Furanocoumarins from the Roots of Angelica dahurica with Inhibitory Activity against Intracellular Reactive Oxygen Species Accumulation

Five new furanocoumarins, dahuribirin H (1), dahuribirin I (2), (2′S)-(+)-5-(2′-hydroxy-3′-methylbut-3′-enyloxy)-8-(3′′-methylbut-2″-enyloxy)psoralen (3), (2′R)-(+)-5-(2′,3′-epoxy-3′-methylbutoxy)-8-(3″-methylbut-2″-enyloxy)psoralen (4), and 5-methoxy-8-((Z)-4′-(3″-methylbutanoate)-3′-methylbut-2′-enyloxy)psoralen (5), along with 15 known compounds (6-20), were isolated from the roots of Angelica dahurica. The structures of the new compounds were elucidated by spectroscopic analysis, along with electronic circular dichroism calculations and Mosher ester analysis. Compounds 3, 4, 11, 13, and 16 reduced H₂O₂-induced cell death in HepG2 cells and attenuated reactive oxygen species (ROS) formation without showing cytotoxicity, suggesting that these compounds might have cytoprotective effects against H₂O₂-induced oxidative damage via ROS scavenging activities.