Evaluation of aconitine cardiotoxicity with a heart-on-a-particle prepared by a microfluidic device

A heart-on-a-particle model based on multicompartmental microgel is proposed to simulate the heart microenvironment and study the cardiotoxicity of drugs. The relevant microgel was fabricated by a biocompatible microfluidic-based approach, where heart function-related HL-1 and HUVEC cells were arranged in separate compartments. Finally, the mechanism of aconitine-induced heart toxicity was elucidated using mass spectrometry and molecular biotechnology.

Synthesis and biological evaluation of lycoctonine derivatives with cardiotonic and calcium channels inhibitory activities

In our previous study, a screening of a variety of lycotonine-type diterpenoid alkaloids were screened for cardiotonic activity revealed that lycoctonine had moderate cardiac effect. In this study, a series of structurally diverse of lycoctonine were synthesized by modifying on B-ring, D-ring, E-ring, F-ring, N-atom or salt formation on lycoctonine skeleton. We evaluated the cardiotonic activity of the derivatives by isolated frog heart, aiming to identify some compounds with significantly enhanced cardiac effects, among which compound 27 with a N-isobutyl group emerged as the most promising cardiotonic candidate. Furthermore, the cardiotonic mechanism of compound 27 was preliminarily investigated. The result suggested that the cardiotonic effect of compound 27 is related to calcium channels. Patch clamp technique confirmed that the compound 27 had inhibitory effects on CaV1.2 and CaV3.2, with inhibition rates of 78.52 % ± 2.26 % and 79.05 % ± 1.59 % at the concentration of 50 μM, respectively. Subsequently, the protective effect of 27 on H9c2 cells injury induced by cobalt chloride was tested. In addition, compound 27 can alleviate CoCl2-induced myocardial injury by alleviating calcium overload. These findings suggest that compound 27 was a new structural derived from lycoctonine, which may serve as a new lead compound for the treatment of heart failure.

Antinociceptive diterpenoid alkaloids from the roots of Aconitum austroyunnanense

A phytochemical investigation on the roots of Aconitum austroyunnanense afforded three undescribed aconitine-type C₁₉-diterpenoid alkaloids, austroyunnanines A-C (1-3). Structural elucidation of all the compounds were performed by spectral methods such as 1 D and 2 D (¹H-¹H COSY, HMQC, and HMBC) NMR spectroscopy. The isolated alkaloids were tested in vivo for their antinociceptive properties. Consequently, austroyunnanine B (2) exhibited significant antinociceptive effect and its ID₅₀ value (48.0 μmol/kg) was 2-fold less than those of the positive control drugs aspirin and acetaminophen.

Identification and quantification of eight alkaloids in Aconitum heterophyllum using UHPLC-DAD-QTOF-IMS: A valuable tool for quality control

INTRODUCTION

Aconitum spp. are prime medicinal plants rich in alkaloids and have been used as the main constituents of traditional medicine in India and China. The whole plant can be toxic and creates pathophysiological conditions inside the human body. Therefore, simultaneous quantification of alkaloids within plant parts and herbal medicines associated with this genus is essential for quality control.

OBJECTIVE

We aimed to develop and validate methods using ultra-high-performance liquid chromatography-diode array detector-quadrupole time-of-flight ion mobility mass spectrometry (UHPLC-DAD-QTOF-IMS) and to develop an analytical strategy for the identification and quantification of alkaloid compounds (aconitine, hypaconitine, mesaconitine, aconine, benzoylmesaconitine, benzoylaconine, bulleyaconitine A, and deoxyaconitine) from Aconitum heterophyllum.

METHODOLOGY

We developed a simultaneous identification and quantification method for eight alkaloids using UHPLC-DAD-QTOF-IMS. The method was validated as per International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines and also in IMS mode.

RESULTS

The developed method has good linearity (r²  = 0.997-0.999), LOD (0.63-8.31 μg/mL), LOQ (0.63-2.80 μg/mL), recovery (86.01-104.33%), reproducibility, intra- and inter-day variability (<3.25%), and stability. Significant qualitative and quantitative variations were found among different plant parts (flower, leaf, stem, root, and tuber) and five market products of A. heterophyllum. Furthermore, a total of 21 metabolites were also profiled based on the fragmentation pattern of MS² using the validated method.

CONCLUSION

An appropriate mobile phase using acetonitrile and water in a gradient elution gave a satisfactory chromatographic separation of eight Aconitum alkaloids with their adjacent peaks. Therefore, this method could provide a scientific and technical platform for quality control assurance.

Hybrides of Alkaloid Lappaconitine with Pyrimidine Motif on the Anthranilic Acid Moiety: Design, Synthesis, and Investigation of Antinociceptive Potency

Convenient and efficient routes to construct hybrid molecules containing diterpene alkaloid lappaconitine and pyrimidine fragments are reported. One route takes place via first converting of lappaconitine to 1-ethynyl-lappaconitine, followed by the Sonogashira cross-coupling-cyclocondensation sequences. The other involves the palladium-catalyzed carbonylative Sonogashira reaction of 5'-iodolappaconitine with aryl acetylene and Mo (CO)6 as the CO source in acetonitrile and subsequent cyclocondensation reaction of the generated alkynone with amidines. The reaction proceeded cleanly in the presence of the PdCl2-(1-Ad)2PBn∙HBr catalytic system. The protocol provides mild reaction conditions, high yields, and high atom and step-economy. Pharmacological screening of lappaconitine-pyrimidine hybrids for antinociceptive activity in vivo revealed that these compounds possessed high activity in experimental pain models, which was dependent on the nature of the substituent in the 2 and 6 positions of the pyrimidine nucleus. Docking studies were undertaken to gain insight into the possible binding mode of these compounds with the voltage-gated sodium channel 1.7. The moderate toxicity of the leading compound 12 (50% lethal dose (LD50) value was more than 600 mg/kg in vivo) and cytotoxicity to cancer cell lines in vitro encouraged the further design of therapeutically relevant analogues based on this novel type of lappaconitine-pyrimidine hybrids.

Supramolecular structure, in vivo biological activities and molecular-docking-based potential cardiotoxic exploration of aconine hydrochloride monohydrate as a novel salt form

Despite the high profile of aconine in WuTou injection, there has been no preparative technology or structural studies of its salt as the pharmaceutical product. The lack of any halide salt forms is surprising as aconine contains a tertiary nitrogen atom. In this work, aconine was prepared from the degradation of aconitine in Aconiti kusnezoffii radix (CaoWu). A green chemistry technique was applied to enrich the lipophilic-poor aconine. Reaction of aconine with hydrochloride acid resulted in protonation of the nitrogen atom and gave a novel salt form (C₂₅H₄₂NO₉⁺·Cl^-·H₂O; aconine hydrochloride monohydrate, AHM), whose cation in the crystal structure was elucidated based on extensive spectroscopic and X-ray crystallographic analyses. The AHM crystal had a Z' = 3 structure with three independent cation-anion pairs, with profound conformational differences among the aconine cations. The central framework of each aconine cation was compared with that of previously reported aconitine, proving that protonation of the nitrogen atom induced the structure rearrangement. In the crystal of AHM, aconine cations, chloride anions and water molecules interacted through inter-species O-H...Cl and O-H...O hydrogen bonds; this complex hydrogen-bonding network stabilizes the supramolecular structure. The seriously disordered solvent molecules were treated using the PLATON SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] and their atoms were therefore omitted from the refinement. Bioactivity studies indicated that AHM promoted in vitro proliferative activities of RAW264.7 cells. Molecular docking suggested AHM could target cardiotoxic protein through the hydrogen-bonding interactions. The structural confirmation of AHM offers a rational approach for improving the pharmaceutical technology of WuTou injection.

A Comprehensive In Silico Method to Study the QSTR of the Aconitine Alkaloids for Designing Novel Drugs

A combined in silico method was developed to predict potential protein targets that are involved in cardiotoxicity induced by aconitine alkaloids and to study the quantitative structure⁻toxicity relationship (QSTR) of these compounds. For the prediction research, a Protein-Protein Interaction (PPI) network was built from the extraction of useful information about protein interactions connected with aconitine cardiotoxicity, based on nearly a decade of literature and the STRING database. The software Cytoscape and the PharmMapper server were utilized to screen for essential proteins in the constructed network. The Calcium-Calmodulin-Dependent Protein Kinase II alpha (CAMK2A) and gamma (CAMK2G) were identified as potential targets. To obtain a deeper insight on the relationship between the toxicity and the structure of aconitine alkaloids, the present study utilized QSAR models built in Sybyl software that possess internal robustness and external high predictions. The molecular dynamics simulation carried out here have demonstrated that aconitine alkaloids possess binding stability for the receptor CAMK2G. In conclusion, this comprehensive method will serve as a tool for following a structural modification of the aconitine alkaloids and lead to a better insight into the cardiotoxicity induced by the compounds that have similar structures to its derivatives.

Probing the transcriptome of Aconitum carmichaelii reveals the candidate genes associated with the biosynthesis of the toxic aconitine-type C19-diterpenoid alkaloids

Aconitum carmichaelii has long been used as a traditional Chinese medicine, and its processed lateral roots are known commonly as fuzi. Aconitine-type C₁₉-diterpenoid alkaloids accumulating in the lateral roots are some of the main toxicants of this species, yet their biosynthesis remains largely unresolved. As a first step towards understanding the biosynthesis of aconitine-type C₁₉-diterpenoid alkaloids, we performed de novo transcriptome assembly and analysis of rootstocks and leaf tissues of Aconitum carmichaelii by next-generation sequencing. A total of 525 unigene candidates were identified as involved in the formation of C₁₉-diterpenoid alkaloids, including those encoding enzymes in the early steps of diterpenoid alkaloids scaffold biosynthetic pathway, such as ent-copalyl diphosphate synthases, ent-kaurene synthases, kaurene oxidases, cyclases, and key aminotransferases. Furthermore, candidates responsible for decorating of diterpenoid alkaloid skeletons were discovered from transcriptome sequencing of fuzi, such as monooxygenases, methyltransferase, and BAHD acyltransferases. In addition, 645 differentially expressed genes encoding transcription factors potentially related to diterpenoid alkaloids accumulation underground were documented. Subsequent modular domain structure phylogenetics and differential expression analysis led to the identification of BAHD acyltransferases possibly involved in the formation of acetyl and benzoyl esters of diterpenoid alkaloids, associated with the acute toxicity of fuzi. The transcriptome data provide the foundation for future research into the molecular basis for aconitine-type C₁₉-diterpenoid alkaloids biosynthesis in A. carmichaelii.

Hydroxylation Metabolisms of Crassicauline A in Rats Under Toxic Dose

BACKGROUND AND OBJECTIVES

Crassicauline A, a C₁₉ diterpenoid alkaloid in Aconitum herbs, is an analgesic drug clinically used in China. The in vivo metabolism of crassicauline A is poorly understood, while potential bioactivation is anticipated via hydroxylation metabolism. This work, therefore, aimed to investigate the in vivo hydroxylation metabolism of crassicauline A in rats.

METHODS

Using a de novo developed and validated UPLC-MS/MS method, excretion studies in rats were carried out to investigate the recoveries of crassicauline A and its hydroxylated metabolites in urine and feces. Mass fragmentation analysis was used to identify the detected hydroxylated metabolites. In vitro metabolism assay in liver S9 fraction was employed to preliminarily investigate the inter-species difference of hydroxylation metabolism between rats and human.

RESULTS

At a toxic dose of 100 µg/kg, less than 10% and 5% of the administrated dose of crassicauline A were recovered in the urine and feces after single intravenous and oral administration, respectively. Trace of yunaconitine, a possible 3-hydroxylated metabolite of crassicauline A, was detected in urine samples, but not considered to be derived from the in vivo metabolism, because the recovered yunaconitine and crassicauline A was equivalent to their occurrences in the test article. Another hydroxylated metabolite was detected with much higher levels than yunaconitine. Based on chromatographic behaviors and fragmentation analysis, the hydroxylation site of this metabolite was tentatively identified at C-15 on the skeleton, which might have produced a toxic alkaloid known as deoxyjesaconitine. The in vivo observations were consistent with the preliminary in vitro results in liver S9 fraction, in which an inter-species difference was highlighted that rats demonstrated more hydroxylation than human did.

CONCLUSIONS

This work disclosed that crassicauline A is elimilated in rats predominantly by metabolism under toxic dosage and the hydroxylation probably at C-15 might be a potential bioactivation pathway in both rats and human.

C19-Norditerpenoid Alkaloids from Aconitum szechenyianum

Three new C₁₉-norditerpenoid alkaloids (1–3), along with two known C₁₉-norditerpenoid alkaloids (4,5), have been isolated from Aconitum szechenyianum. Based on extensive spectroscopic techniques (1D, 2D-NMR, IR, and MS) and chemical methods, their structures were established as szechenyianine D (1), szechenyianine E (2), szechenyianine F (3), 8-O-methyl-14-benzoylaconine (4), and spicatine A (5). The immunosuppressive effects of compounds 1–5 were studied using a ConA-induced or LPS-induced splenocyte proliferation model. In vitro tests showed that Compounds 2, 4, and 5 suppressed ConA-induced or LPS-induced splenocyte proliferation in a concentration-dependent manner. The CC₅₀/IC₅₀ values of 2, 4, and 5 suggested that these compounds were potential immunosuppressive agents for the treatment of autoimmune diseases characterized by arthritis, such as rheumatoid arthritis.

Selective dual cholinesterase inhibitors from Aconitum laeve

New lycoctonine-type dual cholinesterase inhibitor, swatinine-C (1), along with three known norditerpenoid alkaloids, hohenackerine (2), aconorine (5) and lappaconitine (6) and two synthetically known but phytochemically new benzene derivatives, methyl 2-acetamidobenzoate (3) and methyl 4-[2-(methoxycarbonyl)anilino]-4-oxobutanoate (4), was isolated from the roots of A. laeve. Structures of new and known compounds (1-6) were established on the basis of latest spectroscopic techniques and by close comparison with the data available in literature. In vitro, compounds (1-6) were tested against AChE and BChE inhibitory activities. Compounds 1 and 2 showed competitive inhibition against AChE (IC₅₀= 3.7 μM, 4.53 μM) and BChE (IC₅₀= 12.23 μM, 9.94 μM), respectively. Compounds 5 and 6 showed promising noncompetitive type of inhibitory profile against AChE (IC₅₀= 2.51 and 6.13 μM) only. Compounds 3 and 4 showed weak inhibitory profile against both AChE and BChE.

Isolation, crystal structure determination and cholinesterase inhibitory potential of isotalatizidine hydrate from Delphinium denudatum

CONTEXT

Delphinium denudatum Wall (Ranunculaceae) is a rich source of diterpenoid alkaloids and is widely used for the treatment of various neurological disorders such as epilepsy, sciatica and Alzheimer's disease.

OBJECTIVE

The present study describes crystal structure determination and cholinesterase inhibitory potential of isotalatazidine hydrate isolated from the aerial part of Delphinium denudatum.

MATERIALS AND METHODS

Phytochemical investigation of Delphinium denudatum resulted in the isolation of isotalatazidine hydrate in crystalline form. The molecular structure of the isolated compound was established by X-ray diffraction. The structural data (bond length and angles) of the compound were calculated by Density Functional Theory (DFT) using B3LYP/6-31 + G (p) basis set. The cholinesterase inhibitory potential of the isolated natural product was determined at various concentrations (62.5, 125, 250, 500 and 1000 μg/mL) followed by molecular docking to investigate the possible inhibitory mechanism of isotalatazidine hydrate.

RESULTS

The compound crystallized in hexagonal unit cell with space group P65. Some other electronic properties such as energies associated with HOMO-LUMO, band gaps, global hardness, global electrophilicity, electron affinity and ionization potential were also calculated by means of B3LYP/6-31 + G (p) basis set. The compound showed competitive type inhibition of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC50 values of 12.13 μM and 21.41 μM, respectively.

DISCUSSION AND CONCLUSION

These results suggest that isotalatazidine hydrate is a potent dual cholinesterase inhibitor and can be used as a target drug in Alzheimer diseases. This is first report indicating isotalatazidine hydrate with anticholinesterase potential.

Two new C19-diterpenoid alkaloids from Aconitum tsaii

Two new C₁₉-diterpenoid alkaloids, 14-benzoylliljestrandisine (1) and 14-anisoylliljestrandisine (2), were isolated from the roots of Aconitum tsaii. Their structures were elucidated by different spectroscopic (IR, UV, 1D and 2D NMR) and mass-spectrometric techniques.

Ignavine: a novel allosteric modulator of the μ opioid receptor

Processed Aconiti tuber (PAT) is used to treat pain associated with various disorders. Although it has been demonstrated that the κ opioid receptor (KOR) signaling pathway is a mediator of the analgesic effect of PAT, active components affecting opioid signaling have not yet been identified. In this study, we explored candidate components of PAT by pharmacokinetic analysis and identified ignavine, which is a different structure from aconitine alkaloids. A receptor binding assay of opioid receptors showed that ignavine specifically binds the μ opioid receptor (MOR), not the KOR. Receptor internalization assay in MOR-expressing cell lines revealed that ignavine augmented the responses produced by D-Ala(2)-N-Me-Phe(4)-Gly-ol(5)-enkephalin (DAMGO), a representative MOR agonist, at a low concentration and inhibited it at a higher concentration. Ignavine also exerted positive modulatory activity for DAMGO, endomorphin-1 and morphine in cAMP assay. Additionally, ignavine alone showed an analgesic effect in vivo. In silico simulation analysis suggested that ignavine would induce a unique structural change distinguished from those induced by a representative MOR agonist and antagonist. These data collectively suggest the possibility that ignavine could be a novel allosteric modulator of the MOR. The present results may open the way for the development of a novel pain management strategy.

Processed aconite root and its active ingredient neoline may alleviate oxaliplatin-induced peripheral neuropathic pain

ETHNOPHARMACOLOGICAL RELEVANCE

Processed aconite root (PA, the root of Aconitum carmichaeli, Ranunculaceae) is a crude drug used in traditional Chinese or Japanese kampo medicine to generate heat in the body and to treat pain associated with coldness. Oxaliplatin (L-OHP) is a platinum-based anticancer drug that frequently causes acute and chronic peripheral neuropathies, including cold and mechanical hyperalgesia.

AIM OF THE STUDY

We investigated the effects of PA on L-OHP-induced peripheral neuropathies and identified the active ingredient within PA extract.

MATERIALS AND METHODS

L-OHP was intraperitoneally injected into mice, and PA boiled water extract was orally administered. Cold and mechanical hyperalgesia were evaluated using the acetone test and the von Frey filament method, respectively. Dorsal root ganglion (DRG) neurons were isolated from normal mice and cultured with L-OHP with or without PA extract. Cell viability and neurite elongation were evaluated.

RESULTS

PA extract significantly attenuated cold and mechanical hyperalgesia induced by L-OHP in mice. In cultured DRG neurons, L-OHP reduced cell viability and neurite elongation in a dose-dependent manner. Treatment with PA extract significantly alleviated the L-OHP-induced reduction of neurite elongation, while the cytotoxicity of L-OHP was not affected. Using activity-guided fractionation, we isolated neoline from PA extract as the active ingredient. Neoline significantly alleviated L-OHP-induced reduction of neurite elongation in cultured DRG neurons in a concentration-dependent manner. Moreover, subcutaneous injection of neoline attenuated cold and mechanical hyperalgesia in L-OHP-treated mice. PA extract and neoline did not show sedation and motor impairment.

CONCLUSIONS

The present study indicates that PA and its active ingredient neoline are promising agents to alleviate L-OHP-induced neuropathic pain.

Alkaloids with antioxidant activities from Aconitum handelianum

A new C20-diterpenoid alkaloid handelidine (1) and twenty-seven known alkaloids (2-28) were isolated from the roots of Aconitum handelianum. Their structures were established on the basis of extensive spectroscopic analyses. The study indicated that denudatine-type C20-diterpenoid alkaloids with vicinal-triol system and benzyltetrahydroisoquinoline alkaloids exhibited significant antioxidant activities measured by three antioxidant test systems. The aconitine-type C19-diterpenoid alkaloids could serve as potential secondary antioxidants for their strong binding effects to metal ions.

Identification of Oxygenated Fatty Acid as a Side Chain of Lipo-Alkaloids in Aconitum carmichaelii by UHPLC-Q-TOF-MS and a Database

Lipo-alkaloid is a kind of C19-norditerpenoid alkaloid usually found in Aconitum species. Structurally, they contain an aconitane skeleton and one or two fatty acid moieties of 3–25 carbon chains with 1–6 unsaturated degrees. Analysis of the lipo-alkaloids in roots of Aconitum carmichaelii resulted in the isolation of six known pure lipo-alkaloids (A1–A6) and a lipo-alkaloid mixture (A7). The mixture shared the same aconitane skeleton of 14-benzoylmesaconine, but their side chains were determined to be 9-hydroxy-octadecadienoic acid, 13-hydroxy-octadecadienoic acid and 10-hydroxy-octadecadienoic acid, respectively, by MS/MS analysis after alkaline hydrolysis. To our knowledge, this is the first time of the reporting of the oxygenated fatty acids as the side chains in naturally-occurring lipo-alkaloids. In order to identify more lipo-alkaloids, a compound database was established based on various combinations between the aconitane skeleton and the fatty acid chain, and then, the identification of lipo-alkaloids was conducted using the database, UHPLC-Q-TOF-MS and MS/MS. Finally, 148 lipo-alkaloids were identified from A. carmichaelii after intensive MS/MS analysis, including 93 potential new compounds and 38 compounds with oxygenated fatty acid moieties.

Network-analysis-guided synthesis of weisaconitine D and liljestrandinine

General strategies for the chemical synthesis of organic compounds, especially of architecturally complex natural products, are not easily identified. Here we present a method to establish a strategy for such syntheses, which uses network analysis. This approach has led to the identification of a versatile synthetic intermediate that facilitated syntheses of the diterpenoid alkaloids weisaconitine D and liljestrandinine, and the core of gomandonine. We also developed a web-based graphing program that allows network analysis to be easily performed on molecules with complex frameworks. The diterpenoid alkaloids comprise some of the most architecturally complex and functional-group-dense secondary metabolites isolated. Consequently, they present a substantial challenge for chemical synthesis. The synthesis approach described here is a notable departure from other single-target-focused strategies adopted for the syntheses of related structures. Specifically, it affords not only the targeted natural products, but also intermediates and derivatives in the three families of diterpenoid alkaloids (C-18, C-19 and C-20), and so provides a unified synthetic strategy for these natural products. This work validates the utility of network analysis as a starting point for identifying strategies for the syntheses of architecturally complex secondary metabolites.

Two new C19-diterpenoid alkaloids from Aconitum straminiflorum

Two new C19-diterpenoid alkaloids, straconitines A (1) and B (2), were isolated from the roots of Aconitum straminiflorum. Their structures were elucidated as 14-benzoylducloudine D (1) and 6-hydroxy-14-benzoylducloudine D (2) based on spectroscopic analysis, including IR, ESI-MS, HR-ESI-MS, 1D, and 2D NMR.

Norditerpenoid alkaloids from Delphinium anthriscifolium

Two new norditerpenoid alkaloids with lycoctonine skeleton, anthriscifolcones A (1) and B (2), were isolated from the whole plant of Delphinium anthriscifolium var. Majus by extensive column chromatography. Their structures were established by IR, MS, (1)H NMR, (13)C NMR, and 2D NMR methods (including HSQC, (1)H-(1)H COSY, HMBC, and NOESY experiments).

Pharmacokinetics and bioavailability study of neoline in Beagle dogs

This paper is aim to investigate the pharmacokinetics and absolute bioavailability of neoline in Beagle dogs, and provide a theoretical basis for further study. Ethyl acetate was used for liquid-liquid extracting after 10% ammonia alkalizing. The method of UPLC-Q-TOF-MS was established for the determination of neoline plasma concentrations. Beagle dogs were orally or intravenously administered with neoline for pharmacokinetic and absolute bioavailability study. Good linear relationship of neoline was found over the range of 0.1-4 mg x L(-1) (R2 = 0.9982) and 2-100 microg x L(-1) (R2 = 0.9945). Intra-and inter-day precision, expressed as the relativestandard (RSD) were less than 5.0%. Accuracy, expressed as the relative error (RE) was within 90.0%-115%. The recovery of neoline in dog plasma was more than 80%. After 6 mg x kg(-1) for ig and 1 mg x kg(-1) for iv administration of neoline, the main pharmacokinetic parameters were analyzed with Winnonlin software. t(1/2) were (313.88 +/- 63.18), (236.33 +/- 229.84) min, and AUC(0-infinity) were (58,027.40 +/- 14,132.69), (473,578.02 +/- 82,333.08) min x microg x L(-1) for ig and iv administration respectively. The absolute bioavail ability was (73.15 +/- 10.29) %. The method of UPLC-Q-TOF-MS described in the report was sensitive, reliable and specific, and suitable for pharmacokinetic study of neoline in Beagle dog. The high absolute bioavailability of neoline in dog suggested good absorption of neline which was worth of further investigation.

[Study on change rule of 6 ester-type alkaloids in process of Heishunpian]

To study the variation of six ester-type alkaloids and characteristic fingerprints in the process from Radix Aconite Lateralis to Heishunpian and lay a foundation for the study of the processing principle of Heishunpian, HPLC. analysis was performed on a Phenomenex Gemini C18 (4.6 mm x 250 mm, 5 microm) with acetonitrile and 40 mmol x L(-1) ammonium acetate (adjusted to pH 10 with concentrated ammonia water) as mobile phase. The detection wavelength was set at 235 nm. The flow rate was set at 0.8 mL x min(-1) and the injection volume was 10-20 microL. Six ester-type alkaloids were determined and characteristic fingerprints of the process were established. As the process continues, the contents of diester diterpene alkaloids were decreased step by step, while the contents varia tion of monoester diterpene alkaloids were not obvious. Each sample showed significant difference in characteristic fingerprints. With the exception of 6 known monoester diterpene alkaloids and diester diterpene alkaloids, 13 peaks were marked in the characteristic fingerprints, of which the total change rule of the other 7 unknown peaks were similar with 3 diester diterpene alkaloids. The established method is accurate, reliable and repeatable, and can provide reference for revealing change rule of index components and illuminating processing principle in the process of Heishunpian.

Distribution of toxic alkaloids in tissues from three herbal medicine Aconitum species using laser micro-dissection, UHPLC-QTOF MS and LC-MS/MS techniques

Aconite poisoning continues to be a major type of poisoning caused by herbal drugs in many countries. Nevertheless, despite its toxic characteristics, aconite is used because of its valuable therapeutic benefits. The aim of the present study was to determine the distribution of toxic alkaloids in tissues of aconite roots through chemical profiling. Three species were studied, all being used in traditional Chinese Medicine (TCM) and traditional Indian medicine (Ayurveda), namely: Aconitum carmichaelii, Aconitum kusnezoffii and Aconitum heterophyllum. Laser micro-dissection was used for isolation of target microscopic tissues, such as the metaderm, cortex, xylem, pith, and phloem, with ultra-high performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS) employed for detection of metabolites. Using a multi-targeted approach through auto and targeted LC-MS/MS, 48 known compounds were identified and the presence of aconitine, mesaconitine and hypaconitine that are the biomarkers of this plant was confirmed in the tissues. These results suggest that the three selected toxic alkaloids were exclusively found in A. carmichaelii and A. kusnezoffii. The most toxic components were found in large A. carmichaelii roots with more lateral root projections, and specifically in the metaderm, cork and vascular bundle tissues. The results from metabolite profiling were correlated with morphological features to predict the tissue specific distribution of toxic components and toxicity differences among the selected species. By careful exclusion of tissues having toxic diester diterpenoid alkaloids, the beneficial effects of aconite can still be retained and the frequency of toxicity occurrences can be greatly reduced. Knowledge of tissue-specific metabolite distribution can guide users and herbal drug manufacturers in prudent selection of relatively safer and therapeutically more effective parts of the root. The information provided from this study can contribute towards improved and effective management of therapeutically important, nonetheless, toxic drug such as Aconite.

Ring A conformation of aconine and pseudaconine in CDCl3

On the basis of intensive interpretation of the 1H NMR spectroscopic data, the ring A conformation of aconine (1) was speculated as twist boat in CDCl3, and as chair or twist boat in acetone-d6 and pyridine-d5. The ring A of pseudaconine (2) adopts the chair conformation in CDCl3, acetone-d6, and pyridine-ds. Accordingly, the boat conformation of ring A in these two diterpenoid alkaloids in CDCl3 reported in the literature [1] should be revised. The difference in 13C NMR data for the same compound (1 or 2) in two different solvents (CDCl3, pyridine-d5) can be attributed to solvent effects.

Three new diterpenoid alkaloids from the roots of Aconitum duclouxii

Three new C₁₉-diterpenoid alkaloids, ducloudines C (1), D (2), and E (3), were isolated from the roots of Aconitum duclouxii. Their structures were established on the basis of extensive spectroscopic analyses. Ducloudine C (1) is the first aconitine-type C₁₉-diterpenoid alkaloid with a C=O group at C-3 and a C=C bond between C-1 and C-2. All compounds were tested for their biological activities against one pathogenic fungi and two pathogenic bacteria.

Total synthesis, relay synthesis, and structural confirmation of the C18-norditerpenoid alkaloid neofinaconitine

The first total synthesis of the C18-norditerpenoid aconitine alkaloid neofinaconitine and relay syntheses of neofinaconitine and 9-deoxylappaconitine from condelphine are reported. A modular, convergent synthetic approach involves initial Diels-Alder cycloaddition between two unstable components, cyclopropene 10 and cyclopentadiene 11. A second Diels-Alder reaction features the first use of an azepinone dienophile (8), with high diastereofacial selectivity achieved via rational design of siloxydiene component 36 with a sterically demanding bromine substituent. Subsequent Mannich-type N-acyliminium and radical cyclizations provide complete hexacyclic skeleton 33 of the aconitine alkaloids. Key endgame transformations include the installation of the C8-hydroxyl group via conjugate addition of water to a putative strained bridghead enone intermediate 45 and one-carbon oxidative truncation of the C4 side chain to afford racemic neofinaconitine. Complete structural confirmation was provided by a concise relay synthesis of (+)-neofinaconitine and (+)-9-deoxylappaconitine from condelphine, with X-ray crystallographic analysis of the former clarifying the NMR spectral discrepancy between neofinaconitine and delphicrispuline, which were previously assigned identical structures.

A novel concept for detoxification: complexation between aconitine and liquiritin in a Chinese herbal formula ('Sini Tang')

ETHNOPHARMACOLOGICAL RELEVANCE

Sini Tang (SNT) is a traditional Chinese herbal formulation consisting of three different herbs: Aconitum carmichaelii (Fuzi), Zingiber officinale (Ganjiang), and Glycyrrhiza uralensis (Gancao). For this study, we modified this mixture by adding the bark of Cinnamomum cassia (Rougui, ). Aconitum carmichaelii contains aconitine and its derivatives, all of which are highly toxic alkaloids. These compounds are commonly detoxified with pyrolytic and hydrolytic pretreatments, such as Heishunpian, which requires repeated soaking in salt water, boiling until the roots turn black, and drying in the oven. We now demonstrate that Glycyrrhiza uralensis, which is often used in Traditional Chinese Medicine for detoxification, reduces the concentration of free aconitine in decoctions by forming a complex between liquiritin and aconitine.

MATERIALS AND METHODS

Aqueous extracts of SNT, each individual herb or herbal mixture, and methanolic extracts of individual herbs were tested for free aconitine by HPLC coupled with a diode array detector. A detected complex was investigated by NMR and UV/vis spectroscopy. The continuous variations method and (1)H-NMR titrations provided the complex stoichiometry and binding constant. A 2D-ROESY experiment was performed to obtain the structural details of the formed complex.

RESULTS

A fast and simple HPLC method was developed to determine the amounts of aconitine and its derivatives found in herbal extracts. The Heishunpian pretreatment led to nearly complete pyrolysis and hydrolysis of the toxic compounds. However, in some batches, considerable amounts of aconitine remained. The addition of Glycyrrhiza uralensis to Aconitum carmichaelii, or liquiritin to free aconitine, led to a complexation with aconitine. The complex possessed a 1:1 stoichiometry and a binding constant of ca. 3000 L/mol to 4000 L/mol in mixtures of aqueous methanol.

CONCLUSIONS

A new HPLC based method allows the concentration of toxic aconitine and other diester diterpene alkaloids in herbal extracts to be rapidly determined. This method provides a starting point for the development of routine quality control procedures. The complexation of free aconitine by adding an excess of Glycyrrhiza uralensis or free liquiritin to SNT formulations will make these formulations safer.

Lappaconitine: influence of halogen substituent on the antiarrhythmic activity

The current paper presents research results related to antiarrhythmic activity of halogen-containing derivatives of lappaconitine. Lappaconitine derivatives with iodine, chlorine or bromine substituting the anthranilate moiety at C-5` position were shown in vivo and in vitro to exhibit a more (Br, I) or less (Cl) pronounced antiarrhythmic activity in the models of calcium chloride- and adrenaline-induced arrhythmias as compared with the reference compound lappaconitine. The intensity of antiarrhythmic action depending on halogen substituent was found to be expressed by the following order: Cl < I < Br.

The effects of Rhizoma Zingiberis on pharmacokinetics of six Aconitum alkaloids in herb couple of Radix Aconiti Lateralis-Rhizoma Zingiberis

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Aconiti Lateralis (Fuzi in Chinese, derived from the lateral roots of Aconitum Carmichaeli Debx.) is widely used for the treatment of heart failure, internal cold, arthralgia, diarrhea and edema for thousands of years. It was usually prescribed in combination with Rhizoma Zingiberis (Ganjiang in Chinese, derived from the dry rhizome of Zingiber officinale Rosc.) to decrease toxicity and increase efficacy.

AIM OF THE STUDY

In order to investigate the influence of Rhizoma Zingiberis on pharmacokinetics of six Aconitum alkaloids, i.e. aconitine (AC), hypaconitine (HA), mesaconitine (MA), benzoylaconine (BAC), benzoylhypaconine (BHA) and benzoylmesaconine (BMA), in Fuzi-Ganjiang herb couple, the comparative pharmacokinetics of six Aconitum alkaloids after oral administration of Fuzi and Fuzi-Ganjiang aqueous extract was carried out.

MATERIALS AND METHODS

A sensitive, specific and rapid LC-MS/MS method was developed to determine the six analytes in plasma. Then the rats were randomly divided into two groups and orally administered with Fuzi and Fuzi-Ganjiang aqueous extract. At designated time points after oral administration, the concentrations of the six Aconitum alkaloids in rat plasma were determined, and main pharmacokinetic parameters were investigated using 3P97 (Practical Pharmacokinetics Program Version 1.0).

RESULTS

Comparing with Fuzi group, both T1/2 and AUC0-t of AC and HA decreased (P<0.05), while T1/2, AUC0-t and Cmax of BAC, BHA increased (P<0.05) in Fuzi-Ganjiang group, which indicated that Ganjiang could promote the elimination of AC and HA and enhance the absorption of BAC, BHA and BMA.

CONCLUSION

The differences of pharmacokinetics of Aconitum alkaloids in rat plasma could support those of pharmacologics and toxicity in previous reports between Fuzi and Fuzi-Ganjiang herb couple. The results might be helpful in explaining the mechanism of combination of Fuzi-Ganjiang to decrease toxicity and increase efficacy.

[Chemical constituents of Aconitum bulleyanum]

OBJECTIVE

To study the chemical constituents of chloroform fraction from Aconitum bulleyanum.

METHODS

The compounds were isolated by various chromatographic techniques and identified by spectroscopic methods.

RESULTS

7 compounds were obtained and identified as yunaconitine (1), crassicaudine (2), foresaconitine (3), chasmaconitine (4), bulleyaconitine A (5), franchetine (6), and beta-sitosterol (7), CONCLUSION: Compounds 2-7 are isolated from this plant for the first time.

[Comparison of content of total alkaloids and aconitine in Aconitum szechenyianum from different producing areas on basis of macroporous adsorption resin purification technology]

OBJECTIVE

To optimize the conditions of purifying the total alkaloids in Aconitum szechenyianum with macroporous adsorption resin, and compare the content of total alkaloids and aconitine in A. szechenyianum from different producing areas, in order to provide basis for further studies.

METHOD

The orthogonal experiment method was adopted for optimizing the conditions of purifying the total alkaloids in A. szechenyianum with macroporous adsorption resin. The content of total alkaloids and aconitine were determined by using the titration method. The total alkaloids in A. szechenyianum from different producing areas were purified under optimum processing conditions. Aconitine was determined by HPLC.

RESULT

Different processing conditions showed different influences on the purification of total alkaloids. The optimum conditions were resin type HPD-722, ethanol concentration of 80% , and ethanol elution volume of 80 mL x min(-1). The contents of aconitine in A. szechenyianum from different producing areas--Qinghai, Maxianshan, Ningxia and Yongdeng were 0.493 5, 0.883 5, 1.527 8, 1.664 4 mg x g(-1), respectively.

CONCLUSION

The optimum processing conditions used in this essay could be used for purifying the total alkaloids and aconitine. A. szechenyianum from Yongdeng and Gansu contains the highest content of aconitine.

Conversional synthesis of heteratisine

The first conversional synthesis of heteratisine has been accomplished in 14 steps and 3.2% overall yield from deltaline, mainly including deoxygenation at C-10, removal of the dioxymethylene moiety, O-demethylation, as well as Baeyer-Villiger oxidation.

Identification and determination of Aconitum alkaloids in Aconitum herbs and Xiaohuoluo pill using UPLC-ESI-MS

A rapid, specific, and sensitive ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS) method to examine the chemical differences between Aconitum herbs and processed products has been developed and validated. Combined with chemometrics analysis of principal component analysis (PCA) and orthogonal projection to latent structural discriminate analysis, diester-diterpenoid and monoester-type alkaloids, especially the five alkaloids which contributed to the chemical distinction between Aconitum herbs and processed products, namely mesaconitine (MA), aconitine (AC), hypaconitine (HA), benzoylmesaconitine (BMA), and benzoylhypaconitine (BHA), were picked out. Further, the five alkaloids and benzoylaconitine (BAC) have been simultaneously determined in the Xiaohuoluo pill. Chromatographic separations were achieved on a C₁₈ column and peaks were detected by mass spectrometry in positive ion mode and selected ion recording (SIR) mode. In quantitative analysis, the six alkaloids showed good regression, (r) > 0.9984, within the test ranges. The lower limit quantifications (LLOQs) for MA, AC, HA, BMA, BAC, and BHA were 1.41, 1.20, 1.92, 4.28, 1.99 and 2.02 ng·mL⁻¹, respectively. Recoveries ranged from 99.7% to 101.7%. The validated method was applied successfully in the analysis of the six alkaloids from different samples, in which significant variations were revealed. Results indicated that the developed assay can be used as an appropriate quality control assay for Xiaohuoluo pill and other herbal preparations containing Aconitum roots.

Synthesis of taxane ABC tricyclic skeleton from lycoctonine

A new conversional synthesis of the ABC ring system of taxoids from the C19-diterpenoid alkaloid lycoctonine was developed in 6 steps with 2% overall yield. The distinctive features of the conversion include pinacol rearrangement, enlargement of ring B, and opening of a four-membered ring.

Studies on the relative reactivity of three hydroxyl groups in aconitine

The relative reactivity of three hydroxyl groups in aconitine toward acetylation, chlorination, sulfonylation, and oxidation has been studied in this paper. The reduction of C-3 ketone and C-15 ketone derivatives of aconitine was also investigated. It was found that (1) the relative reactivity of three hydroxyl groups toward acetylation, chlorination, and sulfonylation is 3-OH>13-OH>>15-OH; (2) 3-OH is much more reactive than 15-OH toward oxidation; and (3) reduction of the carbonyl group at C-3 with NaBH(4) generated a pair of C-3 epimers, while the reduction products of the carbonyl group at C-15 depend largely on the specific reducing agent and the absolute configuration of 16-OCH(3). When the substrate has 16β-OCH(3), its carbonyl group at C-15 can be reduced with NaBH(4) to yield exclusively the 15α-OH-containing product. Upon replacement of reducing agent NaBH(4) with LiAlH(4), the C-15 carbonyl group can be reduced to yield a pair of C-15 epimers. On the other hand, when the substrate has 16α-OCH(3), C-15 carbonyl group can only be reduced to generate 15α-OH-containing product.

Biomimetic conversion of aconitine-type C19-diterpenoid alkaloids to lactone-type alkaloids

The first biomimetic conversion from the aconitine-type C(19)-diterpenoid alkaloids to the corresponding alkaloids of lactone-type C(19)-diterpenoid alkaloid has been achieved. Chasmanine was used as starting material with Baeyer-Villiger oxidation as a key reaction. It was also observed that the oxygenated group at C-16 did not change the relative migration tendencies of C-13 and C-9 during the oxidation. Meantime, a novel D-ring fragmented compound was obtained during the course of the present investigation. The plausible mechanism of the formation of this compound was also proposed.

[Determination of content changes of three diester-diterpenoid alkaloids in compatibility of radix aconiti laterlis preparata and Rhizoma pinelliae, Fructus trichosanthis, Bulbus fritillariae, Radix ampelopsis, Rhizoma bletillae by HPLC]

OBJECTIVE

To analyze the three diester-alkaloids content in the decoctions before and after Radix aconiti lateralis preparata combined with Rhizoma pinelliae, Fructus trichosanthis, Bulbus fritillariae, Radix ampelopsis, Rhizoma bletillae, respectively.

METHODS

HPLC analysis was performed on a Agilent Extend C18 column,eluted with a mobile phase consisted of acetonitrile/methanol - 35 mmol/L ammonium acetate and gradient elution,with a flow rate of 0.6 ml/min and the detection wavelength of 235 nm.

RESULTS

The contents of three diester-alkaloids in the co-decoctions of Radix aconiti laterlis preparata combined with Rhizoma pinelliae, Fructus trichosanthis, Bulbus fritillariae, Rhizoma bletillae were more than that of single Radix aconiti laterlis preparata decoction, expect the Bulbus fritillariae cirrhosae,Radix ampelopsis and Rhizoma pinelliae praeparatum. From the result,we can found that the content of three diester-alkaloids in decoctions was correlated with the decoction pH.

CONCLUSION

The pH of decoction is one of the most important factors to relate the three diester-alkaloids content in the decoctions.

X-ray crystallographic study of ranaconitine

The crystal structure of natural diterpenoid alkaloid ranaconitine isolated from Aconitum sinomontanum Nakai has been determined by single crystal X-ray diffraction analysis. The crystal presents a monoclinic system, space group C2 with Z = 4, unit cell dimensions a = 30.972(19) angstrom, b = 7.688(5) angstrom, and c = 19.632(12) angstrom. Moreover, the intermolecular O-H...O hydrogen bonds and weak pi-pi interactions play a critical role in expanding the dimensionality.

[Studies on new hydrolysate of aconitine using HPLC-MS(n) and quantum chemistry calculation]

OBJECTIVE

To study the new hydrolysate of aconitine using HPLC-MS(n) and quantum chemistry calculation.

METHOD

The HPLC method was applied in gradient elution program and the mass spectrometry was in positive ion mode. Geometries of the possible hydrolysates were optimized at DFT/6-31G(d) level.

RESULT

The new hydrolysate was found and its protonated molecularions was at m/z 482. The quantum chemistry calculation results show that the product of elimination reations at C8 and C15 got the lowest energy conformation. The compound at m/z 482 was decluced to be the hydrolysate of carbony at C15.

CONCLUSION

Delydration aconine was detected for the first time and the new hydrolysis pathways of aconitine in water were deduced.

Pharmacokinetic study of lappaconitine hydrobromide in mice by LC-MS

A high sensitive and rapid method was developed for the analysis of lappaconitine in mouse plasma using liquid chromatography coupled to mass spectrometry (LC-MS). Detection was performed by positive ion electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode, monitoring the transitions m/z 585 --> m/z 535 and m/z 356 --> m/z 192, for the quantification of lappaconitine and tetrahydropalmatine (internal standard, IS), respectively. The method was linear over the concentration range of 3.0-2000.0 ng x mL(-1). The lower limit of quantification was 3.0 ng x mL(-1). Intra- and inter-run precisions (RSD) were both less than 9.9% and accuracy (RE) within +/- 4.8%. After single intravenous injections of lappaconitine hydrobromide at 1.0, 2.0 and 4.0 mg x kg(-1), the elimination half-lives (t(1/2)) were 0.47, 0.48 and 0.49 h, and the areas under the curve (AUC(0-t)) were 55.5, 110.5 and 402.9 ng x h x mL(-1), separately. The pharmacokinetic profile of lappaconitine was linear at relatively lower dose levels (1.0-2.0 mg x kg(-1)). When the dose increased farther to 4.0 mg x kg(-1), the Vz and CL decreased, and the increase fold of the AUC was much larger than that of the dose.

Post-intoxication inhibition of botulinum neurotoxin serotype A within neurons by small-molecule, non-peptidic inhibitors

Botulinum neurotoxins (BoNTs) comprise seven distinct serotypes that inhibit the release of neurotransmitter across neuromuscular junctions, resulting in potentially fatal flaccid paralysis. BoNT serotype A (BoNT/A), which targets synaptosomal-associated protein of 25kDa (SNAP-25), is particularly long-lived within neurons and requires a longer time for recovery of neuromuscular function. There are currently no treatments available to counteract BoNT/A after it has entered the neuronal cytosol. In this study, we examined the ability of small molecule non-peptidic inhibitors (SMNPIs) to prevent SNAP-25 cleavage post-intoxication of neurons. The progressive cleavage of SNAP-25 observed over 5 h following 1 h BoNT/A intoxication was prevented by addition of SMNPIs. In contrast, anti-BoNT/A neutralizing antibodies that strongly inhibited SNAP-25 cleavage when added during intoxication were completely ineffective when added post-intoxication. Although Bafilomycin A1, which blocks entry of BoNT/A into the cytosol by preventing endosomal acidification, inhibited SNAP-25 cleavage post-intoxication, the degree of inhibition was significantly reduced versus addition both during and after intoxication. Post-intoxication application of SMNPIs, on the other hand, was nearly as effective as application both during and after intoxication. Taken together, the results indicate that competitive SMNPIs of BoNT/A light chain can be effective within neurons post-intoxication.

Semisynthesis and pharmacological investigation of lipo-alkaloids prepared from aconitine

Processed aconite drugs are widely used in Eastern medicine as painkillers and antirheumatic agents. It is known that the traditional processing of aconite drugs increases the amount of lipo-alkaloids. In order to obtain information about the pharmacological potential of these compounds, semisynthesis of 9 aconitine-derived lipo-alkaloids was carried out and their COX-1, COX-2 and LTB(4) formation inhibitory activities were investigated. It was found that compounds esterified with unsaturated fatty acids demonstrated significant COX-2 inhibitory effects, while in the COX-1 assay only 14-benzoylaconine-8-O-eicosapentaenoate exerted remarkable activity. The inhibition of LTB(4) formation was pronounced in cases of long chain fatty acid derivatives.

Conversional studies towards taxoids from C(19)-diterpenoid alkaloids by the BAC sequence

The conversional synthesis of taxoids by the BAC sequence from the C(19)-diterpenoid alkaloids, 14-acetyltalatisamine (1), yunaconitine (12), and 14-acetylchasmanine (19), was designed and explored. Two aconane-type diterpenes 17 and 28, the advanced intermediates for our conversional synthesis, were synthesized. The key steps include the rupture of the C(7)-C(17) bond, the formation of imine, and the denitrogenation.

Qualitative and quantitative analysis of aconitine-type and lipo-alkaloids of Aconitum carmichaelii roots

By optimizing the extraction and analytical conditions, a reliable and precise HPLC method coupled with photodiode array detection (HPLC-DAD) has been developed for the identification and quantification of three major aconitine-type alkaloids (aconitine, mesaconitine, hypaconitine) in the roots of Aconitum carmichaelii Debeaux. The qualitative analysis of the plant material was carried out by LC-APCI-MS(n). By means of this method, 26 lipo-alkaloids were also identified from the roots of A. carmichaelii. The effect of processing on aconitine-type alkaloids, lipo-alkaloids and pure aconitine was studied. As part of our investigation, two lipo-alkaloids, 14-benzoylaconine-8-palmitate and 14-benzoylaconine-8-linoleate were produced semisynthetically. The COX-1, COX-2 and LTB(4) formation inhibitory activity of aconite root extracts and different types of diterpene alkaloids and the toxicity of lipo-alkaloids were also investigated.

A new norditerpenoid alkaloid from Aconitum taipaicum

To investigate the chemical constituents of the roots of Aconitum taipaicum, silica gel column chromatography was used for the isolation and purification of compounds. A new norditerpenoid alkaloid, isodelelatine (1), along with five known alkaloids, atisine (2), delfissinol (3), liangshanine (4), hypaconitine (5) and delelatine (6) were isolated and identified. The structure of the new compound was elucidated on the basis of spectral data.