-buffered saline and simulated gastrointestinal digestion was performed. The degree of hydrolysis (DH), structural characterization, molecular weight (Mw) distribution, free amino acid, anti-diabetic activity, and antioxidant activity were studied during in vitro simulated gastrointestinal digestion. The results showed that the α-glucosidase inhibitory activity, α-amylase inhibitory activity, DPPH radical scavenging activity, and ABTS radical scavenging activity of the oyster protein gastrointestinal digest were increased (P < 0.05) from 0 to 33.96 %, from 9.17 % to 44.22 %, from 9.01 µg trolox/mg protein to 18.48 µg trolox/mg protein, and from 21.44 µg trolox/mg protein to 56.21 µg trolox/mg protein, respectively. Additionally, the DH, β-turn structure, fluorescence intensity, free amino acid, and short peptide content (Mw < 1000 Da) increased in the simulated gastrointestinal digestion. These results indicate that the digestive hydrolysates obtained from oyster proteins could be used as natural anti-diabetic and antioxidant agents.

There are many active substances in Atlantic cod (Gadus morhua) explaining the variety of biological activities. In order to study the immunomodulatory activity and the mechanism of Atlantic cod peptides at the cellular level. In this study, cod peptides were isolated by 80 % ethanol extraction method, the isolated ethanol-soluble cod peptides (CP-ES) were investigated and their immunomodulatory activity was verified. Additionally, CP-ES showed lower molecular weight and more hydrophobic amino acids. CP-ES could promote the proliferation of spleen lymphocytes and T lymphocytes in mice, suggesting that CP-ES may regulate adaptive immunity. It promoted the release of NO and the expression of iNOS, TNF-α, IL-6 and IL-1β genes in macrophages, suggesting that CP-ES may regulate innate immunity. CP-ES could promote the expression of TLR2 gene, and the peptides identified in CP-ES were docked with TLR2 to predict the peptides playing a major role in CP-ES. These results suggested that CP-ES may regulate the immune activity of both innate and adaptive lines.

There is no study on food-derived peptide with both anticoagulant and angiotensin I-converting enzyme inhibitory (ACEI) activities yet. In this work, the anticoagulant and ACEI activities of the casein hydrolysates released by pepsin digestion were evaluated for the first time to the best of our knowledge. Results indicated that the casein hydrolysate exhibited potent anticoagulant activity by prolonging the thrombin time (TT) and the activated partial thromboplastin time (APTT). Compared with control samples, at 10 mg/mL, the TT and APTT of casein hydrolysate were 186.0 % ± 6.6 % and 163.5 % ± 7.4 %, respectively. The casein hydrolysate also showed a strong ACEI activity with an IC₅₀ value of 1.775 mg/mL. The components of the bioactive casein hydrolysate were analyzed by nanoscale liquid chromatography quadrupole time-of-flight tandem mass spectrometry (NanoLC-Q-TOF-MS/MS). Total of 115 peptides were identified, among which 34, 9, 55 and 17 peptides were derived from α_s1-, α_s2-, β-, and κ-casein, respectively. The results of PeptideRanker and PepSite 2 analysis showed that 6 peptides (FRQFYQL, NENLLRF, NPWDQVKR, PVVVPPFLQ, PVRGPFPIIV, and ARHPHPHLSF) have both ACEI and anticoagulant activities by binding to the active sites of ACE and thrombin. This study indicated that casein is a potential functional food supplement that can be used for medical purposes.

Owing to the formation of aggregation and gelation during storage, certain proteins and peptides exhibit limited applications in aqueous protein food products. The purpose of this study was to investigate the influence of homogenization and xanthan gum addition on the dispersion stability of Mytilus edulis hydrolysate (PHM). High-pressure homogenization (HPH) at 360 and 40 bar in the first and second values, respectively, and adding xanthan gum at a concentration of 1 mg/mL showed significantly improvement on the stability of the PHM solution. PHM-xanthan gum solutions (PHMX) showed the highest polypeptide precipitation rate and turbidity retention rate compared with those of PHM. Moreover, the centrifugal precipitation rate of PHMX without HPH was higher than that of homogeneous PHMX. After HPH treatment at 400 bar, the percentage of smaller particles in PHM and PHMX was increased, the aqueous system became more uniform, and the fluorescence intensity reached its maximum. HPH pre-treatment improved the polypeptide dispersion stability and turbidity retention rate of PHM and PHMX and reduced the fluorescence intensity. The interactions of xanthan gum and polypeptide render the network microstructure more uniform under the conditions of homogenization, thus improving the dispersion stability of PHMX solutions. Therefore, under the premise of adding xanthan gum, HPH can better enhance the dispersion stability of the polypeptide in PHM.