Palm Tocotrienol-Rich Fraction Protects Neonatal Rat Cardiomyocytes from H2o2-Induced Oxidative Damage

Abstract

Oxidative stress plays an important role in the pathogenesis of heart disease. Tocotrienol-rich fraction (TRF) is an antioxidant and that has the potential to reduce the risk of heart disease. This study is to determine the protective effects of palm TRF against H2O2-induced oxidative damage in neonatal rat cardiomyocytes (NRCM). The NRCM were divided into control, treated with TRF (10 µg/mL), H2O2 (0.5 mM) and treated with TRF prior to H2O2 induction (pre-treatment). Cell viability was determined by the MTS assay,while the presence of reactive oxygen species (ROS) was determined using fluorescent dihydroethidium (DHE) and 5-(and-6)-carboxy-2′,7′-dichlorodihydrofluorescein diacetate (carboxy-H2DCFDA) dye. Mitochondrial integrity and cell death were determined using JC-1 and Annexin V-FITC staining, respectively. Lactate dehydrogenase (LDH) and superoxide dismutase (SOD) activity were determined by colorimetric assay kit. The concentration of H2O2 from 0.5 to 5 mM reduced the cell viability and the H2O2 IC50 value of 0.5 mM was used in the experiment. H2O2 induction increased the intensity of carboxy-H2DCFDA and DHE-stains; and also the intensity of green fluorescence of J-monomers in JC-1 staining compared to the control group. The activity of LDH increased while the activity of SOD decreased in the H2O2 group. Pre-treatment with TRF reduced the intensities of carboxy-H2DCFDA and DHE-stains, as well as the green fluorescence of J-monomers in JC-1. Meanwhile, the LDH activity was reduced in the pre-treatment group but no changes were recorded in SOD activity compared to the H2O2 group. Palm TRF protects cardiomyocytes from oxidative damage by reducing ROS production and maintaining the mitochondrial membrane integrity thus reducing cell death.