Inhibition of stimulus-triggered and spontaneous epileptiform activity in rat hippocampal slices by the Aconitum alkaloid mesaconitine

Involvement of autophagy in mesaconitine-induced neurotoxicity in HT22 cells revealed through integrated transcriptomic, proteomic, and m6A epitranscriptomic profiling

Background: Mesaconitine (MA), a diester-diterpenoid alkaloid extracted from the medicinal herb Aconitum carmichaelii, is commonly used to treat various diseases. Previous studies have indicated the potent toxicity of aconitum despite its pharmacological activities, with limited understanding of its effects on the nervous system and the underlying mechanisms. Methods: HT22 cells and zebrafish were used to investigate the neurotoxic effects of MA both in vitro and in vivo, employing multi-omics techniques to explore the potential mechanisms of toxicity. Results: Our results demonstrated that treatment with MA induces neurotoxicity in zebrafish and HT22 cells. Subsequent analysis revealed that MA induced oxidative stress, as well as structural and functional damage to mitochondria in HT22 cells, accompanied by an upregulation of mRNA and protein expression related to autophagic and lysosomal pathways. Furthermore, methylated RNA immunoprecipitation sequencing (MeRIP-seq) showed a correlation between the expression of autophagy-related genes and N6-methyladenosine (m6A) modification following MA treatment. In addition, we identified METTL14 as a potential regulator of m6A methylation in HT22 cells after exposure to MA. Conclusion: Our study has contributed to a thorough mechanistic elucidation of the neurotoxic effects caused by MA, and has provided valuable insights for optimizing the rational utilization of traditional Chinese medicine formulations containing aconitum in clinical practice.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.

Neuropharmacological Potential of Diterpenoid Alkaloids

This study provides a narrative review of diterpenoid alkaloids (DAs), a family of extremely important natural products found predominantly in some species of Aconitum and Delphinium (Ranunculaceae). DAs have long been a focus of research attention due to their numerous intricate structures and diverse biological activities, especially in the central nervous system (CNS). These alkaloids originate through the amination reaction of tetra or pentacyclic diterpenoids, which are classified into three categories and 46 types based on the number of carbon atoms in the backbone structure and structural differences. The main chemical characteristics of DAs are their heterocyclic systems containing β-aminoethanol, methylamine, or ethylamine functionality. Although the role of tertiary nitrogen in ring A and the polycyclic complex structure are of great importance in drug-receptor affinity, in silico studies have emphasized the role of certain sidechains in C13, C14, and C8. DAs showed antiepileptic effects in preclinical studies mostly through Na⁺ channels. Aconitine (1) and 3-acetyl aconitine (2) can desensitize Na⁺ channels after persistent activation. Lappaconitine (3), N-deacetyllapaconitine (4), 6-benzoylheteratisine (5), and 1-benzoylnapelline (6) deactivate these channels. Methyllycaconitine (16), mainly found in Delphinium species, possesses an extreme affinity for the binding sites of α7 nicotinic acetylcholine receptors (nAChR) and contributes to a wide range of neurologic functions and the release of neurotransmitters. Several DAs such as bulleyaconitine A (17), (3), and mesaconitine (8) from Aconitum species have a drastic analgesic effect. Among them, compound 17 has been used in China for decades. Their effect is explained by increasing the release of dynorphin A, activating the inhibitory noradrenergic neurons in the β-adrenergic system, and preventing the transmission of pain messages by inactivating the Na⁺ channels that have been stressed. Acetylcholinesterase inhibitory, neuroprotective, antidepressant, and anxiolytic activities are other CNS effects that have been investigated for certain DAs. However, despite various CNS effects, recent advances in developing new drugs from DAs were insignificant due to their neurotoxicity.

Neuropharmacological Effects of Mesaconitine: Evidence from Molecular and Cellular Basis of Neural Circuit

Mesaconitine (MA), a diester-diterpenoid alkaloid in aconite roots, is considered to be one of the most important bioactive ingredients. In this review, we summarized its neuropharmacological effects, including analgesic effects and antiepileptiform effects. Mesaconitine can act on the central noradrenergic system and the serotonin system; behaving like the norepinephrine reuptake inhibitors and tricyclic antidepressants that increase norepinephrine levels in stress-induced depression. Therefore, the possible perspectives for future studies on the depression of MA were also discussed as well. The pharmacological effect of MA on depression is worthy of further study.

A fragmentation study on four C19-diterpenoid alkaloids by electrospray ionization ion-trap time-of-flight tandem mass spectrometry

High-resolution electrospray ionization ion-trap time-of-flight tandem mass spectrometry (HR-ESI-IT-TOF-MS(n)) in positive-ion mode was used to determine the accurate masses and fragmentation pathways of four C(19)-diterpenoid alkaloids, aconitine (1), yunnaconitine (2), crassicauline A (3), and benzoylmesaconine (4). The [M+H](+) ions of compounds 1-4 were readily observed in conventional single-stage mass spectrometry. Based on the MS(1-6) analyses, detailed fragmentation rules of the four compounds were proposed. The neutral losses of AcOH, MeOH, H(2)O, CO, C(2)H(4), PhCOOH and p-OMePhCOOH segments were the characteristic eliminations from the precursor ions due to the presence of acetyl, methoxyl, hydroxyl, N-ethyl, benzoyl and p-methoxyl-benzoyl units in the structures. Benefited from the high resolution of the mass analyzer, the loss of 28 Da corresponding to CO or CH(4) segment in product ions was unambiguously distinguished. The losing sequence of the main substituent groups was summarized as: C(8)-acetyl>C(16)-methotyl>C(15)-hydroxyl>C(6)-methoxyl>C(1)-methoxyl/C(3)-hydroxyl>C(18)-methoxyl>>C(13)-hydroxyl. The sequential loss of (16)-methoxyl moiety and CO (generating from enol-ketone tautomerism) groups could be recognized as the characteristic eliminations for the compounds with C(16)-methoxyl and C(15)-hydroxyl groups simultaneously. The application of HR-ESI-IT-TOF-MS(n) technique to investigate the fragmentation of C(19)-diterpenoid alkaloids provided useful information to understand their fragmentation behaviors.

Quantitative analysis of five toxic alkaloids in Aconitum pendulum using ultra-performance convergence chromatography (UPC2) coupled with mass spectrometry

An UPC²-MS method for simultaneous quantification of the five toxic alkaloids was developed for the quality evaluation of A. pendulum.

A review on phytochemistry, pharmacology and toxicology studies of Aconitum

Objectives

A number of species belonging to herbal genus Aconitum are well-known and popular for their medicinal benefits in Indian, Vietnamese, Korean, Japanese, Tibetan and Chinese systems of medicine. It is a valuable drug as well as an unpredictable toxic material. It is therefore imperative to understand and control the toxic potential of herbs from this genus. In this review, the ethnomedicinal, phytochemistry, pharmacology, structure activity relationship and toxicology studies of Aconitum were presented to add to knowledge for their safe application.

Key findings

A total of about 76 of all aconite species growing in China and surrounding far-east and Asian countries are used for various medical purposes. The main ingredients of aconite species are alkaloids, flavonoids, free fatty acids and polysaccharides. The tuberous roots of genus Aconitum are commonly applied for various diseases such as rheumatic fever, painful joints and some endocrinal disorders. It stimulates the tip of sensory nerve fibres. These tubers of Aconitum are used in the herbal medicines only after processing. There remain high toxicological risks of the improper medicinal applications of Aconitum. The cardio and neurotoxicities of this herb are potentially lethal. Many analytical methods have been reported for quantitatively and qualitatively characterization of Aconitum.

Summary

Aconitum is a plant of great importance both in traditional medicine in general and in TCM in particular. Much attention should be put on Aconitum because of its narrow therapeutic range. However, Aconitum's toxicity can be reduced using different techniques and then benefit from its pharmacological activities. New methods, approaches and techniques should be developed for chemical and toxicological analysis to improve its quality and safety.

Development and assessment of a complete-detoxication strategy for Fuzi (lateral root of Aconitum carmichaeli) and its application in rheumatoid arthritis therapy

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzi (lateral root of Aconitum carmichaeli) is a popular traditional Chinese medicine well known for its both therapeutic and high-toxic activities. Its toxic alkaloid ingredients, mainly aconitine, mesaconitine, and hypaconitine, are responsible for the high toxicity. However, to date, no detoxication strategy is available to completely eliminate Fuzi's toxicity, and, whether Fuzi's efficacy could be kept after detoxication, remain unknown and debatable.

MATERIALS AND METHODS

The purpose of this study was to establish and validate a complete-detoxication strategy for Fuzi via acute toxicity test, to clarify the detoxication mechanism by HPLC and titrimetric analyses, and to evaluate the therapeutic effect of detoxicated Fuzi on adjuvant arthritis (AA). Three processed Fuzi (Bai-fu-pian) with 30-min, 60-min, and 120-min decoctions, respectively, named dBfp-30, dBfp-60, and dBfp-120, were prepared for this study. For the acute toxicity test, their oral doses to male and female Kunming mice were up to 70-190g/kg body weight, and their toxicological profiles were evaluated by median lethal dose (LD50), maximal tolerance dose (MTD), minimal lethal dose (MLD), no-observed-adverse-effect-level (NOAEL), and time-concentration-mortality (TCM) modeling methods using a 14-day schedule with up to five doses. The HPLC analysis was performed to determine the detoxication-induced changes in composition and amount of aconitine, mesaconitine and hypaconitine in Fuzi, whilst the titrimetric method was adopted to estimate the amount changes of Fuzi's total alkaloids. AA model was established by incomplete Freund's adjuvant injection in Wistar rats, and the animal's physiological (body weight, food intake, etc.), clinical (hind paw volume), and immunological (IL-1 and TNF-α) parameters were assessed as markers of inflammation and arthritis.

RESULTS

With increasing decoction time, the acute toxicity of detoxicated Fuzi became decreased in the following order: dBfp-30 (LD50 of 145.1g/kg; MTD of 70g/kg; MLD of 100g/kg; NOAEL of 70g/kg) >dBfp-60 (too large LD50; MTD of 160g/kg; MLD of 190g/kg; NOAEL of 100g/kg) >dBfp-120 (no LD50; unlimited MTD; unlimited MLD; NOAEL of 130g/kg). dBfp-30 and dBfp-60 displayed the toxicity at a dose-dependent manner with maximum mortalities reaching 100% and 50% respectively, whereas no mortality or signs of intoxication was induced by dBfp-120. The chemical analyses revealed a dramatic reduction of the toxic alkaloids as well as total alkaloids in Fuzi after the detoxication, from which no level of aconitine and only minimum residual of mesaconitine (0.56±0.02μg/g) and hypaconitine (8.73±0.13μg/g) were detected in dBfp-120. However, no significant difference of total alkaloid amount was found among dBfp-30, dBfp-60, and dBfp-120 (P>0.05), suggesting an equivalent conversion from toxic alkaloids to its non-toxic derivants in dBfp-120. Further, also no significant differences were seen among dBfp-30, dBfp-60, and dBfp-120 for the therapeutic effects on physiological, clinical, and immunological parameters in AA rat, indicating that dBfp-120 is of non-toxicity and efficacy.

CONCLUSIONS

A complete-detoxication strategy has been developed successfully for ensuring the safe and effective use of Fuzi. The detoxication mechanism associated with elimination of toxic alkaloids has kept Fuzi's efficacy, indicating a non-interdependent relationship between its efficacy and toxicity. This is the first report on such an optimal detoxication strategy and on the application of detoxicated Fuzi in AA. It may provide in depth understanding to the toxicological and pharmacological profiles of Fuzi and further benefit the herbal drug development with safety and efficacy for disease especially RA therapy.

CE-electrochemiluminescence with ionic liquid for the facile separation and determination of diester-diterpenoid aconitum alkaloids in traditional Chinese herbal medicine

A CE-electrochemiluminescence(CE-ECL) detection system, CE/tris(2,2'-bipyridyl) ruthenium(II)ECL with ionic liquid, was established for the determination of diester-diterpenoid aconitum alkaloids (aconitine (AC), mesaconitine (MA) and hypaconitine (HA)) in traditional Chinese herbal medicine. Running buffer containing 25 mM borax-20 mM 1-ethyl-3-methylimidazolium tetrafluoroborate at pH 9.15 was used, which resulted in significant changes in separation and obvious enhancement in ECL intensity for AC, MA and HA with similar structures. End-column detection was achieved in 50 mM phosphate buffer with 5 mM Ru(bpy)₃²⁺ (pH 9.15) at applied detection voltage of 1.20 V when the distance between the Pt working electrode and outlet of capillary (50 cm × 25 μm id) was set at 150 μm. One single quantitative analysis of three alkaloids was achieved at a separation voltage of 15 kV within 10 min. Moreover, two extraction processes (ethanol extraction and ethyl ether extraction after basification) were investigated. The result showed that ethanol extraction process has higher extraction efficiency than ethyl ether extraction process. Under the optimized conditions, the detection limits of AC, MA and HA were 5.62 × 10(-8) , 2.78 × 10(-8) and 3.50 × 10(-9) mol/L (S/N=3), respectively. The method was successfully applied to determine the amounts of AC, MA and HA in the aconitum herbal samples.

Binding of alpha 1-acid glycoprotein with aconitum alkaloids: an investigation using an intensity fading matrix-assisted laser desorption/ionization Fourier transform mass spectrometry method

Intensity fading matrix-assisted laser desorption/ionization (IF-MALDI) mass spectrometry has become an alternative screening approach for the affinity-binding analysis of proteins and peptides with ligands. In this study, an attempt has been made to study the interaction of alpha 1-acid glycoprotein (AGP) with aconitum alkaloids by IF-MALDI Fourier transform ion cyclotron resonance mass spectrometry (IF-MALDI-FT-MS). Compared with the nonbinding internal standard, clear reduction in the ion abundances of the target alkaloids was observed with the addition of AGP. Relative binding affinities of different alkaloids towards the protein could also be estimated using IF-MALDI-FT-MS. The binding affinity was also investigated by using ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization mass spectrometry (ultrafiltration LC-DAD/ESI-MS), and results were consistent with that of IF-MALDI-FT-MS.

14-Benzoyl-mesaconine hydro-chloride methanol monosolvate

The title compound, C₃₁H₄₄N₃O₁₀⁺·Cl⁻·CH₄O, is the methanol solvate of 8-benzo­yloxy-,9,11,11a-tetra­hydroxy-6,10,13-trimeth­oxy-3-meth­oxy­methyl-1-methyl­tetra­deca­hydro-1H-3,6a,12-(epiethane-1,1,2-tri­yl)-7,9-methanona­phtho[2,3-b]azocin-1-ium chloride, the amine-protonated hydro­chloride of 14-benzoyl­mesaconine hydro­chloride. The cation has an aconitine carbon skeleton with four six-membered rings of which three display chair conformations and one a boat conformation, and two five-membered rings with envelope conformations. In the crystal, the components are connected into an infinite chain by inter- and intra­molecular O—H⋯O, N—H⋯O and O—H⋯Cl hydrogen bonds.

Diterpenoid alkaloids

The lasting attention that researchers have devoted to diterpenoid alkaloids is due to their various bioactivities and toxicities, structural complexity, and intriguing chemistry. From 1998 to the end of 2008, more than 300 new diterpenoid alkaloids were isolated from Nature. This review focuses on their structural relationships, and investigations into their chemical reactions, synthesis, and biological activities. A table that lists the names, plant sources, and structural types is given along with 363 references.

Studies on the stability of diester-diterpenoid alkaloids from the genus Aconitum L. by high performance liquid chromatography combined with electrospray ionisation tandem mass spectrometry (HPLC/ESI/MSn)

The stability of diester-diterpenoid alkaloids (DDA) from plants of the genus Aconitum L. has been studied in different solvents and pH buffers. The HPLC/ESIMS method for analysing the concentration of DDA was established and DDA's decomposition products were elucidated by HPLC/ESI-MS/MS(n). In different solvents, e.g. dichloromethane, ether, methanol and distilled water, the decomposition pathways of DDA are quite different and their difference in stabilities depends on the difference of their structures, in which substituents at the N atom and substituents at C-3 are different. The pyrolytic products of DDA, such as deacetoxy aconitine-type alkaloids, have been observed in the above solvents, whereas 8-methoxy-14-benzoyl aconitine-type alkaloids have been obtained only in methanol. Furthermore, the experimental results demonstrate that the stability of DDA depends on pH values of the buffer. Aconine as hydrolysate has been only found in pH 10.0 buffer, and the other hydrolysates and the pyrolyzates of DDA, such as benzoylaconine and deacetoxy aconitine, have been observed in all pH aqueous solutions. The decomposition pathways of DDA in buffers are related to the substituent on the C-3 position. The decomposition pathway of aconitine is similar to that of mesaconitine, but different from that of hypaconitine.

Norditerpenoid alkaloids fromAconitum karakolicumRapaics

Two new norditerpenoid alkaloids, acofamine A (1) and acofamine B (2) were isolated from the aerial parts of Aconitum karakolicum Rapaics. The structures of these compounds were established by spectroscopic methods.

Determination of aconitine in body fluids by LC-MS-MS

A very sensitive and specific method was developed for the determination of aconitine, the main toxic alkaloid from plants of the genus Aconitum L., in biological samples. The method comprised solid-phase extraction using mixed-mode Cs cation exchange columns followed by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Chromatographic separation was achieved with a RP8 column. Detection of aconitine was achieved using electrospray in the positive ionisation mode and quantification was performed using multiple reaction monitoring with m/z 646.4 as precursor ion, i.e. [M+H]+ of aconitine and m/z 586.5, m/z 526.4 and m/z 368.4 as product ions after collision-induced dissociation. The method was fully validated for the analysis of blood samples: the limit of detection and the limit of quantitation were 0.1 ng/g and 0.5 ng/g, respectively. Within the linear calibration range of 0.5-25 ng/g, analytical recovery was 79.9%. In two fatal cases with suspected aconite intoxication, aconitine could be detected in blood samples at concentrations of 10.0 and 12.1 ng/g. In one case, aconitine could also be detected in the stomach content (3 ng/g) and in the other in the urine (180 ng/ml).

Characterization of aconitine-type alkaloids in the flowers of Aconitum kusnezoffii by electrospray ionization tandem mass spectrometry

The fragmentation mechanism of aconitine-type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI-MS(n)) firstly. The analysis of the collision-induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low-energy CID follows a similar pathway. The elimination of a C(8)-substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH(3)COOH, CH(3)OH, H(2)O, BzOH, and CO are the main fragmentation pathways of aconitine-type alkaloids in MS(3) spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo-aconitines has been found for the first time in this plant.