Inhibition of proteasome activity by anthocyanins and anthocyanidins

Computational exploration of FOXM1 inhibitors for glioblastoma: an integrated virtual screening and molecular dynamics simulation study

In this study, a comprehensive investigation of a set of phytochemicals to identify potential inhibitors for the Forkhead box protein M1 (FOXM1) was conducted. FOXM1 is overexpressed in glioblastoma (GBM) cells and plays a crucial role in cell cycle progression, proliferation, and invasion. FOXM1 inhibitors have shown promising results in preclinical studies, and ongoing clinical trials are assessing their efficacy in GBM patients. However, there are limited studies on the identification of novel compounds against this attractive therapeutic target. To address this, the NPACT database containing 1,574 phytochemicals was used, employing a hierarchical multistep docking approach, followed by an estimation of relative binding free energy. By fixing user-defined XP-dock and MM-GBSA cut-off scores of -6.096 and -37.881 kcal/mol, the chemical space was further narrowed. Through exhaustive analysis of molecular binding interactions and various pharmacokinetics profiles, we identified four compounds, namely NPACT00002, NPACT01454, NPACT00856, and NPACT01417, as potential FOXM1 inhibitors. To assess the stability of protein-ligand binding in dynamic conditions, 100 ns Molecular dynamics (MD) simulations studies were performed. Furthermore, Molecular mechanics with generalized Born and surface area solvation (MM-GBSA) based binding free energy estimations of the entire simulation trajectories revealed a strong binding affinity of all identified compounds towards FOXM1, surpassing that of the control drug Troglitazone. Based on extensively studied multistep docking approaches, we propose that these molecules hold promise as FOXM1 inhibitors for potential therapeutic applications in GBM. However, experimental validation will be necessary to confirm their efficacy as targeted therapies.Communicated by Ramaswamy H. Sarma.

New Scaffolds of Proteasome Inhibitors: Boosting Anticancer Potential by Exploiting the Synergy of In Silico and In Vitro Methodologies

Cancer is a complex multifactorial disease whose pathophysiology involves multiple metabolic pathways, including the ubiquitin-proteasome system, for which several proteasome inhibitors have already been approved for clinical use. However, the resistance to existing therapies and the occurrence of severe adverse effects is still a concern. The purpose of this study was the discovery of novel scaffolds of proteasome inhibitors with anticancer activity, aiming to overcome the limitations of the existing proteasome inhibitors. Thus, a structure-based virtual screening protocol was developed using the structure of the human 20S proteasome, and 246 compounds from virtual databases were selected for in vitro evaluation, namely proteasome inhibition assays and cell viability assays. Compound 4 (JHG58) was shortlisted as the best hit compound based on its potential in terms of proteasome inhibitory activity and its ability to induce cell death (both with IC50 values in the low micromolar range). Molecular docking studies revealed that compound 4 interacts with key residues, namely with the catalytic Thr1, Ala20, Thr21, Lys33, and Asp125 at the chymotrypsin-like catalytic active site. The hit compound is a good candidate for additional optimization through a hit-to-lead campaign.

Neuroprotective mechanisms of red clover and soy isoflavones in Parkinson's disease models

Parkinson's disease (PD) is a neurodegenerative disorder characterized by nigrostriatal degeneration and the spreading of aggregated forms of the presynaptic protein α-synuclein (aSyn) throughout the brain. PD patients are currently only treated with symptomatic therapies, and strategies to slow or stop the progressive neurodegeneration underlying the disease's motor and cognitive symptoms are greatly needed. The time between the first neurobiochemical alterations and the initial presentation of symptoms is thought to span several years, and early neuroprotective dietary interventions could delay the disease onset or slow PD progression. In this study, we characterized the neuroprotective effects of isoflavones, a class of dietary polyphenols found in soy products and in the medicinal plant red clover (Trifolium pratense). We found that isoflavone-rich extracts and individual isoflavones rescued the loss of dopaminergic neurons and the shortening of neurites in primary mesencephalic cultures exposed to two PD-related insults, the environmental toxin rotenone and an adenovirus encoding the A53T aSyn mutant. The extracts and individual isoflavones also activated the Nrf2-mediated antioxidant response in astrocytes via a mechanism involving inhibition of the ubiquitin-proteasome system, and they alleviated deficits in mitochondrial respiration. Furthermore, an isoflavone-enriched soy extract reduced motor dysfunction exhibited by rats lesioned with the PD-related neurotoxin 6-OHDA. These findings suggest that plant-derived isoflavones could serve as dietary supplements to delay PD onset in at-risk individuals and mitigate neurodegeneration in the brains of patients.

Anti-Multiple Myeloma Potential of Secondary Metabolites from Hibiscus sabdariffa-Part 2

Multiple Myeloma (MM) is an aggressive tumor causing millions of deaths every year and currently available therapies are often unsuccessful or correlated with severe side effects. In our previous work we demonstrated that the Hibiscus sabdariffa hydroalcoholic extract inhibits the growth of the MM cell line and we isolated two metabolites responsible for the activity: Hib-ester and Hib-carbaldehyde. Herein we report their interaction with proteasome, one of the main targets in the fight against MM. The molecular modelling study outlined a good interaction of both compounds with the target and these results prompted us to investigate their potential to inhibit proteasome. Metabolites were then isolated from the calyces and an extract with a high content of Hib-ester and Hib-carbaldehyde was prepared. An anticancer profile was drawn, evaluating apoptosis, autophagy and proteasome inhibition, with the anticancer properties being mainly attributed to the Hib-ester and Hib-carbaldehyde, while the proteasome inhibition of the extract could also be ascribed to the presence of anthocyanins, a class of secondary metabolites already known for their proteasome inhibitory activity.

Review of Functional and Pharmacological Activities of Berries

Functional plant-based foods (such as fruits, vegetables, and berries) can improve health, have a preventive effect, and diminish the risk of different chronic diseases during in vivo and in vitro studies. Berries contain many phytochemicals, fibers, vitamins, and minerals. The primary phytochemicals in berry fruits are phenolic compounds including flavonoids (anthocyanins, flavonols, flavones, flavanols, flavanones, and isoflavonoids), tannins, and phenolic acids. Since berries have a high concentration of polyphenols, it is possible to use them for treating various diseases pharmacologically by acting on oxidative stress and inflammation, which are often the leading causes of diabetes, neurological, cardiovascular diseases, and cancer. This review examines commonly consumed berries: blackberries, blackcurrants, blueberries, cranberries, raspberries, black raspberries, and strawberries and their polyphenols as potential medicinal foods (due to the presence of pharmacologically active compounds) in the treatment of diabetes, cardiovascular problems, and other diseases. Moreover, much attention is paid to the bioavailability of active berry components. Hence, this comprehensive review shows that berries and their bioactive compounds possess medicinal properties and have therapeutic potential. Nevertheless, future clinical trials are required to study and improve the bioavailability of berries' phenolic compounds and extend the evidence that the active compounds of berries can be used as medicinal foods against various diseases.

A NOVEL NOX/PHOX-CD38-NAADP-TFEB AXIS IMPORTANT FOR MACROPHAGE ACTIVATION DURING BACTERIAL PHAGOCYTOSIS

Macrophage activation in the presence of bacterial cells and molecules entails complex programs of gene expression. How such triggers elicit specific gene expression programs is incompletely understood. We previously discovered that TFEB (transcription factor EB) is a key contributor to macrophage activation during bacterial phagocytosis. However, the mechanism linking phagocytosis of bacterial cells to TFEB activation and downstream pro-inflammatory cytokine induction remained unknown. We found that macrophages lacking both TFEB and TFE3 (transcription factor E3) were unable to mount a pro-inflammatory phenotype in response to bacterial infection. The NOX/PHOX (NADPH oxidase)-dependent oxidative burst was required for nuclear translocation of TFEB during phagocytosis of Gram-positive or -negative bacteria, and reactive oxygen species (ROS) were sufficient to trigger TFEB activation in a CD38- and NAADP (nicotinic acid adenine dinucleotide phosphate)-dependent manner. Consistent with the Ca²⁺-releasing activity of NAADP, intracellular Ca²⁺ chelation and PPP3/calcineurin inhibition prevented TFEB activation by phagocytosis and ROS (reactive oxygen species), impairing the induction of pro-inflammatory cytokines such as IL6 and TNF/TNFα. Therefore, here we describe a previously unknown pathway that links phagocytosis with macrophage pro-inflammatory polarization via TFEB and related transcription factor TFE3. These findings reveal that activation of TFEB and TFE3 is a key regulatory event for the activation of macrophages, and have important implications for infections, inflammation, cancer, obesity, and atherosclerosis.

Jaceosidin Ameliorates Insulin Resistance and Kidney Dysfunction by Enhancing Insulin Receptor Signaling and the Antioxidant Defense System in Type 2 Diabetic Mice

Emerging evidence has shown that flavonoids extracted from Artemisia have beneficial effects on metabolic disorders. However, whether and how jaceosidin ameliorates insulin resistance and diabetic nephropathy in type 2 diabetes mellitus is largely unknown. For 8 weeks, db/db diabetic mice were fed with or without jaceosidin. Oral jaceosidin supplementation reduced fasting blood glucose levels and insulin resistance through the upregulation of insulin receptor downstream pathways in the liver and skeletal muscles. While jaceosidin did not noticeably alter kidney filtration function, this dietary intervention contributed to attenuating the accumulation of advanced glycation end products in diabetic kidneys. The levels of VEGF-a (vascular endothelial growth factor-a) proteins in the diabetic kidneys were markedly diminished by jaceosidin treatments, which increased the expression and activity of Cu (copper) and Zn-SOD (zinc-superoxide dismutase). Therefore, it is suggested that jaceosidin supplementation elicits antidiabetic effects and treats diabetic nephropathy by augmenting insulin signaling, suppressing fibrosis, and enhancing antioxidant activity.

Bioactive Compounds and Their Effect on Blood Pressure-A Review

Elevated blood pressure affects a great part of the elderly population and is the leading risk factor for cardiovascular disease. New approaches have been taken in the fight against this growing problem, in the form of diets (Mediterranean, Dietary Approaches to Stop Hypertension (DASH) and intermittent fasting). Recent research has shown the promising results regarding diets and their effect on the prevention and improvement of elevated blood pressure. This review attempts to take this a step further, reviewing 26 studies in the search for dietary elements that may be causing this improvement. Although good evidence was found in favor of lycopene, Docosahexaenoic acid (DHA), fiber and anthocyanin, further evidence is needed before any conclusions can be made. In contrast, the evidence shows that licorice increases blood pressure.

Ginkgo Biloba Extract in Ophthalmic and Systemic Disease, With a Focus on Normal-Tension Glaucoma

Glaucoma is a neurodegenerative eye disease that results in retinal ganglion cell loss and ultimately loss of vision. Elevated intraocular pressure (IOP) is the most common known risk factor for retinal ganglion cell damage and visual field loss, and the only modifiable risk factor proven to reduce the development and progression of glaucoma. This has greatly influenced our approach and assessment in terms of diagnosis and treatment. However, as many as ≥50% of patients with progressive vision loss from primary open angle glaucoma without IOP elevation (≤22 mm Hg) have been reported in the United States and Canada; 90% in Japan and 80% in Korea. Extensive research is currently underway to identify the etiology of risk factors for glaucoma other than or in addition to elevated IOP (so-called "normal-tension" glaucoma; NTG) and use this knowledge to expand available treatment options. Currently, Food and Drug Administration-approved medications for glaucoma exclusively target elevated IOP, suggesting the need for additional approaches to treatment options beyond the current scope as the definition of glaucoma changes to encompass cellular and molecular mechanisms. This review focuses on alternative medical approaches, specifically Ginkgo Biloba extract, as a potential treatment option for normal-tension glaucoma.

Targeting Ubiquitin-Proteasome Pathway by Natural Products: Novel Therapeutic Strategy for Treatment of Neurodegenerative Diseases

Misfolded proteins are the main common feature of neurodegenerative diseases, thereby, normal proteostasis is an important mechanism to regulate the neural survival and the central nervous system functionality. The ubiquitin-proteasome system (UPS) is a non-lysosomal proteolytic pathway involved in numerous normal functions of the nervous system, modulation of neurotransmitter release, synaptic plasticity, and recycling of membrane receptors or degradation of damaged and regulatory intracellular proteins. Aberrant accumulation of intracellular ubiquitin-positive inclusions has been implicated to a variety of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington disease (HD), Amyotrophic Lateral Sclerosis (ALS), and Multiple Myeloma (MM). Genetic mutation in deubiquitinating enzyme could disrupt UPS and results in destructive effects on neuron survival. To date, various agents were characterized with proteasome-inhibitory potential. Proteins of the ubiquitin-proteasome system, and in particular, E3 ubiquitin ligases, may be promising molecular targets for neurodegenerative drug discovery. Phytochemicals, specifically polyphenols (PPs), were reported to act as proteasome-inhibitors or may modulate the proteasome activity. PPs modify the UPS by means of accumulation of ubiquitinated proteins, suppression of neuronal apoptosis, reduction of neurotoxicity, and improvement of synaptic plasticity and transmission. This is the first comprehensive review on the effect of PPs on UPS. Here, we review the recent findings describing various aspects of UPS dysregulation in neurodegenerative disorders. This review attempts to summarize the latest reports on the neuroprotective properties involved in the proper functioning of natural polyphenolic compounds with implication for targeting ubiquitin-proteasome pathway in the neurodegenerative diseases. We highlight the evidence suggesting that polyphenolic compounds have a dose and disorder dependent effects in improving neurological dysfunctions, and so their mechanism of action could stimulate the UPS, induce the protein degradation or inhibit UPS and reduce protein degradation. Future studies should focus on molecular mechanisms by which PPs can interfere this complex regulatory system at specific stages of the disease development and progression.

Cognitive Function and Consumption of Fruit and Vegetable Polyphenols in a Young Population: Is There a Relationship?

Scientific evidence has shown the relationship between consumption of fruits and vegetables and their polyphenols with the prevention or treatment of diseases. The aim of this review was to find out whether the same relationship exists between fruits and vegetables and cognitive function, especially memory, in a young population. The mechanisms by which polyphenols of fruits and vegetables can exert cognitive benefits were also evaluated. These compounds act to improve neuronal plasticity through the protein CREB (Camp Response Element Binding) in the hippocampus, modulating pathways of signaling and transcription factors (ERK/Akt). In the same way, brain-derived neurotrophic factor (BDNF) is implicated in the maintenance, survival, growth, and differentiation of neurons. All these effects are produced by an increase of cerebral blood flow and an increase of the blood’s nitric oxide levels and oxygenation.

Consumption of an Anthocyanin-Rich Extract Made From New Zealand Blackcurrants Prior to Exercise May Assist Recovery From Oxidative Stress and Maintains Circulating Neutrophil Function: A Pilot Study

Aim: To evaluate blackcurrant anthocyanin-rich extract (BAE) consumption on time- and dose-dependent plasma anthocyanin bioavailability and conduct a pilot study to explore the potential effect of BAE in promoting recovery from exercise-induced oxidative stress, and maintenance of circulating neutrophil function.

Methods: Time- and dose-dependent blackcurrant anthocyanin bioavailability was assessed using LC-MS in 12 participants over 6 h after the ingestion of a placebo or BAE containing 0.8, 1.6, or 3.2 mg/kg total anthocyanins. In a separate pilot intervention exercise trial, 32 participants consumed either a placebo or 0.8, 1.6, or 3.2 mg/kg BAE (8 individuals per group), and then 1 h later performed a 30 min row at 70% VO₂max. Blood was collected during the trial for oxidative, antioxidant, inflammatory, and circulating neutrophil status.

Results: Consumption of BAE caused a time- and dose-dependent increase in plasma anthocyanins, peaking at 2 h after ingestion of 3.2 mg/kg BAE (217 ± 69 nM). BAE consumed 1 h prior to a 30 min row had no effect on plasma antioxidant status but hastened the recovery from exercise-induced oxidative stress: By 2 h recovery, consumption of 1.6 mg/kg BAE prior to exercise caused a significant (P < 0.05) 34 and 32% decrease in post-exercise plasma oxidative capacity and protein carbonyl levels, respectively, compared to placebo. BAE consumption prior to exercise dose-dependently attenuated a small, yet significant (P < 0.01) transient 13 ± 2% decline in circulating neutrophils observed in the placebo group immediately post-exercise. Furthermore, the timed consumption of either 1.6 or 3.2 mg/kg BAE attenuated a 17 ± 2.4% (P < 0.05) decline in neutrophil phagocytic capability of opsonised FITC-Escherichia coli observed 6 h post-exercise in the placebo group. Similarly, a dose-dependent increase in neutrophil surface expression of complement receptor-3 complex (CR3, critical for effective phagocytosis of opsonised microbes), was observed 6 h post-exercise in both 1.6 and 3.2 mg/kg BAE intervention groups.

Conclusions: Consumption of BAE (>1.6 mg/kg) 1 h prior to exercise facilitated recovery from exercise-induced oxidative stress and preserved circulating neutrophil function. This study provides data to underpin a larger study designed to evaluate the efficacy of timed BAE consumption on post-exercise recovery and innate immunity.

Anthocyanins in the Management of Metabolic Syndrome: A Pharmacological and Biopharmaceutical Review

The term "metabolic syndrome" (MetS) refers to a combination of diabetes, high blood pressure, and obesity. The origin of MetS includes a combination of multiple factors, such as sedentary lifestyle, unhealthy diet choice, and genetic factors. MetS is highly prevalent and adversely affects the general population by elevating risk of cardiovascular complications, organ failure, and much other pathology associated with late-stage diabetes. Anthocyanins (ANTs) are health-promoting bioactive compounds belonging to the flavonoids subclass of polyphenols. Numerous studies have reported the potential therapeutic benefits on MetS syndrome and diabetes from fruits rich in ANTs. This review summarizes the role of several dietary ANTs on preventing and managing MetS as well as the pharmacological mechanisms and biopharmaceutical features of their action. We also discuss potential nanoformulation and encapsulation approaches that may enhance the bioefficacy of ANTs in MetS. Experiments have demonstrated that ANTs may attenuate the symptoms of MetS via improving insulin resistance, impaired glucose tolerance, dyslipidaemia, cholesterol levels, hypertension, blood glucose, protecting β cells, and preventing free radical production. In brief, the intake of ANT-rich supplements should be considered due to their plausible ability for prevention and management of MetS. Additionally, randomized double-blind clinical trials are obligatory for evaluating the bioefficacy and pharmacological mechanisms of ANTs and their pharmaceutical formulations in patients with MetS.

Pelargonidin improves memory deficit in amyloid β25-35 rat model of Alzheimer's disease by inhibition of glial activation, cholinesterase, and oxidative stress

Alzheimer's disease (AD) is a multifactorial disorder with devastating outcomes and few mostly palliative available therapeutic strategies. Pelargonidin (Pel), an anthocyanin compound, is an estrogen receptor agonist with lower side effects versus estrogen. This study examined neuroprotective effect of Pel on intrahippocampal amyloid β25-35 (Aβ) rat model of AD. Rats were divided into groups of sham, Aβ, and Pel-pretreated Aβ (10mg/kg; p.o.). Animals underwent Morris water maze (MWM) test in addition to measurement of hippocampal oxidative stress, acetylcholinesterase (AChE) activity, glial fibrillary acidic protein (GFAP) and inducible nitric oxide synthase (iNOS). Pel pretreatment of Aβ group significantly improved escape latency and distance swum in MWM versus Aβ group and attenuated hippocampal malondialdehyde (MDA) and increased catalase activity with no significant change of nitrite. Meanwhile, Pel improved hippocampal AChE activity and lowered GFAP level with no significant change of iNOS. Our results suggest that Pel could improve Aβ25-35-induced memory deficit through mitigation of oxidative stress, cholinergic dysfunction, and astrocyte reaction.

Dietary anthocyanins as a complementary medicinal approach for management of inflammatory bowel disease

Inflammatory bowel disease (IBD) is thought to result from a chronic or relapsing activation of the immune system in the GI tract. A growing body of evidence confirms the health benefits of dietary anthocyanins as plant-derived natural agents. The aim of this review is to provide an overview of several natural products rich in anthocyanins used worldwide for the treatment of IBD. Anthocyanins possess both protective and therapeutic functions in the management of IBD by alleviating oxidative stress processes, cytoprotective functions, downregulation of inflammatory cytokines and suppressing cellular signaling pathways of inflammatory processes. In conclusion, the consumption of anthocyanin-rich natural formulations must be promoted on the basis of their possible function in the prevention and treatment of gastrointestinal inflammatory disorders.

Pistachio supplementation attenuates motor and cognition impairments induced by cisplatin or vincristine in rats

Background:

A large number of natural products and dietary components have been evaluated as potential chemoprotective agents. In the present investigation we report the effects of treatment with the dietary antioxidant, pistachio, on cisplatin- or vincristine-induced neurotoxicity in male Wistar rats.

Materials and Methods:

Dietary pistachio (10%) was assessed for its neuroprotective effects through the alteration in performance of hippocampus- and cerebellum-related behaviors following chronic cisplatin (5 mg/kg) or vincristine (0.2 mg/kg) treatment in male rats. We also evaluated the effects of cisplatin, vincristine, and pistachio administration on nociception. Six behavioral tasks were used: open field, rotarod, grasping, Morris water maze (MWM), hot plate, and motor nerve conductive velocity (MNCV).

Results:

We showed that the exposure of adolescent rats to cisplatin or vincristine resulted in a significant decrease in explorative behaviors and memory retention. Pistachio consumption somewhat improved memory and motor abilities in cisplatin- or vincristine-treated rats, while pistachio alone did not show any significant changes in these abilities compared to saline. Cisplatin and vincristine increased the latency of response to nociception, and pistachio did not reverse this effect.

Conclusion:

We conclude that pistachio in the diet following anticancer drugs such as cisplatin and vincristine might have a protective effect against anticancer drug-induced disruptions in motor and cognitive function. However, further studies are needed to elucidate the exact mechanisms of this protective effect of pistachio.

Determination of Anthocyanins and Total Polyphenols in a Variety of Elderberry Juices by UPLC-MS/MS and Other Methods

Elderberry (Sambucus spp.) juice contains a variety of polyphenols, mostly anthocyanins. In order to understand the variation of polyphenol levels by genotype, various elderberry juice samples were analyzed for total phenolics (TP), total monomeric anthocyanins (TMA) and individual anthocyanin content. The Folin-Ciocalteu total phenolic method and pH differential method were used to measure the TP and TMA content, respectively. The TP and TMA concentrations of elderberry were found to vary greatly among different genotypes. TMA content varied from 2.1% for 'Sperandio' to 60.6% for the 'Bob Gordon' cultivar. In addition, ultra-performance liquid chromatography with triple quadrupole mass spectrometry was used to separate and detect individual anthocyanins from samples prepared by solid phase extraction. Multiple-reaction-monitoring was used to process data for the reduction of false positives, maximizing selectivity, and reliable quantification. The quantitative performance of the method was validated, and a detection limit of 0.3 ng·ml^-1 for cyanidin 3-O-glucoside was determined. This newly developed method may serve to characterize and profile various anthocyanins in elderberry juices for quality control, assessment of dietary intake, and anthocyanin-based biomedical studies.

Antineoplastic activity of strawberry (Fragaria×ananassa Duch.) crude extracts on B16-F10 melanoma cells

The antiproliferative and differentiation potential of anthocyanin-rich strawberry fruit crude extracts (SE) were investigated on B16-F10 murine melanoma cells. Treatment of melanoma cells with SE produced a remarkable reduction of cell proliferation, paralleled with both the lowering of the intracellular levels of polyamine, and the enhancement of tissue transglutaminase (TG2, EC 2.3.2.13) activity (used as a differentiation marker). To gain further insight into profiling altered protein expression as a potential biomarker of the SE action on melanoma cells, analysis of the proteomic profile was performed on the treated B16-F10 cells, compared to the control. Following SE treatment, 30 proteins resulted up-regulated, and 87 proteins were down-regulated. In particular proteins overexpressed in cancer cells, involved in tumor progression and metabolism, were down-regulated. The possibility that SE may affect the Warburg effect in B16-F10 melanoma cells is discussed.

Synthesis and pharmacology of proteasome inhibitors

Shortly after the discovery of the proteasome it was proposed that inhibitors could stabilize proteins which ultimately would trigger apoptosis in tumor cells. The essential questions were whether small molecules would be able to inhibit the proteasome without generating prohibitive side effects and how one would derive these compounds. Fortunately, "Mother Nature" has generated a wide variety of natural products that provide distinct selectivities and specificities. The chemical synthesis of these natural products finally provided access to analogues and optimized drugs of which two different classes have been approved for the treatment of malignancies. Despite these achievements, additional lead structures derived from nature are under investigation and will be discussed with regard to their biological potential and chemical challenges.

Molecular mechanisms of the cardiovascular protective effects of polyphenols

Epidemiological studies have reported a greater reduction in cardiovascular risk and metabolic disorders associated with diets rich in polyphenols. The antioxidant effects of polyphenols are attributed to the regulation of redox enzymes by reducing reactive oxygen species production from mitochondria, NADPH oxidases and uncoupled endothelial NO synthase in addition to also up-regulating multiple antioxidant enzymes. Although data supporting the effects of polyphenols in reducing oxidative stress are promising, several studies have suggested additional mechanisms in the health benefits of polyphenols. Polyphenols from red wine increase endothelial NO production leading to endothelium-dependent relaxation in conditions such as hypertension, stroke or the metabolic syndrome. Numerous molecules contained in fruits and vegetables can activate sirtuins to increase lifespan and silence metabolic and physiological disturbances associated with endothelial NO dysfunction. Although intracellular pathways involved in the endothelial effects of polyphenols are partially described, the molecular targets of these polyphenols are not completely elucidated. We review the novel aspects of polyphenols on several targets that could trigger the health benefits of polyphenols in conditions such as metabolic and cardiovascular disturbances.

Direct effects of Vaccinium myrtillus L. fruit extracts on rat heart mitochondrial functions

In this study, the direct influence of bilberry (Vaccinium myrtillus) fruit extracts (aqueous and ethanolic) rich in anthocyanins on the oxidative phosphorylation of isolated rat heart mitochondria was investigated in vitro. Higher concentrations of bilberry extracts concentration-dependently inhibited mitochondrial state 3 respiration (by 23%-61%) with pyruvate plus malate, mildly (by 1.2- to 1.3-fold) uncoupled the oxidative phosphorylation, and increased (by 30%-87%) the state 4 respiration rate in the presence of exogenous cytochrome c. Succinate oxidation was less affected. Pure anthocyanins, the main components of used extracts, malvidin-3-glucoside, malvidin-3-galactoside, and cyanidin-3-galactoside, had no effect on oxidation of pyruvate plus malate. A statistically significant decrease in H2 O2 production by mitochondria was found in the presence of bilberry fruit extracts. Our findings show that bilberry fruit anthocyanin-rich extracts possess direct effects on rat heart mitochondrial function in vitro. These findings give the first insights into the mechanism(s) of their action on cellular energy metabolism.

Proteasome inhibitor up regulates liver antioxidative enzymes in rat model of alcoholic liver disease

Oxidative stress occurs in the liver of rats fed with alcohol chronically due to ethanol metabolism by CYP2E1, causing liver injury. The proteasome is considered as an antioxidant defense in the cell because of its activity in removing damaged and oxidized proteins, but a growing body of evidence shows that proteasome inhibitor treatment, at a non toxic low dose, provides protection against oxidative stress. In the present study, rats were fed with ethanol for 4 weeks and were treated with the proteasome inhibitor PS-341 (Bortezomib, Velcade®). Exposure to proteasome inhibitor elicited the elevation of antioxidative defense by enhancing the levels of mRNA and protein expression transcripts of glutathione reductase (GSR), glutathione synthetase (GSS), glutathione peroxidase 2 (GPX2), and superoxide dismutase 2 (SOD2) in the liver of rats fed with ethanol chronically, while ethanol alone did not increase these genes' mRNA. Our results also showed that glutamate cysteine ligase catalytic subunit (GCLC), a rate-limiting enzyme in glutathione biosynthesis, was also up regulated in the liver of rats fed with ethanol and injected with PS-431. Nrf2 mRNA level was significantly decreased in the liver of ethanol fed rats, as well as in the livers of animal fed with ethanol and treated with proteasome inhibitor, indicating that the mechanism by which proteasome inhibitor up regulates the antioxidant response element is not due to regulation of Nrf2. However, ATF4, a major regulator of antioxidant response elements, was significantly up regulated by proteasome inhibitor treatment. The beneficial effects of proteasome inhibitor treatment also reside in the reversibility of the drug because the proteasome activity was significantly increased 72 h post treatment. In conclusion, proteasome inhibitor treatment used at a non toxic low dose has potential protective effects against oxidative stress due to chronic ethanol feeding.

Proteasome inhibitors: Dozens of molecules and still counting

The discovery of the proteasome in the late 80's as the core protease of what will be then called the ubiquitin-proteasome system, rapidly followed by the development of specific inhibitors of this enzyme, opened up a new era in biology in the 90's. Indeed, the first proteasome inhibitors were instrumental for understanding that the proteasome is a key actor in most, if not all, cellular processes. The recognition of the central role of this complex in intracellular proteolysis in turn fuelled an intense quest for novel compounds with both increased selectivity towards the proteasome and better bioavailability that could be used in fundamental research or in the clinic. To date, a plethora of molecules that target the proteasome have been identified or designed. The success of the proteasome inhibitor bortezomib (Velcade(®)) as a new drug for the treatment of Multiple Myeloma, and the ongoing clinical trials to evaluate the effect of several other proteasome inhibitors in various human pathologies, illustrate the interest for human health of these compounds.

Anthocyanins: are they beneficial in treating ethanol neurotoxicity?

Heavy alcohol exposure produces profound damage to the developing central nervous system (CNS) as well as the adult brain. Children with fetal alcohol spectrum disorders (FASD) have a variety of cognitive, behavioral, and neurological impairments. FASD currently represents the leading cause of mental retardation. Excessive alcohol consumption is associated with Wernicke-Korsakoff syndrome (WKS) and neurodegeneration in the adult brain. Although the cellular/molecular mechanism underlying ethanol's neurotoxicity has not been fully understood, it is generally believed that oxidative stress plays an important role. Identification of neuroprotective agents that can ameliorate ethanol neurotoxicity is an important step for developing preventive/therapeutic strategies. Targeting ethanol-induced oxidative stress using natural antioxidants is an attractive approach. Anthocyanins, a large subgroup of flavonoids present in many vegetables and fruits, are safe and potent antioxidants. They exhibit diverse potential health benefits including cardioprotection, anti-atherosclerotic activity, anti-cancer, anti-diabetic, and anti-inflammation properties. Anthocyanins can cross the blood-brain barrier and distribute in the CNS. Recent studies indicate that anthocyanins represent novel neuroprotective agents and may be beneficial in ameliorating ethanol neurotoxicity. In this review, we discuss the evidence and potential of anthocyanins in alleviating ethanol-induced damage to the CNS. Furthermore, we discuss possible underlying mechanisms as well as future research approaches necessary to establish the therapeutic role of anthocyanins.

C-glycosylanthocyanidins synthesized from C-glycosylflavones

Nine C-glycosyldeoxyanthocyanidins, 6-C-beta-glucopyranosyl-7-O-methylapigeninidin, 6-C-beta-glucopyranosyl-7-O-methylluteolinidin, 6-C-beta-(2''-O-beta-glucopyranosylglucopyranosyl)-7-O-methylapigeninidin, 6-C-beta-(2''-O-beta-glucopyranosylglucopyranosyl)-7,4'-di-O-methylapigeninidin, 8-C-beta-glucopyranosylapigeninidin, 8-C-beta-(2''-O-alpha-rhamnopyranosylglucopyranosyl)apigeninidin, 8-C-beta-(2''-O-alpha-(4'''-O-acetylrhamnopyranosyl)glucopyranosyl)apigeninidin, 6,8-di-C-beta-glucopyranosylapigeninidin (8), 6,8-di-C-beta-glucopyranosyl-4'-O-methylluteolinidin (9), have been synthesized from their respective C-glycosylflavones (yields between 14% and 32%) by the Clemmensen reduction reaction using zinc-amalgam. The various precursors (C-glycosylflavones) of the C-glycosylanthocyanidins were isolated from either flowers of Iris sibirica L., leaves of Hawthorn 'Crataegi Folium Cum Flore', or lemons and oranges. This is the first time C-glycosylanthocyanidins have been synthesized. The structures of all flavonoids including the flavone rotamers were elucidated by 2D NMR techniques and high-resolution electrospray MS. The distribution of the various structural forms of 8 and 9 are different at pH 1.1, 4.5, and 7.0, however, the two pigments undergoes similar structural transformations at the various pH values. Pigments 8 and 9 with C-C linkages between the sugar moieties and the aglycone, were found to be far more stable towards acid hydrolysis than pelargonidin 3-O-glucoside, which has the typical anthocyanidin C-O linkage between the sugar and aglycone. This stability may extend the present use of anthocyanins as nutraceuticals, pharmaceuticals or colorants.

Current developments on the inhibitory effects of berry polyphenols on digestive enzymes

The recent developments and evidence for the effect of polyphenol components of berries on digestive enzymes has been reviewed. Certain plant polyphenols can inhibit starch digestive enzymes in the gastrointestinal tract and modulate blood glucose control in vivo. Certain berry polyphenol components can inhibit protease activities at levels which could affect protein digestion in the gastrointestinal tract. In addition, other polyphenol components show potential for the inhibition of gastrointestinal lipase activity, which is a proven therapeutic target for the control of obesity through reduced fat digestion. Taking into account the potential synergies for inhibition of starch and lipid digestion by the spectrum of polyphenol components present within berry species, the inhibition of digestive enzymes by dietary polyphenols may be another important mechanism for the health benefits attributed to a diet rich in fruit and vegetables.