New naphtoquinones derivatives from the edible bulbs of Eleutherine americana and their protective effect on the injury of human umbilical vein endothelial cells

Abstract

Seven new naphthoquinone derivatives, named eleutherins A-G (1-7), were isolated from the edible bulbs of Eleutherine americana (Hong-Cong), which belongs to the Iridaceae family. Their structures were elucidated on the basis of spectroscopic analysis including high-resolution-electron spray ionization-mass spectrometry (HR-ESI-MS) and 1D and 2D nuclear magnetic resonance (NMR) techniques. The absolute configurations of compounds 1-4 were determined by experimental and calculated data. Additionally, a hypothetical biosynthetic pathway of 1-7 was postulated. All the isolates were evaluated for their protective effect against the injury of human umbilical vein endothelial cells (HUVECs) in vitro. Eleutherins A and B (1-2) showed a potential protective effect on microvessels.

Keywords: Biosynthetic pathway; Eleutherine americana; HUVECs; Iridaceae family; Naphthoquinone derivatives.