Plant polyphenols Morin and Quercetin rescue nitric oxide production in diabetic mouse aorta through distinct pathways

Carob leaves: Phytochemistry, antioxidant properties, vasorelaxant effect and mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

Ceratonia siliqua L., is a species of significant nutritional and industrial interest with extensive traditional uses. This fabaceae is renowned for its medicinal properties, including the treatment of high blood pressure. Due to its chemical composition, carob exhibits several valuable therapeutic functions such as antioxidant, antidiarrheal, antidiabetic, and antibacterial actions.

AIM OF THE REVIEW

This study investigates the chemical composition of Ceratonia siliqua L. leaves aqueous extract (CsAE) and explores the vasorelaxant effect and its underlying mechanisms. Acute toxicity and antioxidant activity of CsAE were also examined.

METHODS

The phytochemical profile was elucidated using TLC and UHPLC-MS. The vasorelaxant effect and mechanisms were studied on thoracic aortic rings from normotensive rats, using various antagonists. Acute toxicity was assessed by orally administering the extract to mice. Antioxidant activity was evaluated using β-carotene bleaching and DPPH.

RESULTS

TLC analysis of CsAE reveals flavonoids and hydrolysable tannins. Gallic acid, myricitrin, quercitrin as well as galloylglucopyranoside derivatives were identified by UHPLC-MS. CsAE relaxed phenylephrine-precontracted aorta in a concentration-dependent manner. This response was reduced when the aorta was denuded or pretreated with L-NAME, hydroxocobalamin, ODQ, 4-AP, TEA, calmidazolium chloride, and thapsigargin. CsAE showed significant antioxidant activity with no observed toxicity in the experimental animals.

CONCLUSION

CsAE has a significant vasodilatory effect, mediated through the CaM/eNOS/sGC pathway, activation of Kca and Kv, and intracellular calcium mobilization into SERCA. It also exhibits strong antioxidant activity, with no observed toxicity in the experimental animals. These findings represent the first evidence of the vasorelaxant effect of Ceratonia siliqua L. leaves from Eastern Morocco.

Molecular Mechanisms of Plant Extracts in Protecting Aging Blood Vessels

Plant Extracts (PE) are natural substances extracted from plants, rich in various bioactive components. Exploring the molecular mechanisms and interactions involved in the vascular protective effects of PE is beneficial for the development of further strategies to protect aging blood vessels. For this review, the content was obtained from scientific databases such as PubMed, China National Knowledge Infrastructure (CNKI), and Google Scholar up to July 2024, using the search terms "Plant extracts", "oxidative stress", "vascular aging", "endothelial dysfunction", "ROS", and "inflammation". This review highlighted the effects of PE in protecting aging blood vessels. Through pathways such as scavenging reactive oxygen species, activating antioxidant signaling pathways, enhancing respiratory chain complex activity, inhibiting mitochondrial-reactive oxygen species generation, improving nitric oxide bioavailability, downregulating the secretion of inflammatory factors, and activating sirtuins 1 and Nrf2 signaling pathways, it can improve vascular structural and functional changes caused by age-related oxidative stress, mitochondrial dysfunction, and inflammation due to aging, thereby reducing the incidence of age-related cardiovascular diseases.

Mechanisms of Flavonoids and Their Derivatives in Endothelial Dysfunction Induced by Oxidative Stress in Diabetes

Diabetic complications pose a significant threat to life and have a negative impact on quality of life in individuals with diabetes. Among the various factors contributing to the development of these complications, endothelial dysfunction plays a key role. The main mechanism underlying endothelial dysfunction in diabetes is oxidative stress, which adversely affects the production and availability of nitric oxide (NO). Flavonoids, a group of phenolic compounds found in vegetables, fruits, and fungi, exhibit strong antioxidant and anti-inflammatory properties. Several studies have provided evidence to suggest that flavonoids have a protective effect on diabetic complications. This review focuses on the imbalance between reactive oxygen species and the antioxidant system, as well as the changes in endothelial factors in diabetes. Furthermore, we summarize the protective mechanisms of flavonoids and their derivatives on endothelial dysfunction in diabetes by alleviating oxidative stress and modulating other signaling pathways. Although several studies underline the positive influence of flavonoids and their derivatives on endothelial dysfunction induced by oxidative stress in diabetes, numerous aspects still require clarification, such as optimal consumption levels, bioavailability, and side effects. Consequently, further investigations are necessary to enhance our understanding of the therapeutic potential of flavonoids and their derivatives in the treatment of diabetic complications.

Polyphenols mediated attenuation of diabetes associated cardiovascular complications: A comprehensive review

Background

Diabetes mellitus is a common chronic metabolic disorder that is characterized by increased levels of glucose for prolonged periods of time. Incessant hyperglycemia leads to diabetic complications such as retinopathy, nephropathy, and neuropathy, and cardiovascular complications such as ischemic heart disease, peripheral vascular disease, diabetic cardiomyopathy, stroke, etc. There are many studies that suggest that various polyphenols affect glucose homeostasis and can help to attenuate the complications associated with diabetes.

Objective

This review focuses on the possible role of various dietary polyphenols in palliating diabetes-induced cardiovascular complications. This review also aims to give an overview of the interrelationship among ROS production (due to diabetes), inflammation, glycoxidative stress, and cardiovascular complications as well as the anti-hyperglycemic effects of dietary polyphenols.

Methods

Various scientific databases including Scopus, Web of Science, Google Scholar, PubMed, Science Direct, Springer Link, and Wiley Online Library were used for searching articles that complied with the inclusion and exclusion criteria.

Results

This review lists several polyphenols based on various pre-clinical and clinical studies that have anti-hyperglycemic potential as well as a protective function against cardiovascular complications.

Conclusion

Several pre-clinical and clinical studies suggest that various dietary polyphenols can be a promising intervention for the attenuation of diabetes-associated cardiovascular complications.

3D printing-based lateral flow visual assay utilizing the dual-excitation property of nitrogen-doped carbon dots for the ratiometric determination and chemometric discrimination of flavonoids

A ratiometric fluorescence sensor has been established based on dual-excitation carbon dots (D-CDs) for the detection of flavonoids (morin is chosen as the typical detecting model for flavonoids). D-CDs were prepared using microwave radiation with o-phenylenediamine and melamine and exhibit controllable dual-excitation behavior through the regulation of their concentration. Remarkably, the short-wavelength excitation of D-CDs can be quenched by morin owing to the inner filter effect, while the long-wavelength excitation remains insensitive, serving as the reference signal. This contributes to the successful design of an excitation-based ratiometric sensor. Based on the distinct and differentiated variation of excitation intensity, morin can be determined from 0.156 to 110 µM with a low detection limit of 0.156 µM. In addition, an intelligent and visually lateral flow sensing device is developed for the determination  of morin content in real samples with satisfying recoveries, which indicates the potential application for human health monitoring.

Maackiain Mimics Caloric Restriction through aak-2-Mediated Lipid Reduction in Caenorhabditis elegans

Obesity prevalence is becoming a serious global health and economic issue and is a major risk factor for concomitant diseases that worsen the quality and duration of life. Therefore, the urgency of the development of novel therapies is of a particular importance. A previous study of ours revealed that the natural pterocarpan, maackiain (MACK), significantly inhibits adipogenic differentiation in human adipocytes through a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent mechanism. Considering the observed anti-adipogenic potential of MACK, we aimed to further elucidate the molecular mechanisms that drive its biological activity in a Caenorhabditis elegans obesity model. Therefore, in the current study, the anti-obesogenic effect of MACK (25, 50, and 100 μM) was compared to orlistat (ORST, 12 μM) as a reference drug. Additionally, the hybrid combination between the ORST (12 μM) and MACK (100 μM) was assessed for suspected synergistic interaction. Mechanistically, the observed anti-obesogenic effect of MACK was mediated through the upregulation of the key metabolic regulators, namely, the nuclear hormone receptor 49 (nhr-49) that is a functional homologue of the mammalian PPARs and the AMP-activated protein kinase (aak-2/AMPK) in C. elegans. Collectively, our investigation indicates that MACK has the potential to limit lipid accumulation and control obesity that deserves future developments.

A comprehensive view on the quercetin impact on bladder cancer: Focusing on oxidative stress, cellular, and molecular mechanisms

Bladder cancer (BC) is known as a prevalent genitourinary malignancy and has a significant mortality rate worldwide. Despite recent therapeutic approaches, the recurrence rate is high, highlighting the need for a new strategy to reduce the BC cell progression. Quercetin, a flavonoid compound, demonstrated promising anticancer properties and could be used in the management of various malignancies such as BC. This comprehensive review summarized quercetin's cellular and molecular mechanisms underlying anticancer activities. The study's findings indicated that quercetin prevents the proliferation of the human BC cell line, promotes apoptosis of BIU-87 cells, reduces the expression of p-P70S6K, and induces apoptosis by p-AMPK. Moreover, quercetin restricts tumor growth through the AMPK/mTOR cascade and prevents colony formation of human BC cells by triggering DNA damage. Studying this review article will help researchers better understand quercetin's functional role in the prevention and treatment of BC.

Quercetin activates the Sestrin2/AMPK/SIRT1 axis to improve amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease with poor prognosis. The intricacies surrounding its pathophysiology could partly account for the lack of effective treatment for ALS. Sestrin2 has been reported to improve metabolic, cardiovascular and neurodegenerative diseases, and is involved in the direct and indirect activation of the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/silent information regulator 1 (SIRT1) axis. Quercetin, as a phytochemical, has considerable biological activities, such as anti-oxidation, anti-inflammation, anti-tumorigenicity, and neuroprotection. Interestingly, quercetin can activate the AMPK/SIRT1 signaling pathway to reduce endoplasmic reticulum stress, and alleviate apoptosis and inflammation. This report examines the molecular relationship between Sestrin2 and AMPK/SIRT1 axis, as well as the main biological functions and research progress of quercetin, together with the correlation between quercetin and Sestrin2/AMPK/SIRT1 axis in neurodegenerative diseases.

Targeting PI3K/AKT signaling pathway in obesity

Obesity is a disorder with an increasing prevalence, which impairs the life quality of patients and intensifies societal health care costs. The development of safe and innovative prevention strategies and therapeutic approaches is thus of great importance. The complex pathophysiology of obesity involves multiple signaling pathways that influence energy metabolism in different tissues. The phosphatidylinositol 3-kinases (PI3K)/protein kinase B (AKT) pathway is critical for the metabolic homeostasis and its function in insulin-sensitive tissues is described in the context of health, obesity and obesity-related complications. The PI3K family participates in the regulation of diverse physiological processes including but not limited to cell growth, survival, differentiation, autophagy, chemotaxis, and metabolism depending on the cellular context. AKT is downstream of PI3K in the insulin signaling pathway, and promotes multiple cellular processes by targeting a plethora of regulatory proteins that control glucose and lipid metabolism. Natural products are essential for prevention and treatment of many human diseases, including obesity. Anti-obesity natural compounds effect multiple pathophysiological mechanisms involved in obesity development. Numerous recent preclinical studies reveal the advances in using plant secondary metabolites to target the PI3K/AKT signaling pathway for obesity management. In this paper the druggability of PI3K as a target for compounds with anti-obesity potential is evaluated. Perspectives on the strategies and limitations for clinical implementation of obesity management using natural compounds modulating the PI3K/AKT pathway are suggested.

Morin post-treatment surpassed calpeptin in ameliorating 3-NP-induced cortical neurotoxicity via modulation of glutamate/calpain axis, Kidins220, and BDNF/TrkB/AKT/CREB trajectory

The neuroprotective capacity of morin hydrate (MH), a potent antioxidant flavonoid, and calpeptin (CP), a calpain inhibitor, was documented against different insults but not Huntington's disease (HD). Accordingly, we aim to assess the neuroprotective potential of MH and/or CP in a 3-nitropropionic acid (3-NP)-induced HD model. The 3-NP-treated rats were post-treated with saline, MH, CP, or MH + CP for a week. Post-treatment with MH and/or CP amended motor function (beam walking test) and short-/ long-term spatial memory (novel object recognition test) and improved cortical microscopic architecture. On the molecular level, MH, and to a lesser extent CP, inhibited the cortical content/expression of glutamate, calpain, and Kidins220 and abated the inflammatory molecules, nuclear factor (NF)-κB, tumor necrosis factor-α, and interleukin-1β, as well as lipid peroxidation. However, MH, but barely CP, activated the molecules of the neuroprotective trajectory; viz., brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase receptor B (TrkB), protein kinase B (AKT), and cAMP response element-binding protein (CREB). Compared to the single treatments, the combination regimen mediated further reductions in the cortical contents of glutamate, calpain, and Kidins220, effects that extended to entail the anti-inflammatory/anti-oxidant potentials of MH and to a greater extent CP. However, the combination of MH strengthened the fair effect of CP on the survival signaling pathway BDNF/TrkB/AKT/CREB. In conclusion, MH, CP, and especially their combination, afforded neuroprotection against HD through curbing the glutamate/calpain axis, Kidins220, as well as NF-κB-mediated neuroinflammation/oxidative stress, besides activating the BDNF/TrkB/AKT/CREB hub that was partly dependent on calpain inhibition.

Flavonoids as a therapeutical option for the treatment of thrombotic complications associated with COVID-19

The SARS-CoV-2 outbreak has been one of the largest public health crises globally, while thrombotic complications have emerged as an important factor contributing to mortality. Therefore, compounds that regulate the processes involved in thrombosis could represent a dietary strategy to prevent thrombotic complications involved in COVID-19. In August 2022, various databases were consulted using the keywords "flavonoids", "antiplatelet", "anticoagulant", "fibrinolytic", and "nitric oxide". Studies conducted between 2019 and 2022 were chosen. Flavonoids, at concentrations mainly between 2 and 300 μM, are capable of regulating platelet aggregation, blood coagulation, fibrinolysis, and nitric oxide production due to their action on multiple receptors and enzymes. Most of the studies have been carried out through in vitro and in silico models, and limited studies have reported the in vivo and clinical effect of flavonoids. Currently, quercetin has been the only flavonoid evaluated clinically in patients with COVID-19 for its effect on D-dimer levels. Therefore, clinical studies in COVID-19 patients analyzing the effect on platelet, coagulant, fibrinolytic, and nitric oxide parameters are required. In addition, further high-quality studies that consider cytotoxic safety and bioavailability are required to firmly propose flavonoids as a treatment for the thrombotic complications implicated in COVID-19.

Morin Augmented Myocardial eNOS/cGMP/PKG Signaling Pathway and Abated Oxidative and Inflammo-apoptotic Responses in Diethyl Phthalate and Bisphenol-S Co-Exposed Male Albino Rats

Cardiac failure accounts for many deaths worldwide. Increasing experimental evidence suggests that exposure to chemicals such as bisphenol-S (BPS) and diethyl phthalate (DEP) exacerbate cardiac injuries. Morin is a flavonoid with reported cardioprotective activity. This study evaluated the modulation of pathways relevant to cardiac endothelial function in rats exposed to BPS and DEP mixture (Mix). Thirty male albino rats were distributed across five groups (n = 6): control received dimethyl sulfoxide (DMSO) as vehicle, Mix dissolved in DMSO, Mix + morin (25 mg/kg), Mix + morin (50 mg/kg), and morin (50 mg/kg). After 21 days of oral exposure at 1 ml/kg bodyweight of the Mix and treatment with morin, the animals were sacrificed, and their hearts were excised for biochemical, histological, immunohistochemical, and gene expression analyses. Exposure to the Mix caused a significant increase in oxidative stress indices (H₂O₂, malondialdehyde, DNA fragmentation, and advanced oxidation protein products). Also, arginase, phosphodiesterase 5', and the relative expression of TNF-α, interleukin-1β, Bax, androgen receptor, and vascular endothelial growth factor were markedly increased. In contrast, nitric oxide, reduced glutathione, interleukin-10 levels, superoxide dismutase, catalase, and glutathione peroxidase activities decreased significantly. Furthermore, p-NF-kB-p65 expression increased markedly in the Mix-exposed group. Morin treatment significantly reversed these perturbations in a dose-dependent manner in most instances. This study concludes that morin might offer a cardioprotective effect by enhancing the cardiac endothelial system and attenuating oxidative stress, inflammation, and apoptosis elicited by BPS and DEP co-exposure in male Wistar rats.

Urinary Nitric Oxide Levels Are Associated with Blood Pressure, Fruit and Vegetable Intake and Total Polyphenol Excretion in Adolescents from the SI! Program

Nitric oxide (NO) is important to cardiovascular health (CVH), and its bioavailability could be regulated by the antioxidant effect of polyphenols, improving endothelial function and consequently blood pressure (BP). However, scant research has been carried out on NO and CVH correlates in adolescent populations. Therefore, our aim was to investigate the association between NO and the CVH status and other health factors in adolescents. NO, total polyphenol excretion (TPE), anthropometric measurements, BP, blood lipid profile, blood glucose, diet, physical activity, and smoking status were recorded, while CVH score was classified as ideal, intermediate, and poor. Negative associations were observed between NO and body mass index, body fat percentage, BP, and triglycerides; and positive associations between NO and skeletal muscle percentage, HDL-cholesterol, fruit and vegetable intake, and TPE was observed. To capture more complex interactions among different factors, multiple linear regression was performed, obtaining a significant association between NO and fruit and vegetable intake (β = 0.175), TPE (β = 0.225), and systolic BP (β = -0.235). We conclude that urinary NO levels are positively associated with the consumption of fruits and vegetables rich in antioxidants such as polyphenols and negatively associated with systolic BP.

Potential Role of Quercetin in Polycystic Ovary Syndrome and Its Complications: A Review

Polycystic ovary syndrome (PCOS) is a common multisystem disease with reproductive, metabolic and psychological abnormalities. It is characterized by a high prevalence rate in women of childbearing age and highly heterogeneous clinical manifestations, which seriously harm women’s physical and mental health. Quercetin (QUR) is a natural compound of flavonoids found in a variety of foods and medicinal plants. It can intervene with the pathologic process of PCOS from multiple targets and channels and has few adverse reactions. It is mentioned in this review that QUR can improve ovulation disorder, relieve Insulin resistance (IR), reduce androgen, regulate lipid metabolism, regulate gut microbiota and improve vascular endothelial function, which is of great significance in the treatment of PCOS.

The Role of Polyphenol in Modulating Associated Genes in Diabetes-Induced Vascular Disorders

Diabetes-induced vascular disorder is considered one of the deadly risk factors among diabetic patients that are caused by persistent hyperglycemia that eventually leads to cardiovascular diseases. Elevated reactive oxygen species (ROS) due to high blood glucose levels activate signaling pathways such as AGE/RAGE, PKC, polyol, and hexosamine pathways. The activated signaling pathway triggers oxidative stress, inflammation, and apoptosis which later lead to vascular dysfunction induced by diabetes. Polyphenol is a bioactive compound that can be found abundantly in plants such as vegetables, fruits, whole grains, and nuts. This compound exerts therapeutic effects in alleviating diabetes-induced vascular disorder, mainly due to its potential as an anti-oxidative, anti-inflammatory, and anti-apoptotic agent. In this review, we sought to summarize the recent discovery of polyphenol treatments in modulating associated genes involved in the progression of diabetes-induced vascular disorder.

White Wine—Induced Endothelium-Dependent Vasorelaxation in Sprague-Dawley Rats

The vasodilatory activity and polyphenolic content of commercially available white wine is low compared to red wines. This study assessed the vasodilator potential of white wines produced by four different fermentation processes: (1) white wine produced by the standard procedure; (2) grapes left to macerate completely for 30 days; (3) grapes left to macerate up to half of unfermented sugar; and (4) wine produced by cooling the must. All tested wine samples were analyzed for their phenolic content, antioxidant capacity, and ethanol content. Vasodilation was examined in the norepinephrine pre-contracted isolated rat aortas of male Sprague-Dawley rats randomly exposed to cumulative concentrations (0.1‰ to 8‰ final dilutions in organ baths) of each of the tested wine samples with or without quercetin and/or gallic acid supplementation, in the absence/presence of NOS inhibitor L-NAME. Standard procedure and the procedure involving must cooling gives wine with lower phenolic content, antioxidant capacity, and lower vasodilator potential, respectively. L-NAME inhibited vasodilation to all wine samples. Quercetin with or without gallic acid supplementation restored vasodilation. Results show that vasodilation to white wine is NO-dependent and suggest the possibility of increasing the antioxidant capacity and vasodilatory potential of white wine using different production procedures, depending on quercetin content.

Traditional Knowledge to Contemporary Medication in the Treatment of Infectious Disease Dengue: A Review

Dengue has become a worldwide affliction despite incessant efforts to search for a cure for this long-lived disease. Optimistic consequences for dengue vaccine are implausible as the efficiency is tied to previous dengue virus (DENV) exposure and a very high cost is required for large-scale production of vaccine. Medicinal plants are idyllic substitutes to fight DENV infection since they constitute important components of traditional medicine and show antiviral properties, although the mechanism behind the action of bioactive compounds to obstruct viral replication is less explored and yet to be discovered. This review includes the existing traditional knowledge on how DENV infects and multiplies in the host cells, conscripting different medicinal plants that obtained bioactive compounds with anti-dengue properties, and the probable mechanism on how bioactive compounds modulate the host immune system during DENV infection. Moreover, different plant species having such bioactive compounds reported for anti-DENV efficiency should be validated scientifically via different in vitro and in vivo studies.

Positive Lusitropic Effect of Quercetin on Isolated Ventricular Myocardia from Normal and Streptozotocin-Induced Diabetic Mice

The lusitropic effect of quercetin was examined on isolated ventricular myocardial tissue preparations from normal and streptozotocin-induced diabetic mice. The time required for 90% relaxation of the myocardium, which was prolonged in the diabetic mice, was shortened by quercetin in both normal and diabetic myocardia. This effect of quercetin was completely inhibited by cyclopiazonic acid but not by SEA0400. These results indicated that quercetin accelerates myocardial relaxation through activation of the sarco-endoplasmic reticulum Ca²⁺-ATPase.

Potential Vasculoprotective Effects of Blackcurrant (Ribes nigrum) Extract in Diabetic KK-Ay Mice

Polyphenols are bioactive compounds found naturally in fruits and vegetables; they are widely used in disease prevention and health maintenance. Polyphenol-rich blackcurrant extract (BCE) exerts beneficial effects on vascular health in menopausal model animals. However, the vasculoprotective effects in diabetes mellitus (DM) and atherosclerotic vascular disease secondary to DM are unknown. Therefore, we investigated whether BCE is effective in preventing atherosclerosis using KK-A^y mice as a diabetes model. The mice were divided into three groups and fed a high-fat diet supplemented with 1% BCE (BCE1), 3% BCE (BCE2), or Control for 9 weeks. The mice in the BCE2 group showed a considerable reduction in the disturbance of elastic lamina, foam cell formation, and vascular remodeling compared to those in the BCE1 and Control groups. Immunohistochemical staining indicated that the score of endothelial nitric oxide synthase staining intensity was significantly higher in both BCE2 (2.9) and BCE1 (1.9) compared to that in the Control (1.1). Furthermore, the score for the percentage of alpha-smooth muscle actin was significantly lower in the BCE2 (2.9%) than in the Control (2.1%). Our results suggest that the intake of anthocyanin-rich BCE could have beneficial effects on the blood vessels of diabetic patients.

Carbon dots for ratiometric fluorescence detection of morin

The B,N dual-doped carbon dots (B,N-CDs) for ratiometric fluorescence detection the morin were prepared from sodium tetraborate and polyethyleneimine through the single-step hydrothermal method. The B,N-CDs exhibited the optimum excitation and emission wavelength at 340 nm and 467 nm, respectively. Interestingly, the intensities of emission peak at 467 nm of B,N-CDs reduced meanwhile a new peak emerged at 560 nm with the continuous addition of morin, which revealed the ratio fluorescence characteristic between F_560nm/F_467nm and morin concentration with the linearity range and detection limit of 14.5-32.5 μmol/L and 0.3 μmol/L (S/N = 3), respectively. The interference of common antibiotics and remedies could be ignored when the concentration of morin was detected by the B,N-CDs, which demonstrating the outstanding selectivity. Furthermore, the proposed fluorescence method is used to detect morin in urine with recoveries are 99.8-104.5%. The results of this research indicate the feasibility and practicality of B,N-CDs as an effective fluorescent probe for the determination of morin.

Improved Endothelium-Dependent Relaxation of Thoracic Aorta in Niclosamide-Treated Diabetic Rats

Diabetes-induced endothelial dysfunction is critical for the development of diabetic cardiovascular complications. The aim of this study was to investigate the effect of niclosamide (Nic) on vascular endothelial dysfunction in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were injected with a single intraperitoneal injection of STZ (75 mg/kg) to induce type 1 diabetes, and Nic (10 mg/kg) was intraperitoneally administered per day for 4 weeks. Endothelial function was evaluated as carbachol (CCh, an endothelium-dependent vasodilator)-evoked relaxation in the experiments performed on isolated thoracic aortas. The changes in the protein expressions of phosphorylated eNOS at serine 1177 (p-eNOSSer1177) and phosphorylated VASP at serine 239 (p-VASPSer239) of the rat aortas were analyzed by western blotting to determine whether NO/cGMP signaling is involved in the mechanism of Nic. STZ-injected rats had higher fasting blood glucose and less body weight compared to control rats (p < 0.05). Nic treatment did not affect blood glucose levels or body weights of the rats. CCh-induced endothelium-dependent relaxation of the aortic rings was significantly decreased in diabetic rats compared to control (Emax = 66.79 ± 7.41% and 90.28 ± 5.55%, respectively; p < 0.05). CCh-induced relaxation response was greater in Nic-treated diabetic rats compared to diabetic rats (Emax = 91.56 ± 1.20% and 66.79 ± 7.41%, respectively; p < 0.05). Phosphorylation of eNOS and VASP in aortic tissues was significantly reduced in diabetic rats, which were markedly increased by Nic treatment (p < 0.05). We demonstrated that Nic improved endothelial dysfunction possibly through the activation of NO/cGMP signaling without affecting hyperglycemia in diabetic rats. Our results suggesting that Nic has potential of repurposing for diabetic cardiovascular complications.

Dietary Anti-Aging Polyphenols and Potential Mechanisms

For years, the consumption of a diet rich in fruits and vegetables has been considered healthy, increasing longevity, and decreasing morbidities. With the assistance of basic research investigating the potential mechanisms, it has become clear that the beneficial effects of plant-based foods are mainly due to the large amount of bioactive phenolic compounds contained. Indeed, substantial dietary intervention studies in humans have supported that the supplementation of polyphenols have various health-promoting effects, especially in the elderly population. In vitro examinations on the anti-aging mechanisms of polyphenols have been widely performed, using different types of natural and synthetic phenolic compounds. The aim of this review is to critically evaluate the experimental evidence demonstrating the beneficial effects of polyphenols on aging-related diseases. We highlight the potential anti-aging mechanisms of polyphenols, including antioxidant signaling, preventing cellular senescence, targeting microRNA, influencing NO bioavailability, and promoting mitochondrial function. While the trends on utilizing polyphenols in preventing aging-related disorders are getting growing attention, we suggest the exploration of the beneficial effects of the combination of multiple polyphenols or polyphenol-rich foods, as this would be more physiologically relevant to daily life.

A multitarget semi-synthetic derivative of the flavonoid morin with improved in vitro vasorelaxant activity: Role of CaV1.2 and KCa1.1 channels

Ca_V1.2 channels play a fundamental role in the regulation of vascular smooth muscle tone. The aim of the present study was to synthesize morin derivatives bearing the nitrophenyl moiety of dihydropyridine Ca²⁺ antagonists to increase the flavonoid vasorelaxant activity. The effects of morin and its derivatives were assessed on Ca_V1.2 and K_Ca1.1 channels, both in vitro and in silico, as well as on the contractile responses of rat aorta rings. All compounds were effective Ca_V1.2 channel blockers, positioning in the α_1C subunit region where standard blockers bind. Among the four newly synthesized morin derivatives, the penta-acetylated morin-1 was the most efficacious Ca²⁺ antagonist, presenting a vasorelaxant profile superior to that of the parent compound and, contrary to morin, antagonized also the release of Ca²⁺ from the sarcoplasmic reticulum; surprisingly, it also stimulated K_Ca1.1 channel current. Computational analysis demonstrated that morin-1 bound close to the K_Ca1.1 channel S6 segment. In conclusion, these findings open a new avenue for the synthesis of valuable multi-functional, vasorelaxant morin derivatives capable to target several pathways underpinning the pathogenesis of hypertension.

Chicoric acid attenuates hyperglycemia-induced endothelial dysfunction through AMPK-dependent inhibition of oxidative/nitrative stresses

BACKGROUND

Endothelial dysfunction is a driving force during the development and progression of cardiovascular complications in diabetes. Targeting endothelial injury may be an attractive avenue for the management of diabetic vascular disorders. Chicoric acid is reported to confer antioxidant and anti-inflammatory properties in various diseases including diabetes. However, the role and mechanism of chicoric acid in hyperglycemia-induced endothelial damage are not well understood.

METHODS

In the present study, human umbilical vein endothelial cells (HUVECs) were incubated with high glucose/high fat (HG + HF) to induce endothelial cell injury.

RESULTS

We found that exposure of HUVECs to HG + HF medium promoted the release of cytochrome c (cytc) from mitochondrion into the cytoplasm, stimulated the cleavage of caspase-3 and poly ADP-ribose-polymerase (PARP), then inducing cell apoptosis, the effects that were prevented by administration of chicoric acid. Besides, we found that chicoric acid diminished HG + HF-induced phosphorylation and degradation of IκBα, and subsequent p65 NFκB nuclear translocation, thereby contributing to its anti-inflammatory effects in HUVECs. We also confirmed that chicoric acid mitigated oxidative/nitrative stresses under HG + HF conditions. Studies aimed at exploring the underlying mechanisms found that chicoric acid activated the AMP-activated protein kinase (AMPK) signaling pathway to attenuate HG + HF-triggered injury in HUVECs as AMPK inhibitor Compound C or silencing of AMPKα1 abolished the beneficial effects of chicoric acid in HUVECs.

CONCLUSION

Collectively, chicoric acid is likely protected against diabetes-induced endothelial dysfunction by activation of the AMPK signaling pathway. Chicoric acid could be a novel candidate for the treatment of the diabetes-associated vascular endothelial injury.