New Naphthalene Derivatives from the Bulbs of Eleutherine americana with Their Protective Effect on the Injury of HUVECs

Five new naphthalene derivatives, named Eleutherols A–C (1–3) and Eleuthinones B–C (4,5), together with three known compounds were isolated from the bulbs of Eleutherine americana. Their structures were elucidated on the basis of spectroscopic analysis including HR-ESI-MS, 1D and 2D NMR techniques. These compounds exhibited a potent effect against the injury of human umbilical vein endothelial cell (HUVECs) induced by high concentrations of glucose in vitro