Hyperuricemia is linked to a variety of disorders that can have serious consequences for human health. Peptides that inhibit xanthine oxidase (XO) are expected to be a safe and effective functional ingredient for the treatment or relief of hyperuricemia. The goal of this study was to discover whether papain small yellow croaker hydrolysates (SYCHs) have potent xanthine oxidase inhibitory (XOI) activity. The results showed that compared to the XOI activity of SYCHs (IC₅₀ = 33.40 ± 0.26 mg/mL), peptides with a molecular weight (MW) of less than 3 kDa (UF-3) after ultrafiltration (UF) had stronger XOI activity, which was reduced to IC₅₀ = 25.87 ± 0.16 mg/mL (p < 0.05). Two peptides were identified from UF-3 using nano-high-performance liquid chromatography–tandem mass spectrometry. These two peptides were chemically synthesized and tested for XOI activity in vitro. Trp-Asp-Asp-Met-Glu-Lys-Ile-Trp (WDDMEKIW) (p < 0.05) had the stronger XOI activity (IC₅₀ = 3.16 ± 0.03 mM). The XOI activity IC₅₀ of the other peptide, Ala-Pro-Pro-Glu-Arg-Lys-Tyr-Ser-Val-Trp (APPERKYSVW), was 5.86 ± 0.02 mM. According to amino acid sequence results, the peptides contained at least 50% hydrophobic amino acids, which might be responsible for reducing xanthine oxidase (XO) catalytic activity. Furthermore, the inhibition of the peptides (WDDMEKIW and APPERKYSVW) against XO may depend on their binding to the XO active site. According to molecular docking, certain peptides made from small yellow croaker proteins were able to bind to the XO active site through hydrogen bonds and hydrophobic interactions. The results of this work illuminate SYCHs as a promising functional candidate for the prevention of hyperuricemia.

Hyperuricemia arises from imbalanced uric acid metabolism, contributing to gout and related chronic diseases. When traditional drugs are used to treat hyperuricemia, side effects are inevitable, which promotes the exploration of new bioactive compounds. Protein hydrolysates and peptides are gradually showing potential in the treatment of hyperuricemia. This study investigated the uric acid inhibitory activity of peptides extracted from Trachurus japonicus using in silico and in vitro methods. We employed in silico virtual enzymolysis and experimental validation to identify bioactive peptides from Trachurus japonicus proteins. Four peptides (DF, AGF, QPSF, and AGDDAPR) were comprehensively screened by molecular docking and database analysis. After solid-phase synthesis, the inhibitory effects of these peptides on hyperuricemia were further verified in vitro and at the cellular level. The results showed that all four peptides have good hyperuricemia-inhibiting activities. Molecular docking and molecular dynamics revealed that peptides DF and AGDDAPR affect the production of uric acid by binding to the active sites of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), and xanthine oxidase (XOD), while peptides QPSF and AGF mainly influence the XOD active site, confirming that it is feasible to rapidly screen hyperuricemia-inhibiting peptides by molecular docking.

The effects of zein coating on the total bacterial count, total volatile base nitrogen and histamine in high (5.0 log CFU/g) and low (2.0 log CFU/g) spiked roasted rabbit legs stored at different temperature (−20, 4, 20, and 37 °C) were studied. At 37 °C, the preservation effect of zein film was not obvious. If storage temperature was below 37 °C, zein coating inhibited microbial breeding and histamine production significantly. Freezing (−20 °C) is an effective way to inhibit the growth of microorganisms and histamine accumulation. However, microbes breed rapidly when samples defrosted at 20 °C. Compared to samples without coating, samples coated zein can store for 48 h at room temperature, and the total volatile base nitrogen is still below the threshold (< 30 mg/100 g). These results can provide a reference for the production of high quality meat related products with zein coating.