This study investigated the effects of a tocotrienol-rich fraction (TTRF) on the microscopic development of atherosclerosis and lipid peroxidation in the aorta of rabbits. Group 1 was fed a normal diet, group 2 received a 2% cholesterol diet and group 3 received a 2% cholesterol diet plus daily oral administration of the TTRF. After 10 weeks, the aortic content of malondialdehyde (MDA) was measured as an index of lipid peroxidation. The MDA was lowest in rabbits that received the TTRF compared to the groups that did not. The degree of intimal thickening was higher in the cholesterol-fed rabbits without the TTRF compared to the cholesterol-fed rabbits with TTRF (P<0.05). The continuity of the internal elastic lamina (IEL) was noted to be preserved in the cholesterol-fed rabbits with TTRF but appeared disrupted in the cholesterol-fed rabbits without the TTRF. The disrupted and fragmented IEL may have resulted from the injury caused by lipid peroxidation that contributed to the more extensive intimal thickening. We conclude that the antioxidant activities of the TTRF can reduce experimental atherosclerosis.
The present study aims to examine the effects of a palm-oil-derived vitamin E mixture containing tocotrienol (approximately 70%) and tocopherol (approximately 30%) on plasma lipids and on the formation of atherosclerotic plaques in rabbits given a 2% cholesterol diet. Eighteen New Zealand White rabbits (2.2-2.8 kg) were divided into three groups; group 1 (control) was fed a normal diet, group 2 (AT) was fed a 2% cholesterol diet and group 3 (PV) was fed a 2% cholesterol diet with oral palm vitamin E (60 mg/kg body weight) given daily for 10 weeks. There were no differences in the total cholesterol and triacylglycerol levels between the AT and PV groups. The PV group had a significantly higher concentrations of HDL-c and a lower TC/HDL-c ratio compared to the AT group (P < 0.003). The aortic tissue content of cholesterol and atherosclerotic lesions were comparable in both the AT and PV groups. However, the PV group had a lower content of plasma and aortic tissue malondialdehyde (P < 0.005). Our findings suggest that despite a highly atherogenic diet, palm vitamin E improved some important plasma lipid parameters, reduced lipid peroxidation but did not have an effect on the atherosclerotic plaque formation.