Paraoxonase-1 activity affects the clopidogrel response in CYP2C19 loss-of-function carriers

Multiple genetic mutations increase the risk of thrombosis associated with clopidogrel after percutaneous coronary intervention

Background: The effect of multiple mutations in CYP2C19, PON1 and ABCB1 genes on the effectiveness and safety of dual antiplatelet therapy after percutaneous coronary intervention remains unclear. Methods: In total, 263 Chinese Han patients were enrolled in this study. Platelet aggregation rates and thrombosis risk were used to compare clopidogrel responses and outcomes in patients with different numbers of genetic mutations. Results: Our study demonstrated that 74% of the patients carried more than two genetic mutations. High platelet aggregation rates were associated with genetic mutations in patients receiving clopidogrel and aspirin after percutaneous coronary intervention. Genetic mutations were closely related to the recurrence of thrombotic events, but not bleeding. The number of genes that become dysfunctional in patients is directly correlated with the risk of recurrent thrombosis. Conclusion: Compared with CYP2C19 alone or the platelet aggregation rate, it is more helpful to predict clinical outcomes by considering the polymorphisms of all three genes.

Clopidogrel as a donor probe and thioenol derivatives as flexible promoieties for enabling H2S biomedicine

Hydrogen sulfide has emerged as a critical endogenous signaling transmitter and a potentially versatile therapeutic agent. The key challenges in this field include the lack of approved hydrogen sulfide-releasing probes for in human exploration and the lack of controllable hydrogen sulfide promoieties that can be flexibly installed for therapeutics development. Here we report the identification of the widely used antithrombotic drug clopidogrel as a clinical hydrogen sulfide donor. Clopidogrel is metabolized in patients to form a circulating metabolite that contains a thioenol substructure, which is found to undergo spontaneous degradation to release hydrogen sulfide. Model studies demonstrate that thioenol derivatives are a class of controllable promoieties that can be conveniently installed on a minimal structure of ketone with an α-hydrogen. These results can provide chemical tools for advancing hydrogen sulfide biomedical research as well as developing hydrogen sulfide-releasing drugs.

Hydrogen sulphide (H₂S) is a gaseous signalling molecule, which has shown therapeutic value. Here, the authors show that a thioenol metabolite of the antithrombotic drug clopidogrel is an efficient H₂S donor and masked thioenols can be linked to existing compounds to develop H₂S-releasing agents.

Paraoxonases: metabolic role and pharmacological projection

Atherosclerosis is one of the leading causes of death in Western countries, with high-density lipoproteins (HDL) playing an important protective role due to their ability to inhibit oxidation of low-density lipoproteins (LDL), thus relieving vascular subendothelial damage. One of the proteins constituting HDL particles is paraoxonase-1 (PON1), an enzyme able to hydrolyze aryl esters, lactones, and organophosphates. Other closely related paraoxonases are designated as PON2, which is a protein localized inside many different kinds of cells, and PON3, not only present in HDL but also in mitochondria and endoplasmic reticulum, as well. Given that the amount and the activity of PON1 in human serum are significantly lower in people suffering from cardiovascular diseases, enhancing both parameters might contribute to their treatment and prevention. One of the physiologically interesting substrates for the abovementioned hydrolytic cleavage is homocysteine thiolactone (HTL), an atherothrombotic active form of homocysteine. Although it was therefore postulated that PON1 would participate in preventing the HTL-mediated lipid peroxidation, some attention is recently paid to other enzymes, like biphenyl hydrolase-like protein, that seem to more selectively involved in lowering this risk factor. The aim of this paper is to elucidate the role of paraoxonases, especially PON1, by reviewing the latest studies in order to understand both its physiological role and modulation by drugs, nutrients, and plant extracts.