Screening of curcumin-derived isoxazole, pyrazoles, and pyrimidines for their anti-inflammatory, antinociceptive, and cyclooxygenase-2 inhibition.

Curcumin has shown pharmacological properties against different phenotypes of various disease models. Different synthetic routes have been employed to develop its numerous derivatives for diverse and improved therapeutic roles. In this study, we have synthesized curcumin derivatives containing isoxazole, pyrazoles, and pyrimidines and then the synthesized molecules were evaluated for their anti-inflammatory and antinociceptive activities in experimental animal models. Acute toxicity of synthesized molecules was evaluated in albino mice by oral administration. Any behavioral and neurological changes were observed at dose of 10 mg/kg body weight. Additionally, cyclooxygenase-2 (COX-2) enzyme inhibition studies were performed through in vitro assays. In vivo anti-inflammatory studies showed that curcumin with pyrimidines was the most potent anti-inflammatory agent which inhibited induced edema from 74.7% to 75.9%. Compounds 7, 9, and 12 exhibited relatively higher prevention of writhing episodes than any other compound with antinociceptive activity of 73.2%, 74.9%, and 71.8%, respectively. This was better than diclofenac sodium (reference drug, 67.1% inhibition). Similarly, COX-2 in vitro inhibition assays results revealed that compound 12 (75.3% inhibition) was the most potent compound. Molecular docking studies of 10, 11, and 12 compounds in human COX-2 binding site revealed the similar binding modes as that of other COX-2-selective inhibitors.