Hydrogen Sulfide–Releasing Aspirin Derivative ACS14 Exerts Strong Antithrombotic Effects In Vitro and In Vivo

Objective— Hydrogen sulfide (H 2 S)–releasing NSAIDs exert potent anti-inflammatory effects beyond classical cyclooxygenase inhibition. Here, we compared the platelet inhibitory effects of the H 2 S-releasing aspirin derivative ACS14 with its mother compound aspirin to analyze additional effects on platelets. Methods and Results— In platelets of mice fed with ACS14 for 6 days (50 mg/kg per day), not only arachidonic acid–induced platelet aggregation but also ADP-dependent aggregation was decreased, an effect that was not observed with an equimolar dose of aspirin (23 mg/kg per day). ACS14 led to a significantly longer arterial occlusion time after light-dye–induced endothelial injury as well as decreased thrombus formation after ferric chloride-induced injury in the carotid artery. Bleeding time was not prolonged compared with animals treated with equimolar doses of aspirin. In vitro, in human whole blood, ACS14 (25–500 µmol/L) inhibited arachidonic acid–induced platelet aggregation, but compared with aspirin additionally reduced thrombin receptor–activating peptide–, ADP-, and collagen-dependent aggregation. In washed human platelets, ACS14 (500 µmol/L) attenuated αIIbβ3 integrin activation and fibrinogen binding and increased intracellular cAMP levels and cAMP-dependent vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Conclusion— The H 2 S-releasing aspirin derivative ACS14 exerts strong antiaggregatory effects by impairing the activation of the fibrinogen receptor by mechanisms involving increased intracellular cyclic nucleotides. These additional antithrombotic properties result in a more efficient inhibition of thrombus formation in vivo as achieved with aspirin alone.