Gout is a recurrent inflammatory disease caused by increased metabolism of purines or abnormal uric acid excretion. Xanthine oxidase (XO) is the key enzyme that regulates the generation of uric acid during the metabolism of purines into uric acid. Its function is to convert hypoxanthine into xanthine and into uric acid. By inhibiting the activity of XO, the production of uric acid can be inhibited, thereby relieving hyperuricemia. In recent years, small molecule uric acid-lowering peptides derived from proteins have attracted the attention of researchers because of their low preparation cost, high safety, easy absorption, and high activity, stability and specificity. This paper presents an overview of XO, and summarizes the general steps for the isolation and identification of XO, summarizes recently discovered mixed and single peptide inhibitors of XO with a special reference to the structural commonness of these inhibitors. This review will hopefully provide novel ideas and directions for researchers to discover new XO inhibitory peptides.

Nattokinase (NK), a serine protease, can be used as a thrombolytic agent. Compared with clinical thrombolytic drugs (urokinase and streptokinase), NK has the advantages of low price, high thrombolytic efficiency, oral administration, and no toxic side effect, making it an ideal natural thrombolytic agent. At present, commercial thrombolytic NK products have the problems of low activity and bioavailability, which enter the bloodstream to exert thrombolytic effects through the oral and gastrointestinal digestion and absorption system. The gastrointestinal tract (GIT) environment (strong acidity, pepsin and trypsin) can destroy the spatial structure of NK, leading to a decrease or loss of its thrombolytic activity. The construction of functional vectors for NK delivery using natural biomaterials such as lipids, polysaccharides, and proteins can effectively avoid these adverse factors in the digestive system, enhancing the stability of NK, and improving its biological activity and bioavailability in the body. Beginning with an overview of the structural and functional properties of NK, this paper summarizes recent progress in research on functional vectors for NK delivery in order to provide a theoretical basis and technical support for efficient and stable thrombolytic NK products.

Thrombin blockers have been shown to be effective for various pathological conditions, but their use is limited due to the potential for serious bleeding adverse effects. This study introduced a novel bioactive peptide (P-2-CG) from oyster, that mitigated thrombin-mediated barrier dysfunction and prothrombotic phenotypes in human pulmonary microvascular endothelial cells (HPMECs). P-2-CG significantly attenuated the increase in endothelial monolayer permeability induced by thrombin through the possible attenuation of RhoA activation and it promoted barrier recovery by enhancing endothelial cell adhesion. Additionally, P-2-CG was found to decrease the pro-thrombotic phenotype induced by thrombin in HPMEC by reducing the extrinsic trigger tissue factor mRNA expression, which resulted in prolonged plasma clotting time, decreased Factor Xa activation, and reduced thrombin generation. Moreover, P-2-CG inhibited thrombosis efficiently by blocking intercellular adhesion molecule 1 and vascular cell adhesion protein 1 expression via tyrosine phosphorylation of nuclear factor-κB p65. P-2-CG inhibits thrombin mediated inflammation and provides a potential therapeutic option for treating endothelial dysfunction and thrombosis.

A comprehensive method was applied to evaluate the anticoagulant activity of a novel anticoagulant peptide (NAESLRK) derived from oyster (Crassostrea gigas). The anticoagulant peptide drastically reduced the extrinsic clotting activity and also impaired the intrinsic clotting activity slightly. Consistent with clotting data, the thrombin peak height was reduced to 84.7 nmol/L from 123.4 nmol/L, and thrombin generation time was delayed to 4.67 min from 4.42 min when the extrinsic trigger was applied. The inhibitory kinetics of FⅪa, FⅨa, FⅩa, FⅡa, and APC in a purified component system rationally explained the reduction of extrinsic clotting activity and impairment of thrombin generation. Besides the inhibition of FⅩa and FⅡa activity, the activation processes of FⅩ and FⅡ by intrinsic/extrinsic tenase complex and prothrombinase were also damaged. The anticoagulant activity in the plasma system was the result of comprehensive inhibition of various factors. The research provided a novel method for anticoagulant evaluation and inhibitory mechanism of bioactive peptides from food products.

Bone morphogenetic proteins (BMPs) are a family of potent, multifunctional growth factors belonging to transforming growth factor-β (TGF-β). They are highly conservative in structures. Over 20 members of BMPs with varying functions such as embryogenesis, skeletal formation, hematopoiesis and neurogenesis have been identified in human body. BMPs are unique growth factors that can induce the formation of bone tissue individually. BMPs can induce the differentiation of bone marrow mesenchymal stem cells into osteoblastic lineage and promote the proliferation of osteoblasts and chondrocytes. BMPs stimulate the target cells by specific membrane-bound receptors and signal transduced through mothers against decapentaplegic (Smads) and mitogen activated protein kinase (MAPK) pathways. It has been demonstrated that BMP-2, BMP-4, BMP-6, BMP-7, and BMP-9 play an important role in bone formation. This article focuses on the molecular characterization of BMPs family members, mechanism of osteogenesis promotion, related signal pathways of osteogenic function, relationships between structure and osteogenetic activity, and the interactions among family members at bone formation.