Protective effects of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles on H2O2-induced oxidative stress in HepG2 cells

This work investigated the protective effects of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles (EPS-SeNPs) at different Se/EPS ratios (1/20, 1/3, 1/1, and 4/3) against 0.4 mM H2O2-induced oxidative stress in human hepatoma (HepG2) cells. Results revealed that EPS-SeNPs (0.1-4.0 μg/mL) promoted the proliferation of HepG2 cells with a cell viability of over 90% during H2O2 stress. Different Se/EPS ratios of EPS-SeNPs provided protective effects against H2O2-induced oxidative stress in HepG2 cells by increasing cell viability, restoring cell and nucleus morphology, as well as reducing lactate dehydrogenase (LDH) levels. Particularly, EPS-SeNPs (Se/EPS = 1/1) with the smallest particle size showed the highest cell viability and the greatest inhibitory effect on LDH level. Besides, EPS-SeNPs also inhibited nitric oxide and reactive oxygen species (ROS) production, and increased mitochondrial membrane potential, superoxide dismutase (SOD), and catalase levels while reducing glutathione (GSH) content. Specially, EPS-SeNPs at Se/EPS ratio of 1/3 with smaller size showed the lowest ROS level and the highest antioxidant activities (SOD and GSH), implying that the ROS generation was inhibited by increasing enzymatic and non-enzymatic antioxidants. The enhanced protective effect of EPS-SeNPs (Se/EPS = 1/1 and 1/3) might be attributed to its smaller particle size.