Flavan derivatives from the fruits of Daemonorops draco Bl. and their protective effects on oxygen-glucose deprivation-induced endothelial cell injury.

Fifteen previously undescribed flavan derivatives (1-15), along with 13 known analogues (5a, 16-24) were isolated from the fruits of Daemonorops draco Bl. Six pairs of isomers (1a/1b, 2a/2b, 3a/3b, 4a/4b, 6a/6b, and 18a/18b) were resolved by using chiral-phase HPLC separation. Their structures were elucidated by spectroscopic data analysis, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Compounds 1a/1b possess an unusual spiro[benzofuran-2,4'-chromen] skeleton, and compounds 2a/2b feature a rare 2,5-methanobenzo[d][1,3]dioxepan moiety in their structures. Compunds 16 and 17 were isolated from a natural source for the first time. All the isolates were evaluated for their protective effects on the human umbilical vein endothelial cells (HUVECs) injury induced by oxygen-glucose deprivation (OGD). Among them, compounds 2a, 2b, 18a, 18b, 20a, 20b, 23, and 24 exhibited significant protection against OGD-induced HUVECs injury. Notably, compound 2b rescued HUVECs from OGD-induced injury by inhibiting apoptosis.