The combined effects of novel tocotrienols and lovastatin on lipid metabolism in chickens

Both lovastatin (a fungal product) and a tocotrienol rich fraction (TRF25, a mixture of tocols isolated from stabilized and heated rice bran containing desmethyl [d-P21-T3] and didesmethyl [d-P25-T3] tocotrienols) are potent hypocholesterolemic agents, although they suppress cholesterol biosynthesis by different mechanisms. To determine additive and/or synergistic effects of both agents, chickens were fed diets supplemented with 50 ppm TRF25 or d-P25-T3 in combination with 50 ppm lovastatin for 4 weeks. Combinations of d-P25-T3 with lovastatin were found most effective in reducing serum total cholesterol and low-density lipoprotein (LDL) cholesterol compared to the control diet or individual supplements. The mixture of TRF25+lovastatin inhibited the activity of β-hydroxy-β-methylglutaryl coenzymeA reductase (21%) compared to lovastatin alone, which did not change its activity. Cholesterol 7α-hydroxylase activity was increased by lovastatin (11%) and by lovastatin plus TRF25 (19%). TRF25+lovastatin decreased levels of serum total cholesterol (22%), LDL cholesterol (42%), apolipoprotein B (13–38%), triglycerides (19%), thromboxane B2 (34%) and platelet factor 4 (26%), although high-density lipoprotein (HDL) cholesterol, and apolipoprotein A1 levels were unaffected. The mixture of TRF25+lovastatin showed greater effects than did the individual treatments alone, reflecting possible additive pharmacological actions. The effects, however, of the d-P25-T3/lovastatin combination were no greater than that of d-P25-T3 alone, possibly indicating that d-P25-T3 produced a maximum cholesterol lowering effect at the concentration used.