Activity of Pterostilbene Metabolites against Liver Steatosis in Cultured Hepatocytes

Pterostilbene is a dimethyl ether derivative of resveratrol, less metabolized than its analogue, due to the substitution of two hydroxyl groups with methoxyl groups. Nevertheless, the amounts of pterostilbene phase II metabolites found in plasma and tissues are higher than those of the parent compound. The first aim of this study was to assess whether pterostilbene-4′-O-glucuronide (PT-G) and pterostilbene-4′-O-sulfate (PT-S) were able to prevent triglyceride accumulation in AML12 (alpha mouse liver 12) hepatocytes. This being the case, we aimed to analyze the mechanisms involved in their effects. For this purpose, an in vitro model mimicking the hepatocyte situation in fatty liver was developed by incubating mouse AML12 hepatocytes with palmitic acid (PA). For cell treatments, hepatocytes were incubated with 1, 10 or 25 µM of pterostilbene, pterostilbene-4′-O-glucuronide or pterostilbene-4′-O-sulfate for 18 h. Triglycerides and cell viability were assessed by a commercial kit and crystal violet assay, respectively. Protein expression of enzymes and transporters involved in triglyceride metabolism was analyzed by immunoblot. The results showed for the first time the anti-steatotic effect of pterostilbene metabolites and thus, that they contribute to the preventive effect induced by pterostilbene on steatosis in in vivo models. This anti-steatotic effect is mainly due to the inhibition of de novo lipogenesis.This research was funded by Ministerio de Economía y Competitividad-Fondo Europeo de Desarrollo Regional (grant number AGL-2015-65719-R MINECO/FEDER, UE), Instituto de Salud Carlos III CIBERobn (grant number CB12/03/30007) and University of the Basque Country (grant number GIU 18/173)

Obesitatea eta hari lotutako gaixotasunen dietoterapia

109 p.Obesitatea gaixotasun metaboliko kronikoa da, zeinaren prebalentzia etengabe handitu baita azken hamarkadetan, xxi. mendeko epidemia izena emateraino. Gaixotasun horren ezaugarri nagusietako bat da harekin lotzen diren bestelako osasun-arazoak sortzeko arriskua handitzen duela. Hori dela eta, obesitatearen eta harekin lotzen diren osasun-arazoen tratamendu dietetikoa ondo ezagutzea ezinbestekoa da Giza Nutrizioa eta Dietetika Graduko ikasleentzat. Horiek horrela, eskuliburu honek, Giza Nutrizioko eta Dietetikako Graduko 4. mailan ematen den Dietoterapia ikasgaiaren gaitegiko zenbait patologia bildu eta garatzen ditu. Zehazki, obesitatearen eta patologia horri maiz lotutako osasun-asalduren (gibel-esteatosia, intsulinarekiko erresistentzia eta 2 motako diabetesa, eta dislipemiak eta aterosklerosia) dietoterapia bildu da, horiek izaten direlako kontsulta dietetiko gehienen arrazoiak. Kontuan izanik Dietoterapia ikasgaiak etorkizuneko dietista-nutrizionisten prestakuntzan duen garrantzia, eskuliburu honen helburua da ikasleari eguneratutako euskarri teorikoa ematea (idatzizko testu formatuan)

Current Knowledge on Beetroot Bioactive Compounds: Role of Nitrate and Betalains in Health and Disease

An increase in the prevalence of noncommunicable chronic diseases has been occurring in recent decades. Among the deaths resulting from these conditions, cardiovascular diseases (CVD) stand out as the main contributors. In this regard, dietary patterns featuring a high content of vegetables and fruits, such as the Mediterranean and the DASH diets, are considered beneficial, and thus have been extensively studied. This has resulted in growing interest in vegetable-derived ingredients and food-supplements that may have potential therapeutic properties. Among these supplements, beetroot juice, which is obtained from the root vegetable Beta vulgaris, has gained much attention. Although a significant part of the interest in beetroot juice is due to its nitrate (NO3−) content, which has demonstrated bioactivity in the cardiovascular system, other ingredients with potential beneficial properties such as polyphenols, pigments and organic acids are also present. In this context, the aim of this review article is to analyze the current knowledge regarding the benefits related to the consumption of beetroot and derived food-supplements. Therefore, this article focuses on nitrate and betalains, which are considered to be the major bioactive compounds present in beetroot, and thus in the derived dietary supplements.This research was funded by The Basque Government under Grant PA20/04, the University of the Basque Country under Grant GIU18-173 and CIBEROBN under Grant CB12/03/30007

Risks Associated with the Use of Garcinia as a Nutritional Complement to Lose Weight

Nowadays, obesity is one of the great nutritional problems facing public health. The prevalence of this pathology has increased in a worrying way over recent years, currently reaching epidemic proportions. In this context, nutritional supplements are presented as a therapeutic alternative to which more and more people are turning to. Nutritional supplements to lose weight based on the Garcinia plant, specifically on Garcinia cambogia, are commonly used. The active principle of this plant to which these properties have been attributed, is hydroxycitric acid (HCA). The aim of the present review is to gather reported data concerning the effectiveness of nutritional supplements based on Garcinia extracts on weight loss and their possible negative effects. Contradictory results have been observed regarding the effectiveness of the supplements. While statistically significant weight loss was observed in some studies, no changes were found in others. Regarding safety, although Garcinia supplements have been revealed as safe in the vast majority of the studies carried out in animal models and humans, some cases of hepatotoxicity, serotonin toxicity and mania have been reported. In conclusion, the results suggest that Garcinia-based supplements could be effective in short-term weight loss, although the data are not conclusive. In addition, the safety of the complement should be further studied.This study was funded by Instituto de Salud Carlos III (CIBERobn) under Grant CB12/03/30007 and University of the Basque Country under Grant GIU18-173

Resveratrol Metabolites Are Able to Reduce Steatosis in Cultured Hepatocytes

Steatosis is characterized primarily by excessive lipid accumulation in the form of triglycerides in the liver. Although resveratrol shows a low bioavailability, it has significant positive effects on steatosis. The aim of this study was to analyze whether some phase II and microbial resveratrol metabolites (trans-resveratrol-4′-O-glucuronide (R-4G); trans-resveratrol-3-O-glucuronide (R-3G); trans-resveratrol-3-O-sulfate (R-S) and dihydro-resveratrol (DH-R) were effective in reducing hepatocyte fat accumulation. An in vitro model mimicking the hepatocyte situation in fatty liver was developed by incubating mouse AML12 hepatocytes with palmitic acid (PA). For cell treatments, hepatocytes were incubated with 1, 10, or 25 µM resveratrol or its metabolites. Triglycerides and cell viability were assessed using commercial kits. Protein expression of enzymes and transporters involved in triglyceride metabolism were analyzed by western blot. We show for the first time that resveratrol and all the tested metabolites, at 1 µM, partially prevented lipid accumulation induced by the saturated fatty acid PA in AML12 hepatocytes. This effect was mainly due to the inhibition of de novo lipogenesis. This demonstrates that the low bioavailability of resveratrol is not as big a problem as it was thought to be, because resveratrol metabolites contribute to the delipidating effects of the parent compound.This research was funded by Ministerio de Economía y Competitividad-Fondo Europeo de Desarrollo Regional, grant number AGL-2015-65719-R; Instituto de Salud Carlos III CIBERobn, grant number CB12/03/30007; University of the Basque Country, grant number GIU 18/173

Effect of Microalgae and Macroalgae Extracts on Non-Alcoholic Fatty Liver Disease

The present review aims to gather scientific evidence regarding the beneficial effects of microalgae and macroalgae extracts on non-alcoholic fatty liver disease (NAFLD). The described data show that both microalgae and macroalgae improved this alteration. The majority of the reported studies analysed the preventive effects because algae were administered to animals concurrent with the diet that induced NAFLD. The positive effects were demonstrated using a wide range of doses, from 7.5 to 300 mg/kg body weight/day or from 1 to 10% in the diet, and experimental periods ranged from 3 to 16 weeks. Two important limitations on the scientific knowledge available to date are that very few studies have researched the mechanisms of action underlying the preventive effects of microalgae on NAFLD and that, for the majority of the algae studied, a single paper has been reported. For these reasons, it is not possible to establish the best conditions in order to know the beneficial effects that these algae could bring. In this scenario, further studies are needed. Moreover, the beneficial effects of algae observed in rodent need to be confirmed in humans before we can start considering these products as new tools in the fight against fatty liver disease.This study was funded by University of the Basque Country (grant: GIU18-173) and Carlos III Research Institute (CIBERobn) (grant CB12/03/30007)

Usefulness of Probiotics in the Management of NAFLD: Evidence and Involved Mechanisms of Action from Preclinical and Human Models

The present review aims at analyzing the current evidence regarding probiotic administration for non-alcoholic fatty liver disease (NAFLD) management. Additionally, the involved mechanisms of action modulated by probiotic administration, as well as the eventual limitations of this therapeutic approach and potential alternatives, are discussed. Preclinical studies have demonstrated that the administration of single-strain probiotics and probiotic mixtures effectively prevents diet-induced NAFLD. In both cases, the magnitude of the described effects, as well as the involved mechanisms of action, are comparable, including reduced liver lipid accumulation (due to lipogenesis downregulation and fatty acid oxidation upregulation), recovery of gut microbiota composition and enhanced intestinal integrity. Similar results have also been reported in clinical trials, where the administration of probiotics proved to be effective in the treatment of NAFLD in patients featuring this liver condition. In this case, information regarding the mechanisms of action underlying probiotics-mediated hepatoprotective effects is scarcer (mainly due to the difficulty of liver sample collection). Since probiotics administration represents an increased risk of infection in vulnerable subjects, much attention has been paid to parabiotics and postbiotics, which seem to be effective in the management of several metabolic diseases, and thus represent a suitable alternative to probiotic usage.This research was funded by CIBEROBN under Grant CB12/03/30007 and the Community of Madrid under Grant Y2020/BIO-6600

Effects of Resveratrol Administration in Liver Injury Prevention as Induced by an Obesogenic Diet: Role of Ruminococcaceae

Gut microbiota dysbiosis has been described in several metabolic disruptions, such as non-alcoholic fatty liver disease (NAFLD). Administration of resveratrol has been claimed to elicit benefits against NAFLD along with modulating gut microbiota composition. This investigation aims to study the putative mediating role of gut microbiota in the potential hepato-protective effects of resveratrol in a diet-induced NAFLD rat model. The involvement of bacteria from the Ruminococcaceae family in such effects was also addressed. Resveratrol administration resulted in lowered liver weight and serum total and non-HDL cholesterol concentrations, as well as in increased serum HDL cholesterol levels. The administration of this polyphenol also prevented obesogenic diet-induced serum transaminase increases. In addition, histopathological analysis revealed that resveratrol administration ameliorated the dietary-induced liver steatosis and hepatic inflammation. Gut microbiota sequencing showed an inverse relationship between some bacteria from the Ruminococcaceae family and the screened hepatic markers, whereas in other cases the opposite relationship was also found. Interestingly, an interaction was found between UBA-1819 abundance and resveratrol induced liver weight decrease, suggesting that for this marker resveratrol induced effects were greater when the abundance of this bacteria was high, while no actions were found when UBA-1819 abundance was low.This research was funded by Ministerio de Economía y Competitividad-Fondo Europeo de Desarrollo Regional (grant number AGL-2015-65719-R MINECO/FEDER, UE), Instituto de Salud Carlos III CIBERobn (grant number CB12/03/30007); University of the Basque Country (grant number GIU 18/173) and Synergic R&D Projects in New and Emerging Scientific Areas on the Frontier of Science and Interdisciplinary Nature of The Community of Madrid (METAINFLAMATION-Y2020/BIO-6600)

Resveratrol and Pterostilbene, Two Analogue Phenolic Compounds, Affect Aquaglyceroporin Expression in a Different Manner in Adipose Tissue

Aquaglyceroporins (AQPs) are transmembrane channels that mediate glycerol release and glycerol uptake. They are involved in fat metabolism, with implications in obesity. The aim was to determine whether the administration of resveratrol and pterostilbene during the six weeks of the experimental period would modify AQPs expression in white and brown adipose tissues from Wistar rats fed an obesogenic diet, and to establish a potential relationship with the delipidating properties of these compounds. Consequently, thirty-six rats were divided into four groups: (a) group fed a standard diet; and three more groups fed a high-fat high-sucrose diet: (b) high-fat high-sucrose group: (c) pterostilbene-treated group (30 mg/kg/d): (d) resveratrol-treated group (30 mg/kg/d). Epididymal, subcutaneous white adipose tissues and interscapular brown adipose tissue were dissected. AQPs gene expression (RT-PCR) and protein expression (western-blot) were measured. In white adipose tissue, pterostilbene reduced subcutaneous adipose tissue weight and prevented the decrease in AQP9 induced by obesogenic feeding, and thus glycerol uptake for triglyceride accumulation. Resveratrol reduced epididymal adipose tissue weight and avoided the decrease in AQPs related to glycerol release induced by high-fat high-sucrose feeding, suggesting the involvement of lipolysis in its body-fat lowering effect. Regarding brown adipose tissue, AQP7 seemed not to be involved in the previously reported thermogenic activity of both phenolic compounds.This research has been supported by MINECO (AGL-2015-65719), Instituto de Salud Carlos III (CIBERobn) and Basque Government (IT-572-13; PA18/03)

Influence of different dietary fats on triacylglycerol deposition in rat adipose tissue

It has been demonstrated that triacylglycerol (TAG) mobilization from adipose tissue is selective and depends on fatty acid (FA) chain length, unsaturation and positional isomerism. The present study was performed to determine the influence of dietary fat on the composition of TAG stored in rat perirenal and subcutaneous adipose tissues. These results may provide information on the susceptibility of stored TAG to hydrolysis and further mobilization, and may help to establish an interrelationship between dietary composition and the FA efflux from adipose tissue. TAG molecular species and FA composition were determined by HPLC and GLC respectively. No significant differences were found in either FA or TAG composition between perirenal and subcutaneous adipose depots. The major FA in the dietary fats were present in the adipose tissues of the animals; in most cases, in similar proportions. However, differences were found between dietary and adipose tissue content of minor FA, which suggests that dietary FA composition is altered between ingestion and deposition in adipose tissue. The TAG molecular species of rat adipose tissue were enriched with the FA characteristic of each dietary fat. Dietary sunflower oil was responsible for enrichment with the most polar TAG. This finding may suggest easier mobilization of stored TAG. In conclusion, the process of fatty acid and TAG deposition in rat adipose tissue is selective, and depends on the composition of the diet.Supported by grants (OLI96-2126 and ALI99-0863) from the Comisión Interministerial de Ciencia y Tecnología (CICYT) and the Government of the País Vasco (PI 96/22) and by a felIowship from this Government