Design, synthesis of 2,3-disubstitued 4(3H)-quinazolinone derivatives as anti-inflammatory and analgesic agents: COX-1/2 inhibitory activities and molecular docking studies

Compounds 4 and 6 possessed more potent analgesic and anti-inflammatory activities than celecoxib. Compounds 4 and 6 showed high COX-2 inhibitory efficacies almost similar to celecoxib. [Display omitted] A new series, 2-substituted mercapto-3-[2-(pyridin-2-yl)ethyl]-4(3H)-quinazolinone 1–21, was synthesized and evaluated for in vivo anti-inflammatory and analgesic activities and in vitro COX-1/COX-2 inhibition. Compounds 1, 4, 5, 6, 8, 10, 13, 14, 15, 16, and 17 exhibited potent anti-inflammatory and analgesic properties, with ED50 values of 50.3–112.1mg/kg and 12.3–111.3mg/kg, respectively. These values may be compared with those of diclofenac sodium (ED50=112.2 and 100.4mg/kg) and celecoxib (ED50=84.3 and 71.6mg/kg). Compounds 4 and 6 possessed strong COX-2 inhibitory activity with IC50 (0.33μM and 0.40μM, respectively) and selectivity index (SI>303.0 and >250.0, respectively) values that are similar to those of the reference drug celecoxib (IC50 0.30μM and COX-2 SI>333). Compounds 5, 8, and 13 demonstrated effective COX-2 inhibitory activity with IC50 values of 0.70–0.80μM and COX-2 SI>125–142. Potent COX-2 inhibitors, such as compounds 4, 6, and 13, were docked into the active site pockets of COX-1 and COX-2, with the greatest recognition occurring at the COX-2 binding site and insignificant interactions at the binding site of the COX-1 pocket.