Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance Ca(2+) -activated K(+) channels

Flavonoids: Potential therapeutic agents for cardiovascular disease

Flavonoids are found in the roots, stems, leaves, and fruits of many plant taxa. They are related to plant growth and development, pigment formation, and protection against environmental stress. Flavonoids function as antioxidants and exert anti-inflammatory effects in the cardiovascular system by modulating classical inflammatory response pathways, such as the TLR4-NF-ĸB, PI3K-AKT, and Nrf2/HO-1 signalling pathways. There is increasing evidence for the therapeutic effects of flavonoids on hypertension, atherosclerosis, and other diseases. The potential clinical value of flavonoids for diseases of the cardiovascular system has been widely explored. For example, studies have evaluated the roles of flavonoids in the regulation of blood pressure via endothelium-dependent and non-endothelium-dependent pathways and in the regulation of myocardial systolic and diastolic functions by influencing calcium homeostasis and smooth muscle-related protein expression. Flavonoids also have hypoglycaemic, hypolipidemic, anti-platelet, autophagy, and antibacterial effects. In this paper, the role and mechanism of flavonoids in cardiovascular diseases were reviewed in order to provide reference for the clinical application of flavonoids in the future.

Bioactive Flavonoids in Protecting Against Endothelial Dysfunction and Atherosclerosis

Atherosclerosis is a common cardiovascular disease closely associated with factors such as hyperlipidaemia and chronic inflammation. Among them, endothelial dysfunction serves as a major predisposing factor. Vascular endothelial dysfunction is manifested by impaired endothelium-dependent vasodilation, enhanced oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, endothelial senescence, and endothelial-mesenchymal transition (EndoMT). Flavonoids are known for their antioxidant activity, eliminating oxidative stress induced by reactive oxygen species (ROS), thereby preventing the oxidation of low-density lipoprotein (LDL) cholesterol, reducing platelet aggregation, alleviating ischemic damage, and improving vascular function. Flavonoids have also been shown to possess anti-inflammatory activity and to protect the cardiovascular system. This review focuses on the protective effects of these naturally-occuring bioactive flavonoids against the initiation and progression of atherosclerosis through their effects on endothelial cells including, but not limited to, their antioxidant, anti-inflammatory, anti-thrombotic, and lipid-lowering properties. However, more clinical evidences are still needed to determine the exact role and optimal dosage of these compounds in the treatment of atherosclerosis.

Naringin corrects renal failure related to Lesch-Nyhan disease in a rat model via NOS-cAMP-PKA and BDNF/TrkB pathways

This study explored the effect of naringin (NAR) on HGPRT1 deficiency and hyperuricemia through NOS-cAMP-PKA and BDNF/TrkB signaling pathways induced by caffeine (CAF) and KBrO3 in a rat model. Sixty-three adult male albino rats were randomly assigned into nine (n = 7) groups. Group I: control animals, Group II was treated with 100 mg/kg KBrO3 , Group III was treated with 250 mg/kg CAF, Group IV was treated with 100 mg/kg KBrO3  + 250 mg/kg CAF, Group V was administered with 100 mg/kg KBrO3  + 100 mg/kg haloperidol, Group VI was administered with 100 mg/kg KBrO3  + 50 mg/kg NAR, Group VII was administered with 500 mg/kg CAF + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO3  + 250 mg/kg CAF + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The exposure of rats to KBrO3 and CAF for 21 days induced renal dysfunction linked with Lesch-Nyhan disease. NAR obliterated renal dysfunction linked with Lesch-Nyhan disease by decreasing uric acid, renal malondialdehyde level, inhibiting the activities of arginase, and phosphodiesterase-51 (PDE-51) with corresponding upregulation of brain derived-neurotrophic factor and its receptor (BDNF-TrkB), Bcl11b, HGPRT1, and DARPP-32. Additionally, renal failure related to Lesch-Nyhan disease was remarkably corrected by NAR as shown by the reduced activities of AChE and enzymes of ATP hydrolysis (ATPase, AMPase, and ADA) with affiliated increase in the NO level. This study therefore validates NAR as nontoxic and effective chemotherapy against kidney-related Lesch-Nyhan disease by mitigating effects of toxic food additives and enzymes of ATP-hydrolysis via NOS-cAMP-PKA and BDNF/TrkB signaling pathways.

Anti-angiogenic effect of nano-formulated water soluble kaempferol and combretastatin in an in vivo chick chorioallantoic membrane model and HUVEC cells

The present study evaluated the efficacy of nano-formulated water-soluble kaempferol and combretastatin alone and combined against the native kaempferol and combretastatin on angiogenesis. The solvent evaporation method was used to synthesize the nano-formulated water-soluble kaempferol and combretastatin and characterized using various analyses such as dynamic light scattering (DLS) and Fourier-transform infrared (FT-IR) spectroscopy.The anti-angiogenic activity of native, nano-formulated water-soluble kaempferol and combretastatin was investigated by cell viability on HUVEC and A498 cell lines, while chick chorioallantoic membrane (CAM) assay was utilized to assess morphometric and histopathological changes, and mRNA expressions of VEGF-A and FGF2 using qRT-PCR. MTT assay results revealed that the combination of nano-formulated water-soluble kaempferol and combretastatin significantly reduced the cell viability compared to control, individual treatments of native, nano-formulated water-soluble kaempferol, and combretastatin. Morphometric analysis of CAM showed that treatment with nano-formulated water-soluble kaempferol and combretastatin caused a substantial decrease in density, vessel network, branch points, and nets of CAM blood vessels. The histopathological results of CAM showed the irregular shape of blood vessels at the thin stratum of chronic endoderm, and blood capillaries were diminished compared to the control. In addition, the mRNA expression levels of VEGF-A and FGF2 were significantly decreased compared with native forms. Therefore, the findings of this study indicate that nano-formulated water-soluble combretastatin and kaempferol suppress angiogenesis by preventing the activation of endothelial cells and suppressing factors of angiogenesis. Moreover, a combination of nano-formulated water-soluble kaempferol and combretastatin worked much better than individual treatments.

Flavonoids as Modulators of Potassium Channels

Potassium channels are widely distributed integral proteins responsible for the effective and selective transport of K+ ions through the biological membranes. According to the existing structural and mechanistic differences, they are divided into several groups. All of them are considered important molecular drug targets due to their physiological roles, including the regulation of membrane potential or cell signaling. One of the recent trends in molecular pharmacology is the evaluation of the therapeutic potential of natural compounds and their derivatives, which can exhibit high specificity and effectiveness. Among the pharmaceuticals of plant origin, which are potassium channel modulators, flavonoids appear as a powerful group of biologically active substances. It is caused by their well-documented anti-oxidative, anti-inflammatory, anti-mutagenic, anti-carcinogenic, and antidiabetic effects on human health. Here, we focus on presenting the current state of knowledge about the possibilities of modulation of particular types of potassium channels by different flavonoids. Additionally, the biological meaning of the flavonoid-mediated changes in the activity of K+ channels will be outlined. Finally, novel promising directions for further research in this area will be proposed.

Disorders of Hippocampus Facilitated by Hypertension in Purine Metabolism Deficiency is Repressed by Naringin, a Bi-flavonoid in a Rat Model via NOS/cAMP/PKA and DARPP-32, BDNF/TrkB Pathways

Individuals who are hypertensive have a higher tendency of predisposition to other genetic diseases including purine metabolism deficiency. Therefore, the search for nontoxic and effective chemo protective agents to abrogate hypertension-mediated genetic disease is vital. This study therefore investigated the repressive effect of naringin (NAR) against disorder of hippocampus facilitated by hypertension in purine metabolism deficiency. Male albino rats randomly assigned into nine groups (n = 7) were treated for 35 days. Group I: control animals, Group II was treated with 100 mg/kg KBrO₃, Group III was treated with 250 mg/kg caffeine, and Group IV was treated with 100 mg/kg KBrO₃ + 250 mg/kg caffeine. Group V was administered with 100 mg/kg KBrO₃ + 100 mg/kg haloperidol. Group VI was administered with 100 mg/kg KBrO₃ + 50 mg/kg NAR. Group VII was administered with 250 mg/kg caffeine + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO₃ + 250 mg/kg caffeine + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The sub-acute exposure to KBrO₃ and CAF induced hypertension and mediated impairment in the hippocampus cells. This was apparent by the increase in PDE-5¹, arginase, and enzymes of ATP hydrolysis (ATPase and AMPase) with a simultaneous increase in cholinergic (AChE and BuChE) and adenosinergic (ADA) enzymes. The hypertensive-mediated hippocampal impairment was associated to alteration of NO and AC signaling coupled with lower expression of brain-derived neurotrophic factor and its receptor (BDNF-TrkB), down regulation of Bcl11b and DARPP-32 which are neurodevelopmental proteins, and hypoxanthine accumulation. However, these features of CAF-mediated hippocampal damage in KBrO₃-induced hypertensive rats were repressed by post-treatment with NAR via production of neuro-inflammatory mediators, attenuation of biochemical alterations, stabilizing neurotransmitter enzymes, regulating NOS/cAMP/PKA and DARPP-32, BDNF/TrkB signaling, and restoring hippocampal tissues.

Kaempferol and atherosclerosis: From mechanism to medicine

Natural products possess pleiotropic cardiovascular protective effects owing to their anti-oxidation, anti-inflammation and anti-thrombotic properties. Kaempferol, (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), is a kind of naturally occurring flavonoid existing in many common fruits and vegetables (e.g., onions, broccoli, strawberries and grapes) and particularly in traditional Chinese medicine as exemplified by Ginkgo biloba. Epidemiological, preclinical and clinical studies have revealed an inverse association between the consumption of kaempferol-containing foods and medicines and the risk of developing cardiovascular diseases. Numerous translational studies in experimental animal models and cultured cells have demonstrated a wide range of pharmacological activities of kaempferol. In this article, we reviewed the antioxidant, anti-inflammatory and cardio-protective activities of kaempferol and elucidated the potential molecular basis of the therapeutic capacity of kaempferol by focusing on its anti-atherosclerotic effects. Overall, the review presents the health benefits of kaempferol-containing plants and medicines and reflects on the potential of kaempferol as a possible drug candidate to prevent and treat atherosclerosis, the underlying pathology of most cardiovascular diseases.

3'-Oxo-tabernaelegantine A (OTNA) selectively relaxes pulmonary arteries by inhibiting AhR

BACKGROUND

Pulmonary arterial hypertension (PAH), characterized by pulmonary artery constriction and vascular remodeling, has a high mortality rate. New drugs for the treatment of PAH urgently need to be developed.

PURPOSE

This study was designed to investigate the vasorelaxant activity of OTNA in isolated pulmonary arteries, and explore its molecular mechanism.

METHODS

Pulmonary arteries and thoracic aortas were isolated from mice, and vascular tone was tested with a Wire Myograph System. Nitric oxide levels were determined with DAF-FM DA and DAX-J2™ Red. Cellular thermal shift assays, microscale thermophoresis, and molecular docking were used to identify the interaction between OTNA and aryl hydrocarbon receptor (AhR). The levels of PI3K, p-PI3K, Akt, p-Akt, eNOS, p-eNOS, and AhR were analyzed by Western blotting.

RESULTS

OTNA selectively relaxed the isolated pulmonary artery rings in an endothelium-dependent manner. Mechanistic study showed that OTNA induced NO production through activation of the PI3K/Akt/eNOS pathway in endothelial cells. Furthermore, we also found that OTNA directly bound to AhR and activated the PI3K/Akt/eNOS pathway to dilate pulmonary arteries by inhibiting AhR.

CONCLUSIONS

OTNA relaxes pulmonary arteries by antagonizing AhR. This study provides a new natural antagonist of AhR as a promising lead compound for PAH treatment.

The antihypertensive potential of flavonoids from Chinese Herbal Medicine: A review

With the coming of the era of the aging population, hypertension has become a global health burden to be dealt with. Although there are multiple drugs and procedures to control the symptoms of hypertension, the management of it is still a long-term process, and the side effects of conventional drugs pose a burden on patients. Flavonoids, common compounds found in fruits and vegetables as secondary metabolites, are active components in Chinese Herbal Medicine. The flavonoids are proved to have cardiovascular benefits based on a plethora of animal experiments over the last decade. Thus, the flavonoids or flavonoid-rich plant extracts endowed with anti-hypertension activities and probable mechanisms were reviewed. It has been found that flavonoids may affect blood pressure in various ways. Moreover, despite the substantial evidence of the potential for flavonoids in the control of hypertension, it is not sufficient to support the clinical application of flavonoids as an adjuvant or core drug. So the synergistic effects of flavonoids with other drugs, pharmacokinetic studies, clinical trials and the safety of flavonoids are also incorporated in the discussion. It is believed that more breakthrough studies are needed. Overall, this review may shed some new light on the explicit recognition of the mechanisms of anti-hypertension actions of flavonoids, pointing out the limitations of relevant research at the current stage and the aspects that should be strengthened in future researches.

Targeting mitochondrial ion channels for cancer therapy

Pharmacological targeting of mitochondrial ion channels is emerging as a promising approach to eliminate cancer cells; as most of these channels are differentially expressed and/or regulated in cancer cells in comparison to healthy ones, this strategy may selectively eliminate the former. Perturbation of ion fluxes across the outer and inner membranes is linked to alterations of redox state, membrane potential and bioenergetic efficiency. This leads to indirect modulation of oxidative phosphorylation, which is/may be fundamental for both cancer and cancer stem cell survival. Furthermore, given the crucial contribution of mitochondria to intrinsic apoptosis, modulation of their ion channels leading to cytochrome c release may be of great advantage in case of resistance to drugs triggering apoptotic events upstream of the mitochondrial phase. In the present review, we give an overview of the known mitochondrial ion channels and of their modulators capable of killing cancer cells. In addition, we discuss state-of-the-art strategies using mitochondriotropic drugs or peptide-based approaches allowing a more efficient and selective targeting of mitochondrial ion channel-linked events.

Ajuga iva water extract antihypertensive effect on stroke-prone spontaneously hypertensive rats, vasorelaxant effects ex vivo and in vitro activity of fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Ajuga iva (L.) Schreb. (Labiatae) (AI) is used in folk medicine for a variety of ailments, including diabetes mellitus and hypertension.

AIM OF THE STUDY

In this work, we aimed to investigate the antihypertensive and vasorelaxant effects of AI aqueous extract in stroke prone spontaneously hypertensive rats (SHR-SP).

MATERIAL AND METHODS

Male SHR-SP rats were orally force-fed AI aqueous extract (500 mg/kg body weight) daily for one week. Systolic blood pressure and urine output were recorded in vivo by non-invasive methods. AI vasoactive effects on noradrenaline contractile response and acetylcholine-evoked relaxation were assessed ex vivo on aorta rings of treated and untreated SHR-SP rats. AI extract was then subjected to bio-guided fractionation using solvents of increasing polarity. For each fraction, in vitro vasorelaxation assay was performed on noradrenaline-precontracted aorta of Wistar rats, in the absence/presence of N-nitro-L-arginine (L-NNA). HPLC analysis of AI total extract, and the most in vitro active AI residual aqueous extract fraction (A1) was performed using naringin, naringenin, apigenin, apigenin 7-O-glucoside as marker compounds.

RESULTS

AI aqueous extract (500 mg/kg) significantly (P < 0.05) decreased systolic blood pressure (SBP) in SHR-SP rats, while not affecting the urine output. In ex vivo experiments, the total extract decreased contractile response to noradrenaline of aortic rings isolated from AI-treated SHR-SP rats with or without addition of N-nitro-L-arginine, but endothelium dependent relaxation evoked by acetylcholine in noradrenaline-contracted aortic rings was not affected by the extract treatment. In vitro experiments on AI aqueous extract fractions showed that its polar fraction was the only one affecting in vitro noradrenaline induced contractions, but only in an endothelium dependent manner. This fraction was shown by HPLC-UV to contain flavonoid glycosides among other polar compounds whose activity and mode of action may be modified in vivo by metabolization.

CONCLUSION

These results support the use of AI as antihypertensive treatment in folk medicine. The systolic blood pressure decrease may be attributed at least in part to vasorelaxant glycosylated/polar phenolic compounds as flavonoids and/or their metabolites.

The anti-asthmatic potential of flavonol kaempferol in an experimental model of allergic airway inflammation

Flavonol kaempferol possesses a broad spectrum of potent pharmacological activities that seem to be effective in the modulation of allergic respiratory diseases. In our study, an experimental animal model of ovalbumin (OVA)-induced allergic airway inflammation in guinea pigs was used to determine the anti-asthmatic potential of kaempferol. The parameters of specific airway resistance (sRaw) and cough reflex response were evaluated in vivo. In vitro, an assessment of tracheal smooth muscle (TSM) contractility and analyses of inflammatory cytokines (IL-4, IL-5, IL-13, GM-CSF, IFN-γ), transforming growth factor (TGF-β1), immune cells count and ciliary beating frequency (CBF) were performed. Both single (6, 20 mg/kg b. w. p. o.) and long-term administered doses of kaempferol (20 mg/kg b. w. p. o., 21 days) suppressed sRaw provoked by histamine in conscious animals. The administration of kaempferol for 21 days attenuated histamine-induced TSM contractility in vitro and ameliorated the progression of chronic airway inflammation by decreasing the levels of IL-5, IL-13, GM-CSF, eosinophil count in bronchoalveolar lavage (BAL) fluid and TGF-β1 protein level in lung tissue. Kaempferol also eliminated the alterations in cough reflex sensitivity invoked by OVA-sensitization, but it did not affect CBF. The results demonstrate that flavonol kaempferol can modulate allergic airway inflammation and associated asthma features (AHR, aberrant stimulation of cough reflex).

Mechanisms involved in the endothelium-dependent vasodilatory effect of an ethyl acetate fraction of Cyathea phalerata Mart. in isolated rats’ aorta rings

The species Cyathea phalerata Mart. is a tree fern, commonly known as “xaxim”, which is found in tropical and subtropical areas of Brazil. The present study investigated the mechanisms related with the vasorelaxant effects of an Ethyl Acetate Fraction (EAF) obtained from C. phalerata in rats’ thoracic aorta rings. In pre-contracted vessels, EAF (0.1–1000 μg/mL) caused a concentration-dependent relaxation. The endothelium denudation, the nitric oxide (NO) synthase and guanylyl cyclase inhibitor reduced the vasodilation, indicating the participation of NO/cGMP pathway in its effect. The relaxation of EAF was abolished in the absence of extracellular Ca²⁺ and was significantly decreased in the presence of Ca²⁺ entry blocker, suggesting that Ca²⁺ influx plays an important role in EAF effect and probably in eNOS activity. However, the PI3K/Akt pathway is not responsible for eNOS phosphorylation/activation. The vasodilator effect of EAF was partially inhibited by KCl 40 mM and almost totally abolished with L-NOARG + KCl 40 mM, indicating also the role of hyperpolarization in its effect. Calcium activated K⁺ channels are not involved in the EAF-induced hyperpolarization. The COX inhibitor, indomethacin, slightly reduced the vasodilation induced by EAF. In addition, EAF did not alter the relaxant effects of NO-donor, indicating that the relaxant activity cannot be attributed to free radical-scavenging properties. In conclusion, the present study showed that the EAF, causes an endothelium-dependent vasorelaxant effect in aorta that mainly involves the NO-cGMP pathway, hyperpolarization and prostanoids. The vasorelaxant activity of EAF can be attributed to the occurrence of polyphenol compounds.

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An ethyl acetate fraction obtained from Cyathea phalerata induces vasodilatation.

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EAF induced relaxation by an endothelium-dependent mechanism.

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EAF increases the NO production and hyperpolarization that evoke vasodilation.

Naringin regulates erectile dysfunction by abolition of apoptosis and inflammation through NOS/cGMP/PKG signalling pathway on exposure to Bisphenol-A in hypertensive rat model

This study investigated the effect of naringin (NRG) on extracellular metabolism of ATP through the NOS/cGMP/PKG signaling pathway induced by Nω-nitro-L-arginine methyl ester hydrochloride (_L-NAME) on exposure to Bisphenol-A (BPA) in penis. Fifty-six adult male albino rats were randomly distributed into eight (n = 7) groups. Group I: control animals, Group II was treated with 40 mg/kg _L-NAME, Group III was treated with 50 mg/kg BPA, Group IV was treated with 40 mg/kg _L-NAME +50 mg/kg BPA. Group V was administered with 40 mg/kg _L-NAME +80 mg/kg NRG. Group VI was administered with 50 mg/kg BPA + 80 mg/kg NRG. Group VII was administered with 40 mg/kg _L-NAME+50 mg/kg BPA + 80 mg/kg NRG. Lastly, group VIII was treated with 80 mg/kg NRG for 14 days. NRG prevented hypertension and erectile dysfunction by inhibiting the activities of angiotensin-converting enzymes, arginase, and phosphodiesterase-5¹ (PDE-5¹) with corresponding down-regulation of inflammatory markers including TNF-α and IL-B. Additionally, hypertensive erectile dysfunction was remarkably prevented by NRG as manifested by the declined activities of AChE, MAO-A and enzymes of ATP hydrolysis (ATPase, ADPase, AMPase and ADA) with resultant increase in NO level. Also, penile expression of antigen presenting cells, CD43 transcript, caspace-9 and tumor suppressor P53 proteins were repressed on treatment with NRG. This study validates the hypothesis that NRG may be a valuable remedy in abrogating penile inflammatory markers, apoptosis and enzymes of ATP-hydrolysis via NOS/cGMP/PKG signaling pathways in hypertensive rat model on exposure to environmental toxicant.

Optimization of an Extraction Solvent for Angiotensin-Converting Enzyme Inhibitors from Hibiscus sabdariffa L. Based on Its UPLC-MS/MS Metabolic Profiling

Hibiscus species (Malvaceae) have been long used as an antihypertensive folk remedy. The aim of our study was to specify the optimum solvent for extraction of the angiotensin-converting enzyme inhibiting (ACEI) constituents from Hibiscus sabdariffa L. The 80% methanol extract (H2) showed the highest ACEI activity, which exceeds that of the standard captopril (IC50 0.01255 ± 0.00343 and 0.210 ± 0.005 µg/mL, respectively). Additionally, in a comprehensive metabolomics approach, an ultra-performance liquid chromatography (UPLC) coupled to the high resolution tandem mass spectrometry (HRMS) method was used to trace the metabolites from each extraction method. Interestingly, our comprehensive analysis showed that the 80% methanol extract was predominated with secondary metabolites from all classes including flavonoids, anthocyanins, phenolic and organic acids. Among the detected metabolites, phenolic acids such as ferulic and chlorogenic acids, organic acids such as citrate derivatives and flavonoids such as kaempferol have been positively correlated to the antihypertensive potential. These results indicates that these compounds may significantly contribute synergistically to the ACE inhibitory activity of the 80% methanol extract.

Kaempferol protects mitochondria and alleviates damages against endotheliotoxicity induced by doxorubicin

Kaempferol (Kae), a flavonoid, has been found in fruits and other vegetables, possesses many biological activities. 14-3-3 protein exerts protection on various types of injured tissues and cells. Doxorubicin (Dox) causes excessive reactive oxygen species (ROS) generation, which induces endotheliotoxicity and cardiotoxicity. We hypothesized that Kae could protect vascular endothelium by regulating 14-3-3γ or related pathways against Dox toxicity. HUVECs were established Dox-toxic injury models. Kae's effects were assessed with many physiological, enzymatic, cellular, and molecular biological indexes. Our results showed that Dox-induced damage in HUVECs were reduced through Kae to promote the expression of total protein 14-3-3γ and mitochondrial Bcl-2, phosphorylate Bad, increase cell viability, NO content, DDAHⅡactivity, p-eNOS/eNOS ratio, and MMP levels, maintained NAD⁺/NADH and GSH/GSSG balance, and decrease LDH and caspase-3 activities, ADMA content, ROS generation, mPTP openness, and apoptosis. Kae's effects were abolished with pAD/14-3-3γ-shRNA downregulating 14-3-3γ expression, or ABT-737 inhibiting Bcl-2 activity. This study demonstrated that Kae protected the vascular endothelium against Dox-induced damage by regulating 14-3-3γ and ADMA/DDAHⅡ/eNOS/NO pathway, inhibiting oxidative stress, and improving mitochondrial function.

Compared Phenolic Compound Contents of 22 Commercial Fruit and Vegetable Juices: Relationship to ex-vivo Vascular Reactivity and Potential in vivo Projection

The real impact of polyphenol-rich vegetable and fruit juice intake on cardiovascular health remains a matter of controversy. In the present study, rat aorta segments immersed in an organ bath (OB) were used to explore whether the total polyphenol content and/or individual phenolic compound contents of 22 commercial vegetable (n = 3) and fruit juices [(citrus (n = 5), berries (n = 10), apple (n = 2), pineapple (n = 2)] might be associated with vascular tone. Red juices (particularly blackcurrant) and lemon juice caused the most marked vasorelaxation, its amplitude being endothelium dependent or not according to the volume ratio of juice to initial OB solution V_juice/V_OBS). At volume ratios 5% and 10%, both the juice and OB total polyphenol for all juices and total anthocyanin contents for berry juices significantly correlated with aorta vasorelaxation intensity. This was not the case for total or individual flavonols (except kaempferol) or for total or individual flavanols (except epigallocatechin gallate). If one relates our measured concentrations of individual phenolic compounds in OB to what is known about their physiological concentrations, and given our evidenced correlations between compound concentrations and vasorelaxation intensity, kaempferol, epigallocatechin gallate and peonidin-3-O-glucoside seem to emerge as the interesting phenolic compounds likely to be responsible for the potent vasorelaxation observed with fruit juices, and more particularly blackcurrant ones. Clinical investigation is required, however, to confirm our observations.

Bauhinia forficata link, a Brazilian medicinal plant traditionally used to treat cardiovascular disorders, exerts endothelium-dependent and independent vasorelaxation in thoracic aorta of normotensive and hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Bauhinia forficata Link, commonly known as "cow's paw", is a native plant from South America. Its leaves are widely used in Brazilian folk medicine to treat diabetes and cardiovascular disorders. Although this species' biological potential has been extensively proven as an antidiabetic, anti-inflammatory and antioxidant agent, there is a lack of studies to evidence its action on the cardiovascular system.

AIM OF THE STUDY

This study was designed to investigate the vascular effects of B. forficata leaves preparations and its majority compound kaempferitrin, as well as its aglycone form kaempferol, in rat aortic rings of normotensive (NTR) and hypertensive (SHR) rats.

MATERIALS AND METHODS

Aorta rings from NTR and SHR precontracted with phenylephrine were exposed to cumulative concentrations of B. forficata extract, fractions (1-50 μg/mL) and compounds (0.001-0.3 μg/mL). The mechanisms involved in the vasorelaxant effect of ethyl-acetate plus butanol fraction (EAButF) were also evaluated.

RESULTS

Although kaempferitrin is the most abundant compound found in both methanolic extract and EAButF, 24 minor phenolic compounds were identified in B. forficata leaves, including kaempferol. EAButF was the only with endothelium-dependent and independent vasorelaxant properties in both NTR and SHR. The incubation with L-NAME or ODQ completely blocked EAButF-induced vasorelaxation. On the other hand, the incubation with propranolol, atropine, indomethacin, glibenclamide or barium chloride did not change the vasorelaxant activity of EAButF (50 μg/mL). Nevertheless, the incubation with tetraethylammonium and 4-aminopyridine significantly influenced the EAButF activity. It was also shown that Ca²⁺ influx or efflux is not related to EAButF vasorelaxation potential. Kaempferitrin and kaempferol were also able to relax the rat aortic rings in 34.70% and 40.54%, respectively.

CONCLUSIONS

This study shows, for the first time, the vasorelaxant effect of EAButF from B. forficata leaves, an effect that may be attributed to the modulation of vascular tone through nitric oxide/soluble guanylate cyclase pathway, and potassium channels. The bioactive kaempferitrin and kaempferol seem to be important for the effects observed with the fraction. Finally, preparations obtained from the leaves of B. forficata may be interesting candidates for new or complementary strategies regarding cardiovascular diseases.

Astragalin augments basal calcium influx and insulin secretion in rat pancreatic islets

Astragalin is a flavonol glycoside with several biological activities, including antidiabetic properties. The objective of this study was to investigate the effects of astragalin on glycaemia and insulin secretion, in vivo, and on calcium influx and insulin secretion in isolated rat pancreatic islets, ex vivo. Astragalin (1 and 10 mg / kg) was administered by oral gavage to fasted Wistar rats and serum glucose and plasma insulin were measured. Isolated pancreatic islets were used to measure basal insulin secretion and calcium influx. Astragalin (10 mg/ kg) decreased glycaemia and increased insulin secretion significantly at 15-180 min, respectively, in the glucose tolerance test. In isolated pancreatic cells, astragalin (100 μM) stimulated calcium influx through a mechanism involving ATP-dependent potassium channels, L-type voltage-dependent calcium channels, the sarcoendoplasmic reticulum calcium transport ATPase (SERCA), PKC and PKA. These findings highlight the dietary coadjuvant, astragalin, as a potential insulin secretagogue that may contribute to glucose homeostasis.

Chemo-preventive and therapeutic effect of the dietary flavonoid kaempferol: A comprehensive review

Kaempferol, a natural flavonoid present in several plants, possesses a wide range of therapeutic properties such as antioxidant, anticancer, and anti-inflammatory. It has a significant role in reducing cancer and can act as a therapeutic agent in the treatment of diseases and ailments such as diabetes, obesity, cardiovascular diseases, oxidative stress, asthma, and microbial contamination disorders. Kaempferol acts through different mechanisms: It induces apoptosis (HeLa cervical cancer cells), decreases cell viability (G2/M phase), downregulates phosphoinositide 3-kinase (PI3K)/AKT (protein kinase B) and human T-cell leukemia/lymphoma virus-I (HTLV-I) signaling pathways, suppresses protein expression of epithelial-mesenchymal transition (EMT)-related markers including N-cadherin, E-cadherin, Slug, and Snail, and metastasis-related markers such as matrix metallopeptidase 2 (MMP-2). Accordingly, the aim of the present review is to collect information pertaining to the effective role of kaempferol against various degenerative disorders, summarize the antioxidant, anti-inflammatory, anticancer, antidiabetic, and antiaging effects of kaempferol and to review the progress of recent research and available data on kaempferol as a protective and chemotherapeutic agent against several ailments.

Mechanisms underlying vasorelaxation induced in the porcine coronary arteries by Thymus linearis, Benth

ETHNOPHARMACOLOGICAL RELEVANCE

Thymus linearis, Benth indigenous to Pakistan has been traditionally used for the treatment of various diseases including hypertension.

AIM OF THE STUDY

Present study aims to investigate vasorelaxant effect of Thymus linearis and its underlying vasorelaxation mechanisms in porcine coronary artery rings.

MATERIALS AND METHODS

Aqueous-methanolic extract of aerial parts of Thymus linearis was prepared by maceration process and then bio-guided fractionation was carried out using different solvents. The effects of extract and subsequent fractions were assessed on coronary artery rings with intact and denuded endothelium. The mechanisms of vasorelaxant effect were investigated using different pharmacological tools. The in-vitro inhibitory effects of the test fractions were also assessed on purified phophodiestrases using radioenzymatic assay. Phytochemical studies were carried out using GCMS.

RESULTS

The aqueous-methanolic extract elicited similar relaxations in coronary artery rings with and without endothelium in dose dependent fashion and removal of endothelium did not alter this response. Further, n-butanolic fraction of Thymus liniaris (TLB) was found to be the most potent among other derived fractions. TLB did not alter the relaxation produced by endothelium dependent vasodilators in rings with intact endothelium. However, TLB significantly potentiated the relaxation elicited by cyclic AMP and cyclic GMP elevating drugs but not those to soluble guanylyl cyclase activators (YC-1 and BAY 41-2272) and K⁺ channel openers (levcromakalim and 1-EBIO). Pretreatment with TLB inhibited in a concentration-dependent manner contractions to KCl, CaCl₂ and U46619 in coronary artery rings without endothelium. Further, TLB was found to non-selectively inhibit the PDE activity in concentration manner.

CONCLUSION

n-Butanolic fraction of Thymus linearis possesses endothelium independent vasorelaxant effects in coronary artery by direct acting on the smooth muscles. These effects involve the elevation of the cyclic AMP and cyclic GMP possibly through the inhibition of various PDEs. GCMS analysis revel presence of thymole and carvacrol as major constituents. Furthermore, these investigations also support the folklore use of Thymus linearis in hypertension.

Quantitative and systems pharmacology 4. Network-based analysis of drug pleiotropy on coronary artery disease

Despite recent advance of therapeutic development, coronary artery disease (CAD) remains one of the major issues to public health. The use of genomics and systems biology approaches to inform drug discovery and development have offered the possibilities for new target identification and in silico drug repurposing. In this study, we propose a network-based, systems pharmacology framework for target identification and drug repurposing in pharmacologic treatment and chemoprevention of CAD. Specifically, we build in silico models by integrating known drug-target interactions, CAD genes derived from the genetic and genomic studies, and the human protein-protein interactome. We demonstrate that the proposed in silico models can successfully uncover approved drugs and novel natural products in potentially treating and preventing CAD. In case studies, we highlight several approved drugs (e.g., fasudil, parecoxib, and dexamethasone) or natural products (e.g., resveratrol, luteolin, daidzein and caffeic acid) with new mechanism-of-action in chemical intervention of CAD by network analysis. In summary, this study offers a powerful systems pharmacology approach for target identification and in silico drug repurposing on CAD.

Effects of brinzolamide on rabbit ocular blood flow in vivo and ex vivo

AIM

To investigate if significant improvement of optic disc blood flow (ODBF) occurs after instillation of brinzolamide onto rabbit eyes.

METHODS

Testing of bilateral intraocular pressure (IOP) and left ODBF in 10 male rabbits took place every 3h over a 24h period. Brinzolamide (1% ophthalmic solution, two drops at 9:00 and 21:00) was administered to the left eye. ODBF, assessed using laser speckle flowgraphy, was determined as the mean blur rate (MBR). Furthermore, the effect of brinzolamide on isolated rabbit ciliary arteries using isometric tension recording system was performed.

RESULTS

After brinzolamide instillation, IOP was significantly decreased in the left eye. MBR-vessel was greater at 18:00 and 21:00 (P<0.05) than in the controls. MBR-tissue and MBR-average were greater at 18:00 (P<0.05) than in the controls. For isolated arteries pre-contracted with a high-K solution, brinzolamide induced concentration-dependent relaxation, reaching 46.1%±9% (n=21) at 1 mmol/L. In Ca²⁺-free solutions, incubation with brinzolamide suppressed 1 µmol/L histamine-induced contractions (P<0.05).

CONCLUSION

Brinzolamide decreases IOP and increases ocular blood flow. The direct vasodilatory effect of brizolamide is mediated by suppression of Ca²⁺ release from intracellular calcium stores.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

Sufentanil attenuates impairment of the endothelium-dependent vasodilation induced by hypoxia-reoxygenation in the rat coronary artery

Sufentanil has been used broadly in cardiac surgery, but the mechanisms by which it modulates coronary vascular tone after ischemia-reperfusion injury are largely unknown. Effects of sufentanil on coronary tone and on the relaxation of rat coronary arteries (CAs) in response to endothelium-dependent (acetylcholine) and endothelium-independent (sodium nitroprusside) relaxing agents in the presence of hypoxia-reoxygenation (H/R) was studied in an in vitro organ chamber setup. Sufentanil (10^-7-10^-4 mol/L) relaxed rat CA rings in endothelium-dependent and endothelium-independent manners. In endothelium-intact rings, preincubation of H/R-treated CAs with sufentanil (10^-5 mol/L) significantly increased the acetylcholine response, but did not augment sodium nitroprusside-induced relaxation. Sufentanil-mediated potentiation of acetylcholine-induced relaxation was not affected by a nitric oxide synthase inhibitor or by intermediate- or small-conductance Ca²⁺-activated K⁺ channel blockers. However, potentiation was abolished by iberiotoxin (100 nmol/L), a selective inhibitor of large-conductance Ca²⁺-activated K⁺ channels, as well as Rp-cAMPS (30 μmol/L), a cyclic AMP-dependent protein kinase (PKA) inhibitor. Sufentanil induced endothelium-dependent and endothelium-independent relaxation and attenuated H/R-induced impairment of endothelium-dependent vasodilation in the rat CAs. The potentiating effect of sufentanil may involve activation of large-conductance Ca²⁺-activated K⁺ channels via cAMP-dependent mechanisms.

Polyphenols: a Promising Nutritional Approach to Prevent or Reduce the Progression of Prehypertension

Diet plays a crucial role in maintaining healthy blood pressure. Functional foods are increasingly popular among health-conscious consumers to reduce cardiovascular risk factors and improve vascular health. In particular, dietary polyphenols represent an extraordinary inventory of structurally different compounds that may represent promising candidate chemical entities to prevent or delay the onset of hypertension. In recent years, it has been recognized that prehypertension may be a predictor of clinical hypertension and consequently of cardiovascular risk. Moreover, prehypertension status is associated with increased levels of several inflammatory markers and it is also characterized by structural changes, including endothelial dysfunction and arteriolar hypertrophy. Despite the low bioavailability of polyphenols and the lack of clinical data from nutritional intervention studies, the antihypertensive role of polyphenols to control blood pressure and reduce inflammation and endothelial dysfunction has been subject of recent debate. The purpose of this article is to discuss the potential benefits of dietary polyphenols as a promising and effective nutritional strategy for the management of prehypertension.

Smooth muscle relaxant activity of Crocus sativus (saffron) and its constituents: possible mechanisms

Saffron, Crocus sativus L. (C. sativus) is rich in carotenoids and used in traditional medicine for treatment of various conditions such as coughs, stomach disorders, amenorrhea, asthma and cardiovascular disorders. These therapeutic effects of the plant are suggested to be due to its relaxant effect on smooth muscles. The effect of C. sativus and its constituents on different smooth muscles and the underlying mechanisms have been studied. Several studies have shown the relaxant effects of C. sativus and its constituents including safranal, crocin, crocetin and kaempferol on blood vessels. In addition, it was reported that saffron stigma lowers systolic blood pressure. The present review highlights the relaxant effects of C. sativus and its constituents on various smooth muscles. The possible mechanisms of this relaxing effect including activation of ß2-adrenoceptors, inhibition of histamine H1 and muscarinic receptors and calcium channels and modulation of nitric oxide (NO) are also reviewed.