Effects of long-term feeding of the polyphenols resveratrol and kaempferol in obese mice

Mitophagy-promoting agents and their ability to promote healthy-aging

The removal of damaged mitochondrial components through a process called mitochondrial autophagy (mitophagy) is essential for the proper function of the mitochondrial network. Hence, mitophagy is vital for the health of all aerobic animals, including humans. Unfortunately, mitophagy declines with age. Many age-associated diseases, including Alzheimer's and Parkinson's, are characterized by the accumulation of damaged mitochondria and oxidative damage. Therefore, activating the mitophagy process with small molecules is an emerging strategy for treating multiple aging diseases. Recent studies have identified natural and synthetic compounds that promote mitophagy and lifespan. This article aims to summarize the existing knowledge about these substances. For readers' convenience, the knowledge is presented in a table that indicates the chemical data of each substance and its effect on lifespan. The impact on healthspan and the molecular mechanism is reported if known. The article explores the potential of utilizing a combination of mitophagy-inducing drugs within a therapeutic framework and addresses the associated challenges of this strategy. Finally, we discuss the process that balances mitophagy, i.e. mitochondrial biogenesis. In this process, new mitochondrial components are generated to replace the ones cleared by mitophagy. Furthermore, some mitophagy-inducing substances activate biogenesis (e.g. resveratrol and metformin). Finally, we discuss the possibility of combining mitophagy and biogenesis enhancers for future treatment. In conclusion, this article provides an up-to-date source of information about natural and synthetic substances that activate mitophagy and, hopefully, stimulates new hypotheses and studies that promote healthy human aging worldwide.

Dietary flavonoid kaempferol reduces obesity-associated hypothalamic microglia activation and promotes body weight loss in mice with obesity

BACKGROUND

Obesity results from an unbalance in the ingested and burned calories. Energy balance (EB) is critically regulated by the hypothalamic arcuate nucleus (ARC) by promoting appetite or anorectic actions. Hypothalamic inflammation, driven by high activation of the microglia, has been reported as a key mechanism involved in the development of diet-induced obesity. Kaempferol (KF), a flavonoid-type polyphenol present in a large number of fruits and vegetables, was shown to regulate both energy metabolism and inflammation.

OBJECTIVES

In this work, we studied the effects of both the central and peripheral treatment with KF on hypothalamic inflammation and EB regulation in mice with obesity.

METHODS

Obese adult mice were chronically (40 days) treated with KF (0.5 mg/kg/day, intraperitoneally). During the treatment, body weight, food intake (FI), feed efficiency (FE), glucose tolerance, and insulin sensitivity were determined. Analysis of microglia activation in the ARC of the hypothalamus at the end of the treatment was also performed. Body weight, FI, and FE changes were also evaluated in response to 5µg KF, centrally administrated.

RESULTS

Chronic administration of KF decreased ∼43% of the density, and ∼30% of the ratio, of activated microglia in the arcuate nucleus. These changes were accompanied by body weight loss, decreased FE, reduced fasting blood glucose, and a tendency to improve insulin sensitivity. Finally, acute central administration of KF reproduced the effects on EB triggered by peripheral administration.

CONCLUSION

These findings suggest that KF might fight obesity by regulating central processes related to EB regulation and hypothalamic inflammation.

Antileishmanial Activity of Lignans, Neolignans, and Other Plant Phenols

Secondary metabolites (SM) from organisms have served medicinal chemists over the past two centuries as an almost inexhaustible pool of new drugs, drug-like skeletons, and chemical probes that have been used in the "hunt" for new biologically active molecules with a "beneficial effect on human mind and body." Several secondary metabolites, or their derivatives, have been found to be the answer in the quest to search for new approaches to treat or even eradicate many types of diseases that oppress humanity. A special place among SM is occupied by lignans and neolignans. These phenolic compounds are generated biosynthetically via radical coupling of two phenylpropanoid monomers, and are known for their multitarget activity and low toxicity. The disadvantage of the relatively low specificity of phenylpropanoid-based SM turns into an advantage when structural modifications of these skeletons are made. Indeed, phenylpropanoid-based SM previously have proven to offer great potential as a starting point in drug development. Compounds such as Warfarin^® (a coumarin-based anticoagulant) as well as etoposide and teniposide (podophyllotoxin-based anticancer drugs) are just a few examples. At the beginning of the third decade of the twenty-first century, the call for the treatment of more than a dozen rare or previously "neglected" diseases remains for various reasons unanswered. Leishmaniasis, a neglected disease that desperately needs new ways of treatment, is just one of these. This disease is caused by more than 20 leishmanial parasites that are pathogenic to humans and are spread by as many as 800 sandfly species across subtropical areas of the world. With continuing climate changes, the presence of Leishmania parasites and therefore leishmaniasis, the disease caused by these parasites, is spreading from previous locations to new areas. Thus, leishmaniasis is affecting each year a larger proportion of the world's population. The choice of appropriate leishmaniasis treatment depends on the severity of the disease and its form of manifestation. The success of current drug therapy is often limited, due in most cases to requiring long hospitalization periods (weeks to months) and the toxicity (side effects) of administered drugs, in addition to the increasing resistance of the parasites to treatment. It is thus important to develop new drugs and treatments that are less toxic, can overcome drug resistance, and require shorter periods of treatment. These aspects are especially important for the populations of developing countries. It was reported that several phenylpropanoid-based secondary metabolites manifest interesting antileishmanial activities and are used by various indigenous people to treat leishmaniasis. In this chapter, the authors shed some light on the various biological activities of phenylpropanoid natural products, with the main focus being on their possible applications in the context of antileishmanial treatment.

Partitioning of fatty acids into tissues and fluids from reproductive organs of ewes as affected by dietary phenolic extracts

Evaluation of dietary interventions with regard to fertility problems often observed in ruminant livestock is of global interest. Though the effects of polyphenol supplementation in ruminants on digestion and food quality are well described, the impact on reproductive tissues and fluids remains scarcely investigated. These compounds protect dietary unsaturated fatty acids (FA) from oxidation and biohydrogenation and thus saturation. In addition, modification of the expression of genes associated with FA metabolism may occur. Therefore, we characterized for the first time the FA profiles of reproductive tissues and fluids and investigated their potential modification by dietary polyphenols in 22 cyclic ewes. The animals were randomly divided into four groups and fed a basal diet of meadow hay and one of four concentrate types either non-supplemented (control) or supplemented with grape seed extract, Acacia mearnsii bark extract (13 g/kg dry matter (DM) each) or a combination of both (26 g/kg DM). After 10 weeks of feeding, the animals were slaughtered. Samples of reproductive (oviduct, uterus) and metabolically differently active tissues (liver, muscle, adipose) as well as of plasma and fluids from oviduct and uterus were analysed for their FA composition. In addition, the expression of lipid metabolic and antioxidant genes was analysed in all tissues except the adipose tissue. Fatty acid profiles in tissues and fluids as well as gene expression in tissues significantly differed between the different fluids and tissues. In contrast, only a few diet and matrix (fluid or tissue) × diet interactions were observed. Still, the FA profile of the uterus was the only one not at all affected by the diet. The mRNA expression was not affected by the diet for most of the genes investigated, which might in part be explained by the similar plasma polyphenol concentrations found at slaughter. Overall, our findings contribute to an improved understanding of the characteristic FA composition of reproductive tissues and fluids in sheep. In addition, the effect of polyphenols on different tissues, fluids and tissue gene expression has been confirmed as described in other animal species.

The influence of dietary conditions in the effects of resveratrol on hepatic steatosis

Non-alcoholic fatty liver disease (NAFLD) is considered the major cause for the development of chronic liver alterations.

Resveratrol supplementation improves metabolic control in rats with induced hyperlipidemia and type 2 diabetes

Resveratrol was recognized as the major factor responsible for the beneficial properties of red wine. Several resveratrol-based dietary supplements are available, but their efficacy has not been sufficiently tested. This study was designed to examine the effect of resveratrol supplementation, using a commercially available product, on the metabolic status of experimental animals with induced hyperlipidemia or type 2 diabetes mellitus (T2DM). Hyperlipidemia was induced by feeding the rats a standard pellet diet supplemented with cholesterol. T2DM was induced by adding 10% fructose to drinking water and streptozotocin. Treatment with resveratrol-based supplement improved glycemic control in diabetic animals and significantly decreased serum low-density-lipoprotein (LDL) and triglyceride levels, concurrently increasing the high-density-lipoprotein (HDL) levels in animals with hyperlipidemia. Resveratrol-treated animals had improved tolerance to glucose loading. Supplementation did not induce alterations in parameters of liver and renal function. Findings indicate that commercial resveratrol supplement improves metabolic control in rats with induced hyperlipidemia and T2DM.

Effect of Kaempferol Pretreatment on Myocardial Injury in Rats

The present study was undertaken to evaluate the effect of kaempferol in isoprenaline (ISP)-induced myocardial injury in rats. ISP was administered subcutaneously for two subsequent days to induce myocardial injury. Assessment of myocardial injury was done by estimation of hemodynamic functions, myocardial infarcted area, cardiac injury markers, lipid profile, oxidative stress, pro-inflammatory cytokines and histopathology of heart and liver. Rats pretreated with kaempferol showed reduction in the myocardial infarcted area and heart rate. However, no improvement was observed in change in body weight, mean arterial, systolic and diastolic blood pressure. Kaempferol showed significant decrease in serum LDH, CK-MB, troponin-I and lipid profile. However, highest dose of kaempferol did not reduce the serum triglyceride level. Further, antioxidant enzymes, SOD and catalase, were also higher. However, reduced glutathione, serum SGOT and creatinine did not show any improvement. Kaempferol showed reduction in MDA level. Kaempferol at highest dose showed reduction in pro-MMP-2 expression and MMP-9 level. mRNA expression level of TNF-α was not different in kaempferol-pretreated myocardial injured rats with ISP-alone group. Pretreatment with kaempferol at highest dose showed mild mononuclear infiltration and degenerative changes in heart tissue section of myocardial injured rats. Rats pretreated with kaempferol at higher concentration showed normal cordlike arrangement of hepatocytes with moderate swelling of hepatocytes (vacuolar degeneration) around the central vein. Study suggests that kaempferol attenuated lipid profile, infarcted area and oxidative stress in ISP-induced myocardial injury in rats.

Gut microbiota analysis of juvenile genetically improved farmed tilapia (Oreochromis niloticus) by dietary supplementation of different resveratrol concentrations

The genetically improved farmed tilapia (GIFT, Oreochromis niloticus) is cultured widely for production of freshwater fish in China, while streptococcosis, likely related to pathogenic infections, occurs frequently in juvenile, mother, and operated GIFT. The gut microbiota plays an important role in nutrient digestibility in animals, and resveratrol (RES) has been used in feed for different freshwater fish species. Therefore, understanding changes in the tilapia gut microbiota across different concentrations of dietary RES supplementation is extremely important. The gut microbiota population in tilapia at 45 d after supplementation with different concentrations (0, 0.025, 0.05, 0.1 g/kg) of dietary RES was assessed by 16S rDNA gene sequencing. A total of 5445 operational taxonomic units were identified from all samples, and 14 phyla and 81 families were identified from all fecal samples. The bacteria of the phylum Firmicutes were significantly enriched in the 0.025 g/kg RES group when compared with the controls. Proteobacteria, Firmicutes and Cyanobacteria were the most dominant three phyla in all samples. With the increasing concentrations, the proportion of beneficial microbial taxa (Acetobacteraceae and Methylobacteriaceae) increased, whereas the proportion of harmful microbial taxa decreased, eg. Streptococcaceae except for 0.1 g/kg RES groups. RES did not affect the richness and diversity in tilapia gut microbiota. These findings provide information on the diversity and differences in GIFT gut microbiota database, and may contribute to developing strategies for management of diseases and long-term sustainability of O. niloticus culture.

Suppression of Arrhythmia by Enhancing Mitochondrial Ca2+ Uptake in Catecholaminergic Ventricular Tachycardia Models

Cardiovascular disease-related deaths frequently arise from arrhythmias, but treatment options are limited due to perilous side effects of commonly used antiarrhythmic drugs. Cardiac rhythmicity strongly depends on cardiomyocyte Ca2+ handling and prevalent cardiac diseases are causally associated with perturbations in intracellular Ca2+ handling. Therefore, intracellular Ca2+ transporters are lead candidate structures for novel and safer antiarrhythmic therapies. Mitochondria and mitochondrial Ca2+ transport proteins are important regulators of cardiac Ca2+ handling. Here we evaluated the potential of pharmacological activation of mitochondrial Ca2+ uptake for the treatment of cardiac arrhythmia. To this aim,we tested substances that enhance mitochondrial Ca2+ uptake for their ability to suppress arrhythmia in a murine model for ryanodine receptor 2 (RyR2)-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT) in vitro and in vivo and in induced pluripotent stem cell-derived cardiomyocytes from a CPVT patient. In freshly isolated cardiomyocytes of RyR2R4496C/WT mice efsevin, a synthetic agonist of the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane, prevented the formation of diastolic Ca2+ waves and spontaneous action potentials. The antiarrhythmic effect of efsevin was abolished by blockade of the mitochondrial Ca2+ uniporter (MCU), but could be reproduced using the natural MCU activator kaempferol. Both mitochondrial Ca2+ uptake enhancers (MiCUps), efsevin and kaempferol, significantly reduced episodes of stress-induced ventricular tachycardia in RyR2R4496C/WT mice in vivo and abolished diastolic, arrhythmogenic Ca2+ events in human iPSC-derived cardiomyocytes.

Resveratrol-Induced Effects on Body Fat Differ Depending on Feeding Conditions

Science constantly seeks to identify new molecules that could be used as dietary functional ingredients in the fight against obesity and its co-morbidities. Among them, polyphenols represent a group of molecules of increasing interest. One of the most widely studied polyphenols is resveratrol (trans-3,4',5-trihydroxystilbene), which has been proposed as an "energy restriction mimetic" because it can exert energy restriction-like effects. The aim of this review is to analyze the effects of resveratrol on obesity under different feeding conditions, such as overfeeding, normal feeding, and energy restriction, in animals and humans. The vast majority of the studies reported have addressed the administration of resveratrol to animals alongside an obesogenic diet. Under these experimental conditions usually a decreased body weight amount was found. To date, studies that focus on the effects of resveratrol under normal feeding or energy restriction conditions in animals and humans are scarcer. In these studies no changes in body fat were reported. After analyzing the results obtained under overfeeding, normal feeding, and energy restriction conditions, it can be stated that resveratrol is useful in reducing body fat accumulation, and thus preventing obesity. Nevertheless, for ethical reasons, these results have been obtained in animals. By contrast, there are no evidences showing the usefulness of this phenolic compound in reducing previously accumulated body fat. Consequently, as of yet, there is not scientific support for proposing resveratrol as a new anti-obesity treatment tool.

Cocoa polyphenols and fiber modify colonic gene expression in rats

Purpose

Cocoa intake has been associated with health benefits, improving cardiovascular function and metabolism, as well as modulating intestinal immune function. The aim of this study was to take an in-depth look into the mechanisms affected by the cocoa intake by evaluating the colonic gene expression after nutritional intervention, and to ascertain the role of the fiber of cocoa in these effects.

Methods

To achieve this, Wistar rats were fed for 3 weeks with either a reference diet, a diet containing 10 % cocoa (C10), a diet based on cocoa fiber (CF) or a diet containing inulin (I). At the end of the study, colon was excised to obtain the RNA to evaluate the differential gene expression by microarray. Results were validated by RT-PCR.

Results

The C10 group was the group with most changes in colonic gene expression, most of them down-regulated but a few in common with the CF diet. The C10 diet significantly up-regulated the expression of Scgb1a1 and Scnn1 g and down-regulated Tac4, Mcpt2, Fcer1a and Fabp1 by twofold, most of them related to lipid metabolism and immune function. The CF and I diets down-regulated the expression of Serpina10 and Apoa4 by twofold. Similar patterns of expression were found by PCR.

Conclusion

Most of the effects attributed to cocoa consumption on genes related to the immune system (B cell and mast cell functionality) and lipid metabolism in the colon tissue were due not only to its fiber content, but also to the possible contribution of polyphenols and other compounds.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-016-1230-0) contains supplementary material, which is available to authorized users.

Melinjo (Gnetum gnemon) extract intake during lactation stimulates hepatic AMP-activated protein kinase in offspring of excessive fructose-fed pregnant rats

Excessive maternal fructose intake during pregnancy and in early postnatal life has metabolic consequences for the offspring. We investigated the effects of melinjo (Gnetum gnemon) extract (MeE) intake during lactation on the expression and phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) in the liver of offspring from excessive fructose-fed pregnant dams. Pregnant Wistar rats received a normal diet and 100g/L fructose solution during gestation ad libitum. At delivery, dams were divided into two groups: a control diet (FC) or a 0.1% MeE-containing diet (FM) fed during lactation. The dams that were not treated with fructose were fed a control diet (CC). At postnatal week 3, some pups were sacrificed, while the remaining continued to receive a normal diet and were sacrificed at week 17. Blood chemistry and phosphorylation levels of AMPK and acetyl-coenzyme A carboxylase (ACC) were evaluated. Plasma glucose levels in FC female offspring increased compared to that receiving CC at weeks 3 and 17; however, the levels in FM female offspring decreased at week 17. The insulin levels in FM female offspring decreased significantly compared to that in FC female offspring at week 3. Hepatic AMPK phosphorylation was upregulated in FM offspring at week 3 and in female, but not male, offspring at week 17. ACC phosphorylation in FM female offspring was upregulated at week 17. Our results suggest that maternal MeE intake during lactation may modulate the hepatic AMPK pathways in female offspring.