Therapeutic effects and mechanisms of N-(9,10-anthraquinone-2-ylcarbonyl) xanthine oxidase inhibitors on hyperuricemia.

Objective: To observe the antioxidative effects of N-(9,10-anthraquinone-2-ylcarbonyl) xanthine oxidase inhibitors (NAY) in vitro and in vivo models of hyperuricemia and explore the mechanism. Methods: A classical experimental method of acute toxicity and a chronic toxicity test were used to compare the toxic effects of different doses of NAY in mice. The hyperuricemia mouse model was established by gavage of potassium oxonate in vivo. After treatment with different doses of NAY (low dose: 10 mg/kg, medium dose: 20 mg/kg, and high dose: 40 mg/kg) and allopurinol (positive drug, 10 mg/kg), observe the levels of uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) in urine and serum, respectively, and detect the activities of xanthine oxidase in the liver. The hyperuricemia cell model was induced by adenosine and xanthine oxidase in vitro. The cells were given different doses of NAY (50, 100, and 200 µmol/L) and allopurinol (100 µmol/L). Then the culture supernatant UA level of the medium was measured. The next step was to detect the xanthine oxidase activity in the liver and AML12 cells, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammatory factors in the kidney and serum of mice. Western blot was used to detect xanthine oxidase protein expression in mouse liver tissue and AML12 cells, ASC, Caspase-1, NLRP3, GLUT9, OAT1, and OAT3 protein expression in mouse kidney tissue and HK-2 cells. Hematoxylin-eosin staining was used to stain the liver and kidney tissues of mice and observe the tissue lesions. Results: NAY had little effect on blood routine and biochemical indexes of mice, but significantly reduced the serum UA level. NAY significantly reduced the level of UA in hyperuricemia mice and cells by inhibiting xanthine oxidase activity and reduced the levels of TNF-α, IL-6, and other inflammatory factors in serum and kidney of mice. NAY can inhibit inflammation by inhibiting the NLRP3 pathway. In addition, NAY can downregulate GLUT9 protein expression and upregulate OAT1 and OAT3 protein expression to reduce the UA level by promoting UA excretion and inhibiting UA reabsorption. Conclusion: These findings suggested that NAY produced dual hypouricemic actions. On the one hand, it can inhibit the formation of UA by inhibiting xanthine oxidase inhibitors activity, and on the other hand, it can promote the excretion of UA by regulating the UA transporter. It provides new ideas for the development of hyperuricemia drugs in the future.

Effect of a Sodium Alginate Coating Infused with Tea Polyphenols on the Quality of Fresh Japanese Sea Bass (Lateolabrax japonicas) Fillets.

Sodium alginate (SA) and tea polyphenols (TP) are natural preservatives commonly used in the food industry, including the production of fish products. The effect of SA coating infused with TP on the quality of fresh Japanese sea bass (Lateolabrax japonicas) fillets was evaluated over a 20-day period at 4 °C. SA (1.5%, w/v) or TP (0.5%, w/v) treatment alone, and the SA coating infused with TP (SA-TP) all reduced microbial counts, with the SA-TP providing the greatest effect. Fish fillet samples treated with SA-TP had significantly lower levels of total volatile basic nitrogen, lipid oxidation, and protein decomposition during the storage period, relative to the remaining treatments. The samples treated with SA-TP had the highest sensory quality rating as well. Collectively, sodium alginate coating infused with tea polyphenols may represent a promising treatment for preservation of Japanese sea bass fillets during cold storage. PRACTICAL APPLICATION: The sodium alginate-tea polyphenols composite coating has strong potential to be used as a new biopreservative for maintaining fish fillet quality.

GlyT1 Inhibitor NFPS Exerts Neuroprotection via GlyR Alpha1 Subunit in the Rat Model of Transient Focal Cerebral Ischaemia and Reperfusion.

BACKGROUND/AIMS: Glycine is a strychnine-sensitive inhibitory neurotransmitter in the central nervous system (CNS), especially in the spinal cord, brainstem, and retina. The objective of the present study was to investigate the potential neuroprotective effects of GlyT1 inhibitor N [3-(4'-fluorophenyl)-3-(4'-phenylphenoxy) propyl] sarcosine (NFPS) in the rat model of experimental stroke. METHODS: In vivo ischaemia was induced by transient middle cerebral artery occlusion (tMCAO). The methods of Western Blotting, Nissl Staining and Morris water maze methods were applied to analyze the anti-ischaemia mechanism. RESULTS: The results showed that high dose of NFPS (H-NFPS) significantly reduced infarct volume, neuronal injury and the expression of cleaved caspase-3, enhanced Bcl-2/Bax, and improved spatial learning deficits which were administered three hours after transient middle cerebral artery occlusion (tMCAO) induction in rats, while, low dose of NFPS (L-NFPS) exacerbated the injury of ischaemia. These findings suggested that low and high dose of NFPS produced opposite effects. Importantly, it was demonstrated that H-NFPS-dependent neuronal protection was inverted by salicylate (Sal), a specific GlyR x0251;1 antagonist. Such effects could probably be attributed to the enhanced glycine level in both synaptic and extrasynaptic clefts and the subsequently altered extrasynaptic GlyRs and their subtypes. CONCLUSIONS: These data imply that GlyT1 inhibitor NFPS may be a novel target for clinical treatment of transient focal cerebral ischaemia and reperfusion which are associated with altered GlyR alpha 1 subunits.

Glycine bidirectionally regulates ischemic tolerance via different mechanisms including NR2A-dependent CREB phosphorylation.

The exact effect of glycine pre-treatment on brain ischemic tolerance (IT) remains quite controversial. The objective of this study was to investigate the potential effects of glycine on IT. We used rat models of both in vitro ischemia (oxygen and glucose deprivation) and in vivo ischemia (transient middle cerebral artery occlusion). Low doses of glycine (L-Gly) significantly decreased hippocampal ischemic LTP (i-LTP), infarct volume, and neurological deficit scores which were administered before ischemia was induced in rats, whereas high doses of glycine exerted deteriorative effects under the same condition. These findings suggested that exogenous glycine may induce IT in a dose-dependent manner. Furthermore, L-Gly-dependent neuronal protection was inversed by L689, a selective NMDAR glycine site antagonist both in vitro (abolished i-LTP depression) and in vivo (increased infarct size reduction), but not glycine receptor (GlyR) inhibitor strychnine. Importantly, L-Gly-induced IT was achieved by NR2A-dependent cAMP-response element binding protein phosphorylation. These data imply that glycine pre-treatment may represent a novel strategy for inducing IT based on synaptic NMDAR-dependent neuronal transmission. A model of glycine induced dose-dependent bidirectional regulations in ischemic tolerance. (a) Under low dose of Gly pre-treatment, glycine induces NMDAR potentiation and CREB-dependent neuroprotection through the NMDAR co-agonist binding site. (b) Under high dose of Gly pre-treatment, the excessive glycine in synaptic cleft can activate neighboring extrasynaptic sites and combine to the GlyRs. Then, the deteriorative effects would be triggered after NMDAR endocytosis and synaptic depression. AMPAR, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor; CREB, cAMP response element-binding protein; Gly, glycine; GlyR, glycine receptor; GlyT1, gycine transportor 1; NMDAR, N-methyl-d-aspartate receptor.