Anti-thrombotic effects of higenamine

Epigenetic compounds targeting pharmacological target lysine specific demethylase 1 and its impact on immunotherapy, chemotherapy and radiotherapy for treatment of tumor recurrence and resistance

It has been proven that metastatic recurrence and therapeutic resistance are linked. Due to the variability of individuals and tumors, as well as the tumor's versatility in avoiding therapies, therapy resistance is more difficult to treat. Therapy resistance has significantly restricted the clinical feasibility and efficacy of tumor therapy, despite the discovery of novel compounds and therapy combinations with increasing efficacy. In several tumors, lysine specific demethylase 1 (LSD1) has been associated to metastatic recurrence and therapeutic resistance. For researchers to better comprehend how LSD1-mediated tumor therapy resistance occurs and how to overcome it in various tumors, this study focused on the role of LSD1 in tumor recurrence and therapeutic resistance. The importance of therapeutically targeted LSD1 was also discussed. Most gene pathway signatures are related to LSD1 inhibitor sensitivity. However, some gene pathway signatures, especially in AML, negatively correlate with LSD1 inhibitor sensitivity, but targeting LSD1 makes the therapy-resistant tumor sensitive to physiological doses of conventional therapy. We propose that combining LSD1 inhibitor with traditional tumor therapy can help patients attain a complete response and prevent cancer relapse.

Pharmacological effects of higenamine based on signalling pathways and mechanism of action

Higenamine (HG) is a chemical compound found in various plants, such as aconite. Recent pharmacological studies have demonstrated its effectiveness in the management of many diseases. Several mechanisms of action of HG have been proposed; however, they have not yet been classified. This review summarises the signalling pathways and pharmacological targets of HG, focusing on its potential as a naturally extracted drug. Articles related to the pharmacological effects, signalling pathways and pharmacological targets of HG were selected by searching the keyword "Higenamine" in the PubMed, Web of Science and Google Scholar databases without limiting the search by publication years. HG possesses anti-oxidant, anti-apoptotic, anti-inflammatory, electrophysiology regulatory, anti-fibrotic and lipid-lowering activities. It is a structural analogue of catecholamines and possesses characteristics similar to those of adrenergic receptor ligands. It can modulate multiple targets, including anti-inflammation- and anti-apoptosis-related targets and some transcription factors, which directly or indirectly influence the disease course. Other naturally occurring compounds, such as cucurbitacin B (Cu B) and 6-gingerol (6-GR), can be combined with HG to enhance its anti-apoptotic activity. Although significant research progress has been made, follow-up pharmacological studies are required to determine the exact mechanism of action, new signalling pathways and targets of HG and the effects of using it in combination with other drugs.

Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

Processed aconite root (PA), the tuberous root of Aconitum carmichaelii prepared by autoclaving, is a crude drug used in Japanese traditional Kampo medicine and traditional Chinese medicine for the symptoms of kidney deficiency, that is related to the muscle atrophy in modern medicine. The objective of the present study is to evaluate the effectiveness of PA on muscle atrophy and to find its active ingredients using dexamethasone-induced muscle ring finger protein-1 (MuRF1) mRNA expression in murine myoblast C2C12 cells. Dexamethasone-induced MuRF1 expression was significantly suppressed by methanol-soluble part of boiling water extract of PA in a concentration-dependent manner with its IC₅₀ value of 1.5 mg/ml. By the activity-guided fractionations of PA extract using the partition between organic solvents and its aqueous solution, the activity of PA did not transfer into the fraction containing aconitine-type diterpenoid alkaloids but into BuOH layer. Then, we found higenamine and salsolinol as the active ingredients in PA. Higenamine and salsolinol significantly suppressed dexamethasone-induced MuRF1 expression, and their IC₅₀ values were 0.49 and 50 µM, respectively. The contents of higenamine and salsolinol in the decoctions of commercially available fourteen PA products are 0.12 and 14 µg/ml as the average values, and varied with the coefficient of variation (CV) values of 97 and 63%, respectively. Higenamine also significantly suppressed dexamethasone-induced mRNA expressions of muscle atrophy F-box protein (MAFbx)/atrogin1, casitas B-lineage lymphoma-b (Cbl-b), troponin, branched-chain amino acid aminotransferase 2 (BCAT2), and Bcl-2 binding and pro-apoptotic protein3 (Bnip3). Although the quality control of PA is regulated by the contents of diterpene alkaloids, salsolinol and higenamine can be used as the marker compounds to certificate the pharmacological activities of PA.

Effects of the Higenamine, a Potent Compound from Aconitum, on UVB-Induced Photoaging in Hairless Mice

Aim

Higenamine [1-[(4-hydroxyphenyl) methyl]-1, 2, 3, 4-tetrahydroisoquinoline-6, 7-diol], a potent cardiotonic compound from Aconitum, contributes to vascular relaxation and bronchodilation. However, the effects and mechanisms of action of higenamine on skin aging remain poorly understood. In this study, the effects of higenamine on UVB-induced photoaging were examined in the hairless mouse model.

Methods

The dorsal skin of hairless mice (CrlOri : SKH1) was exposed to chronic UVB irradiation (100–300 mJ/cm² for 6 weeks), with subsequent administration of higenamine (1–20 mg/kg, p.o.) for 2 weeks. TGF-β, Smad3 DNA-binding phosphorylation, and COL1A1 levels were analyzed by immunohistochemistry, and histological analysis of the skin was performed via H&E and MT staining.

Results

Higenamine increased TGF-β, Smad3 DNA-binding phosphorylation, and COL1A1 expression in primary human fibroblast cells and mouse skin. Higenamine suppressed UVB-induced photoaging via skin recovery, improved epidermal thickness, and prevented Smad3, DNA-binding phosphorylation, and COL1A1 depletion via TGF-β signaling.

Conclusion

Higenamine enhances collagen production in the skin through TGF-β/Smad3 signaling and potentially suppresses UVB-induced skin aging.

Dietary Supplements as Source of Unintentional Doping

Background

The substances used in sport could be divided into two major groups: those banned by the World Anti-Doping Agency and those which are not. The prohibited list is extremely detailed and includes a wide variety of both medicinal and nonmedicinal substances. Professional athletes are exposed to intense physical overload every day. They follow a relevant food regime and take specific dietary supplements, which is essential for the better recovery between trainings and competitions. However, the use of “nonprohibited” dietary supplements (DS) is not always completely safe. One of the risks associated with the use of dietary supplements is the risk of unintended doping—originating from contaminated products. The presence of undeclared compounds in the composition of DS is a serious concern. The aim of this study is to evaluate the risk of unintentional doping.

Materials and Methods

Literature search was done through PubMed, Science Direct, Google Scholar, and Web of Science. Studies investigating the presence of undeclared compounds, in dietary supplements, banned by WADA met the inclusion criteria. The last search was conducted in June 2021. The present review is based on a total of 50 studies, which investigated the presence of undeclared compounds in DS.

Results

The total number of analyzed DS is 3132, 875 of which were found to contain undeclared substances. Most frequently found undeclared substances are sibutramine and anabolic-androgenic steroids.

Conclusion

More than 28% of the analyzed dietary supplements pose a potential risk of unintentional doping. Athletes and their teams need to be aware of the issues associated with the use of DS. They should take great care before inclusion of DS in the supplementation regime.

Higenamine in Plants as a Source of Unintentional Doping

BACKGROUND

Higenamine is a β2 agonist of plant origin. The compound has been included in WADA's prohibited list since 2017. Higenamine may be detected in different plants and many food supplements of natural origin.

METHODS

Our literature search was conducted through PubMed, Science Direct, Google Scholar, and Web of Science studies investigating the presence of higenamine in plants that are used in traditional folk medicine or included in food supplements. Our study aimed to assess the risk of adverse analytical findings caused by higenamine-containing plants.

RESULTS

Based on our literature search, Nelumbo nucifera, Tinospora crispa, Nandina domestica, Gnetum parvifolium, Asarum siebodii,Asarum heterotropoides, Aconitum carmichaelii, and Aristolochia brasiliensis are higenamine-containing plants. Based on data from Eastern folk medicine, these plants can provide numerous health benefits. Professional athletes likely ingest these plants without knowing that they contain higenamine; these herbs are used in treatments for different conditions and various foods/food supplements in addition to folk medicine.

CONCLUSION

Athletes and their teams must be aware of the issues associated with the use of plant-based products. They should avoid consuming higenamine-containing plants during and outside of competition periods.

Annual review of lysine-specific demethylase 1 (LSD1/KDM1A) inhibitors in 2021

Lysine-specific demethylase 1 (LSD1/KDM1A) has emerged as a promising epigenetic target for disease treatment. Several LSD1 inhibitors have advanced into clinical trials. Following our last annual review on LSD1 inhibitors in 2020 (Eur. J. Med. Chem. 2021, 214, 113254), in this review we aim to update LSD1 inhibitors including natural products, synthetic compounds and cyclic peptides reported during 2021. Design strategies, structure-activity relationships, binding model analysis and modes of action are highlighted. In particular, two FDA-approved antihypertensive drugs raloxifene and fenoldopam were repurposed as reversible LSD1 inhibitors. The clinical candidate TAK-418 for treating neurodevelopmental disorders and PET imaging agent [¹⁸F]30 for LSD1 were identified. Moreover, dual inhibitors targeting both LSD1 and HDAC6 or tubulin displayed enhanced anti-cancer effects than single agents. These compounds further enrich the structural types of LSD1 inhibitors.

The modulation of SIRT1 and SIRT3 by natural compounds as a therapeutic target in doxorubicin-induced cardiotoxicity: A review

Doxorubicin (DOX) is a potent antitumor agent with a broad spectrum of activity; however, irreversible cardiotoxicity resulting from DOX treatment is a major issue that limits its therapeutic use. Sirtuins (SIRTs) play an essential role in several physiological and pathological processes including oxidative stress, apoptosis, and inflammation. It has been reported that SIRT1 and SIRT3 can act as a protective molecular against DOX-induced myocardial injury through targeting numerous signaling pathways. Several natural compounds (NCs), such as resveratrol, sesamin, and berberine, with antioxidative, anti-inflammation, and antiapoptotic effects were evaluated for their potential to suppress the cardiotoxicity induced by DOX via targeting SIRT1 and SIRT3. Numerous NCs exerted their therapeutic effects on DOX-mediated cardiac damage via targeting different signaling pathways, including SIRT1/LKB1/AMPK, SIRT1/PGC-1α, SIRT1/NLRP3, and SIRT3/FoxO. SIRT3 also ameliorates cardiotoxicity by enhancing mitochondrial fusion.

A systematic review of pharmacological activities, toxicological mechanisms and pharmacokinetic studies on Aconitum alkaloids

The tubers and roots of Aconitum (Ranunculaceae) are widely used as heart medicine or analgesic agents for the treatment of coronary heart disease, chronic heart failure, rheumatoid arthritis and neuropathic pain since ancient times. As a type of natural products mainly extracted from Aconitum plants, Aconitum alkaloids have complex chemical structures and exert remarkable biological activity, which are mainly responsible for significant effects of Aconitum plants. The present review is to summarize the progress of the pharmacological, toxicological, and pharmacokinetic studies of Aconitum alkaloids, so as to provide evidence for better clinical application. Research data concerning pharmacological, toxicological and pharmacokinetic studies of Aconitum alkaloids were collected from different scientific databases (PubMed, CNKI, Google Scholar, Baidu Scholar, and Web of Science) using the phrase Aconitum alkaloids, as well as generic synonyms. Aconitum alkaloids are both bioactive compounds and toxic ingredients in Aconitum plants. They produce a wide range of pharmacological activities, including protecting the cardiovascular system, nervous system, and immune system and anti-cancer effects. Notably, Aconitum alkaloids also exert strong cardiac toxicity, neurotoxicity and liver toxicity, which are supported by clinical studies. Finally, pharmacokinetic studies indicated that cytochrome P450 proteins (CYPs) and efflux transporters (ETs) are closely related to the low bioavailability of Aconitum alkaloids and play an important role in their metabolism and detoxification in vivo.

Discovery of higenamine as a potent, selective and cellular active natural LSD1 inhibitor for MLL-rearranged leukemia therapy

Natural products are a rich source of lead compounds and have shown promise for epigenetic drug discovery. In this work, we discovered higenamine from our natural product library as a potent, selective and cellular active natural LSD1 inhibitor. Higenamine shows acceptable potency against LSD1 and high selectivity towards LSD1 over MAOA/B. Higenamine significantly increases expression of LSD1 substrates H3K4me1 and H3K4me2 in MLL-rearranged leukemia cells MV4-11 and MOLM-13, but nearly had no effect on LSD1 and H3K4Me3. Meanwhile, higenamine dose-dependently suppresses the levels of HOXA9 and MEIS1 that are overexpressed in leukemia cell lines. Notably, higenamine induces cell differentiation of MV4-11 and MOLM-13 cells accompanying by increased expression of CD11b, CD14 and CD86. Higenamine promotes cell apoptosis, inhibits colony formation, but does not inhibit proliferation of leukemia cells significantly. In addition, the expression levels of p53 are dramatically changed by higenamine in an LSD1-dependent manner in MV4-11 cells. Taken together, higenamine could be employed as a starting point for the development of more selective and potent LSD1 inhibitors. Our work firstly reveals the non-classical epigenetic regulation mechanism of higenamine in cancers, and also demonstrates the efficacy of higenamine for MLL-rearranged leukemia therapy.

Interaction between Traditional Chinese Medicine and Anticoagulant/Antiplatelet Drugs

Background:

Traditional Chinese medicine (TCM) has been used for medical purposes since the ancient time and has gradually gained recognition worldwide. Nowadays, patients with thrombus presiding to anticoagulant/ antiplatelet drugs prefer taking TCM. However, an increasing number of studies on herb–drug interactions have been shown. Nevertheless, findings are frequently conflicting and vague. In this review, we discuss the herb–drug interactions between TCM and anticoagulant/antiplatelet drugs to provide guidance on concomitant ingestion with anticoagulant/antiplatelet drugs.

Methods:

We undertook a structured search of medicine and drug databases for peer-reviewed literature using focused review questions.

Results:

Danshen, Ginkgo, Ginger, H. Perforatum, SMY and Puerarin injection had directional regulation effects on the efficacy of anticoagulant drugs by altering the CYPs, pharmacokinetic indexs and hemorheological parameters. H. Perforatum inhibited the efficacy of Clopidogrel by enhancing the CYP3A4 activity and Ginkgo increased the efficacy of Ticlopidine. Additionally, Renshen, the formulae except SMY and injections except Puerarin injection could increase or decrease the efficacy of anticoagulant/antiplatelet drugs via regulating the CYPs, platelet aggregation, hemorheological parameters and others.

Conclusion:

Some cases have reported that TCMs may increase the bleeding risk or has no effect on coagulation when anticoagulant/antiplatelet drugs are concurrently used. However, pharmacokinetic studies have presented either consistent or slightly varying results. So it is difficult to ascertain whether the concurrent use of TCM may increase or reduce the pharmacologic effects of anticoagulant/antiplatelet drugs with adverse reactions. Therefore, herb–drug interactions of TCM and anticoagulant/antiplatelet drugs should be further explored and defined.

Efficacy and safety of Shenfu injection for patients with return of spontaneous circulation after sudden cardiac arrest: Protocol for a systematic review and meta-analysis

BACKGROUND

Sudden cardiac arrest (SCA) is one of the most common critical illnesses encountered in clinical practice. Shenfu injection (SFI) has received extensive attention as an alternative therapy that can effectively maintain the autonomic circulation function after cardiopulmonary resuscitation. However, the mechanism of SFI is not yet fully understood. In addition, there has been no systematic review or meta-analysis of SFI in the treatment of patients with return of spontaneous circulation after SCA. Herein, we describe the protocol of a proposed study based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines that aims to systematically evaluate the efficacy and safety of SFI in patients with return of spontaneous circulation after SCA.

METHODS

Two researchers will search 9 electronic databases (PubMed, Medline, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese VIP Information, Wanfang, and Chinese Biomedical Database) to identify all studies that meet the inclusion criteria and were published before July 2018. After information extraction and methodological quality evaluation, we will use Stata 13.0 software (STATA Corporation, College Station, TX, USA) to synthesize the data. The primary outcomes will be the survival rate and Glasgow Coma Scale.

RESULTS

The data synthesis results will objectively illustrate the efficacy and safety of SFI in patients with return of spontaneous circulation after SCA.

CONCLUSION

The findings will provide a reference for the use of SFI in the treatment of patients with return of spontaneous circulation after SCA.

REGISTRATION

PROSPERO (registration number: CRD42018104230).

Involvement of UDP-glucuronosyltransferases in higenamine glucuronidation and the gender and species differences in liver

OBJECTIVES

Higenamine (HG), an active ingredient of Aconite root in Chinese herbal medicine, is mainly metabolized by UDP-glucuronosyltransferases (UGT). However, the systematic glucuronidation of HG in humans remains unclear. The purpose of this study was to investigate the glucuronidation of HG.

METHODS

12 recombinant human UGT (rUGT) isozymes were used to characterize the HG glucuronidation. Liver microsomes from male and female mice, rats, guinea pigs, dogs, and humans were used to determine the species and gender differences using liquid chromatography-mass spectrometry.

KEY FINDINGS

One monoglucuronide was detected in reactions catalyzed by rUGT1A6, rUGT1A8, rUGT1A9, also human and dog liver microsomes. UGT1A9 is the most important glucuronosyltransferase that metabolizes HG. Because carvacrol, a specific inhibitor of UGT1A9, can significantly decrease the glucuronidation of HG in Human liver microsomes and UGT1A9. HG metabolism by UGT1A9 described in Michaelis-Menten kinetics (K_m=15.4 mM,V_max=2.2 nmol/mg/min) and glucuronidation in liver microsomes were species dependent. Gender did not affect the kinetic parameters among species except in rats.

CONCLUSIONS

UGT1A9 is a major isoenzyme responsible for the glucuronidation of HG in Human liver microsomes (HLMs). Dog may be an appropriate animal model to evaluate HG metabolism.

Changes in Cardiac Function After a Single Intravenous Administration of CKD-712 in Healthy Male Volunteers

BACKGROUND AND OBJECTIVES

CKD-712, a candidate treatment for septic shock, acts by increasing cardiac output. This study investigated changes in the pharmacodynamics, pharmacokinetics, and tolerability of CKD-712 after a single intravenous administration.

METHODS

A dose-block-randomized, double-blind, placebo-controlled, single-dose escalation study was conducted in 44 healthy subjects receiving 20, 40, 80, 160, 240, or 320 μg/kg CKD-712 or placebo. Pharmacodynamics were evaluated using computerized impedance cardiography, vital signs, platelet aggregation, and bleeding time. Serial blood and urine samples for pharmacokinetic analysis were collected up to 12 and 24 h, respectively, after the initiation of intravenous drug infusion. Tolerability assessments were performed throughout the study.

RESULTS

The area under the effect-time curve of the cardiac index (AUEC_CI) and systolic blood pressure (AUEC_SBP) changed significantly with the 160 and 320 µg/kg doses of CKD-712 compared with placebo. Furthermore, the AUEC_CI and AUEC_SBP tended to increase as the systemic exposure of CKD-712 increased from 20 to 240 µg/kg. The frequency of drug-related adverse events (AEs), including cardiovascular symptoms, was higher with the 320 µg/kg dose.

CONCLUSION

The pharmacological effects and on-target AEs of CKD-712 increased relative to the dose increments. The results of this study suggest that potentially therapeutic doses of CKD-712 could range from 160 to 240 μg/kg.

Applications of Higenamine in pharmacology and medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitum has been used as local and traditional medicines in many asian regions for the treatment of various diseases such as collapse, syncope, painful joints, oedema, bronchial asthma et al. Higenamine, a plant-based alkaloid, was initially isolated from Aconitum and identified as the active cardiotonic component of Aconitum. It has been tested as a candidate of pharmacologic stress agent in the detection of coronary artery diseases (CADs) and now researchers have just accomplished the phase III clinical studies successfully in China. Besides, a large number of studies have revealed the various pharmacological properties and potentially multi-spectral medical applications of higenamine. However, to date, no comprehensive review on higenamine has been published.

AIM OF THE REVIEW

This present paper aims to compile a comprehensive update regarding the biochemistry, pharmacokinetic features, pharmacological activities, clinical and potential clinical uses and toxicities on higenamine with the ultimate objective of providing a guide for future research on this drug.

MATERIALS AND METHODS

The selection of relevant data was made through a search using the keyword "higenamine" in "Web of science", "Pubmed", and "China Knowledge Resource Integrated (CNKI)". Information was also acquired from local classic herbal literature, government reports and conference papers.

RESULTS

In addition to Aconitum, higenamine also exists in many other plants including Tinospora crispa, Nandina domestica T_HUNBERG, Gnetum Parvifolium C.Y. Cheng, sarum Heterotropoides_,Nelumbo nucifera_,N.nucifera. The pharmacokinetic studies conducted in animals and humans showed that higenamine conformed to a two-compartment pharmacokinetic model. Studies over the last four decades on higenamine have revealed its various pharmacological properties such as positive inotropic and chronotropic effect, activating slow channel effect, vascular and tracheal relaxation effect, anti-thrombotic, anti-apoptotic and anti-oxidative effect, anti-inflammatory and immunomodulatory effect. This phytochemical constituent has shown its potential therapeutic effects for diseases like heart failure, disseminated intravascular coagulation (DIC), shock, arthritis, asthma, ischemia/reperfusion (I/R) injuries and erectile dysfunction.

CONCLUSIONS

Extensive basic and clinical studies on higenamine showed valuable therapeutic effects on different disorders. However, the underlying mechanisms of higenamine have not been established. Therefore, the safety, tolerability and efficacy of higenamine are as yet, not fully understood. Additionally, some of the studies were small sample-sized and unreliable. To sum up, there is a need for deeper investigation in the mechanisms of higenamine action, as well as well-designed preclinical and clinical trials studies to test the safety and clinical value of the drug.

Occurrence of Enantioselectivity in Nature: The Case of (S)-Norcoclaurine

This review article is aimed at providing a monographic overview on (S)-norcoclaurine (NC) alkaloid from three diverse points of view, collected all together for the first time: 1) the synthetic one, where the compound is seen as a target chiral molecule to be obtained in the highest optical purity and as a starting point for the development of biocatalytic asymmetric syntheses of tetrahydroisoquinoline alkaloids; 2) the chromatographic one, which addresses the HPLC separation of the two NC enantiomers; and 3) the biochemical one, for which a thorough understanding of the topology and mechanism of action of norcoclaurine synthase (NCS) enzyme is still a matter of debate. Special emphasis on the most recent studies in the field is given by discussing the results published by the main research groups who are working on NC and NCS.

Clinical safety assessment of oral higenamine supplementation in healthy, young men

OBJECTIVE

Higenamine, an herbal agent also known as norcoclaurine, is thought to stimulate β-androgenic receptors and possess lipolytic activity. It is currently making its way into the dietary supplement market. To our knowledge, no studies have been conducted to determine the safety profile of oral higenamine when used alone and in conjunction with other commonly used lipolytic agents.

METHODS

Forty-eight men were assigned to ingest either a placebo, higenamine, caffeine, or higenamine + caffeine + yohimbe bark extract daily for a period of 8 weeks. Before and after 4 and 8 weeks of supplementation, the following variables were measured: resting respiratory rate, heart rate, blood pressure, urinalysis, complete blood count, metabolic panel, liver enzyme activity, and lipid panel.

RESULTS

No interaction effects were noted for any variable (p > 0.05), with no changes of statistical significance occurring across time for any of the four conditions (p > 0.05).

CONCLUSION

This is the first study to determine the safety profile of oral higenamine intake in human subjects. Our data indicate that 8 weeks of daily higenamine supplementation, either alone or in conjunction with caffeine and yohimbe bark extract, does not result in a statistically significant change in any of the measured outcome variables. Additional studies, inclusive of a larger sample size, are needed to extend these initial findings.

Influence of racemic higenamine on the sinus node

The aim of this study was to explore the mechanism of racemic higenamine in the treatment of sick sinus syndrome (SSS). A total of 40 New Zealand rabbits were randomly divided into normal sinus node and damaged sinus node (SND) groups, and each group was randomly divided into treatment and control groups (n=10). The SND model was established by formaldehyde wet dressing of the sinus node area. The treatment groups were administered an intravenous infusion of 0.04 mg/kg racemic higenamine via the marginal ear vein within 5 min. The electrophysiological indicators of sinoatrial function, including the sinus node recovery time (SNRT), corrected sinus node recovery time (CSNRT), total sinoatrial conduction time (TSACT) and sinus cycle length (SCL), were determined before and 20 min after medication and the changes in these indicators were evaluated. The two control groups were administered 10 ml physiological saline. Following the administration of racemic higenamine, the SNRT, CSNRT, TSACT and SCL in the normal sinus node and SND groups were significantly shortened compared with those in the control groups (P<0.01). The electrophysiological influence of racemic higenamine on sinoatrial function in the SND group was significantly greater than that in the normal sinus node group (P<0.01), and its effect in the treatment of arrhythmia caused by a damaged sinus node was statistically significant (P<0.05). The main electrophysiological mechanism of racemic higenamine in the treatment of SSS was the enhancement of sinus node self-discipline and improvement of sinoatrial and atrioventricular conduction function.

A phase I study on pharmacokinetics and pharmacodynamics of higenamine in healthy Chinese subjects

AIM

To investigate the pharmacokinetics, pharmacodynamics, and safety of higenamine, an active ingredient of Aconite root, in healthy Chinese volunteers.

METHODS

Ten subjects received continuous, intravenous infusion of higenamine at gradually escalating doses from 0.5 to 4.0 μg·kg(-1)·min(-1), each dose was given for 3 min. Blood and urine samples were collected at designated time points to measure the concentrations of higenamine. Pharmacodynamics was assessed by measuring the subject's heart rate. A nonlinear mixed-effect modeling approach, using the software Phoenix NLME, was used to model the plasma concentration-time profiles and heart rate.

RESULTS

Peak concentrations (C(max)) of higenamine ranged from 15.1 to 44.0 ng/mL. The half-life of higenamine was 0.133 h (range, 0.107-0.166 h), while the area under concentration-time curve (AUC), extrapolated to infinity, was 5.39 ng·h·mL(-1) (range, 3.2-6.8 ng·h·mL(-1)). The volume of distribution (V) was 48 L (range, 30.8-80.6 L). The total clearance (CL) was 249 L/h (range, 199-336 L/h). Within 8 h, 9.3% (range, 4.6%-12.4%) of higenamine was recovered in the urine. The pharmacokinetics of higenamine was successfully described using a two-compartment model with nonlinear clearance. In the pharmacodynamic model, heart rates were related to the plasma drug concentrations using a simple direct effect model with baseline. The E(0), E(max), and EC(50) were 68 bpm, 73 bpm and 8.1 μg/L, respectively.

CONCLUSION

Higenamine has desirable pharmacokinetic and pharmacodynamic characteristics. The results provide important information for future clinical studies on higenamine.

Higenamine reduces HMGB1 during hypoxia-induced brain injury by induction of heme oxygenase-1 through PI3K/Akt/Nrf-2 signal pathways

Growing lines of evidence suggests that high mobility group box-1 (HMGB1) plays an important role for promoting inflammation and apoptosis in brain ischemia. Previously, we demonstrated that inducers of heme oxygenase-1 (HO-1) significantly reduce HMGB1 release in inflammatory conditions in vitro and in vivo. Thus, we tested our hypothesis that higenamine protects brain injury by inhibition of middle cerebral artery occlusion (MCAO)-mediated HMGB1 release in vivo, and glucose/glucose oxidase (GOX)-induced apoptosis in C6 cells in vitro due to HO-1 induction. Higenamine increased HO-1 expression in C6 cells in both hypoxia and normoxia, in which the former was much more significant than the latter. Higenamine increased Nrf-2 luciferase activity, translocated Nrf-2 to nucleus, and increased phosphorylation of Akt in C6 cells. Consistent with this, LY 294002, a PI3K inhibitor, inhibited HO-1 induction by higenamine and apoptosis induced by glucose/GOX in C6 cells was prevented by higenamine, which effect was reversed by LY 294002. Importantly, administration of higenamine (i.p) significantly reduced brain infarct size, mortality rate, MPO activity and tissue expression of HMGB1 in MCAO rats. In addition, recombinant high mobility group box 1 induced apoptosis in C6 cells by increasing ratio of Bax/bcl-2 and cleaved caspase c, which was inhibited by higenamine, and all of these effects were reversed by co-treatment with ZnPPIX. Therefore, we conclude that higenamine, at least in part, protects brain cells against hypoxic damages by up-regulation of HO-1. Thus, higenamine may be beneficial for the use of ischemic injuries such as stroke.

The relaxation effect and mechanism of action of higenamine in the rat corpus cavernosum

Higenamine mediates cardiotonic, vascular relaxation and bronchodilator effects. The relaxation effects and the mechanism of action of higenamine on the rat corpus cavernosum (CC) were assessed to investigate the effect of higenamine on penile erection. Strips of CC and aorta were used in organ baths for isometric tension studies. Tension was measured with isometric force transducers, and muscle relaxation was expressed as the percent decrease in precontraction induced by phenylephrine (PE). The relaxation reactions were investigated in an endothelial-denuded group and groups pretreated with N(G)-nitro-L-arginine methyl ester (NO synthesis inhibitor), propranolol (β-receptor blocker), indomethacin (COX inhibitor), glibenclamide (K(+)(ATP) channel inhibitor), 4-aminopyridine (membrane potential-dependent potassium channel inhibitor) and methylene blue (guanylyl cyclase inhibitor) for 30 min. Intracavernous pressure (ICP) was assessed in rats after the intravenous administration of higenamine, and changes in guanosine 3',5'-cyclic monophosphate and adenosine 3',5'-cyclic monophosphate (cAMP) concentrations were measured on the basis of the higenamine concentration. Also, the combined reaction of higenamine and the phosphodiesterase type-5 (PDE-5) inhibitors was assessed. Higenamine induced relaxation of the CC and the aortic strips precontracted with PE in a dose-dependent manner. The CC was significantly more relaxed than the aortic rings in response to the same higenamine concentration (P<0.05). The CC relaxation reaction was suppressed by the β-receptor blocker propranolol. The cAMP concentration increased gradually with increased higenamine concentration (P<0.05). The ICP also increased with increased higenamine concentration in vivo (P<0.05). In the group pretreated with 10(-7) M higenamine, the relaxation reaction of CC induced by the PDE-5 inhibitor increased significantly, compared with CC exposed to the PDE-5 inhibitor but not pretreated with higenamine (P<0.05). In conclusion, higenamine induced relaxation of the rat CC in a dose-dependent manner. The effect may be mediated through β-adrenoceptors. The results suggest that higenamine may be valuable as a new lead compound for treating erectile dysfunction.

Biphasic tracheal relaxation induced by higenamine and nantenine from Nandina domestica Thunberg

We compared the effects of the extract from fruits of Nandina domestica Thunberg (NDE) and its constituents, higenamine and nantenine, on contractile responses in isolated guinea-pig trachea. NDE (1 mg/ml) caused biphasic relaxation of the trachea precontracted with high-K(+) stimulation: the fast component was blocked by propranolol and mimicked by higenamine; and the slow was resistant to propranolol and mimicked by nantenine. Ca(2+)-induced contraction under high-K(+) stimulation was antagonized by nantenine or NDE + propranolol. These results suggest that NDE relaxes the trachea quickly through β-adrenoceptor stimulation by higenamine and slowly through Ca(2+) antagonism by nantenine.

Norcoclaurine synthase: mechanism of an enantioselective pictet-spengler catalyzing enzyme

The use of bifunctional catalysts in organic synthesis finds inspiration in the selectivity of enzymatic catalysis which arises from the specific interactions between basic and acidic amino acid residues and the substrate itself in order to stabilize developing charges in the transition state. Many enzymes act as bifunctional catalysts using amino acid residues at the active site as Lewis acids and Lewis bases to modify the substrate as required for the given transformation. They bear a clear advantage over non-biological methods for their ability to tackle problems related to the synthesis of enantiopure compounds as chiral building blocks for drugs and agrochemicals. Moreover, enzymatic synthesis may offer the advantage of a clean and green synthetic process in the absence of organic solvents and metal catalysts. In this work the reaction mechanism of norcoclaurine synthase is described. This enzyme catalyzes the Pictet-Spengler condensation of dopamine with 4-hydroxyphenylacetaldehyde (4-HPAA) to yield the benzylisoquinoline alkaloids central precursor, (S)-norcoclaurine. Kinetic and crystallographic data suggest that the reaction mechanism occurs according to a typical bifunctional catalytic process.

Effects of higenamine and its 1-naphthyl analogs, YS-49 and YS-51, on platelet TXA2 synthesis and aggregation

The effects of higenamine and its 1-naphthyl analogs, YS-49 and YS-51, on thromboxane A(2) (TXA(2)) formation from arachidonic acid (AA) and aggregation in platelets, were investigated. YS-49 and YS-51 (IC(50); 32.8 and 39.4 microM respectively) exhibited much stronger inhibitory effects on TXA(2) formation than higenamine (IC(50); 2.99 mM). The higher inhibitory potencies of YS-49 and YS-51 (IC(50): 3.3 and 5.7 microM respectively) than higenamine (IC(50): 140 microM) on AA induced rat platelet aggregation was presumed to be the result of low inhibitory effect of higenamine than YS-49 and YS-51 on TXA(2) production from AA. Among the present three compounds, the more hydrophobic naphthylmethyl groups were supposed to be more favorable than p-hydroxybenzyl moiety, at 1-position of the tetrahydroisoquinoline ring, to display the inhibitory effects on TXA(2) production and AA induced aggregation of platelets. In addition, higenamine, YS-49 and YS-51 were observed directly antagonistic on TXA(2) receptor (TP receptors) by displaying inhibitory effects to U46619 (TXA(2) mimetic) induced platelet aggregation, however all of the three compounds showed similar order of inhibitory potencies. The present results are suggestive that YS-49 and YS-51 exert their inhibitory effects on AA-induced platelet aggregation partly by inhibiting the production of TXA(2) from AA and partly by directly blocking the TP receptor, in addition to the previously reported effects on alpha(2)-adrenergic receptor. On the other hand, higenamine is supposed to antagonize AA-induced platelet aggregation by mostly directly blocking the TP receptor.

Antithrombotic effects of YS-49 and YS-51--1-naphthylmethyl analogs of higenamine

The antiplatelet and antithrombotic effects of YS-49 and YS-51--l-naphthylmethyl analogs of higenamine, which is a benzyl-tetrahydroisoquinoline alkaloid isolated from Aconitum japonicum (Ranunculaceae)--were investigated. YS-49 and YS-51 showed inhibitory activities to both human and rat platelet aggregation induced by ADP, collagen and epinephrine. They were more inhibitory to epinephrine-induced aggregation (IC(50); 3.4 and 1.7 microM of YS-49, and 6.0 and 6.3 microM of YS-51 to human and rat platelets, respectively) than ADP- or collagen-induced aggregation. The antithrombotic effects of YS-49 and YS-51 were also observed in both mouse acute thrombosis model and rat arterio-venous shunt (AV shunt) model. The oral administration of YS-49 and YS-51 (50 or 100 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thrombus formed inside the AV shunt tube in rats.