Synthesis of New Tricyclic and Tetracyclic Fused Coumarin Sulfonate Derivatives and Their Inhibitory Effects on LPS-Induced Nitric Oxide and PGE2 Productions in RAW 264.7 Macrophages: Part 2

Article abstract of DOI:10.1002/ardp.201600243

The synthesis of a new series of 21 fused coumarin derivatives is described, and the biological evaluation of their in vitro antiinflammatory effects as inhibitors of lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in RAW 264.7 macrophages. The target compounds 1a–u were first tested for cytotoxicity to determine a non-toxic concentration for antiinflammatory screening, so that the inhibitory effects against NO and PGE₂ production would not be caused by cytotoxicity. Compounds 1f and 1p were the most active PGE₂ inhibitors with IC₅₀ values of 0.89 and 0.95 μM, respectively. Western blot and cell-free COX-2 screening showed that their effects were due to inhibition of both COX-2 protein expression and COX-2 enzyme activity. Their IC₅₀ values against the COX-2 enzyme were 0.67 and 0.85 μM, respectively, which is more potent than etoricoxib. The selectivity indexes of compounds 1f and 1p against COX-2 compared to COX-1 were 41.1 and 42.5, respectively. Compound 1f showed strong inhibitory effects at 5 μM concentration on COX-2 mRNA expression in LPS-induced RAW 264.7 macrophages. Moreover, the tricyclic compounds 1l and 1n as well as the tetracyclic analog 1u were the most potent NO inhibitors, with one-digit micromolar IC₅₀ values. They showed dose-dependent inhibition of inducible nitric oxide synthase (iNOS) protein expression. The tetracyclic derivative 1u was the most potent inhibitor of NO production. It also exhibited a strong inhibitory effect on iNOS mRNA expression in LPS-induced RAW 264.7 macrophages.