Synthesis of Asymmetric Thiazolyl Pyrazolines as a Potential Antioxidant and Anti-Inflammatory Agents

Abstract

A new series of 1-Thiazolyl-2-Pyrazolines 5a-g was accomplished by reacting pyrazolealdehyde with an appropriate aromatic ketone in the presence of PEG-300 as a solvent to yield chalcone. The chalcones reacted with thiosemicarbazide to yield asymmetric 1-thiocarbamoyl pyrazoles. The above formed 1-thiocarbamoyl pyrazoles reacted with appropriate α- haloketones to yield 1-Thiazolyl-2-Pyrazolines. The structural interpretations of newly formed compounds were done by 1H NMR, 13 E. Palaska, M. Aytemir, I. Tayfun Uzbay, D. Erol, et al. “Synthesis and Antidepressant Activities of Some 3,5-Diphenyl-2-Pyrazolines,” European Journal of Medicinal Chemistry 36, no. 6 (2001): 539–43.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]CNMR, IR and mass spectroscopic methods. The newly prepared asymmetric 1-Thiazolyl-2-pyrazoline derivatives were evaluated to their in vitro antioxidant (H2O2, DPPH, SOR and NO radical inhibiting activity) as well as anti-inflammatory activity. The 1-Thiazolyl-2-pyrazoline derivatives 5a-g exhibited moderate to good H2O2 scavenging activity as match up to ascorbic acid. All the 1-Thiazolyl-2-pyrazoline derivatives exhibited excellent SOR scavenging activity except 5 b. All the tested compounds have shown good to excellent, NO radical inhibiting activity. DPPH radical scavenging activity results have shown low antioxidant activity. Also, all the 1-Thiazolyl-2-pyrazoline derivatives were tested for their in vitro anti-inflammatory activity. The compounds 5a, 5 b, 5c, 5f and 5 g were exhibited good anti-inflammatory activity and 5d showed moderate activity while 5e less active as match up to diclofenac sodium as a standard reference.