Synthesis and free radical scavenging activity of coumarin derivatives containing a 2-methylbenzothiazoline motif.

Coumarin and benzothiazole scaffolds can be found in a number of natural or synthetic antioxidants. In an effort to develop a novel radical scavenger and potential antioxidant, a series of coumarin derivatives containing 2-methylbenzothiazoline motif and related compounds was synthesized and evaluated for their DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS(•+) (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radicals scavenging activities. Among them, 7-hydroxy-3-(2-methyl-2,3-dihydrobenzo[d]thiazol-2-yl)-2H-chromen-2-one (3e) has shown a significant free radical scavenging activity. From the structure-activity point of view, it was found that phenolic coumarin ring and benzothiazoline moiety in target compounds may contribute to the scavenging activity against free radicals.