Etude de la disponibilité biologique du sélénium (application à la valorisation nutritionnelle d'une cyanobactérie enrichie)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Effets d'un concentré de melon, particulièrement riche en superoxyde dismutase, sur un modèle d'obésité nutritionnellement induite (hypothèses de mécanismes d'action)

Les effets d'un concentré de melon, SODB®, particulièrement riche en SOD, ont été étudiés en mode curatif sur un modèle animal d'obésité nutritionnellement induite. La question du mécanisme d'action de ce concentré de melon a également été posée dans ce travail.Dans la première partie, des tests in vitro ont permis d'évaluer et de mieux caractériser le pouvoir antioxydant de SODB®. Il a également été montré, grâce à une étude sur rats sains, que SODB® n'était pas toxique aux doses utilisées.Dans une deuxième partie, des effets bénéfiques de SODB® sur le foie et le tissu adipeux d'animaux obèses ont été démontrés.Dans une dernière partie, le mécanisme d'action de SODB® a été discuté. Pour cela, les différents résultats obtenus sur SODB® ont été comparés avec les données d'une revue sur les effets de l'administration de SODs. Grâce à ce travail, des hypothèses de mécanisme d'action ont pu être proposées. En effet, SODB® semblerait agir en augmentant l'expression des enzymes antioxydantes endogènes. L'induction de la défense antioxydante pourrait passer par l'activation de la voie du Nrf2/ARE, à la suite d'une cascade d'évènements initiée au niveau de la barrière intestinale. La compréhension totale du mécanisme d'action de ce concentré de melon nécessite cependant plus d'investigations.The effects of a curative supplementation of a melon concentrate, SODB®, particularly rich in SOD, have been studied on a diet-induced obesity animal model. In this work, we also wondered what mechanisms of action are involved in SODB® efficacy.First, we evaluated and characterized the antioxidant capacity of SODB® with in vitro tests. The safety of several doses used for SODB® supplementation has also been demonstrated on healthy rats.Then, we showed beneficial effects of SODB® on the liver and the adipose tissue of obese animals.Finally, we discussed the mechanism of action of SODB®, comparing all results obtained after SODB® supplementation with a review on SODs administration effects.This work allowed to propose hypothesis of mechanism of action. Indeed, SODB® seems to exert its antioxidant properties inducing increased endogenous antioxidant enzymes expression. The Nrf2/ARE pathway could be involved in this induction, after cascade events from intestinal barrier. More investigations are needed to determine the complete mechanism of action of this melon concentrate.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Les antioxydants d'un extrait de jus de melon, l'Extramel (potentialités dans la prévention de pathologies liées au stress oxydant sur le modèle hamster doré syrien)

On étudie les potentialités d'action d'un concentré de jus de melon riche en antioxydants, Extramel®, sur modèles pathologiques de stress oxydant, d'athérosclérose et d'obésité, d'origine nutritionnelle. La première partie étudie la faisabilité de l'étude en testant la capacité d'Extramel® à prévenir le stress oxydant in vitro sur modèle cellulaire THP-1. Nous y avons mis en évidence l'action inhibitrice d'Extramel® sur la production de l'anion superoxyde en diminuant l'expression de la sous-unité p22phox de la NADPH oxydase. Ceci nous a conduit à aborder l'étude in vivo, sur modèle animal d'athérosclérose. Après 12 semaines d'expérimentation, Extramel® prévient le stress oxydant, diminue la dyslipidémie ainsi que les dépôts lipidiques aortiques. Dans une troisième partie, Extramel® a été apporté à des hamsters recevant un régime induisant l'obésité. Nous montrons une prévention de l'obésité et de la stéatose hépatique associée, en rétablissant la balance leptine/adiponectine, en réduisant l'insulinémie et l'insulino-résistance. Plusieurs hypothèses sur le(s) mécanisme(s) d'action de l'extrait sont proposées; la plus plausible serait l'action antioxydante intra-luminale de ses enzymes, protégeant ainsi l'organisme de l'absorption de lipides radicalaires et/ou d'antioxydants non enzymatiques inactivés. L'éventualité qu'un peptide bioactif issu de l'hydrolyse intestinale de la SOD reste une hypothèse à ne pas rejeter. En résumé, ce travail met en avant les potentialités d'Extramel® en tant que complément alimentaireThe purpose of this study is to explore the action potential of a concentrated melon juice particularly rich in antioxidants, Extramel®, on pathological models of oxidative stress, early atherosclerosis and obesity from nutritional origin. In the first part of this work, we explored the feasibility of this study, testing the ability of the extract to prevent oxidative stress in vitro on cell model THP-1. This enabled us to demonstrate the inhibitory action of Extramel® on the production of superoxide anion by reducing the expression of p22phox subunit of the NADPH oxidase. These results led us to address in vivo studies on animal model of atherosclerosis. After a 12-week experimental period, Extramel® prevents oxidative stress, reduces dyslipidemia and aortic lipid deposition. In a third part, Extramel® was given to hamsters fed a diet inducing obesity. We show the prevention of obesity and of fatty liver associated, including restoring the balance leptin / adiponectin, reducing insulin and insulin resistance induced by this diet. Several assumptions about the mechanism(s) of action of the antioxidants from the extract are proposed. The most plausible concerns the intra-luminal action of antioxidant these enzymes, thus protecting the body against the absorption of fat radicals and / or non-enzymatic antioxidants inactivated. The possibility that a bioactive peptide issuing from the intestinal hydrolysis of SOD remains a hypothesis that cannot be ruled out. In summary, this work highlights the potential of Extramel® as a dietary supplementMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Recherche de mécanismes d'action des polyphénols du vin et des produits de la vigne, dans la prévention des maladies cardiovasculaires (Caractérisation de métabolites actifs de ces composés)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Dietary supplementation with a specific melon concentrate reverses vascular dysfunction induced by cafeteria diet

Background: Obesity-related metabolic syndrome is associated with high incidence of cardiovascular diseases partially consecutive to vascular dysfunction. Therapeutic strategies consisting of multidisciplinary interventions include nutritional approaches. Benefits of supplementation with a specific melon concentrate, enriched in superoxide dismutase (SOD), have previously been shown on the development of insulin resistance and inflammation in a nutritional hamster model of obesity. Objective: We further investigated arterial function in this animal model of metabolic syndrome and studied the effect of melon concentrate supplementation on arterial contractile activity. Design and results: The study was performed on a hamster model of diet-induced obesity. After a 15-week period of cafeteria diet, animals were supplemented during 4 weeks with a specific melon concentrate (Cucumis melo L.) Contractile responses of isolated aorta to various agonists and antagonists were studied ex vivo. Cafeteria diet induced vascular contractile dysfunction associated with morphological remodeling. Melon concentrate supplementation partially corrected these dysfunctions; reduced morphological alterations; and improved contractile function, especially by increasing nitric oxide bioavailability and expression of endogenous SOD. Conclusions: Supplementation with the specific melon concentrate improves vascular dysfunction associated with obesity. This beneficial effect may be accounted for by induction of endogenous antioxidant defense. Such an approach in line with nutritional interventions could be a useful strategy to manage metabolic syndrome–induced cardiovascular trouble

La supplémentation alimentaire avec un concentré spécifique de melon corrige la dysfonction vasculaire induite par un régime cafétéria

International audienceBackground: Obesity-related metabolic syndrome is associated with high incidence of cardiovascular diseases partially consecutive to vascular dysfunction. Therapeutic strategies consisting of multidisciplinary interventions include nutritional approaches. Benefits of supplementation with a specific melon concentrate, enriched in superoxide dismutase (SOD), have previously been shown on the development of insulin resistance and inflammation in a nutritional hamster model of obesity. Objective: We further investigated arterial function in this animal model of metabolic syndrome and studied the effect of melon concentrate supplementation on arterial contractile activity. Design and results: The study was performed on a hamster model of diet-induced obesity. After a 15-week period of cafeteria diet, animals were supplemented during 4 weeks with a specific melon concentrate (Cucumis melo L.) Contractile responses of isolated aorta to various agonists and antagonists were studied ex vivo. Cafeteria diet induced vascular contractile dysfunction associated with morphological remodeling. Melon concentrate supplementation partially corrected these dysfunctions; reduced morphological alterations ; and improved contractile function, especially by increasing nitric oxide bioavailability and expression of endogenous SOD. Conclusions: Supplementation with the specific melon concentrate improves vascular dysfunction associated with obesity. This beneficial effect may be accounted for by induction of endogenous antioxidant defense. Such an approach in line with nutritional interventions could be a useful strategy to manage metabolic syndromeÁinduced cardiovascular trouble

Short-term assessment of toxicological aspects, oxidative and inflammatory response to dietary melon superoxide dismutase in rats

The protective effects of SODB, a gastro-resistant encapsulated melon superoxide dismutase, on haematological and biochemical parameters and inflammatory and oxidative status, were evaluated in the blood and liver tissue. The study consisted in a 28-day experiment on rats supplemented with three doses (10, 40 and 160 U SOD/day) of SODB-M, SODB-D or SODB-S, different depending on the nature of the coating (palm oil, shellac or gum Arabic respectively). No mortality, abnormal clinical signs, behavioural changes or macroscopic findings were observed whatever the groups. Haematological parameters (total red blood cell count, haemoglobin content, haematocrit, red cell indices, white blood cell count and platelets count) were not modified in SODB treated-groups. No marked change was recorded in biochemical parameters (plasma urea, creatinine, lipids, electrolytes, bilirubin, transaminases and gamma-glutamyl transferase). The liver endogenous antioxidant enzymes (copper/zinc and manganese superoxide dismutase) expressions were significantly increased in the rats receiving the highest dose of SODB (160 U SOD/day) whatever the coating. Moreover, interleukin-6, a marker of inflammation, was significantly decreased in these high dose-treated-groups

Antioxidant capacity and angiotensin I converting enzyme inhibitory activity of a melon concentrate rich in superoxide dismutase

International audienceAntioxidant capacity and angiotensin 1-converting enzyme (ACE) inhibitory activity of a melon concentrate rich in superoxide dismutase (SOD-MC) were investigated in vitro. The total antioxidant capacity (TAC) was measured by the Trolox equivalent antioxidant capacity assay (TEAC), the 1,1-dipheny1-2-picrylhydrazyl (DPPH) radical assay, and the ferric reducing antioxidant power assay (FRAP). The ability of the extract to scavenge three specific reactive oxygen species (superoxide radical anion (O-2(center dot-)), hydroxyl radical (HO center dot) and hydrogen peroxide (H2O2)) was also investigated in order to better evaluate its antioxidant properties. Even if the measures of TAC were relatively low, results clearly established an antioxidant potential of SOD-MC that exhibited the highest radical-scavenging activity towards O-2(center dot-), with a IC50 12-fold lower than that of H2O2 or HO center dot. This lets hypothesis that the antioxidant potential of SOD-MC could be mainly due to its high level of SOD. Moreover, for the first time, an ACE inhibitory activity of SOD-MC (IC50 = 2.4 +/- 0.1 mg/mL) was demonstrated, showing that its use as a functional food ingredient with potential preventive benefits in the context of hypertension may have important public health implications and should be carefully considered