Dendritic antioxidants with pyrazole as the core: Ability to scavenge radicals and to protect DNA

Abstract

Chalcones with or without a para-hydroxyl group were condensed with phenylhydrazine-related compounds to form 1,3,5-triphenyl-1H-pyrazole (TPP), 4-(1,5-diphenyl-1H-pyrazol-3-yl)phenol (APP), 4-(1,3-diphenyl-1H-pyrazol-5-yl)phenol (BPP), and 4-(3,5-diphenyl-1H-pyrazol-1-yl)phenol (CPP), in which the phenyl group formed a dendritic structure with pyrazole as the core. Thus, the aim of this work was to explore the antioxidant capacities of TPP, APP, BPP, and CPP in trapping 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+•) and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) and in inhibiting Cu2+/glutathione (GSH)-, •OH-, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation of DNA. TPP can react with ABTS+• and DPPH, indicating that the N atom in pyrazole possesses radical-scavenging ability. Moreover, APP, BPP, and CPP can trap 1.71, 1.81, and 1.58 radicals, respectively, in protecting DNA against AAPH-induced oxidation. Thus, the combination of pyrazole with a phenyl group exerted antioxidant ability although only one phenolic hydroxyl group was involved. However, these compounds showed weak protective effect against Cu2+/GSH-induced oxidation of DNA and even a pro-oxidant effect on •OH-induced oxidation of DNA.