Collagen was extracted from bigeye tuna (Thunnus obesus) skins by salting-out (PSC-SO) and isoelectric precipitation (PSC-IP) methods. The yield of the PSC-IP product was approximately 17.17% (dry weight), which was greater than the yield obtained from PSC-SO (14.14% dry weight). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that collagen from bigeye tuna skin belongs to collagen type I. Inductively coupled plasma mass spectrometry results indicate that the heavy metal abundance in PSC-IP was lower than the maximum acceptable amounts according to Chinese regulatory standards. In addition, results from a methylthiazolyldiphenyl-tetrazolium bromide assay and an in vitro scratch assay demonstrated that PSC-IP could promote the proliferation and migration of NIH-3T3 fibroblasts. Overall, results suggest PSC-IP could be used to rapidly extract collagen from marine by-products instead of traditional salting-out methods. Collagen from bigeye tuna skin may also have strong potential for cosmetic and biomedical applications.

Our study aimed to investigate the immune-enhancing mechanism of the pentadecapeptide (RVAPEEHPVEGRYLV) from Cyclina sinensis (SCSP) in a cyclophosphamide (CTX)-induced murine model of immunosuppression. Our results showed that SCSP treatment significantly increased mouse body weight, immune organ indices, and the production of serum IL-6, IL-1β, and tumor necrosis factor (TNF)-α in CTX-treated mice. In addition, SCSP treatment enhanced the proliferation of splenic lymphocytes and peritoneal macrophages, as well as phagocytosis of the latter in a dose-dependent manner. Moreover, SCSP elevated the phosphorylation levels of p38, ERK, JNK, PI3K and Akt, and up-regulated IKKα, IKKβ, p50 NF-κB and p65 NF-κB protein levels, while down-regulating IκBα protein levels. Our results indicate that SCSP has immune-enhancing activities, and that it can activate the MAPK/NF-κB and PI3K/Akt pathways to enhance immunity in CTX-induced immunosuppressed mice.

Pentachlorophenol (PCP) has attracted wide attention due to its high toxicity, persistence, and bioaccumulation. In this study, a sensitive UPLC-MS/MS method for the determination of PCP in seafood samples was developed and validated. The samples were ultrasonic extracted with acetonitrile containing 1% acetic acid-acetonitrile and followed by using a pass-through solid-phase extraction (SPE) cleanup on Captiva EMR-Lipid cartridges. The linearity of this method ranged from 1 to 1000 μg/L, with regression coefficients of >0.99. The detection limit and quantitation limit were 0.5 μg/kg and 1.0 μg/kg, respectively. The recoveries in different types of seafood samples ranged from 86.4% to 102.5%, and the intra-day and inter-day relative standard deviations (RSDs) were 3.7% to 11.2% and 2.9% to 12.1%, respectively (n = 6). Finally, the method has been successfully utilized for the screening of PCP in 760 seafood samples from Zhejiang Province. PCP was detected in 5.8% of all seafood samples, with the largest portion of detections found in shellfish, accounting for approximately 60% of the total. The average concentrations detected ranged from 1.08 to 21.49 μg/kg. The non-carcinogenic risk indices for adults and children who consume PCP ranged from 10⁻⁴ to 10⁻³ magnitudes. All of these indices stayed significantly below 1, implying that the health risk from PCP in marine organisms to humans is minimal.

Objectives: The purpose of this study was to investigate the protective effects and underlying mechanisms of fucoidan on contrast-induced acute kidney injury (CI-AKI) in mice, focusing on the TLR4/NF-κB and Nrf2/GPX4 pathways. Methods: Five-week-old male ICR mice were randomly divided into normal control, contrast model, low-dose (100 mg/kg), and high-dose (300 mg/kg) fucoidan groups. Renal index, biochemical markers, histopathology, oxidative stress indicators, inflammatory cytokine levels, and the expression of TLR4/NF-κB, Nrf2/HO-1, and ferroptosis-related proteins were assessed. Untargeted metabolomics followed by KEGG pathway enrichment was also performed. Results: Our results showed that contrast successfully established the CI-AKI model, as evidenced by an increased kidney index, abnormal biochemical parameters, severe renal pathological damage, oxidative stress imbalance, inflammatory activation, ferroptosis, and metabolic disturbances. Fucoidan dose-dependently improved kidney index and biochemical markers, alleviated pathological injury, enhanced antioxidant capacity, suppressed inflammation and ferroptosis, and reversed metabolic pathway disorders (e.g., purine and glycerophospholipid metabolism), with the high dose showing more pronounced effects. Conclusions: Fucoidan could effectively ameliorate CI-AKI, and its effects are closely associated with the inhibition of the TLR4/NF-κB pathway, activation of the Nrf2/HO-1 pathway, regulation of ferroptosis-related proteins, and improvement of key metabolic disturbances, suggesting a new research direction for the prevention of CI-AKI.