Neuroprotective Caffeoylquinic Acid Derivatives from the Flowers of Chrysanthemum morifolium

Three new caffeoylquinic acid derivatives, chrysanthemorimic acids A–C (1–3), and 11 known compounds (4–14) were isolated and characterized from the flowers of Chrysanthemum morifolium. Their structures were confirmed by spectroscopic data as well as by comparison of the experimental and calculated electronic circular dichroism spectra. Chrysanthemorimic acids A–C possess a rare 8-oxa-bicyclo[3.2.1]­oct-3-en-2-one ring that is formed through a [5+2] cycloaddition of caffeoylquinic acid with a d-glucose derivative. Compounds 1–3, 6–8, 12, and 13 displayed significant effects against hydrogen peroxide-induced neurotoxicity in SH-SY5Y cells at 10 μM.