Protective effect of piceatannol and bioactive stilbene derivatives against hypoxia-induced toxicity in H9c2 cardiomyocytes and structural elucidation as 5-LOX inhibitors.

Stilbenes with well-known antioxidant and antiradical properties are beneficial in different pathologies including cardiovascular diseases. The present research was performed to investigate the potential protective effect of resveratrol (1) and piceatannol (2), against hypoxia-induced oxidative stress in the H9c2 cardiomyoblast cell line, and the underlying mechanisms. Compounds 1 and 2 significantly inhibited the release of peroxynitrite and thiobarbituric acid levels at na no- or submicromolar concentrations, and this effect was more evident in piceatannol-treated cells, that significantly increased MnSOD protein level in a concentration dependent manner. Furthermore, since piceatannol, which is far less abundant in natural sources, displayed a higher bioactivity than the parent compound, we hereby report on a very fast synthesis and detailed structure-based design of a focused stilbene library. Finally, taking into account that hypoxia-induced ROS accumulation also increases expression and activity of 5-lipoxygenase (5-LOX) with production of leukotrienes, we have disclosed structural key factors crucial for 5-LOX activity. Among the synthesized analogues ( 3-7), compound 7 was the most effective in improving cardiomyocytes viability and in 5-LOX inhibition. In conclusion, modeling and experimental studies provided the basis for further optimization of stilbene analogues as multi-target inhibitors of the inflammatory and oxidative pathway.

Exploring the role of chloro and methyl substitutions in 2-phenylthiomethyl-benzoindole derivatives for 5-LOX enzyme inhibition.

Following the results we previously reported on a series of ethyl 2-phenylthiomethyl 5-hydroxyindole-3-carboxylate derivatives as 5-lipoxygenase (5-LOX) inhibitors, in order to obtain a more selective compound with respect to the previous generation of derivatives, we decided to modify the structure of the core ligand. The first level of structural modification involved the annelation of benzene to the indole, yielding corresponding benzo[g]indole derivatives, systematic optimization of methyl or chlorine groups in meta-, ortho- and ortho/para-position of 2-phenylthiomethyl moiety were applied. The reported results show that extension of the aromatic core led to a great enhancement of activity, especially in cell-free assay, and the accurate structure-based design provided compounds 6f, 6g and 6l that block 5-LOX activity in cell-free assays with IC50 ranging from 0.17 to 0.22 µM, and suppress 5-LOX product synthesis in polymorphonuclear leukocytes with IC50 ranging from 0.19 to 0.37 µM. Moreover we have identified 6f and 6l as dual 5-lipoxygenase (5-LO) and microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors and compound 6l significantly reduces inflammatory reactions in the carrageenan-induced mouse paw oedema. The reported in vivo analysis, together with the accessible synthetic procedure, stimulate for the generation of further potent antinflammatory benzoindoles-based agents.