Synthesis, characterization and anti-inflammatory activity evaluation of 1,2,4-triazole and its derivatives as a potential scaffold for the synthesis of drugs against prostaglandin-endoperoxide synthase.

Substituted 1,2,4-triazole nucleus is common in several drugs used in a variety of clinical conditions including infections, hypoglycemia, hypertension and cancer. In this study, we synthesized 1,2,4-triazole and its 16 hydrazone derivatives (B1-B16), characterized them by IR, NMR and Mass spectroscopy, and evaluated their radical scavenging and anti-inflammatory activities in vitro and in vivo. Out of 16 derivatives, five (B1, B5, B6, B9, and B13) demonstrated a significant radical scavenging and anti-inflammatory activity in vitro. B6, which possessed two electron-donating hydroxyl groups, was most active among all. Molecular docking and MD simulation of the complex of B6 with prostaglandin-endoperoxide synthase (PTGS) or cyclooxygenase (COX) showed that B6 occupied celecoxib binding site in COX with high affinity (the binding free energy of the complex with COX-1 was -10.5, and -11.2 kcal/mol with COX-2). Maximum anti-inflammatory activity was also shown by the B6 derivative in vivo, in the rat model of carrageenan-induced inflammation. B6, along with four other derivatives (B1, B5, B9 and B13) exhibited 80-90% free radical scavenging activity. The IC50 values of these compounds were ≥40 µM. Griess nitrite and dichloro-dihydro-fluorescein-diacetate assays suggested a significant inhibition of nitric oxide and reactive oxygen species, especially by B6 and B9. Taken together, out of 16 derivatives, B6 is reported to have highest anti-inflammatory and antioxidant activity at a low dose level, which may be attributed to its two electron-donating hydroxyls. B6 is proposed to be an important scaffold for the synthesis of new drugs against PTGS for use in a myriad of inflammatory and infectious diseases.Communicated by Ramaswamy H. Sarma.