In vitro studies on a novel micelle-forming peptide with anticoagulant activity

Glyproline peptide family: review on bioactivity and possible origins

Glyproline peptide family includes the simplest proline-containing linear peptides PG, GP, PGP, respective peptides with hydroxylated proline residues and (with some restriction) cyclic PG. Having close structural resemblance they display many similar bioactivities. The suppression of some reactions of blood coagulation and platelet aggregation and protection of gastric mucosa against various ulcerogenic factors are the most important glyproline effects. Glyprolines have two common putative sources: (1) collagen and elastin synthesis and catabolism, and (2) penetration of proline-containing di- and tripeptides from food protein hydrolysate from the intestine into bloodstream. Possible physiological and biochemical mechanisms of glyproline bioactivities are under discussion.

Experimental myocardial necrosis in rats: role of arjunolic acid on platelet aggregation, coagulation and antioxidant status

Arjunolic acid, a new triterpene and a potent principle from the bark of Terminalia arjuna, has been shown to provide significant cardiac protection in isoproterenol induced myocardial necrosis in rats. To further explore the mechanism of action of arjunolic acid, antiplatelet activity, anticoagulant assays, electrocardiographic changes, serum marker enzymes, antioxidant status, lipid peroxide and myeloperoxidase (MPO) have been measured and the results are compared with a potent cardioprotective drug, acetyl salicylic acid (ASA). Administration of isoproterenol produces electrocardiographic changes such as decreased R amplitude and increased ST segment elevation and has resulted in an increase in serum marker enzyme levels as well as a decrease in enzymatic and nonenzymatic antioxidant levels. Arjunolic acid at an effective dosage of 15 mg/kg body wt. (pre and post treatment), when administered intraperitoneally (i.p.), effects a decrease in serum enzyme levels and the electrocardiographic changes get restored towards normalcy. Arjunolic acid treatment is also shown to prevent the decrease in the levels of superoxide dismutase, catalase, glutathione peroxidase, ceruloplasmin, alpha-tocopherol, reduced glutathione (GSH), ascorbic acid, lipid peroxide, MPO and the cardioprotection is confirmed by the histopathological studies. This study shows that the cardioprotection of arjunolic acid pre and post treatment could possibly be due to the protective effect against the damage caused by myocardial necrosis.

The effect of prolil-glycil-proline (PGP) peptide and PGP-rich substances on haemostatic parameters of rat blood

The effect of intravenous and intranasal administration of proline-containing peptide, especially prolil-glycil-proline (PGP), on the haemostatic system of rats was investigated. Tripeptide PGP after single intravenous (0.2, 1.0 and 1.5 mg/kg) or intranasal (0.5 mg/ kg) administration increased (P < 0.05) total fibrinolytic and fibrin depolymerizating (FDA) activities, and tissue plasminogen activator levels (t-PA), and decreased the plasmin inhibitors (PI) and activated factor XIII (factor XIIIa) levels in blood plasma. Repeated daily intranasal administration (5 days) of PGP produced a significant increase of anticoagulant and fibrinolytic activities (P < 0.05), and a decrease of platelet aggregation, PI and factor XIIIa levels in blood plasma. Fibrinogen concentrations remained practically unchanged. Chronic peroral administration of gelatin (protein particularly rich of PGP, prolil-glycil, glycil-proline) as a food supplement significantly increased t-PA level (by 120%) at day 10 and FDA (by 290%) at day 14 in blood plasma. We also observed potent suppression of thrombus formation (venous thrombosis model) by intranasal PGP administration. Therefore, PGP and some PGP-rich substances can be qualified as potent anticoagulant and antithrombotic agents.