Norbixin, a natural dye that improves serum lipid profile in rabbits and prevents LDL oxidation.

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.

Dietary supplementation with annatto food-coloring extracts increases the resistance of human erythrocytes to hemolysis.

Erythrocytes exhibit high susceptibility to hemolysis in several pathologies due to the oxidation of cellular components. We hypothesized that annatto carotenoids improve the redox status of erythrocyte plasma membranes and promote a consequent increase in human erythrocyte resistance to hemolysis. The objective of this study was to evaluate whether food-grade annatto carotenoids can increase human erythrocyte resistance to hemolysis in vitro and ex vivo. For the in vitro experiment, erythrocytes from healthy volunteers were isolated and coincubated with bixin (BIX) or norbixin (NBIX) and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), glucose, or sodium nitrite (NaNO2) as hemolysis inducers. In the ex vivo study, healthy volunteers consumed a capsule containing BIX or NBIX (0.05 mg/kg body weight per day) or placebo for 7 days before blood sample collection. Their erythrocytes were isolated and incubated with AAPH, glucose, or NaNO2. In both the ex vivo and in vitro studies, erythrocytes were subjected to osmotic fragility tests. The activity of antioxidant enzymes, and reduced glutathione and lipid peroxidation levels in erythrocytes were also evaluated ex vivo. In vitro BIX and NBIX not only reduced erythrocyte membrane fragility induced by AAPH, glucose, or NaNO2 but also improved basal osmotic resistance in the micromole-per-liter range (P < .05). BIX and NBIX supplementation increased erythrocyte membrane resistance (P < .05), with BIX being more effective. Also, BIX and NBIX protected erythrocytes from lipid peroxidation and improved the cellular redox environment (P < .05). These results support the hypothesis that annatto carotenoids supplementation exerts antihemolytic properties by preventing the oxidative damage of human erythrocytes.

Short-Term Bixin Supplementation of Healthy Subjects Decreases the Susceptibility of LDL to Cu2+-Induced Oxidation Ex Vivo.

Lycopene-based medications and supplements have been developed to prevent atherosclerosis, primarily because of their ability to decrease low-density lipoprotein (LDL) oxidation. Bixin and norbixin are carotenoids found in the seeds of annatto (Bixa orellana) and are colorants widely used by the food industry. Some studies have already demonstrated that these compounds have antioxidant and antiatherogenic potential in vitro and in animal models, but there is no evidence supporting the effects of their long-term or short-term consumption by humans. The aim of this study was to evaluate the effects of short-term intake of annatto carotenoids on biochemical and oxidative stress biomarkers as well as on the susceptibility of LDL oxidation in healthy individuals, using lycopene as a positive control. The effect of daily supplementation (0.05 mg/kg of body weight (b.w.)) with bixin, norbixin, lycopene, or placebo for 7 days was evaluated in a randomized, controlled crossover study in 16 healthy volunteers (8 men and 8 women). The susceptibility of LDL to Cu2+-induced oxidation ex vivo, biochemical parameters, and oxidative stress biomarkers were evaluated. No treatment affected biochemical parameters or most oxidative stress biomarkers. However, bixin reduced the oxidation rate of the LDL lipid moiety (-275%, p < 0.1) and nitric oxide metabolites (NOx) (-460%, p < 0.1), compared to the placebo group. Moreover, we observed that the changes in these parameters were positively associated, supporting the hypothesis that bixin decreases the susceptibility of LDL to Cu2+-induced oxidation by decreasing NOx levels, probably by downregulating the inducible nitric oxide synthase.

The Hepatoprotective Effect of Jaboticaba Peel Powder in a Rat Model of Type 2 Diabetes Mellitus Involves the Modulation of Thiol/Disulfide Redox State through the Upregulation of Glutathione Synthesis.

Jaboticaba peel powder (JPP) is rich in bioactive compounds, mainly soluble and insoluble polyphenols with great antioxidant properties. The aim of this study is to evaluate the effects of JPP supplementation on the oxidative stress and hepatic damage in a rat model of type 2 diabetes mellitus (T2DM). Diabetic rats received vehicle or JPP at 2.7 (JPP-I), 5.4 (JPP-II), or 10.8 (JPP-III) g/L in drinking water during 8 weeks. JPP-III attenuated hyperglycaemia and dyslipidemia increased by 86% the liver content of nonprotein thiol groups and by 90% the GSH/GSSG ratio by activating glutathione synthesis. Accordingly, JPP supplementation prevented the loss of activity of the sulfhydryl-dependent enzyme δ-aminolaevulinic acid dehydratase and attenuated hepatic injury assessed by the reduction of serum aspartate aminotransferase activity and liver hypertrophy. Our results support that JPP supplementation to T2DM rats decreases hepatic damage most likely by increasing glutathione synthesis and modulating the thiol/disulfide redox balance.

Annatto carotenoids attenuate oxidative stress and inflammatory response after high-calorie meal in healthy subjects.

The aim of this study was to evaluate the effect of annatto carotenoids intake associated to a single high-calorie meal (high fat and high carbohydrate) in postprandial biochemical, inflammatory and oxidative stress markers. Twelve healthy subjects (6 men, 6 women) were included in this randomised, controlled crossover study. Baseline blood samples were collected from fasting subjects that immediately received high-calorie meal without carotenoid (placebo) or containing 1.2mg/kg bixin (BIX) or 0.06mg/kg norbixin (NBIX). Blood samples were taken 60, 120 and 240min after meal intake. NBIX intake did not affect biochemical blood markers but reduced the postprandial levels of inflammatory cytokines (IL-1, IL-6 and TNF-α) and lipid oxidation 60-120min after meal. BIX only partially prevented postprandial-induced lipid oxidation. Results indicate that the intake of NBIX may be an alternative to reduce the postprandial inflammatory and oxidative stress responses to high-calorie meals.

The antiatherogenic effect of bixin in hypercholesterolemic rabbits is associated to the improvement of lipid profile and to its antioxidant and anti-inflammatory effects.

Hypercholesterolemia and oxidative stress have been implicated in the pathophysiology of atherosclerosis and coronary artery disease. We investigated whether the carotenoid bixin (BIX) may reduce oxidative damage, inflammatory response, and the atherosclerotic lesion induced by hypercholesterolemia in rabbits. Rabbits received regular chow (control) or a hypercholesterolemic diet (0.5% cholesterol) alone or supplemented with BIX (10, 30 or 100 mg/kg body weight, b.w.) or simvastatin (15 mg/kg b.w.) for 60 days. Treatment with BIX or simvastatin reduced the atherosclerotic lesions in cholesterol-fed rabbits (up to 55 and 96% reduction, respectively). This protective effect of BIX was accompanied by decrease in the levels of tumor necrosis factor alpha by 15%, interleukin 6 by 19%, lipid peroxidation by 60%, non-high-density lipoprotein cholesterol (non-HDL-C) by 37%, and triglycerides by 41%. BIX increased by 160% the HDL-C levels and decreased by 67% the atherogenic index of hypercholesterolemic rabbits. In atherosclerotic rabbits, the non-protein thiol groups content and the activity of the antioxidant enzymes superoxide dismutase, catalase, glutathione reductase, and thioredoxin reductase were increased in the aortic tissue, whereas paraoxonase activity was reduced in the serum. All these changes were completely prevented by BIX or simvastatin treatment. These results demonstrate that BIX reduces the extent of atherosclerotic lesions and this effect was associated with the decrease in oxidative stress, inflammatory response, and improvement of dyslipidemia, which were most effectively controlled after treatment with 10-30 mg BIX/kg b.w. BIX consumption may, therefore, be an adjuvant to prevent atherosclerosis reducing risk factors for coronary diseases.

Bixin and norbixin have opposite effects on glycemia, lipidemia, and oxidative stress in streptozotocin-induced diabetic rats.

The present study investigated the effects of oral administration of annatto carotenoids (bixin (BIX) and norbixin (NBIX)) on glucose levels, lipid profiles, and oxidative stress parameters in streptozotocin (STZ)-induced diabetic rats. Animals were treated for 30 days in the following groups: nondiabetic control, diabetic vehicle, diabetic 10 mg/kg BIX, diabetic 100 mg/kg BIX, diabetic 10 mg/kg NBIX, diabetic 100 mg/kg NBIX, diabetic metformin, and diabetic insulin. Blood glucose, LDL cholesterol, and triglyceride levels were reduced in the diabetic rats treated with BIX. BIX treatment prevented protein oxidation and nitric oxide production and restored superoxide dismutase activity. NBIX treatment did not change most parameters assessed, and at the highest dose, it increased LDL cholesterol and triglycerides levels and showed prooxidant action (increased protein oxidation and nitric oxide levels). These findings suggested that BIX could have an antihyperglycemic effect, improve lipid profiles, and protect against damage induced by oxidative stress in the diabetic state. Because NBIX is a water-soluble analog of BIX, we propose that lipophilicity is crucial for the protective effect of annatto carotenoids against streptozotocin-induced diabetes.