Protective Effects of Blueberry Anthocyanins against H2O2-Induced Oxidative Injuries in Human Retinal Pigment Epithelial Cells

Ferulic acid (FA) protects human retinal pigment epithelial cells from H2 O2 -induced oxidative injuries

The aim of present study is to investigate whether Ferulic acid (FA), a natural polyphenol antioxidant, was able to protect ARPE-19 cells from hydrogen peroxide (H2 O2 )-induced damage, and elucidate the underlying mechanisms. Our results revealed that FA pre-treatment for 24 hours can reverse cell loss of H2 O2 -induced ARPE-19 cells via the promotion of cell proliferation and prevention of apoptosis, as evidenced by 5-ethynyl-2'-deoxyuridine (EdU) incorporation and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) assay, respectively. Moreover, the addition of FA (5 mM) can decrease Bax and cleaved caspase-3 protein expression, but increase Bcl-2 protein expression in ARPE-19 cells. Furthermore, H2 O2 -induced oxidative stress in ARPE-19 cells was significantly alleviated by FA, illustrated by reduced levels of ROS and MDA. In addition, the attenuated antioxidant enzymes activities of (SOD, CAT and GPX) and GSH level were reversed almost to the normal base level by the pre-addition of FA for 24 hours. In all assays, FA itself did not exert any effect on the change of the above parameters. These novel findings indicated that FA effectively protected human ARPE-19 cells from H2 O2 -induced oxidative damage through its pro-proliferation, anti-apoptosis and antioxidant activity, suggesting that FA has a therapeutic potential in the prevention and treatment of AMD.

Malvidin induces hepatic stellate cell apoptosis via the endoplasmic reticulum stress pathway and mitochondrial pathway

Blueberries have great beneficial effects due to high level of anthocyanins, especially malvidin. Hepatic stellate cells (HSCs) can be activated and increase excessive extracellular matrix (ECM) components, which play a central role in liver fibrogenesis. Therefore, activated HSC's apoptosis can be induced to recover liver fibrosis. Malvidin's effects on apoptosis in rat activated hepatic stellate T6 cells (HSC-T6) in vitro were investigated here. High concentration of malvidin was found to significantly induce apoptosis, activate caspase-3, increase malondialdehyde, upregulate Bax, but downregulate Bcl-2. Moreover, malvidin upregulated the protein levels of some endoplasmic reticulum stress (ERS)-typical markers, including caspase-12, glucose-regulated protein 78 (GRP78), and CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), suggesting that malvidin induced HSC apoptosis by the ERS apoptosis pathway as well as the mitochondrial-dependent pathway. These findings indicated that blueberry anthocyanins, especially malvidin, could induce activated hepatic stellate cell apoptosis and might act as one kind of functional food ingredient or a novel nutraceutical beneficial for liver health.

Cyanidin-3-O-glucoside Protects Lens Epithelial Cells against High Glucose-Induced Apoptosis and Prevents Cataract Formation via Suppressing NF-κB Activation and Cox-2 Expression

Diabetic cataract is one of the most important causes of blindness worldwide. Cyanidin-3-O-glucoside (C3G) is found to exert beneficial effects on many diabetic complications. However, its effect on diabetic cataract is not well known. Herein, we investigated the effect of C3G on high glucose-induced lens epithelial cell (SRA01/04) apoptosis and cataract formation as well as the involved mechanisms. We found C3G (20 μM) could preserve cell viability in SRA01/04 cells exposed to high glucose (100 μM). Meanwhile, C3G inhibited SRA01/04 cell apoptosis and regulated the Bcl-2/Bax ratio. Additionally, C3G suppressed NF-κB activation and subsequent cyclooxygenases-2 (Cox-2) expression, which are associated with the protection against apoptosis. Moreover, C3G attenuated lens opacity and protein aggregation in lens culture exposed to high glucose. In conclusion, C3G protected against high glucose-induced SRA01/04 cell apoptosis and cataract formation, which indicated the potential protection of anthocyanins on diabetic cataract.

Children's liking and wanting of foods vary over multiple bites/sips of consumption: A case study of foods containing wild blueberry powder in the amounts targeted to deliver bioactive phytonutrients for children

To encourage children to frequently consume wild blueberries as part of their dietary patterns, incorporating blueberry powder into specific foods may be an effective strategy. Thus, it is important to determine appropriate types of food products that both minimize food processing-induced loss of beneficial components of blueberries (e.g., anthocyanins) and satisfy at the same time both nutritional and sensory aspects. For clinical studies assessing the health benefits of blueberry-containing food samples, it would be important to ensure children consume the entire portion of the test samples. This study, therefore, aimed at determining how sensory acceptability (liking) and psychological reward (wanting) of wild blueberry-based foods vary over multiple steps of ad libitum consumption: appearance, first bite/sip, half bite/sip, and full consumption. Five different types of foods containing the targeted amount of wild blueberry powder were prepared for sensory testing (oatmeal bar, beverage, ice pop, gummy, and cookie), and the residual amounts of total anthocyanin and chlorogenic acid were measured to confirm levels targeted to deliver bioactive amounts of these phytochemicals. Results showed that while overall liking and desire to eat did not differ among the five samples at the appearance and first bite/sip steps, they differed significantly at the end of consumption. Although children liked and wanted to consume the cookies more when compared to beverages, ice pops, and/or gummies, total anthocyanin contents were lower in cookies and gummies than in wild blueberry powder, beverage, and ice pop samples. Notably, the oatmeal bars with significant amounts of total anthocyanin and chlorogenic acid did not significantly differ from the cookies with respect to overall liking, desire to eat, and the amount consumed. In conclusion, this study shows that sensory evaluation using multiple bites/sips of ad libitum food consumption, along with a measurement of beneficial compounds, is efficient in determining appropriate vehicles for clinical studies of wild blueberry-containing foods.

Antioxidative and Neuroprotective Effects of the Cytochalasans From Endophytes

Six 10-indolyl-cytochalasans, chaetoglobosin F (1), chaetoglobosin Fex (2), chaetoglobosin E (3), cytoglobosin A (4), penochalasin C (5), and isochaetoglobosin D (6), and 2 10-phenyl-cytochalasans, cytochalasin H (7) and 18-methoxycytochalasin J (8) were isolated from 2 plant endophytes, Chaetomiun globosum WQ and Phomopsis sp. IFB-E060, respectively. These cytochalasans were investigated with radical-scavenging activity assay and hydrogen peroxide (H2O2)/ N-methyl-4-phenylpyridinium iodide (MPP+)-induced pheochromocytoma cell line 12 (PC12) cell models, respectively. Results showed that 7 compounds had antioxidative effects except 5, with scavenging 2,2-diphenyl-1-picrylhydrazyl radical effect 1 = 6= 7 > 2> 4 = 3 > 8 and scavenging 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical effect 1 = 6 = 7 > 2 > 3 > 8 > 4. They could also inhibit H2O2/MPP+-induced damage in PC12 cells by increasing cell viability and decreasing lactate dehydrogenase release. Compounds 1, 6, and 7 exhibited the strongest antioxidative potencies, which are more potent than vitamin E. Additionally, antioxidative and neuroprotective effects of 1∼8 showed some structure–activity relationship. These findings would be useful for looking for cytochalasin-related new lead compounds or drugs to prevent and treat Parkinson’s disease.

Antioxidant Blueberry Anthocyanins Induce Vasodilation via PI3K/Akt Signaling Pathway in High-Glucose-Induced Human Umbilical Vein Endothelial Cells

Blueberries are rich in antioxidant anthocyanins. The hypotensive effects of blueberry anthocyanins in endothelial cells was investigated here. Pretreatment with blueberry anthocyanin extract, malvidin, malvidin-3-glucoside, and malvidin-3-galactoside significantly ameliorated high-glucose-induced damage by enhancing endogenous antioxidant superoxide dismutase (SOD) and heme oxygenase-1 (HO-1), lowering reactive oxygen species (ROS) generation and NADPH oxidase isoform 4 (NOX4) expression, and increasing the cell vitalities. They also effectively induced a vasodilatory effect by increasing the vasodilator nitric oxide (NO) and its promoters endothelial NO synthase (eNOS) and peroxisome proliferator-activated receptor-γ (PPARγ) levels as well as by decreasing the vasoconstrictor angiotensin-converting enzyme (ACE), xanthine oxidase-1 (XO-1), and low-density lipoprotein (LDL) levels. The activation of phosphoinositide 3-kinase (PI3K)/Akt signaling pathway and the breakdown of protein kinase C zeta (PKCζ) pathway were involved in the bioactivities. The results indicated blueberry anthocyanins protected endothelial function against high-glucose (HG) injury via antioxidant and vasodilatory mechanisms, which could be promising molecules as a hypotensive nutraceutical for diabetes patients.

Comparison on chemical compositions and antioxidant capacities of the green, oolong, and red tea from blueberry leaves

Blueberry leaves, by‐products of the blueberry industry, could be explored as source of functional foods, such as teas. Three different types of tea, including nonfermented green tea, semifermented oolong tea, and fully fermented red tea from blueberry leaves, were investigated on their chemical compositions and antioxidant capacities here. The contents of individual amino acids in three types varied, while the total amounts retained constant. A total of 167 volatiles were detected with alcohols, alkenes, and aldehydes as the dominant. More volatiles produced in the fermented teas. The total phenolic/flavonoid contents were highest in the green tea and decreased significantly in the oolong and red teas, correlating inversely with the fermentation degree. The highest levels of representative phenolics, that is, phenolic acids and flavonol glycosides, contributed to the strongest antioxidant capacity in the green tea. These indicated that blueberry leaves provided promising and prospective potential to develop new teas beneficial for health.

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.

Protective effects of delphinidin against H2O2-induced oxidative injuries in human retinal pigment epithelial cells

Age-related macular degeneration (AMD) is now one of the leading causes of blindness in the elderly population and oxidative stress-induced damage to retinal pigment epithelial (RPE) cells occurs as part of the pathogenesis of AMD. In the present study, we evaluated the protective effect of delphinidin (2-(3,4,5-trihydroxyphenyl) chromenylium-3,5,7-triol) against hydrogen peroxide (H₂O₂)-induced toxicity in human ARPE-19 cells and its molecular mechanism. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry demonstrated that pretreatment of ARPE-19 cells with delphinidin (25, 50, and 100 μg/ml) significantly increased cell viability and reduced the apoptosis from H₂O₂ (0.5 mM)-induced oxidative stress in a concentration-dependent manner, which was achieved by the inhibition of Bax, cytochrome c, and caspase-3 protein expression and enhancement of Bcl-2 protein. The same tendency was observed in ARPE-19 cells pre-treated with 15 mM of N-acetylcysteine (NAC) before the addition of H₂O₂. Furthermore, pre-incubation of ARPE-19 cells with delphinidin markedly inhibited the intracellular reactive oxygen species (ROS) generation and Nox1 protein expression induced by H₂O₂. Moreover, the decreased antioxidant enzymes activities of superoxide dismutase (SOD), catalase (CAT), and glutathione-peroxidase (GSH-PX) and elevated (MDA) level in H₂O₂-treated cells were reversed to the normal standard by the addition of delphinidin, which was regulated by increasing nuclear Nrf2 protein expression in ARPE-19 cells. Our results suggest that delphinidin effectively protects human ARPE-19 cells from H₂O₂-induced oxidative damage via anti-apoptotic and antioxidant effects.

Highly Acylated Anthocyanins from Purple Sweet Potato ( Ipomoea batatas L.) Alleviate Hyperuricemia and Kidney Inflammation in Hyperuricemic Mice: Possible Attenuation Effects on Allopurinol

Allopurinol is the first-line medication for hyperuricemia treatment. However, severe drug-related adverse effects have often been reported among patients who received allopurinol administration. This study is aimed at evaluating the possible attenuation effects of highly acylated anthocyanins from purple sweet potato (HAA-PSP) on hyperuricemia and kidney inflammation in hyperuricemic mice treated with allopurinol. In comparison with 5 mg kg^-1 allopurinol used alone, the combination of 25 mg kg^-1 HAA-PSP and 2.5 mg kg^-1 allopurinol could not only reduce serum uric acid level in hyperuricemic mice but also attenuate the kidney damage, as indicated by the level of serum biomarkers as well as histopathological examination. The inflammatory response was partially mitigated by inhibiting the protein expression of typical cytokines in the kidney. Our findings provide new evidence for the supplementary therapeutic potential of HAA-PSP with allopurinol on hyperuricemia and inflammation-related syndromes. Moreover, this study provides a theoretical basis for assessing the potential of anthocyanin-rich foods in health.

Whole blueberry protects pancreatic beta-cells in diet-induced obese mouse

Background

Blueberry is rich in bioactive substances and possesses powerful antioxidant potential, which can protect against oxidant-induced and inflammatory cell damage and cytotoxicity. The aim of this study was to determine how blueberry affects glucose metabolism and pancreatic β-cell proliferation in high fat diet (HFD)-induced obese mice.

Methods

Wild type male mice at age of 4 weeks received two different kinds of diets: high-fat diet (HFD) containing 60% fat or modified HFD supplemented with 4% (wt:wt) freeze-dried whole blueberry powder (HFD + B) for 14 weeks. A separate experiment was performed in mice fed with low-fat diet (LFD) containing 10% fat or modified LFD + B supplemented with 4% (wt:wt) freeze-dried whole blueberry powder. The metabolic parameters including blood glucose and insulin levels, glucose and insulin tolerances were measured.

Results

Blueberry-supplemented diet significantly increased insulin sensitivity and glucose tolerance in HFD + B mice compared to HFD mice. However, no difference was observed in blood glucose and insulin sensitivity between LFD + B and LFD mice. In addition, blueberry increased β-cell survival and prevented HFD-induced β-cell expansion. The most important finding was the observation of presence of small scattered islets in blueberry treated obese mice, which may reflect a potential role of blueberry in regenerating pancreatic β-cells.

Conclusions

Blueberry-supplemented diet can prevent obesity-induced insulin resistance by improving insulin sensitivity and protecting pancreatic β-cells. Blueberry supplementation has the potential to protect and improve health conditions for both type 1 and type 2 diabetes patients.

Electronic supplementary material

The online version of this article (10.1186/s12986-019-0363-6) contains supplementary material, which is available to authorized users.

Label-free detection of hydrogen peroxide-induced oxidative stress in human retinal pigment epithelium cells via laser tweezers Raman spectroscopy

Human retinal pigment epithelium cells under hydrogen peroxide-induced oxidative stress and a ligustrazine-based protective effect were investigated using laser tweezers Raman spectroscopy. Protein and lipid were significantly affected by oxidative damage, along with increased reactive oxygen species (ROS) level within cells. The effects of ligustrazine against the reaction of ROS with protein seemed to be able to inhibit such damages but were limited during the desamidization of amides, along with additional effect on nucleic acid base and DNA phosphoric acid skeleton. This work laid the basis for both understanding the molecular mechanisms of oxidative stress-induced injury and highlighting possible biomarkers in retinal diseases.

Protective effects of anthocyanin against apoptosis and oxidative stress induced by arsanilic acid in DF-1 cells

Anthocyanin is a natural plant pigment that acts as an antioxidant and scavenges free radicals. This study aimed to investigate the potential protective role of nightshade anthocyanin (NA), a natural flavonoid compound, against the arsanilic acid (ASA)-induced cell death of DF-1 cells. DF-1 cells were initially exposed to ASA, and then NA was applied to the treated cells. Cell viability, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and apoptosis were examined. Results showed that NA inhibited the ASA-induced decrease in cell viability, increase in ROS, and loss of MMP in DF-1 cells. Moreover, caspase-3 activation was inhibited by ASA supplementation and NA attenuated the ASA-induced increase in the percentage of apoptotic cells. In summary, our study suggested that NA can enhance ASA-induced cytotoxicity and apoptosis, thereby providing a basis for the molecular mechanisms of NA-mediated protection.

Characterization of Purified Red Cabbage Anthocyanins: Improvement in HPLC Separation and Protective Effect against H₂O₂-Induced Oxidative Stress in HepG2 Cells

In this study, the chemical profiles and antioxidant activities of red cabbage anthocyanin (RCA)-enriched extract are evaluated. The effects of column temperature on the HPLC resolution of the RCAs are studied. The HPLC resolutions became better as the column temperature increased from 20 °C⁻45 °C. An optimized HPLC condition was achieved at 45 °C and used for the quantification and qualification of the RCAs. The anthocyanins in the enriched powder are all derivatives of cyanidin (268 ± 2 μg/mg), mainly with 19% nonacylated, 51% monoacylated, and 31% diacylated structures with ferulic, sinapic, p-coumaric, and caffeic acids characterized by HPLC-MS. The RCA extracts markedly reduced intracellular oxidative stress production by H₂O₂ on HepG2 cells and consequently ameliorated cell apoptosis and improved viability. The analytical method and cellular antioxidant activity demonstration of the RCAs will greatly facilitate their functional applications.

Protection of Kaempferol on Oxidative Stress-Induced Retinal Pigment Epithelial Cell Damage

The protection of retinal pigment epithelium (RPE) injury plays an important role in the prevention of or in delaying the pathological progress of retinal degeneration diseases, like age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa. Oxidative stress has been identified as a major inducer of RPE injury, which eventually could lead to a loss of vision. Kaempferol is a natural flavonoid widely distributed in many edible plants, fruits, and traditional medicines and has been reported to have antioxidant, anti-inflammatory, anticancer, and antimicrobial activities. The present study demonstrates that the total antioxidant capacity of kaempferol is approximately two times stronger than that of lutein which is also a natural antioxidant that is widely used in the prevention or treatment of AMD. Our data indicates that kaempferol protects human RPE cells (ARPE-19) from hydrogen peroxide- (H₂O₂-) induced oxidative cell damage and apoptosis through the signaling pathways involving Bax/Bcl-2 and caspase-3 molecules proofed by real-time PCR and Western blot results. Kaempferol also inhibits the upregulated vascular endothelial growth factor (VEGF) mRNA expression levels induced by H₂O₂ in ARPE-19 cells and affects the oxidation and antioxidant imbalanced system in ARPE-19 cells treated by H₂O₂ through the regulations of both the activities of reactive oxygen species (ROS) and superoxide dismutase (SOD). Furthermore, our in vivo experimental results show that in sodium iodate-induced retinal degeneration rat model, kaempferol could protect sodium iodate-induced pathological changes of retina tissue and retinal cells apoptosis as well as the upregulated VEGF protein expression in RPE cells. In summary, these novel findings demonstrate that kaempferol could protect oxidative stressed-human RPE cell damage through its antioxidant activity and antiapoptosis function, suggesting that kaempferol has a potential role in the prevention and therapeutic treatment of AMD or other retinal diseases mediated by oxidative stress.

Anthocyanin Tissue Bioavailability in Animals: Possible Implications for Human Health. A Systematic Review

Anthocyanins (ACNs) are promising health-enhancing phenolic compounds. We focus on ACN animal tissue bioavailability to provide an evidentiary link between tissue ACNs and their associated health properties. We performed a systematic review of electronic libraries; 279 results were retrieved, and 13 publications met inclusion criteria. Extracted information included animal model employed, administration route, doses, analysis method, and ACN concentration values in tissues. Total ACN concentrations were detected in mice kidney (2.17 × 10⁵ pmol/g), liver (1.73 × 10⁵ pmol/g), heart (3.6 × 10³ pmol/g), and lung (1.16 × 10⁵ pmol/g); and in pig brain (6.08 × 10³ pmol/g). ACNs showed a predominance of parent ACNs in long-term experiments versus an ACN metabolite predominance in short-term experiments. ACNs detected in animal tissues, such as cyanidin-3-glucoside, suggest it may have an important role in human health. This information could be useful to determine proper ACN-intake biomarkers in biological samples in futures studies.

Molecular Mechanism and Health Role of Functional Ingredients in Blueberry for Chronic Disease in Human Beings

Functional ingredients in blueberry have the best health benefits. To obtain a better understanding of the health role of blueberry in chronic disease, we conducted systematic preventive strategies for functional ingredients in blueberry, based on comprehensive databases, especially PubMed, ISI Web of Science, and CNKI for the period 2008⁻2018. Blueberry is rich in flavonoids (mainly anthocyanidins), polyphenols (procyanidin), phenolic acids, pyruvic acid, chlorogenic acid, and others, which have anticancer, anti-obesity, prevent degenerative diseases, anti-inflammation, protective properties for vision and liver, prevent heart diseases, antidiabetes, improve brain function, protective lung properties, strong bones, enhance immunity, prevent cardiovascular diseases, and improve cognitive decline. The anthocyanins and polyphenols in blueberry are major functional ingredients for preventive chronic disease. These results support findings that blueberry may be one of the best functional fruits, and further reveals the mechanisms of anthocyanins and polyphenols in the health role of blueberry for chronic disease. This paper may be used as scientific evidence for developing functional foods, nutraceuticals, and novel drugs of blueberry for preventive chronic diseases.

Effect of Long-Term Xanthophyll and Anthocyanin Supplementation on Lutein and Zeaxanthin Serum Concentrations and Macular Pigment Optical Density in Postmenopausal Women

Xanthophylls (lutein, L; zeaxanthin, Z) and anthocyanins are often included in food supplements to improve ocular health. There are no dietary reference intakes for them. The aim was to assess the effects of L, Z and anthocyanin supplementation on short and long-term lutein status markers (serum concentration and macular pigment optical density (MPOD)). Seventy-two postmenopausal women were randomized into a parallel study of 8 months: Group A-anthocyanines (60 mg/day); Group X-xanthophylls (6 mg L + 2 mg Z/day); Group X+A-anthocyanines (60 mg/day) + xanthophylls (6 mg L + 2 mg Z/day). At the beginning of the study, 4 and 8 month serum L and Z concentrations were determined (HPLC), as well as L, Z and anthocyanine dietary intake and MPOD (heterochromic flicker photometry). Baseline concentrations of L (0.35 ± 0.19 μmol/L), Z (0.11 ± 0.05 μmol/L), L+Z/cholesterol/triglycerides (0.07 ± 0.04 μmol/mmol) increased in Group X (2.8- and 1.6-fold in L and Z concentrations) and in group XA (2- and 1.4-fold in L and Z concentrations). MPOD (baseline: 0.32 ± 0.13 du) was not modified in any of the groups at the end of the study. There were no differences in the dietary intake of L+Z and anthocyanin at any point in time in any group. Supplementation of L and Z at a dietary level provoked an increase in their serum concentration that was not modified by simultaneous supplementation with anthocyanins.

A Randomized, Placebo-Controlled Study on the Safety and Efficacy of Daily Ingestion of Green Tea (Camellia sinensis L.) cv. "Yabukita" and "Sunrouge" on Eyestrain and Blood Pressure in Healthy Adults

The green tea (Camellia sinensis L.) cultivar “Sunrouge” contains anthocyanins, catechins and flavonols. To determine whether ingesting green tea containing anthocyanins improves visual function and blood pressure (BP) in healthy adults, a randomized, double-blind, placebo-controlled study was performed. A total of 120 healthy subjects, aged between 20 and 60 years and with a systolic BP (SBP) value of ≤125 and <155 and a diastolic BP (DBP) value <95, or a DBP of ≤75 mmHg and <95 mmHg and a SBP <155 mmHg, were randomly assigned to one of three groups. For 12 weeks, the placebo group received barley extract without catechin; another group received “Sunrouge” extract containing 11.2 mg anthocyanin and 323.6 mg epigallocatechin-3-O-gallate (EGCG); and a third group received “Yabukita” extract containing 322.2 mg EGCG. Home BP, accommodation ability, visual analog scale questionnaires for eyestrain, and metabolic-associated markers were analyzed at weeks 0, 4, 8, and 12 of the intake period. The ingestion of “Sunrouge” tea significantly improved accommodation ability and eyestrain in subjects younger than 45 years and in subjects who operated visual display terminals every day. It also elevated BP. “Yabukita” tea ingestion significantly increased serum adiponectin levels. No adverse effects were observed. We conclude that long-term intake of “Sunrouge” tea containing anthocyanins and flavonols might improve visual function.

High Glucose-Mediated Tyrosine Nitration of PI3-Kinase: A Molecular Switch of Survival and Apoptosis in Endothelial Cells

Diabetes and hyperglycemia are associated with increased retinal oxidative and nitrative stress and vascular cell death. Paradoxically, high glucose stimulates expression of survival and angiogenic growth factors. Therefore, we examined the hypothesis that high glucose-mediated tyrosine nitration causes inhibition of the survival protein PI3-kinase, and in particular, its regulatory p85 subunit in retinal endothelial cell (EC) cultures. Retinal EC were cultured in high glucose (HG, 25 mM) for 3 days or peroxynitrite (PN, 100 µM) overnight in the presence or absence of a peroxynitrite decomposition catalyst (FeTPPs, 2.5 µM), or the selective nitration inhibitor epicatechin (100 µM). Apoptosis of ECs was assessed using TUNEL assay and caspase-3 activity. Immunoprecipitation and Western blot were used to assess protein expression and tyrosine nitration of p85 subunit and its interaction with the p110 subunit. HG or PN accelerated apoptosis of retinal ECs compared to normal glucose (NG, 5 mM) controls. HG- or PN-treated cells also showed significant increases in tyrosine nitration on the p85 subunit of PI3-kinase that inhibited its association with the catalytic p110 subunit and impaired PI3-kinase/Akt kinase activity. Decomposing peroxynitrite or blocking tyrosine nitration of p85 restored the activity of PI3-kinase, and prevented apoptosis and activation of p38 MAPK. Inhibiting p38 MAPK or overexpression of the constitutively activated Myr-Akt construct prevented HG- or peroxynitrite-mediated apoptosis. In conclusion, HG impairs pro-survival signals and causes accelerated EC apoptosis, at least in part via tyrosine nitration and inhibition of PI3-kinase. Inhibitors of nitration can be used in adjuvant therapy to delay diabetic retinopathy and microvascular complication.