Stilbene-pyridazinone hybrids: design, synthesis and in vitro antiplatelet activity screening

A series of stilbene analogues, in which a phenyl ring was replaced by the pyridazin-3(2H)-one nucleus, was designed and synthesized to be explored as platelet aggregation inhibitors. The proposed stilbene-pyridazinone hybrids were successfully obtained from simple starting materials and by Wittig's reaction. Most of the target compounds displayed improved in vitro activity in comparison with the standard drug, resveratrol, highlighting as the most potent the analogues 10d and 10e, with inhibition percentages of 94.15 % at 100 µM and 100 % at 50 µM, respectively. The pharmacokinetic and toxicity (ADME/T) properties of the novel hybrids were also estimated with the SwissADME and ProTox-II web servers.

The antithrombotic activity of natural and synthetic coumarins

Thrombosis, which seriously endangers human health and life, is the leading cause of morbidity and mortality globally. Antithrombotic drugs can interfere with the occurrence and development of thrombotic diseases and play an important role in the treatment of thrombotic diseases. However, unsatisfactory efficacy and serious adverse effects of existing antithrombotic drugs increase the research for new, efficient and safer drugs. Natural and synthetic coumarins have been shown to possess antithrombotic activity, namely, anticoagulation and antiplatelet aggregation. Especially, coumarin-based warfarin, phenprocoumon and cloricromen have long been used in clinical treatment of thrombosis. Coumarin with low toxicity is the privileged structure for developing novel antithrombotic drugs with multiple mechanisms of action. The present review aims to compile current research on the development of coumarins against thrombosis, emphasizing the relationship between their chemical structures and therapeutic effectiveness. It is intended to provide promising ideas for the discovery of novel coumarin derivatives with high antithrombotic activity.

Novel coumarin-pyridazine hybrids as selective MAO-B inhibitors for the Parkinson's disease therapy

The 3-pyridazinylcoumarin scaffold was previously reported as an efficient core for the discovery of reversible and selective inhibitors of MAO-B, a validated drug target for PD therapy which also plays an important role in the AD progress. Looking for its structural optimization, novel compounds of hybrid structure coumarin-pyridazine, differing in polarizability and lipophilicity properties, were synthesized and tested against the two MAO isoforms, MAO-A and MAO-B (compounds 17a-f and 18a-f). All the designed compounds selectively inhibited the MAO-B isoenzyme, exhibiting many of them IC₅₀ values ranging from sub-micromolar to nanomolar grade and lacking neuronal toxicity. The 7-bromo-3-(6-bromopyridazin-3-yl)coumarin (18c), the most potent compound of these series (IC₅₀ = 60 nM), was subjected to further in vivo studies in a reserpine-induced mouse PD model. The obtained results suggest a promising potential for 18c as antiparkinsonian agent. Molecular modeling studies also provided valuable information about the enzyme-drug interactions and the potential pharmacokinetic profile of the novel compounds.