In Vitro and In Vivo Effects of Prosomillet and Sorghum on Cholesterol Metabolism

To study the effects of prosomillet and sorghum on cholesterol metabolism, five solvent (hexane, chloroform, ethyl acetate, butanol and water) fractions obtained from methanol extracts of prosomillet (panicum milaceum) and sorghum (sorghum bicolor L Moench) were tested in vitro for their action on 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase. They were added as powder to the high cholesterol diets (0.5%, w/w) at the level of 30% (w/w) of the respective groups of rats. Three kinds of experimental diets, including a control were based on AIN-76 composition and fed for four weeks to male Sprague-Dawley rats weighing $211{\pm}7\;g$. Hexane, chloroform, and ethylacetate fractions from prosomillet and hexane fraction from sorghum inhibited HMG-CoA reductase from rat liver microsome almost completely. Chloroform and ethyl acetate fractions from sorghum exhibited 40 to 60% inhibition. The effects of hexane fractions from both prosomillet and sorghum were shown in a dose-response manner. When the five fractions from each grain were added to the HepG2 cell culture media at a concentration of $20\;{\mu}g/mL$, all the fractions except water reduced the activity of HMG-CoA reductase by 25 up to 80%. However, activities of hepatic HMG-CoA reductase in rats that were fed the two kinds of grain were not significantly different from those of the control group. Nevertheless, the plasma level of total cholesterol was significantly reduced in the sorghum group, and the plasma level of HDL-cholesterol and fecal bile acid excretions increased in both groups. In conclusion, both grains have positive effects on body cholesterol metabolism by increasing cholesterol turnover and also possibly by inhibiting cholesterol synthesis.