Tocotrienols inhibit liver HMG CoA reductase activity in the guinea pig

Abstract

Male guinea pigs were treated intraperitoneally with different dosages of tocotrienols isolated from palm oil fatty acid distillate (PFAD) for 6 consecutive days. Control animals were treated with vitamin E-free palm oil triglycerides. Commercial animal pellets and water were given ad libitum during the treatment period. The guinea pigs were sacrificed at around 2400 hr. Liver HMG CoA reductase was assayed by a combination of conventional TLC and liquid scintillation spectrophotometry using 14C-HMG CoA as the substrate. Our results show that tocotrienols isolated from PFAD inhibited liver HMG CoA reductase activity in the guinea pig and the inhibitory effect of tocotrienols on HMG CoA reductase appeared to be dose-dependent. Analysis of the serum tocol profiles indicate that only α-tocopherol was found in the serum and there was no tocotrienol in the serum after 6 consecutive treatments with tocotrienols. These results indicate a rapid clearance of tocotrienols from the blood circulation. On the contrary, the liver retained much of the tocotrienols administered. The levels of tocotrienols in the liver appear to increase with increased dosages of tocotrienols in the treatment.