Selected thiourea derivatives of naproxen as potential anti-inflammatory agents: in vivo, in vitro, and in silico approach

Abstract

The aim of the conducted study was to develop new potential dual COX-2 and 5-LOX inhibitors based on naproxen scaffold. We performed the evaluation of in vivo and in vitro anti-inflammatory activity of newly synthesized thiourea derivatives of naproxen containing m-anisidine and N-methyl tryptophan methyl ester in a side chain. An in vivo study was carried out using a carrageenan-induced paw edema model of acute inflammation. COX-2 and 5-LOX inhibitory potential of synthesized compounds was evaluated using fluorometric inhibitor screening kits. In silico study was performed in OEDocking 3.2.0.2 software with the FRED tool. Two investigated derivatives exhibited comparable anti-inflammatory activity to naproxen (56.32%) four hours after injection of carrageenan, with the percentage of inhibition being 54.01% (m-anisidine derivative) and 54.12% (N-methyl tryptophan methyl ester derivative). In vitro studies of COX-2 inhibition demonstrated that none of the tested compounds achieved 50% inhibition at concentrations below 100 μM, whereas the m-anisidine derivative accomplished comparable inhibition of 5-LOX (IC50 = 0.30 μM) to commercial 5-LOX inhibitor zileuton (IC50 = 0.36 μM). Inability of the tested compounds to form three hydrogen bonds with ARG120 and TYR355 could be a reason why these compounds showed weak COX-2 inhibition. The m-anisidine derivative formed a more stable complex with the 5-LOX enzyme (−8.39 kcal/mol), compared to N-methyl tryptophan methyl ester derivative (−7.98 kcal/mol), with the absence of the iron ion chelation in the active site in both cases. The significant in vivo anti-inflammatory activity of the m-anisidine derivative, together with the potent inhibition of 5-LOX, highlighted this compound as a promising anti-inflammatory agent.