Forsythoneosides A–D, Neuroprotective Phenethanoid and Flavone Glycoside Heterodimers from the Fruits of <i>Forsythia suspensa</i>

Abstract

Forsythoneosides A–D (1–4), four unusual adducts of a flavonoid unit fused to a phenylethanoid glycoside through a pyran ring or carbon–carbon bond, and four new phenylethanoid glycosides (5–8) were isolated from the fruits of Forsythia suspensa, together with nine known compounds. The structures of 1–8, including their absolute configurations, were elucidated by spectroscopic data as well as experimental and calculated electronic circular dichroism analysis. Compounds 2 and 4 inhibited PC12 cell damage induced by rotenone, and increased cell viability from 53.9 ± 7.1% to 70.1 ± 4.0% and 67.9 ± 5.2% at 0.1 μM, respectively.