13-Oxo-9(Z),11(E),15(Z)-octadecatrienoic acid activates peroxisome proliferator-activated receptor γ in adipocytes

Metabolome analysis reveals that cyclic adenosine diphosphate ribose contributes to the regulation of differentiation in mice adipocyte

Adipocytes play a key role in energy storage and homeostasis. Although the role of transcription factors in adipocyte differentiation is known, the effect of endogenous metabolites of low molecular weight remains unclear. Here, we analyzed time-dependent changes in the levels of these metabolites throughout adipocyte differentiation, using metabolome analysis, and demonstrated that there is a positive correlation between cyclic adenosine diphosphate ribose (cADPR) and Pparγ mRNA expression used as a marker of differentiation. We also found that the treatment of C3H10T1/2 adipocytes with cADPR increased the mRNA expression of those marker genes and the accumulation of triglycerides. Furthermore, inhibition of ryanodine receptors (RyR), which are activated by cADPR, caused a significant reduction in mRNA expression levels of the marker genes and triglyceride accumulation in adipocytes. Our findings show that cADPR accelerates adipocytic differentiation via RyR pathway.

The global perspective on peroxisome proliferator-activated receptor γ (PPARγ) in ectopic fat deposition: A review

Excessive expansion of adipocytes can have unhealthy consequences as excess free fatty acids enter other tissues and cause ectopic fat deposition by resynthesizing triglycerides. This lipid accumulation in various tissues is harmful and can increase the risk of related metabolic diseases such as type II diabetes, cardiovascular disease, and insulin resistance. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that play a key role in energy metabolism as fatty acid metabolism sensors, and peroxisome proliferator-activated receptor γ (PPARγ) is the main subtype responsible for fat cell differentiation and adipogenesis. In this paper, we introduce the main structure and function of PPARγ and its regulatory role in the process of lipogenesis in the liver, kidney, skeletal muscle, and pancreas. This information can serve as a reference for further understanding the regulatory mechanisms and measures of the PPAR family in the process of ectopic fat deposition.

The Role of α-Linolenic Acid and Its Oxylipins in Human Cardiovascular Diseases

α-linolenic acid (ALA) is an essential C-18 n-3 polyunsaturated fatty acid (PUFA), which can be elongated to longer n-3 PUFAs, such as eicosapentaenoic acid (EPA). These long-chain n-3 PUFAs have anti-inflammatory and pro-resolution effects either directly or through their oxylipin metabolites. However, there is evidence that the conversion of ALA to the long-chain PUFAs is limited. On the other hand, there is evidence in humans that supplementation of ALA in the diet is associated with an improved lipid profile, a reduction in the inflammatory biomarker C-reactive protein (CRP) and a reduction in cardiovascular diseases (CVDs) and all-cause mortality. Studies investigating the cellular mechanism for these beneficial effects showed that ALA is metabolized to oxylipins through the Lipoxygenase (LOX), the Cyclooxygenase (COX) and the Cytochrome P450 (CYP450) pathways, leading to hydroperoxy-, epoxy-, mono- and dihydroxylated oxylipins. In several mouse and cell models, it has been shown that ALA and some of its oxylipins, including 9- and 13-hydroxy-octadecatrienoic acids (9-HOTrE and 13-HOTrE), have immunomodulating effects. Taken together, the current literature suggests a beneficial role for diets rich in ALA in human CVDs, however, it is not always clear whether the described effects are attributable to ALA, its oxylipins or other substances present in the supplemented diets.

Phytochemistry and Pharmacology of Medicinal Plants Used by the Tenggerese Society in Java Island of Indonesia

The archipelagic country of Indonesia is inhabited by 300 ethnic groups, including the indigenous people of Tengger. Based on the reported list of medicinal plants used by the Tengger community, we have reviewed each of them for their phytochemical constituents and pharmacological activities. Out of a total of 41 medicinal plants used by the Tengerrese people, 33 species were studied for their phytochemical and pharmacological properties. More than 554 phytochemicals with diverse molecular structures belonging to different chemical classes including flavonoids, terpenoids, saponins and volatiles were identified from these studied 34 medicinal plants. Many of these medicinal plants and their compounds have been tested for various pharmacological activities including anti-inflammatory, antimicrobial, wound healing, headache, antimalarial and hypertension. Five popularly used medicinal plants by the healers were Garcinia mangostana, Apium graveolens, Cayratia clematidea, Drymocallis arguta and Elaeocarpus longifolius. Only A. graviolens were previously studied, with the outcomes supporting the pharmacological claims to treat hypertension. Few unexplored medicinal plants are Physalis lagascae, Piper amplum, Rosa tomentosa and Tagetes tenuifolia, and they present great potential for biodiscovery and drug lead identification.

Metabolomics reveals inosine 5'-monophosphate is increased during mice adipocyte browning

Adipocyte browning is one of the potential strategies for the prevention of obesity-related metabolic syndromes, but it is a complex process. Although previous studies make it increasingly clear that several transcription factors and enzymes are essential to induce browning, it is unclear what dynamic and metabolic changes occur in induction of browning. Here, we analyzed the effect of a beta-adrenergic receptor agonist (CL316243, accelerator of browning) on metabolic change in mice adipose tissue and plasma using metabolome analysis and speculated that browning is regulated partly by inosine 5′-monophosphate (IMP) metabolism. To test this hypothesis, we investigated whether Ucp-1, a functional marker of browning, mRNA expression is influenced by IMP metabolism using immortalized adipocytes. Our study showed that mycophenolic acid, an IMP dehydrogenase inhibitor, increases the mRNA expression of Ucp-1 in immortalized adipocytes. Furthermore, we performed a single administration of mycophenolate mofetil, a prodrug of mycophenolic acid, to mice and demonstrated that mycophenolate mofetil induces adipocyte browning and miniaturization of adipocyte size, leading to adipose tissue weight loss. These findings showed that IMP metabolism has a significant effect on adipocyte browning, suggesting that the regulator of IMP metabolism has the potential to prevent obesity.

Effect of ω-3 Polyunsaturated Fatty Acids-Derived Bioactive Lipids on Metabolic Disorders

Arachidonic acid (ARA) is an important ω-6 polyunsaturated fatty acid (PUFA), and docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and n-3 docosapentaenoic acid (n-3 DPA) are three well-known ω-3 PUFAs. These fatty acids can be metabolized into a number of bioactive lipids. Eicosanoids derived from ARA have drawn great attention because of their important and complex biofunctions. Although EPA, DHA and n-3 DPA have also shown powerful biofunctions, we have fewer studies of metabolites derived from them than those from ARA. Recently, growing research has focused on the bioaction of ω-3 PUFA-derived metabolites, which indicates their great potential for treating metabolic disorders. Most of the functional studies of these bioactive lipids focused on their anti-inflammatory effects. However, several studies elucidated their direct effects on pancreatic β cells, hepatocytes, adipocytes, skeletal muscle cells, and endothelial cells. These researches revealed the importance of studying the functions of metabolites derived from ω-3 polyunsaturated fatty acids other than themselves. The current review summarizes research into the effects of ω-3 PUFA-derived oxylipins on metabolic disorders, including diabetes, non-alcoholic fatty liver disease, adipose tissue dysfunction, and atherosclerosis.

Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity

Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.

Gut microbial fatty acid metabolites (KetoA and KetoC) affect the progression of nonalcoholic steatohepatitis and reverse cholesterol transport metabolism in mouse model

Nonalcoholic steatohepatitis (NASH) is a common liver disease that occurs in both alcoholics and nonalcoholics. Oxidative stress is a possible causative factor for liver diseases including NASH. Gut microorganisms, especially lactic acid bacteria, can produce unique fatty acids, including hydroxy, oxo, conjugated, and partially saturated fatty acids. The oxo fatty acid 10-oxo-11(E)-octadecenoic acid (KetoC) provides potent cytoprotective effects against oxidative stress through activation of Nrf2-ARE pathway. The aim of this study was to explore the preventive and therapeutic effects of gut microbial fatty acid metabolites in a NASH mouse model. The mice were divided into 3 experimental groups and fed as follows: (1) high-fat diet (HFD) (2) HFD mixed with 0.1% KetoA (10-oxo-12(Z)-octadecenoic acid), and (3) HFD mixed with 0.1% KetoC. After 3 weeks of feeding, plasma parameters, liver histology, and mRNA expression of multiple genes were assessed. There was hardly any difference in fat accumulation in the histological study; however, no ballooning occurred in 2/5 mice of KetoC group. Bridging fibrosis was not observed in the KetoA group, although KetoA administration did not significantly suppress fibrosis score (p = 0.10). In addition, KetoC increased the expression level of HDL related genes and HDL cholesterol levels in the plasma. These results indicated that KetoA and KetoC may partly affect the progression of NASH in mice models.

A review of the studies on food-derived factors which regulate energy metabolism via the modulation of lipid-sensing nuclear receptors

Obesity is one of the most important risk factors for chronic metabolic disorders. Molecular mechanisms underlying obesity-related metabolic disorders have not been completely elucidated. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily and are key metabolic regulators of the whole-body energy metabolism. Certain enzymes involved in carbohydrate and lipid metabolism are directly regulated by PPARs via their interaction with specific response elements in their gene promoters. Many food factors act as ligands of PPARs and regulate carbohydrate and lipid metabolism by regulating the activities of these nuclear receptors, leading to the attenuation of obesity-related metabolic disorders. In this review, we describe our current knowledge of the role of PPARs in the regulation of whole-body energy metabolism and several examples of food factors that act as ligands of PPARs, which may be useful in the management of obesity and the accompanying energy metabolism abnormalities.

Abbreviations: WAT: white adipose tissue; PPAR: Peroxisome proliferators-activated receptor; RXR: retinoid X receptors; mTORC1: mechanistic target of rapamycin complex 1; PPRE: PPAR-responsive regulatory elements; NAFLD: nonalcoholic fatty liver disease; LPL: lipoprotein lipase; FGF21: fibroblast growth factor 21; BAT: brown adipose tissue; UCP1: uncoupling protein 1; LPC(16:0): 1-palmitoyl lysophosphatidylcholine; C/EBP: CCAAT-enhancer binding proteins; STAT5A: signal transduction and activator of transcription 5A; APO apolipoptotein; CBP: cAMP response element-binding protein-binding protein; PGC1A: PPARγ coactivator protein 1a; HFD: high-fat diet; TG: triglyceride; VLDL: very low density lipoprotein; HDL: high density lipoprotein

Silkworms suppress the release of green leaf volatiles by mulberry leaves with an enzyme from their spinnerets

In response to herbivory, plants emit a blend of volatile organic compounds that includes green leaf volatiles (GLVs) and terpenoids. These volatiles are known to attract natural enemies of herbivores and are therefore considered to function as an indirect defense. Selection should favor herbivores that are able to suppress these volatile emissions, and thereby make themselves less conspicuous to natural enemies. We tested this possibility for silkworms, which were observed to leave secretions from their spinnerets while feeding on mulberry leaves. When we ablated the spinnerets of silkworms, no secretions were observed. Leaves infested by intact silkworms released smaller amounts of GLVs than leaves infested by ablated silkworms, indicating that the spinneret secretion suppressed GLV production. This difference in GLV emissions was also reflected in the behavioral response of Zenillia dolosa (Tachinidae), a parasitoid fly of silkworms. The flies laid fewer eggs when exposed to the volatiles from intact silkworm-infested leaves than when exposed to the volatiles from ablated silkworm-infested leaves. We identified a novel enzyme in the secretion from the spinneret that is responsible for the GLV suppression. The enzyme converted 13(S)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoic acid, an intermediate in the biosynthetic pathway of GLVs, into its keto-derivative in a stereospecific manner. Taken together, this study shows that silkworms are able to feed on mulberry in a stealthy manner by suppressing GLV production with an enzyme in secretions of their spinnerets, which might be a countermeasure against induced indirect defense by mulberry plants.

The polyunsaturated fatty acid balance in kidney health and disease: A review

Epidemiological studies show that circulating polyunsaturated fatty acids contribute to preserve renal function. In renal disease states there is generally a lack of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) as measured in biological samples, but despite intense research for more than 30 years, it is still unclear how and to what extent their supplementation would benefit kidney disorders. Studies evaluating the n-6 series and the kidney are less frequent. The last compilation of clinical trials with n-3 LCPUFA supplements focusing on renal function and damage dates back to 2012. We here discuss n-3 and n-6 fatty acids in relation to the kidney summarizing single- and double blind randomized controlled trials performed between 2012 and 2016. Nine were sub-studies/post-hoc analyses of previous parent trials. Twelve out of the twenty trials reported on fatty acid profile or fatty acid species. Factors that may explain inconsistent results obtained after supplementation with the n-3 LCPUFA EPA and DHA in kidney disease are discussed such as baseline levels determining response, drug interaction. The need of evaluating fatty acid status before and after intervention is emphasized, to match changes in outcome measure with changes of any fatty acid potentially involved.

Promise of bitter melon (Momordica charantia) bioactives in cancer prevention and therapy

Recently, there is a paradigm shift that the whole food-derived components are not 'idle bystanders' but actively participate in modulating aberrant metabolic and signaling pathways in both healthy and diseased individuals. One such whole food from Cucurbitaceae family is 'bitter melon' (Momordica charantia, also called bitter gourd, balsam apple, etc.), which has gained an enormous attention in recent years as an alternative medicine in developed countries. The increased focus on bitter melon consumption could in part be due to several recent pre-clinical efficacy studies demonstrating bitter melon potential to target obesity/type II diabetes-associated metabolic aberrations as well as its pre-clinical anti-cancer efficacy against various malignancies. The bioassay-guided fractionations have also classified the bitter melon chemical constituents based on their anti-diabetic or cytotoxic effects. Thus, by definition, these bitter melon constituents are at cross roads on the bioactivity parameters; they either have selective efficacy for correcting metabolic aberrations or targeting cancer cells, or have beneficial effects in both conditions. However, given the vast, though dispersed, literature reports on the bioactivity and beneficial attributes of bitter melon constituents, a comprehensive review on the bitter melon components and the overlapping beneficial attributes is lacking; our review attempts to fulfill these unmet needs. Importantly, the recent realization that there are common risk factors associated with obesity/type II diabetes-associated metabolic aberrations and cancer, this timely review focuses on the dual efficacy of bitter melon against the risk factors associated with both diseases that could potentially impact the course of malignancy to advanced stages. Furthermore, this review also addresses a significant gap in our knowledge regarding the bitter melon drug-drug interactions which can be predicted from the available reports on bitter melon effects on metabolism enzymes and drug transporters. This has important implications, given that a large proportion of individuals, taking bitter melon based supplements/phytochemical extracts/food based home-remedies, are also likely to be taking conventional therapeutic drugs at the same time. Accordingly, the comprehensively reviewed information here could be prudently translated to the clinical implications associated with any potential concerns regarding bitter melon consumption by cancer patients.

Hypolipidemic Effect of Tomato Juice in Hamsters in High Cholesterol Diet-Induced Hyperlipidemia

Tomato is a globally famous food and contains several phytonutrients including lycopene, β-carotene, anthocyanin, and flavonoids. The increased temperature used to produce tomato juice, ketchup, tomato paste and canned tomato enhances the bioactive composition. We aimed to verify the beneficial effects of processed tomato juice from Kagome Ltd. (KOT) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups for treatment: normal (n = 8), standard diet (control); and experimental (n = 32), HCD. The 32 hamsters were further divided into four groups (n = 8 per group) to receive vehicle or KOT by oral gavage at 2787, 5573, or 13,934 mg/kg/day for six weeks, designated the HCD-1X, -2X and -5X groups, respectively. The efficacy and safety of KOT supplementation was evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. KOT supplementation dose-dependently decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. Our study provides experiment-based evidence to support that KOT may be useful in treating or preventing the onset of hyperlipidemia.

Advances in Our Understanding of Oxylipins Derived from Dietary PUFAs

Oxylipins formed from polyunsaturated fatty acids (PUFAs) are the main mediators of PUFA effects in the body. They are formed via cyclooxygenase, lipoxygenase, and cytochrome P450 pathways, resulting in the formation of prostaglandins, thromboxanes, mono-, di-, and tri-hydroxy fatty acids (FAs), epoxy FAs, lipoxins, eoxins, hepoxilins, resolvins, protectins (also called neuroprotectins in the brain), and maresins. In addition to the well-known eicosanoids derived from arachidonic acid, recent developments in lipidomic methodologies have raised awareness of and interest in the large number of oxylipins formed from other PUFAs, including those from the essential FAs and the longer-chain n-3 (ω-3) PUFAs. Oxylipins have essential roles in normal physiology and function, but can also have detrimental effects. Compared with the oxylipins derived from n-3 PUFAs, oxylipins from n-6 PUFAs generally have greater activity and more inflammatory, vasoconstrictory, and proliferative effects, although there are notable exceptions. Because PUFA composition does not necessarily reflect oxylipin composition, comprehensive analysis of the oxylipin profile is necessary to understand the overall physiologic effects of PUFAs mediated through their oxylipins. These analyses should include oxylipins derived from linoleic and α-linolenic acids, because these largely unexplored bioactive oxylipins constitute more than one-half of oxylipins present in tissues. Because collated information on oxylipins formed from different PUFAs is currently unavailable, this review provides a detailed compilation of the main oxylipins formed from PUFAs and describes their functions. Much remains to be elucidated in this emerging field, including the discovery of more oxylipins, and the understanding of the differing biological potencies, kinetics, and isomer-specific activities of these novel PUFA metabolites.