Influence of norbixin on plasma cholesterol-associated lipoproteins, plasma arylesterase/paraoxonase activity and hepatic lipid peroxidation of Swiss mice on a high fat diet

Effects of the carotenoid norbixin (7.7 and 92.8 mg/kg) added to drinking water were studied in male Swiss mice fed with a high fat diet for 4 weeks. High fat diet decreased, by 55.7%, the levels of high-density lipoprotein (HDL)-cholesterol (P < 0.05) increased, by 167%, the levels of very low-density lipoprotein (VLDL)-cholesterol/low-density lipoprotein (LDL)-cholesterol (P < 0.0001). When the high fat diet was ingested with norbixin, HDL-cholesterol and VLDL/LDL-cholesterol remained near control levels while plasma triglycerides were not altered. High fat diet decreased the activity of plasma arylesterase/paraoxonase (EC3.1.8.1) by 46% (P < 0.0001), a reduction that was also counteracted by norbixin. Basal levels of thiobarbituric acid-reactive substances (TBARS), measured in liver homogenates, were not increased by high fat diet. However, there was a significant increase in TBARS levels (P < 0.001) when liver homogenate from mice submitted to high fat diet was incubated with Fe2+ and H2O2. Under the same oxidative conditions, liver homogenate was much less responsive to peroxidation (P < 0.0001) when high fat diet was associated with norbixin. Thus, norbixin, a common carotenoid food additive, alters plasma lipid levels and paraoxonase activities in Swiss mice fed with an atherogenic diet. Further studies should be performed in order to determine the lowest effective norbixin concentration as this carotenoid is ingested with industrialized food in very tiny amounts.