Rhizoma Dioscoreae Nipponicae polysaccharides protect HUVECs from H2O2-induced injury by regulating PPARγ factor and the NADPH oxidase/ROS-NF-κB signal pathway.

Objective: Polysaccharides were extracted from Rhizoma Dioscoreae Nipponicae to investigate whether Rhizoma Dioscoreae Nipponicae polysaccharides (RDNP) can act as an antioxidant and PPARγ agonist to protect HUVECs from H2O2-induced injury.

Methods: HUVECs (human umbilical vein endothelial cells) were treated with RDNP in the presence/absence of H2O2. Kits and Fenton reaction were used to produce free radicals. Reagent kits of LDH, MDA, SOD, T-AOC and GSH-Px were used to evaluate the cell injuries and the antioxidant activity of RDNP. Intracellular reactive oxygen species (ROS) generation was detected by 2', 7'-dichlorofluorescein diacetate (DCFH-DA). Western blot was used to evaluate the protein expression of Nox4, p22phox, NF-κB/p65, phospho-NF-κB/p65, IκB as well as PPARγ, ICAM-1 and VCAM-1. Real time quantitative reverse transcriptive polymerase chain reaction (qRT-PCR) was used to confirm the expressions of Nox4, p22phox, ICAM-1 and VCAM-1 mRNA.

Results: RDNP inhibited the production of superoxide anion radical, hydroxyl radical and the lipid peroxidation both in hepatic cells and red blood cells (RBC). It also reduced LDH and MDA levels and enhanced intracellular SOD, T-AOC as well as GSH-Px activities in H2O2-treated HUVECs. Furthermore, RDNP could inhibit ROS generation, Nox4, p22phox, NF-κB/p65, phospho-NF-κB/p65, ICAM-1 and VCAM-1 expression, and it could also inhibit IκB degradation and activate PPARγ expression in HUVECs.

Conclusions: RDNP could protect HUVECs from H2O2-induced injury through interfering PPARγ-NADPH oxidase/ROS-NF-κB pathway. This study will provide new pharmacological evidence that RDNP has positive significance for prevention and treatment of atherosclerosis (AS).