Electropharmacological actions of Ginkgo biloba extract on vascular smooth and heart muscles

In vitro Evaluation of the Nematicidal Efficacy of Quercetin on Adult Toxocara canis

PURPOSE

Toxocara canis is a globally distributed zoonotic parasite found in dogs' intestines, leading to various pathological damages, particularly to the intestinal flora. The larval stage causes human toxocariasis, especially in children, and may result in neurological disorders and blindness. Quercetin is a flavonoid with strong secondary metabolites and possesses medicinal advantages and antiparasitic qualities.

METHODS

The assay involved  four groups, each of  10 young adult T. canis; Group I was incubated in concentrations of an ethanolic extract of quercetin, Group II in albendazole (0.2 mM/ml) (+ve control), Group III in RPMI 1640 medium with ethanol (control), and Group IV in RPMI 1640 medium only (-ve control). The potential action of quercetin against adult T. canis in vitro was detected using scanning electron microscopy, histological investigations, and enzyme analysis.

RESULTS

SEM declared that exposure to LC90 of quercetin caused body shrinkage, cuticle and caudal papillae swelling, and disfigurement and erosion of cuticular annulations. Compared to albendazole's effect on the treated worm's body wall, results showed that quercetin generates oxidative stress and has an extensive and variable effect on T. canis organs, including the body wall, the gut, and the genitalia.

CONCLUSION

Quercetin may set the stage for a new class of medications with remarkable potential for treating parasitic nematodes in dogs and could be extended to humans. This is the first time to employ a comprehensive study illuminating the potential action of quercetin against adult Toxocara canis in vitro.

Biochemical validation for the therapeutic use of Plumeria rubra in coagulation disorders: a study combining in silico, in vitro, and in vivo approaches

Local healers in South Asia use Plumeria rubra Linn. leaves to treat various coagulation disorders in animals and humans. This study (in silico, in vitro, and in vivo) aimed to explore the pharmacological basis for the possible thrombolytic and anticlotting properties of the leaf extract of P. rubra. Phytoconstituents of P. rubra were dock against coagulation proteins: prothrombin, thromboplastin, and fibrin using in silico approach. Phytochemical screening, HPLC, and antioxidant, anticoagulant, and thrombolytic potential were evaluated using in vitro approach. Healthy male rabbits were divided into five groups (six rabbits each). Groups 1-3 were treated with aqueous-methanolic (30:70%) extract of P. rubra at 200, 300, and 600 mg/mL respectively groups in contrast to the positive and negative control groups. Thrombolytic activity was assessed at doses of 200, 300, and 600 µg/mL in comparison with standard urokinase (600 µg/kg). Platelet adhesion was evaluated at a dose of 200, 300, and 600 µg/mL against adrenaline (2 µM) and acute oral dose toxicity was assessed using in vivo approach. In silico study resulted in an excellent binding affinity and showed significant interaction with coagulation proteins. Phytochemical analysis showed a range of phytochemical classes: alkaloids, tannins, flavonoids, glycosides, anthraquinones, and saponins. HPLC analysis confirmed the phytoconstituents plumericin, rutin, kaempferol, and isoquercetin already reported for coagulation disorders. P. rubra showed excellent antioxidant potential and was assessed using DPPH, NO, and SOD assays. The activated partial thromboplastin time (APTT), bleeding time (BT), prothrombin time (PT), and clotting time (CT) all went up with increasing doses in the aqueous-methanolic extract (p ≤ 0.05). Comparing the plant extract to urokinase, the plant extract demonstrated considerable (p ≤ 0.05) clot lysis. Additionally, it dose-dependently delayed the ADR-induced platelet adhesion dose-dependently (p ≤ 0.05). The outcome of this study justifies its therapeutic utility in coagulation disorders and can be used as an alternative medicine.

Identification and quantification of the antioxidants in Ginkgo biloba leaf

The antioxidant activity of Ginkgo biloba leaf (GBL) extract is closely related to its efficacy against various diseases; however, the antioxidant activities of the specific constituents of GBL remain unclear. In this study, 194 GBL constituents were identified using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry, including 97 flavonoids, 37 terpenoids, 29 lignans, 19 carboxylic acids, 5 alkylphenolic acids, 5 alkylphenols, and 2 other compounds. The cleavage rules of the main constituents of GBL were dissected in detail. The 36 GBL constituents with high antioxidant activity were subsequently discovered using the oxygen radical absorbance capacity assay, including 30 flavonoids and six carboxylic acids. Finally, an HPLC analysis method was established to determine the content of the nine major antioxidants in the three batches of GBL. Among them, kaempferol 3-O-β-D-(6″-p-coumaroyl) glucopyranosyl-(1-2)-α-L-rhamnopyranoside, kaempferol-3-O-rutinoside, and rutin exhibited high antioxidant activity and were found in significant amounts in GBL, with concentrations greater than 0.7 mg/g. These results provide an important reference for the development of pharmaceuticals and health products containing GBL.

Efficacy and safety of Ginkgo biloba extract in the treatment of unstable angina pectoris: A systematic review and network meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba is a traditional Chinese medicine extracted from the Ginkgophyta and is commonly used in the treatment of cardiovascular diseases in China. Clinical trials have demonstrated the clinical benefits of Ginkgo biloba extract (GBE) preparations for patients with unstable angina pectoris (UAP).

AIM OF THE STUDY

The efficacy of different GBE preparations in treating UAP may vary, leading to a lack of guidance for physicians when choosing GBE preparations. How to make choices among different GBE preparations is a topic worthy of investigation. In order to clarify the efficacy differences among different GBE preparations, provide a reference for their optimal use conditions, this study was conducted.

MATERIALS AND METHODS

This study included literature from eight databases from inception to November 2023. It included UAP patients, with the control group receiving conventional treatment and the treatment group receiving different GBE preparations in addition to conventional treatment. Angina efficacy, electrocardiogram (ECG) improvement, and frequency of angina were chosen as outcomes. This study employed a systematic review and Bayesian network meta-analysis, and the surface under the cumulative ranking (SUCRA) curve was used for estimating the efficacy ranking.

RESULTS

A total of 98 studies involving 9513 patients and 9 interventions were included. Compared with conventional treatment, GBE preparations combined with conventional treatment had better efficacy in angina symptoms and ECG improvement. According to the SUCRA ranking, Shuxuening injection was most effective in improving angina symptoms and reducing the frequency of angina. Among oral GBE preparations, Ginkgo tablets had the best performance in improving angina symptoms and ECG manifestations, and reducing the frequency of angina. There was no significant difference in the incidence of adverse events between the treatment group and the control group, and all adverse events were mild and self-limiting. Compared with oral preparations, the incidence of adverse events for injections was higher.

CONCLUSIONS

GBE preparations may alleviate angina symptoms and myocardial ischemia in the treatment of UAP with favorable safety. Shuxuening injection may be the most effective among all GBE preparations in improving angina symptoms, while Ginkgo tablets may perform best among oral formulations. The optimal use of GBE injection may be for rapidly alleviating angina symptoms and myocardial ischemia in patients with UAP, and oral formulation of GBE may be more suitable for the long-term treatment of patients with milder symptoms.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022361487, ID: CRD42022361487.

Evolving Strategies for Use of Phytochemicals in Prevention and Long-Term Management of Cardiovascular Diseases (CVD)

This report describes major pathomechanisms of disease in which the dysregulation of host inflammatory processes is a major factor, with cardiovascular disease (CVD) as a primary model, and reviews strategies for countermeasures based on synergistic interaction between various agents, including drugs and generally regarded as safe (GRAS) natural medical material (NMM), such as Ginkgo biloba, spice phytochemicals, and fruit seed flavonoids. The 15 well-defined CVD classes are explored with particular emphasis on the extent to which oxidative stressors and associated ischemia-reperfusion tissue injury contribute to major symptoms. The four major categories of pharmaceutical agents used for the prevention of and therapy for CVD: statins, beta blockers (β-blockers), blood thinners (anticoagulants), and aspirin, are presented along with their adverse effects. Analyses of major cellular and molecular features of drug- and NMM-mediated cardioprotective processes are provided in the context of their development for human clinical application. Future directions of the evolving research described here will be particularly focused on the characterization and manipulation of calcium- and calcineurin-mediated cascades of signaling from cell surface receptors on cardiovascular and immune cells to the nucleus, with the emergence of both protective and pathological epigenetic features that may be modulated by synergistically-acting combinations of drugs and phytochemicals in which phytochemicals interact with cells to promote signaling that reduces the effective dosage and thus (often) toxicity of drugs.

Chinese herbal medicine for the treatment of cardiovascular diseases ─ targeting cardiac ion channels

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality, imposing an increasing global health burden. Cardiac ion channels (voltage-gated Na_V, Ca_V, K_Vs, and others) synergistically shape the cardiac action potential (AP) and control the heartbeat. Dysfunction of these channels, due to genetic mutations, transcriptional or post-translational modifications, may disturb the AP and lead to arrhythmia, a major risk for CVD patients. Although there are five classes of anti-arrhythmic drugs available, they can have varying levels of efficacies and side effects on patients, possibly due to the complex pathogenesis of arrhythmias. As an alternative treatment option, Chinese herbal remedies have shown promise in regulating cardiac ion channels and providing anti-arrhythmic effects. In this review, we first discuss the role of cardiac ion channels in maintaining normal heart function and the pathogenesis of CVD, then summarize the classification of Chinese herbal compounds, and elaborate detailed mechanisms of their efficacy in regulating cardiac ion channels and in alleviating arrhythmia and CVD. We also address current limitations and opportunities for developing new anti-CVD drugs based on Chinese herbal medicines.

Cardioprotective Effect of Rumex vesicarius Linn. Leaf Extract against Catecholamine-Induced Cardiotoxicity

Rumex vesicarius (L.) is a folklore medicinal herb that has been used for centuries to cure cardiovascular diseases. The present work was carefully designed to ascertain the pharmacological basis for R. vesicarius’s therapeutic efficacy in cardiovascular diseases, as well as the underlying mechanism. In the ex vivo investigation, the aqueous-methanolic leaf extract of R. vesicarius was shown to have endothelium-dependent vasorelaxant effects in rabbit aorta tissue preparations, and its hypotensive responses were quantified by pressure and force transducers coupled to the Power Lab Data Acquisition System. Furthermore, when rabbits were subjected to adrenaline-induced myocardial infarction, R. vesicarius demonstrated cardioprotective characteristics. In contrast to the intoxicated group, the myocardial infarction model showed lower ALP, CK-MB, CRP, LDH, ALT, troponin, and AST levels (p > 0.005−0.000), as well as edema, necrosis, apoptosis, inflammatory cell enrolment, and necrosis. R. vesicarius exhibited significant antioxidant activity and delayed noradrenaline-induced platelet aggregation. Its cardioprotective, anticoagulant, and vasorelaxant properties in both investigations (in vivo and ex vivo) are mediated through partial endothelium-dependent, NO and calcium channel blockade mediated vasorelaxation. The minimizing of adrenaline, oxidative stress, and tissue damage demonstrate its therapeutic efficacy in cardiovascular diseases.

Pharmacokinetic, Metabolism, and Metabolomic Strategies Provide Deep Insight Into the Underlying Mechanism of Ginkgo biloba Flavonoids in the Treatment of Cardiovascular Disease

Ginkgo biloba, known as the "living fossil," has a long history of being used as botanical drug for treating cardiovascular diseases and the content of flavonoids as high as 24%. More than 110 different kinds of flavonoids and their derivatives have been separated from G. biloba, including flavones, flavonols, biflavonoids, catechins, and their glycosides, etc., all of which display the ability to dilate blood vessels, regulate blood lipids, and antagonize platelet activating factor, and protect against ischemic damage. At present, many types of preparations based on G. biloba extract or the bioactive flavonoids of it have been developed, which are mostly used for the treatment of cardiovascular diseases. We herein review recent progress in understanding the metabolic regulatory processes and gene regulation of cellular metabolism in cardiovascular diseases of G. biloba flavonoids. First, we present the cardioprotective flavonoids of G. biloba and their possible pharmacological mechanism. Then, it is the pharmacokinetic and liver and gut microbial metabolism pathways that enable the flavonoids to reach the target organ to exert effect that is analyzed. In the end, we review the possible endogenous pathways toward restoring lipid metabolism and energy metabolism as well as detail novel metabolomic methods for probing the cardioprotective effect of flavonoids of G. biloba.

Review: HCN Channels in the Heart

Pacemaker cells are the basis of rhythm in the heart. Cardiovascular diseases, and in particular, arrhythmias are a leading cause of hospital admissions and have been implicated as a cause of sudden death. The prevalence of people with arrhythmias will increase in the next years due to an increase in the ageing population and risk factors. The current therapies are limited, have a lot of side effects, and thus, are not ideal. Pacemaker channels, also called hyperpolarizationactivated cyclic nucleotide-gated (HCN) channels, are the molecular correlate of the hyperpolarization- activated current, called Ih (from hyperpolarization) or If (from funny), that contribute crucially to the pacemaker activity in cardiac nodal cells and impulse generation and transmission in neurons. HCN channels have emerged as interesting targets for the development of drugs, in particular, to lower the heart rate. Nonetheless, their pharmacology is still rather poorly explored in comparison to many other voltage-gated ion channels or ligand-gated ion channels. Ivabradine is the first and currently the only clinically approved compound that specifically targets HCN channels. The therapeutic indication of ivabradine is the symptomatic treatment of chronic stable angina pectoris in patients with coronary artery disease with a normal sinus rhythm. Several other pharmacological agents have been shown to exert an effect on heart rate, although this effect is not always desired. This review is focused on the pacemaking process taking place in the heart and summarizes the current knowledge on HCN channels.

Pharmacological Justification for the Medicinal Use of Plumeria rubra Linn. in Cardiovascular Disorders

Plumeria rubra (L.) is a traditional folkloric medicinal herb used to treat cardiovascular disorders. The present investigation was methodically planned to investigate the pharmacological foundations for the therapeutic effectiveness of P. rubra in cardiovascular illnesses and its underlying mechanisms. Ex vivo vaso-relaxant effects of crude leaf extract of P. rubra were observed in rabbit aorta ring preparations. Hypotensive effects were measured using pressure and force transducers connected to the Power Lab data acquisition system. Furthermore, P. rubra displayed cardioprotective properties in rabbits when they were exposed to adrenaline-induced myocardial infarction. In comparison to the intoxicated group, the myocardial infarction model showed decreased troponin levels, CK-MB, LDH, ALT, ALP, AST, and CRP, as well as necrosis, apoptosis, oedema, and inflammatory cell enrollment. P. rubra has revealed good antioxidant properties and prolonged the noradrenaline intoxicated platelet adhesion. Its anticoagulant, vasorelaxant, and cardioprotective effects in both in vivo and ex vivo investigations are enabled by blocking L-type calcium channels, lowering adrenaline, induced oxidative stress, and tissue tear, justifying its therapeutic utility in cardiovascular disorders.

Jasminum sambac: A Potential Candidate for Drug Development to Cure Cardiovascular Ailments

Jasminum sambac (L.) is a South Asian folkloric medicinal plant that has traditionally been used to treat cardiovascular problems. The current investigation was meticulously organized to explore the pharmacological foundation for the medicinal uses of J. sambac pertaining to cardiovascular ailments and to investigate the core mechanisms. Mechanistic investigation revealed that crude leaf extract of J. sambac produced ex-vivo vasorelaxant effects in endotheliumintact aorta ring preparation and hypotensive effect was recorded via pressure and force transducers coupled to the Power Lab Data Acquisition System. Moreover; J. sambac showed cardioprotective effects against adrenaline -induced left ventricular hypertrophy in rabbits observed hemodynamic. CK-MB, LDH, troponin, CRP, ALT, AST, ALP levels were shown to be lower in the myocardial infarction model, as were necrosis, oedema, and inflammatory cell recruitment in comparison to control. J. sambac has shown good antioxidant potential as well as prolonged the noradrenaline induced platelet adhesion. The vasorelaxant and cardioprotective effects in both in vivo and ex vivo experiments, which are enabled by activation of muscarinic receptor and/or releasing the nitric oxide and by reducing the adrenaline, induced oxidative stress, justifying its usage in cardiovascular disorders.

Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition

Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain cardiovascular homeostasis by coordinating the responses to external and internal environmental stressors. While it is well known that carotid and cardiopulmonary baroreceptors modulate sympathetic vasomotor and parasympathetic cardiac neural autonomic drive, to avoid excessive fluctuations in vascular tone and maintain intravascular volume, there is increasing recognition that baroreceptors also modulate a wide range of non-cardiovascular physiological responses via projections from the nucleus of the solitary tract to regions of the central nervous system, including the spinal cord. These projections regulate pain perception, sleep, consciousness, and cognition. In this article, we summarize the physiology of baroreceptor pathways and responses to baroreceptor activation with an emphasis on the mechanisms influencing cardiovascular function, pain perception, consciousness, and cognition. Understanding baroreceptor-mediated effects on cardiac and extra-cardiac autonomic activities will further our understanding of the pathophysiology of multiple common clinical conditions, such as chronic pain, disorders of consciousness (e.g., abnormalities in sleep-wake), and cognitive impairment, which may result in the identification and implementation of novel treatment modalities. © 2021 American Physiological Society. Compr Physiol 11:1373-1423, 2021.

Effect of Ginkgo biloba extract on pacemaker channels encoded by HCN gene

BACKGROUND

In the present study, the electropharmacological activity of traditional Chinese medicine, Ginkgo biloba extract (GBE), on human hyperpolarization-activated nucleotide-gated (HCN) channels and the underlying "funny" currents was investigated.

METHODS

Standard two-electrode voltage-clamp recordings were employed to examine the properties of cloned HCN subunit currents expressed in Xenopus oocytes under controlled conditions and GBE administration.

RESULTS

We found that GBE irreversibly inhibited the HCN2 and HCN4 channel currents in a concentration-dependent fashion and that the HCN4 current was more sensitive to GBE compared with HCN2. In addition, GBE inhibition of the current amplitudes of HCN2 and HCN4 currents was accompanied by a decrease in the activation and deactivation kinetics.

CONCLUSION

The results of this study contribute toward illustrating the antiarrhythmic mechanism of GBE, which might be useful for the treatment of arrhythmia.

Evaluation of oxidant/antioxidant status in serum of sheep experimentally envenomated with Hemiscorpius lepturus scorpion venom

Scorpion envenomation is a main general health problem in developing countries, especially in tropical and subtropical regions. Hemiscorpius lepturus as a member of the Hemiscorpiidae family is cause of the most scorpion sting lethality in Iran. In the present study, the oxidative stress and antioxidant defense in serum of envenomated sheep with the venom of Hemiscorpius lepturus were investigated. Nine sheep were randomly divided into three groups (three in each). Groups A, B and C received 0.10, 0.05 and 0.01 mg kg-1 of H. lepturus venom subcutaneously, respectively. Blood sampling were performed 30 min before envenomation (control) and 30 min, 1, 2, 3 and 6 hr after envenomation and serum levels of total antioxidant capacity (TAC), malonedialdehyde (MDA) and protein carbonyl (PCO) were determined. The TAC was significantly increased at the doses of 0.10 mg kg-1 (at 3 hr) and 0.05 mg kg-1 (at 6 hr) compared to pre-injection time. However, no significant differences were observed in serum levels of MDA and PCO in different groups. It can be concluded that the dose of 0.01 mg kg-1 of venom had no effect on stress factors of serum, but according to increased level of TAC at the doses of 0.05 and 0.10 and no significant changes in serum levels of MDA and PCO, the oxidative damage has been prevented by the antioxidant defense system response.

Cardioprotective Action of Ginkgo biloba Extract against Sustained β-Adrenergic Stimulation Occurs via Activation of M2/NO Pathway

Ginkgo biloba is the most popular phytotherapic agent used worldwide for treatment of several human disorders. However, the mechanisms involved in the protective actions of Ginkgo biloba on cardiovascular diseases remain poorly elucidated. Taking into account recent studies showing beneficial actions of cholinergic signaling in the heart and the cholinergic hypothesis of Ginkgo biloba-mediated neuroprotection, we aimed to investigate whether Ginkgo biloba extract (GBE) promotes cardioprotection via activation of cholinergic signaling in a model of isoproterenol-induced cardiac hypertrophy. Here, we show that GBE treatment (100 mg/kg/day for 8 days, v.o.) reestablished the autonomic imbalance and baroreflex dysfunction caused by chronic β-adrenergic receptor stimulation (β-AR, 4.5 mg/kg/day for 8 days, i.p.). Moreover, GBE prevented the upregulation of muscarinic receptors (M₂) and downregulation of β₁-AR in isoproterenol treated-hearts. Additionally, we demonstrated that GBE prevents the impaired endothelial nitric oxide synthase activity in the heart. GBE also prevented the pathological cardiac remodeling, electrocardiographic changes and impaired left ventricular contractility that are typical of cardiac hypertrophy. To further investigate the mechanisms involved in GBE cardioprotection in vivo, we performed in vitro studies. By using neonatal cardiomyocyte culture we demonstrated that the antihypertrophic action of GBE was fully abolished by muscarinic receptor antagonist or NOS inhibition. Altogether, our data support the notion that antihypertrophic effect of GBE occurs via activation of M₂/NO pathway uncovering a new mechanism involved in the cardioprotective action of Ginkgo biloba.

The Role of Biologically Active Ingredients from Natural Drug Treatments for Arrhythmias in Different Mechanisms

Arrhythmia is a disease that is caused by abnormal electrical activity in the heart rate or rhythm. It is the major cause of cardiovascular morbidity and mortality. Although several antiarrhythmic drugs have been used in clinic for decades, their application is often limited by their adverse effects. As a result, natural drugs, which have fewer side effects, are now being used to treat arrhythmias. We searched for all articles on the role of biologically active ingredients from natural drug treatments for arrhythmias in different mechanisms in PubMed. This study reviews 19 natural drug therapies, with 18 active ingredient therapies, such as alkaloids, flavonoids, saponins, quinones, and terpenes, and two kinds of traditional Chinese medicine compound (Wenxin-Keli and Shensongyangxin), all of which have been studied and reported as having antiarrhythmic effects. The primary focus is the proposed antiarrhythmic mechanism of each natural drug agent. Conclusion. We stress persistent vigilance on the part of the provider in discussing the use of natural drug agents to provide a solid theoretical foundation for further research on antiarrhythmia drugs.

Role of gap junction involved with endothelium-derived hyperpolarizing factor for the quercetin-induced vasodilatation in rat mesenteric artery

AIMS

Modulation of vasodilating actions by quercetin, a kind of flavonoid, was investigated using rat mesenteric arterial ring strips.

MAIN METHODS

Ring strips (1mm) of rat mesenteric artery were used. The specimens were kept at 36.5 °C in Krebs-Henseleit solution oxygenated with 95% O(2) and 5% CO(2).

KEY FINDINGS

Quercetin (0.1 to 100 μM) dilated the contraction induced by norepinephrine (1 μM) in a concentration-dependent manner. The quercetin-induced vasodilatation was almost resistant to both 100 μM L-N(G)-nitro arginine methyl ester (L-NAME) and 100 μM indomethacin. At 1mM tetraethylammonium (a KCa channel inhibitor) decreased the quercetin-induced vasodilatation, which was resistant to L-NAME and indomethacin, but not significantly. L-NAME- and indomethacin-resistant quercetin-induced vasodilatation was significantly attenuated by 100 μM 18α- and 50 μM 18β-glycyrrhetinic acids (gap junction inhibitors). Endothelium removal as well significantly attenuated the vasodilatation to the same extent.

SIGNIFICANCE

These results indicate that quercetin dilates the mesenteric artery via endothelium-dependent mechanisms, and the dilatation is mainly mediated by gap junctions closely involved with endothelium-derived hyperpolarizing factor (EDHF).

Influence of ethanol extract of Ginkgo biloba leaves on the isolated rat heart work and mitochondria functions

In this study, we attempted to elucidate whether the effects of ethanol extract of Ginkgo biloba leaves (GBE) observed previously on isolated rat heart mitochondria may be realized in situ (in case of isolated heart perfused under normal conditions and under ischemia-reperfusion). We found that GBE at low concentrations (0.01, 0.05, and 0.1 μL/mL) does not affect the heart rate and parameters of electrocardiogram (ECG) but produces a small increase in the coronary flow. Higher concentration of GBE (0.2 and 0.3 μL/mL) diminished the heart rate, decreased the coronary flow, and tended to enhance the parameters of ECG. The contractility of isolated rat heart and mitochondrial nicotinamide adenine dinucleotide reduced form fluorescence decreased in a GBE concentration-dependent manner. Mitochondria isolated from hearts pre-perfused with GBE (0.05 μL/mL) for 20 minutes before nonflow global ischemia-reperfusion (45 min/15 min) showed higher respiratory rates with pyruvate + malate in state 2 and state 3, higher respiratory control index, and diminished H₂O₂ generation compared with untreated group. Higher GBE concentration, 0.4 μL/mL, had no effect on H2O2 generation and did not prevent the ischemia-reperfusion-induced decrease of pyruvate + malate oxidation in state 3 but even enhanced it. However, in the case of nonischemic perfusions, this GBE concentration had no significant effect on these parameters of respiratory functions of isolated heart mitochondria.

Herbal remedies, mood, and cognition

Herbal medicines were the "sole" source of medicine for thousands of years, in every culture since the advent of human civilization. Today, patients are increasing the use of these botanicals for numerous conditions, such as mood and cognition. This article will explore commonly used herbal remedies for mood and cognition functioning. It is imperative that nurses and nurse practitioners obtain expertise with these botanicals with regard to efficacy, adverse effects and contraindications, possible drug interactions, and safety considerations.

Cardiovascular ion channels as a molecular target of flavonoids

Flavonoids are a class of naturally occurring polyphenols abundant in edibles and beverages of plant origin. Epidemiological studies consistently associate high flavonoid intake with a reduced risk for the development of cardiovascular diseases. So far these beneficial effects have been mainly attributed to nonspecific antioxidant and antiinflammatory properties. However, there is an increasing body of evidence that flavonoids specifically target molecular structures including cardiovascular ion channels. Playing a pivotal role in the regulation of vascular tone and cardiac electric activity, ion channels represent a major target for the induction of antihypertensive and cardioprotective effects. Thus, pharmacological properties of flavonoids on cardiovascular ion channels, ion currents and tissue preparations are being increasingly addressed in experimental studies. Whereas it has become clear that cardiovascular ion channels represent an important molecular target of flavonoids, the published data have not yet been systematically reviewed.

Possible Involvement of Ca Activated K Channels, SK Channel, in the Quercetin-Induced Vasodilatation

Effects of quercetin, a kind of flavonoids, on the vasodilating actions were investigated. Among the mechanisms for quercetin-induced vasodilatation in rat aorta, the involvement with the Ca(2+) activated K(+) (K(Ca)) channel was examined. Pretreatment with NE (5 microM) or KCl (60 mM) was carried out and then, the modulation by quercetin of the constriction was examined using rat aorta ring strips (3 mm) at 36.5. Quercetin (0.1 to 100 microM) relaxed the NE-induced vasoconstrictions in a concentration-dependent manner. NO synthesis (NOS) inhibitor, NG-monomethyl-L-arginine acetate (L-NMMA), at 100 microM reduced the quercetin (100 microM)-induced vasodilatation from 97.8+/-3.7% (n=10) to 78.0+/-11.6% (n=5, p<0.05). Another NOS inhibitor, L-NG-nitro arginine methyl ester (L-NAME), at 100 microM also had the similar effect. In the presence of both 100 microM L-NMMA and 10 microM indomethacin, the quercetin-induced vasodilatation was further attenuated by 100 microM tetraethylammonium (TEA, a K(Ca) channel inhibitor). Also TEA decreased the quercetin-induced vasodilatation in endothelium-denuded rat aorta. Used other K(Ca) channel inhibitors, the quercetin-induced vasodilatation was attenuated by 0.3 microM apamin (a SK channel inhibitor), but not by 30 nM charybdotoxin (a BK and IK channel inhibitor). Quercetin caused a concentration-dependent vasodilatation, due to the endothelium-dependent and -independent actions. Also quercetin contributes to the vasodilatation selectively with SK channel on smooth muscle.

Ginkgo biloba extract improves coronary artery circulation in patients with coronary artery disease: contribution of plasma nitric oxide and endothelin-1

In patients with coronary artery disease (CAD), coronary blood flow is usually impaired due to imbalanced vasoactive substances such as nitric oxide (NO) and endothelin-1 (ET-1). The study was designed to test the effects of Ginkgo biloba extract (GBE) on the distal left anterior descending coronary artery (LAD) blood flow and plasma NO and ET-1 levels. Eighty CAD patients were randomly assigned to GBE (n = 42) and control (n = 38) groups. The LAD blood flow was assessed non-invasively using Doppler echocardiography at baseline and after 2 weeks. GBE treatment demonstrated a significant improvement in maximal diastolic peak velocity (MDPV), maximal systolic peak velocity (MSPV) and diastolic time velocity integral (DTVI) compared with controls (14.61 +/- 4.51% vs 0.67 +/- 2.66%, 9.03 +/- 4.81% vs 0.34 +/- 2.67% and 14.69 +/- 5.08% vs 0.68 +/- 3.00%, respectively, p < 0.01). NO was increased by 12.42% (p < 0.01), whereas ET-1 was decreased by 5.82% (p < 0.01). The NO/ET-1 ratio was increased by 19.47% (p < 0.01). A linear correlation was confirmed between the percentage change in LAD blood flow and in NO, ET-1 or NO/ET-1 ratio following GBE treatment. The results suggest that GBE treatment in CAD patients led to an increase of LAD blood flow, which might at least be related partly to the restoration of the delicate equilibrium between NO and ET-1.

Protective effects of Ginkgo biloba extract against mercury(II)-induced cardiovascular oxidative damage in rats

This study was designed to determine the possible protective effect of Ginkgo biloba extract (EGb) against Hg II-induced oxidative damage and also thromboplastic activity in the aorta and heart tissues. Wistar albino rats of either sex (200-250 g) were divided into four groups. Rats were injected intraperitoneally with (1) control (C) group: 0.9% NaCl; (2) EGb group: Ginkgo biloba extract (Abdi Ibrahim Pharmaceutical Company, Istanbul, Turkey) at a dose of 50 mg/kg/day; (3) Hg group: a single dose of 5 mg/kg mercuric chloride (HgCl(2)); and (4) Hg + EGb group: First day EGb at a dose of 50 mg/kg/day, i.p., 1 hour after HgCl(2) (5 mg/kg) injection; following four days EGb at a dose 50 mg/kg/day, i.p. After decapitation of the rats, trunk blood was obtained and serum tumor necrosis factor-alpha (TNF-alpha), lactate dehydrogenase (LDH) activity, and malondialdehyde (MDA) and glutathione (GSH) levels were analysed. In the aorta and heart tissues total protein, MDA, GSH levels and thromboplastic activity were determined. The results revealed that HgCl(2) induced oxidative tissue damage, as evidenced by increases in MDA levels and decreased GSH levels both in serum and tissue samples. Thromboplastic activity was increased significantly following Hg administration, which verifies the cardiotoxic effects of HgCl(2). Serum LDH and TNF-alpha were elevated in the Hg group compared with the control group. Since EGb treatment reversed these responses, it seems likely that Ginkgo biloba extract can protect the cardiovascular tissues against HgCl(2)-induced oxidative damage.

Inhibitory effects of Ginkgo biloba leaf flavonoids on proliferation of human gastric cancer cell line BGC823 in vitro

AIM: To extract the flavonoids from Ginkgo biloba leaf, and to investigate its inhibitroy effects on the proliferation of human gastric cancer cell line BGC823 cultured in vitro.

METHODS: Ethanol (700 mL/L) was used to extract the flavonoids from the leaf of Ginkgo biloba. Three wavelength spectrophotometry was used to determine the content of flavonoids in the extracts. Human gastric cancer cells BGC823 cultured in vitro were treated with different concentrations of the flavonoids, and then the proliferation of the cells was detected by MTT assay and flow cytometry.

RESULTS: The content of flavonoids in the extracts was 140 mg/g. The flavonoids from Ginkgo biloba leaf inhibited the proliferation of BGC823 cells in a dose-dependent manner. The rate of cells in S phase was notably increased as compared with that in the controls (42.17±0.50% vs 32.13±0.45%, P = 0.001), and the apoptotic rate of the cells was also increased (4.10±0.03% vs 2.21±0.01%, P = 0.002).

CONCLUSION: Ginkgo biloba leaf flavonoids can inhibit the proliferation of human gastric cancer cell line BGC823 by affecting the cycle the cells.

Suppression of pacemaker activity by Ginkgo biloba extract and its main constituent, bilobalide in rat sino-atrial nodal cells

Effects of Ginkgo biloba extract (GBE) and bilobalide (a main constituent) on the pacemaker activity and the underlying ionic currents in rat sino-atrial (SA) nodal cells were investigated using patch-clamp techniques. Both GBE and bilobalide depressed the pacemaker activity in a concentration-dependent manner. At both 0.03 mg/ml GBE and 0.3 microM bilobalide, a negative chronotropic effect was produced. Dysrhythmias often occurred. The L-type Ca(2+) current (I(Ca)) and the hyperpolarization-activated inward current (I(f)) decreased by 69.7+/-3.2% (n=6, P<0.001) and by 12.6+/-2.1% (n=7, P<0.05) at 0.03 mg/ml GBE, and by 51.2+/-3.3% (n=6, P<0.01) and by 19.8+/-2.2 % (n=6, P<0.05) at 0.3 microM bilobalide, respectively. The delayed rectifier K(+) current (I(K)) also decreased. The inhibition was 12.3+/-2.0% (n=6, P<0.05) at 0.03 mg/ml GBE, and was 28.0+/-2.9% (n=6, P<0.05) at 0.3 microM bilobalide. These results indicate that cardiac ionic channels contributing to the pacemaking are highly sensitive to GBE and bilobalide, which can sufficiently modify the spontaneous activity in rat SA nodal cells.

Age-related changes in the vasodilating actions of Ginkgo biloba extract and its main constituent, bilobalide, in rat aorta

BACKGROUND

Age-related modulation in vasodilating actions induced by Ginkgo biloba extract (GBE) and bilobalide, a main constituent of GBE, were examined using rat aorta ring strips.

METHODS

Wistar rats from 5 to 25 weeks old were used, and the isolated aorta ring strips were fixed in Krebs-Henseleit solution.

RESULTS

GBE and bilobalide concentration-dependently dilated norepinephrine (NE)-induced vasoconstriction in all aged rats. The vasodilating actions generally decreased in accordance with aging. GBE at 1 mg/ml decreased from 28.4+/-3.8% (n=5) in 5-week-old rats to 23.7+/-7.1 (n=7) in 25-week-old rats, but not significantly. GBE (3 mg/ml)-induced vasodilation was maximum by 73.7+/-2.1% (n=4, P<0.001) in 10-week-old rats. GBE had the marked vasodilation at younger ages and further decreased it with developing ages. In the rats older than 20 weeks, however, GBE tended to rather increase the strength of vasodilating action. On the other hand, the vasorelaxation induced by 30 micromol/l bilobalide significantly decreased from 11.8+/-1.4% (n=4) in 5-week-old rats to 2.3+/-1.5% (n=5, P<0.01) in 25-week-old rats, and by 100 micromol/l from 20.2+/-3.4% (n=4) to 5.6+/-2.5% (n=5, P<0.01), respectively. Bilobalide had the similar age-related actions. The age-dependent attenuation was produced milder by bilobalide than by GBE. At lower concentrations, however, bilobalide caused the weak vasocontriction in 20- and 25-week-old rats.

CONCLUSION

GBE and bilobalide possess a similar characteristic for age-related modification, clinically suggesting the more effective actions of GBE for elder persons.

Effects of ginkgo biloba extract on cation currents in rat ventricular myocytes

Ginkgo biloba extract (GBE), a valuable natural product for cerebral and cardiovascular diseases, is mainly composed of two classes of constituents: terpene lactones (e.g., ginkgolide A and B, bilobalide) and flavone glycosides (e.g., quercetin and kaempferol). Its electrophysiological action in heart is yet unclear. In the present study, using whole-cell patch clamp technique, we investigated electrophysiological effects of GBE on cation channel currents in ventricular myocytes isolated from rat hearts. We found that GBE 0.01-0.1% inhibited significantly the sodium current (I(Na)), L-type calcium current (I(Ca)) and transient outward potassium current (IK(to)) in a concentration-dependent manner. Surprisingly, its main ingredients, ginkgolide A (GB A), ginkgolide B (GB B) and bilobalide (GB BA) at 0.1 mM did not exhibit any significant effect on these cation channel currents. These results suggested that GBE is a potent non-selective cation channel modulator in cardiaomyocytes. Other constituents (rather than GB A, GB B and GB BA) might be responsible for the observed inhibitory effects of GBE on cation channels.