Synthetic and Natural Peptides as Antithrombotic Agents—A View on the Current Development

Roles of a protease from Euphorbia resinifera latex in human anticoagulant and antithrombotic activities

Thromboembolism is a major cause of morbidity and mortality worldwide. Most therapeutic drugs for treating thrombosis can cause hemorrhage and have short half-lives within human blood circulation resulting in a need to discover and develop novel anticoagulants/antithrombotics. EuRP-61 has been isolated from a plant latex (Euphorbia resinifera) and characterized as a serine protease. In this study, EuRP-61 was able to hydrolyze all chains of human fibrin clots. The enzyme may have long term stability in blood circulation as its fibrinogenolytic activity was not affected by human blood circulating inhibitors such as α₂-macroglobulin and antithrombin III. The enzyme may affect the extrinsic, intrinsic or common pathways of the human blood coagulation cascade as evidenced by its prolonged of both prothrombin (PT) and activated partial thromboplastin (APTT) time. Moreover, the enzyme inhibited platelet aggregation via the ADP-receptor pathway. EuRP-61 was not toxic to human red blood cells in the 4 common blood groups (A, B, O and AB) (all Rh⁺) or human peripheral blood mononuclear cells (hPBMCs). The enzyme may protect human peripheral blood cells from aggregation without destroying them. This study provides evidence that EuRP-61 may have potential as an agent for the treatment of thrombosis.

Food-derived antithrombotic peptides: Preparation, identification, and interactions with thrombin

Thromboembolism and its sequelae have been the leading causes of morbidity and mortality throughout the world. Food-derived antithrombotic peptides, as potential ingredients in health-promoting functional foods targeting thrombus, have attracted increasing attention because of their high biological activities, low toxicity, and ease of metabolism in the human body. This review presents the conventional workflow of preparation, isolation and identification of antithrombotic peptides from various kinds of food materials. More importantly, to analyze the antithrombotic effects and mechanism of antithrombotic peptides, methods for interaction of anticoagulant peptides and thrombin, the main participant in thrombosis, were analyzed from biochemistry, solution chemistry and crystal chemistry. The present study is intended to highlight the recent advances in research of food-derived antithrombotic peptide as a novel vehicle in the field of food science and nutrition. Future outlooks are highlighted with the aim to suggest a research line to be followed in further studies with the introduced research approach.

Enzymatic and chemical synthesis of new anticoagulant peptides

In this study we report the enzymatic synthesis of N-α-[Carbobenzyloxy]-Tyr-Gln-Gln (Z-YQQ), a new anticoagulant tripeptide. It was obtained using phytoproteases from the stems and petioles of Asclepias curassavica L. as catalyst in an aqueous-organic biphasic system formed by 50% (v/v) ethyl acetate and 0.1 M Tris-HCl buffer pH 8. The resulting peptide was compared with the analogous peptide Tyr-Gln-Gln (YQQ) produced by solid-phase chemical synthesis. The in vitro anticoagulant activity of the aforementioned peptides was determined using Wiener Lab Test (Wiener, Argentina). The toxicological activity of the peptides was also determined. The enzymatically synthesized Z-YQQ peptide acted on the extrinsic pathway of the coagulation cascade, delaying the conversion time of prothrombin to thrombin and fibrinogen to fibrin by 136 and 50%, respectively, with respect to the controls. The chemically synthesized YQQ peptide acted specifically on the intrinsic pathway of the coagulation cascade, affecting factors VIII, IX, XI, and XII from such cascade, and increasing the coagulation time by 105% with respect to the control. The results suggest that two new anticoagulant peptides (Z-YQQ and YQQ) can be useful for safe pharmaceutical applications. Nevertheless, some aspects related to peptide production should be optimized. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1093-1101, 2018.

Antithrombotic and Antioxidant Activity of Amaranth Hydrolysate Obtained by Activation of an Endogenous Protease

Ingestion of diets with antithrombotic and antioxidant components offer a convenient and effective way to prevent and reduce the incidence of cardiovascular diseases. The aim of the present work was to obtain an amaranth hydrolysate by the activation of an endogenous aspartic protease, to establish adequate experimental conditions, and to evaluate its antithrombotic and antioxidant activity in order to assess its potential application as an ingredient in functional foods. The results obtained not only confirmed the presence of an endogenous protease in the amaranth isolate, but also allowed us to select an adequate incubation conditions (pH 2, 40 °C, 16 h). The hydrolysate obtained (degree of hydrolysis 5.3 ± 0.4 %) showed potential antithrombotic activity (IC50 = 5.9 ± 0.1 mg soluble protein/mL) and had more antioxidant activity than the isolate, indicating that the activation of the protease released bioactive peptides from amaranth proteins. Decreasing the pH is a simple and cheap process and is another way to obtain potential functional ingredients with bioactive compounds.

Isolation and sequence determination of tetrapeptide from Selaginella bryopteris

A simple and inexpensive paper chromatographic method was developed for the isolation of a small peptide from Selaginella bryopteris fronds. The content of peptides is low in most plants and the isolation and purification procedure is troublesome. This method may be used as a first step for the detection of small peptides in the plant extracts. De novo sequence determination by tandem mass spectrometry indicated that the peptide is a tetrapeptide.

Manufacturing of peptides exhibiting biological activity

Numerous studies have shown that food proteins may be a source of bioactive peptides. Those peptides are encrypted in the protein sequence. They stay inactive within the parental protein until release by proteolytic enzymes (Mine and Kovacs-Nolan in Worlds Poult Sci J 62(1):87-95, 2006; Hartman and Miesel in Curr Opin Biotechnol 18:163-169, 2007). Once released the bioactive peptides exhibit several biofunctionalities and may serve therapeutic roles in body systems. Opioid peptides, peptides lowering high blood pressure, inhibiting platelet aggregation as well as being carriers of metal ions and peptides with immunostimulatory, antimicrobial and antioxidant activities have been described (Hartman and Miesel in Curr Opin Biotechnol 18:163-169, 2007). The biofunctional abilities of the peptides have therefore aroused a lot of scientific, technological and consumer interest with respect to the role of dietary proteins in controlling and influencing health (Möller et al. in Eur J Nutr 47(4):171-182, 2008). Biopeptides may find wide application in food production, the cosmetics industry as well as in the prevention and treatment of various medical conditions. They are manufactured by chemical and biotechnological methods (Marx in Chem Eng News 83(11):17-24. 2005; Hancock and Sahl in Nat Biotechnol 24(12):1551-1557, 2006). Depending on specific needs (food or pharmaceutical industry) different degrees of peptide purifications are required. This paper discusses the practicability of manufacturing bioactive peptides, especially from food proteins.