Antiplatelet aggregation

Scientific articles short abstracts about anti Platelet Aggregating Factor  and other coagulation mechanisms are presented. A complete explanation of this very complex subject is not presented yet.

Rosarypea (Abrus precatorius) Potent antiplatelet, anti-inflammatory and antiallergic isoflavanquinones from the roots of Abrus precatorius. Abruquinones A, B and D inhibited arachidonic acid-induced platelet aggregation, with IC50 values of <5, <5 and <10 æg/ml, respectively. The same compounds and abruquinone F also exhibited strong antiinflammatory and antiallergic properties

Mountain soursop (Annona montana) Three structurally related acid amides, N-trans-feruloyltyramine, N-p-coumaroyltyramine, and N-trans-caffeoyltyramine (a new compound), a lignan, (-)-syringaresinol, an aromatic aldehyde, syringaldehyde, and 2 steroids, beta-sitosterol and beta-sitosterol-beta-D-glucoside, were isolated from the stems of A. montana, collected from Taiwan, in Dec. 1990. Their chemical structures were elucidated from spectral data. Some of the compounds and/or their acetate derivatives exhibited significant activities in the antiplatelet aggregation bioassay using rabbit blood and in cytotoxicity bioassays using 5 common cell lines (data presented).

Artemisia An Etanolic extract of Artemisiae Capillari Spica (Artemisia capillaris) inhibited both bovine lens aldose [aldehyde] reductase (bovine-LAR) and rabbit platelet aggregation. Two coumarins, scoparone and scopoletin, and 3 flavonoids, capillarisin, cirsimaritin and rhamnocitrin, were isolated from this extract. Scoparone and scopoletin exhibited a potent inhibitory effect on rabbit platelet aggregation

Professor-weed An aqueous extract of aerial parts of G. officinalis (collected from Bulgaria), administered i.v. to rats, suppressed platelet aggregation. This suppression was lost 3 h after administration of the extract.

Ginkgo (Ginkgo biloba) As previous studies have shown that EGb 761 has an antiaggregatory effect on platelets, thrombin, serotonin (platelet-derived compounds that are present in the serum) and a thromboxane analogue (U46619) were also used to induce vasospasm. Administration of EGb 761 (30 mg/kg), 5 min after exposure of the preparation to serotonin (10-3 M) or 10 min after exposure to thrombin (20 units), did not affect vasospasm induced by these agents. In contrast, treatment with this same dose of EGb 761, 5 min after exposure of the preparation to U46619 (10-4 M), abolished the arteriolar constriction induced by this agent in 15 min. The thromboxane/prostaglandin H2 receptor antagonist SQ29548 antagonized serum-induced vasospasm, indicating an involvement of thromboxane. Other experiments indicated that the effects of EGb 761 in counteracting vasospasm may be mediated in part by ginkgolide B, a triterpene constituent of the extract that is an antagonist of platelet-activating factor and in part by an ‘NO-like’ action of its proanthocyanidin constituents. Taken together, these results indicate that EGb 761 treatment can antagonize the vasoconstrictor effect of thromboxane on arterioles. As thromboxane is implicated in many cardiovascular disorders, this property of EGb 761 may explain some of its beneficial clinical effects in such pathologies.

Nutmeg Hypolipidaemic effect of Myristica fragrans fruit extract in rabbits. The extract also showed platelet anti-aggregatory ability in platelet-rich rat plasma.

Indian lotus Neferine (isolated from Nelumbo nucifera) and taurine, alone and in combination, inhibited platelet aggregation induced by ADP, collagen and thrombin

Evening Primrose (Oenothera biennis) The various constituents isolated from Oenothera species are reviewed. These include steroids, terpenoids, fatty acids, flavonoids and tannins. The following are some of the activities reported for the various parts of the plant, or for the isolated chemicals: antiasthmatic, antitumour, antiviral, fungistatic, antiarthritic and antithrombic.

Peony The pharmacological effects of water extracts of roots of Paeonia suffruticosa, P. anomala, P. lactiflora and P. lutea were investigated in rats. The extracts exhibited high anticoagulant properties and the ability to lyse nonstabilised fibrin in vitro. Peroral chronic administration of an extract of P. suffruticosa increased the fibrinolytic activity of blood and contributed to the prevention of thrombosis in vessels and helped lyse freshly formed thrombi in blood.

Piper The isolation and structural elucidation of three new neolignans, puberulins A, B, and C, as platelet activating factor receptor antagonists from Piper puberulum. Puberulins A and C inhibited the binding of platelet activating factor to its receptor sites on isolated rabbit platelet plasma membranes

Rhamnus Novel antiplatelet naphthalene from Rhamnus nakaharai   A new naphthalene derivative, isotorachrysone, and the known compounds, 6-methoxysorigenin and quercetin 3-O-methyl ether, were isolated from the stem bark of R. nakaharai (collected from Taiwan).
These antiplatelet effects are due partially to an inhibitory effect on thromboxane formation

Baikai Scullcap (Scutellaria baicalensis) Studies on the effects of flavonoids isolated from roots of S. baicalensis on the fibrinolytic system induced by trypsin in cultured human umbilical vein endothelial cells showed that baicalein strongly inhibited the reduction of tissue type plasminogen activator production and the elevation of type 1 plasminogen activator inhibitor (PAI-1) production induced by trypsin. It was suggested that baicalein prevented the thrombotic tendency induced by trypsin.

Cedar thuja Pinusolide, a potent platelet activating factor (PAF) receptor-binding antagonist isolated from the hexane and chloroform extracts of Biota orientalis [Thuja orientalis], inhibited PAF-induced aggregation of rabbit platelets (IC50 value of 5 æM), but had no inhibitory effect on ADP-, thrombin-, or collagen-induced platelet aggregation. Pinusolide also protected mice from PAF-induced lethality (ED50 values of 1.1 mg/kg, i.v., and 69 mg/kg, p.o.). Topical administration of pinusolide, at 2 mg/ear, was effective in inhibiting croton oil-induced mouse ear oedema. Ears of treated mice fully recovered, in contrast to necrotized ears of untreated animals. It is suggested that pinusolide is a potent and specific PAF-antagonist in vitro and in vivo.

Clove [Syzygium aromaticum] oil inhibited human platelet aggregation induced by arachidonic acid (AA), platelet-activating factor (PAF) or collagen. These results suggest that clove oil has inhibitory effects on platelet aggregation and thromboxane synthesis and may act as an antithrombotic agent.

Mistletoe (Viscum album) Formation of lactose-resistant aggregates of human platelets induced by the mistletoe lectin and differential signaling responses to cell contact formation by the lectin or thrombin.

Ginger Gingerol (0.5-20 æM), isolated from Zingiber officinale, concentration-dependently inhibited the aggregation and release reaction of arachidonic acid- and collagen-induced rabbit platelets, but not those induced by platelet-activating factor, U46619 and thrombin. It is concluded that the antiplatelet action of gingerol is mainly due to the inhibition of thromboxane formation.

Varied plants A review and discussion, with tabulated data from the author’s own studies on the effect of decoctions from Melilotus officinalis (aerial parts), Glycyrrhiza uralensis (underground parts), Salvia officinalis (aerial parts), Dracocephalum moldavica (aerial parts), Piper longum (fruits) and Raphanus sativus (underground parts) on aggregation of rat platelets. The possibility of using preparations from individual species or mixtures from several species is suggested.