Radical scavenging activities and composition identification of phenolic compounds from crowndaisy seeds by offline HPLC combined with LC–ESI–MS/MS

How to screen and evaluate the radical scavenging activity of each compound in the mixture remains a challenging project. In the present study, a sensitive and selective method of offline HPLC coupled with chemical methodology was developed for the evaluation of the radical scavenging activity of each compound in a common vegetable, crowndaisy (Chrysanthemum coronarium L.) seeds alcohol extract (CDAE) without the isolation of monomers. The results of LC–ESI–MS/MS showed that the main components of CDAE were chlorogenic acid (3-CQA) (1693.0 μg/g, dry weight), 1,3-dicaffeoylquinic acid (1,3-DCQA, 1378.5 μg/g), 3,5-DCQA (1027.0 μg/g), and 1,4-DCQA (1031.5 μg/g). The results of scavenging free radical activity analysis showed that, among all components, 1,3-DCQA, 3,5-DCQA, 1,4-DCQA, and 3-CQA were mainly responsible for the radical scavenging activity of the extract. Their scavenging rates for 2,2-diphenyl-1-picrylhydrazyl (DPPH) were 86.72%, 83.50%, 83.50%, and 83.43%, respectively. In the assay of scavenging the reactive oxygen species (ROS), CDAE could effectively decrease ROS in RAW264.7 cells without cell toxicity.