抄録
Hypolipidemic effects of the usual γ-oryzanol (γ-OZ) and a new γ-OZ (N-γ-OZ) with a different sterol composition from γ-OZ were investigated on the hyperlipidemia induced by ingestion of a high cholesterol diet (HCD) containing 1 % cholesterol for 12 days in male Sprague-Dawley rats. Treatment with γ-OZ for 6 days significantly inhibited the increase in serum total cholesterol (TC) and phospholipids (PL) induced by HCD, while the treatment with γ-OZ for 12 days did not inhibit the increase of TC and PL. Treatment with N-γ-OZ at 100 or 1000 mg/kg for 6 days slightly inhibited the increase of TC by HCD. The decrease of TC in high density lipoprotein (HDL-TC) was markedly inhibited by treatment with N-γ-OZ for 12 days, but N-γ-OZ for 6 days and γ-OZ for 6 and 12 days did not inhibit the decrease of HDL-TC. Treatment with N-γ-OZ for 12 days significantly inhibited the increase of PL and free cholesterol (FC) by HCD. γ-OZ at 1000 mg/kg for 12 days also inhibited the increase of FC. N-γ-OZ significantly reduced the atherogenic index using TC and HDL-TC by affecting the HDL-TC increase. γ-OZ at 100 mg/kg and N-γ-OZ at 100 mg/kg for 6 days reduced the atherogenic index using TC and HDL-TC by the inhibition of TC increase. The atherogenic index using PL and HDL-PL was only reduced by the treatment with N-γ-OZ at 1000 mg/g for 12 days. The increase of triglyceride (TG) by HCD was inhibited by the treatment of N-γ-OZ for 6 days (all doses) and 12 days (500, 1000 mg/kg), and γ-OZ at 500 mg/kg for 6 and 12 days also inhibited the increase of TG by HCD. γ-OZ and N-γ-OZ had no effects on liver lipid contents. The hypolipidemic effect of N-γ-OZ was slightly more potent than that of γ-OZ. The inhibition of decrease in HDL-TC and increase in FC by HCD in the treatment with N-γ-OZ was more potent than that of γ-OZ, and these effects of N-γ-OZ may be related to the acceleration of HDL function in the serum.
