Elsevier

Thrombosis Research

Volume 126, Issue 1, July 2010, Pages e17-e22
Thrombosis Research

Regular Article
Antiplatelet and antithrombotic activities of salvianolic acid A

https://doi.org/10.1016/j.thromres.2010.04.006Get rights and content

Abstract

Introduction

Salvianolic acid A (SAA), the water-soluble phenolic acids in Salvia miltiorrhiza, has shown the most potent bioactivities, including protection against cerebral lesion, defense from oxidative damage and improvement of remembrance. In the present study, we studied the antiplatelet and antithrombotic effects of a newly synthesized SAA with different methods both in vitro and in vivo.

Materials and Methods

We tested the effect of antithrombotic activity of SAA in arterio-venous shunt model. The effects of SAA on adenosine diphosphate (ADP)–, Thrombin–, Arachidonic acid– induced rat platelets aggregation were tested both in vivo and in vitro. The activity of SAA on washed human platelet aggregation was determined by ADP stimulation. We also evaluated its property of modulation of hemorheology, assessed its bleeding side effect by measuring coagulation parameters after intravenous administration for 5 days and investigated the potential mechanisms underlying such activities.

Results and Conclusions

In vivo, SAA significantly reduced thrombus weight in the model of arterio-venous shunt. Meanwhile, SAA increased plasma cAMP level determined by radioimmunoassay in the same model. Intravenously administrated SAA (2.5–10 mg/kg) inhibited platelet aggregation induced by ADP in a dose-dependent manner. Notably, SAA did not affect coagulation parameters in rats after intravenous administration SAA for successive 5 days. In vitro, pretreatment with SAA on washed rat and human platelets significantly inhibited various agonists stimulated platelet aggregation and caused an increase in cAMP level in platelets activated by ADP. These findings support our hypothesis that SAA possesses antithrombotic activities. The antithrombotic effect might be related to its antiplatelet action and ability to modulate hemorheology without affecting coagulation system. The mechanisms underlying such activities may involve the induction of cAMP.

Introduction

It is widely accepted that thrombus formation affects the progression of various cardiovascular or cerebrovascular disorders, including unstable angina, myocardial infarction, transient ischemic attack, and atherosclerosis [1]. Platelets play an important role in thrombus formation at the site of damaged blood vessels [2], [3], especially arterial and microvascular thrombi, which are major causes of cardiovascular and cerebrovascular diseases [1], [4]. Collaborative meta-analysis of randomized trials has shown that antiplatelet therapy prevents serious vascular events, arterial occlusion, and venous thromboembolism among a wide range of patients at high risk for occlusive vascular event [5]. Therefore, agents with antiplatelet and antithrombotic effects could have wide therapeutic potential for circulatory diseases [6], [7].

Danshen is the dried root of Salvia miltiorrhizae (Labiatae) and is one of the most versatile Chinese herbal drugs. It has been used clinically to treat and prevent cardiovascular disease, hyperlipidemia, and cerebrovascular disease throughout the world [8], [9], [10]. Salvianolic acid A (SAA, the chemical structure is presented in Fig. 1.) is one of major water-soluble phenolic acids extracted from Danshen. Among seven water-soluble compounds, SAA has shown the most potent protective action against peroxidative damage to biomembranes [11]. Pharmacological tests have revealed that SAA possesses a variety of pharmacological activities. It was found to protect against focal cerebral ischemia and inhibit platelet aggregation by collagen-induced. The effects were better than other water-soluble compounds [12], [13].

However, the natural extracted SAA is low in content, which limits its clinical application. Therefore, synthesis of SAA through chemical conversion of raw material salvianolic acid B (SAB) has been developed by Target Drug Research Co. Ltd. This method could be scaled up for large-scale industrial production. The objective of the present study was to assess the effect of newly synthesized SAA on platelet aggregation, thrombus formation, and blood circulation and to provide pharmacological evidence for clinical applications. In addition, potential underlying mechanisms were also investigated.

Section snippets

Reagents and animals

SAA was provided by Target Drug Research Co. Ltd (Shandong, China). L-lysine aspirin was produced by Anhui Fengyuan Pharmaceutical Co. Ltd (Anhui, China). Heparin sodium injection was purchased from Jiangsu Wanbang Biochemical Medicine Co. Ltd. (Jiangsu, China). Adrenaline hydrochloride was purchased from Tianjin Jinyao amino acids Co. Ltd. (Tianjin, China). Adenosine diphosphate (ADP) was purchased from Shanghai Lanji Biotechnology Co. Ltd. (Shanghai, China). The thromboxane B2 (TXB2) and

Effect on washed rat and human platelet aggregation in vitro

SAA exerted inhibitory effects on ADP, thrombin, and AA-induced platelet aggregation. As shown in Fig. 2, SAA effectively inhibited ADP-induced (10 µM) rat platelet aggregation with IC50 of 390 µg/ml and inhibited thrombin-induced (0.7 U/ml) platelet aggregation with IC50 of 912 µg/ml. In contrast, SAA exerted only mild inhibitory effects (39%) on AA-induced (0.5 mM) platelet aggregation, even at the high concentration of 1000 µg/ml. In addition, ASA (72 µg/ml) and IBMX (76 µg/ml) also considerably

Discussion

In the present study, we examined the antiplatelet and antithrombotic effects of newly synthesized SAA and the pharmacological mechanisms by which it improves blood microcirculation by evaluating its hemorheologic, coagulation, and antiplatelet aggregative activity both in vivo and in vitro. The findings from our study enable the better understanding of SAA, which could ultimately lead to the development of novel pharmaceutical strategies for the treatment of thrombosis diseases.

Our results

Conflict of interest statement

The authors state that they have no conflict of interest.

Acknowledgements

This study was supported by the Programs for Science and Technology Development and Plan of Yantai (No. 2009167).

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