Dual mode action of mangiferin in mouse liver under high fat diet

Mango (Mangifera indica L.) By-products in Food Processing and Health Promotion

The edible and nonedible parts of the mango (Mangifera indica L.) contain vitamins, phytocompounds, fiber, and fatty acids. This review highlights the uses of mango by-products in the food industry and their effects on human health. The literature offers many new possibilities for the usage of mango secondary products in the food industry, such as the production of functional foods and bakery products, in addition to the potential for extraction of antioxidants and enzymes. Furthermore, due to their antioxidant and anti-inflammatory properties, the consumption of various mango by-products, in the form of peel and leaf (powder or extract), can improve glycemia, plasma lipid levels, satiety, and endothelial function, suggesting that these compounds can prevent or improve various risk factors for cardiovascular complications and metabolic syndrome. Clinical trials show that the discarded parts of mango fruits and leaves can be used to treat diabetes mellitus, obesity, and cardiovascular disorders. Moreover, mango by-products can be utilized to improve the functional characteristics of foods, may be incorporated as fat replacers, and have the potential to leverage agribusiness and reduce environmental damage resulting from the disposal of discarded materials, in addition to reducing waste and the complex chain of environmental damage. Mango by-products also have the potential to produce nutraceutical food items. The use of new technologies can bring to light the production of numerous products made from by-products, contributing to the development of industrial functional foods. In addition, products for the pharmaceutical and cosmetics industries may also be developed. Nutraceutical and pharmaceutical products could have lower prices and could, therefore, be used by low-income populations. The utilization of mango by-products meets the current trend and growing market for better and healthier products. However, more clinical trials are necessary to evaluate the effectiveness of mango by-products on human health, and new technologies can improve industrial applications.

In-silico study and in-vitro validations for an affinity of mangiferin with aldose reductase: Investigating potential in tackling diabetic retinopathy

Type II Diabetes mellitus (T2DM) and associated complications primarily diabetic retinopathy cases are rising with an alarming rate. Prolong hyperglycemia along with the aldose reductase (AR) activity play a pivotal role in the development of oxidative stress in the aqueous humor and diabetic retinopathy. AR catalyzes conversion of glucose into sorbitol and or fructose get diffuse into lens leading to impaired electrolyte balance and cataract formation. Here in the study, affinity of mangiferin was evaluated first using in silico approaches (Docking studies) and then validated via isothermal titration calorimetry. Here in the present study aim was to check the does mangiferin do have affinity with AR, does mangiferin inhibit the AR and polyol pathway as key pathway involve in the diabetic retinopathy. Both in silico and laboratory investigations were carried out to explore the affinity of mangiferin with the aldose reductase. Swiss target prediction study showed that the AR is prime target of mangiferin in the human proteome. The molecular docking study and affinity searches were performed to seek the bonding pattern and forces involved. Docking (affinity 34.37 kcal/mol) for AR pose 1 was reported superior over the AR pose 2 (affinity -35.46 kcal/mol) against mangiferin. Mangiferin showed significant AR inhibition where IC50 reported 67.711 µg/ml and highest inhibition was reported at 300 µg/ml i.e. 86.44 %. On the contrary, Quercetin showed much higher inhibition of aldose reductase at similar concentration i.e. 94.47 % at 300 µg/ml with IC50 59.6014 µg/ml. Here, AR pose 1 showed higher affinity with the mangiferin and confirmed via Isothermal Titration Calorimetry clearly showed higher binding affinity parameters. Binding affinity of AR pose 1 with the mangiferin was higher as showed with affinity parameter determined via ITC i.e. floating association constant (Ka) reported 6.47×106, binding enthalpy (ΔH) -46.11 kJ/mol and higher binding sites (n) i.e. 1.84. Findings demonstrates that the mangiferin is promising AR inhibitor with the ADME prediction (CLR 1.119 ml/min and t1/2 1.162 h).

Supplementation of Mangiferin to a High-Starch Diet Alleviates Hepatic Injury and Lipid Accumulation Potentially through Modulating Cholesterol Metabolism in Channel Catfish (Ictalurus punctatus)

Starch is a common source of carbohydrates in aqua feed. High-starch diet can cause hepatic injury and lipid accumulation in fish. Mangiferin (MGF) can regulate lipid metabolism and protect the liver, but there is limited research on its effects in fish. In the present study, we investigated whether MGF could ameliorate high-starch-induced hepatic damage and lipid accumulation in channel catfish. The channel catfish (Ictalurus punctatus) were fed one of four experimental diets for eight weeks: a control diet (NCD), a high-starch diet (HCD), an HCD supplemented with 100 mg/kg MGF (100 MGF), and an HCD supplemented with 500 mg/kg MGF (500 MGF). The results demonstrated that the weight gain rate (WGR) (p = 0.031), specific growth rate (SGR) (p = 0.039), and feed conversion efficiency (FCE) (p = 0.040) of the 500 MGF group were significantly higher than those of the NCD group. MGF supplementation alleviated liver damage and improved antioxidant capacity (T-AOC) compared to those of the HCD group (p = 0.000). In addition, dietary MGF significantly reduced plasma glucose (GLU) (p = 0.000), triglyceride (TG) (p= 0.001), and low-density lipoprotein cholesterol (LDL) (p = 0.000) levels. It is noteworthy that MGF significantly reduced the plasma total cholesterol (TC) levels (p = 0.000) and liver TC levels (p = 0.005) of channel catfish. Dietary MGF improves cholesterol homeostasis by decreasing the expression of genes that are involved in cholesterol synthesis and transport (hmgcr, sqle, srebf2, sp1, and ldlr) and increasing the expression of genes that are involved in cholesterol catabolism (cyp7a1). Among them, the largest fold decrease in squalene epoxidase (sqle) expression levels was observed in the 100 MGF or 500 MGF groups compared with the HCD group, with a significant decrease of 3.64-fold or 2.20-fold (p = 0.008). And the 100 MGF or 500 MGF group had significantly decreased (by 1.67-fold or 1.94-fold) Sqle protein levels compared to those of the HCD group (p = 0.000). In primary channel catfish hepatocytes, MGF significantly down-regulated the expression of sqle (p = 0.030) and reduced cholesterol levels (p = 0.000). In NCTC 1469 cells, MGF significantly down-regulated the expression of sqle (p = 0.000) and reduced cholesterol levels (p = 0.024). In conclusion, MGF effectively inhibits sqle expression and reduces cholesterol accumulation. The current study shows how MGF supplementation regulates the metabolism and accumulation of cholesterol in channel catfish, providing a theoretical basis for the use of MGF as a dietary supplement in aquaculture.

Mangiferin, a Potential Supplement to Improve Metabolic Syndrome: Current Status and Future Opportunities

Metabolic syndrome (MetS) represents a considerable clinical and public health burden worldwide. Mangiferin (MF), a flavonoid compound present in diverse species such as mango (Mangifera indica L.), papaya (Pseudocydonia sinensis (Thouin) C. K. Schneid.), zhimu (Anemarrhena asphodeloides Bunge), and honeybush tea (Cyclopia genistoides), boasts a broad array of pharmacological effects. It holds promising uses in nutritionally and functionally targeted foods, particularly concerning MetS treatment. It is therefore pivotal to systematically investigate MF's therapeutic mechanism for MetS and its applications in food and pharmaceutical sectors. This review, with the aid of a network pharmacology approach complemented by this experimental studies, unravels possible mechanisms underlying MF's MetS treatment. Network pharmacology results suggest that MF treats MetS effectively through promoting insulin secretion, targeting obesity and inflammation, alleviating insulin resistance (IR), and mainly operating via the phosphatidylinositol 3 kinase (PI3K)/Akt, nuclear factor kappa-B (NF-[Formula: see text]B), microtubule-associated protein kinase (MAPK), and oxidative stress signaling pathways while repairing damaged insulin signaling. These insights provide a comprehensive framework to understand MF's potential mechanisms in treating MetS. These, however, warrant further experimental validation. Moreover, molecular docking techniques confirmed the plausibility of the predicted outcomes. Hereafter, these findings might form the theoretical bedrock for prospective research into MF's therapeutic potential in MetS therapy.

Mitochondrial Alpha-Keto Acid Dehydrogenase Complexes: Recent Developments on Structure and Function in Health and Disease

The present work delves into the enigmatic world of mitochondrial alpha-keto acid dehydrogenase complexes discussing their metabolic significance, enzymatic operation, moonlighting activities, and pathological relevance with links to underlying structural features. This ubiquitous family of related but diverse multienzyme complexes is involved in carbohydrate metabolism (pyruvate dehydrogenase complex), the citric acid cycle (α-ketoglutarate dehydrogenase complex), and amino acid catabolism (branched-chain α-keto acid dehydrogenase complex, α-ketoadipate dehydrogenase complex); the complexes all function at strategic points and also participate in regulation in these metabolic pathways. These systems are among the largest multienzyme complexes with at times more than 100 protein chains and weights ranging up to ~10 million Daltons. Our chapter offers a wealth of up-to-date information on these multienzyme complexes for a comprehensive understanding of their significance in health and disease.

Mangiferin alleviates trimethylamine-N-oxide (TMAO)-induced atherogenesis and modulates gut microbiota in mice

Trimethylamine-N-oxide (TMAO), originating from dietary trimethylamine-containing nutrients such as choline, has been recognized as a risk factor for atherosclerosis. Mangiferin is a bioactive xanthone initially extracted from mango (Mangifera indica). The present study aimed to investigate the effect of mangiferin on TMAO-induced atherogenesis in mice fed a high-choline diet. Female ApoE-/- mice were randomly divided into three groups and fed either a control diet, a high-choline diet with 1% free choline, or an experimental diet with 1% free choline plus 0.5% mangiferin for 15 weeks. Our results showed that a high-choline diet elevated plasma TMAO levels, accelerated atherogenesis, promoted cholesterol accumulation, and reduced the generation of short-chain fatty acids (SCFAs) by gut microbes. Mangiferin alleviated inflammation, and lowered plasma total cholesterol levels by facilitating the elimination of neutral and acidic sterols in feces, resulting in a 16.7-29.0% reduction in aortic atherosclerotic lesions. Notably, mangiferin could favorably remodel the composition of the gut microbiota by fostering the growth of the beneficial taxa Akkermansia, Parabacteroides, and Bifidobacteriaceae, while reducing the relative abundance of the pathogenic genus Helicobacter. This modulation led to a decrease in plasma lipopolysaccharide levels, enhanced the production of total SCFAs by gut microbes, and reduced susceptibility to atherosclerosis. In conclusion, mangiferin exhibited its ability to alleviate TMAO-induced atherosclerosis through its anti-inflammatory, cholesterol-lowering, and gut microbial modulatory activities.

Mangiferin for the Management of Liver Diseases: A Review

The liver is a digestive and metabolic organ, and several factors can induce liver damage, which is a severe threat to human health. As a natural polyphenolic compound, mangiferin belongs to xanthone glucoside and mainly exists in many plants, such as mango. It is notorious that mangiferin has remarkable pharmacological activities such as anti-inflammatory, anti-tumor, antioxidative stress, antiviral and so on. Emerging evidence indicates the therapeutic benefits of mangiferin against liver disease, including liver injury, nonalcoholic fatty liver disease, alcoholic liver disease, liver fibrosis, and hepatocellular carcinoma. This review aims to summarize the possible underlying signaling mediated by mangiferin in liver disease treatment and the available findings of mangiferin, which can be used to treat different liver diseases and may contribute to mangiferin as a therapeutic agent for liver disease in humans.

The Therapeutic Potential of Vitamins B1, B3 and B6 in Charcot-Marie-Tooth Disease with the Compromised Status of Vitamin-Dependent Processes

Understanding the molecular mechanisms of neurological disorders is necessary for the development of personalized medicine. When the diagnosis considers not only the disease symptoms, but also their molecular basis, treatments tailored to individual patients may be suggested. Vitamin-responsive neurological disorders are induced by deficiencies in vitamin-dependent processes. These deficiencies may occur due to genetic impairments of proteins whose functions are involved with the vitamins. This review considers the enzymes encoded by the DHTKD1, PDK3 and PDXK genes, whose mutations are observed in patients with Charcot-Marie-Tooth (CMT) disease. The enzymes bind or produce the coenzyme forms of vitamins B1 (thiamine diphosphate, ThDP) and B6 (pyridoxal-5'-phosphate, PLP). Alleviation of such disorders through administration of the lacking vitamin or its derivative calls for a better introduction of mechanistic knowledge to medical diagnostics and therapies. Recent data on lower levels of the vitamin B3 derivative, NAD+, in the blood of patients with CMT disease vs. control subjects are also considered in view of the NAD-dependent mechanisms of pathological axonal degeneration, suggesting the therapeutic potential of vitamin B3 in these patients. Thus, improved diagnostics of the underlying causes of CMT disease may allow patients with vitamin-responsive disease forms to benefit from the administration of the vitamins B1, B3, B6, their natural derivatives, or their pharmacological forms.

Cyclopia intermedia (Honeybush) Induces Uncoupling Protein 1 and Peroxisome Proliferator-Activated Receptor Alpha Expression in Obese Diabetic Female db/db Mice

Previously, we reported that a crude polyphenol-enriched fraction of Cyclopia intermedia (CPEF), a plant consumed as the herbal tea, commonly known as honeybush, reduced lipid content in 3T3-L1 adipocytes and inhibited body weight gain in obese, diabetic female leptin receptor-deficient (db/db) mice. In the current study, the mechanisms underlying decreased body weight gain in db/db mice were further elucidated using western blot analysis and in silico approaches. CPEF induced uncoupling protein 1 (UCP1, 3.4-fold, p < 0.05) and peroxisome proliferator-activated receptor alpha (PPARα, 2.6-fold, p < 0.05) expression in brown adipose tissue. In the liver, CPEF induced PPARα expression (2.2-fold, p < 0.05), which was accompanied by a 31.9% decrease in fat droplets in Hematoxylin and Eosin (H&E)-stained liver sections (p < 0.001). Molecular docking analysis revealed that the CPEF compounds, hesperidin and neoponcirin, had the highest binding affinities for UCP1 and PPARα, respectively. This was validated with stabilising intermolecular interactions within the active sites of UCP1 and PPARα when complexed with these compounds. This study suggests that CPEF may exert its anti-obesity effects by promoting thermogenesis and fatty acid oxidation via inducing UCP1 and PPARα expression, and that hesperidin and neoponcirin may be responsible for these effects. Findings from this study could pave the way for designing target-specific anti-obesity therapeutics from C. intermedia.

Mangiferin: the miraculous xanthone with diverse pharmacological properties

Mangiferin (1,3,6,7-tetrahydroxy-2-[3,4,5-trihydroxy-6-(hydroxymethyl) oxan-2-yl] xanthen-9-one) is a bioactive component derived primarily from the mango tree. Belonging to the Xanthone family, its structure allows it to engage with a variety of pharmacological targets. The symmetric linked core of xanthones has a heterogeneous biogenetic background. The carbon atoms are designated in a biochemical order, which reveals the reason of ring A (C1-C4) being referred to as acetate originated, and ring B (C5-C8) is referred to as shikimate originated. The antibacterial, hypocholesterolemic, antiallergic, cardiotonic, antidiabetic, anti-neoplastic, neuroprotective, antioxidant and immunomodulatory properties have all been demonstrated for the secondary metabolite. This study assessed and explained the important medical properties of mangiferin available in published literature, as well as its natural source, biosynthesis, absorption and bioavailability; multiple administration routes; metabolism; nanotechnology for enhanced efficacy of mangiferin and its toxicity, to aid the anticipated on-going potential of mangiferin as a novel diagnostic treatment.

Delayed Impact of 2-Oxoadipate Dehydrogenase Inhibition on the Rat Brain Metabolism Is Linked to Protein Glutarylation

Background

The DHTKD1-encoded 2-oxoadipate dehydrogenase (OADH) oxidizes 2-oxoadipate—a common intermediate of the lysine and tryptophan catabolism. The mostly low and cell-specific flux through these pathways, and similar activities of OADH and ubiquitously expressed 2-oxoglutarate dehydrogenase (OGDH), agree with often asymptomatic phenotypes of heterozygous mutations in the DHTKD1 gene. Nevertheless, OADH/DHTKD1 are linked to impaired insulin sensitivity, cardiovascular disease risks, and Charcot-Marie-Tooth neuropathy. We hypothesize that systemic significance of OADH relies on its generation of glutaryl residues for protein glutarylation. Using pharmacological inhibition of OADH and the animal model of spinal cord injury (SCI), we explore this hypothesis.

Methods

The weight-drop model of SCI, a single intranasal administration of an OADH-directed inhibitor trimethyl adipoyl phosphonate (TMAP), and quantification of the associated metabolic changes in the rat brain employ established methods.

Results

The TMAP-induced metabolic changes in the brain of the control, laminectomized (LE) and SCI rats are long-term and (patho)physiology-dependent. Increased glutarylation of the brain proteins, proportional to OADH expression in the control and LE rats, represents a long-term consequence of the OADH inhibition. The proportionality suggests autoglutarylation of OADH, supported by our mass-spectrometric identification of glutarylated K155 and K818 in recombinant human OADH. In SCI rats, TMAP increases glutarylation of the brain proteins more than OADH expression, inducing a strong perturbation in the brain glutathione metabolism. The redox metabolism is not perturbed by TMAP in LE animals, where the inhibition of OADH increases expression of deglutarylase sirtuin 5. The results reveal the glutarylation-imposed control of the brain glutathione metabolism. Glutarylation of the ODP2 subunit of pyruvate dehydrogenase complex at K451 is detected in the rat brain, linking the OADH function to the brain glucose oxidation essential for the redox state. Short-term inhibition of OADH by TMAP administration manifests in increased levels of tryptophan and decreased levels of sirtuins 5 and 3 in the brain.

Conclusion

Pharmacological inhibition of OADH affects acylation system of the brain, causing long-term, (patho)physiology-dependent changes in the expression of OADH and sirtuin 5, protein glutarylation and glutathione metabolism. The identified glutarylation of ODP2 subunit of pyruvate dehydrogenase complex provides a molecular mechanism of the OADH association with diabetes.

Hypericum Perforatum L. Hairy Root Extracts – Regulation of Glycemic, Metabolic, Serum Enzyme and Lipid Profile in Stz - Induced Diabetic Rats

Apart from currently available therapeutics for the treatment of diabetes mellitus, much attention has been paid to discover phytochemicals from natural resources, mainly due to their low side-effects. Hypericum perforatum hairy root (HR) transformed with Agrobacterium rhizogenes A4 represent prospective experimental system enriched in xanthones, known as potent antidiabetic agents. Thus, the aim of this study was to evaluate HR extracts for their potential antihyperglycemic activity in streptozotocin (STZ)-induced diabetic rats, also compared to the effects of wild-growing Hyperici herba (HH). We conducted an acute-toxicity study, multiple dose study, and 24h blood glucose measurements after a single dose administration of HH and HR (200 mg/kg) in diabetic rats. Furthermore, we examined the effects of 14-days administration of HH and HR extracts on blood glucose levels, metabolic parameters, enzyme, and lipid status in healthy and diabetic rats. Both extracts produced a fall of about 70% in blood glucose level after 24h of administration. Two-week treatment with HH and HR induced a significant decrease (70-72%) in blood glucose levels. Moreover, we found an improvement of the dysregulated metabolic parameters (body weight, food, and water consumption and urine output). Serum enzyme (AST, ALT, and γ-GT) and lipid profile parameters (CHOL, TAG, and HDL) were also improved by both extracts. These findings might provide a new insight for managing diabetic hyperglycemia and dysregulated serum enzyme and lipid profile, using extracts from transgenic roots cultures from H. perforatum.

Fresh Mango Consumption Promotes Greater Satiety and Improves Postprandial Glucose and Insulin Responses in Healthy Overweight and Obese Adults

Mangos are an understudied fruit rich in fiber and polyphenols that have been linked to better metabolic outcomes and promotion of satiety. The purpose of this study was to examine the effect of mango consumption on postprandial glucose, insulin, and satiety responses. Using a randomized crossover study design, 23 overweight and obese men and women consumed 100 kcal snacks of fresh mangos or isocaloric low-fat cookies on two separate occasions. Insulin and satiety hormones were measured at baseline and 45 min post-snack consumption. Glucose was measured at baseline, 30, 60, 90, and 120 min after snack consumption. Satiety questionnaires were completed at baseline and every 20 min for 120 min post-consumption. Both mangos and low-fat cookies increased insulin, with a significantly lower increase for mangos compared with low-fat cookies at 45 min post-snack consumption (P ≤ .05). Glucose increased at 30 min for both snacks; however, the increase was significantly higher for low-fat cookie consumption (P ≤ .05). Cholecystokinin increased after mangos and low-fat cookie consumption (P ≤ .05); however, no differences were detected between the snacks. Adiponectin increased after mango consumption (P ≤ .05) but not after low-fat cookies. Mango consumption reduced hunger, anticipated food consumption and thirst, and increased feelings of fullness (P ≤ .05). Low-fat cookie consumption increased fullness for a shorter time period and did not reduce participants' desire to eat. These results suggest that relative to a refined cookie snack, mangos promote greater satiety and improve postprandial glycemic responses. Future research on long-term effects of mango consumption on food intake, weight control, and glucose homeostasis is warranted. Clinical Trial Registration number: #NCT03957928.

Long Non-coding RNA Signatures Associated With Liver Aging in Senescence-Accelerated Mouse Prone 8 Model

The liver is sensitive to aging because the risk of hepatopathy, including fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma, increases dramatically with age. Long non-coding RNAs (lncRNAs) are >200 nucleotides long and affect many pathological and physiological processes. A potential link was recently discovered between lncRNAs and liver aging; however, comprehensive and systematic research on this topic is still limited. In this study, the mouse liver genome-wide lncRNA profiles of 8-month-old SAMP8 and SAMR1 models were explored through deep RNA sequencing. A total of 605,801,688 clean reads were generated. Among the 2,182 identified lncRNAs, 28 were differentially expressed between SAMP8 and SAMR1 mice. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) surveys showed that these substantially dysregulated lncRNAs participated in liver aging from different aspects, such as lipid catabolic (GO: 0016042) and metabolic pathways. Further assessment was conducted on lncRNAs that are most likely to be involved in liver aging and related diseases, such as LNC_000027, LNC_000204E, NSMUST00000144661.1, and ENSMUST00000181906.1 acted on Ces1g. This study provided the first comprehensive dissection of lncRNA landscape in SAMP8 mouse liver. These lncRNAs could be exploited as potential targets for the molecular-based diagnosis and therapy of age-related liver diseases.

Oral administration of mangiferin ameliorates diabetes in animal models: a meta-analysis and systematic review

Although mangiferin has a number of documented beneficial effects, there are no systematic reviews or meta-analyses of its effects in diabetic animal models. To investigate the effects of oral administration of mangiferin on blood glucose levels, body weight, and total cholesterol and triglycerides levels in diabetic animal models, a meta-analysis was conducted and the underlying mechanisms were reviewed. Studies from 6 databases (PubMed, Web of Science, Embase, Cochrane Library, and CNKI (China National Knowledge Infrastructure), and Wanfang Med) were searched from inception to April 2020. After article screening, a total of 19 articles were included in this meta-analysis. The meta-analysis was performed using RevMan 5.3 and STATA 14.0 software. The overall pooled estimate of standardized mean difference (SMD) of mangiferin's effect on blood glucose was -1.27 (95% confidence interval [CI]: -1.71, -0.82, P < .00001). Body weight increased in lean diabetic animals with an SMD of 1.41 (95% CI: 0.57, 2.25; P = .001), while it decreased in obese diabetic animals with an SMD of -0.92 (95% CI: -1.69, -0.14; P = .02). Mangiferin intake reduced serum total cholesterol and triglycerides levels with SMDs of -1.02 (95% CI: -1.43, -0.61; P < .001) and -1.24 (95% CI: -1.70, -0.79; P < .001), respectively. The meta-analysis suggests that oral intake of mangiferin has a significant antidiabetic effect in animal models, and the systematic review suggested that this function might be attributed to its anti-inflammatory and antioxidative properties, as well as to its function of improving glycolipid metabolism and enhancing insulin signaling.

Isoforms of the DHTKD1-Encoded 2-Oxoadipate Dehydrogenase, Identified in Animal Tissues, Are not Observed upon the Human DHTKD1 Expression in Bacterial or Yeast Systems

Unlike the OGDH-encoded 2-oxoglutarate dehydrogenase (OGDH), which is an essential enzyme present in all animal tissues, expression of the DHTKD1-encoded isoenzyme, 2-oxoadipate dehydrogenase (OADH), depends on a number of factors, and mutant DHTKD1 phenotypes are rarely manifested. Physiological significance of OADH is also obscured by the fact that both isoenzymes transform 2-oxoglutarate and 2-oxoadipate. By analogy with other members of the 2-oxo acid dehydrogenases family, OADH is assumed to be a component of the multienzyme complex that catalyzes oxidative decarboxylation of 2-oxoadipate. This study aims at molecular characterization of OADH from animal tissues. Phylogenetic analysis of 2-oxo acid dehydrogenases reveals OADH only in animals and Dictyostelium discoideum slime mold, within a common branch with bacterial OGDH. Examination of partially purified animal OADH by immunoblotting and mass spectrometry identifies two OADH isoforms with molecular weights of about 130 and 70 kDa. These isoforms are not observed upon the expression of human DHTKD1 protein in either bacterial or yeast system, where the synthesized OADH is of expected molecular weight (about 100 kDa). Thus, the OADH isoforms present in animal tissues, may result from the animal-specific regulation of the DHTKD1 expression and/or posttranslational modifications of the encoded protein. Mapping of the peptides identified in the OADH preparations, onto the protein structure suggests that the 70-kDa isoform is truncated at the N-terminus, but retains the active site. Since the N-terminal domain of OGDH is required for the formation of the multienzyme complex, it is possible that the 70-kDa isoform catalyzes non-oxidative transformation of dicarboxylic 2-oxo acids that does not require the multienzyme structure. In this case, the ratio of the OADH isoforms in animal tissues may correspond to the ratio between the oxidative and non-oxidative decarboxylation of 2-oxoadipate.

Selective Inhibition of 2-Oxoglutarate and 2-Oxoadipate Dehydrogenases by the Phosphonate Analogs of Their 2-Oxo Acid Substrates

Phosphonate analogs of pyruvate and 2-oxoglutarate are established specific inhibitors of cognate 2-oxo acid dehydrogenases. The present work develops application of this class of compounds to specific in vivo inhibition of 2-oxoglutarate dehydrogenase (OGDH) and its isoenzyme, 2-oxoadipate dehydrogenase (OADH). The isoenzymes-enriched preparations from the rat tissues with different expression of OADH and OGDH are used to characterize their interaction with 2-oxoglutarate (OG), 2-oxoadipate (OA) and the phosphonate analogs. Despite a 100-fold difference in the isoenzymes ratio in the heart and liver, similar Michaelis saturations by OG are inherent in the enzyme preparations from these tissues (KmOG = 0.45 ± 0.06 and 0.27 ± 0.026 mM, respectively), indicating no significant contribution of OADH to the OGDH reaction, or similar affinities of the isoenzymes to OG. However, the preparations differ in the catalysis of OADH reaction. The heart preparation, where OADH/OGDH ratio is ≈ 0.01, possesses low-affinity sites to OA (KmOA = 0.55 ± 0.07 mM). The liver preparation, where OADH/OGDH ratio is ≈ 1.6, demonstrates a biphasic saturation with OA: the low-affinity sites (Km,2OA = 0.45 ± 0.12 mM) are similar to those of the heart preparation; the high-affinity sites (Km,1OA = 0.008 ± 0.001 mM), revealed in the liver preparation only, are attributed to OADH. Phosphonate analogs of C5-C7 dicarboxylic 2-oxo acids inhibit OGDH and OADH competitively to 2-oxo substrates in all sites. The high-affinity sites for OA are affected the least by the C5 analog (succinyl phosphonate) and the most by the C7 one (adipoyl phosphonate). The opposite reactivity is inherent in both the low-affinity OA-binding sites and OG-binding sites. The C6 analog (glutaryl phosphonate) does not exhibit a significant preference to either OADH or OGDH. Structural analysis of the phosphonates binding to OADH and OGDH reveals the substitution of a tyrosine residue in OGDH for a serine residue in OADH among structural determinants of the preferential binding of the bulkier ligands to OADH. The consistent kinetic and structural results expose adipoyl phosphonate as a valuable pharmacological tool for specific in vivo inhibition of the DHTKD1-encoded OADH, a new member of mammalian family of 2-oxo acid dehydrogenases, up-regulated in some cancers and associated with diabetes and obesity.

Mangiferin as New Potential Anti-Cancer Agent and Mangiferin-Integrated Polymer Systems-A Novel Research Direction

For a long time, the pharmaceutical industry focused on natural biologically active molecules due to their unique properties, availability and significantly less side-effects. Mangiferin is a naturally occurring C-glucosylxantone that has substantial potential for the treatment of various diseases thanks to its numerous biological activities. Many research studies have proven that mangiferin possesses antioxidant, anti-infection, anti-cancer, anti-diabetic, cardiovascular, neuroprotective properties and it also increases immunity. It is especially important that it has no toxicity. However, mangiferin is not being currently applied to clinical use because its oral bioavailability as well as its absorption in the body are too low. To improve the solubility, enhance the biological action and bioavailability, mangiferin integrated polymer systems have been developed. In this paper, we review molecular mechanisms of anti-cancer action as well as a number of designed polymer-mangiferin systems. Taking together, mangiferin is a very promising anti-cancer molecule with excellent properties and the absence of toxicity.

The Quest to Enhance the Efficacy of Berberine for Type-2 Diabetes and Associated Diseases: Physicochemical Modification Approaches

Berberine is a quaternary isoquinoline alkaloid that has been isolated from numerous plants which are still in use today as medicine and herbal supplements. The great deal of enthusiasm for intense research on berberine to date is based on its diverse pharmacological effects via action on multiple biological targets. Its poor bioavailability resulting from low intestinal absorption coupled with its efflux by the action of P-glycoprotein is, however, the major limitation. In this communication, the chemical approach of improving berberine's bioavailability and pharmacological efficacy is scrutinised with specific reference to type-2 diabetes and associated diseases such as hyperlipidaemia and obesity. The application of modern delivery systems, research from combination studies to preparation of berberine structural hybrids with known biologically active compounds (antidiabetic, antihyperlipidaemic and antioxidant), as well as synthesis approaches of berberine derivative are presented. Improvement of bioavailability and efficacy through in vitro and ex vivo transport studies, as well as animal models of bioavailability/efficacy in lipid metabolism and diabetes targets are discussed.

Synthetic analogues of 2-oxo acids discriminate metabolic contribution of the 2-oxoglutarate and 2-oxoadipate dehydrogenases in mammalian cells and tissues

The biological significance of the DHTKD1-encoded 2-oxoadipate dehydrogenase (OADH) remains obscure due to its catalytic redundancy with the ubiquitous OGDH-encoded 2-oxoglutarate dehydrogenase (OGDH). In this work, metabolic contributions of OADH and OGDH are discriminated by exposure of cells/tissues with different DHTKD1 expression to the synthesized phosphonate analogues of homologous 2-oxodicarboxylates. The saccharopine pathway intermediates and phosphorylated sugars are abundant when cellular expressions of DHTKD1 and OGDH are comparable, while nicotinate and non-phosphorylated sugars are when DHTKD1 expression is order(s) of magnitude lower than that of OGDH. Using succinyl, glutaryl and adipoyl phosphonates on the enzyme preparations from tissues with varied DHTKD1 expression reveals the contributions of OADH and OGDH to oxidation of 2-oxoadipate and 2-oxoglutarate in vitro. In the phosphonates-treated cells with the high and low DHTKD1 expression, adipate or glutarate, correspondingly, are the most affected metabolites. The marker of fatty acid β-oxidation, adipate, is mostly decreased by the shorter, OGDH-preferring, phosphonate, in agreement with the known OGDH dependence of β-oxidation. The longest, OADH-preferring, phosphonate mostly affects the glutarate level. Coupled decreases in sugars and nicotinate upon the OADH inhibition link the perturbation in glucose homeostasis, known in OADH mutants, to the nicotinate-dependent NAD metabolism.

Protein hydrolysate from potato confers hepatic-protection in hamsters against high fat diet induced apoptosis and fibrosis by suppressing Caspase-3 and MMP2/9 and by enhancing Akt-survival pathway

BACKGROUND

A potato protein hydrolysate, APPH is a potential anti-obesity diet ingredient. Since, obesity leads to deterioration of liver function and associated liver diseases, in this study the effect of APPH on high fat diet (HFD) associated liver damages was investigated.

METHODS

Six week old male hamsters were randomly separated to six groups (n = 8) as control, HFD (HFD fed obese), L-APPH (HFD + 15 mg/kg/day of APPH), M-APPH (HFD + 30 mg/kg/day), H-APPH (HFD + 75 mg/kg/day of APPH) and PB (HFD + 500 mg/kg/day of probucol). HFD fed hamsters were administered with APPH 50 days through oral gavage. The animals were euthanized and the number of apoptotic nuclei in liver tissue was determined by TUNEL staining and the extent of interstitial fibrosis was determined by Masson's trichrome staining. Modulation in the molecular events associated with apoptosis and fibrosis were elucidated from the western blotting analysis of the total protein extracts.

RESULTS

Hamsters fed with high fat diet showed symptoms of liver damage as measured from serum markers like alanine aminotransferase and aspartate aminotransferase levels. However a 50 day long supplementation of APPH effectively ameliorated the effects of HFD. HFD also modulated the expression of survival and apoptosis proteins in the hamster liver. Further the HFD groups showed elevated levels of fibrosis markers in liver. The increase in fibrosis and apoptosis was correlated with the increase in the levels of phosphorylated extracellular signal-regulated kinases (pERK1/2) revealing a potential role of ERK in the HFD mediated liver damage. However APPH treatment reduced the effect of HFD on the apoptosis and fibrosis markers considerably and provided hepato-protection.

CONCLUSION

APPH can therefore be considered as an efficient therapeutic agent to ameliorate high fat diet related liver damages.

Xiao Ke Qing improves glycometabolism and ameliorates insulin resistance by regulating the PI3K/Akt pathway in KKAy mice

Xiao Ke Qing (XKQ) granule has been clinically used to treat type 2 diabetes mellitus (T2DM) for 10 years in Chinese traditional medication. However, its mechanisms against hyperglycemia remain poorly understood. This study aims to investigate XKQ mechanisms on diabetes and diabetic liver disease by using the KKAy mice model. Our results indicate that XKQ can significantly reduce food and water intake. XKQ treatment also remarkably decreases both the fasting blood glucose and blood glucose in the oral glucose tolerance test. Additionally, XKQ can significantly decrease the serum alanine aminotransferase level and liver index and can alleviate the fat degeneration in liver tissues. Moreover, XKQ can ameliorate insulin resistance and upregulate the expression of IRS-1, PI3K (p85), p-Akt, and GLUT4 in the skeletal muscle of KKAy mice. XKQ is an effective drug for T2DM by ameliorating insulin resistance and regulating the PI3K/Akt signaling pathway in the skeletal muscle.

Mangiferin: An effective therapeutic agent against several disorders (Review)

Mangiferin (1,3,6,7‑tetrahydroxyxanthone‑C2‑β‑D‑glucoside) is a bioactive ingredient predominantly isolated from the mango tree, with potent antioxidant activity and multifactorial pharmacological effects, including antidiabetic, antitumor, lipometabolism regulating, cardioprotective, anti‑hyperuricemic, neuroprotective, antioxidant, anti‑inflammatory, antipyretic, analgesic, antibacterial, antiviral and immunomodulatory effects. Therefore, it possesses several health‑endorsing properties and is a promising candidate for further research and development. However, low solubility, mucosal permeability and bioavailability restrict the development of mangiferin as a clinical therapeutic, and chemical and physical modification is required to expand its application. This review comprehensively analyzed and collectively summarized the primary pharmacological actions of mangiferin that have been demonstrated in the literature, to support the potential future development of mangiferin as a novel therapeutic drug.

Antihyperuricemic effect of mangiferin aglycon derivative J99745 by inhibiting xanthine oxidase activity and urate transporter 1 expression in mice

A mangiferin aglycon derivative J99745 has been identified as a potent xanthine oxidase (XOD) inhibitor by previous in vitro study. This study aimed to evaluate the hypouricemic effects of J99745 in experimental hyperuricemia mice, and explore the underlying mechanisms. Mice were orally administered 600 mg/kg xanthine once daily for 7 days and intraperitoneally injected 250 mg/kg oxonic acid on the 7th day to induce hyperuricemia. Meanwhile, J99745 (3, 10, and 30 mg/kg), allopurinol (20 mg/kg) or benzbromarone (20 mg/kg) were orally administered to mice for 7 days. On the 7th day, uric acid and creatinine in serum and urine, blood urea nitrogen (BUN), malondialdehyde (MDA) content and XOD activities in serum and liver were determined. Morphological changes in kidney were observed using hematoxylin and eosin (H&E) staining. Hepatic XOD, renal urate transporter 1 (URAT1), glucose transporter type 9 (GLUT9), organic anion transporter 1 (OAT1) and ATP-binding cassette transporter G2 (ABCG2) were detected by Western blot and real time polymerase chain reaction (PCR). The results showed that J99745 at doses of 10 and 30 mg/kg significantly reduced serum urate, and enhanced fractional excretion of uric acid (FEUA). H&E staining confirmed that J99745 provided greater nephroprotective effects than allopurinol and benzbromarone. Moreover, serum and hepatic XOD activities and renal URAT1 expression declined in J99745-treated hyperuricemia mice. In consistence with the ability to inhibit XOD, J99745 lowered serum MDA content in hyperuricemia mice. Our results suggest that J99745 exerts urate-lowering effect by inhibiting XOD activity and URAT1 expression, thus representing a promising candidate as an anti-hyperuricemia agent.

Mangiferin Accelerates Glycolysis and Enhances Mitochondrial Bioenergetics

One of the main causes of hyperglycemia is inefficient or impaired glucose utilization by skeletal muscle, which can be exacerbated by chronic high caloric intake. Previously, we identified a natural compound, mangiferin (MGF) that improved glucose utilization in high fat diet (HFD)-induced insulin resistant mice. To further identify the molecular mechanisms of MGF action on glucose metabolism, we conducted targeted metabolomics and transcriptomics studies of glycolyic and mitochondrial bioenergetics pathways in skeletal muscle. These data revealed that MGF increased glycolytic metabolites that were further augmented as glycolysis proceeded from the early to the late steps. Consistent with an MGF-stimulation of glycolytic flux there was a concomitant increase in the expression of enzymes catalyzing glycolysis. MGF also increased important metabolites in the tricarboxylic acid (TCA) cycle, such as α-ketoglutarate and fumarate. Interestingly however, there was a reduction in succinate, a metabolite that also feeds into the electron transport chain to produce energy. MGF increased succinate clearance by enhancing the expression and activity of succinate dehydrogenase, leading to increased ATP production. At the transcriptional level, MGF induced mRNAs of mitochondrial genes and their transcriptional factors. Together, these data suggest that MGF upregulates mitochondrial oxidative capacity that likely drives the acceleration of glycolysis flux.

In Vitro Bioaccessibility and Effect of Mangifera indica (Ataulfo) Leaf Extract on Induced Dyslipidemia

Cardiovascular diseases (CVDs) are the leading causes of death in the world, and epidemiological evidence points to dietary habits, stress, and obesity as major risk factors promoting pathological conditions like atherosclerosis, hypertension, and thrombosis. Current therapeutic approaches for CVDs rely on lifestyle changes and/or the use of drug agents. However, since the efficacy of such interventions is often limited by poor compliance and/or significant side effects, continued research on new preventive and therapeutic approaches is much needed. Our study is aimed to determine the bioaccessibility, total content of phenolic compounds, and antioxidant capacity (DPPH·, ABTS^·+) of a methanolic extract from Mangifera indica L. leaves (MEM), and its lipid-lowering effect on an induced dyslipidemia model in Wistar rats. Our results showed that mangiferin is the main component of MEM. The extract showed a total content of polyphenol compounds of 575.28 gallic acid equivalents per dry matter basis (GAE/g db), antioxidant activity 77.68 μmol Trolox equivalents per gram (TE/g) db as measured by DPPH· and 20,630 μmol TE/g db by ABTS^·+, and 12% of phenolic compounds were bioaccessible, and 100 mg/kg of MEM reduced hyperlipidemia levels induced in Wistar rats. Further study on the potential use of MEM as a nutraceutical to prevent CVDs in high-fat diet consumers is required.

Antihyperglycemic, antihyperlipidemic and antioxidant effects of standard ethanol extract of Bombax ceiba leaves in high-fat-diet- and streptozotocin-induced Type 2 diabetic rats

The present study aimed at exploring the therapeutic potential of standard extract of Bombax ceiba L. leaves (BCE) in type 2 diabetic mellitus (T2DM). Oral administration of BCE at doses of 70, 140, and 280 mg·kg^-1, to the normal rats and the high-fat-diet- and streptozotocin-induced T2DM rats were carried out. Effects of BCE on blood glucose, body weight, and a range of serum biochemical parameters were tested, and histopathological observation of pancreatic tissues was also performed. HPLC-ESI-Q/TOF-MS/MS analysis indicated that the chemical composition of BCE mainly contained mangiferin, isoorientin, vitexin, isomangiferin, isovitexin, quercetin hexoside, 2'-trans-O-cumaroyl mangiferin, and nigricanside. BCE caused a significant decrease in the concentrations of fasting blood glucose, glycosylated hemoglobin, total cholesterol, triglyceride, low density lipoprotein-cholesterol, serum insulin, and malondialdehyde, and increases in oral glucose tolerance, high density lipoprotein-cholesterol, and superoxide dismutase in the T2DM model rats. Moreover, considerable pancreatic β-cells protection effect and stimulation of insulin secretion from the remaining pancreatic β-cells could be observed after BCE treatment. The results indicated that BCE exhibited an excellent hypoglycemic activity, and alleviated dyslipidemia which is associated with T2DM. Antioxidant activity and protecting pancreatic β-cells are the possible mechanisms involved in anti-diabetic activity of BCE.

Thiamine Induces Long-Term Changes in Amino Acid Profiles and Activities of 2-Oxoglutarate and 2-Oxoadipate Dehydrogenases in Rat Brain

Molecular mechanisms of long-term changes in brain metabolism after thiamine administration (single i.p. injection, 400 mg/kg) were investigated. Protocols for discrimination of the activities of the thiamine diphosphate (ThDP)-dependent 2-oxoglutarate and 2-oxoadipate dehydrogenases were developed to characterize specific regulation of the multienzyme complexes of the 2-oxoglutarate (OGDHC) and 2-oxoadipate (OADHC) dehydrogenases by thiamine. The thiamine-induced changes depended on the brain-region-specific expression of the ThDP-dependent dehydrogenases. In the cerebral cortex, the original levels of OGDHC and OADHC were relatively high and not increased by thiamine, whereas in the cerebellum thiamine upregulated the OGDHC and OADHC activities, whose original levels were relatively low. The effects of thiamine on each of the complexes were different and associated with metabolic rearrangements, which included (i) the brain-region-specific alterations of glutamine synthase and/or glutamate dehydrogenase and NADP+-dependent malic enzyme, (ii) the brain-region-specific changes of the amino acid profiles, and (iii) decreased levels of a number of amino acids in blood plasma. Along with the assays of enzymatic activities and average levels of amino acids in the blood and brain, the thiamine-induced metabolic rearrangements were assessed by analysis of correlations between the levels of amino acids. The set and parameters of the correlations were tissue-specific, and their responses to the thiamine treatment provided additional information on metabolic changes, compared to that gained from the average levels of amino acids. Taken together, the data suggest that thiamine decreases catabolism of amino acids by means of a complex and long-term regulation of metabolic flux through the tricarboxylic acid cycle, which includes coupled changes in activities of the ThDP-dependent dehydrogenases of 2-oxoglutarate and 2-oxoadipate and adjacent enzymes.

Mangiferin: a natural miracle bioactive compound against lifestyle related disorders

The current review article is an attempt to explain the therapeutic potential of mangiferin, a bioactive compound of the mango, against lifestyle-related disorders. Mangiferin (2-β-D-glucopyranosyl-1,3,6,7-tetrahydroxy-9H-xanthen-9-one) can be isolated from higher plants as well as the mango fruit and their byproducts (i.e. peel, seed, and kernel). It possesses several health endorsing properties such as antioxidant, antimicrobial, antidiabetic, antiallergic, anticancer, hypocholesterolemic, and immunomodulatory. It suppresses the activation of peroxisome proliferator activated receptor isoforms by changing the transcription process. Mangiferin protects against different human cancers, including lung, colon, breast, and neuronal cancers, through the suppression of tumor necrosis factor α expression, inducible nitric oxide synthase potential, and proliferation and induction of apoptosis. It also protects against neural and breast cancers by suppressing the expression of matrix metalloproteinase (MMP)-9 and MMP-7 and inhibiting enzymatic activity, metastatic potential, and activation of the β-catenin pathway. It has the capacity to block lipid peroxidation, in order to provide a shielding effect against physiological threats. Additionally, mangiferin enhances the capacity of the monocyte-macrophage system and possesses antibacterial activity against gram-positive and gram-negative bacteria. This review summarizes the literature pertaining to mangiferin and its associated health claims.

Mangiferin protects against adverse skeletal muscle changes and enhances muscle oxidative capacity in obese rats

Obesity-related skeletal muscle changes include muscle atrophy, slow-to-fast fiber-type transformation, and impaired mitochondrial oxidative capacity. These changes relate with increased risk of insulin resistance. Mangiferin, the major component of the plant Mangifera indica, is a well-known anti-inflammatory, anti-diabetic, and antihyperlipidemic agent. This study tested the hypothesis that mangiferin treatment counteracts obesity-induced fiber atrophy and slow-to-fast fiber transition, and favors an oxidative phenotype in skeletal muscle of obese rats. Obese Zucker rats were fed gelatin pellets with (15 mg/kg BW/day) or without (placebo group) mangiferin for 8 weeks. Lean Zucker rats received the same gelatin pellets without mangiferin and served as non-obese and non-diabetic controls. Lesser diameter, fiber composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of myosin-based fiber-types were assessed in soleus and tibialis cranialis muscles. A multivariate discriminant analysis encompassing all fiber-type features indicated that obese rats treated with mangiferin displayed skeletal muscle phenotypes significantly different compared with both lean and obese control rats. Mangiferin significantly decreased inflammatory cytokines, preserved skeletal muscle mass, fiber cross-sectional size, and fiber-type composition, and enhanced muscle fiber oxidative capacity. These data demonstrate that mangiferin attenuated adverse skeletal muscle changes in obese rats.

Mangiferin: A xanthonoid with multipotent anti-inflammatory potential

Over the last era, small molecules sourced from different plants have gained attention for their varied and long-term medicinal benefits. Their advantageous therapeutic effects in diverse pathological complications lead researchers to give an ever-increasing emphasis on them and discover their novel therapeutic potentials. Among these, the heat stable, xanthonoid group of organic molecules has gained special importance with distinctive regards to the bioactive molecule mangiferin due to its solubility in water. Mangiferin, a yellow polyphenol having C-glycosyl xanthone structure, is widely present in different edible sources like mango, and possesses numerous biological activities. Extensive research with this molecule shows its antioxidant, anti-inflammatory, antidiabetic, anticancer, antimicrobial, analgesic, and immunomodulatory properties. Thus, it provides protection against a wide range of physiological disorders. The C-glucosyl linkage and polyhydroxy groups in mangiferin's structure contribute essentially to its free radical-scavenging activity. Moreover, its ability in regulating various transcription factors like NF-κB, Nrf-2, etc. and modulating the expression of different proinflammatory signaling intermediates like tumor necrosis factor-α, COX-2, etc. contribute to its anti-inflammatory, anticancer, and antidiabetic potentials. In this comprehensive article, information has been provided about the sources, chemical structure, metabolism, and different biological activities of mangiferin with special emphasis on the underlying cellular signal transduction pathways. Insights into an in-depth assessment of mangiferin's anti-inflammatory therapeutic potential have also been discussed in detail. On an overall perspective, this review aims to stage mangiferin's diversified therapeutic applications and its emerging possibility as a promising drug in future based on its anti-inflammatory property. © 2016 BioFactors, 42(5):459-474, 2016.

Mangiferin: A review of sources and interventions for biological activities

Xanthones are naturally synthesized in various biological systems such as plants, lichens, and fungi and are stored as by-products. In addition to taxonomic significance they are also important in the treatment/management of a number of human disorders. Mangiferin and its derived lead molecule have never qualified for use in a clinical trial despite a number of pharmacological studies that have proven its effectiveness as an antioxidant, analgesic, antidiabetic, antiproliferative, chemopreventive, radioprotective, cardiotonic, immunomodulatory, and diuretic. For centuries in the traditional practice of medicine in India and China the use of plants containing mangiferin has been a major component for disease management and health benefits. While it resembles biflavones, the C-glucosyl xanthone (mangiferin) has great nutritional and medicinal significance due to its unique structural characteristics. The C-glycoside link of mangiferin, mimicked to nucleophilic phloroglucinol substitution, facilitates its bioavailability and also is responsible for its antioxidant properties. Researchers have also utilized its xanthonic framework for both pharmacophoric backbone and for its use as a substitution group for synthesis and prospects. To date more than 500 derivatives using about 80 reactions have been generated. These reactions include: lipid peroxidation, phosphorylation, glycosylation, methylation, fermentation, deglycosylation, hydrolysis, polymerization, sulfation, acylation, etherification, peroxidation among others. Multiple studies on efficacy and safety have increased the global demand of mangiferin-based food supplements. This review highlights the distribution of mangiferin in plants, its isolation, and assay methods applicable to different sample matrices. In addition we include updates on various strategies and derived products intended for designated pharmacological actions. © 2016 BioFactors, 42(5):504-514, 2016.

Mangiferin modulation of metabolism and metabolic syndrome

The recent emergence of a worldwide epidemic of metabolic disorders, such as obesity and diabetes, demands effective strategy to develop nutraceuticals or pharmaceuticals to halt this trend. Natural products have long been and continue to be an attractive source of nutritional and pharmacological therapeutics. One such natural product is mangiferin (MGF), the predominant constituent of extracts of the mango plant Mangifera indica L. Reports on biological and pharmacological effects of MGF increased exponentially in recent years. MGF has documented antioxidant and anti-inflammatory effects. Recent studies indicate that it modulates multiple biological processes involved in metabolism of carbohydrates and lipids. MGF has been shown to improve metabolic abnormalities and disorders in animal models and humans. This review focuses on the recently reported biological and pharmacological effects of MGF on metabolism and metabolic disorders. © 2016 BioFactors, 42(5):492-503, 2016.

Mangiferin inhibits macrophage classical activation via downregulating interferon regulatory factor 5 expression

Mangiferin is a natural polyphenol and the predominant effective component of Mangifera indica Linn. leaves. For hundreds of years, Mangifera indica Linn. leaf has been used as an ingredient in numerous traditional Chinese medicine preparations for the treatment of bronchitis. However, the pharmacological mechanism of mangiferin in the treatment of bronchitis remains to be elucidated. Macrophage classical activation is important role in the process of bronchial airway inflammation, and interferon regulatory factor 5 (IRF5) has been identified as a key regulatory factor for macrophage classical activation. The present study used the THP-1 human monocyte cell line to investigate whether mangiferin inhibits macrophage classical activation via suppressing IRF5 expression in vitro. THP-1 cells were differentiated to macrophages by phorbol 12-myristate 13-acetate. Macrophages were polarized to M1 macrophages following stimulation with lipopolysaccharide (LPS)/interferon-γ (IFN-γ). Flow cytometric analysis was conducted to detect the M1 macrophages. Reverse transcription-quantitative polymerase chain reaction was used to investigate cellular IRF5 gene expression. Levels of proinflammatory cytokines and IRF5 were assessed following cell culture and cellular homogenization using enzyme-linked immunosorbent assay. IRF5 protein and nuclei co-localization was performed in macrophages with laser scanning confocal microscope immunofluorescence analysis. The results of the present study demonstrated that mangiferin significantly inhibits LPS/IFN-γ stimulation-induced classical activation of macrophages in vitro and markedly decreases proinflammatory cytokine release. In addition, cellular IRF5 expression was markedly downregulated. These results suggest that the inhibitory effect of mangiferin on classical activation of macrophages may be exerted via downregulation of cellular IRF5 expression levels.

The Compound of Mangiferin-Berberine Salt Has Potent Activities in Modulating Lipid and Glucose Metabolisms in HepG2 Cells

The mangiferin-berberine (MB) salt was synthesized by ionic bonding of mangiferin (M) and berberine (B) at an equal molecular ratio. This study aimed to investigate the activities of MB salt in modulating lipid and glucose metabolisms in HepG2 cells. After 24 h treatment of the studying compounds, cellular AMP-activated protein kinase α (AMPKα)/acetyl-CoA carboxylase (ACC) protein levels and carnitine palmitoyltransferase (CPT) 1 activities, intracellular lipid contents, mRNA expression levels of target genes, glucose consumption, and glucose production amounts were determined. Compound C (CC) was used in the blocking experiments. Our results showed that MB salt increased p-AMPKα (Thr172)/p-ACC (Ser79) levels and CPT1 activity and suppressed oleic acid- (OA-) induced lipid accumulation and upregulation of lipogenic genes potently in HepG2 cells. The above activities of MB salt were AMPK dependent and were superior to those of M or B when administered at an equal molar concentration. MB salt enhanced basal and insulin-stimulated glucose consumption and suppressed gluconeogenesis more potently than M or B alone. The inhibiting activity of MB salt on cellular gluconeogenesis was AMPK dependent. Our results may support MB salt as a new kind of agent for the development of novel lipid or glucose-lowering drugs in the future.

Production of superoxide/hydrogen peroxide by the mitochondrial 2-oxoadipate dehydrogenase complex

In humans, mutations in dehydrogenase E1 and transketolase domain containing 1 (DHTKD1) are associated with neurological abnormalities and accumulation of 2-oxoadipate, 2-aminoadipate, and reactive oxygen species. The protein encoded by DHTKD1 has sequence and structural similarities to 2-oxoglutarate dehydrogenase, and the 2-oxoglutarate dehydrogenase complex can produce superoxide/H2O2 at high rates. The DHTKD1 enzyme is hypothesized to catalyze the oxidative decarboxylation of 2-oxoadipate, a shared intermediate of the degradative pathways for tryptophan, lysine and hydroxylysine. Here, we show that rat skeletal muscle mitochondria can produce superoxide/H2O2 at high rates when given 2-oxoadipate. We identify the putative mitochondrial 2-oxoadipate dehydrogenase complex as one of the sources and characterize the conditions that favor its superoxide/H2O2 production. Rates increased at higher NAD(P)H/NAD(P)(+) ratios and were higher at each NAD(P)H/NAD(P)(+) ratio when 2-oxoadipate was present, showing that superoxide/H2O2 was produced during the forward reaction from 2-oxoadipate, but not in the reverse reaction from NADH in the absence of 2-oxoadipate. The maximum capacity of the 2-oxoadipate dehydrogenase complex for production of superoxide/H2O2 is comparable to that of site IF of complex I, and seven, four and almost two-fold lower than the capacities of the 2-oxoglutarate, pyruvate and branched-chain 2-oxoacid dehydrogenase complexes, respectively. Regulation by ADP and ATP of H2O2 production driven by 2-oxoadipate was very different from that driven by 2-oxoglutarate, suggesting that site AF of the 2-oxoadipate dehydrogenase complex is a new source of superoxide/H2O2 associated with the NADH isopotential pool in mitochondria.

Mangiferin supplementation improves serum lipid profiles in overweight patients with hyperlipidemia: a double-blind randomized controlled trial

Our previous studies have shown that mangiferin decreased serum triglycerides and free fatty acids (FFAs) by increasing FFAs oxidation in both animal and cell experiments. This study sought to evaluate the effects of mangiferin on serum lipid profiles in overweight patients with hyperlipidemia. Overweight patients with hyperlipidemia (serum triglyceride ≥ 1.70 mmol/L, and total cholesterol ≥ 5.2 mmol/L) were included in this double-blind randomized controlled trial. Participants were randomly allocated to groups, either receiving mangiferin (150 mg/day) or identical placebo for 12 weeks. The lipid profile and serum levels of mangiferin, glucose, L-carnitine, β-hydroxybutyrate, and acetoacetate were determined at baseline and 12 weeks. A total of 97 participants completed the trial. Compared with the placebo control, mangiferin supplementation significantly decreased the serum levels of triglycerides and FFAs, and insulin resistance index. Mangiferin supplementation also significantly increased the serum levels of mangiferin, high-density lipoprotein cholesterol, L-carnitine, β-hydroxybutyrate, and acetoacetate, and increased lipoprotein lipase activity. However, there were no differences in the serum levels of total cholesterol, low-density lipoprotein cholesterol, serum glucose, and insulin between groups. Mangiferin supplementation could improve serum lipid profiles by reducing serum triglycerides and FFAs in overweight patients with hyperlipidemia, partly due to the promotion of FFAs oxidation.

Beneficial effects of neomangiferin on high fat diet-induced nonalcoholic fatty liver disease in rats

This study was carried out to determine the effect and mechanism of action of neomangiferin (NG) on high-fat diet-induced nonalcoholic fatty liver disease (NAFLD) in rats. NAFLD rats were randomly assigned into several groups of equal number. NG (50, 25mg/kg·day(-1) BW) and lipanthyl (PT, 5mg/kg·day(-1) BW) were given to the NAFLD rats, respectively. In the study, serum lipids, metabolic rate, liver fat, liver lipids and histology were examined. To further investigate the molecular mechanism of the effect of NG on NAFLD, expression levels of mRNA and protein for peroxisome proliferator-activated receptor α (PPARα), fatty acid transport protein 2 (FATP2), long-chain-fatty-acid - CoA ligase 1 (ACSL1) and carnitine palmitoyltransferase 1a (CPT1a) in the liver were determined by Real Time-PCR and western blot analysis, respectively. NG administration significantly reduced the final body weight, liver fat accumulation, and serum triglyceride (TG), total cholesterol (TC) concentrations, low-density lipoprotein cholesterol (LDL-C), glucose (GLU) levels, and hepatic TG, TC, malondialdehyde (MDA) levels, but increased serum high-density lipoprotein cholesterol (HDL-C) and hepatic superoxide dismutase (SOD) levels. NG upregulated the mRNA and protein expression of PPARα and CPT1a, but downregulated the mRNA and protein expression of FATP2 and ACSL1 in the liver. These results suggested that NG can regulate NAFLD partly by modulating the expression levels of genes involved in FFA uptake and lipid oxidation.

Mangiferin stimulates carbohydrate oxidation and protects against metabolic disorders induced by high-fat diets

Excessive dietary fat intake causes systemic metabolic toxicity, manifested in weight gain, hyperglycemia, and insulin resistance. In addition, carbohydrate utilization as a fuel is substantially inhibited. Correction or reversal of these effects during high-fat diet (HFD) intake is of exceptional interest in light of widespread occurrence of diet-associated metabolic disorders in global human populations. Here we report that mangiferin (MGF), a natural compound (the predominant constituent of Mangifera indica extract from the plant that produces mango), protected against HFD-induced weight gain, increased aerobic mitochondrial capacity and thermogenesis, and improved glucose and insulin profiles. To obtain mechanistic insight into the basis for these effects, we determined that mice exposed to an HFD combined with MGF exhibited a substantial shift in respiratory quotient from fatty acid toward carbohydrate utilization. MGF treatment significantly increased glucose oxidation in muscle of HFD-fed mice without changing fatty acid oxidation. These results indicate that MGF redirects fuel utilization toward carbohydrates. In cultured C2C12 myotubes, MGF increased glucose and pyruvate oxidation and ATP production without affecting fatty acid oxidation, confirming in vivo and ex vivo effects. Furthermore, MGF inhibited anaerobic metabolism of pyruvate to lactate but enhanced pyruvate oxidation. A key target of MGF appears to be pyruvate dehydrogenase, determined to be activated by MGF in a variety of assays. These findings underscore the therapeutic potential of activation of carbohydrate utilization in correction of metabolic syndrome and highlight the potential of MGF to serve as a model compound that can elicit fuel-switching effects.

Mangiferin treatment inhibits hepatic expression of acyl-coenzyme A:diacylglycerol acyltransferase-2 in fructose-fed spontaneously hypertensive rats: a link to amelioration of fatty liver

Mangiferin, a xanthone glucoside, and its associated traditional herbs have been demonstrated to improve abnormalities of lipid metabolism. However, its underlying mechanisms remain largely unclear. This study investigated the anti-steatotic effect of mangiferin in fructose-fed spontaneously hypertensive rat (SHR)s that have a mutation in sterol regulatory element binding protein (SREBP)-1. The results showed that co-administration of mangiferin (15 mg/kg, once daily, by oral gavage) over 7 weeks dramatically diminished fructose-induced increases in hepatic triglyceride content and Oil Red O-stained area in SHRs. However, blood pressure, fructose and chow intakes, white adipose tissue weight and metabolic parameters (plasma concentrations of glucose, insulin, triglyceride, total cholesterol and non-esterified fatty acids) were unaffected by mangiferin treatment. Mechanistically, mangiferin treatment suppressed acyl-coenzyme A:diacylglycerol acyltransferase (DGAT)-2 expression at the mRNA and protein levels in the liver. In contrast, mangiferin treatment was without effect on hepatic mRNA and/or protein expression of SREBP-1/1c, carbohydrate response element binding protein, liver pyruvate kinase, fatty acid synthase, acetyl-CoA carboxylase-1, stearoyl-CoA desaturase-1, DGAT-1, monoacyglycerol acyltransferase-2, microsomal triglyceride transfer protein, peroxisome proliferator-activated receptor-alpha, carnitine palmitoyltransferase-1 and acyl-CoA oxidase. Collectively, our results suggest that mangiferin treatment ameliorates fatty liver in fructose-fed SHRs by inhibiting hepatic DGAT-2 that catalyzes the final step in triglyceride biosynthesis. The anti-steatotic effect of mangiferin may occur independently of the hepatic signals associated with de novo fatty acid synthesis and oxidation.