Synthesis of 4-methylcoumarin derivatives containing 4,5-dihydropyrazole moiety to scavenge radicals and to protect DNA

A series of 4-methylcoumarin derivatives containing 4,5-dihydropyrazole moiety were synthesized and their antioxidant activities were evaluated in AAPH (2,2′-azobis(2-amidinopropane hydrochloride))-induced oxidation of DNA, and in trapping DPPH (2,2′-diphenyl-1-picrylhydrazyl) and ABTS+• (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical), respectively. Among coumarin derivatives, 3a–d and 4a–c exhibited the termination of radical propagation-chains in AAPH-induced oxidation of DNA. The ortho dihydroxyphenyl substitution at 5 position and 1-unsubstitution of the 4,5-dihydroxylpyrazole was found enhancing the antioxidant activities of these coumarin derivatives.

Graphical abstractA series of 4-methylcoumarin derivatives containing 4,5-dihydropyrazole moiety was synthesized and their antioxidant capacities were evaluated. Compound 3b and 4a were determined as potent antioxidant to scavenge radicals and to protect DNA.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of new 4-methylcoumarin derivatives containing 4,5-dihydropyrazole moiety were synthesized. ► These compounds possessed antioxidant activity to scavenge radicals and to protect DNA. ► The N–H group in 4,5-dihydropyrazole ring could increase antioxidant effectiveness. ► Two hydroxyl groups ortho to each other in benzene ring possess higher antioxidant capacity.