抄録
The hypocholesterolemic activities of phytosterols and related compounds were compared in rats receiving a 3%-cholesterol containing diet. The rats were intravenously injected for 5 days with emulsions of saline-albumin containing each sterol. The greatest effect on lowering liver cholesterol, triglyceride and fatty acids-levels was shown by stigmasterol, followed by β-sitosterol, stigmastanol, ergosterol and 7-ketocholesterol. On the other hand, esters of stigmasterol, such as palmitate and stearate showed considerably lower activity than free stigmasterol. No effect could be seen in stigmasterol acetate, which is not found in nature. Also, the decrease of liver cholesterol by treatment with phytosterols depended on its esterified form. After injection, stigmasterol in liver was present mainly in a free form and the palmitate or the stearate changed partly to the free form, 20% or 25% of the injected amount, respectively. However, stigmasterol acetate remained unchanged after injection. Cytochrome P-450 content of hepatic microsome from hypercholesterolemic rats was significantly decreased by treatment with stigmasterol, and similar findings were obtained in microsomes from livers of normal or phenobarbital-treated rats which had been given stigmasterol. The results suggest that the presence of a free hydroxy group at the C-3 position in phytosterols is necessary for the hypocholesterolemic activities and a double bond at the C-5 position and a side-chain at the C-17 position, may also relate to these activities.
