Design and development of an isatin-1,2,3-triazole hybrid analogue as a potent anti-inflammatory agent with enhanced efficacy and gene expression modulation.

Isatin (1H-indole-2,3-dione) and its derivatives have been found to exhibit various biological activities, including anticancer and antidiabetic properties. In this study, a series of nine isatin-1,2,3-triazole conjugates were synthesized and evaluated for their anti-inflammatory potential via in vitro experiments. Their synthesis involved the propargylation of isatin 1 with propargyl bromide to obtain N-propargyl isatin 2, which was subjected to click reactions with different aromatic azides to yield isatin-N-1,2,3-triazoles (3a-i). The structures of all the compounds were confirmed via NMR and HR-MS. The final isatin analogues were tested for their ability to attenuate the production of proinflammatory cytokines in the lipopolysaccharide (LPS)-induced human leukemia monocytic THP-1 cells. Importantly, none of the compounds had any negative effect on THP-1 cell viability at the tested concentrations of 4 mM and 8 mM. LPS induced the production of the cytokines: Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) by 351.4, 7.9 and 14.3 fold, respectively, in THP-1 cells. However, treatment with compound 3e markedly attenuated the levels of TNF-α (by 6.6 fold and 1.5 fold), IL-6 (by 1.03 fold and 1.41 fold) and MCP-1 (by 3.3 fold and 1.7 fold) by several fold at concentrations of 4 mM and 8 mM, respectively. Furthermore, in the gene expression modulation studies, 3e was found to downregulate the genes responsible for the production of TNF-α (24 and 25 fold), IL-6 (148 and 502 fold) and MCP-1 (50 and 25 fold) at the two tested concentrations compared with their expression in the LPS-induced THP-1 cells (135 fold, 6612 fold, and 68.8 fold, respectively). Thus, 3e markedly attenuated the secretion of TNF-α, IL-6 and MCP-1 from LPS-treated THP-1 cells, and also the expression of the concerned genes. At the lowest dose tested, i.e., 4 mM, 3e had the greatest effect on both gene expression and marker secretion.