Effects of blueberry anthocyanins on retinal oxidative stress and inflammation in diabetes through Nrf2/HO-1 signaling

Extracts of Digested Berries Increase the Survival of Saccharomyces cerevisiae during H2O2 Induced Oxidative Stress

Many studies suggest anthocyanins may prevent the development of several diseases. However, anthocyanin bioactivity against cellular stress is not fully understood. This study aimed to evaluate the protective effect of berry anthocyanins on stressed cells using Saccharomyces cerevisiae. The impact of in vitro gastrointestinal digestion on anthocyanin profiles was also assessed. Bilberry and blackcurrant had higher anthocyanin levels than raspberry and strawberry, but digestion reduced the detected anthocyanins by approximately 90%. Yeast cells with and without digested or nondigested anthocyanin extracts were exposed to H₂O₂ and examined for survival. In the presence of anthocyanins, particularly from digested strawberry, a significant increase in cell survival was observed, suggesting that the type and levels of anthocyanins are important factors, but they also need to undergo gastrointestinal (GI) structural modifications to induce cell defence. Results also showed that cells need to be exposed to anthocyanins before the stress was applied, suggesting induction of a cellular defence system by anthocyanins or their derivatives rather than by a direct antioxidative effect on H₂O₂. Overall, data showed that exposure of severely stressed yeast cells to digested berry extracts improved cell survival. The findings also showed the importance of considering gastrointestinal digestion when evaluating anthocyanins’ biological activity.

Berries as a Treatment for Obesity-Induced Inflammation: Evidence from Preclinical Models

Inflammation that accompanies obesity is associated with the infiltration of metabolically active tissues by inflammatory immune cells. This propagates a chronic low-grade inflammation associated with increased signaling of common inflammatory pathways such as NF-κB and Toll-like receptor 4 (TLR4). Obesity-associated inflammation is linked to an increased risk of chronic diseases, including type 2 diabetes, cardiovascular disease, and cancer. Preclinical rodent and cell culture studies provide robust evidence that berries and their bioactive components have beneficial effects not only on inflammation, but also on biomarkers of many of these chronic diseases. Berries contain an abundance of bioactive compounds that have been shown to inhibit inflammation and to reduce reactive oxygen species. Therefore, berries represent an intriguing possibility for the treatment of obesity-induced inflammation and associated comorbidities. This review summarizes the anti-inflammatory properties of blackberries, blueberries, strawberries, and raspberries. This review highlights the anti-inflammatory mechanisms of berries and their bioactive components that have been elucidated through the use of preclinical models. The primary mechanisms mediating the anti-inflammatory effects of berries include a reduction in NF-κB signaling that may be secondary to reduced oxidative stress, a down-regulation of TLR4 signaling, and an increase in Nrf2.

The Benefits of Flavonoids in Diabetic Retinopathy

Diabetic retinopathy (DR), one of the most common complications of diabetes, is the leading cause of legal blindness among adults of working age in developed countries. After 20 years of diabetes, almost all patients suffering from type I diabetes mellitus and about 60% of type II diabetics have DR. Several studies have tried to identify drugs and therapies to treat DR though little attention has been given to flavonoids, one type of polyphenols, which can be found in high levels mainly in fruits and vegetables, but also in other foods such as grains, cocoa, green tea or even in red wine. Flavonoids have anti-inflammatory, antioxidant and antiviral effects. Since it is known that diabetes induces oxidative stress and inflammation in the retina leading to neuronal death in the early stages of the disease, the use of these compounds can prove to be beneficial in the prevention or treatment of DR. In this review, we summarize the molecular and cellular effects of flavonoids in the diabetic retina.

Exploring the Applications of the Photoprotective Properties of Anthocyanins in Biological Systems

Due to their physical and chemical characteristics, anthocyanins are amongst the most versatile groups of natural compounds. Such unique signature makes these compounds a focus in several different areas of research. Anthocyanins have well been reported as bioactive compounds in a myriad of health disorders such as cardiovascular diseases, cancer, and obesity, among others, due to their anti-inflammatory, antioxidant, anti-diabetic, anti-bacterial, and anti-proliferative capacities. Such a vast number of action mechanisms may be also due to the number of structurally different anthocyanins plus their related derivatives. In this review, we highlight the recent advances on the potential use of anthocyanins in biological systems with particular focus on their photoprotective properties. Topics such as skin aging and eye degenerative diseases, highly influenced by light, and the action of anthocyanins against such damages will be discussed. Photodynamic Therapy and the potential role of anthocyanins as novel photosensitizers will be also a central theme of this review.

Brás N, Mateus N, de Freitas V, Fernandes I. Anthocyanins as Antidiabetic Agents-In Vitro and In Silico Approaches of Preventive and Therapeutic Effects

Many efforts have been made in the past two decades into the search for novel natural and less-toxic anti-diabetic agents. Some clinical trials have assigned this ability to anthocyanins, although different factors like the food source, the amount ingested, the matrix effect and the time of consumption (before or after a meal) seem to result in contradictory conclusions. The possible mechanisms involved in these preventive or therapeutic effects will be discussed-giving emphasis to the latest in vitro and in silico approaches. Therapeutic strategies to counteract metabolic alterations related to hyperglycemia and Type 2 Diabetes Mellitus (T2DM) may include: (a) Inhibition of carbohydrate-metabolizing enzymes; (b) reduction of glucose transporters expression or activity; (c) inhibition of glycogenolysis and (d) modulation of gut microbiota by anthocyanin breakdown products. These strategies may be achieved through administration of individual anthocyanins or by functional foods containing complexes of anthocyanin:carbohydrate:protein.

Blueberry Extracts as a Novel Approach to Prevent Ozone-Induced Cutaneous Inflammasome Activation

The World Health Organization estimates that 7 million people die every year due to pollution exposure. Among the different pollutants to which living organism are exposed, ozone (O3) represents one of the most toxic, because its location which is the skin is one of the direct tissues exposed to the outdoor environment. Chronic exposure to outdoor stressors can alter cutaneous redox state resulting in the activation of inflammatory pathways. Recently, a new player in the inflammation mechanism was discovered: the multiprotein complex NLRP1 inflammasome, which has been shown to be also expressed in the skin. The topical application of natural compounds has been studied for the last 40 years as a possible approach to prevent and eventually cure skin conditions. Recently, the possibility to use blueberry (BB) extract to prevent pollution-induced skin toxicity has been of great interest in the cosmeceutical industry. In the present study, we analyzed the cutaneous protective effect of BB extract in several skin models (2D, 3D, and human skin explants). Specifically, we observed that in the different skin models used, BB extracts were able to enhance keratinocyte wound closure and normalize proliferation and migration responses previously altered by O3. In addition, pretreatment with BB extracts was able to prevent ozone-induced ROS production and inflammasome activation measured as NRLP1-ASC scaffold formation and also prevent the transcripts of key inflammasome players such as CASP1 and IL-18, suggesting that this approach as a possible new technology to prevent cutaneous pollution damage. Our data support the hypothesis that BB extracts can effectively reduce skin inflammation and be a possible new technology against cutaneous pollution-induced damage.

Neurotoxicity of perfluorooctanoic acid and post-exposure recovery due to blueberry anthocyanins in the planarians Dugesia japonica

Perfluorooctanoic acid (PFOA) is a widely used synthetic industrial chemical which accumulates in ecosystems and organisms. Our study have investigated the neurobehavioral effects of PFOA and the alleviation effects of PFOA-induced neurotoxicity by blueberry anthocyanins (ANT) in Dugesia japonica. The planarians were exposed to PFOA and ANT for ten days. Researchs showed that exposure to PFOA affected locomotor behavior and ANT significantly alleviated the reduction in locomotion induced by PFOA. The regeneration of eyespots and auricles was suppressed by PFOA and was promoted by ANT. Following exposure to PFOA, acetylcholinesterase activity continually decreased and was unaffected in the ANT group, but was elevated after combined administration of PFOA and ANT. Oxidative DNA damage was found in planarians exposed to PFOA and was attenuated after administration of ANT by the alkaline comet assay. Concentrations of three neurotransmitters increased following exposure to PFOA and decreased after administration of ANT. Furthermore, ANT promoted and PFOA inhibited neuronal regeneration. DjotxA, DjotxB, DjFoxG, DjFoxD and Djnlg associated with neural processes were up-regulated following exposure to PFOA. Our findings indicate that PFOA is a neurotoxicant while ANT can attenuate these detrimental effects.

Naturally Derived Heme-Oxygenase 1 Inducers and Their Therapeutic Application to Immune-Mediated Diseases

Heme oxygenase (HO) is the primary antioxidant enzyme involved in heme group degradation. A variety of stimuli triggers the expression of the inducible HO-1 isoform, which is modulated by its substrate and cellular stressors. A major anti-inflammatory role has been assigned to the HO-1 activity. Therefore, in recent years HO-1 induction has been employed as an approach to treating several disorders displaying some immune alterations components, such as exacerbated inflammation or self-reactivity. Many natural compounds have shown to be effective inductors of HO-1 without cytotoxic effects; among them, most are chemicals present in plants used as food, flavoring, and medicine. Here we discuss some naturally derived compounds involved in HO-1 induction, their impact in the immune response modulation, and the beneficial effect in diverse autoimmune disorders. We conclude that the use of some compounds from natural sources able to induce HO-1 is an attractive lifestyle toward promoting human health. This review opens a new outlook on the investigation of naturally derived HO-1 inducers, mainly concerning autoimmunity.

Jabuticaba (Plinia trunciflora (O. Berg) Kausel) improved the lipid profile and immune system and reduced oxidative stress in streptozotocin-induced diabetic rats

The aim of this study was evaluating the effects of jabuticaba aqueous extract (JPE - 0.5 g/kg) on serum lipid levels, immune system, and oxidative stress parameters of streptozotocin-induced diabetic rats. Administration of JPE for 30 days, by gavage, was able to reduce serum levels of total cholesterol, non-high density lipoprotein (HDL) cholesterol, and triglycerides in diabetic rats. The HDL cholesterol levels increased in both diabetic and healthy rats after JPE treatment. Total leukocyte and lymphocyte counts reduced in diabetic rats, and JPE treatment prevented these diabetes mellitus (DM)-induced changes in the immune system. In addition, the induction of DM also led to dysregulation in the activity of superoxide dismutase and catalase antioxidant enzymes as well as an increase in oxidative stress markers. Treatments with JPE reduced oxidative stress and modulated antioxidant enzyme activities. These data demonstrate the potential of JPE as an adjuvant treatment option for diabetic patients. PRACTICAL APPLICATIONS: Considering that it is very common to observe dyslipidemia in diabetic patients and that these alterations, combined with the increased oxidative stress levels, also common in these patients, can lead to the development of cardiovascular diseases, JPE would be an alternative treatment adjunct to reduce these risks. In addition, although more studies are needed, JPE has the potential to improve the count of total lymphocytes and leukocytes, which could assist in improving the immune response of these patients, who also commonly have a higher risk of infectious diseases. Thus, JPE could be used by these patients, in combination with conventional treatment, in the form of a nutraceutical rich in phenolic compounds.

Anthocyanins As Modulators of Cell Redox-Dependent Pathways in Non-Communicable Diseases

Chronic Noncommunicable Diseases (NCDs), mostly represented by cardiovascular diseases, diabetes, chronic pulmonary diseases, cancers, and several chronic pathologies, are one of the main causes of morbidity and mortality, and are mainly related to the occurrence of metabolic risk factors. Anthocyanins (ACNs) possess a wide spectrum of biological activities, such as anti-inflammatory, antioxidant, cardioprotective and chemopreventive properties, which are able to promote human health. Although ACNs present an apparent low bioavailability, their metabolites may play an important role in the in vivo protective effects observed. This article directly addresses the scientific evidences supporting that ACNs could be useful to protect human population against several NCDs not only acting as antioxidant but through their capability to modulate cell redox-dependent signaling. In particular, ACNs interact with the NF-κB and AP-1 signal transduction pathways, which respond to oxidative signals and mediate a proinflammatory effect, and the Nrf2/ARE pathway and its regulated cytoprotective proteins (GST, NQO, HO-1, etc.), involved in both cellular antioxidant defenses and elimination/inactivation of toxic compounds, so countering the alterations caused by conditions of chemical/oxidative stress. In addition, supposed crosstalks could contribute to explain the protective effects of ACNs in different pathological conditions characterized by an altered balance among these pathways. Thus, this review underlines the importance of specific nutritional molecules for human health and focuses on the molecular targets and the underlying mechanisms of ACNs against various diseases.

Update on the Effects of Antioxidants on Diabetic Retinopathy: In Vitro Experiments, Animal Studies and Clinical Trials

Current therapies for diabetic retinopathy (DR) incorporate blood glucose and blood pressure control, vitrectomy, photocoagulation, and intravitreal injections of anti-vascular endothelial growth factors or corticosteroids. Nonetheless, these techniques have not been demonstrated to completely stop the evolution of this disorder. The pathophysiology of DR is not fully known, but there is more and more evidence indicating that oxidative stress is an important mechanism in the progression of DR. In this sense, antioxidants have been suggested as a possible therapy to reduce the complications of DR. In this review we aim to assemble updated information in relation to in vitro experiments, animal studies and clinical trials dealing with the effect of the antioxidants on DR.

Blueberry and cardiovascular disease risk factors: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Cardiovascular disease (CVD) remains an important cause of mortality and morbidity that can be prevented by the consumption of healthy foods. These include blueberry, a dark coloured berry containing extremely high amounts of functional ingredients. We therefore examined the extent to which supplementation with blueberry effects on CVD risk indices.

METHODS

We searched the ISI Web of Science, Scopus, PubMed and Cochrane Library on March 2020 and checked reference lists from primary studies and review articles for any additional studies. No language restrictions were applied. All randomized and controlled clinical trials (RCTs) using blueberry supplements to modify CVD risk factors were included in our analysis.

RESULTS

Mean Difference (MD) was pooled using a random effects model and 11 studies were included in the final analysis. Pooled effect size showed that supplementation with blueberry had a small insignificant effect in reducing plasma triglycerides (MD = -0.27 mmol/l; 95 % CI: -0.57, 0.17, p = 0.06). Although current study found no differences between blueberry and control groups for any other outcomes, subgroup analysis suggested a favourable impact of blueberry on reducing body weight. Significant weight loss was indicated from studies longer with a follow up of more than 6 weeks or with blueberry powder or freeze-dried blueberry.

CONCLUSION

Current evidence is insufficient to show a benefit of blueberry supplements in modifying CVD risk factors across a variety of adult populations. Robust data and larger studies are required to assess potential effects.

Neuroinflammation and oxidative stress act in concert to promote neurodegeneration in the diabetic retina and optic nerve: galectin-3 participation

Diabetes is a lifelong disease characterized by glucose metabolic imbalance, in which low insulin levels or impaired insulin signaling lead to hyperglycemic state. Within 20 years of diabetes progression, 95% of patients will have diabetic retinopathy, the leading cause of visual defects in working-age people worldwide. Although diabetes is considered a microvascular disease, recent studies have shown that neurodegeneration precedes vascular changes within the diabetic visual system, albeit its mechanisms are still under investigation. Neuroinflammation and oxidative stress are intrinsically related phenomena, since macrophage/microglia and astrocytes are the main sources of reactive oxygen species during central nervous system chronic degenerative diseases, and both pathological processes are increased in the visual system during diabetes. The present review will focus on recent findings of the contribution of oxidative stress derived from neuroinflammation in the early neurodegenerative aspects of the diabetic visual system and their relationship with galectin-3.

Potential Protective and Therapeutic Roles of the Nrf2 Pathway in Ocular Diseases: An Update

Nuclear factor- (erythroid-derived 2-) like 2 (Nrf2) is a regulator of many processes of life, and it plays an important role in antioxidant, anti-inflammatory, and antifibrotic responses and in cancer. This review is focused on the potential mechanism of Nrf2 in the occurrence and development of ocular diseases. Also, several Nrf2 inducers, including noncoding RNAs and exogenous compounds, which control the expression of Nrf2 through different pathways, are discussed in ocular disease models and ocular cells, protecting them from dysfunctional changes. Therefore, Nrf2 might be a potential target of protecting ocular cells from various stresses and preventing ocular diseases.

CoPP-Induced-Induced HO-1 Overexpression Alleviates Photoreceptor Degeneration With Rapid Dynamics: A Therapeutic Molecular Against Retinopathy

Purpose

Retinitis pigmentosa (RP) causes progressive photoreceptor degeneration in the retina. The N-methyl-N-nitrosourea (MNU)-administered mouse is used as a chemically induced RP model with rapid progression rate. This study was designed to study heme oxygenase-1 (HO-1) expression in the MNU-administered mice, and to explore the therapeutic effects of cobalt protoporphyrin (CoPP).

Methods

The HO-1 expression in the retina of MNU-administered mice was analyzed. CoPP was injected intravenously into the MNU-administered mice. Subsequently, the CoPP-treated mice were subjected to functional and morphologic examinations.

Results

HO-1 was involved in the MNU-induced photoreceptor degeneration. CoPP treatment enhanced retinal HO-1 expression in the MNU-administered mice. Electroretinogram (ERG) examination and behavioral tests showed that CoPP treatment improved the retinal responsiveness of MNU-administered mice. Histologic analysis and optical coherence tomography (OCT) examination showed that retinal architecture of the CoPP-treated mice was more intact than that of the MNU+vehicle group. Cone photoreceptors in the MNU-administered mice were rescued efficiently by CoPP treatment. Furthermore, multielectrode array (MEA) recording showed that CoPP treatment mitigated the spontaneous firing response, enhanced the light-induced firing response, and preserved the basic configurations of visual signal pathway in the MNU-administered mice. Mechanism studies suggested that CoPP afforded these therapeutic effects by modulating the apoptosis cascades and alleviating the oxidative stress in degenerative retinas.

Conclusions

CoPP alleviated photoreceptor degeneration and rectified the signaling abnormities in MNU-administered mice. CoPP may serve as a potential medication against degenerative retinopathy.

Investigation of expression and influence of CTGF and HO-1 in rats with diabetic retinopathy

The expression and influence mechanism of CTGF and HO-1 in rats with diabetic retinopathy (DR) was investigated. One hundred and thirty male Sprague-Dawley (SD) rats were selected and randomly divided into the control group and DR group, with 65 rats in each group. DR was caused by intraperitoneal injection of streptozotocin in rats in the DR group. There were 55 successful models and 10 failed in the modelling. The successful models were sacrificed at the 2nd, 4th and 6th month, respectively. RT-qPCR technology was used for detection of the expression of CTGF and HO-1 in rat retina in each group, H&E staining for observation of the gradation structure in rat retina and TUNEL method for detection of apoptosis of retinal cells. In the DR group, the retina layers were disordered and a few blood vessels dilated at the 2nd month. In the DR group, the inner membrane of the retina swelled, and the ganglion cells were irregularly arranged at the 4th month. In the DR group, dilatation of the blood vessels was more obvious, the inner membrane edema was more severe, and the arrangement was more irregular at the 6th month. The retinal apoptosis rate of DR rats gradually increased at the 2nd, 4th and 6th month, after which, the CTGF expression gradually increased, but the HO-1 expression gradually decreased in retina in the DR group. However, the mRNA expression of CTGF and HO-1 in the rats at the 2nd, 4th and 6th month in the DR group was higher than that in the control group at the same period. Therefore, CTGF and HO-1 are associated with the occurrence and development of DR in rats and can be considered as targets for the treatment of DR.

Blueberry anthocyanin‑enriched extract ameliorates transverse aortic constriction‑induced myocardial dysfunction via the DDAH1/ADMA/NO signaling pathway in mice

Blueberry anthocyanin‑enriched extract (BAE) has been demonstrated to protect against cardiovascular diseases by activating multiple target genes. The present study investigated the effects of BAE on transverse aortic constriction (TAC)‑induced myocardial dysfunction in mice and explored its possible molecular mechanisms. A total of 30 male mice were divided randomly into control, TAC and TAC + BAE groups. Mice in the TAC + BAE groups were administered BAE by oral gavage for 6 consecutive weeks. Myocardial dysfunction was assessed using echocardiogram, histopathology, TUNEL assay, immunofluorescence staining, reverse transcription‑quantitative PCR and western blot analysis. The results demonstrated that BAE treatment significantly ameliorated heart weight, left ventricular weight, myocardial dysfunction, left ventricular hypertrophy and fibrosis. In addition, BAE treatment alleviated TAC‑induced inflammation, oxidative stress and apoptosis. Notably, BAE treatment markedly reduced asymmetric dimethylarginine (ADMA) concentration and significantly increased dimethylarginine dimethylaminohydrolase 1 (DDAH1) expression and nitric oxide (NO) production. The present data indicated that BAE treatment ameliorated TAC‑induced myocardial dysfunction, oxidative stress, inflammatory response and apoptosis via the DDAH1/ADMA/NO signaling pathway.

Knockdown of ALK7 inhibits high glucose-induced oxidative stress and apoptosis in retinal pigment epithelial cells

Diabetic retinopathy (DR) is one of the diabetic complications associated with hyperglycaemia-mediated oxidative stress. Activin receptor-like kinase 7 (ALK7) has been proven to be a potential therapeutic approach for diabetic cardiomyopathy, which is another diabetic complication. However, the role of ALK7 in DR remains unclear. In the current study, ALK7 was found to be up-regulated in clinical samples from DR patients and high glucose (HG)-induced human retinal pigment epithelial cells (ARPE-19). In vitro studies demonstrated that knockdown of ALK7 in ARPE-19 cells through transfection with siRNA-ALK7 (si-ALK7) improved cell viability in HG-induced ARPE-19 cells. Knockdown of ALK7 suppressed HG-induced reactive oxygen species (ROS) production, as well elevating the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) in ARPE-19 cells. The number of apoptotic cells was significantly decreased after transfection with si-ALK7. ALK7 knockdown also caused a significant decrease in bax expression and an increase in bcl-2 expression in HG-induced ARPE-19 cells. In addition, ALK7 knockdown resulted in remarkable increase in the expressions of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) in ARPE-19 cells in response to HG induction. Taken together, knockdown of ALK7 protected ARPE-19 cells from HG-induced oxidative injury, which might be mediated by the activation of the Nrf2/HO-1 signalling pathway.

Relationships Between Neurodegeneration and Vascular Damage in Diabetic Retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes and constitutes a major cause of vision impairment and blindness in the world. DR has long been described exclusively as a microvascular disease of the eye. However, in recent years, a growing interest has been focused on the contribution of neuroretinal degeneration to the pathogenesis of the disease, and there are observations suggesting that neuronal death in the early phases of DR may favor the development of microvascular abnormalities, followed by the full manifestation of the disease. However, the mediators that are involved in the crosslink between neurodegeneration and vascular changes have not yet been identified. According to our hypothesis, vascular endothelial growth factor (VEGF) could probably be the most important connecting link between the death of retinal neurons and the occurrence of microvascular lesions. Indeed, VEGF is known to play important neuroprotective actions; therefore, in the early phases of DR, it may be released in response to neuronal suffering, and it would act as a double-edged weapon inducing both neuroprotective and vasoactive effects. If this hypothesis is correct, then any retinal stress causing neuronal damage should be accompanied by VEGF upregulation and by vascular changes. Similarly, any compound with neuroprotective properties should also induce VEGF downregulation and amelioration of the vascular lesions. In this review, we searched for a correlation between neurodegeneration and vasculopathy in animal models of retinal diseases, examining the effects of different neuroprotective substances, ranging from nutraceuticals to antioxidants to neuropeptides and others and showing that reducing neuronal suffering also prevents overexpression of VEGF and vascular complications. Taken together, the reviewed evidence highlights the crucial role played by mediators such as VEGF in the relationship between retinal neuronal damage and vascular alterations and suggests that the use of neuroprotective substances could be an efficient strategy to prevent the onset or to retard the development of DR.

Staining of RNA and DNA on electrophoretic gels and in cytology with juice of Vaccinium myrtillus berries

Background

My early results of cytological chromosome staining with berry juice of blueberry or bilberry (Vaccinium myrtillus) was re-evaluated with staining of electrophoretic agarose and polyacrylamide gels, fractionating DNA, RNA, and proteins.

Results

Electrophoretic gels were stained with juice from berries of V. myrtillus, only filtered, or the diluted filtrate was mixed with acetic acid and 2-propanol. The staining starts in 2 min, with the highest intensity over the background usually appearing in about 30 min. The berry juice stains RNA, DNA, and an unidentified contaminant of molar mass 200–700 g. After differentiation of the gel background, the stained zones appear purple or black. The berry juice staining with or without acetic 2-propanol shows sharp RNA and DNA zones on gels in Vis (visible) light, and the berry juice displaces a preceding staining with ethidium bromide. A secondary staining with ethidium bromide is not able to displace the berry juice in nucleic acids. Cytological staining of sectioned mature barley (Hordeum vulgare) grains with Vaccinium myrtillus juice followed by differentiation in dilute acetic acid shows nuclei and apparent RNA storing compartments in the aleurone cells and stains suberin-containing chalazal cells of the grain crease deeply red, which keeps long. The anthocyanins faintly stain some proteins on gels. The preparation of polymers from cytochrome c and myoglobin was described.

Conclusions

The staining molecules of V. myrtillus anthocyanins apparently intercalate in the nucleic acids competing for the sites, which could be intercalated by ethidium bromide. The juice is suggested to have use in the exchange of intercalating toxic molecules from DNA and RNA, in the inactivation of viruses, and phytotherapy. The juice may have a use as a nontoxic stain in cytology.

Polygonatum sibiricum polysaccharide alleviates inflammatory cytokines and promotes glucose uptake in high‑glucose‑ and high‑insulin‑induced 3T3‑L1 adipocytes by promoting Nrf2 expression

Polygonatum sibiricum polysaccharide (PSP) has been shown to alleviate hyperglycemia and reduce oxidative stress to delay the progression of diabetic retinopathy and cataracts. However, its role and underlying mechanisms in regulating type 2 diabetes mellitus (T2DM) remain unclear. Nuclear factor erythroid 2‑related factor 2 (Nrf2) activation plays a protective role in T2DM. The present study focused on the effect of PSP on inflammatory cytokine secretion and Nrf2 expression in the adipocytes of T2DM patients. In this study, high‑glucose‑ and high‑insulin‑induced 3T3‑L1 adipocytes were used to mimic insulin‑resistant (IR)‑3T3‑L1 adipocytes. Furthermore, the effect and underlying mechanisms of PSP on inflammation and glucose uptake in IR‑3T3‑L1 adipocytes were investigated. The present study found that proliferation after 50, 100 and 250 µg/ml PSP treatment had no significant change in normal 3T3‑L1 adipocytes. A total of 50, 100 and 250 µg/ml of PSP also alleviated IL‑1β, IL‑6, and TNF‑α levels and promoted proliferation, glucose uptake, and glucose transporter 4 expression in IR‑3T3‑L1 adipocytes. Furthermore, 50, 100 and 250 µg/ml PSP promoted Nrf2 and HO‑1 expression. However, silencing Nrf2 expression reversed the effect of 100 µg/ml PSP in IR‑3T3‑L1 adipocytes. In conclusion, these results suggest that PSP alleviates inflammatory cytokines and promotes glucose uptake in IR‑3T3‑L1 adipocytes by promoting Nrf2 expression. PSP may be a potential therapeutic agent for T2DM treatment by promoting Nrf2 expression.

Effect of intravitreal and intraperitoneal cyanidin-3-glucoside injection in oxygen-induced retinopathy mouse model

Purpose:

To evaluate the effect of cyanidin-3-glucoside (C3G) in oxygen-induced retinopathy (OIR) mouse model.

Methods:

In this experimental study, 10 C57BL / 6J type mice exposed to room air comprised two control groups (n = 5 each; a negative control and a group receiving intravitreal sterile dimethyl sulfoxide [IVS DMSO]). Thirty C57BL / 6J type mice exposed to 75% ± 2% oxygen from postnatal day 7 to postnatal day 12 comprised the OIR groups. On postnatal day 12, these mice were randomized into six groups (n = 5 each): two OIR control groups (negative control and IVS DMSO), two intravitreal C3G groups (300 and 600 ng/μL), and two intraperitoneal C3G groups (0.05 and 0.1 mg/kg). We quantified neovascularization by counting endothelial cell proliferation on the vitreal side of the inner limiting membrane of the retina and examined histological and ultrastructural changes via light and electron microscopy and apoptosis by terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling.

Results:

The intravitreal C3G groups yielded lower endothelial cell counts compared with the intravitreal DMSO group. The intraperitoneal high-dose group had lower cell counts compared with the OIR control groups. Electron microscopy revealed significantly less mitochondrial dysmorphology in intravitreal groups and the high-dose intraperitoneal mice. We noted no difference in apoptotic cell count between the controls, low-dose intravitreal, and both intraperitoneal groups. However, apoptotic cell count was significantly higher in the high-dose intravitreal group.

Conclusion:

C3G suppresses endothelial cell proliferation in an OIR mouse model, leads to a reduced hyperoxia-induced mitochondrial dysmorphology, but increases apoptotic cell death in high concentrations.

Nutraceuticals for the Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and is characterized by degeneration of retinal neurons and neoangiogenesis, causing a severe threat to vision. Nowadays, the principal treatment options for DR are laser photocoagulation, vitreoretinal surgery, or intravitreal injection of drugs targeting vascular endothelial growth factor. However, these treatments only act at advanced stages of DR, have short term efficacy, and cause side effects. Treatment with nutraceuticals (foods providing medical or health benefits) at early stages of DR may represent a reasonable alternative to act upstream of the disease, preventing its progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DR, reducing both the neural and vascular damage typical of DR. Although most studies are limited to animal models and there is the problem of low bioavailability for many nutraceuticals, the use of these compounds may represent a natural alternative method to standard DR treatments.

Health Benefits of Polyphenols and Carotenoids in Age-Related Eye Diseases

Oxidative stress and inflammation play a critical role in the initiation and progression of age-related ocular abnormalities as cataract, glaucoma, diabetic retinopathy, and macular degeneration. Therefore, phytochemicals with proven antioxidant and anti-inflammatory activities, such as carotenoids and polyphenols, could be of benefit in these diseases. We searched PubMed and Web of Science databases for original studies investigating the benefits of different carotenoids and polyphenols in age-related ophthalmic diseases. Our results showed that several polyphenols (such as anthocyanins, Ginkgo biloba, quercetin, and resveratrol) and carotenoids (such as lutein, zeaxanthin, and mezoxanthin) have shown significant preventive and therapeutic benefits against the aforementioned conditions. The involved mechanisms in these findings include mitigating the production of reactive oxygen species, inhibiting the tumor necrosis factor-α and vascular endothelial growth factor pathways, suppressing p53-dependent apoptosis, and suppressing the production of inflammatory markers, such as interleukin- (IL-) 8, IL-6, IL-1a, and endothelial leucocyte adhesion molecule-1. Consumption of products containing these phytochemicals may be protective against these diseases; however, adequate human data are lacking. This review discusses the role and mechanisms of polyphenols and carotenoids and their possible synergistic effects on the prevention and treatment of age-related eye diseases that are induced or augmented by oxidative stress and inflammation.

Scutellarin Exerts Hypoglycemic and Renal Protective Effects in db/db Mice via the Nrf2/HO-1 Signaling Pathway

This study investigated the hypoglycemic and renal protective effects of scutellarin (SCU) in db/db mice and elucidated the underlying mechanisms. The oral administration of metformin hydrochloride (Met) at 120 mg/kg and SCU at 25, 50, and 100 mg/kg over an eight-week period had hypoglycemic effects, demonstrated by decreases in body weight, blood glucose, food and water intake, and glycated hemoglobin activity and by augmented insulin levels and pyruvate kinase activity in the serum of db/db mice. SCU alleviated dyslipidemia by decreasing the levels of triglycerides and total cholesterol and enhancing the levels of high-density lipoprotein cholesterol in the serum of db/db mice. SCU reversed the overexpression of mRNA of renal damage markers (receptor for advanced glycation end products, neutrophil gelatinase-associated lipocalin, and kidney injury molecule 1), macrophage marker CD11b, and T cell marker CD3 in kidney of db/db mice. Pathological examination confirmed that SCU improved the organ structures of hyperglycemia-damaged livers, kidneys, and pancreas islets. Antibody array assay and enzyme-linked immunosorbent assay were combined to screen and analyze the regulatory effects of SCU on inflammatory factors and oxidative enzymes. SCU exerted anti-inflammatory effects by inhibiting the levels of proinflammatory cytokines (glycogen synthase kinase, intercellular adhesion molecule 2, and interleukin 1β and 2) and promoting anti-inflammatory cytokines (interleukin 4). SCU decreased the reactive oxygen species and malondialdehyde concentrations and increased the activity levels of antioxidative enzymes (superoxide dismutase, glutathione peroxidase, and catalase) in serum and kidneys. Furthermore, SCU upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), which in turn improved heme oxygenase 1 (HO-1), superoxide dismutase 1 and 2, and catalase expression levels in kidneys. The study showed that SCU has at least partial hypoglycemic and renal protective effects in db/db mice, and the mechanism is the modulation of the Nrf2/HO-1 signaling pathway.

Activation of Nrf2 signaling by natural products-can it alleviate diabetes?

Type 2 diabetes mellitus (DM) has reached pandemic proportions and effective prevention strategies are wanted. Its onset is accompanied by cellular distress, the nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor boosting cytoprotective responses, and many phytochemicals activate Nrf2 signaling. Thus, Nrf2 activation by natural products could presumably alleviate DM. We summarize function, regulation and exogenous activation of Nrf2, as well as diabetes-linked and Nrf2-susceptible forms of cellular stress. The reported amelioration of insulin resistance, β-cell dysfunction and diabetic complications by activated Nrf2 as well as the status quo of Nrf2 in precision medicine for DM are reviewed.

NDRG2 suppression as a molecular hallmark of photoreceptor-specific cell death in the mouse retina

Photoreceptor cell death is recognized as the key pathogenesis of retinal degeneration, but the molecular basis underlying photoreceptor-specific cell loss in retinal damaging conditions is virtually unknown. The N-myc downstream regulated gene (NDRG) family has recently been reported to regulate cell viability, in particular NDRG1 has been uncovered expression in photoreceptor cells. Accordingly, we herein examined the potential roles of NDRGs in mediating photoreceptor-specific cell loss in retinal damages. By using mouse models of retinal degeneration and the 661 W photoreceptor cell line, we showed that photoreceptor cells are indeed highly sensitive to light exposure and the related oxidative stress, and that photoreceptor cells are even selectively diminished by phototoxins of the alkylating agent N-Methyl-N-nitrosourea (MNU). Unexpectedly, we discovered that of all the NDRG family members, NDRG2, but not the originally hypothesized NDRG1 or other NDRG subtypes, was selectively expressed and specifically responded to retinal damaging conditions in photoreceptor cells. Furthermore, functional experiments proved that NDRG2 was essential for photoreceptor cell viability, which could be attributed to NDRG2 control of the photo-oxidative stress, and that it was the suppression of NDRG2 which led to photoreceptor cell loss in damaging conditions. More importantly, NDRG2 preservation contributed to photoreceptor-specific cell maintenance and retinal protection both in vitro and in vivo. Our findings revealed a previously unrecognized role of NDRG2 in mediating photoreceptor cell homeostasis and established for the first time the molecular hallmark of photoreceptor-specific cell death as NDRG2 suppression, shedding light on improved understanding and therapy of retinal degeneration.

Boysenberry polyphenol inhibits endothelial dysfunction and improves vascular health

Endothelial cells have an important role in maintaining vascular homeostasis. Age-related disorders (including obesity, diabetes, and hypertension) or aging per se induce endothelial dysfunction that predisposes to the development of atherosclerosis. Polyphenols have been reported to suppress age-related endothelial cell disorders, but their role in vascular function is yet to be determined. We investigated the influence of boysenberry polyphenol on vascular health under metabolic stress in a murine model of dietary obesity. We found that administration of boysenberry polyphenol suppressed production of reactive oxygen species (ROS) and increased production of nitric oxide (NO) in the aorta. It has been reported that p53 induces cellular senescence and has a crucial role in age-related disorders, including heart failure and diabetes. Administration of boysenberry polyphenol significantly reduced the endothelial p53 level in the aorta and ameliorated endothelial cell dysfunction in iliac arteries under metabolic stress. Boysenberry polyphenol also reduced ROS and p53 levels in cultured human umbilical vein endothelial cells (HUVECs), while increasing NO production. Uncoupled endothelial nitric oxide synthase (eNOS monomer) is known to promote ROS production. We found that boysenberry polyphenol reduced eNOS monomer levels both in vivo and in vitro, along with an increase of eNOS dimerization. To investigate the components of boysenberry polyphenol mediating these favorable biological effects, we extracted the anthocyanin fractions. We found that anthocyanins contributed to suppression of ROS and p53, in association with increased NO production and eNOS dimerization. In an ex vivo study, anthocyanins promoted relaxation of iliac arteries from mice with dietary obesity. These findings indicate that boysenberry polyphenol and anthocyanins, a major component of this polyphenol, inhibit endothelial dysfunction and contribute to maintenance of vascular homeostasis.

The intraocular staining potential of anthocyanins and their retinal biocompatibility: a preclinical study

PURPOSE

To perform preclinical studies to determine the efficacy and safety of anthocyanins as stains for the internal limiting membrane (ILM) of the eye.

MATERIALS AND METHODS

Cyanidin (Cya), delphinidin (Del), luteolinidin (Lut), peonidin (Peo) and pelargonidin (Pel) were evaluated. These natural dyes were used to stain the lens capsule and ILM of pig eyes. The effects of these dyes on retinal cell viability was determined using a water-soluble tetrazolium salt assay, and oxidative stress was measured in vitro. Histopathology, in situ TUNEL labelling, transmission electronic microscopy (TEM), and electroretinography (ERG) were performed on rats following the intravitreal and subretinal injection of the neuroprotective dyes.

RESULTS

All anthocyanins stained the lens capsule and ILM of the pigs at a concentration of 1 mg/ml. Del, Lut and Peo were non-toxic and produced survival rates in the ARPE19 and RGC5 cells that were similar to those in control cells. We treated eyes with H₂O₂ and three dyes (Del, Lut, and Peo) to explore the possible neuroprotective effects and observed significantly higher survival rates in the ARPE19 cells treated with Del, Lut or Peo and the RGC5 cells treated with Lut or Peo than those in the control cells. Three dyes were intravitreally and subretinally injected into rats in vivo, and the histology showed mildly disorganized retinal cell layers. TUNEL staining and TEM examinations did not reveal additional toxic effects. Rat ERGs were not altered after intravitreal injections.

CONCLUSIONS

This preclinical study, Del, Lut, and Peo show potential as staining agents and warrant further investigation as vital dyes.

Improvement of Cisplatin-induced renal dysfunction by Schisandra chinensis stems via anti-inflammation and anti-apoptosis effects

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill is a frequently used traditional Chinese medicine, and modern pharmacological research has proven that S. chinensis has antioxidant, anti-hepatotoxity, anti-inflammatory, and anti-nephrotoxic effects. Cisplatin is widely used as antineoplastic drug at present, but the clinical application is limited owing to its nephrotoxicity.

AIM OF THE STUDY

To demonstrate the renoprotective activity of the extract of the stems of S. chinensis (SCE) in mice established by cisplatin-triggering acute kidney injury (AKI). The possible molecular mechanism of nephroprotection exhibited by SCE was evaluated for the first time.

MATERIALS AND METHODS

Mice in SCE groups were pre-treated with SCE for 10 consecutive days, and on 7th day 1 h after final administration, following intraperitoneal injection of cisplatin with 20 mg/kg was treated to cisplatin group and SCE groups. On the 10th day, renal function, histopathological change, and oxidative stress markers were investigated.

RESULTS

Renal oxidative stress level characterized by elevated heme oxygenase 1 (HO-1), cytochrome P450 E1 (CYP2E1) and 4-hydroxynonenal (4-HNE) expression was obviously reduced by SCE pre-treatment. In addition, SCE was found to suppress inflammatory response through the reduction of nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) expression and nuclear factor-kappa B (NF-κB) p65 activation. SCE treatment also inhibited activation of apoptotic pathways through down-regulating Bax, cleaved caspase-3, 8, 9 and up-regulating Bcl-2 expression levels.

CONCLUSION

These findings illustrated that SCE possessed powerful protective effect on AKI caused by cisplatin via amelioration of oxidative stress, inflammation and apoptosis.

Dihydromyricetin inhibits NLRP3 inflammasome-dependent pyroptosis by activating the Nrf2 signaling pathway in vascular endothelial cells

Increasing evidence demonstrates that pyroptosis, pro-inflammatory programmed cell death, is linked to atherosclerosis; however, the underlying mechanisms remain to be elucidated. Dihydromyricetin (DHM), a natural flavonoid, was reported to exert anti-oxidative and anti-inflammatory bioactivities. However, the effect of DHM on atherosclerosis-related pyroptosis has not been studied. In the present study, palmitic acid (PA) treatment led to pyroptosis in human umbilical vein endothelial cells (HUVECs), as evidenced by caspase-1 activation, LDH release, and propidium iodide-positive staining; enhanced the maturation and release of proinflammatory cytokine IL-1β and activation of the NLRP3 inflammasome; and markedly increased intracellular reactive oxygen species (ROS) and mitochondrial ROS (mtROS) levels. Moreover, NLRP3 siRNA transfection or treatment with inhibitors efficiently suppressed PA-induced pyroptosis, and pretreatment with total ROS scavenger or mtROS scavenger attenuated PA-induced NLRP3 inflammasome activation and subsequent pyroptosis. However, DHM pretreatment inhibited PA-induced pyroptotic cell death by increasing cell viability, decreasing LDH and IL-1β release, improving cell membrane integrity, and abolishing caspase-1 cleavage and subsequent IL-1β maturation. We also found that DHM pre-treatment remarkably reduced the levels of intracellular ROS and mtROS and activated the Nrf2 signaling pathway. Moreover, knockdown of Nrf2 by siRNA abrogated the inhibitory effects of DHM on ROS generation and subsequent PA-induced pyroptosis. Together, these results indicate that the Nrf2 signaling pathway plays a role, as least in part, in the DHM-mediated improvement in PA-induced pyroptosis in vascular endothelial cells, which implies the underlying medicinal value of DHM targeting immune/inflammatory-related diseases, such as atherosclerosis. © 2017 BioFactors, 44(2):123-136, 2018.

Alterations in System xc- Expression in the Retina of Type 1 Diabetic Rats and the Role of Nrf2

Nrf2 (nuclear factor erythroid 2-related factor 2), a transcription factor that controls expression of several proteins that are related to cellular antioxidant capacity, such as the subunit xCT of the system x_c^-, is dysregulated in diabetes. Recently, it was described that system x_c^- is decreased in the retina after 3 weeks of diabetes. So, in the present work, the temporal relationship between xCT and Nrf2 in the retina of diabetic animals was investigated. Diabetes was induced in male Wistar rats (200 g) by a single injection of streptozotocin, and retinas were collected after 1, 2, and 6 months of diabetes induction. Expression of xCT, Nrf2 activity, and binding to antioxidant-responsive element (ARE) sequence were evaluated. Glutathione and reactive oxygen species (ROS) levels were also assessed. After 1 month of diabetes, Nrf2 activity, xCT expression, and glutathione levels were reduced whereas ROS were increased. Although glutathione and ROS levels remain unchanged until later stages, Nrf2 activity and xCT expression returned to normal levels after 2 months. However, they were decreased again at 6 months of diabetes. Accordingly, Nrf2 binding to xCT ARE sequence followed the same pattern of Nrf2 activity and xCT expression. These data showed that retinal xCT expression is regulated by Nrf2 in diabetic condition. The results also demonstrated a temporal relationship between Nrf2 and system x_c^- which could be implicated in the initiation of oxidative stress in retina in diabetes.

Shifts in renin-angiotensin system components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa region of streptozotocin-induced diabetic mice

PURPOSE

This study aimed to analyse shifts in renin-angiotensin system (RAS) components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa (LC) region in streptozotocin (STZ)-induced diabetic mice.

METHODS

Six months after diabetes induction, the retinal vessels of male C57BL/6 J mice were observed by colour photography, fundus fluorescein angiography (FFA), and immunofluorescent staining following incubation with CD31. Immunofluorescence for glial fibrillary acidic protein (GFAP), alpha-smooth muscle actin (α-SMA),and NG2 was also performed. Angiotensin-converting enzyme 1 (ACE1), angiotensin II type I receptor (AT1R), renin, hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), and haeme oxygenase 1 (HO-1) expression levels were confirmed by immunohistochemical and western blotting analyses.

RESULTS

Compared with control mice, diabetic mice had significantly higher blood glucose concentrations (p < 0.001) and significantly lower body weights (p < 0.001). Colour photography and FFA did not reveal any vessel abnormalities in the diabetic mice; however, immunostaining of whole-mount retinas revealed an increased number of retinal vessels. Furthermore, histopathological staining showed significant reduction in the whole retinal thickness. GFAP expression was slightly higher, whereas fewer NG2⁺ pericytes were observed in diabetic mice than in control mice. ACE1, AT1R, renin, HIF-1α, VEGF, VEGFR2, and HO-1 expression were up-regulated in the LC of the STZ-induced diabetic mice.

CONCLUSIONS

Collectively, ACE 1, AT1R, HIF-1α, VEGF, VEGFR2, and HO-1 activation in the LC region in diabetic mice may be involved in diabetes via the RAS and induction of angiogenesis and oxidative stress.

Deletion of the Neurotrophin Receptor p75NTR Prevents Diabetes-Induced Retinal Acellular Capillaries in Streptozotocin-Induced Mouse Diabetic Model

Diabetic retinopathy is characterized by early stage of retinal neuro-inflammation that triggers development of acellular capillaries and a late stage of pathological neovascularization. Due to limited treatment options, there is a pressing need to develop new therapeutics. Our group discovered that diabetes-impaired processing of the nerve growth factor precursor (proNGF) resulting in its accumulation and its receptor p75^NTR. Here, we examine the protective effects of modulating p75^NTR in experimental model of diabetic retinopathy. Diabetes was induced using streptozotocin in both wild type (WT) and p75^NTR knockout (p75KO) mice. Retinal inflammation and microvascular dysfunction were assessed. Western blot analysis was performed to assess expression of apoptotic and inflammatory markers and levels of the neurotrophin, p75^NTR and ephrin-B2. Deletion of p75^NTR did not alter body weight or diabetes status compared to WT mice. In WT-mice, diabetes triggered retinal inflammation, significant decrease in pericyte count and marked increase in development of occluded (acellular) capillary formation after 24-weeks. Deletion of p75^NTR prevented acellular capillary, restored pericyte count, and inhibited the retinal Ephrin-B2, activation of the stress-kinase JNK and apoptotic marker cleaved caspase-3 in the diabetic retina. Deletion of p75^NTR reduced retinal inflammation, and proNGF expression. These effects coincided with increased NGF level and TrkA activation in the diabetic retina. Targeting p75^NTR using genetic approach protected the retina from the impact of long-term diabetes in mediating microvascular degeneration and maintains the balance of NGF/proNGF level. Together, these results provide rationale that targeting p75^NTR may offer novel and effective therapeutic strategy to combat diabetic retinopathy.

Protective Effect of Prunus Cerasus (Sour Cherry) Seed Extract on the Recovery of Ischemia/Reperfusion-Induced Retinal Damage in Zucker Diabetic Fatty Rat

Among diabetes patients, ophthalmological complications are very frequent. High blood glucose and (consequential) ischemia-reperfusion (I/R) injury contribute significantly to the severity of retinopathies. Diabetic retinopathy is among the leading causes of blindness. Our study demonstrates the effect of sour cherry seed extract (SCSE) on blood glucose and function of the retina with electroretinography (ERG) in a diabetic setting with or without ischemia-reperfusion (I/R) injury in Zucker Diabetic Fatty (ZDF) rats. Our results prove that the SCSE has a retinoprotective effect in diabetic rats: according to ERG measurements, SCSE treatment mitigated the retinal function-damaging effect of diabetes, and proved to be protective in the diabetic eye against ischemia-reperfusion injuries of the retina. Outcomes suggest that the protective effects of SCSE may occur through several pathways, including HO-1 dependent mechanisms. The observation that SCSE treatment decreases blood glucose is also novel. These findings offer the possibility for development of novel therapeutic strategies utilizing this emerging functional food, in particular in the prevention of conditions resulting from high blood glucose or I/R injury, such as deterioration of retinal microcirculation.

Kaempferide Protects against Myocardial Ischemia/Reperfusion Injury through Activation of the PI3K/Akt/GSK-3β Pathway

The aim of this study is to investigate both the efficacy and mechanism of action of kaempferide (Kae) as a therapy for the treatment of cardiovascular disease. A rat model of myocardial ischemia/reperfusion (I/R) injury was established by ligation of the left anterior descending coronary artery for 30 min followed by a 2 h perfusion. In our study, we show that Kae remarkably improved cardiac function, alleviated myocardial injury via a decrease in myocardial enzyme levels, and attenuated myocardial infarct size in a dose-dependent manner. In addition, preconditioning treatment with Kae was found to significantly decrease serum TNF-α, IL-6, C-reactive protein (CRP), MDA, and ROS levels, while it was found to increase serum levels of SOD. Nuclear factor erythroid 2-related factor 2 (Nrf2) and cleaved caspase-3 expression levels were observed to be downregulated, while phospho-Akt (p-Akt) and phospho-glycogen synthase kinase-3β (p-GSK-3β) expression levels were upregulated. However, cotreatment with LY294002 (a PI3K inhibitor) or TDZD-8 (a GSK-3β inhibitor) was found to abolish the above cardioprotective effects observed with the Kae treatment. The data presented in this study provides evidence that Kae attenuates I/R-induced myocardial injury through inhibition of the Nrf2 and cleaved caspase-3 signaling pathways via a PI3K/Akt/GSK 3β-dependent mechanism.

Phenolic compounds isolated from fermented blueberry juice decrease hepatocellular glucose output and enhance muscle glucose uptake in cultured murine and human cells

Background

We recently reported that blueberry juice fermented (FJ) with Serratia vaccinii bacterium has antidiabetic activities both in vivo and in vitro. The purpose of this project was to elucidate the effect of FJ on glucose homeostasis in liver and skeletal muscle cells and to identify active fractions/compounds responsible for this effect.

Methods

FJ was fractionated using standard chromatography procedures. Hepatic (H4IIE, HepG2) and skeletal muscle cells (C2C12) were treated with maximum non-toxic concentrations of FJ, fractions and isolated compounds thereof. Glucose-6-phosphatase (G6Pase) activity was measured using glucose oxidase method. To measure glucose uptake and glycogen synthase (GS) activity, radioactive assays were used.

Results

Fractionation of FJ yielded seven fractions. FJ and its phenolic fractions F2, F3-1 and F3-2 respectively inhibited G-6Pase by 31, 45, 51 and 26%; activated GS by 2.3-, 2.3-, 2.2- and 2-fold; and stimulated glucose uptake by 19, 25, 18 and 15%, as compared to DMSO vehicle control. Subfractionation of the active fractions yielded 4 compounds (catechol, chlorogenic, gallic and protocatechuic acid). Catechol, yielding the greatest bioactivity in G6Pase and glucose uptake assays, decreased G6Pase activity by 54%, increased GS by 2-fold and stimulated glucose uptake by 44% at 45.5 μM.

Conclusions

This study identifies novel potential antidiabetic compounds that can help standardize FJ.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1650-2) contains supplementary material, which is available to authorized users.

The Combination of Blueberry Juice and Probiotics Ameliorate Non-Alcoholic Steatohepatitis (NASH) by Affecting SREBP-1c/PNPLA-3 Pathway via PPAR-α

Nonalcoholic steatohepatitis (NASH) is liver inflammation and a major threat to public health. Several pharmaceutical agents have been used for NASH therapy but their high-rate side effects limit the use. Blueberry juice and probiotics (BP) have anti-inflammation and antibacterial properties, and may be potential candidates for NASH therapy. To understand the molecular mechanism, Sprague Dawley rats were used to create NASH models and received different treatments. Liver tissues were examined using HE (hematoxylin and eosin) and ORO (Oil Red O) stain, and serum biochemical indices were measured. The levels of peroxisome proliferators-activated receptor (PPAR)-α, sterol regulatory element binding protein-1c (SREBP-1c), Patatin-like phospholipase domain-containing protein 3 (PNPLA-3), inflammatory cytokines and apoptosis biomarkers in liver tissues were measured by qRT-PCR and Western blot. HE and ORO analysis indicated that the hepatocytes were seriously damaged with more and larger lipid droplets in NASH models while BP reduced the number and size of lipid droplets (p < 0.05). Meanwhile, BP increased the levels of SOD (superoxide dismutase), GSH (reduced glutathione) and HDL-C (high-density lipoprotein cholesterol), and reduced the levels of AST (aspartate aminotransferase), ALT (alanine aminotransferase), TG (triglycerides), LDL-C (low-density lipoprotein cholesterol) and MDA (malondialdehyde) in NASH models (p < 0.05). BP increased the level of PPAR-α (Peroxisome proliferator-activated receptor α), and reduced the levels of SREBP-1c (sterol regulatory element binding protein-1c) and PNPLA-3 (Patatin-like phospholipase domain-containing protein 3) (p < 0.05). BP reduced hepatic inflammation and apoptosis by affecting IL-6 (interleukin 6), TNF-α (Tumor necrosis factor α), caspase-3 and Bcl-2 in NASH models. Furthermore, PPAR-α inhibitor increased the level of SREBP-1c and PNPLA-3. Therefore, BP prevents NASH progression by affecting SREBP-1c/PNPLA-3 pathway via PPAR-α.