Analgesic and anti-inflammatory activity of quinoxaline derivatives: Design synthesis and characterization

Medicinal chemistry is a basic science that involves identification, synthesis and development of new drugs for therapeutic use. Biological importance of heterocycles makes them more crucial in pharmaceutical industries. In this work heterocyclics like quinoxaline and its derivatives were prepared. Different quinoxalines such as biphenyl quinoxaline, quinoxaline dione and quinoxaline-2-one were synthesized by different synthetic routes. All the quinoxaline derivatives were obtained with better yields and high purity. Substituted quinoxaline derivatives were subjected to biological evaluation which include analgesic and invitro anti inflammatory activity. The progress of the reaction was monitored by physical constants such as TLC, melting point and Rf values were determined. The structural elucidation is done by IR, Mass and 1H NMR spectral data. Among all quinoxalines 2, 5, 9, 14f and 17c revealed significant analgesic activity with percentage protection of 56.90, 68.68, 67.70, 66.33 and 68.79 respectively. The standard drug aspirin exhibited 70.50 % with 30 mg/kg body weight. Among the synthesized quinoxalines, 3, 11, 14d and 17e were found to bring about a decrease in oedema such as 53. 91, 48.72, 46.77 and 46.85 percentage reduction in oedema comparable to that of standard Indomethacin 10 mg/kg bodyweight 49.00 % reduction in oedema. All the quinoxaline derivatives were screened for different activities like analgesic activity by acetic acid induced writhing method in mice and anti inflammatory activity by using the 'carrageenan induced paw oedema method' in rats. The search of more suitable anti inflammatory agent and acute pain is well accounted in terms of nociception.