Açai (Euterpe oleracea Mart.) dietary intake affects plasma lipids, apolipoproteins, cholesteryl ester transfer to high-density lipoprotein and redox metabolism: A prospective study in women.

The açai fruit (Euterpe oleracea Martius), which is native to the Brazilian Amazon region, was shown to have high polyphenols and MUFA contents. In this study, we aimed to assess the effects of açai consumption on plasma lipids, apolipoproteins, the transfer of lipids to HDL (which is a relevant HDL function), and some biomarkers of redox metabolism. Forty healthy volunteer women aged 24 ± 3 years consumed 200 g of açai pulp/day for 4 weeks; their clinical variables and blood sample were obtained before and after this period. Açai pulp consumption did not alter anthropometric parameters, systemic arterial pressure, glucose, insulin and total, LDL and HDL cholesterol, triglycerides and apolipoprotein (apo) B, but it did increase the concentration of apo A-I. Açai consumption decreased the ROS, ox-LDL and malondialdehyde while increasing the activity of antioxidative paraoxonase 1. Overall, the total antioxidant capacity (TAC) was increased. Regarding the transfer of plasma lipids to HDL, açai consumption increased the transfer of cholesteryl esters (p = 0.0043) to HDL. Unesterified cholesterol, phospholipids and triglyceride transfers were unaffected. The increase in apo A-I and the cholesteryl ester transfer to HDL after the açai intake period suggests that an improvement in the metabolism of this lipoprotein occurred, and it is well known that HDL is protective against atherosclerosis. Another important finding was the general improvement of the anti-oxidant defences elicited by açai consumption. Our data indicate that açai has favourable actions on plasma HDL metabolism and anti-oxidant defence; therefore açai could have a beneficial overall role against atherosclerosis, and it is a consistently good candidate to consider as a functional food.

Açai (Euterpe oleracea Mart.) pulp dietary intake improves cellular antioxidant enzymes and biomarkers of serum in healthy women.

OBJECTIVES: The aim of the present study was to evaluate the effect of açai pulp (Euterpe oleracea Martius) intake on the prevention of oxidative damage by measuring the activity of antioxidant enzymes and biomarkers of protein oxidation in women. METHODS: A nutritional intervention study was conducted with thirty-five healthy women who were asked to consume 200 g/d of açai pulp for 4 wk. Blood samples were collected, and blood pressure and anthropometric parameters were measured before and after the experimental period. Antioxidant enzymes, superoxide dismutase, catalase, glutathione, production of reactive oxygen species, and total antioxidant capacity were evaluated in polymorphonuclear cells. Serum concentration of protein carbonyl and sulfhydryl groups were also determined. RESULTS: The açai intake increased catalase activity, total antioxidant capacity, and reduced the production of reactive oxygen species. Furthermore, it reduced serum concentration of protein carbonyl and increased total serum sulfhydryl groups. CONCLUSIONS: These results show the antioxidant benefit of dietary açai for the healthy women included in the present study, and may increase understanding of the beneficial health properties of this fruit.

High dietary salt decreases antioxidant defenses in the liver of fructose-fed insulin-resistant rats.

In this study we investigated the hypothesis that a high-salt diet to hyperinsulinemic rats might impair antioxidant defense owing to its involvement in the activation of sodium reabsorption to lead to higher oxidative stress. Rats were fed a standard (CON), a high-salt (HS), or a high-fructose (HF) diet for 10 weeks after which, 50% of the animals belonging to the HF group were switched to a regimen of high-fructose and high-salt diet (HFS) for 10 more weeks, while the other groups were fed with their respective diets. Animals were then euthanized and their blood and liver were examined. Fasting plasma glucose was found to be significantly higher (approximately 50%) in fructose-fed rats than in the control and HS rats, whereas fat liver also differed in these animals, producing steatosis. Feeding fructose-fed rats with the high-salt diet triggered hyperinsulinemia and lowered insulin sensitivity, which led to increased levels of serum sodium compared to the HS group. This resulted in membrane perturbation, which in the presence of steatosis potentially enhanced hepatic lipid peroxidation, thereby decreasing the level of antioxidant defenses, as shown by GSH/GSSG ratio (HFS rats, 7.098±2.1 versus CON rats, 13.2±6.1) and superoxide dismutase (HFS rats, 2.1±0.05 versus CON rats, 2.3±0.1%), and catalase (HFS rats, 526.6±88.6 versus CON rats, 745.8±228.7 U/mg ptn) activities. Our results indicate that consumption of a salt-rich diet by insulin-resistant rats may lead to regulation of sodium reabsorption, worsening hepatic lipid peroxidation associated with impaired antioxidant defenses.

The hypocholesterolemic activity of açaí (Euterpe oleracea Mart.) is mediated by the enhanced expression of the ATP-binding cassette, subfamily G transporters 5 and 8 and low-density lipoprotein receptor genes in the rat.

Previous studies have demonstrated that the ingestion of açaí pulp can improve serum lipid profile in various animal models; therefore, we hypothesized that açaí pulp (Euterpe oleracea Mart.) may modulate the expression of the genes involved in cholesterol homeostasis in the liver and increase fecal excretion, thus reducing serum cholesterol. To test this hypothesis, we analyzed the expression of 7α-hydroxylase and ATP-binding cassette, subfamily G transporters (ABCG5 and ABCG8), which are genes involved with the secretion of cholesterol in the rat. We also evaluated the expression of sterol regulatory element-binding protein 2, 3-hydroxy-3-methylglutaryl CoA reductase, low-density lipoprotein receptor (LDL-R), and apolipoprotein B100, which are involved in cholesterol biosynthesis. Female Fischer rats were divided into 4 groups: the C group, which was fed a standard AIN-93 M diet; the CA group, which was fed a standard diet supplemented with 2% açaí pulp; the H group, which was fed a hypercholesterolemic diet (25% soy oil and 1% cholesterol); and the HA group, which was fed a hypercholesterolemic diet supplemented with 2% açaí pulp. At the end of the experimental period, the rats were euthanized, and their blood and livers were collected. The HA group exhibited a significant decrease in serum total cholesterol, low-density lipoprotein cholesterol, and atherogenic index and also had increased high-density lipoprotein cholesterol and cholesterol excretion in feces compared with the H group. In addition, the expression of the LDL-R, ABCG5, and ABCG8 genes was significantly increased by the presence of açaí pulp. These results suggest that açaí pulp promotes a hypocholesterolemic effect in a rat model of dietary-induced hypercholesterolemia through an increase in the expression of ATP-binding cassette, subfamily G transporters, and LDL-R genes.

Salt overload in fructose-fed insulin-resistant rats decreases paraoxonase-1 activity.

Paraoxonase 1 (PON1) is a HDL-associated esterase/lactonase and its activity is inversely related to the risk of cardiovascular diseases. The aim of the present study was to evaluate the effect of a high-salt diet on serum PON1 activity in fructose-fed insulin-resistant rats. Adult male Fischer rats were initially divided into two groups. Control (CON), which received a normal salt diet and drinking water throughout the study; high fructose (HF), which received a normal salt diet and 20% fructose supplemented drinking water. After 10 weeks, half of the animals from HF group were randomly switched to a high-salt diet and 20% fructose supplemented drinking water (HFS) for more 10 weeks. Serum PON1 activity was determined by synthetic substrate phenyl acetate. HFS rats showed markedly decreased PON1 activity (HFS rats, 44.3 ± 14.4 g/dL versus CON rats, 64.4 ± 13.3 g/dL, P < 0.05) as compared to controls. In parallel, the level of oxidative stress, as indicated by thiobarbituric acid reactive substances (TBARS), was increased in HFS rats by 1.2-fold in the liver in relation to controls and was negatively correlated with PON activity. Differential leukocyte counts in blood showed a significant change in lymphocytes and monocytes profile. In conclusion, these results show that PON1 activity is decreased in fructose-fed insulin-resistant rats on a high-salt diet, which may be associated with increased oxidative stress, leading to inflammation.

Diet supplementation with acai (Euterpe oleracea Mart.) pulp improves biomarkers of oxidative stress and the serum lipid profile in rats.

OBJECTIVE: We investigated the antioxidant potential and hypocholesterolemic effects of acai (Euterpe oleracea Mart.) pulp ingestion in rats fed a standard or hypercholesterolemic diet. METHODS: Female Fischer rats were fed a standard AIN-93 M diet (control) or a hypercholesterolemic diet that contained 25% soy oil and 1% cholesterol. The test diet was supplemented with 2% acai pulp (dry wt/wt) for control (group CA) and hypercholesterolemic rats (group HA) for 6 wk. At the end of the experimental period, rats were sacrificed and the blood and livers were collected. To evaluate the effect of acai consumption, levels of protein carbonyl and sulfhydryl groups, superoxide dismutase and paraoxonase activities, and lipid profiles of the sera were measured. RESULTS: Animals that were fed the hypercholesterolemic diet presented increased levels of total and non-high-density lipoprotein cholesterol and decreased levels of high-density lipoprotein cholesterol. Supplementing the diet of this group with acai caused a hypocholesterolemic effect by reducing total and non-high-density lipoprotein cholesterol. Serum levels of carbonyl proteins and total, free, and protein sulfhydryl groups were reduced by acai ingestion in animals receiving the standard or hypercholesterolemic diet. Acai supplementation induced a significant reduction in superoxide dismutase activity only in the hypercholesterolemic rats, indicating an association between diet and acai treatment. Also, acai supplementation increased paraoxonase activity in the CA and HA groups. CONCLUSION: These results suggest that the consumption of acai improves antioxidant status and has a hypocholesterolemic effect in an animal model of dietary-induced hypercholesterolemia.