Long-term dietary quercetin enrichment as a cardioprotective countermeasure in mdx mice

Therapeutic and Nutraceutical Effects of Polyphenolics from Natural Sources

The prevalence of cardiovascular disease, oxidative stress-related complications, and chronic age-related illnesses is gradually increasing worldwide. Several causes include the ineffectiveness of medicinal treatment therapies, their toxicity, their inability to provide radical solutions in some diseases, and the necessity of multiple drug therapy in certain chronic diseases. It is therefore necessary for alternative treatment methods to be sought. In this review, polyphenols were identified and classified according to their chemical structure, and the sources of these polyphenol molecules are indicated. The cardioprotective, ROS scavenging, anti-aging, anticancer properties of polyphenolic compounds have been demonstrated by the results of many studies, and these natural antioxidant molecules are potential alternative therapeutic agents.

The roles of quercetin in diabetes mellitus and related metabolic disorders; special focus on the modulation of gut microbiota: A comprehensive review

Quercetin is a dietary flavonoid that can affect the balance between anti-oxidant defense system and oxidative stress. A number of studies showed the positive effects of quercetin on diabetes mellitus and related metabolic disorders through different pathways such as gut flora. However, findings are conflicting. In addition, it seems no studies have summarized all potential mechanisms of quercetin in diabetes mellitus, so far. Therefore, the aims of the present comprehensive review were to provide an overview on biological and biochemical characteristics of quercetin and investigate the effect of quercetin on diabetes mellitus and related metabolic disorders by focusing on its effects on the modulation of gut microbiota. For this purpose, findings of In vitro, animal studies, clinical trials, and review studies with the English language published until January 2021 were summarized. They were identified through electronic databases (PubMed, Scopus, and Cochrane Library) and Google Scholar. Findings showed that quercetin can be an effective component for improving glycemic status and other metabolic disorders related to diabetes mellitus based on In vitro and animal studies. However, environmental factors, food processing and using nanoformulations can affect its efficacy in human studies. Several potential mechanisms, including the modulation of gut flora are proposed for its actions. However, due to limited clinical trials and contradictory findings, more high-quality clinical trials are needed to make a decision on the efficacy of supplementation with quercetin as a complementary therapy for the management of diabetes mellitus, metabolic disorders, and modulating gut flora.

Quercetin: A Bioactive Compound Imparting Cardiovascular and Neuroprotective Benefits: Scope for Exploring Fresh Produce, Their Wastes, and By-Products

Quercetin, a bioactive secondary metabolite, holds incredible importance in terms of bioactivities, which has been proved by in vivo and in vitro studies. The treatment of cardiovascular and neurological diseases by quercetin has been extensively investigated over the past decade. Quercetin is present naturally in appreciable amounts in fresh produce (fruits and vegetables). However, today, corresponding to the growing population and global demand for fresh fruits and vegetables, a paradigm shift and focus is laid towards exploring industrial food wastes and/or byproducts as a new resource to obtain bioactive compounds such as quercetin. Based on the available research reports over the last decade, quercetin has been suggested as a reliable therapeutic candidate for either treating or alleviating health issues, mainly those of cardiovascular and neurological diseases. In the present review, we have summarized some of the critical findings and hypotheses of quercetin from the available databases foreseeing its future use as a potential therapeutic agent to treat cardiovascular and neurological diseases. It is anticipated that this review will be a potential reference material for future research activities to be undertaken on quercetin obtained from fresh produce as well as their respective processing wastes/byproducts that rely on the circular concept.

A Systematic Review on the Role of SIRT1 in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a muscular disease characterized by progressive muscle degeneration. Life expectancy is between 30 and 50 years, and death is correlated with cardiac or respiratory complications. Currently, there is no cure, so there is a great interest in new pharmacological targets. Sirtuin1 (SIRT1) seems to be a potential target for DMD. In muscle tissue, SIRT1 exerts anti-inflammatory and antioxidant effects. The aim of this study is to summarize all the findings of in vivo and in vitro literature studies about the potential role of SIRT1 in DMD. A systematic literature search was performed according to PRISMA guidelines. Twenty-three articles satisfied the eligibility criteria. It emerged that SIRT1 inhibition led to muscle fragility, while conversely its activation improved muscle function. Additionally, resveratrol, a SIRT1 activator, has brought beneficial effects to the skeletal, cardiac and respiratory muscles by exerting anti-inflammatory activity that leads to reduced myofiber wasting.

Exercise Preconditioning as a Cardioprotective Phenotype

Cardiovascular disease (CVD) is potentiated by risk factors including physical inactivity and remains a leading cause of morbidity and mortality. Although regular physical activity does not reverse atherosclerotic coronary disease, precursory exercise improves clinical outcomes in those experiencing life-threatening CVD events. Exercise preconditioning describes the cardioprotective phenotype whereby even a few exercise bouts confer short-term multifaceted protection against acute myocardial infarction. First described decades ago in animal investigations, cardioprotective mechanisms responsible for exercise preconditioning have been identified through reductionist preclinical studies, including the upregulation of endogenous antioxidant enzymes, improved calcium handling, and enhanced bioenergetic regulation during a supply-demand mismatch. Until recently, translation of this research was only inferred from clinically-directed animal models of exercise involving ischemia-reperfusion injury, and reinforced by the gene products of exercise preconditioning that are common to mammalian species. However, recent clinical investigations confirm that exercise preconditions the human heart. This discovery means that simply the initiation of a remedial exercise regimen in those with abnormal CVD risk factor profiles will provide immediate cardioprotective benefits and improved clinical outcomes following acute cardiac events. In conclusion, the prophylactic biochemical adaptations to aerobic exercise are complemented by the long-term adaptive benefits of vascular and architectural remodeling in those who adopt a physically active lifestyle.

Role of the Renin-Angiotensin-Aldosterone System in Dystrophin-Deficient Cardiomyopathy

Dystrophin-deficient cardiomyopathy (DDC) is currently the leading cause of death in patients with dystrophinopathies. Targeting myocardial fibrosis (MF) has become a major therapeutic goal in order to prevent the occurrence of DDC. We aimed to review and summarize the current evidence about the role of the renin-angiotensin-aldosterone system (RAAS) in the development and perpetuation of MF in DCC. We conducted a comprehensive search of peer-reviewed English literature on PubMed about this subject. We found increasing preclinical evidence from studies in animal models during the last 20 years pointing out a central role of RAAS in the development of MF in DDC. Local tissue RAAS acts directly mainly through its main fibrotic component angiotensin II (ANG2) and its transducer receptor (AT1R) and downstream TGF-b pathway. Additionally, it modulates the actions of most of the remaining pro-fibrotic factors involved in DDC. Despite limited clinical evidence, RAAS blockade constitutes the most studied, available and promising therapeutic strategy against MF and DDC. Conclusion: Based on the evidence reviewed, it would be recommendable to start RAAS blockade therapy through angiotensin converter enzyme inhibitors (ACEI) or AT1R blockers (ARBs) alone or in combination with mineralocorticoid receptor antagonists (MRa) at the youngest age after the diagnosis of dystrophinopathies, in order to delay the occurrence or slow the progression of MF, even before the detection of any cardiovascular alteration.

Nutraceutical and pharmaceutical cocktails did not preserve diaphragm muscle function or reduce muscle damage in D2-mdx mice

NEW FINDINGS

What is the central question of this study? We previously demonstrated that quercetin transiently preserved respiratory function in dystrophin-deficient mice. To gain lasting therapeutic benefits, we tested quercetin in combination with nicotinamide riboside, lisinopril and prednisolone in the D2-mdx model. What is the main finding and its importance? We demonstrated that these quercetin-based cocktails did not preserve respiratory or diaphragmatic function or reduce histological damage after 7 months of treatment starting at 4 months of age.

ABSTRACT

Duchenne muscular dystrophy is characterized by the absence of dystrophin protein and causes muscle weakness and muscle injury, culminating in respiratory failure and cardiomyopathy. Quercetin transiently improved respiratory function but failed to maintain long-term therapeutic benefits in mdx mice. In this study, we combined quercetin with nicotinamide riboside (NR), lisinopril and prednisolone to assess the efficacy of quercetin-based cocktails. We hypothesized that quercetin, NR and lisinopril independently would improve respiratory function and decrease diaphragmatic injury and when combined would have additive effects. To address this hypothesis, in vivo respiratory function, in vitro diaphragmatic function and histological injury were assessed in DBA (healthy), D2-mdx (dystrophic) and D2-mdx mice treated with combinations of quercetin, NR and lisinopril from 4 to 11 months of age. Respiratory function, assessed using whole-body plethysmography, was largely similar between healthy and dystrophin-deficient mice. Diaphragm specific tension was decreased by ∼50% in dystrophic mice compared with healthy mice (P < 0.05), but fatigue resistance was similar between groups. Contractile area was decreased by ∼10% (P < 0.05) and fibrotic area increased from 3.5% in healthy diaphragms to 27% (P < 0.05) in dystrophic diaphragms. Contrary to expectations, these functional and histological parameters of disease were not offset by any intervention. These data suggest that quercetin, NR and lisinopril, independently and in combination, did not prevent diaphragmatic injury or preserve respiratory function.

Autophagy in the heart is enhanced and independent of disease progression in mus musculus dystrophinopathy models

Background

Duchenne muscular dystrophy is a muscle wasting disease caused by dystrophin gene mutations resulting in dysfunctional dystrophin protein. Autophagy, a proteolytic process, is impaired in dystrophic skeletal muscle though little is known about the effect of dystrophin deficiency on autophagy in cardiac muscle. We hypothesized that with disease progression autophagy would become increasingly dysfunctional based upon indirect autophagic markers.

Methods

Markers of autophagy were measured by western blot in 7-week-old and 17-month-old control (C57) and dystrophic (mdx) hearts.

Results

Counter to our hypothesis, markers of autophagy were similar between groups. Given these surprising results, two independent experiments were conducted using 14-month-old mdx mice or 10-month-old mdx/Utrn^± mice, a more severe model of Duchenne muscular dystrophy. Data from these animals suggest increased autophagosome degradation.

Conclusion

Together these data suggest that autophagy is not impaired in the dystrophic myocardium as it is in dystrophic skeletal muscle and that disease progression and related injury is independent of autophagic dysfunction.

Nutraceutical and pharmaceutical cocktails did not improve muscle function or reduce histological damage in D2-mdx mice

Progressive muscle injury and weakness are hallmarks of Duchenne muscular dystrophy. We showed previously that quercetin (Q) partially protected dystrophic limb muscles from disease-related injury. As quercetin activates PGC-1α through Sirtuin-1, an NAD⁺-dependent deacetylase, the depleted NAD⁺ in dystrophic skeletal muscle may limit quercetin efficacy; hence, supplementation with the NAD⁺ donor, nicotinamide riboside (NR), may facilitate quercetin efficacy. Lisinopril (Lis) protects skeletal muscle and improves cardiac function in dystrophin-deficient mice; therefore, it was included in this study to evaluate the effects of lisinopril used with quercetin and NR. Our purpose was to determine the extent to which Q, NR, and Lis decreased dystrophic injury. We hypothesized that Q, NR, or Lis alone would improve muscle function and decrease histological injury and when used in combination would have additive effects. Muscle function of 11-mo-old DBA (healthy), D2-mdx (dystrophin-deficient), and D2-mdx mice was assessed after treatment with Q, NR, and/or Lis for 7 mo. To mimic typical pharmacology of patients with Duchenne muscular dystrophy, a group was treated with prednisolone (Pred) in combination with Q, NR, and Lis. At 11 mo of age, dystrophin deficiency decreased specific tension and tetanic force in the soleus and extensor digitorum longus muscles and was not corrected by any treatment. Dystrophic muscle was more sensitive to contraction-induced injury, which was partially offset in the QNRLisPred group, whereas fatigue was similar between all groups. Treatments did not decrease histological damage. These data suggest that treatment with Q, NR, Lis, and Pred failed to adequately maintain dystrophic limb muscle function or decrease histological damage.NEW & NOTEWORTHY Despite a compelling rationale and previous evidence to the contrary in short-term investigations, quercetin, nicotinamide riboside, or Lisinopril, alone or in combination, failed to restore muscle function or decrease histological injury in dystrophic limb muscle from D2-mdx mice after long-term administration. Importantly, we also found that in the D2-mdx model, an emerging and relatively understudied model of Duchenne muscular dystrophy dystrophin deficiency caused profound muscle dysfunction and histopathology in skeletal muscle.

An Innovative Approach to the Preparation of Plasma Samples for UHPLC-MS Analysis

A new sample processing method for analyzing flavonol metabolites in plasma using enzymatic proteolysis was developed and validated. Four endopeptidases were examined regarding their influence on the analyte recovery of quercetin-3- O-glucuronide (Q3GlcA). Methanol was added to inactivate and precipitate the enzymes, and samples were concentrated via evaporation prior to UHPLC-MS analysis. Quercetin-3- O-rutinoside (Q3Rut) was used as an internal standard. The selectivity and accuracy of the established UHPLC-ESI-MS ⁿ method showed a coefficient of variation (CV) of the repeatability of the measuring instrument of 1.7% for Q3GlcA. The average recovery of Q3GlcA was approximately 67% with an interday method precision of 24% and r = 46.9 as its repeatability. Therefore, enzymatic proteolysis has proven to be a suitable alternative to the methods previously described in the literature, such as solid-phase extraction (SPE). Still, the method has only been validated for Q3GlcA, but its applicability to other substance classes seems possible.

Combination of quercetin and Adriamycin effectively suppresses the growth of refractory acute leukemia

The present study aimed to investigate the effect of combined treatment with quercetin and Adriamycin (doxorubicin) on the development of refractory acute leukemia. Primary leukemic cells were isolated from patients with refractory drug-resistant acute leukemia. The Cell Counting Kit-8 assay was used to detect the proliferation of cells treated with a range of doses of Adriamycin, quercetin and a combination of the two drugs. Non-irradiated mice were used to establish a T cell acute lymphoblastic leukemia (T-ALL) model, which was subsequently treated with Adriamycin, quercetin and a combination of the two drugs. The survival time was recorded, and white and red blood cells and platelets in mouse peripheral blood were counted. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of cardiac tissues were measured as indicators of oxidative stress and damage. Proliferation of primary leukemic cells was reduced by Adriamycin depending on the dose (0.06, 0.6 or 6 µg/ml) and treatment duration (24, 48 or 72 h) compared with the vehicle treated group. Co-treatment with quercetin achieved a similar suppression of leukemic cell proliferation when a lower dose of Adriamycin (0.03, 0.3 or 3 µg/ml) was administered for the same duration. The survival of non-irradiated mice with T-ALL was improved by co-treatment with a high dose of Adriamycin and quercetin compared with either treatment alone. Compared with treatment with Adriamycin alone, the combined treatment with Adriamycin and quercetin significantly enhanced the SOD activity and reduced the MDA content in the heart. Therefore, quercetin may enhance the effects of Adriamycin on refractory acute leukemia.

Tempol Supplementation Restores Diaphragm Force and Metabolic Enzyme Activities in mdx Mice

Duchenne muscular dystrophy (DMD) is characterized by striated muscle weakness, cardiomyopathy, and respiratory failure. Since oxidative stress is recognized as a secondary pathology in DMD, the efficacy of antioxidant intervention, using the superoxide scavenger tempol, was examined on functional and biochemical status of dystrophin-deficient diaphragm muscle. Diaphragm muscle function was assessed, ex vivo, in adult male wild-type and dystrophin-deficient mdx mice, with and without a 14-day antioxidant intervention. The enzymatic activities of muscle citrate synthase, phosphofructokinase, and lactate dehydrogenase were assessed using spectrophotometric assays. Dystrophic diaphragm displayed mechanical dysfunction and altered biochemical status. Chronic tempol supplementation in the drinking water increased diaphragm functional capacity and citrate synthase and lactate dehydrogenase enzymatic activities, restoring all values to wild-type levels. Chronic supplementation with tempol recovers force-generating capacity and metabolic enzyme activity in mdx diaphragm. These findings may have relevance in the search for therapeutic strategies in neuromuscular disease.