Resorcylidene aminoguanidine induces antithrombotic action that is not dependent on its antiglycation activity

Rational Design and Synthesis of 1-(Arylideneamino)-4-aryl-1H-imidazole-2-amine Derivatives as Antiplatelet Agents

Based on previous studies indicating the pharmacophoric role of a hydrazone group and azole rings for antiplatelet aggregation activity, a few series of compounds with both hydrazone and an azole (imidazole) ring in their structures were synthesized, and their platelet aggregation inhibitory effects were evaluated. Two of these 1-(arylideneamino)-4-aryl-1H-imidazole-2-amine derivatives, compounds 4 a [(E)-1-(benzylideneamino)-4-phenyl-1H-imidazol-2-amine] and 4 p [(E)-4-phenyl-1-((thiophen-2-ylmethylene)amino)-1H-imidazol-2-amine], exhibited IC₅₀ values similar to that of acetylsalicylic acid against collagen as a platelet aggregation inducer. Structural comparison of the synthesized compounds revealed that those with a para-substituted phenyl ring on the imidazole were among the most active compounds against platelet aggregation induced by arachidonic acid (AA), and the presence of a thiophene ring in these compounds maximized their antiplatelet activity.

β-Resorcylidene aminoguanidine (RAG) dilates coronary arteries in an endothelium-independent manner

BACKGROUND

β-Resorcylidene aminoguanidine (RAG), a highly reactive derivative of aminoguanidine, possesses antithrombotic activity which involves the activation of the vascular COX-2/PGI2 pathway. This endothelium-dependent effect suggests that RAG may demonstrate vasomotor activity in arterial vessels. The aim of the present study was to investigate a possible vasoactive action of RAG in coronary arteries of rat heart.

METHODS

Isolated rat hearts were perfused in the Langendorff model. To investigate the dose dependency of the effect of RAG on coronary flow, the hearts were perfused with RAG at increasing concentrations. Mechanisms of RAG-mediated vasodilation were subsequently tested using selective inhibitors of the endothelium-dependent and endothelium-independent mechanisms responsible for regulation of vascular tone.

RESULTS

RAG dilated coronary arteries at concentrations above 10(-5)mol/l. Inhibition of the endothelium-dependent mechanism of vasodilation by NG-nitro-L-arginine methyl ester, indomethacin and aminobenzotriazole did not affect RAG-mediated vasodilation. Other compounds also had no impact on the vasodilating effect of RAG: the NO-dependent guanylate cyclase inhibitor - 1H-[1,2,4]oxadiazolo[4,3]quinoxalin-1-one, the cAMP-dependent protein kinase inhibitor - PKAi, and the K(+) channel blockers - glibenclamide, tetraethylammonium, charybdotoxin, and apamin.

CONCLUSIONS

RAG is a strong vasodilator that exerts its effect via endothelium-independent mechanisms.

Resorcylidene aminoguanidine (RAG) improves cardiac mitochondrial bioenergetics impaired by hyperglycaemia in a model of experimental diabetes

Diabetes is associated with a mitochondrial dysfunction. Hyperglycaemia is also clearly recognized as the primary culprit in the pathogenesis of cardiac complications. In response to glycation and oxidative stress, cardiac mitochondria undergo cumulative alterations, often leading to heart deterioration. There is a continuous search for innovative treatment strategies for protecting the heart mitochondria from the destructive impact of diabetes. Aminoguanidine derivatives have been successfully used in animal model studies on the treatment of experimental diabetes, as well as the diabetes-driven dysfunctions of peripheral tissues and cells. Considerable attention has been paid particularly to β-resorcylidene aminoguanidine (RAG), often shown as the efficient anti-glycation and anti-oxidant agent in both animal studies and in vitro experiments. The aim of the present study was to test the hypothesis that RAG improves oxidative phosphorylation and electron transport capacity in mitochondria impaired by hyperglycaemia. Diabetes mellitus was induced in Wistar rats by a single intraperitoneal injection of streptozotocin (70 mg/kg body weight). Heart mitochondria were isolated from healthy rats and rats with streptozotocin-diabetes. Mitochondrial respiratory capacity was measured by high resolution respirometry with the OROBOROS Oxygraph-2k according to experimental protocol including respiratory substrates and inhibitors. The results revealed that RAG protects the heart against diabetes-associated injury by improving the mitochondrial bioenergetics, thus suggesting a possible novel pharmacological strategy for cardioprotection.