Synthesis of some novel pyrazoline and pyrazole derivatives as potential in vitro anti-xanthine oxidase and antioxidant activities

Abstract

2-Pyrazolines and 2-pyrazole, electron-rich nitrogen containing heterocyclic systems, play an important role in several biological and pharmacological activities. in this paper, we report the synthesis of novel 3,5-disubtituted-2-pyrazoline and pyrazole derivatives (2a-b, 3a-b) starting from azachalcones (1a, 1b). the structure of the synthesised compounds were judged by H-1 NMR, C-13 NMR and IR. the synthesised 3,5-disubtituted- 2-pyrazoline and pyrazole derivatives were evaluated in vitro for their xanthine oxidase (XO) inhibitory activities, with most of the investigated compounds being shown to be potent inhibitors of bovine milk XO. Antioxidant activities of the synthesised compounds (1a, 1b, 2a-b, 3a-b) were determined with CUPric Reducing Antioxidant Capacity (CUPRAC), ABTS (2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)/Persulphate and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. Pyrazoline and pyrazol derivatives also revealed notable antioxidant activities in DPPH scavenging (SC50: 9.91-15.16 mu g/mL) and cupric reducing/antioxidant capacity (5.68-10.56 mM TEAC) tests. Also, compounds 3-(3-methylthiophen-2-yl)-5-(2-pyridinyl)-1H-pyrctzoline (2a) and 3-(4-methylthiophen-2-yl)-5-(2-pyridinyl)-1H-pyrazoline (2b) were found to be more potent radical scavenging activity than butylated hydroxy toluene (BHT) to ABTS(center dot+ )radical cation decolorisation assay.