Comparative effects of sesame seeds differing in lignan contents and composition on fatty acid oxidation in rat liver.

We compared the physiological activities of sesame seeds rich in lignans from three varieties (Gomazou, Maruhime and Maruemon), and those from a conventional cultivar (Masekin) in rats. The sum of the values of fat-soluble lignans (sesamin and sesamolin) in seeds of Gomazou, Maruhime and Maruemon varieties was approximately double the value in Masekin. Seeds from Maruemon contained fat-soluble lignan most exclusively as sesamin while other varieties contained sesamin and sesamolin at about a 2:1 ratio. After a 16 d experiment, sesame seeds, added at 200 g/kg to the experimental diets, increased the activity and mRNA levels of fatty acid oxidation enzymes. Increases were stronger with seeds rich in lignans than with seeds from Masekin. In contrast, sesame seeds lowered the activity and mRNA levels of lipogenic enzymes. However, sesame seeds from all the varieties were comparable in affecting these parameters. Serum triacylglycerol concentrations were lower in rats fed diets containing sesame seeds rich in lignans than in those fed a diet free of sesame seeds or a diet containing seeds from the Masekin variety. Serum malondialdehyde (a marker of lipid peroxidation) was lower in rats fed diets containing sesame seeds rich in lignans than in those fed a sesame seed-free diet or Masekin diet. It is apparent that sesame seeds rich in lignans, irrespective of lignan composition, more profoundly affect hepatic fatty acid oxidation and serum triacylglycerol levels and possibly attenuate oxidative stress. Therefore, consumption of sesame seeds rich in lignans hopefully results in physiological activity to promote health.

Combined effect of sesamin and α-lipoic acid on hepatic fatty acid metabolism in rats.

PURPOSE: Dietary sesamin (1:1 mixture of sesamin and episesamin) decreases fatty acid synthesis but increases fatty acid oxidation in rat liver. Dietary α-lipoic acid lowers hepatic fatty acid synthesis. These changes can account for the serum lipid-lowering effect of sesamin and α-lipoic acid. It is expected that the combination of these compounds in the diet potentially ameliorates lipid metabolism more than the individual compounds. We therefore studied the combined effect of sesamin and α-lipoic acid on lipid metabolism in rats. METHODS: Male Sprague-Dawley rats were fed diets supplemented with 0 or 2 g/kg sesamin and containing 0 or 2.5 g/kg α-lipoic acid for 22 days. RESULTS AND CONCLUSIONS: Sesamin and α-lipoic acid decreased serum lipid concentrations and the combination of these compounds further decreased the parameters in an additive fashion. These compounds reduced the hepatic concentration of triacylglycerol, the lignan being less effective in decreasing this value. The combination failed to cause a stronger decrease in hepatic triacylglycerol concentration. The combination of sesamin and α-lipoic acid decreased the activity and mRNA levels of hepatic lipogenic enzymes in an additive fashion. Sesamin strongly increased the parameters of hepatic fatty acid oxidation enzymes. α-Lipoic acid antagonized the stimulating effect of sesamin of fatty acid oxidation through reductions in the activity of some fatty acid oxidation enzymes and carnitine concentration in the liver. This may account for the failure to observe strong reductions in hepatic triacylglycerol concentration in rats given a diet containing both sesamin and α-lipoic acid.