Typical Anthocyanin Research Articles

Cyanidin‐3‐O‐glucoside ameliorates hydrogen peroxide‐induced oxidative stress by regulating HMGCR‐mediated cholesterol anabolism in HEK‐293T cells

AbstractCyanidin‐3‐O‐glucoside (C3G), as a typical anthocyanin, exhibits excellent antioxidant effects. This study aimed to demonstrate the role and mechanism of C3G in regulating 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR)‐mediated cholesterol anabolism on H2O2‐induced oxidative stress in HEK‐293T cells. Firstly, the inhibitory effect of C3G on oxidative stress was confirmed by CCK‐8, ROS, and mitochondrial membrane potential (MMP) experiments. Then, proteomics was used to investigate and screen differentially expressed proteins in inhibiting cellular oxidative stress by C3G. HMGCR was screened as a key differentially expressed protein by proteomic analysis. The results verified that C3G could reduce cholesterol levels by inhibiting sterol regulatory element‐binding protein (SREBP2)/HMGCR pathway, increasing ATP, and reducing acetyl‐CoA. Finally, HMGCR had been shown to positively increase ROS accumulation and decrease MMP, which were reversed by intervention of C3G through a series of knockdown and overexpression experiments. In conclusion, the results demonstrated that C3G could inhibit the disorder of cholesterol synthesis in oxidative stress cells by regulating the ROS/SREBP2/HMGCR pathway.

Tonoplast cytochrome b561 is a transmembrane ascorbate-dependent monodehydroascorbate reductase: functional characterization of electron currents in plant vacuoles.

Ascorbate (Asc) is a major redox buffer of plant cells, whose antioxidant activity depends on the ratio with its one-electron oxidation product monodehydroascorbate (MDHA). The cytoplasm contains millimolar concentrations of Asc and soluble enzymes that can regenerate Asc from MDHA or fully oxidized dehydroascorbate. Also, vacuoles contain Asc, but no soluble Asc-regenerating enzymes. Here, we show that vacuoles isolated from Arabidopsis mesophyll cells contain a tonoplast electron transport system that works as a reversible, Asc-dependent transmembrane MDHA oxidoreductase. Electron currents were measured by patch-clamp on isolated vacuoles and found to depend on the availability of Asc (electron donor) and ferricyanide or MDHA (electron acceptors) on opposite sides of the tonoplast. Electron currents were catalyzed by cytochrome b561 isoform A (CYB561A), a tonoplast redox protein with cytoplasmic and luminal Asc binding sites. The Km for Asc of the luminal (4.5 mM) and cytoplasmic site (51 mM) reflected the physiological Asc concentrations in these compartments. The maximal current amplitude was similar in both directions. Mutant plants with impaired CYB561A expression showed no detectable trans-tonoplast electron currents and strong accumulation of leaf anthocyanins under excessive illumination, suggesting a redox-modulation exerted by CYB561A on the typical anthocyanin response to high-light stress.

Cyanidin-3-O-β-glucoside polarizes LPS-induced M1 into M2 Macrophage in J774 cells via PPARγ-mediated NF-κB and STAT6 signaling pathway

• Cy-3-g inhibited inflammation by regulating macrophage polarization. • Cy-3-g polarized LPS-induced M1 toward M2 macrophage. • Cy-3-g regulated M1-M2 polarization via PPARγ-mediated NF-κB and STAT6 signaling pathway. Macrophage polarization exerts critical effect on inflammatory response. Cyanidin-3-O-β-glucoside (Cy-3-g), a typical anthocyanin pigment has been reported to have anti-inflammatory property. However, whether Cy-3-g exerts anti-inflammatory effects by modulating macrophage polarization remains unclear. Lipopolysaccharide (LPS) was used to establish the M1 model of J774 cells, in which the effects of Cy-3-g on M1-M2 conversion were explored. Cy-3-g (1, 10, 100 μM) not only reduced LPS-induced increased expression of proinflammatory factors and but also elevated the levels of anti-inflammatory factors. Moreover, Cy-3-g intervention shifted LPS-polarized M1 into M2, leading to the significant reduction of synthesis of nitric oxide synthase and major histocompatibility complex II (M1 markers), and increase of arginine I and CD206 expression (M2 markers). Further experiments found that Cy-3-g dose-dependently increased peroxisome proliferator-activated receptor-γ (PPARγ) expression. Finally, we determined that Cy-3-g regulated M1-M2 polarization via PPARγ-mediated nuclear factor κB and signal transducers and activators of transcription 6 signaling pathway.

Characterization of the phenolic ripening development of ‘BRS Vitoria’ seedless table grapes using HPLC–DAD–ESI-MS/MS

Determining the harvest date of table grapes is very important to achieve high-quality bunches with adequate soluble solids content, low titratable acidity, and high concentrations of polyphenols. Table grape consumption has increased worldwide due to its phenolic compound content and its beneficial effects on human health. Thus, this study aimed to characterize the phenolic ripening of ‘BRS Vitoria’ seedless table grapes at different ripening stages using HPLC–DAD–ESI-MS/MS. For this purpose, a trial was carried out during 2016 in a commercial vineyard of ‘BRS Vitoria’ seedless grape located in Marialva, state of Parana (Southern Brazil). Berry samples were assessed weekly, starting at véraison until full ripeness. At each ripening stage, the berries were analyzed to determine their physicochemical characteristics and polyphenolic profile. It was observed that ‘BRS Vitoria’ grapes can be harvested approximately 28 days after véraison, when the berries reach soluble solids content higher than 15°Brix and low titratable acidity. The grapes presented a typical anthocyanin profile of hybrid grapes, composed of 3-glucoside and 3,5-diglucoside derivatives. In addition, pelargonidin traces were also observed, and this aglycone is rarely detected in grapes. The total anthocyanin concentration, as malvidin-3,5-diglucoside equivalents, is close to 596.9 mg kg−1. Concerning flavonols, myricetin and quercetin are detected in greater proportions, and this cultivar can also be considered an important source of proanthocyanidins.

Protective effects of cyanidin‐3‐O‐glucoside on UVB‐induced chronic skin photodamage in mice via alleviating oxidative damage and anti‐inflammation

AbstractExcessive ultraviolet (UV) radiation exposure results in skin chronic photodamage via stimulating reactive oxygen species (ROS) and inflammation. Anthocyanins are a group of flavonoids frequently found in edible plants. Cyanidin‐3‐O‐glucoside (C3G) as a typical anthocyanin shows effective anti‐oxidative and anti‐inflammatory properties. This study aims to investigate whether the topical application of C3G moisturizing gel on mice can protect the skin from UVB‐induced chronic photodamage. The results of in vitro experiment showed that the active ingredient C3G can penetrate the mice skin. The dorsal of Kunming mice were treated with C3G moisturizing gel (100, 200, 300 μmol/L) after UVB exposure. The animal experiment demonstrated that C3G can reduce chronic photodamage caused by UVB. C3G could effectively ameliorate the UVB‐induced epidermal barrier dysfunction including an increase in the skin hydration and decrease in the transepidermal water loss, and have statistically significance. Besides, our results also indicated that C3G inhibited UVB‐induced epidermal hyperplasia, the destruction of collagen fibers, ROS levels, and the expression of COX‐2 and IL‐6. In brief, these results indicate that C3G can reduce UVB‐induced chronic photodamage by inhibiting oxidative stress and inflammation.

Sirtuin 6 (SIRT6) Content and Hypoxia‐Inducible Factor 1‐Alpha (HIF‐1α) Expression in Human Umbilical Vein Endothelial Cells (HUVECs) in Response to Cyanidin‐3‐O‐ β‐glucoside (C3G): Pregnancy Complicated by Diabetes (PCD) vs. Normoglycemic Pregnancy (NP)

Diabetes during pregnancy induces chronic hypoxia stress and excessive inflammatory response in placental tissue, particularly evident at the endothelial level. Hypoxia‐inducible factor 1‐alpha (HIF‐1α) is the oxygen‐sensitive subunit of the transcription factor HIF‐1, and its expression is increased in placentas from PCD. SIRT6, a chromatin‐associated protein with both histone deacetylase and mono‐ADP ribosyltransferase enzymatic activities, plays an important role in placental development and homeostasis. SIRT6 is believed to protect cells against oxidative stress, however, this mechanism of action in the human placenta has not been clarified enough. According to recent studies, SIRT6 may act as as a corepressor of the transcription factor HIF1α to control the expression of multiple glycolytic genes to regulate glucose homeostasis. A typical anthocyanin, C3G, a naturally occuring pigment belonging to the group of flavonoids (a subclass of the polyphenol family) was found to be potent SIRT6 activator. The aim of this study was to examine comparatively the effect of C3G on SIRT6 level in HUVECs isolated after PCD (White’s class C) vs. NP. In addition, HIF‐1α expressions were compared. HUVECs were isolated immediately after cesarean section delivery from PCD (N = 24) and NP (N = 24) patients (group I and group II, respectively). The umbilical cord segments was subjected to collagenase digestion and the HUVECs were cultured in vitro under normoxia. Upon reaching confluence, HUVECs were exposed to C3G (0.1, 1.0 and 10 μM) administered into the culture media in the respective subgroups A, B and C during the 7 day period. SIRT6 levels were determined in HUVECs culture lysates obtained in the days 1,3 and 7, using ELISA. After termination of the cultures immunostaining for HIF1α was performer with polyclonal antibody in formalin fixed and paraffin embedded sections. To estimate the mean expression of HIF1α, quantitative immunohostochemistry was applied. The initial HIF1α expression was estimated in the respective controls. After 3 and 7 days of the culture, in both groups the mean SIRT6 levels were significantly (p < 0.05) higher in the subgroups B and C, compared to the initial levels at day 1. However, the mean SIRT6 levels in group I were 5.7‐fold and 2.9‐fold lower (the subgroups B and C, respectively) than observed in euglycemic group II. The initial expression of HIF1α was significantly higher in PCD and amounted to 265% of the average value determned in NP (group II). The mean expression of HIF1α was significantly (p < 0.05) downregulated in group I (the subgroups B and C), whereas in group II was nearly unaffected. These results may suggest potential beneficial effect of SIRT6 activation by C3G in PCD with regard to counteracting oxidative stress and modulation of placental metabolic changes at endothelial level. It is likely that by attenuating HIF1α transcriptional output, SIRT6 promotes mitochondrial oxidative metabolism.Support or Funding InformationWUM grant: 2M2‐W1‐19

Cyanidin-3-O-glucoside protects against cadmium-induced dysfunction of sex hormone secretion via the regulation of hypothalamus-pituitary-gonadal axis in male pubertal mice

Cadmium (Cd) has been generally recognized as an endocrine-disrupting chemical for its toxic effects on the hypothalamus-pituitary-gonadal (HPG) axis accompanied by dysfunction in sex hormone secretion. Particularly, exposure to Cd during puberty versus post-puberty exhibits differing age-dependent effects that require further examination. This study sought to determine if cyanidin-3-O-glucoside (C3G), a typical anthocyanin with neuroprotective bioactivity, could protect against Cd-induced sex hormone-disorder in Pubertal male mice. C3G treatment reversed the disruption of hormone levels and increased Gnrh1 gene expression in the hypothalamus. In addition, the levels of gonadotropins, including luteinizing hormone (LH) and follicle stimulating hormone (FSH), were reversed by C3G. Interestingly, C3G improved the expression of LH and FSH receptor in the testis in mice exposed to Cd. Furthermore, C3G activated the signaling pathway related to the synthesis of testosterone processing. In conclusion, C3G protected against Cd-induced dysfunction of sex hormone secretion through the regulation of the HPG axis in male mice during puberty. The results of this study suggest that consumption of anthocyanins can be protective against metal-induced male reproductive dysfunction.

Cyanidin-3-O-glucoside promotes progesterone secretion by improving cells viability and mitochondrial function in cadmium-sulfate-damaged R2C cells

Cadmium (Cd) is a poisonous metal that is toxic for male reproduction. Cyanidin-3-O-glucoside (C3G) as typical anthocyanin benefits many organs. In this study, we investigated the protective effects and associated underlying mechanisms of C3G against the toxicity of Cd on male reproduction in rat Leydig cell line R2C cells. Cells were pre-protected with C3G (5–160 μmol/L) for 2 h and then treated with cadmium sulfate (CdSO4) (10–160 μmol/L) for 24 h. The results showed that cytotoxicity, mitochondrial damage, superoxide dismutase 2 (SOD2), and overproduction of reactive oxygen species (ROS) in CdSO4-treated R2C cells were significantly reduced with C3G pre-treatment. Moreover, C3G pre-treatment led to upregulated expression of steroidogenic acute regulatory (StAR) protein and progesterone production. Our study suggests that C3G may be a potential therapeutic agent against Cd-induced reproductive toxicity.

Cyanidin-3-O-glucoside inhibits the UVB-induced ROS/COX-2 pathway in HaCaT cells

Ultraviolet (UV) radiation from sunlight, especially UVB (290–320nm), is one of the most important environmental factors that destroys the integrity of the skin and causes epidermal cell apoptosis, potentially even leading to skin cancer. UVB irradiation can cause skin damage by stimulating inflammatory and apoptotic pathways. Anthocyanins are flavonoids that are common in many vegetable foods, and have also demonstrated chemopreventive effects. Cyanidin-3-O-glucoside, as a typical anthocyanin, exhibits anti-inflammatory and anti-oxidant effects. This study aimed to investigate the effects, as well as the underlying mechanisms, of treating UVB-exposed HaCaT cells with Cyanidin-3-O-glucoside. We demonstrated that Cyanidin-3-O-glucoside could effectively prevent the UVB-induced apoptosis of HaCaT cells. This protective effect can be explained by the scavenging of ROS and the suppression of COX-2 expression by interaction with the MAPK and Akt signaling pathways. Furthermore, we used Celecoxib as a positive control, and results showed that Cyanidin-3-O-glucoside was more effective at decreasing EGFR phosphorylation than Celecoxib, which translated into a stronger inhibitory effect against the downstream elements p38, ERK, and JNK. Taken together, these results indicate that Cyanidin-3-O-glucoside can protect HaCaT cells against UVB radiation, which could provide a basis for the development of a potent nutritional therapy for UVB-induced skin disorders.

High concentrations of aromatic acylated anthocyanins found in cauline hairs in Plectranthus ciliatus

Vegetative shoots of a naturalized population of purple-leaved plectranthus (Plectranthus ciliatus, Lamiaceae) were found to contain four main anthocyanins: peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-β-glucopyranoside, peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), and peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-β-glucopyranoside. The first three of these pigments have not been reported previously from any plant. They all follow the typical anthocyanin pattern of Lamiaceae, with universal occurrence of anthocyanidin 3,5-diglucosides and aromatic acylation with p-coumaric and sometimes caffeic acids; however, they differ by being based on peonidin. The four anthocyanins were present in the leaves (22.2 mg g−1 DW), and in the xylem and interfascicular parenchyma of the stem. They were exceptionally abundant, among the highest reported for any plant organ, in epidermal hairs on some of the stem internodes (101 mg g−1 DW). Anthocyanin content in these hairs increased more than three-fold from the youngest to the fourth-youngest internodes. In situ absorbances (λmax ≈ 545 nm) were bathochromic in comparison to absorbances of the isolated anthocyanins in their flavylium form in acidified aqueous solutions (λmax = 525 nm), suggesting that the anthocyanins occur both in quinoidal and flavylium forms in constant proportions in the anthocyanic hair cells. The most distinctive observation with respect to relative proportions of individual anthocyanins was found in de-haired internodes, for which anthocyanin caffeoyl-derivatives decreased, and anthocyanin coumaroyl-derivatives increased, from the youngest to the fourth-youngest internode.

Cyanidin-3-O-β-glucoside inhibits lipopolysaccharide-induced inflammatory response in mouse mastitis model

Cyanidin-3-O-β-glucoside (C3G) (CAS number 7084-24-4), a typical anthocyanin pigment that exists in the human diet, has been reported to have anti-inflammatory properties. However, the effect of C3G on lipopolysaccharide (LPS)-induced mastitis and the molecular mechanisms have not been investigated. In this study, we detected the protective effects of C3G on a LPS-induced mouse mastitis model and investigated the molecular mechanisms in LPS-stimulated mouse mammary epithelial cells (MMECs). Our results showed that C3G could attenuate mammary histopathologic changes and myeloperoxidase activity, and inhibit TNF-α, interleukin (IL)-1β, and IL-6 production caused by LPS. Meanwhile, C3G dose-dependently inhibited TNF-α and IL-6 in LPS-stimulated MMECs. C3G suppressed LPS-induced nuclear factor-κB (NF-κB) and interferon regulatory factor 3 (IRF3) activation. Furthermore, C3G disrupted the formation of lipid rafts by depleting cholesterol. Moreover, C3G activated liver X receptor (LXR)-ABCG1-dependent cholesterol efflux. Knockdown of LXRα abrogated the anti-inflammatory effects of C3G. In conclusion, C3G has a protective effect on LPS-induced mastitis. The promising anti-inflammatory mechanisms of C3G are associated with upregulation of the LXRα-ABCG1 pathway which result in disrupting lipid rafts by depleting cholesterol, thereby suppressing toll-like receptor 4-mediated NF-κB and IRF3 signaling pathways induced by LPS.

Cyanidin-3-O-β-glucoside ameliorates lipopolysaccharide-induced acute lung injury by reducing TLR4 recruitment into lipid rafts

Cyanidin-3-O-β-glucoside (C3G), a typical anthocyanin pigment that exists in the human diet, has been reported to have anti-inflammatory properties. The aim of this study was to detect the effect of C3G on LPS-induced acute lung injury and to investigate the molecular mechanisms. Acute lung injury was induced by intratracheal administration of LPS in mice. Alveolar macrophages from mice were stimulated with LPS and were treated with C3G. Our results showed that C3G attenuated lung histopathologic changes, myeloperoxidase (MPO) activity, TNF-α, IL-1β and IL-6 production in LPS-induced acute lung injury model. In vitro, C3G dose-dependently inhibited TNF-α, IL-1β, IL-6, IL-10 and IFN-β production, as well as NF-κB and IRF3 activation in LPS-stimulated alveolar macrophages. Furthermore, C3G disrupted the formation of lipid rafts by depleting cholesterol and inhibited TLR4 translocation into lipid rafts. Moreover, C3G activated LXRα-ABCG1-dependent cholesterol efflux. Knockout of LXRα abrogated the anti-inflammatory effects of C3G. In conclusion, C3G has a protective effect on LPS-induced acute lung injury. The promising anti-inflammatory mechanisms of C3G is associated with up-regulation of the LXRα-ABCG1 pathway which result in disrupting lipid rafts by depleting cholesterol and reducing translocation of TLR4 to lipid rafts, thereby suppressing TLR4 mediated inflammatory response.

Cyanidin-3-Glucoside Suppresses Cytokine-Induced Inflammatory Response in Human Intestinal Cells: Comparison with 5-Aminosalicylic Acid

The potential use of polyphenols in the prevention and treatment of chronic inflammatory diseases has been extensively investigated although the mechanisms involved in cellular signaling need to be further elucidated. Cyanidin-3-glucoside is a typical anthocyanin of many pigmented fruits and vegetables widespread in the human diet. In the present study, the protection afforded by cyanidin-3-glucoside against cytokine-triggered inflammatory response was evaluated in the human intestinal HT-29 cell line, in comparison with 5-aminosalicylic acid, a well-established anti-inflammatory drug, used in inflammatory bowel disease. For this purpose, some key inflammatory mediators and inflammatory enzymes were examined. Our data showed that cyanidin-3-glucoside reduced cytokine-induced inflammation in intestinal cells, in terms of NO, PGE2 and IL-8 production and of iNOS and COX-2 expressions, at a much lower concentration than 5-aminosalicylic acid, suggesting a higher anti-inflammatory efficiency. Interestingly, cyanidin-3-glucoside and 5-aminosalicylic acid neither prevented IkB-α degradation nor the activation of NF-kB, but significantly reduced cytokine-induced levels of activated STAT1 accumulated in the cell nucleus. In addition, we established that phosphorylated p38 MAPK was not involved in the protective effect of cyanidin-3-glucoside or 5-aminosalicylic acid. Taking into account the high concentrations of dietary anthocyanins potentially reached in the gastrointestinal tract, cyanidin-3-glucoside may be envisaged as a promising nutraceutical giving complementary benefits in the context of inflammatory bowel disease.

Anthocyanin and organic acid profiles of pomegranate (Punica granatum L.) juices from registered varieties in Turkey

SummaryThis is the first study to analyse the profiles of anthocyanin (ACN) and organic acid (OA) and some physico‐chemical properties of pomegranate juices (PJs) obtained from nine registered varieties in Turkey. HPLC analyses revealed that there were significant differences between ACN contents (28–447 mg L−1) and profiles (P < 0.01). The PJs contain maximum six ACNs, 3‐glucosides and 3,5‐diglucoside of delphinidin, cyanidin and pelargonidin. The major OA in PJs was citric acid (66–74%), followed by malic (6–12%), succinic (5–19%), nonidentified (0–14%) and tartaric acids (0.1–3.7%). Amongst individual OAs, citric acid had the most significant effects on TA (r = 0.9761), pH (r = 0.9208) values and sourness of PJs. As different from literature, results of this study revealed that malic acid contents of authentic PJs could be higher than 1.5 g L−1. Consequently, ACN and OA profiles could be successfully used in quality control because all PJs have their own typical ACN and OA profiles.

Anthocyanin fingerprinting for authenticity studies of bilberry (Vaccinium myrtillus L.)

The high valued bilberries of Vaccinium myrtillus L. and the products derived from this berry have been mislabelled and adulterated with substitutes such as synthetic chemical or cheaper berries. Anthocyanin profiles have been successfully used in quality control as all berries have their own typical anthocyanin profile. However, in the case of wild species, the natural variation caused by genetic and environmental differences has to be investigated in order to establish a valid anthocyanin fingerprint. This is the first study to analyse the anthocyanin (aglycone and sugar moiety) profiles of bilberries originating from ten populations from climatically diverse regions of Asian Turkey. We compare the anthocyanin profiles of Turkish bilberries with their previously studied northern European Finnish counterparts with the same optimized RP-HPLC-DAD method.The Turkish bilberries did not significantly differ from their Finnish counterparts in the aglycones, which may be considered as a consistent feature for the identification of V. myrtillus. The results also showed that the sugar moieties were grouped according to the origin. A logistic regression model based on glucoside proportions classified 96.7% of samples correctly into their geographical region of origin.This may be used as a novel discriminating criteria for distinguishing bilberries among different geographical origins. The results demonstrate a basis for a new model and provide information for quality control, label claim verification and raw material source identification of V. myrtillus and related species for industry and regulatory authorities.

Cyanidin-3-O-β-glucoside, a typical anthocyanin, exhibits antilipolytic effects in 3T3-L1 adipocytes during hyperglycemia: Involvement of FoxO1-mediated transcription of adipose triglyceride lipase

Elevated concentrations of circulating free fatty acids (FFAs) have been demonstrated to potentially link obesity, insulin resistance and type 2 diabetes. Inhibition of lipolysis reduces FFAs availability and improves insulin sensitivity. Anthocyanins from different plant foods were shown to improve hyperlipidemia and insulin resistance in vivo. In this study, cyanidin-3-O-β-glucoside (C3G), a typical anthocyanin was selected to examine its in vitro effects on high-glucose-induced lipolysis in cultured 3T3-L1 adipocytes. Incubation with C3G efficiently inhibited FFAs and glycerol release from the adipocytes during hyperglycemia in a dose- and time-dependent manner. C3G treatment also increased the activity of AMP-activated protein kinase, decreased the activity of glutamine:fructose 6-phosphate aminotransferase, reduced cellular UDP-N-acetylglucosamine production, thereby suppressing the hexosamine biosynthetic pathway. In addition, C3G attenuated high-glucose-promoted O-glycosylation of transcription factor FoxO1, resulting in decreased expression of adipose triglyceride lipase (ATGL). Our findings reveal a novel mechanism by which anthocyanin regulates FoxO1-mediated transcription of ATGL and thus inhibits adipocyte lipolysis, suggesting its potential therapeutic application in diabetes-associated hyperlipidemia.

Cyanidin-3-O-β-glucoside regulates fatty acid metabolism via an AMP-activated protein kinase-dependent signaling pathway in human HepG2 cells

BackgroundHepatic metabolic derangements are key components in the development of fatty liver disease. AMP-activated protein kinase (AMPK) plays a central role in controlling hepatic lipid metabolism through modulating the downstream acetyl CoA carboxylase (ACC) and carnitine palmitoyl transferase 1 (CPT-1) pathway. In this study, cyanidin-3-O-β-glucoside (Cy-3-g), a typical anthocyanin pigment was used to examine its effects on AMPK activation and fatty acid metabolism in human HepG2 hepatocytes.ResultsAnthocyanin Cy-3-g increased cellular AMPK activity in a calmodulin kinase kinase dependent manner. Furthermore, Cy-3-g substantially induced AMPK downstream target ACC phosphorylation and inactivation, and then decreased malonyl CoA contents, leading to stimulation of CPT-1 expression and significant increase of fatty acid oxidation in HepG2 cells. These effects of Cy-3-g are largely abolished by pharmacological and genetic inhibition of AMPK.ConclusionThis study demonstrates that Cy-3-g regulates hepatic lipid homeostasis via an AMPK-dependent signaling pathway. Targeting AMPK activation by anthocyanin may represent a promising approach for the prevention and treatment of obesity-related nonalcoholic fatty liver disease.

Cyanidin 3-glucoside attenuates obesity-associated insulin resistance and hepatic steatosis in high-fat diet-fed and db/db mice via the transcription factor FoxO1

Obesity is a major risk factor for the development of type 2 diabetes, and both conditions are now recognized to possess significant inflammatory components underlying their pathophysiologies. Here, we hypothesized that cyanidin 3-glucoside (C3G), a typical anthocyanin reported to possess potent anti-inflammatory properties, would ameliorate obesity-associated inflammation and metabolic disorders, such as insulin resistance and hepatic steatosis in mouse models of diabesity. Male C57BL/6J obese mice fed a high-fat diet for 12 weeks and genetically diabetic db/db mice at an age of 6 weeks received dietary C3G supplementation (0.2%) for 5 weeks. We found that dietary C3G lowered fasting glucose levels and markedly improved the insulin sensitivity in both high-fat diet fed and db/db mice as compared with unsupplemented controls. White adipose tissue messenger RNA levels and serum concentrations of inflammatory cytokines (tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1) were reduced by C3G, as did macrophage infiltration in adipose tissue. Concomitantly, hepatic triglyceride content and steatosis were alleviated by C3G. Moreover, C3G treatment decreased c-Jun N-terminal kinase activation and promoted phosphorylation and nuclear exclusion of forkhead box O1 after refeeding. These findings clearly indicate that C3G has significant potency in antidiabetic effects by modulating the c-Jun N-terminal kinase/forkhead box O1 signaling pathway and the related inflammatory adipocytokines.

Cyanidin 3-glucoside protects 3T3-L1 adipocytes against H2O2- or TNF-α-induced insulin resistance by inhibiting c-Jun NH2-terminal kinase activation

Anthocyanins are naturally occurring plant pigments and exhibit an array of pharmacological properties. Our previous study showed that black rice pigment extract rich in anthocyanin prevents and ameliorates high-fructose-induced insulin resistance in rats. In present study, cyanidin 3-glucoside (Cy-3-G), a typical anthocyanin most abundant in black rice was used to examine its protective effect on insulin sensitivity in 3T3-L1 adipocytes exposed to H2O2 (generated by adding glucose oxidase to the medium) or tumor necrosis factor α (TNF-α). Twelve-hour exposure of 3T3-L1 adipocytes to H2O2 or TNF-α resulted in the increase of c-Jun NH2-terminal kinase (JNK) activation and insulin receptor substrate 1 (IRS1) serine 307 phosphorylation, concomitantly with the decrease in insulin-stimulated IRS1 tyrosine phosphorylation and cellular glucose uptake. Blocking JNK expression using RNA interference efficiently prevented the H2O2- or TNF-α-induced defects in insulin action. Pretreatment of cells with Cy-3-G reduced the intracellular production of reactive oxygen species, the activation of JNK, and attenuated H2O2- or TNF-α-induced insulin resistance in a dose-dependent manner. In parallel, N-acetyl-cysteine, an antioxidant compound, did not exhibit an attenuation of TNF-α-induced insulin resistance. Taken together, these results indicated that Cy-3-G exerts a protective role against H2O2- or TNF-α-induced insulin resistance in 3T3-L1 adipocytes by inhibiting the JNK signal pathway.

Abstracts

Abstracts