Apple phlorizin supplementation attenuates oxidative stress in hamsters fed a high‐fat diet

Phlorizin from apple peel has been used as a nutrient for more than 100 years. The present study investigated the effects of phlorizin on the antioxidant capacity and the antioxidative mechanisms in hamsters fed high‐fat diet supplemented with phlorizin (0.3, 0.6, and 0.9%). Results showed that phlorizin increased the antioxidant enzyme activities and reduced the malondialdehyde content in plasma, liver, heart, and kidney that might arise from the higher mRNA levels of CuZn‐superoxide dismutase, Mn‐superoxide dismutase (Mn‐SOD), catalase, glutathione peroxidase, nuclear factor erythroid 2‐related factor 2‐like (Nrf2), and the protein expression of Mn‐SOD (p < .05). Diet supplemented with phlorizin also significantly decreased the total cholesterol and triglycerides levels in plasma. The present study demonstrated that phlorizin might reduce lipid peroxidation and protect against cardiovascular issues in vivo.

Practical applications

Phlorizin, from apple peel, has been used as a nutrient for over 100 years. To date, despite extensive research on phlorizin, a report on its effect on lipid peroxidation, the antioxidant system in plasma, heart, liver, and kidney of hamsters fed high‐fat diet is yet lacking. This report demonstrates that phlorizin can reduce lipid peroxidation and exert a protective effect on cardiovascular issues in vivo, which is valuable in the rational utilization of phlorizin in functional foods.     

Consumption of barley β‐glucan ameliorates fatty liver and insulin resistance in mice fed a high‐fat diet

Consumption of a diet high in barley β‐glucan (BG) has been shown to prevent insulin resistance. To investigate the mechanism for the effects of barley BG, three groups of male 7‐wk‐old C57BL/6J mice were fed high‐fat diets containing 0, 2, or 4% of barley BG for 12 wk. The 2% BG and 4% BG groups had significantly lower body weights compared with the 0% BG group. The 4% BG group demonstrated improved glucose tolerance and lower levels of insulin‐resistance index and glucose‐dependent insulinotropic polypeptide. Consumption of the BG diet decreased hepatic lipid content. Mice on the BG diet also demonstrated decreased fatty acid synthase and increased cholesterol 7α‐hydroxylase gene expression levels. The BG diet promoted hepatic insulin signaling by decreasing serine phosphorylation of insulin receptor substrate 1 and activating Akt, and it decreased mRNA levels of glucose‐6‐phosphatase and phosphoenolpyruvate carboxykinase. In summary, consumption of BG reduced weight gain, decreased hepatic lipid accumulation, and improved insulin sensitivity in mice fed a high‐fat diet. Insulin signaling enhanced due to the expression changes of glucose and lipid metabolism genes by BG consumption. Consumption of barley BG could be an effective strategy for preventing obesity, insulin resistance, and the metabolic syndrome.     

Effect of hesperidin and naringin on the plasma lipid profile and plasma antioxidant activity in rats fed a cholesterol‐containing diet

The objective of this study was to compare the influence of hesperidin and naringin, the main flavonones of orange and grapefruit, on plasma lipid profile and antioxidant activity in rats fed a cholesterol‐containing diet. Sixty male Wistar rats were randomly divided into six groups of 10, named Control, Hesperidin, Naringin, Chol, Chol/Hesperidin and Chol/Naringin. The Control group was fed a basal diet (BD) and 1–2 mL of distilled water. To the BD of the other five groups were added 0.1–0.2 mg of hesperidin dissolved in 1–2 mL of distilled water (Hesperidin group), 0.46–0.92 mg of naringin in 1–2 mL of water (Naringin group), 1% of non‐oxidised cholesterol (NOC) and 1–2 mL of water (Chol), 1% of NOC and 0.1–0.2 mg of hesperidin in 1–2 mL of water (Chol/Hesperidin), 1% of NOC and 0.46–0.92 mg of naringin in 1–2 mL of water (Chol/Naringin). After 30 days of the experiment it was found that the diets supplemented with hesperidin and naringin increased the plasma antioxidant activity. In conclusion, diets supplemented with hesperidin and naringin significantly hindered the increase in plasma lipid levels caused by cholesterol feeding. Hesperidin and naringin, bioactive compounds of citrus fruits, are powerful plasma lipid lowering and plasma antioxidant activity increasing flavonones. Copyright © 2007 Society of Chemical Industry     

Inhibitory effects of Hibiscus sabdariffa L extract on low‐density lipoprotein oxidation and anti‐hyperlipidemia in fructose‐fed and cholesterol‐fed rats

Hibiscus sabdariffa L extract (HSE) is an aqueous extract of Hibiscus sabdariffa L flowers that is used as a local soft drink and medical herb in Taiwan. Oxidation of low‐density lipoprotein (LDL) has been shown to increase the incidence of atherosclerosis. In this study, we determined the antioxidative activity of HSE on LDL oxidation by examining relative electrophoretic mobilities (REM) and thiobarbituric acid‐reactive substances (TBARS). The data revealed an inhibitory effect of HSE on Cu²⁺‐mediated REM and TBARS. HSE exhibited a remarkable ability to reduce cholesterol degradation and ApoB fragmentation. Overall, HSE showed a high potency to inhibit the production of oxidized LDL induced by copper and, specifically, to reduce serum triglycerides in high‐fructose diet (HFD) fed rats and serum cholesterol in high‐cholesterol diet (HCD) fed animals. The levels of LDL and the ratio of LDL‐cholesterol (LDL‐C) to HDL‐cholesterol (HDL‐C) were reduced by HSE in both hyperlipidaemia models. Based on these findings, we suggest that HSE may be used to inhibit LDL oxidation and to prevent various types of hyperlipidaemia in HFD‐ or HCD‐fed rats. Copyright © 2004 Society of Chemical Industry     

Stevia rebaudiana Bertoni extract supplementation improves lipid and carnitine profiles in C57BL/6J mice fed a high‐fat diet

BACKGROUND: Stevia (Stevia rebaudiana Bertoni) is a non‐caloric natural‐source alternative to artificially produced sugar substitutes. This study investigated the effect of stevia extract on lipid profiles in C57BL/6J mice. Forty mice were divided into four groups: N‐C (normal diet and distilled water), H‐C (high‐fat diet and distilled water), H‐SC (high fat diet and sucrose, 1 mL kg^?1 per day), and H‐SV (high‐fat diet and stevia extract, 1 mL kg^?1 per day). RESULTS: Body weight gain was significantly higher in the H‐SC group than in the H‐SV group. Triglyceride concentrations in serum and liver were lower in the H‐SV group than in the H‐SC group. Serum total cholesterol concentrations were lower in the H‐SV and H‐C groups compared to the H‐SC group. The concentrations of acid‐insoluble acylcarnitine (AIAC) in serum were higher in the H‐SV group than in the H‐C and H‐SC groups and the acyl/free carnitine level in liver was significantly higher in the H‐SV group than in the N‐C group. These results were supported by mRNA expression of enzymes related to lipid metabolism (ACO, PPARα, ACS, CPT‐I, ACC) assessed by real‐time polymerase chain reaction. CONCLUSION: These results suggest that the supplementation of stevia extract might have an anti‐obesity effect on high‐fat diet induced obese mice. Copyright © 2010 Society of Chemical Industry     

Cholesterol and lipid oxidation in raw and pan‐fried minced beef stored under aerobic packaging

BACKGROUND: The type of packaging atmosphere has been reported as a technological factor that consistently affects the quality of lipid fraction in meat. Oxidation of cholesterol and lipids was evaluated before and after pan frying in commercial refrigerated minced beef stored under aerobic atmosphere for 1 and 8 days. RESULTS: In raw beef, cholesterol and lipid oxidation developed at a slow rate. Cholesterol oxidation products (COPs) did not significantly vary (～8 µg COPs g^?1 of fat) over 8 days, while in the same period thiobarbituric acid reactive substances (TBARS) less than doubled (from 0.7 to 1.2 malondialdehyde equivalents kg^?1 of muscle). Pan frying did not influence the oxidative degree in the fresh product but consistently catalyzed cholesterol oxidation in stored beef. A significant increase was assessed in beef at the end of storage: from 8.6 to 30.0 µg COPs g^?1 of fat in raw and cooked beef, respectively. CONCLUSION: Aerobic packaging did not appear as a pro‐oxidant factor in fresh minced beef with a good oxidative quality during a short period of refrigerated storage. Copyright © 2010 Society of Chemical Industry     

Effect of natural antioxidants on heat‐induced,copper(II)‐catalysed,oxidative degradation of quercetin and rutin (quercetin 3‐O‐rutinoside) in aqueous model systems

The citrate/Cu²⁺‐catalysed degradation of quercetin and rutin (1.0 mM ) was studied in an aqueous model system, pH 8.0, at 97 °C, with respect to the addition of natural, water‐soluble antioxidants, including ascorbic acid (ASA), catechin (CT) and cysteine (CY). Quercetin decomposition was found to be inhibited to a significant extent by the addition of ASA and CY at millimolar ratios of 1:1 and 1:2, but CT gave significantly lower inhibition (P < 0.05) compared with both ASA and CY. In rutin solutions, significant inhibition (P < 0.05) was achieved only with the addition of CT and CY at a millimolar ratio of 1:2. The addition of both ASA and CY to solutions of either flavonol also inhibited browning (A₄₂₀) development, but CT provoked significant increases. © 2002 Society of Chemical Industry