A commercial extract of fruits and vegetables, Oxxynea, acts as a powerful antiatherosclerotic supplement in an animal model by reducing cholesterolemia, oxidative stress, and NADPH oxidase expression

Endogenous antioxidant defense induction by melon superoxide dismutase reduces cardiac hypertrophy in spontaneously hypertensive rats

We assessed the influence of SODB, a melon superoxide dismutase (SOD), on left ventricular (LV) hypertrophy in SHR. SODB (4 or 40U SOD) was given orally for 4 or 28 days to SHR. For each treatment period, LV weight index (LVWI) and cardiomyocytes size were measured. SOD, glutathione peroxidase (GPx) and catalase expressions, and LV production and presence of superoxide anion were determined. Pro-inflammatory markers were also measured. SODB reduced LVWI and cardiomyocytes size after 4 or 28 days. Cardiac SOD and GPx increased by 30-40% with SODB. The presence but not production of superoxide anion was significantly reduced by SODB. No effect of SODB was detected on inflammatory status in any group. The beneficial effect of SODB on cardiac hypertrophy seems to be related to the stimulation of endogenous antioxidant defense, suggesting that SODB may be of interest as a dietary supplementation during conventional antihypertensive therapy.

Cafeteria diet induces obesity and insulin resistance associated with oxidative stress but not with inflammation: improvement by dietary supplementation with a melon superoxide dismutase

Oxidative stress is involved in obesity. However, dietary antioxidants could prevent oxidative stress-induced damage. We have previously shown the preventive effects of a melon superoxide dismutase (SODB) on oxidative stress. However, the mechanism of action of SODB is still unknown. Here, we evaluated the effects of a 1-month curative supplementation with SODB on the liver of obese hamsters. Golden Syrian hamsters received either a standard diet or a cafeteria diet composed of high-fat, high-sugar, and high-salt supermarket products, for 15 weeks. This diet resulted in insulin resistance and in increased oxidative stress in the liver. However, inflammatory markers (IL-6, TNF-α, and NF-κB) were not enhanced and no liver steatosis was detected, although these are usually described in obesity-induced insulin resistance models. After the 1-month supplementation with SODB, body weight and insulin resistance induced by the cafeteria diet were reduced and hepatic oxidative stress was corrected. This could be due to the increased expression of the liver antioxidant defense proteins (manganese and copper/zinc superoxide dismutase, catalase, and glutathione peroxidase). Even though no inflammation was detected in the obese hamsters, inflammatory markers were decreased after SODB supplementation, probably through the reduction of oxidative stress. These findings suggest for the first time that SODB could exert its antioxidant properties by inducing the endogenous antioxidant defense. The mechanisms underlying this induction need to be further investigated.

Curative diet supplementation with a melon superoxide dismutase reduces adipose tissue in obese hamsters by improving insulin sensitivity

SCOPE

Obesity-related metabolic syndrome is often associated with a decrease of insulin sensitivity, inducing several modifications. However, dietary antioxidants could prevent insulin resistance. We have previously shown the preventive effects of a melon superoxide dismutase (SOD) in obese hamsters. However, its antioxidant effects have never been studied on adipose tissue.

METHODS AND RESULTS

We evaluated the effects of a 1-month curative supplementation with SODB on the adipose tissue of obese hamsters. Animals received either a standard diet or a cafeteria diet for 15 wk. Cafeteria diet induced obesity and related disorders, including insulin resistance and oxidative stress, in the abdominal adipose tissue. After SODB supplementation, the adipose tissue weight was decreased, probably by activating adipocytes lipolysis and thus reducing their size. SODB treatment also resulted in abdominal adipose tissue fibrosis reduction. Finally, SODB administration increased the expression of endogenous antioxidant enzymes and thus reduced oxidative stress and insulin resistance. The improvement of insulin sensitivity observed after SODB treatment could explain adipocyte lipolysis activation and fibrosis reduction.

CONCLUSION

These findings demonstrate that a dietary SOD supplementation could be a useful strategy against obesity-related modifications in adipose tissue.

Dietary exposure to silver nanoparticles in Sprague-Dawley rats: effects on oxidative stress and inflammation

Due to undesirable hazardous interactions with biological systems, we evaluated the effect of silver nanoparticles (AgNPs) intake on oxidative stress and inflammation. Rats received for 81 days a standard diet (Controls) or a standard diet plus 500 mg/d/kg BW AgNPs. We assayed plasma lipids, and oxidative stress was assessed by measuring liver and heart superoxide anion production (O₂°⁻) and liver malondialdehyde levels (MDA). Antioxidant status was appraised using plasma paraoxonase activity (PON), plasma antioxidant capacity (PAC) and liver superoxide dismutase activity (SOD). Liver inflammatory cytokines TNFα and IL-6 levels and plasma alanine aminotransferase (ALT) were assayed. Compared with Controls, AgNPs raised cholesterolemia (9.5%), LDL-cholesterol (30%), and lowered triglycerides (41%). They also increased liver (30%) and cardiac (41%) O₂°⁻ production, reduced PON activity (15%) and raised liver TNFα (9%) and IL-6 (∼12%). Plasma ALT activity rose (12%) after treatment with AgNPs. However, PAC and liver MDA and SOD activity were unchanged. These features indicate that exposure to 500 mg/d/kg BW of AgNPs results in liver damage by a dysregulation of lipid metabolism, highlighting liver and heart as the most sensitive organs to the deleterious effects. Our findings also demonstrate for the first time the oxidative and inflammatory effects of dietary AgNPs.

Lipidomic and metabolomic analyses reveal potential plasma biomarkers of early atheromatous plaque formation in hamsters

AIMS

Atherosclerosis is the main pathological process contributing to cardiovascular disease, with diet being the most important factor involved. Although the lipidome of atheromatous plaque has been studied previously, the use of comparative lipidomics and metabolomics in plasma in early atherogenesis could lead to the discovery of plasma biomarkers that allow not only disease prediction but also measurement of disease progression.

METHODS AND RESULTS

High-throughput techniques, such as liquid chromatography/mass spectrometry, allowed us to compare the circulating and aortic lipidome and plasma metabolome in order to look for new molecular targets involved in atherogenesis. To achieve this objective, we chose the hamster (Mesocricetus auratus) as the best small animal model for diet-induced early atherosclerosis, because its lipoprotein metabolism is similar to that of humans. The results revealed the existence of several, previously unreported, changes in lipid and amino-acid metabolism, the peroxisome proliferator-activated receptor γ pathway, and oxidative and endoplasmic reticulum stress, also involving cell senescence. Furthermore, as a proof of concept in the modelling of dietary influences in atherogenesis, we have measured the effect of a potential anti-atherogenic polyphenol extract on the reported pathways. Our results support a previously unknown role for taurocholic acid as a potential plasma biomarker of early atheromatous plaque formation.

CONCLUSION

The use of comparative liquid chromatography/mass spectrometry-based lipidomics and metabolomics allows the discovery of novel pathways in atherogenesis, as well as new potential plasma biomarkers, which could allow us to predict disease in its early stages and measure its progression.

Vineatrol and cardiovascular disease: beneficial effects of a vine-shoot phenolic extract in a hamster atherosclerosis model

We evaluated the effect of the intake of a grapevine-shoot phenolic extract (Vineatrol 30) on early atherosclerosis in hamsters fed a hyperlipidic diet. Golden Syrian hamsters received for 13 weeks either a standard diet, a high-fat (HF) diet, or the HF diet plus Vineatrol 30 at 0.04, 0.2, or 1.0 mg/(kg body weight/d). We measured plasma lipids and glucose, insulin, leptin and adiponectin, as well as liver TNF-α and IL-6 levels. Oxidative stress was assessed by measuring plasma paraoxonase activity (PON) and liver superoxide anion production (O(2)(•-)). The aortic fatty streak area (AFSA) was also determined. In comparison with HF group, we demonstrated that the highest dose of Vineatrol 30 was capable of decreasing AFSA (67%), insulinemia (40%), and leptinemia (8.7%), which were increased by the HF diet. We also showed increased O(2)(•-) production (35%) and a rise in levels of the liver proinflammatory cytokines TNF-α (22%) and IL-6 (21%), accompanied by a fall in PON activity (56%) due to the HF diet versus the standard diet. In contrast, except plasma adiponectin levels that are not changed, Vineatrol 30 treatment lowered AFSA (67%), O(2)(•-) production (36%), insulin resistance (42%), leptinemia (9%), liver TNF-α (18%) and IL-6 (15%), while it rose PON activity (29%). These findings demonstrate the preventive effects of polyphenols present in Vineatrol 30 in managing cardiovascular, metabolic, and inflammatory risk factors.

Raspberry juice consumption, oxidative stress and reduction of atherosclerosis risk factors in hypercholesterolemic golden Syrian hamsters

The effects of raspberries on early atherosclerosis in Syrian hamsters were investigated using three juices prepared from var. Cardinal, Glen Ample and Tulameen berries. The hamsters received an atherogenic diet for 12 weeks and at the same time a juice at a daily dose corresponding to the consumption of 275 ml by a 70 kg human. A control group received the same diet with water instead juice. The principal polyphenolic compounds in the juices were anthocyanins and ellagitannins, which were present at concentrations of 218-305 μg mL(-1) and 45-72 μg mL(-1), respectively. The three juices had similar but not identical effects. They all inhibited cardiac and aortic production of superoxide anion and increased hepatic glutathione peroxidase activity although only Tulameen juice brought about a significant increase in superoxide dismutase activity. Glen Ample was the only juice to significantly increase plasma paraoxonase activity. All the juices lowered plasma triglyceride level while consumption of Tulameen and Cardinal, but not Glen Ample, significantly lowered plasma total cholesterol and LDL-cholesterol. Cardinal was the sole juice to significantly increase HDL-cholesterol and likewise it also significantly reduced body weight. These findings suggest that moderate consumption of raspberry juices can help to prevent the development of early atherosclerosis, with the underlying mechanisms related to improved antioxidant status and serum lipid profiles.

Use of hamster as a model to study diet-induced atherosclerosis

Golden-Syrian hamsters have been used as an animal model to assess diet-induced atherosclerosis since the early 1980s. Advantages appeared to include a low rate of endogenous cholesterol synthesis, receptor-mediated uptake of LDL cholesterol, cholesteryl ester transfer protein activity, hepatic apoB-100 and intestinal apoB-48 secretion, and uptake of the majority of LDL cholesterol via the LDL receptor pathway. Early work suggested hamsters fed high cholesterol and saturated fat diets responded similarly to humans in terms of lipoprotein metabolism and aortic lesion morphology. Recent work has not consistently replicated these findings. Reviewed was the literature related to controlled hamster feeding studies that assessed the effect of strain, background diet (non-purified, semi-purified) and dietary perturbation (cholesterol and/or fat) on plasma lipoprotein profiles and atherosclerotic lesion formation. F1B hamsters fed a non-purified cholesterol/fat-supplemented diet had more atherogenic lipoprotein profiles (nHDL-C > HDL-C) than other hamster strains or hamsters fed cholesterol/fat-supplemented semi-purified diets. However, fat type; saturated (SFA), monounsaturated or n-6 polyunsaturated (PUFA) had less of an effect on plasma lipoprotein concentrations. Cholesterol- and fish oil-supplemented semi-purified diets yielded highly variable results when compared to SFA or n-6 PUFA, which were antithetical to responses observed in humans. Dietary cholesterol and fat resulted in inconsistent effects on aortic lipid accumulation. No hamster strain was reported to consistently develop lesions regardless of background diet, dietary cholesterol or dietary fat type amount. In conclusion, at this time the Golden-Syrian hamster does not appear to be a useful model to determine the mechanism(s) of diet-induced development of atherosclerotic lesions.

When cholesterol is not cholesterol: a note on the enzymatic determination of its concentration in model systems containing vegetable extracts

BACKGROUND

Experimental evidences demonstrate that vegetable derived extracts inhibit cholesterol absorption in the gastrointestinal tract. To further explore the mechanisms behind, we modeled duodenal contents with several vegetable extracts.

RESULTS

By employing a widely used cholesterol quantification method based on a cholesterol oxidase-peroxidase coupled reaction we analyzed the effects on cholesterol partition. Evidenced interferences were analyzed by studying specific and unspecific inhibitors of cholesterol oxidase-peroxidase coupled reaction. Cholesterol was also quantified by LC/MS. We found a significant interference of diverse (cocoa and tea-derived) extracts over this method. The interference was strongly dependent on model matrix: while as in phosphate buffered saline, the development of unspecific fluorescence was inhibitable by catalase (but not by heat denaturation), suggesting vegetable extract derived H(2)O(2) production, in bile-containing model systems, this interference also comprised cholesterol-oxidase inhibition. Several strategies, such as cholesterol standard addition and use of suitable blanks containing vegetable extracts were tested. When those failed, the use of a mass-spectrometry based chromatographic assay allowed quantification of cholesterol in models of duodenal contents in the presence of vegetable extracts.

CONCLUSIONS

We propose that the use of cholesterol-oxidase and/or peroxidase based systems for cholesterol analyses in foodstuffs should be accurately monitored, as important interferences in all the components of the enzymatic chain were evident. The use of adequate controls, standard addition and finally, chromatographic analyses solve these issues.

An SOD rich melon extract Extramel prevents aortic lipids and liver steatosis in diet-induced model of atherosclerosis

BACKGROUND AND AIMS

Oxidative stress has been involved in the early steps of atherosclerosis and previous studies on hypercholesterolemic hamsters have shown that non-enzymatic antioxidant could prevent fatty streak formation. Therefore, we investigated whether a melon juice extract (Extramel((R))) rich in superoxide dismutase (SOD) would prevent the development of early atherosclerosis.

METHODS AND RESULTS

The effects of Extramel((R)) on plasma cholesterol, aortic fatty streak formation, hepatic steatosis, superoxide anion tissue production and NAD(P)H oxidase expression were studied in hamsters fed with an atherogenic diet (HF), receiving by gavage either water or Extramel((R)) at 0.7, 2.8 or 5.6mg/d. After 12 weeks of oral administration, Extramel((R)) lowered plasma cholesterol and non-HDL cholesterol and induced blood and liver SOD activities. It also strongly reduced the area of aortic fatty streak by 49-85%, cardiac (45%) and liver (67%) production of superoxide anion and liver p22(phox) subunit of NAD(P)H oxidase expression by 66%, and attenuated the development of hepatic steatosis.

CONCLUSION

These findings support the view that chronic consumption of melon juice extract rich in SOD has potential beneficial effects with respect to the development of atherosclerosis and liver steatosis, emphasizing its use as potential dietary therapy.

Oxidative stress in rats fed a high-fat high-sucrose diet and preventive effect of polyphenols: Involvement of mitochondrial and NAD(P)H oxidase systems

Mitochondrial and NADPH oxidase systems and oxidative stress were investigated in 12 week high-fat high-sucrose (HFHS) diet-fed rats. A protective effect of wine polyphenol (PP) extract was also examined. In liver, maximal activities of CII and CII+III mitochondrial complexes were decreased but NADPH oxidase expression (p22(phox) and p47(phox)) and NADPH oxidase-dependent superoxide anion production were not modified, whereas oxidative stress (lipid and protein oxidation products and antioxidant systems) was increased with HFHS diet. In muscle, anion superoxide production was slightly increased while mitochondrial complex activities and lipid and protein oxidation products were not modified with HFHS diet. In heart, NADPH oxidase expression and superoxide anion production were increased, and maximal activity of mitochondrial respiratory chain complexes or oxidative stress parameters were not modified. Wine polyphenol extract had an inhibiting effect on liver oxidative stress and on heart NADPH oxidase expression and superoxide anion production, and on induction of hepatic steatosis with HFHS diet. Induction of mitochondrial dysfunction could be a primary event in the development of oxidative stress in liver, while in skeletal muscle and in heart the NADPH oxidase system seems to be mainly involved in oxidative stress. Wine polyphenol extract was shown to partially prevent oxidative stress in liver and heart tissues and to nearly completely prevent steatosis development in liver.

Fungal chitin-glucan from Aspergillus niger efficiently reduces aortic fatty streak accumulation in the high-fat fed hamster, an animal model of nutritionally induced atherosclerosis

The effects of chitin-glucan (CG) on early atherosclerosis, cardiac production of superoxide anion, and hepatic antioxidant enzymes were studied in an animal model of atherosclerosis. Three groups of 12 hamsters were fed an atherogenic diet for 12 weeks. They received by gavage either water (control group) or CG in water at a dose of 21.4 mg/kg BW x d-1 of chitin-glucan (CG ld) or 42.8 mg/kg BW x d-1 (GG hd). CG did not affect plasma cholesterol but lowered triglycerides. It also strongly reduced the area of aortic fatty streak deposition by 87-97%, cardiac production of superoxide anion by 25% and liver MDA by 77-85%, and enhanced liver superoxide dismutase activity by 7-45% and glutathionne peroxidase activity by 38-120%. These findings support the view that chronic consumption of chitin-glucan has potential beneficial effects with respect to the development of atherosclerosis. The underlying mechanism is related mainly to improving the antioxidant status.