Effects of inhibition of calcium and potassium currents in guinea-pig cardiac contraction: comparison of beta-caryophyllene oxide, eugenol, and nifedipine

Cardiotoxicity Assessment through a Polymer-Based Cantilever Platform: An Integrated Electro-Mechanical Screening Approach

Preclinical drug screening for cardiac toxicity has traditionally relied on observing changes in cardiomyocytes' electrical activity, primarily through invasive patch clamp techniques or non-invasive microelectrode arrays (MEA). However, relying solely on field potential duration (FPD) measurements for electrophysiological assessment can miss the full spectrum of drug-induced toxicity, as different drugs affect cardiomyocytes through various mechanisms. A more comprehensive approach, combining field potential and contractility measurements, is essential for accurate toxicity profiling, particularly for drugs targeting contractile proteins without affecting electrophysiology. However, previously proposed platform has significant limitations in terms of simultaneous measurement. The novel platform addresses these issues, offering enhanced, non-invasive evaluation of drug-induced cardiotoxicity. It features eight cantilevers with patterned strain sensors and MEA, enabling real-time monitoring of both cardiomyocyte contraction force and field potential. This system can detect minimum cardiac contraction force of ≈2 µN and field potential signals with 50 µm MEA diameter, using the same cardiomyocytes in measurements of two parameters. Testing with six drugs of varied mechanisms of action, the platform successfully identifies these mechanisms and accurately assesses toxicity profiles, including drugs not inhibiting potassium channels. This innovative approach presents a comprehensive, non-invasive method for cardiac function assessment, poised to revolutionize preclinical cardiotoxicity screening.

Targeting cardiovascular risk factors with eugenol: an anti-inflammatory perspective

Inflammation is a multifaceted biological reaction to a wide range of stimuli, and it has been linked to the onset and progression of chronic diseases such as heart disease, cancer, and diabetes. Inflammatory markers found in the blood, including C-reactive protein, serum amyloid A, fibrinogen, plasma viscosity, erythrocyte sedimentation rate, interleukin-6, and soluble adhesion molecules (like intercellular adhesion molecule-1 and vascular cell adhesion molecule-1), are risk factors for cardiovascular diseases such as coronary heart disease, stroke, and peripheral arterial disease. These markers play a crucial role in understanding and assessing cardiovascular health. Due to this complicated relationship between inflammation and cardiovascular disease, anti-inflammatory agents of natural origin have been the subject of many preclinical and clinical studies in recent years. Eugenol is a natural phenolic compound found in clove oil, nutmeg oil, cinnamon oil, and bay leaf oil, as well as other essential oils. Eugenol has been shown to have anti-inflammatory properties in many forms of experimental inflammation. It may scavenge free radicals, which contribute to inflammation and tissue damage. Various studies also suggest that eugenol can limit the production of inflammatory mediators such as prostaglandins, cytokines, and chemokines. Animal models of arthritis, colitis, and lung damage, as well as human clinical studies, have shown that eugenol has phenomenal anti-inflammatory properties. These properties suggest that eugenol may be able to reduce the risk of cardiovascular diseases.

Eugenol delays the onset of ouabain-induced ventricular cardiac arrhythmias in guinea pigs

Eugenol is an aromatic compound used in the manufacture of medicines, perfumes, cosmetics and as an anaesthetic due to the ability of the drug to block the neuronal isoform of voltage-gated Na+ channels (NaV ). Some arrhythmias are associated with gain of function in the sodium current (INa ) found in cardiomyocytes, and antiarrhythmic sodium channel blockers are commonly used in the clinical practice. This study sought to elucidate the potential mechanisms of eugenol's protection in the arrhythmic model of ouabain-induced arrhythmias in guinea pig heart. Ex vivo arrhythmias were induced using 50 μM of ouabain. The antiarrhythmic properties of eugenol were evaluated in the ex vivo heart preparation and isolated ventricular cardiomyocytes. The compound's effects on cardiac sodium current and action potential using the patch-clamp technique were evaluated. In all, eugenol decreased the ex vivo cardiac arrhythmias induced by ouabain. Furthermore, eugenol showed concentration dependent effect upon peak INa , left-shifted the stationary inactivation curve and delayed the recovery from inactivation of the INa . All these aspects are considered to be antiarrhythmic. Our findings demonstrate that eugenol has antiarrhythmic activity, which may be partially explained by the ability of eugenol to change de biophysical properties of INa of cardiomyocytes.

Aromatic Plant-Based Functional Foods: A Natural Approach to Manage Cardiovascular Diseases

Aromatic plants and their essential oils have shown beneficial effects on the cardiovascular system and, therefore, are potential raw materials in the development of functional foods. However, despite their undeniable potential, essential oils present several limitations that need to be addressed, such as stability, poor solubility, undesirable sensory effects, and low bioavailability. The present review provides a current state-of-the-art on the effects of volatile extracts obtained from aromatic plants on the cardiovascular system and focuses on major challenges that need to be addressed to increase their use in food products. Moreover, strategies underway to overcome these limitations are pointed out, thus anticipating a great appreciation of these extracts in the functional food industry.

Cardiovascular Harmful Effects of Recommended Daily Doses (13 µg/kg/day), Tolerable Upper Intake Doses (0.14 mg/kg/day) and Twice the Tolerable Doses (0.28 mg/kg/day) of Copper

Copper is essential for homeostasis and regulation of body functions, but in excess, it is a cardiovascular risk factor since it increases oxidative stress. The objective of this study was to evaluate the effects of exposure to the recommended daily dose (13 µg/kg/day), upper tolerable dose (0.14 mg/kg/day) and twice the upper tolerable dose (0.28 mg/kg/day) via i.p. over 4 weeks on the vascular reactivity of aortic rings and the contraction of LV papillary muscles of male Wistar rats. It was also determined whether the antioxidant peptide from egg white hydrolysate (EWH) prevents these effects. Copper exposure at the doses evaluated did not change weight gain of male Wistar rats, the reactivity of the aortic rings or the cardiac mass. The dose of 0.13 µg/kg/day did not reduce the force of contraction, but it impaired the time derivatives of force. Doses of 0.14 and 0.28 mg/kg/day reduced the force of contraction, the inotropic response to calcium and isoproterenol, the postrest contraction and the peak and plateau of tetanized contractions. EWH treatment antagonized these effects. These results suggest that copper, even at the dose described as upper tolerable, can impair cardiac contraction without altering vascular reactivity. Antioxidative stress therapy with EWH reversed these harmful effects, suggesting a possible strategy for the amelioration of these effects.

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.

[Impact of essential oil vapors inhalation on blood pressure in patients with hypertension]

Increase of patients with hypertension in the world determines the search for new, accessible, easily applicable and mildly effective antihypertensive agents, particularly essential oils (EO). Currently available studies of the EO impact on blood pressure do not allow to assess the efficiency of such therapy.

OBJECTIVE

To perform the comparative study of antihypertensive effects of inhalation with EO vapors of various composition.

MATERIAL AND METHODS

The investigation included 849 women aged 55-89 years with hypertension. Two examination series were done: 10- and 20-minute duration procedures. Trial subjects were divided into control (psychorelaxation procedure) and experimental (psychorelaxation procedure combined with the EO inhalation of common basil, Italian immortelle, clove tree, common hyssop, cardamom, coriander, Caucasian nepeta, nepeta cataria, spicate lavender, bay laurel, the sort «Oxamitov» of brook-mint, the sorts «Prilutskaya», «Udaichanka», «Ukrainian» of pepper mint, the Siberian fir, Tauric wormwood, the sort «Crimean red» of rose, rosmarinus officinalis, Scotch pine, fennel, mountain savory, garden savory and clary sage; EO concentration in air - 1 mg/m³) groups. Systolic and diastolic blood pressure, heart rate were measured, as well as the coefficient of blood circulation efficiency and Robinson index were calculated before and after the examination in trial subjects.

RESULTS

It has been established that the EO of clary sage, bay laurel, Caucasian nepeta and the sort «Oxamitov» of brook-mint have antihypertensive action at both 10-minute and 20-minute exposure. The antihypertensive action of EO of common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis, garden savory was found after 10-minute exposure. There was no antihypertensive action in EO application of Italian immortelle, common hyssop, spicate lavender, the sorts «Prilutskaya», «Ukrainian», «Udaichanka» of pepper mint, Siberian fir, tauric wormwood, Scotch pine and fennel.

CONCLUSION

The EO vapors' inhalation of clary sage, bay laurel, Caucasian nepeta, the sort «Oxamitov» of brook-mint, common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis and garden savory can be a promising method to reduce blood pressure in patients with hypertension.

Downregulation of CYP17A1 by 20-hydroxyecdysone: plasma progesterone and its vasodilatory properties

Aim: To investigate the effect of 20-hydroxyecdysone on steroidogenic pathway genes and plasma progesterone, and its potential impact on vascular functions. Methods: Chimeric mice with humanized liver were treated with 20-hydroxyecdysone for 3 days, and hepatic steroidogenic pathway genes and plasma progesterone were measured by transcriptomics and GC–MS/MS, respectively. Direct effects on muscle and mesenteric arterioles were assessed by myography. Results: CYP17A1 was downregulated in 20-hydroxyecdysone-treated mice compared with untreated group (p = 0.04), with an insignificant increase in plasma progesterone. Progesterone caused vasorelaxation which was blocked by 60 mM KCl, but unaffected by nitric oxide synthase inhibition. Conclusion: In the short term, 20-hydroxyecdysone mediates CYP17A1 downregulation without a significant increase in plasma progesterone, which has a vasodilatory effect involving inhibition of voltage-dependent calcium channels, and the potential to enhance 20-hydroxyecdysone vasorelaxation.

Copper exposure for 30 days at a daily dose twice the recommended increases blood pressure and cardiac contractility

Copper is an essential factor for the body's homeostasis. However, excess copper compromises organic functions.

AIMS

We investigated the effects of copper exposure for 30 days on blood pressure (BP) and cardiac contractility and the putative involvement of nitric oxide (NO) and reactive oxygen species.

MAIN METHODS

Wistar rats (12 weeks old, 280 g) were randomized to the treated group that was exposed for 30 days to copper (2000 μg/kg/day CuCl₂) and the control (Ct) group that received intraperitoneal saline (0.9%).

KEY FINDINGS

The blood concentration of copper was ~1.26 μg/mL in the copper-exposed group and ~0.024 μg/mL in the Ct group. The main metal accumulations occurred in the liver and kidneys. Copper exposure increased systolic BP (Cu: 141 ± 3 mmHg; Ct: 133 ± 3 mmHg) (tail cuff method), left ventricular systolic pressure and papillary muscle force. Calcium release from the sarcoplasmic reticulum was reduced. The contractile response to Ca²⁺ was increased by copper, and the effect was not altered by L-NAME. Copper increased contractions dependent on sarcolemmal Ca²⁺ influx, and this effect was not altered by L-NAME. The percentage response to isoproterenol decreased in the copper-exposed group, but L-NAME did not alter this reduction. Papillary force development at the peak and plateau of tetanic contractions also increased after copper exposure, but this effect was not altered by L-NAME. In situ detection of OH local production increased.

SIGNIFICANCE

Copper increased BP and cardiac force, increased Ca²⁺ inflow, reduced Ca²⁺ reuptake by the sarcoplasmic reticulum, and increased OH local production. Copper exposure at doses considered tolerable affects cardiac contractility.

Pharmacological Properties and Health Benefits of Eugenol: A Comprehensive Review

The biologically active phytochemicals are sourced from edible and medicinally important plants and are important molecules being used for the formulation of thousands of drugs. These phytochemicals have great benefits against many ailments particularly the inflammatory diseases or oxidative stress-mediated chronic diseases. Eugenol (EUG) is a versatile naturally occurring molecule as phenolic monoterpenoid and frequently found in essential oils in a wide range of plant species. EUG bears huge industrial applications particularly in pharmaceutics, dentistry, flavoring of foods, agriculture, and cosmeceutics. It is being focused recently due to its great potential in preventing several chronic conditions. The World Health Organization (WHO) has declared EUG as a nonmutant and generally recognized as safe (GRAS) molecule. The available literature about pharmacological activities of EUG shows remarkable anti-inflammatory, antioxidant, analgesic, and antimicrobial properties and has a significant effect on human health. The current manuscript summarizes the pharmacological characteristics of EUG and its potential health benefits.

Crosstalk between AdipoR1/AdipoR2 and Nrf2/HO-1 signal pathways activated by β-caryophyllene suppressed the compound 48/80 induced pseudo-allergic reactions

Mast cell activation is initiated by two signaling pathways: Immunoglobulin E (IgE) dependent and IgE independent pathway. It is reported that the IgE-independent type or pseudo-allergy pathway gets activated by G-protein-dependent activation of the mast cell. Recently, adiponectin (APN) receptors, AdipoR1, and AdipoR2 are identified as G-protein-coupled receptors (GPCRs). Interestingly, APN replenishment is reported to activate the Nrf2/HO-1 signaling axis. However, no study has been performed interlinking the role of APN and Nrf2/HO-1 signaling axis in pseudo-allergic reaction. In the present study, we evaluated the anti-pseudo-allergic effects of β-caryophyllene, an FDA approved food additive, in activating AdipoR1/AdipoR2 and Nrf2/HO-1 axis signaling pathway. Compound 48/80 (C48/80) induced systemic and cutaneous anaphylaxis-like shock in BALB/c mice was performed to assess the efficacy of BCP. To assess the effect of BCP in anaphylactic hypotension, mean arterial pressure was measured in Wistar rats. Inhibitory properties of BCP in mast cell degranulation were estimated in rat peritoneal mast cells (RPMCs). ELISA was performed to estimate IL-6, TNF, IL-1β, IgE, OVA-IgE and APN and western blotting for protein expression of Nrf2/HO-1 and AdipoR1-AdipoR2. BCP dose-dependently inhibited systemic and cutaneous anaphylaxis-like shock induced by C48/80. BCP dose-dependently inhibited the mast cell degranulation followed by inhibition of histamine release as well as BCP dose-dependently activated the Nrf2/HO-1 and AdipoR1-AdipoR2 signaling axis pathway. Moreover, BCP reverses the drop-in blood pressure when the hemodynamic parameters were accessed. Our findings suggest that BCP is a potent AdipoR1/AdipoR2-Nrf2/HO-1 axis pathway agonist that may suppress the IgE-independent pathway towards allergic response to secretagogues.

Eugenol interacts with cardiac sodium channel and reduces heart excitability and arrhythmias

AIMS

Eugenol is a natural compound found in the essential oils of many aromatic plants. The compound is used as a local anesthetic because of its inhibitory effect on the voltage-gated Na⁺ channels (Na_v), which are expressed in the nociceptive neurons. Eugenol has shown wide range of activities in the cardiovascular system; most of these activities are attributed to the modulation of voltage-sensitive Ca²⁺ channels. However, its action on Na_v1.5, the main subtype of Na_v expressed in the mammalian myocardium, is unknown. The interaction of eugenol with Na_v1.5 could also contribute to its antiarrhythmic properties in vitro and ex vivo. We investigated the compound's effect on sodium current (I_Na) and its possible cardiac antiarrhythmic activity.

METHODS

The effect of eugenol on cardiac contractility was investigated using isolated atrium from guinea pig (for isometric force measurements). The compound's effect on I_Na was evaluated using human embryonic cell transiently expressing human Nav1.5 and patch-clamp technique.

KEY FINDINGS

Eugenol caused negative inotropic and chronotropic effects in the atria. In the ex vivo arrhythmia model, eugenol decreased atrial pacing disturbance induced by ouabain. Eugenol reduced the I_Na in a concentration-dependent manner. Furthermore, the compound left-shifted the stationary inactivation curve, delayed recovery from inactivation of the I_Na, and preferentially blocked the channel in the inactivated state. Importantly, eugenol was able to attenuate the late sodium current. All these aspects are considered to be antiarrhythmic.

SIGNIFICANCE

Overall, our findings demonstrate that eugenol has antiarrhythmic activity due, at least in part, to its interaction with Na_v1.5.

The Role of Essential Oils and Their Main Compounds in the Management of Cardiovascular Disease Risk Factors

Cardiovascular diseases (CVDs) are a global health burden that greatly impact patient quality of life and account for a huge number of deaths worldwide. Despite current therapies, several side effects have been reported that compromise patient adherence; thus, affecting therapeutic benefits. In this context, plant metabolites, namely volatile extracts and compounds, have emerged as promising therapeutic agents. Indeed, these compounds, in addition to having beneficial bioactivities, are generally more amenable and present less side effects, allowing better patient tolerance. The present review is an updated compilation of the studies carried out in the last 20 years on the beneficial potential of essential oils, and their compounds, against major risk factors of CVDs. Overall, these metabolites show beneficial potential through a direct effect on these risk factors, namely hypertension, dyslipidemia and diabetes, or by acting on related targets, or exerting general cellular protection. In general, monoterpenic compounds are the most studied regarding hypotensive and anti-dyslipidemic/antidiabetic properties, whereas phenylpropanoids are very effective at avoiding platelet aggregation. Despite the number of studies performed, clinical trials are sparse and several aspects related to essential oil’s features, namely volatility and chemical variability, need to be considered in order to guarantee their efficacy in a clinical setting.

Cardiodepressive Effect of Eugenyl Acetate in Rodent Heart

No presente trabalho investigou-se o efeito inotrópico do acetato de eugenil (AE), bem como sua ação sobre a corrente de Ca²⁺ do tipo L (I_Ca,L). Os experimentos de contratilidade foram realizados em átrio esquerdo isolado de cobaia exposto às concentrações crescentes da droga (1 a 5.000μM). O AE reduziu a força de contração atrial (IC₅₀=558±24,06μM) de modo dependente de concentração. O efeito do AE sobre a I_Ca,L também foi avaliado em cardiomiócitos ventriculares isolados de camundongos, utilizando-se a técnica de “patch-clamp”. O AE apresentou um efeito inibitório (IC₅₀=1.337±221μM) sobre os canais de Ca²⁺ sensíveis à voltagem (Ca_V1.2). Em conclusão, o AE apesenta efeito cardiodepressor que se deve, pelo menos em parte, à diminuição da entrada de Ca²⁺ nos cardiomiócitos.

Medicinal properties of terpenes found in Cannabis sativa and Humulus lupulus

Cannabaceae plants Cannabis sativa L. and Humulus lupulus L. are rich in terpenes - both are typically comprised of terpenes as up to 3-5% of the dry-mass of the female inflorescence. Terpenes of cannabis and hops are typically simple mono- and sesquiterpenes derived from two and three isoprene units, respectively. Some terpenes are relatively well known for their potential in biomedicine and have been used in traditional medicine for centuries, while others are yet to be studied in detail. The current, comprehensive review presents terpenes found in cannabis and hops. Terpenes' medicinal properties are supported by numerous in vitro, animal and clinical trials and show anti-inflammatory, antioxidant, analgesic, anticonvulsive, antidepressant, anxiolytic, anticancer, antitumor, neuroprotective, anti-mutagenic, anti-allergic, antibiotic and anti-diabetic attributes, among others. Because of the very low toxicity, these terpenes are already widely used as food additives and in cosmetic products. Thus, they have been proven safe and well-tolerated.

Pharmacological evaluation of smooth muscle relaxant and cardiac-modulation potential of Phyla nodiflora in ex-vivo and in-vivo experiments

OBJECTIVE

To investigate the pharmacological basis of its uses of Phyla nodiflora (P. nodiflora) for the treatment of anomalies predominantly by smooth muscle containing tissues such as gastrointestinal/vascular/broncho spasm and cardiovascular modulation.

METHODS

The crude hydroalcoholic extract of P. nodiflora (Pn.Cr) and its fractions were evaluated on isolated rabbit jejunum, rat trachea, aorta and atrium. To access the contractile or relaxant effects of testing materials, the tissues were mounted in isolated organ bath and responses were recorded with transducers coupled with data acquisition system. BALB/c mice were challenged with castor oil for the assessment of in-vivo antidiarrheal activity. Normotensive rats were used for in-vivo hypotensive study.

RESULTS

Hydroalcoholic extract of Pn.Cr at variable concentrations inhibited the natural spontaneous rhythm and 80 mmol/L K⁺ mediated contractions in isolated segment of jejunum with EC₅₀ values of 3.18 and 1.91 mg/mL respectively. Verapamil, a Ca²⁺ channel blocker, demonstrated akin pattern in jejunum and therefore possibly suggesting calcium blocking activity. On isolated rat tracheal tissue, Pn.Cr showed relaxation of high-K⁺ and carbachol mediated contractions (EC₅₀ values: 1.24 and 2.42 mg/mL). Pn.Cr treatment relaxed the rat aortic ring in a cumulative doses with high-K⁺ and phenylephrine-induced contractions (EC₅₀ values 0.25 and 0.92 mg/mL). Activity based fractionation of Pn.Cr showed that dichloromethane fraction was more potent for relaxing the tissues spasm compared to aqueous fraction. In-vivo experiments, significant protection by Pn.Cr (P < 0.05) was observed in castor oil-induced diarrhea (50-500 mg/kg) whereas hypotensive effect in anesthetized rats was seen at the dose range of 1-10 mg/kg of Pn.Cr (P < 0.05).

CONCLUSION

This study suggests the blockage of calcium channel in the smooth muscles as a pharmacological application to make usage of P. nodiflora in the management of diarrhea, asthma and hypotensive effect.

In vitro study of anti-coccidial activity of essential oils from indigenous plants against Eimeria tenella

This study was designed to evaluate the in vitro anticoccidial properties against Eimeria tenella of different essential oils and their major active components. Efficacy of ten essential oils from different Thai indigenous plants were preliminarily screened and only those with potential were further tested for effective concentrations and identifying their active compounds. Oocysticidal property was evaluated in term of sporulation inhibition of oocysts and the percentage of unsporulated, sporulated and degenerated oocysts, after treatment with 125μg/ml of the selected essential oil, the sample was enumerated by haemocytometer, while coccidiocidal activity was assessed by the inhibition of sporozoite invasion in MDBK cell lines. Results showed that only Boesenbergia pandurata and Ocimum basilicum essential oils had strong sporulation inhibition activity by providing a higher ratio of degenerated oocysts and their IC₅₀ were 0.134 and 0.101mg/ml, respectively. GC-MS analysis of B. pandurata essential oil found trans-b-ocimene, camphor, 1,8-cineole, geraniol, camphene, methyl cinnamate, l-limonene and linalool as the major components, while methyl chavicol, α-bergamotene, 1,8-cineole and trans-β-ocimene were the main compounds of O. basilicum essential oil. Methyl cinnamate and camphor were the active components of B. pandurata oil, whereas methyl chavicol was the active component of O. basilicum oil by exhibiting the oocysticidal effect against E. tenella with IC₅₀ values of 0.008, 0.023 and 0.054mg/ml, respectively. Furthermore, B. pandurata and O. basilicum oils also showed a strong cytotoxic property against coccidia with more than 70% inhibition of sporozoite invasion in MDBK cell lines, and their IC₅₀ were 0.004 and 0.004mg/ml, respectively. Methyl cinnamate as well as camphor from B. pandurata and methyl chavicol from O. basilicum were also effective with IC₅₀ values of 0.029, 0.023, and 0.022mg/ml, respectively.

Association of rat thoracic aorta dilatation by astragaloside IV with the generation of endothelium-derived hyperpolarizing factors and nitric oxide, and the blockade of Ca2+ channels

The aim of the present study was to elucidate the roles of endothelium-derived hyperpolarizing factors (EDHFs) and nitric oxide (NO) in mediating the vasodilatation response to astragaloside IV and the effects of astragaloside IV on voltage-dependent Ca²⁺ channels and receptor-operated Ca²⁺ channels in rat thoracic aortic rings precontracted with potassium chloride (KCl; 60 mM) or phenylephrine (PHE; 1 µM). The results showed that astragaloside IV (1×10⁻⁴-3×10⁻¹ g/l) concentration-dependently relaxed the contraction induced by KCl (10–90 mM) or PHE (1×10⁻⁹-3×10⁻⁵ µM) and inhibited concentration-contraction curves for the two vasoconstrictors in the aortic rings. Preincubation with N^ω-nitro-L-arginine methyl ester (L-NAME, 100 µM) significantly attenuated astragaloside IV-induced relaxation in the endothelium-intact and -denuded arterial rings precontracted with PHE. Astragaloside IV, following preincubation with L-NAME (100 µM) plus indomethacin (10 µM), exerted vasodilatation, which was depressed by tetraethtylamine (1 mM) and propargylglycine (100 µM), but not by carbenoxolone (10 µM), catalase (500 U/ml) or proadifen hydrochloride (10 µM). The action mode of astragaloside IV was evident in comparison to nifedipine. Inhibition of PHE-induced contraction by astragaloside IV (100 mg/l) was more potent compared to inhibition of KCl-induced contraction, while inhibition of KCl-induced contraction by nifedipine (100 mg/l) was more potent compared to inhibition of PHE-induced contraction by nifedipine (100 mg/l). In addition, the combination of astragaloside IV and nifedipine exhibited synergistic and additive inhibitory effects on contraction evoked by KCl, which was similar to PHE. In conclusion, astragaloside IV, as a Ca²⁺ antagonist, relaxes the vessels through the blockade of superior receptor-operated Ca²⁺ and inferior voltage-dependent Ca²⁺ channels, which modulate NO from vascular endothelial cells and vascular smooth muscle cells, and EDHFs including K⁺ and hydrogen sulfide.

Inhibition of human α7 nicotinic acetylcholine receptors by cyclic monoterpene carveol

Cyclic monoterpenes are a group of phytochemicals with antinociceptive, local anesthetic, and anti-inflammatory actions. Effects of cyclic monoterpenes including vanilin, pulegone, eugenole, carvone, carvacrol, carveol, thymol, thymoquinone, menthone, and limonene were investigated on the functional properties of the cloned α7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes. Monoterpenes inhibited the α7 nicotinic acetylcholine receptor in the order carveol>thymoquinone>carvacrol>menthone>thymol>limonene>eugenole>pulegone≥carvone≥vanilin. Among the monoterpenes, carveol showed the highest potency on acetylcholine-induced responses, with IC50 of 8.3µM. Carveol-induced inhibition was independent of the membrane potential and could not be reversed by increasing the concentration of acetylcholine. In line with functional experiments, docking studies indicated that cyclic monoterpenes such as carveol may interact with an allosteric site located in the α7 transmembrane domain. Our results indicate that cyclic monoterpenes inhibit the function of human α7 nicotinic acetylcholine receptors, with varying potencies.

The Role of Eugenol in the Prevention of Acute Pancreatitis-Induced Acute Kidney Injury: Experimental Study

Aim. Acute pancreatitis is an inflammatory intra-abdominal disease, which takes a severe form in 15–20% of patients and can result in high mortality especially when complicated by acute renal failure. The aim of this study is to assess the possible reduction in the extent of acute kidney injury after administration of eugenol in an experimental model of acute pancreatitis. Materials and Methods. 106 male Wistar rats weighing 220–350 g were divided into 3 groups: (1) Sham, with sham surgery; (2) Control, with induction of acute pancreatitis, through ligation of the biliopancreatic duct; and (3) Eugenol, with induction of acute pancreatitis and eugenol administration at a dose of 15 mg/kg. Serum urea and creatinine, histopathological changes, TNF-α, IL-6, and MPO activity in the kidneys were evaluated at predetermined time intervals. Results. The group that was administered eugenol showed milder histopathological changes than the Control group, TNF-α activity was milder in the Eugenol group, and there was no difference in activity for MPO and IL-6. Serum urea and creatinine levels were lower in the Eugenol group than in the Control group. Conclusions. Eugenol administration was protective for the kidneys in an experimental model of acute pancreatitis in rats.

Annickia affinis and A. chlorantha (Enantia chlorantha)--A review of two closely related medicinal plants from tropical Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Annickia affinis (Exell) Versteegh & Sosef, closely related to A. chlorantha Setten & P.J.Maas (both species also referred to as Enantia chlorantha Oliv.), from the Annonaceae family, are multi-purpose medicinal plants used widely across tropical Africa. The two Annickia species are morphologically distinct from each other and have different distribution patterns, but are frequently confused. Furthermore, the name Enantia chlorantha is an illegitimate name, but is still used today.

MATERIALS AND METHODS

A review of the literature was undertaken and an in-depth analysis of previous research and future prospectives are considered. While a myriad of publications cite the species "Enantia chlorantha", this is not the case for A. affinis and A. chlorantha, and no reviews are available for any of the species to date. Consequently, a summary of their ethnobotany, phytochemistry and biological properties is presented here (for the period 1933 - November 2014) in order to substantiate their traditional importance as medicines for rural people in Africa.

RESULTS

To this effect, these species seem to be the preferred traditional treatments for malaria in tropical Africa, an area suffering heavily under the malaria pandemic. Their chemical composition is dominated particularly by various isoquinoline alkaloids, as well as by acetogenins and sesquiterpenes, which have been isolated from the bark and leaves. All three of these classes of compounds have been reported to exhibit noteworthy biological activity.

CONCLUSIONS

Due to their widespread use, especially of the bark, these species have already been categorized as threatened with extinction. Consequently this study further aims to identify areas where more research needs to be conducted involving these important species, and also to suggest possible means of increasing the biological activities of their extracts as a way to conserve the species.

Inhibition of Nav1.7 channels by methyl eugenol as a mechanism underlying its antinociceptive and anesthetic actions

AIM

Methyl eugenol is a major active component extracted from the Chinese herb Asari Radix et Rhizoma, which has been used to treat toothache and other pain. Previous in vivo studies have shown that methyl eugenol has anesthetic and antinociceptive effects. The aim of this study was to determine the possible mechanism underlying its effect on nervous system disorders.

METHODS

The direct interaction of methyl eugenol with Na(+) channels was explored and characterized using electrophysiological recordings from Nav1.7-transfected CHO cells.

RESULTS

In whole-cell patch clamp mode, methyl eugenol tonically inhibited peripheral nerve Nav1.7 currents in a concentration- and voltage-dependent manner, with an IC50 of 295 μmol/L at a -100 mV holding potential. Functionally, methyl eugenol preferentially bound to Nav1.7 channels in the inactivated and/or open state, with weaker binding to channels in the resting state. Thus, in the presence of methyl eugenol, Nav1.7 channels exhibited reduced availability for activation in a steady-state inactivation protocol, strong use-dependent inhibition, enhanced binding kinetics, and slow recovery from inactivation compared to untreated channels. An estimation of the affinity of methyl eugenol for the resting and inactivated states of the channel also demonstrated that methyl eugenol preferentially binds to inactivated channels, with a 6.4 times greater affinity compared to channels in the resting state. The failure of inactivated channels to completely recover to control levels at higher concentrations of methyl eugenol implies that the drug may drive more drug-bound, fast-inactivated channels into drug-bound, slow-inactivated channels.

CONCLUSION

Methyl eugenol is a potential candidate as an effective local anesthetic and analgesic. The antinociceptive and anesthetic effects of methyl eugenol result from the inhibitory action of methyl eugenol on peripheral Na(+) channels.

Effects of monoterpenes on ion channels of excitable cells

Monoterpenes are a structurally diverse group of phytochemicals and a major constituent of plant-derived 'essential oils'. Monoterpenes such as menthol, carvacrol, and eugenol have been utilized for therapeutical purposes and food additives for centuries and have been reported to have anti-inflammatory, antioxidant and analgesic actions. In recent years there has been increasing interest in understanding the pharmacological actions of these molecules. There is evidence indicating that monoterpenes can modulate the functional properties of several types of voltage and ligand-gated ion channels, suggesting that some of their pharmacological actions may be mediated by modulations of ion channel function. In this report, we review the literature concerning the interaction of monoterpenes with various ion channels.

The vasodilating effect of a Hintonia latiflora extract with antidiabetic action

In the present study, it is shown for the first time that an extract of Hintonia latiflora (HLE) which is used as an antidiabetic herbal medicine, is not only able to decrease blood glucose concentration but additionally exerts a vasodilating effect. Accordingly, this extract might have a positive influence on diabetes-associated dysfunction of blood vessels. The vasodilating effect was demonstrated in vitro in aortic rings of guinea pigs as well as in vivo in rabbits. Aortic rings pre-contracted with noradrenaline (NA) could completely be relaxed by HLE (EC50: 51.98 mg/l). In contrast, potassium-induced contractions were not diminished by HLE. Therefore, it can be suggested that the vasodilating effect of HLE is primarily the result of an inhibition of G protein-induced increase in intracellular calcium and not of a blockade of voltage-operated L-type calcium channels. The neoflavonoid coutareagenin (COU), a constituent of HLE which in part is responsible for the blood glucose-lowering effect of HLE, also relaxed NA-induced contractions of aortic rings (EC50: 32.55 mg/l) and only weakly inhibited potassium-induced contractions. Experiments in aortic rat cells revealed that calcium transients evoked by vasopressin were suppressed by 60 mg/l COU supporting the idea of an inhibition of G protein-induced intracellular calcium release by a constituent of HLE. To study the effect of HLE on vascular tone under in vivo conditions, ultrasound measurements were carried out in conscious rabbits which received a single oral dose of HLE. Under the influence of HLE, a vasodilation combined with a lowering of blood flow velocity could be observed in the abdominal aorta and the common carotid artery. Additionally, a decrease in blood glucose concentration in the HLE group occurred. The combination of a blood glucose-lowering with a vasodilating effect may be helpful for reducing angiopathies, typical long-term complications in patients with diabetes mellitus.

Geraniol blocks calcium and potassium channels in the mammalian myocardium: useful effects to treat arrhythmias

Geraniol is a monoterpene present in several essential oils, and it is known to have a plethora of pharmacological activities. In this study, we explored the contractile and electrophysiological properties of geraniol and its antiarrhythmic effects in the heart. The geraniol effects on atrial contractility, L-type Ca(2+) current, K(+) currents, action potential (AP) parameters, ECG profile and on the arrhythmia induced by ouabain were evaluated. In the atrium, geraniol reduced the contractile force (~98%, EC = 1,510 ± 160 μM) and diminished the positive inotropism of CaCl2 and BAY K8644. In cardiomyocytes, the IC a,L was reduced by 50.7% (n = 5) after perfusion with 300 μM geraniol. Moreover, geraniol prolonged the AP duration (APD) measured at 50% (n = 5) after repolarization, without changing the resting potential. The increased APD could be attributed to the blockade of the transient outward K(+) current (Ito ) (59.7%, n = 4), the non-inactivation K(+) current (Iss ) (39.2%, n = 4) and the inward rectifier K(+) current (IK 1 ) (33.7%, n = 4). In isolated hearts, geraniol increased PRi and QTi without affecting the QRS complex (n = 6), and it reduced both the left ventricular pressure (83%) and heart rate (16.5%). Geraniol delayed the time to onset of ouabain-induced arrhythmias by 128%, preventing 30% of the increase in resting tension (n = 6). Geraniol exerts its negative inotropic and chronotropic responses in the heart by decreasing both L-type Ca(2+) and voltage-gated K(+) currents, ultimately acting against ouabain-induced arrhythmias.

Effects of eugenol on resting tension of rat atria

In cardiac and skeletal muscle, eugenol (μM range) blocks excitation-contraction coupling. In skeletal muscle, however, larger doses of eugenol (mM range) induce calcium release from the sarcoplasmic reticulum. The effects of eugenol are therefore dependent on its concentration. In this study, we evaluated the effects of eugenol on the contractility of isolated, quiescent atrial trabeculae from male Wistar rats (250-300 g; n=131) and measured atrial ATP content. Eugenol (1, 3, 5, 7, and 10 mM) increased resting tension in a dose-dependent manner. Ryanodine [100 µM; a specific ryanodine receptor (RyR) blocker] and procaine (30 mM; a nonspecific RyR blocker) did not block the increased resting tension induced by eugenol regardless of whether extracellular calcium was present. The myosin-specific inhibitor 2,3-butanedione monoxime (BDM), however, reversed the increase in resting tension induced by eugenol. In Triton-skinned atrial trabeculae, in which all membranes were solubilized, eugenol did not change resting tension, maximum force produced, or the force vs pCa relationship (pCa=-log [Ca²⁺]). Given that eugenol reduced ATP concentration, the increase in resting tension observed in this study may have resulted from cooperative activation of cardiac thin filaments by strongly attached cross-bridges (rigor state).

Drug-induced functional cardiotoxicity screening in stem cell-derived human and mouse cardiomyocytes: effects of reference compounds

INTRODUCTION

Early prediction of drug-induced functional cardiotoxicity requires robust in-vitro systems suitable for medium/high throughput and easily accessible cardiomyocytes with defined reproducible properties. The xCELLigence Cardio system uses 96-well plates with interdigitated electrodes that detect the impedance changes of rhythmic contractions of stem cell-derived cardiomyocyte (SC-CM) layers. Here, we report on our initial screening experience in comparison to established (multi)cellular and in-vivo models.

METHODS

Impedance signals from human iPSC-CM (iCells™) and mouse eSC-CM (Cor.At™) were analyzed for contraction amplitude (CA) and duration, rise/fall time, beating rate (BR) and irregularity.

RESULTS

Following solution exchange, impedance signals re-approximated steady-state conditions after about 2 (Cor.At™) and 3h (iCells™); these time points were used to analyze drug effects. The solvent DMSO (≤1%) hardly influenced contraction parameters in Cor.At™, whereas in iCells™ DMSO (>0.1%) reduced CA and enhanced BR. The selective hERG K⁺ channel blockers E-4031 and dofetilide reduced CA and accelerated BR (≥30 nM) according to the analysis software. The latter, however, was due to burst-like contractions (300 nM) that could be detected only by visual inspection of recordings, and were more pronounced in Cor.At™ as in iCells™. In cardiac myocytes and tissue preparations, however, E4031 and dofetilide have been reported to increase cell shortening and contractile force and to reduce BR. Compounds (pentamidine, HMR1556, ATX2, TTX, and verapamil) with other mechanisms of action were also investigated; their effects differed partially between cell lines (e.g. TTX) and compared to established (multi)cellular models (e.g. HMR1556, ouabain).

CONCLUSION

Mouse and human stem cell-derived cardiomyocytes respond differently to drugs and these responses occasionally also differ from those originating from established in-vitro and in-vivo models. Hence, drug-induced cardiotoxic effects may be detected with this system, however, the predictive or even translational value of results is considered limited and not yet firmly established.

Chemical Constituents of Blumea balsamifera of Indonesia and Their Protein Tyrosine Phosphatase 1B Inhibitory Activity

A methanol extract of the leaves of Blumea balsamifera (L.) DC. (Asteraceae) afforded a new guaian-type sesquiterpene, epiblumeaene K (1), together with four known guaian-type sesquiterpenes (2–5), three known sesquiterpenes (6–8), and nine known flavonoids (9–17) by a combination of chromatography and preparative TLC techniques. Their structures were elucidated by extensive spectroscopic methods and comparison with the literature data. Among the isolated compounds, a known sesquiterpene, β-caryophyllene 8 R,9 R-oxide (6), exhibited a significant PTP1B inhibitory activity in a dose-dependent manner, with an IC50 value of 25.8μM (5.62μg/mL).

Characterizing the effects of Eugenol on neuronal ionic currents and hyperexcitability

RATIONALE

Eugenol (EUG, 4-allyl-2-methoxyphenol), the main component of essential oil extracted from cloves, has various uses in medicine because of its potential to modulate neuronal excitability. However, its effects on the ionic mechanisms remains incompletely understood.

OBJECTIVES

We aimed to investigate EUG's effects on neuronal ionic currents and excitability, especially on voltage-gated ion currents, and to verify the effects on a hyperexcitability-temporal lobe seizure model.

METHODS

With the aid of patch-clamp technology, we first investigated the effects of EUG on ionic currents in NG108-15 neuronal cells differentiated with cyclic AMP. We then used modified Pinsky-Rinzel simulation modeling to evaluate its effects on spontaneous action potentials (APs). Finally, we investigated its effects on pilocarpine-induced seizures in rats.

RESULTS

EUG depressed the transient and late components of I(Na) in the neurons. It not only increased the degree of I(Na) inactivation, but specifically suppressed the non-inactivating I(Na) (I(Na(NI))). Its inhibition of I (Na(NI)) was reversed by tefluthrin. In addition, EUG diminished L-type Ca(2+) current and delayed rectifier K(+) current only at higher concentrations. EUG's effects on APs frequency reduction was verified by the simulation modeling. In pilocarpine-induced seizures, the EUG-treated rats showed no shorter seizure latency but a lower seizure severity and mortality than the control rats. The EUG's effect on seizure severity was occluded by the I(Na(NI)) antagonist riluzole.

CONCLUSION

The synergistic blocking effects of I (Na) and I(Na(NI)) contributes to the main mechanism through which EUG affects the firing of neuronal APs and modulate neuronal hyperexcitability such as pilocarpine-induced temporal lobe seizures.

Chemical compositions and properties of Schinus areira L. essential oil on airway inflammation and cardiovascular system of mice and rabbits

The main purpose was to investigate the effects of essential plant-oil of Schinus areira L. on hemodynamic functions in rabbits, as well as myocardial contractile strength and airways inflammation associated to bacterial endotoxin lipopolysaccharide (LPS) in mice. This study shows the important properties of the essential oil (EO) of S. areira studied and these actions on lung with significant inhibition associated to LPS, all of which was assessed in mice bronchoalveolar lavage fluid and evidenced by stability of the percentage of alveolar macrophages, infiltration of polymorphonuclear leukocytes and tumor necrosis factor-α concentration, and without pathway modifications in conjugated dienes activity. Clinical status (morbidity or mortality), macroscopic morphology and lung/body weight index were unaffected by the administration of the EO S. areira. Furthermore, the ex vivo analysis of isolated hearts demonstrated the negative inotropic action of the EO of S. areira in a mice model, and in rabbits changes in the hemodynamic parameters, such as a reduction of systolic blood pressure. We conclude that EO S. areira could be responsible for modifications on the cardiovascular and/or airway parameters.

Presynaptic enhancement by eugenol of spontaneous excitatory transmission in rat spinal substantia gelatinosa neurons is mediated by transient receptor potential A1 channels

Eugenol, which is contained in several plants including clove, has been widely used as an analgesic and anti-inflammatory drug in the dental clinic. Eugenol also has anesthetic effects and produces sedation and the reduction of convulsion threshold. These benefits have been partly attributed to the effects of eugenol on neural tissues, such as inhibition of voltage-gated ion channels. As expected from the fact that eugenol is a vanilloid compound, this drug activates transient receptor potential (TRP) V1 channels in the peripheral nervous system (PNS). Although eugenol affects synaptic transmission in the central nervous system (CNS), this has not yet been fully examined. We investigated how eugenol affects spontaneous glutamatergic excitatory transmission in substantia gelatinosa (SG; lamina II of Rexed) neurons of adult rat spinal cord slices by use of the blind whole-cell patch-clamp technique. Bath-applied eugenol reversibly enhanced spontaneous excitatory transmission and produced an outward current at -70 mV in SG neurons. The former action was due to a large increase in the frequency of spontaneous excitatory postsynaptic current (sEPSC) with a small increase in the amplitude. These actions of eugenol were seen by its repeated application and resistant to a voltage-gated Na(+) channel blocker tetrodotoxin. The effect of eugenol on sEPSC frequency was concentration-dependent with an EC(50) value of 3.8 mM and unaffected by a TRPV1 antagonist capsazepine, whereas inhibited by a nonspecific TRP antagonist ruthenium red and a TRPA1 antagonist HC-030031. On the other hand, the eugenol-induced outward current was not affected by these TRP antagonists. It is concluded that eugenol activates TRPA1 channels in the SG, leading to an increase in the spontaneous release of L-glutamate to SG neurons, and that eugenol also produces a membrane hyperpolarization that is not mediated by TRP channels. Eugenol is suggested to activate different types of TRP channel between the PNS and CNS.

Using maximum heart rate as a rapid screening tool to determine optimum temperature for aerobic scope in Pacific salmon Oncorhynchus spp

The mean ±s.e. optimum temperature (T(opt)) for aerobic scope in juvenile coho salmon Oncorhynchus kisutch was determined to be 17·0 ± 0·7° C. The repeated measures protocol took 3 weeks to complete the T(opt) determination using 12 fish tested at five temperatures separated by 2° C increments. This experiment also demonstrated that the T(opt) was associated with maximum heart rate (f(H)) failing to maintain a Q(10) -related increase with temperature. When maximum f(H) was produced in anaesthetized fish with pharmacological stimulation and f(H) measured from electrocardiogram recordings during acute warming, the Arrhenius break temperature (ABT) for Q(10) discontinuities in maximum f(H) (mean ±s.e. = 17·1 ± 0·5° C for 15 ppm clove oil and 16·5 ± 0·2° C for 50 ppm MS-222) was statistically indistinguishable from the T(opt) measured using aerobic scope. Such a determination took only 3 days rather than 3 weeks. Therefore, it is proposed that determining ABT for discontinuities in maximum f(H) in anaesthetized fish presents itself as a valuable, high-throughput screening tool to assess T(opt) in fishes, a metric that has become recognized as being extremely valuable in fish biology and fisheries management.

Eugenol: A Natural Compound with Versatile Pharmacological Actions

Eugenol, the major constituent of clove oil, has been widely used for its anesthetic and analgesic action in dentistry. Eugenol exhibits pharmacological effects on almost all systems and our aim is to review the research work that has identified these pharmacological actions. Eugenol possesses significant antioxidant, anti-inflammatory and cardiovascular properties, in addition to analgesic and local anesthetic activity. The metabolism and pharmacokinetics of the compound in humans have been studied. Eugenol has also been used as a penetration enhancer. The compound is a very promising candidate for versatile applications, and the design of new drugs based on the pharmacological effects of eugenol could be beneficial.

Functional characterization of cardiomyocytes derived from murine induced pluripotent stem cells in vitro

Several types of terminally differentiated somatic cells can be reprogrammed into a pluripotent state by ectopic expression of Klf4, Oct3/4, Sox2, and c-Myc. Such induced pluripotent stem (iPS) cells have great potential to serve as an autologous source of cells for tissue repair. In the process of developing iPS-cell-based therapies, the major goal is to determine whether differentiated cells derived from iPS cells, such as cardiomyocytes (CMs), have the same functional properties as their physiological in vivo counterparts. Therefore, we differentiated murine iPS cells to CMs in vitro and characterized them by RT-PCR, immunocytochemistry, and electrophysiology. As key markers of cardiac lineages, transcripts for Nkx2.5, alphaMHC, Mlc2v, and cTnT could be identified. Immunocytochemical stainings revealed the presence of organized sarcomeric actinin but the absence of mature atrial natriuretic factor. We examined characteristics and developmental changes of action potentials, as well as functional hormonal regulation and sensitivity to channel blockers. In addition, we determined expression patterns and functionality of cardiac-specific voltage-gated Na+, Ca2+, and K+ channels at early and late differentiation stages and compared them with CMs derived from murine embryonic stem cells (ESCs) as well as with fetal CMs. We conclude that iPS cells give rise to functional CMs in vitro, with established hormonal regulation pathways and functionally expressed cardiac ion channels; CMs generated from iPS cells have a ventricular phenotype; and cardiac development of iPS cells is delayed compared with maturation of native fetal CMs and of ESC-derived CMs. This difference may reflect the incomplete reprogramming of iPS cells and should be critically considered in further studies to clarify the suitability of the iPS model for regenerative medicine of heart disorders.

Effects of anethole and structural analogues on the contractility of rat isolated aorta: Involvement of voltage-dependent Ca2+-channels

Anethole is a naturally occurring aromatic oxidant, present in a variety of medicinal plant extracts, which is commonly used by the food and beverage industry. Despite its widespread occurrence and commercial use, there is currently little information regarding effects of this compound on the vasculature. Therefore the actions of anethole on the contractility of rat isolated aorta were compared with those of eugenol, and their respective isomeric forms, estragole and isoeugenol. In aortic rings precontracted with phenylephrine (PE; 1 microM), anethole (10(-6) M-10(-4) M) induced contraction in preparations possessing an intact endothelium, but not in endothelium-denuded tissues. At higher concentrations (10(-3) M-10(-2) M), anethole-induced concentration-dependent and complete relaxation of all precontracted preparations, irrespective of whether the endothelium was intact or not, an action shared by eugenol, estragole and isoeugenol. The contractile and relaxant effects of anethole in PE-precontracted preparations were not altered by L-NAME (10 microM) or indomethacin (10 microM), indicating that neither nitric oxide nor prostaglandins were involved in these actions. The mixed profile of effects was not confined to PE-mediated contraction, since similar responses were obtained to anethole when tissues were precontracted with 25 mM KCl. Anethole and estragole (10(-6)-10(-4) M), but not eugenol or isoeugenol, increased the basal tonus of endothelium-denuded aortic rings, an action that was abolished by VDCC blockers nifedipine (1 microM) and diltiazem (1 microM), or by withdrawal of extracellular Ca(2+). Our data suggest complex effects of anethole on isolated blood vessels, inducing contraction at lower doses, mediated via opening of voltage-dependent Ca(2+)-channels, and relaxant effects at higher concentrations that are shared by structural analogues.

Differential effects of anesthetics on electrical properties of the rainbow trout (Oncorhynchus mykiss) heart

We compared electrocardiographic signals in hatchery-reared, non-spinally-transected, immature rainbow trout (Oncorhynchus mykiss Walbaum) under clove oil (25 ppm), tricaine methanesulfonate (tricaine, 60 ppm), and benzocaine (108 ppm) general anesthesia (35 min, 14 degrees C). For all 3 anesthetics, the mean heart rate (HR) and QRS amplitude did not differ, and QRS duration and QT interval were independent of HR. Heart rate variability (HRV) was significantly (4-fold, P=0.032) higher under benzocaine than under clove oil and tricaine, but did not differ between clove oil and tricaine. QRS duration differed between groups (P<0.001, F=121); benzocaine anesthesia resulted in longer QRS complexes compared to clove oil (P<0.001) and tricaine (P<0.001) anesthesia, and QRS complexes under clove oil were longer than those under tricaine (P<0.001). High HRV and QRS amplitude variation with benzocaine were associated with HR oscillations as anesthetic exposure time increased, and suggest benzocaine toxicity which may influence cardiac function studies. Similar clove oil and tricaine ECG patterns suggest comparable autonomic effects, and maintenance of myocardial excitability. Given its low cost, ease of use, and similar ECG profiles to tricaine, clove oil is a viable alternative for studies of cardiac function in anesthetized rainbow trout.

Cytotoxicity of Marchantia convoluta leaf extracts to human liver and lung cancer cells

The cytotoxicity of three extracts (petroleum ether, ethyl acetate and n-butanol) from a plant used in folk medicine, Marchantia convoluta, to human non-small cell lung carcinoma (H1299) and liver carcinoma (HepG2) cell lines was tested. After 72-h incubation of lung and liver cancer cell cultures with varying concentrations of extracts (15 to 200 microg/mL), cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and reported in terms of cell viability. The extracts that showed a significant cytotoxicity were subjected to gas chromatography-mass spectrometry analysis to identify the components. The ethyl acetate, but not the petroleum ether or n-butanol extract, had a significant cytotoxicity against lung and liver carcinoma cells with IC50 values of 100 and 30 microg/mL, respectively. A high concentration of ethyl acetate extract (100 microg/mL) rapidly reduced the number of H1299 cells. At lower concentrations of ethyl acetate extract (15, 30, and 40 microg/mL), the numbers of HepG2 cells started to decrease markedly. Gas chromatography-mass spectrometry analysis of the ethyl acetate extract revealed the presence of several compounds such as phytol (23.42%), 1,2,4-tripropylbenzene (13.09%), 9-cedranone (12.75%), ledene oxide (7.22%), caryophyllene (1.82%), and caryophyllene oxide (1.15%). HPLC analysis result showed that there were no flavonoids in ethyl acetate extract, but flavonoids are abundant in n-butanol extract. Further studies are needed regarding the identification, toxicity, and mechanism of action of active compounds.

Nifedipine represses ion channels, transporters and Ca2+-binding proteins in hearts of spontaneously hypertensive rats

The Ca(2+) antagonists nifedipine has been used for more than three decades to treat hypertension, but its effects on the transcriptional regulation of cardiac genes are basically unknown. We therefore studied expression of genes coding for ion channels, ion transporters and associated partners as well as Ca(2+)-binding proteins in ventricular tissue of normotensive and spontaneously hypertensive (SH) rats after repeated intraperitoneally (i.p.) dosing of nifedipine. Notably, we observed significant (P < 0.05) repression in transcript levels of most of the genes investigated, including cardiac Na(+), K(+), Ca(2+)-channels (L-type Ca(2+)-channel, K(ir)3.4, K(ir)6.1, Na(v)1.5), ATP-driven ion exchangers (Na(+)-K(+)-ATPase, NCX-1, PMCA 2 and 4, SERCA 2a and 2b) and their associated partners (phospholamban, RyR-2) as well as cytoskeletal proteins (alpha and beta-MHC, alpha cardiac and alpha skeletal actin, troponin T and I). Repression in transcript levels was, however, only seen in ventricular tissue of hypertensive animals. This points to fundamental differences in the mode of action of nifedipine in diseased and healthy animals. Indeed, this preponderance of repressed genes will promote disturbed ion homeostasis to result in contractile dysfunction. It is of considerable importance that repressed gene expression was also seen in end-stage human heart failure. We propose repression of cardiac-specific gene expression as a hallmark of nifedipine treatment in hypertrophic hearts.

Temporal variation of chemical composition and relaxant action of the essential oil of Ocimum gratissimum L. (Labiatae) on guinea-pig ileum

The medicinal plant Ocimum gratissimum L. (Labiatae) is widely encountered in the Northeast of Brasil where it is used to treat digestive problems. Its leaves have an essential oil (EOOG) content whose chemical composition varies according to the time of plant collection. We have compared the effects of the EOOG, collected at 08:00 a.m. (EOOG8) and at 12:00 a.m. (EOOG12), on the relaxation of guinea-pig isolated ileum. Both EOOG8 and EOOG12 (30-300 microg/ml) reversibly relaxed the spontaneous tonus of the guinea-pig ileum in a concentration-dependent manner, with similar IC50 values (49.3 and 23.8 microg/ml, respectively). The magnitude of the decrease in resting tonus was similar to that of the recognised smooth muscle relaxant papaverine. EOOG8 and EOOG12 relaxed 60 mM KCl-precontracted preparations similarly (38.33 +/- 9.91 microg/ml and 35.53 +/- 6.70), whereas a significantly more potent relaxant effect of EOOG12 compared to EOOG8 was observed when tissues were contracted using 10 microM acetylcholine (IC50 values of 69.55 +/- 4.93 and 128.16 +/- 15.70 microg/ml, respectively; p < 0.05). The principal constituents of the essential oil, eugenol and cineole, also relaxed KCl-precontracted preparations, although they were less potent than EOOG, suggesting that they alone were not responsible for EOOG-induced relaxations. Our results show that the essential oil extracted from the leaves of O. gratissimum L., collected at different time periods, exerts significant relaxant effects on isolated guinea-pig ileum which may underlie the therapeutic action of the plant.

Effects of eugenol, an essential oil, on the mechanical and electrical activities of cardiac muscle

Eugenol (EUG) acts as a calcium antagonist but effects on the contractile proteins could also occur. We investigated inotropic effects of EUG in rat left ventricular papillary muscles, measuring isometric force, time variables, and post rest potentiation and EUG actions on the effects of Ca2+ (0.62 to 2.5 mM) and isoproterenol (5 ng/ml), on myosin ATPase activity and on the calcium currents in single ventricular myocytes. EUG reduced tension and time variables without altering the sarcoplasmic reticulum activity increasing post-pause relative potentiation. Isoproterenol and Ca2+ counteract these negative inotropic effects. Tetanic tension diminished, but not the myosin ATPase activity suggesting an isolated sarcolemmal effect. EUG 0.1 mM decreased the Ca2+ current amplitude in the entire potential range tested and 0.5 mM almost completely blocked this inward current. Results suggested that EUG depresses force without affecting the contractile machinery and its action is the only dependent blockade of the calcium inward current.

Effects of terpenoid phenol derivatives on calcium current in canine and human ventricular cardiomyocytes

Concentration-dependent (10-1000 microM) effects of terpenoid phenol derivatives were studied on L-type Ca(2+) current in isolated canine and human ventricular cardiomyocytes using the whole-cell configuration of patch clamp technique. Carvacrol, thymol and eugenol suppressed peak Ca(2+) current at +5 mV, having EC(50) values and Hill coefficients of 98+/-11, 158+/-7 and 187+/-15 microM and 1.42+/-0.05, 2.96+/-0.43 and 1.6+/-0.1, respectively, in canine myocytes. Zingerone displayed a weak effect (estimated EC(50): 2+/-0.37 mM, Hill coefficient: 0.73+/-0.07), while vanillin and guaiacol failed to substantially modify Ca(2+) current up to the concentration of 1 mM. In addition to tonic block, thymol and carvacrol, but not eugenol, evoked marked rate-dependent block at 2 Hz. Carvacrol and eugenol accelerated inactivation of Ca(2+) current and caused leftward shift in the voltage dependence of steady-state inactivation without altering activation kinetics. Carvacrol, but not eugenol, increased the time constant of recovery from inactivation. These effects of carvacrol and eugenol developed rapidly and were largely reversible. In myocytes isolated from undiseased human hearts, the effect of carvacrol was similar to that observed in canine cells. It is concluded that suppression of cardiac Ca(2+) currents by phenol derivatives is influenced by the substituent in the benzene ring, and the blocking effect of these drugs may involve interactions with the inactivation machinery of the channel.