The development of new anticoagulants is an important goal for the improvement of thromboses treatments. The design, synthesis and experimental testing of new safe and effective small molecule direct thrombin inhibitors for intravenous administration. Computer-aided molecular design of new thrombin inhibitors was performed using our original docking program SOL, which is based on the genetic algorithm of global energy minimization in the framework of a Merck Molecular Force Field. This program takes into account the effects of solvent. The designed molecules with the best scoring functions (calculated binding energies) were synthesized and their thrombin inhibitory activity evaluated experimentally in vitro using a chromogenic substrate in a buffer system and using a thrombin generation test in isolated plasma and in vivo using the newly developed model of hemodilution-induced hypercoagulation in rats. The acute toxicities of the most promising new thrombin inhibitors were evaluated in mice, and their stabilities in aqueous solutions were measured. New compounds that are both effective direct thrombin inhibitors (the best K_I was 1111.1 mg/kg. A plasma-substituting solution supplemented with one of the new inhibitors prevented hypercoagulation in the rat model of hemodilution-induced hypercoagulation. Activities of the best new inhibitors in physiological saline (1 µM solutions) were stable after sterilization by autoclaving, and the inhibitors remained stable at long-term storage over more than 1.5 years at room temperature and at 4°C. The high efficacy, stability and low acute toxicity reveal that the inhibitors that were developed may be promising for potential medical applications.

The search of selective agonists and antagonists of membrane progesterone receptors (mPRs) is a starting point for the study of progesterone signal transduction mechanisms mediated by mPRs, distinct from nuclear receptors. According to preliminary data, the ligand affinity for mPRs differs significantly from that for classical nuclear progesterone receptors (nPRs), which might indicate structural differences in the ligand-binding pocket of these proteins. In the present work, we analyzed the affinity of several progesterone derivatives for mPRs of human pancreatic adenocarcinoma BxPC3 cell line that is characterized by a high level of mPR mRNA expression and by the absence of expression of nPR mRNA. The values were compared with the affinity of these compounds for nPRs. All tested compounds showed almost no affinity for nPRs, whereas their selectivity towards mPRs was different. Derivatives with an additional 19-hydroxyl group and removed 3-keto group had the highest selectivity for mPRs. These results suggest these compounds as the most selective progesterone analogs for studying the mechanisms of progestin action via mPRs.