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

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, ¹³CNMR, 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.