Inhibition of cholesterol and fatty acid biosynthesis in liver enzymes and chicken hepatocytes by polar fractions of garlic

Different concentrations of polar fractions, methanol‐soluble (MESF), or water‐soluble (WASF), of 1–8% equivalent to fresh garlic paste were added to yellow corn‐soybean based diets and fed to 5‐week‐old male broiler chickens for 3 weeks to measure the inhibition of hepatic β‐hydroxy‐β‐methylglutaryl coenzyme A (HMG‐CoA) reductase, cholesterol 7α‐hydroxylase (7α‐hydroxy) and fatty acid synthetase (FAS). Dose‐related decreases in the activities of these enzymes were obtained. Decreases in serum total cholesterol and in low density lipoprotein (LDL) levels were also observed. There was no effect on the level of cholesterol in high density lipoprotein (HDL). The most effective dose for these decreases was found 0.54% (MESF) and 1.2% (WASF) equivalent to 6% of the fresh garlic. The inhibition of HMG‐CoA reductase and FAS by 25–300 μm of MESF or WASF for 15 min was tested in vitro, in male and female chicken hepatocytes. Inhibitions of activity were dose‐dependent and the degree of inhibition increased with duration of incubation (150 μg of MESF or WASF 5 to 60 min). Dietary supplementation of odorless WASF of garlic was found to be very effective in lowering the total and LDL cholesterol levels compared to control chickens.