Objective        To determine the effect of total saponin from Rhizoma Panacis majoris on the oxidative stress-induced injuries in neonatal rat cardiomyocytes.       Methods        Neonatal rat cardiomyocytes were

primarily isolated from 1- to 3-day-old Wistar rats and then treated with H

2

O

2

at the IC

50

of 50% to induce Oxidative stress-induced injury. The injuried cells were then treated with the total saponin (100 and 200 μg/ml) for 24 h. The beating rates of cardiomyocytes were observed by inverted microscopy

viability of cells and oxidative stress-induced apoptosis measured by by MTT assay

cell apoptotic rate and ROS content detected by flow cytomety

and apoptosis morphous of cells were observed by hoechst33258 through fluorescence microscopy. The levels of superoxide dismutase (SOD)

glutathione peroxidase (GSH-Px)

hydrogen peroxidase (CAT)

malondialdehyde (MDA)

lactate dehydrogenase (LDH)

and creatine kinase (CK) in the culture medium were also measured. Real-time polymerase chain reaction was applied to detect the mRNA expression of SOD10-SOD3

CAT and GPX1 antioxidative genes

and expression of Nrf2 in the cell cytoplasm and nucleus were detected by Western blotting.       Results        H

2

O

2

at the concentration of 200 to 800 μmol/L significantly inhibited the viability and apoptosis of cells (IC

50

=500 μmol/L). Total saponin from Rhizoma Panacis majoris (100 and 200 μg/ml) significantly increased the beating rates of cardiomyocytes and cell viability (P0.01)

reduced the apoptosis rate

improved apoptosis morphous

decreased intra-cellular ROS contents (P0.01)

improved the activities of SOD

GSH-Px and CAT

and decreased the levels of LDH

CK and MDA (P0.05

P0.01). Moreover

the mRNA expression of SOD1-SOD3

CAT and GPX1 in the cardiomyocytes was decreased remarkably in the model group

while they were up-regulated in total saponin-treatment groups (P0.05

P0.01). The protein expression of Nrf2 in the nucleus were significantly increased compared with model group (P0.05

P0.01) after treatment with the total saponin.       Conclusion        Total saponin from Rhizoma Panacis majoris effectively inhibits oxidative stress-induced injuries of

cardiomyocytes by activating anti-oxidative pathway of Nrf2 and removing ROS.