Oxidized low-density lipoprotein (oxLDL) inhibits mammalian target of rapamycin (mTOR) and induces autophagy and apoptosis in vascular endothelial cells (VECs) that play very critical roles for the cardiovascular homostasis. We recently defined 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) as a new activator of mTOR. Therefore, we hypothesized that 3BDO had a protective role in VECs and thus stabilized atherosclerotic lesions in apolipoprotein E-/- (apoE-/-) mice. Our results showed that oxLDL inhibited the activity of mTOR and increased the protein level of autophagy-related 13 (ATG13) and its dephosphorylation, thus inducing autophagy in human umbilical vein endothelial cells (HUVECs). All of these effects were strongly inhibited by 3BDO. In vivo experiments confirmed that 3BDO activated mTOR and decreased the protein level of ATG13 in the plaque endothelium of apoE-/- mice. Importantly, 3BDO did not affect the activity of mTOR and autophagy in macrophage cell line RAW246.7 and vascular smooth muscle cells of apoE-/- mice, but suppressed plaque endothelial cell death and restricted atherosclerosis development in the mice. 3BDO protected VECs by activating mTOR and thus stabilized atherosclerotic lesions in apoE-/- mice.

Vascular endothelial cell (VEC) apoptosis is involved in the development of atherosclerosis and other cardiovascular diseases. We previously found that ethyl 1-(2-hydroxy-3-aroxypropyl)-3-aryl-1H-pyrazole -5-carboxylate derivatives (3a-o) play important roles in cell fate control. In this study, among the 15 compounds, we further screened 2 compounds, 3d and 3k, that suppressed VEC apoptosis induced by deprivation of serum and fibroblast growth factor 2. To clarify which chiral enantiomers of 3d and 3k functioned, we synthesized 3d-S and its enantiomer 3d-R, 3k-S, and its enantiomer 3k-R. Then, we investigated the apoptosis-inhibiting activity of the chiral compounds in VECs. Four small molecules, 3d-S, 3d-R, 3k-S, 3k-R, significantly elevated VEC viability and inhibited apoptosis. Furthermore, these small molecules could obviously decrease the level of integrin β4 that plays a key role in the regulation of VEC apoptosis. 3k-S and 3k-R increased Bcl-2/Bax ratio and reduced reactive oxygen species levels dramatically. Therefore, we provide new VEC apoptosis inhibitors. These compounds may be potential agents in the prevention of vascular diseases associated with VEC apoptosis.