We hypothesized that
norbixin, which is a
carotenoid used as an orange/red natural food coloring additive, has anti-atherogenic properties. An in vitro oxidation assay with human
LDL and a rabbit model of
atherosclerosis were used to test this hypothesis.
Norbixin inhibited the oxidation of isolated human
LDL in a concentration-dependent manner. In the in vivo assay, rabbits were fed with a regular chow (control) or an atherogenic diet (0.5%
cholesterol) alone or supplemented with
norbixin (10, 30 or 100 mg/kg b.w.) for 60 days.
Norbixin supplementation (30 and 100 mg/kg b.w.) increased HDL levels and reduced
triglyceride levels and the atherogenic index of rabbits. This effect was associated with the decrease of serum levels of
oxidized LDL,
oxidized LDL antibodies and aortic tissue levels of
lipid and
protein oxidation in the atherogenic rabbits supplemented with
norbixin. Atherogenic diet increased enzymatic (
superoxide dismutase,
catalase,
glutathione reductase, and
thioredoxin reductase-1) and non-enzymatic (non-
protein thiol groups content)
antioxidant defense systems in the aortic tissue but reduced the activity of
paraoxonase-1 in the serum. All these changes were prevented by
norbixin supplementation (10, 30 and 100 mg/kg b.w.). These results suggest that
norbixin has atheroprotective potential by improving serum
lipid profile and preventing oxidative modifications of circulating
LDL and aortic tissue.
Norbixin may, therefore, be beneficial in the control of
atherosclerosis risk factors and can be further investigated as a candidate to be used not only as a functional food ingredient but also for therapeutic applications and in the nutraceutical industry.