An automated analysis method enabling the screening of covalent thrombin and factor XIIa inhibitors via liquid chromatography-mass spectrometry

An automated sample preparation and separation method for the analysis of various enzyme-inhibitor combinations using liquid chromatography (LC) coupled to mass spectrometry (MS) is presented. As conventional anticoagulants have several drawbacks, the most severe being the elevated risk of internal bleedings, it is necessary to develop new-generation anticoagulants with reduced side effects. Therefore, the screening of potential inhibitors against anticoagulation targets like thrombin and FXIIa is important to design a potent and selective inhibitor. To facilitate the analysis of numerous enzyme-inhibitor covalent complexes, automation of the analysis using an LC system with a user-defined injection sequence is helpful. The developed method ensures comparable reaction conditions like reaction time and temperature for all enzyme-inhibitor complexes. Furthermore, it prevents time-consuming manual sample preparation and potential manual errors. To achieve good reproducibility with relative standard deviation of approximately 3% for three-fold determination, multiple cleaning steps were added to the automated sample preparation. Subsequently, this method was applied to screen a variety of 15 aminopyrazole- and aminotriazole-based inhibitors with a covalent mechanism of action against thrombin and to test two covalent inhibitors for FXIIa. Successful complex formation and acylation of the catalytic center of the enzymes was monitored using deconvoluted mass spectra and the matching mass shifts of the acyl moiety of the analyzed inhibitors. The inhibitors' structure directly influenced reaction yields. Sterically demanding aminotriazoles and acyl moieties both affected the product formation negatively. However, the screening yielded several promising candidates for new covalent thrombin inhibitors, which might find their application as prospective anticoagulants.

Modern metal-catalyzed and organocatalytic methods for synthesis of coumarin derivatives: a review

Coumarin is an important pharmaceutical structural motif, abundantly found in numerous commonly used drugs. Compounds containing this core show a broad spectrum of medicinal properties and biological activities. The increasing importance and wide usages of coumarin derivatives have drawn attention to its synthetic methods, among which metal-catalyzed and organocatalytic methods have proved the most effective. Several metal-catalyzed and/or organocatalytic synthetic strategies for coumarin have been investigated and reported in recent decades. This review focuses on more recent reports on catalysis methods for synthesizing coumarin and coumarin-like structures (including light-mediated methods and nano-catalysts), exploring the mechanistic aspects, simplicity, efficiency, repeatability, and other advantages and disadvantages of these methods.

New oral anticoagulants after acute coronary syndrome

New oral anticoagulants (NOACs) have been developed that may further decrease the mortality and morbidity of ACS by complementing antiplatelet therapy. Optimal use of these agents can be achieved by maximum reduction in thrombotic events at the minimum bleeding risk when combining a long-term oral anticoagulant with anti-platelet therapy in patients with coronary heart disease. Although, based on the pharmacokinetics and -dynamics of NOACs, these agents could improve the current management of ACS patients, multiple trials consistently demonstrate a trend toward increased major and clinically relevant non major bleeding almost diminishing the benefits in reduction of ischemic events. Therefore, some critical issues need to be further evaluated in future trials.