Rutaecarpine targets hERG channels and participates in regulating electrophysiological properties leading to ventricular arrhythmia.

Drug-mediated or medical condition-mediated disruption of hERG function accounts for the main cause of acquired long-QT syndrome (acLQTs), which predisposes affected individuals to ventricular arrhythmias (VA) and sudden death. Many Chinese herbal medicines, especially alkaloids, have risks of arrhythmia in clinical application. The characterized mechanisms behind this adverse effect are frequently associated with inhibition of cardiac hERG channels. The present study aimed to assess the potent effect of Rutaecarpine (Rut) on hERG channels. hERG-HEK293 cell was applied for evaluating the effect of Rut on hERG channels and the underlying mechanism. hERG current (IhERG ) was measured by patch-clamp technique. Protein levels were analysed by Western blot, and the phosphorylation of Sp1 was determined by immunoprecipitation. Optical mapping and programmed electrical stimulation were used to evaluate cardiac electrophysiological activities, such as APD, QT/QTc, occurrence of arrhythmia, phase singularities (PSs), and dominant frequency (DF). Our results demonstrated that Rut reduced the IhERG by binding to F656 and Y652 amino acid residues of hERG channel instantaneously, subsequently accelerating the channel inactivation, and being trapped in the channel. The level of hERG channels was reduced by incubating with Rut for 24 hours, and Sp1 in nucleus was inhibited simultaneously. Mechanismly, Rut reduced threonine (Thr)/ tyrosine (Tyr) phosphorylation of Sp1 through PI3K/Akt pathway to regulate hERG channels expression. Cell-based model unables to fully reveal the pathological process of arrhythmia. In vivo study, we found that Rut prolonged QT/QTc intervals and increased induction rate of ventricular fibrillation (VF) in guinea pig heart after being dosed Rut for 2 weeks. The critical reasons led to increased incidence of arrhythmias eventually were prolonged APD90 and APD50 and the increase of DF, numbers of PSs, incidence of early after-depolarizations (EADs). Collectively, the results of this study suggest that Rut could reduce the IhERG by binding to hERG channels through F656 and Y652 instantaneously. While, the PI3K/Akt/Sp1 axis may play an essential role in the regulation of hERG channels, from the perspective of the long-term effects of Rut (incubating for 24 hours). Importantly, the changes of electrophysiological properties by Rut were the main cause of VA.

Tremorgenic effects and functional metabolomics analysis of lolitrem B and its biosynthetic intermediates.

The neuroactive mycotoxin lolitrem B causes a neurological syndrome in grazing livestock resulting in hyperexcitability, muscle tremors, ataxia and, in severe cases, clonic seizures and death. To define the effects of the major toxin lolitrem B in the brain, a functional metabolomic study was undertaken in which motor coordination and tremor were quantified and metabolomic profiling undertaken to determine relative abundance of both toxin and key neurotransmitters in various brain regions in male mice. Marked differences were observed in the duration of tremor and coordination between lolitrem B pathway members, with some showing protracted effects and others none at all. Lolitrem B was identified in liver, kidney, cerebral cortex and thalamus but not in brainstem or cerebellum which were hypothesised previously to be the primary site of action. Metabolomic profiling showed significant variation in specific neurotransmitter and amino acid profiles over time. This study demonstrates accumulation of lolitrem B in the brain, with non-detectable levels of toxin in the brainstem and cerebellum, inducing alterations in metabolites such as tyrosine, suggesting a dynamic catecholaminergic response over time. Temporal characterisation of key pathways in the pathophysiological response of lolitrem B in the brain were also identified.

Molecular mechanisms involved in drug-induced liver injury caused by urate-lowering Chinese herbs: A network pharmacology study and biology experiments.

As an important part of the comprehensive treatment methods, the urate-lowering Chinese herbs could provide favorable clinical effects on hyperuricemia in its ability to invigorate spleen and remove dampness. Owing to the long-term duration, it brought up the potential adverse reactions (ADRs) and concerns about the drug-induced liver injury from these herbs. To address this problem, the bioinformatics approaches which combined the network pharmacology, computer simulation and molecular biology experiments were undertaken to elucidate the underlying drug-induced liver injury molecular mechanisms of urate-lowering Chinese herbs. Several electronic databases were searched to identify the potential liver injury compounds in published research. Then, the putative target profile of liver injury was predicted, and the interaction network was constructed based on the links between the compounds, corresponding targets and core pathways. Accordingly, the molecular docking simulation was performed to recognize the representative compounds with hepatotoxicity. Finally, the cell experiments were conducted to investigate the biochemical indicators and expression of the crucial protein that were closely associated with liver injury. In conclusion, the current research revealed that the compounds with potential liver injury including diosgenin, baicalin, saikosaponin D, tetrandrine, rutaecarpine and evodiamine from urate-lowering Chinese herbs, could lead to decline the survival rate of L-02 cell, increase the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) in cell-culture medium, enhance the expression of p-p38/p38, while the p38 inhibitor could achieve the trend of regulating and controlling liver injury. These research findings bring further support to the growing evidence that the mechanism of the liver injury induced by the compounds from urate-lowering Chinese herbs may be associated with the activation of p38α.

Development of a model for investigation of perennial ryegrass toxicosis in sheep.

AIMS To develop a clinical model of perennial ryegrass toxicosis (PRGT) based on feeding a known dose of lolitrem B and ergotamine, and to produce a consistent clinical presentation for assessment of disease pathophysiology, neurological changes and neurohistopathology. METHODS Male lambs, aged between 10-12 months, were randomly assigned to either Treatment (n=9) or Control (n=9) groups. Lambs in the Treatment group received feed containing a novel endophyte-infested perennial ryegrass seed, commencing on Day 0 of the Feeding phase with a low induction dose, then increasing after 3 days to provide 0.16 mg/kg live bodywight (LBW)/day of lolitrem B and 0.054 mg/kg LBW/day ergotamine. Lambs were examined daily and when defined signs of PRGT were observed they were transferred to the Testing phase. Neurological examinations, assessment of gait, surface electromyography (EMG) and mechanosensory nociceptive threshold testing were carried out and blood samples collected during both phases of the trial, with a full necropsy, histopathological examination and measurement of faecal cortisol metabolites (FCM) performed on Day 2 of the Testing phase. RESULTS Typical clinical signs of PRGT, including ataxia of vestibulocerebellar origin leading to stumbling, were observed in all Treatment lambs. The median interval from the start of the Feeding phase to entry into the Testing phase was 21 (min 18, max 34) days. Histopathological characterisation of neurological lesions included the presence of Purkinje cell vacuolation, pyknotic granular layer neurons and proximal axonal Purkinje cell spheroids. Lesions were most apparent within the vestibulocerebellum. Mean root-mean-square voltages from triceps EMG increased in Treatment lambs between Feeding phase Day 0 and Testing phase Day 2 (p<0.001). Daily water intake during the Testing phase for the Treatment group was less than in Control group lambs (p=0.002), and concentrations of FCM at necropsy were higher in Treatment compared to Control lambs (p=0.02). CONCLUSIONS AND CLINICAL RELEVANCE Lolitrem B and ergotamine dosing in feed on a live weight basis combined with neurological/gait assessment provides an effective model for investigation of PRGT and potential therapeutics. Assessment of gait changes using defined criteria and RMS voltages from EMG appear to be useful tools for the assessment of the severity of neurological changes.

The pyrrolidinoindoline alkaloid Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling.

AIM: Psm2, one of the pyrrolidinoindoline alkaloids isolated from whole Selaginella moellendorffii plants, has shown a potent antiplatelet activity. In this study, we further evaluated the antiplatelet effects of Psm2, and elucidated the underlying mechanisms. METHODS: Human platelet aggregation in vitro and rat platelet aggregation ex vivo were investigated. Agonist-induced platelet aggregation was measured using a light transmission aggregometer. The antithrombotic effects of Psm2 were evaluated in arteriovenous shunt thrombosis model in rats. To elucidate the mechanisms underlying the antiplatelet activity of Psm2, ELISAs, Western blotting and molecular docking were performed. The bleeding risk of Psm2 administration was assessed in a mouse tail cutting model, and the cytotoxicity of Psm2 was measured with MTT assay in EA.hy926 cells. RESULTS: Psm2 dose-dependently inhibited human platelet aggregation induced by ADP, U4619, thrombin and collagen with IC50 values of 0.64, 0.37, 0.35 and 0.87 mg/mL, respectively. Psm2 (1, 3, 10 mg/kg) administered to rats significantly inhibited platelet aggregation ex vivo induced by ADP. Psm2 (1, 3, 10 mg/mL, iv) administered to rats with the A-V shunt dose-dependently decreased the thrombus formation. Psm2 inhibited platelet adhesion to fibrinogen and collagen with IC50 values of 84.5 and 96.5 mg/mL, respectively, but did not affect the binding of fibrinogen to GPIIb/IIIa. Furthermore, Psm2 inhibited AktSer473 phosphorylation, but did not affect MAPK signaling and Src kinase activation. Molecular docking showed that Psm2 bound to phosphatidylinositol 3-kinase ß (PI3Kß) with a binding free energy of -13.265 kcal/mol. In addition, Psm2 did not cause toxicity in EA.hy926 cells and produced only slight bleeding in a mouse tail cutting model. CONCLUSION: Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling. Psm2 may be a lead compound or drug candidate that could be developed for the prevention or treatment of thrombotic diseases.

Mechanism-based inhibition of CYPs and RMs-induced hepatoxicity by rutaecarpine.

1. Rutaecarpine, a quinolone alkaloid isolated from the unripe fruit of Evodia rutaecarpa, is one of the main active components used in a variety of clinical applications, including the treatment of hypertension and arrhythmia. However, its hepatotoxicity has also been reported in recent years. 2. Reactive metabolites (RMs) play a vital role in drug-induced liver injury. Rutaecarpine has a secondary amine structure that may be activated to RMs. The aim of the study was to investigate the inhibition of rutaecarpine on CYPs and explore the possible relationship between RMs and potential hepatotoxicity. 3. A cell counting kit-8 cytotoxicity assay indicated that rutaecarpine can decrease the primary rat hepatocyte viability, increase lactate dehydrogenase and reactive oxygen species, reduce JC-1, and cause cell stress and membrane damage. The indexes were significantly restored by adding ABT, an inhibitor of CYPs. A cocktail assay showed that CYP1A2, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 can be inhibited by rutaecarpine in human liver microsomes. The IC50 values of CYP1A2 with and without NADPH were 2.2 and 7.4 µM, respectively, which presented a 3.3 shift. The results from a metabolic assay indicated that three mono-hydroxylated metabolites and two di-hydroxylated metabolites were identified and two GSH conjugates were also trapped. 4. Rutaecarpine can inhibit the activities of CYPs and exhibit a potential mechanism-based inhibition on CYP1A2. RMs may cause herb-drug interactions, providing important information for predicting drug-induced hepatotoxicity.

Frequency of and risk factors for oxcarbazepine-induced severe and symptomatic hyponatremia.

PURPOSE: Hyponatremia is one of the most common adverse effects in patients treated with oxcarbazepine (OXC). Most patients with OXC-induced hyponatremia are asymptomatic, so the presence of severe or symptomatic hyponatremia, which requires electrolyte correction or discontinuation of OXC therapy, has more important clinically implications. However, data for OXC-induced severe and symptomatic hyponatremia are limited. METHODS: We reviewed medical records of all patients with epilepsy who were treated with OXC at the Seoul National University Hospital. We analyzed serum sodium level results and attempted to identify correlations between various factors and the frequency of severe and symptomatic OXC-induced hyponatremia. RESULTS: Data from a total 1009 patient were examined. The frequency of severe and symptomatic hyponatremia was 11.1% and 6.8%, respectively. Multivariate analysis revealed that age (P=0.014, OR 1.014), antiepileptic drug (AED) polytherapy (P=0.040, OR 1.540), and the concomitant use of diuretics (P<0.001, OR 5.597) were independent risk factors for OXC-induced severe hyponatremia. Age (P=0.001, OR 1.034) and the concomitant use of diuretics (P=0.035, OR 2.222) were independent risk factors for OXC-induced symptomatic hyponatremia. The frequency of OXC-induced symptomatic hyponatremia that was judged to be clinically significant was 2.8% among the total OXC-treated epilepsy patients. CONCLUSION: Our study recommended that serum sodium be monitored regularly in patients taking OXC, especially in old age, AED polytherapy or concomitant use of diuretics, to assist in the early recognition of hyponatremia and to increase the awareness of symptoms that might be attributable to this.

Assessment of the in vitro and in vivo genotoxicity of extracts and indole monoterpene alkaloid from the roots of Galianthe thalictroides (Rubiaceae).

Roots of Galianthe thalictroides K. Schum. (Rubiaceae) are used in folk medicine in the State of Mato Grosso do Sul, Brazil, for treating and preventing cancer. To gain information about the genotoxicity of extracts (aqueous and EtOH), the CHCl3 phase resulting from partition of the EtOH extract and the indole monoterpene alkaloid 1 obtained from this plant. The genotoxicity of 1 and extracts was evaluated in vivo through the Drosophila melanogaster wing Somatic Mutation and Recombination Test - SMART, while in vitro cytotoxic (MTT) and Comet assays were performed only with alkaloid 1. The results obtained with the SMART test indicated that the aqueous extract had no genotoxic activity. The EtOH extract was not genotoxic to ST descendants but genotoxic to HB ones. The CHCl3 phase was genotoxic and cytotoxic. Alkaloid 1 showed significant mutational events with SMART, in the cytotoxicity assay (MTT), it showed a high cytotoxicity for human hepatoma cells (HepG2), whereas for the Comet assay, not showing genotoxic activity. The ethanol extract was shown to be genotoxic to HB descendants in the SMART assay, while the results obtained in this test for the monoterpene indole alkaloid 1 isolated from this extract.

A review of the anticancer potential of the antimalarial herbal cryptolepis sanguinolenta and its major alkaloid cryptolepine.

Cryptolepis sanguinolenta (Lindl.) Schltr (Periplocaceae), has a longstanding traditional use in the treatment of malaria in the West African region. Recent evidence suggests that the aqueous extract from the roots and the major alkaloid from the plant, cryptolepine, have prospects as cancer chemotherapeutic agents on account of their potent cytotoxicity to mammalian cells. Several mechanisms have been proposed to explain the cytotoxic activities of the agents. However, emerging evidence from their anti-inflammatory actions suggest that the mechanism of the cytotoxicity may be closely related to its anti-inflammatory activity. This review looks at the mechanisms of cryptolepis-induced cytotoxicity, its link with inflammation and its potential as anticancer agent. The elucidation of these interwoven mechanisms may be useful in the development of cryptolepine or other analogues as new anticancer agents.

Augmentation of cellular immune response by Ipomoea obscura and Ipobscurine alkaloid attenuates tumor growth in mice.

The immune status of the host plays a crucial role in controling the process of carcinogenesis. General or selective activation of various immunocompetent cells and their secretory function to maintain a healthy immune status may help in cancer prophylaxis, as well as therapy. The present study focused on the effect of Ipomoea obscura and Ipobscurine on cell-mediated immune response. In this study we evaluated the effect of I. obscura and an indole alkaloid fraction from I. obscura on effector mechanisms of cell-mediated immune response by analyzing cytotoxic T lymphocyte (CTL) activity, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and antibody-dependent complement-mediated cytotoxicity (ACC). The effect of I. obscura and Ipobscurine on interleukin-2 (IL-2) and interferon-γ (IFN-γ) levels was also analyzed. In the in vitro and in vivo systems, I. obscura and Ipobscurine treatment augmented cell-mediated immune response by enhancing the killing activity of CTL and NK cells from splenocytes in normal as well as tumor-bearing mice. ADCC and ACC were also enhanced significantly in both normal and tumor-bearing animals after drug administration, compared with untreated control. Administration of I. obscura and Ipobscurine significantly enhanced the production of IL-2 and IFN-γ in normal as well as tumor-bearing animals. This study reveals that both I. obscura and Ipobscurine have the potential to augment immune response through the enhanced secretion of IL-2 and IFN-γ by T cells and thereby inhibit tumor growth and as an alternative medicine for cancer treatment.

Efeito dos ácidos naftaleno acético e indolilbutírico no enraizamento de estacas de jambolão [Syzygium cumini (L. ) Skeels] / Effect of naphthaleneacetic acid and indolebutyric acid on rooting of jambul [Syzygium cumini (L. ) Skeels] cuttings

O jambolão propaga-se normalmente por sementes o que acarreta variabilidade nas plantas descendentes e um problema quando o objetivo é a formação de pomar comercial. O desenvolvimento de protocolo de propagação vegetativa por meio da estaquia possibilitaria a reprodução de todas as características da planta matriz, uniformidade nas populações e facilidade de propagação. O presente trabalho teve por objetivo avaliar o efeito dos ácidos naftaleno acético (ANA) e indolilbutírico (AIB) no enraizamento de estacas de jambolão. Estacas da região mediana dos ramos foram confeccionadas com 12 cm de comprimento, cortadas em bisel na base e reto acima da última gema axilar, mantendo-se um par de folhas reduzidas à metade. As bases das estacas foram imersas por 10 segundos em soluções aquosas contendo ANA ou AIB nas concentrações de 0, 500, 1.000 e 1.500 mg L-1. Para o plantio foram utilizadas bandejas plásticas contendo areia de granulometria média. As estacas foram mantidas em casa-de-vegetação com nebulização intermitente e após 120 dias do plantio, foram avaliadas as variáveis: porcentagem de estacas enraizadas, com calos, vivas (não enraizadas e sem calos) e mortas, comprimento das três maiores raízes (cm) e número de raízes formadas por estaca. Os melhores resultados de enraizamento foram verificados com 1.000 mg L-1 para ambos os fitorreguladores testados. A porcentagem de enraizamento foi ligeiramente superior com a utilização de ANA quando comparada ao AIB.

Jambul usually propagates by seeds, which causes variability in the descendant plants and represents a problem in the formation of commercial orchards. The development of a protocol for vegetative propagation by cuttings would enable the reproduction of all features of the Mother plant, uniformity in populations and easy propagation. The aim of this work was to evaluate the effect of naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) on rooting of jambul cuttings. Twelve-cm-long cuttings from the median region of branches were prepared through bevel cut in the base and right cut above the last axillary bud, keeping one pair of halved leaves. Cutting bases were immersed for 10s in aqueous solutions containing NAA or IBA at 0, 500, 1000 and 1500 mg L-1 concentrations. Plastic trays containing medium sand were used in the planting. The cuttings were kept in a greenhouse under intermittent nebulization and, at 120 days after planting, the following variables were evaluated: percentage of rooted, with calluses, alive (not-rooted and without calluses) and dead cuttings; length of the three largest roots (cm); and number of roots per cutting. The best rooting was observed by using 1000 mg L-1 of both tested plant growth regulators. Rooting percentage was slightly higher under NAA relative to IBA.

Anti-inflammatory properties of cryptolepine.

Cryptolepine is the major alkaloid of the West African shrub, Cryptolepis sanguinolenta. Cryptolepine has been shown to inhibit nitric oxide production, and DNA binding of Nuclear Factor-kappa B following inflammatory stimuli in vitro. In order to validate the anti-inflammatory property of this compound in vivo, we investigated its effects on a number of animal models of inflammation. Cryptolepine (10-40 mg/kg i.p.) produced significant dose-dependent inhibition of the carrageenan-induced rat paw oedema, and carrageenan-induced pleurisy in rats. These effects were compared with those of the non-steroidal anti-inflammatory drug indomethacin (10 mg/kg). At doses of 10-40 mg/kg i.p., cryptolepine inhibited lipopolysaccharide (LPS)-induced microvascular permeability in mice in a dose-related fashion. Oral administration of up to 40 mg/kg of the compound for four consecutive days did not induce gastric lesion formation in rats. Analgesic activity was also exhibited by cryptolepine through a dose-related (10-40 mg/kg i.p.) inhibition of writhing induced by i.p. administration of acetic acid in mice. The results of this study reveal that cryptolepine possesses in vivo anti-inflammatory activity.

Effects of isorhynchophylline on angiotensin II-induced proliferation in rat vascular smooth muscle cells.

Proliferation of vascular smooth muscle cells (VSMCs) is a crucial event in cardiovascular diseases. Isorhynchophylline, an alkaloid from a traditional Chinese medicine Gambirplant, has been used to treat cardiovascular diseases. The aim of this study was to investigate the effects of isorhynchophylline on angiotensin II (Ang II)-induced proliferation of rat VSMCs. VSMCs were isolated from rat artery and cultured for 14 days before experimentation. The effect of isorhynchophylline on Ang II-induced proliferation was evaluated by cell number, MTT assay and flow cytometry, and nitric oxide (NO) content and activity of NO synthase (NOS) were measured. The expression of proto-oncogene c-fos, osteopontin (OPN) and proliferating cell nuclear antigen (PCNA) mRNAs was measured by real-time RT-PCR. VSMC cultures were verified by morphology and immunostaining with alpha-smooth muscle actin. Isorhynchophylline (0.1-10.0 microM) was not toxic to VSMCs, but markedly decreased Ang II (1.0 microM)-enhanced cell number and MTT intensity, and blocked cell transition from G(0)/G(1) to S phase. Furthermore, isorhynchophylline increased the NO content and NOS activity, and suppressed Ang II-induced over-expression of c-fos, OPN and PCNA. Thus, isorhynchophylline was effective against Ang-II induced cell proliferation, an effect that appears to be due, at least in part, to increased NO production, regulation of the cell cycle, and depressed expression of c-fos, OPN and PCNA related to VMSC proliferation.

New anti-mitotic drugs with distinct anti-calmodulin activity.

Bisindole Vinca alkaloids target microtubule system causing anti-mitotic activity. The problem of their clinical application is the lack of selectivity resulting in toxic side effects. In this paper we review the late history of new bisindole derivatives focusing on KARs recognized as potent anti-cancer drugs with low side effect. KARs, just as other bisindoles, impede microtubule assembly of mitotic spindle, however, they display no anti-calmodulin activity. This new drug family appears to be less potent than vinblastine in vitro systems, but it shows high antitumor efficacy with considerably higher doses being well tolerated in the animal tumor models. 3D data of calmodulin complexed with KAR-2 explain the specificity and unique pharmacology of KAR derivatives.