Synthesis, evaluation and docking of novel pyrazolo pyrimidines as potent p38α MAP kinase inhibitors with improved anti-inflammatory, ulcerogenic and TNF-α inhibitory properties

Abstract

A series of nine new N-substituted-4-((1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl)amino)benzamides (6a-i) derivatives was synthesized. All the compounds were screened in-vitro for BSA anti-denaturation property, antioxidant assay and p38α MAP kinase inhibition. The in vitro anti-inflammatory assay results revealed that the compounds (6f-i) showed better activity than the compounds 6a-e. Compound 6f bearing the 4-chlorophenyl group showed in vitro anti-inflammatory activity (82.35 ± 4.04) comparable to standard drug diclofenac sodium (84.13 ± 1.63) and better p38α MAP kinase inhibitory activity (IC₅₀ = 0.032 ± 1.63 µM) than the prototypic inhibitor SB203580 (IC₅₀ = 0.041 ± 1.75 µM). The selected active compounds (6f-i) were further studied in animal models for anti-inflammatory activity, ulcerogenic liability, lipid peroxidation and TNF-α inhibition potential. Compound 6f showed promising anti-inflammatory potential with a percentage inhibition of 83.73% when compared to the standard, diclofenac sodium (78.05%). Compound 6f was also found to show reduced ulcerogenic liability and lipid peroxidation in comparison to the standard. This compound also potently inhibited the lipopolysaccharide (LPS)-induced TNF-α production in mice model (ID₅₀ = 8.23 mg/kg) in comparison to SB 203580 (ID₅₀ = 26.38 mg/kg). The molecular docking of compounds 6a-i against p38α MAP kinase receptor was also performed to understand ligand receptor interaction. Amongst all synthesized molecules compound 6f displayed highest docking score of -9.824. It showed hydrogen bonding interactions with Asn115 and pi-cation interaction with Lys53.

Keywords: Anti-inflammatory; Docking; Pyrazolo pyrimidine; TNF-α inhibition; p38α MAP kinase.