Changes in plasma lipid and antioxidant activity in rats as a result of naringin and red grapefruit supplementation.

The aim of this investigation was to compare the influence of naringin versus red grapefruit juice on plasma lipid levels and plasma antioxidant activity in rats fed cholesterol-containing and cholesterol-free diets. The antioxidant activity of a correlated quantity of red grapefruit juice was higher than that of naringin. Forty-two male Wistar rats were randomly divided into six groups of 7 named control, naringin, grapefruit, Chol, Chol/naringin, and Chol/grapefruit. The rats of the control group were fed basal diet (BD) and 1-2 mL of distilled water. To the BD of the other five groups were added 0.46-0.92 mg of naringin dissolved in 1-2 mL of distilled water (naringin), 1-2 mL of red grapefruit juice (grapefruit), 1% of nonoxidized cholesterol (NOC) and 1-2 mL of distilled water (Chol), 1% of NOC and 0.46-0.92 mg of naringin in 1-2 mL of water (Chol/naringin), and 1% of NOC and 1-2 mL of red grapefruit juice (Chol/grapefruit). After 30 days of different feeding, it was found that diets supplemented with red grapefruit juice and to a lesser degree with naringin improved the plasma lipid levels mainly in rats fed cholesterol and increased the plasma antioxidant activity. In conclusion, naringin is a powerful plasma lipid lowering and plasma antioxidant activity increasing flavonone. However, fresh red grapefruit is preferable than naringin: it more effectively influences plasma lipid levels and plasma antioxidant activity and, therefore, could be used as a valuable supplement for disease-preventing diets.

Effect of different olive oils on bile excretion in rats fed cholesterol-containing and cholesterol-free diets.

The mechanism of the hypocholesterolemic effect of olive oils was investigated in 60 Wistar rats adapted to cholesterol-containing and cholesterol-free diets. The rats were divided in six diet groups of 10. The control group was fed only basal diet (BD), which contained wheat starch, casein, cellulose, and mineral and vitamin mixtures. For the five other groups, 10 g/100 g virgin (virgin group) or lampante (lampante group) olive oils, 1 g/100 g cholesterol (chol group), or both cholesterol and oil (chol/virgin and chol/lampante groups) were added to the BD. The experiment lasted 4 weeks. Before and after the experiment the bile was collected, and its flow and biliary bile acids and cholesterol concentrations were registered. Plasma lipids, liver cholesterol, plasma antioxidative potential (TRAP), fecal output, fecal bile acids, and fecal cholesterol excretion were measured. Groups did not differ before the experiment. After the experiment significant hypocholesterolemic and antioxidant effects were registered mainly in groups of rats fed cholesterol-containing diets supplemented with both olive oils (chol/virgin and chol/lampante). Significant increases in the bile flow and in the bile cholesterol and bile acids concentrations were observed (19.2% and 16.9%, 30.5% and 18.2%, and 79.6% and 45.6% for the chol/virgin and chol/lampante groups, respectively). Also, significant increases of the fecal output and fecal excretion of bile acids and cholesterol in rats of these groups were found. In conclusion, olive oils positively affect plasma lipid metabolism. The hypocholesterolemic effect of olive oils is genuine and is most likely mediated through increases in bile flow and biliary cholesterol and bile acids concentrations and subsequent increases in their fecal excretion.

Apple and pear peel and pulp and their influence on plasma lipids and antioxidant potentials in rats fed cholesterol-containing diets.

The aim of this study was to assess the bioactive compounds of apple and pear peel and pulp in vitro and their influence on plasma lipids and antioxidant potentials in vivo. The antioxidant potentials measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), beta-carotene bleaching (beta-carotene), and nitric oxide inhibition radical scavenging (NO) tests in apple peel and pulp were significantly higher than in pear peel and pulp, respectively. The ethanol extract of apple peels showed the strongest inhibition of lipid peroxidation as a function of its concentration and was comparable to the antioxidant activity of butylated hydroxyanisole. The pear pulp extract had the weakest antioxidant ability, whereas other extracts such as apple pulp and pear peel were nearly equal. The antioxidant activities comprised contributions from polyphenols, phenolic acids, and flavonoids and correlated well with polyphenols and flavonoids. The correlation coefficients between polyphenols and antioxidant activities by DPPH, beta-carotene, and NO were as follows: 0.9207, 0.9350, and 0.9453. Contrarily, the correlation coefficient between the content of dietary fiber and the antioxidant activities test was low. The content of all studied indices in apple and pear peel was significantly higher than in peeled fruits (p < 0.05). Diets supplemented with fruit peels exercised a significantly higher positive influence on plasma lipid levels and on plasma antioxidant capacity of rats than diets with fruit pulps.

Fresh Israeli Jaffa blond (Shamouti) orange and Israeli Jaffa red Star Ruby (Sunrise) grapefruit juices affect plasma lipid metabolism and antioxidant capacity in rats fed added cholesterol.

The bioactivity of Israeli Jaffa blond (Shamouti) fresh orange and Israeli Jaffa red Star Ruby (Sunrise) grapefruit juices was investigated in vitro and in vivo. The contents of bioactive compounds of these juices were determined. The influence of bioactive compounds on plasma lipids and plasma antioxidant activity in rats fed cholesterol-containing and cholesterol-free diets was assessed. Significant differences in the contents of dietary fibers were not found. The contents of total polyphenols, flavonoids, and anthocyanins in fresh orange and grapefruit juices were 962.1 +/- 27.2 and 906.9 +/- 27.1; 50.1 +/- 3.3 and 44.8 +/- 3.2; and 69.9 +/- 5.6 and 68.7 +/- 5.5 microg/mL, respectively. The antioxidant potential measured by the scavenging activity against nitric oxide, the beta-carotene-linoleate model system (beta-carotene), and the 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) diamonium salt assays was higher in orange juice but not significantly. A high level of correlation between contents of total polyphenols and flavonoids and antioxidant potential values of both juices was found. Diets supplemented with orange and to a lesser degree with grapefruit juices improved plasma lipid metabolism only in rats fed added cholesterol. However, an increase in the plasma antioxidant activity was observed in both groups. In conclusion, fresh orange and grapefruit juices contain high quantities of bioactive compounds, which guarantee their high antioxidant potential, and the positive influence on plasma lipid metabolism and plasma antioxidant activity could make fresh orange and grapefruit juices a valuable supplement for disease-preventing diets.

Olive oils improve lipid metabolism and increase antioxidant potential in rats fed diets containing cholesterol.

The effect of olive oils on lipid metabolism and antioxidant activity was investigated on 60 male Wistar rats adapted to cholesterol-free or 1% cholesterol diets. The rats were divided into six diet groups of 10. The control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein, cellulose, and mineral and vitamin mixtures. To the BD were added 10 g/100 g virgin (virg group) or Lampante (Lamp group) oils, 1 g/100 g cholesterol (chol group), or both (chol/virg group) and (chol/Lamp group). The experiment lasted 4 weeks. Plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), total phospholipids (TPH), HDL-phospholipids (HDL-PH), total radical-trapping antioxidative potential (TRAP), malondialdehyde lipid peroxidation (MDA), and liver TC were measured. Groups did not differ before the experiment. In the chol/virg and chol/Lamp vs chol group, the oil-supplemented diets significantly (P < 0.05) lessened the increase in plasma lipids due to dietary cholesterol as follows: TC (25.1 and 23.6%), LDL-C (39.3 and 34.7%), TG (19.3 and 17.0%), and TC in liver (36.0 and 35.1%) for the chol/virg and chol/Lamp group, respectively. The chol/virg and chol/Lamp diets significantly decreased the levels of TPH (24.7 and 21.2%; p < 0.05 in both cases) and HDL-PH (22.9 and 18.0%; p < 0.05 in both cases) for the chol/virg and chol/Lamp group, respectively. Virgin and Lampante oils in rats fed basal diet without cholesterol did not affect the lipid variables measured. Virgin, and to a lesser degree Lampante, oils have increased the plasma antioxidant activity in rats fed BD without cholesterol (an increase in TRAP, 20.6 and 18.5%; and a decrease in MDA, 23.2 and 11.3%, respectively). In the rats of chol/virg and chol/Lamp vs Chol diet groups the added oils significantly hindered the decrease in the plasma antioxidant activity (TRAP, 21.2 and 16.7%; and MDA, 27.0 and 22.3%, respectively). These results demonstrate that virgin, and to less degree Lampante, oils possess hypolipidemic and antioxidant properties. It is more evident when these oils are added to the diets of rats fed cholesterol. These positive properties are attributed mostly to the phenolic compounds of the studied oils.