Dietary tocotrienols reduce concentrations of plasma cholesterol, apolipoprotein B, thromboxane B2, and platelet factor 4 in pigs with inherited hyperlipemias

Abstract

Normolipemic and genetically hypercholesterolemic pigs of defined lipoprotein genotype were fed a standard diet supplemented with 50 micrograms/g tocotrienol-rich fraction (TRF) isolated from palm oil. Hypercholesterolemic pigs fed the TRF supplement showed a 44% decrease in total serum cholesterol, a 60% decrease in low-density-lipoprotein (LDL)-cholesterol, and significant decreases in levels of apolipoprotein B (26%), thromboxane-B2 (41%), and platelet factor 4 (PF4; 29%). The declines in thromboxane B2 and PF4 suggest that TRF has a marked protective effect on the endothelium and platelet aggregation. The effect of the lipid-lowering diet persisted only in the hypercholesterolemic swine after 8 wk feeding of the control diet. These results support observations from previous studies on lowering plasma cholesterol in animals by tocotrienols, which are naturally occurring compounds in grain and palm oils and may have some effect on lowering plasma cholesterol in humans.

Effects of adding tocotrienol-tocopherol mixed fraction and vitamin C on inflammatory status in hypercholesterolaemic patients in the low coronary risk category

“…One study suggested that tocopherol has a negative impact on the lipid lowering property of tocotrienols (Qureshi et al, 1995), via its stimulating effect on HMG-CoA reductase, the rate-limiting enzyme in the cholesterol synthesis pathway, thus attenuating the inhibitory effect exerted by tocotrienols (Qureshi et al, 1996). It was determined that in a mixed preparation of tocotrienol and tocopherol, 20% or more of the latter leads to attenuation of the former's hypocholesterolaemic effects (Qureshi et al, 1995;Qureshi et al, 1991). …”

Tocotrienols and its impact in cardiovascular health

“…Evidence that the Tocotrienol-Rich Fraction (TRF) of palm oil may indeed lower plasma cholesterol in mammals came from a study of normolipemic and genetically hypercholesterolemic pigs of defined lipoprotein genotype. 40 The pigs were fed a standard diet supplemented with 50 micrograms/g TRF isolated from palm oil. Hypercholesterolemic pigs fed the TRF supplement showed a 44% decrease in total serum cholesterol, a 60% decrease in LDL-cholesterol, and significant decreases in levels of apolipoprotein B (26%), thromboxane-B2 (41%), and platelet factor 4 (PF4; 29%).…”

Multifaceted role of tocotrienols in cardioprotection supports their structure: function relation

“…Theriault et al (1999) studied the effect of c-tocotrienol on apoB synthesis, degradation, and secretion in human hepatocellularcarcinoma cell line (HepG2) which revealed that the presence of c-tocotrienol in the cells stimulates apoB degradation, and it is speculated that the lack of cholesterol availability reduces the number of secreted apoB-containing lipoprotein particles by limiting translocation of apoB into the endoplasmic reticulum lumen. Several epidemiological studies have shown that tocotrienols reduce the atherogenic apoB plasma levels significantly by 10-15% (Qureshi et al 1991a(Qureshi et al , 1995Qureshi and Peterson 2001). A case-controlled study (Qureshi et al 1995) showed that a novel tocotrienol-rich fraction (TRF) from specially processed rice bran oil enriched with didesmethyl-tocotrienol, an isoform of tocotrienols with no methyl groups on the chromanol ring was shown to decrease plasma lipoprotein ''a'' levels by 17%.…”

“…Qureshi et al (1996) observed that plasma cholesterol lowering by tocotrienol-rich extracts in chicken and rat was associated with decreased levels of hepatic HMG-CoA reductase activity. Hypercholesterolemic pigs fed the tocotrienol-rich fraction supplement showed a 44% decrease in total serum cholesterol, a 60% decrease in LDL cholesterol, and significant decreases in levels of apolipoprotein B (26%), thromboxane B2 (41%), and platelet factor 4 (PF4; 29%) (Qureshi et al 1991a). In isolated human liver cells, a-tocotrienol (10 mM for 4 h) inhibited cholesterol synthesis by 32%.…”