Inhibition of Plasma Coagulation and Platelet Aggregation with Structural Analogs of Taurine Chloramine

Antiplatelet Action of Chloramine Derivatives of Adenosine Phosphates and Their Chemical Activity in Relation to Sulfur-Containing Compounds

We studied the properties of N6-chloroadenosine phosphates (ATP, ADP, and AMP chloramines) as compounds with potentially increased antiplatelet efficacy determined by their binding to the plasma membrane of platelets. Chloramine derivatives of ATP, ADP, and AMP do not differ in their optical absorption characteristics: their absorption spectra are in the range of 220-340 nm with a maximum at 264 nm. Chloramines of adenosine phosphates are characterized by high reactivity with respect to thiol compounds. In particular, the rate constants of the reaction of N6-chloroadenosine-5'-diphosphate with N-acetylcysteine, reduced glutathione, dithiothreitol, and cysteine reach 59,000, 250,000, 340,000, and 1,250,000 M^-1×sec^-1, respectively, and only 1.10±0.02 M^-1×sec^-1 with methionine. It has been found that N6-chloradenosine-5'-triphosphate is a strong inhibitor of platelet functions: it effectively suppresses ADP-induced cell aggregation (IC₅₀ in the whole blood is 5 μM) and inhibits aggregation of preactivated platelets and induces dissociation of their aggregates.

Taurine and Its Derivatives: Analysis of the Inhibitory Effect on Platelet Function and Their Antithrombotic Potential

Taurine is a semi-essential, the most abundant free amino acid in the human body, with a six times higher concentration in platelets than any other amino acid. It is highly beneficial for the organism, has many therapeutic actions, and is currently approved for heart failure treatment in Japan. Taurine has been repeatedly reported to elicit an inhibitory action on platelet activation and aggregation, sustained by in vivo, ex vivo, and in vitro animal and human studies. Taurine showed effectiveness in several pathologies involving thrombotic diathesis, such as diabetes, traumatic brain injury, acute ischemic stroke, and others. As human prospective studies on thrombosis outcome are very difficult to carry out, there is an obvious need to validate existing findings, and bring new compelling data about the mechanisms underlying taurine and derivatives antiplatelet action and their antithrombotic potential. Chloramine derivatives of taurine proved a higher stability and pronounced selectivity for platelet receptors, raising the assumption that they could represent future potential antithrombotic agents. Considering that taurine and its analogues display permissible side effects, along with the need of finding new, alternative antithrombotic drugs with minimal side effects and long-term action, the potential clinical relevance of this fascinating nutrient and its derivatives requires further consideration.