A QSAR analysis of toxicity of Aconitum alkaloids

Therapeutic Potentials of Aconite-like Alkaloids: Bioinformatics and Experimental Approaches

Compounds from plants that are used in traditional medicine may have medicinal properties. It is well known that plants belonging to the genus Aconitum are highly poisonous. Utilizing substances derived from Aconitum sp. has been linked to negative effects. In addition to their toxicity, the natural substances derived from Aconitum species may have a range of biological effects on humans, such as analgesic, anti-inflammatory, and anti-cancer characteristics. Multiple in silico, in vitro, and in vivo studies have demonstrated the effectiveness of their therapeutic effects. In this review, the clinical effects of natural compounds extracted from Aconitum sp., focusing on aconitelike alkaloids, are investigated particularly by bioinformatics tools, such as the quantitative structure- activity relationship method, molecular docking, and predicted pharmacokinetic and pharmacodynamic profiles. The experimental and bioinformatics aspects of aconitine's pharmacogenomic profile are discussed. Our review could help shed light on the molecular mechanisms of Aconitum sp. compounds. The effects of several aconite-like alkaloids, such as aconitine, methyllycacintine, or hypaconitine, on specific molecular targets, including voltage-gated sodium channels, CAMK2A and CAMK2G during anesthesia, or BCL2, BCL-XP, and PARP-1 receptors during cancer therapy, are evaluated. According to the reviewed literature, aconite and aconite derivatives have a high affinity for the PARP-1 receptor. The toxicity estimations for aconitine indicate hepatotoxicity and hERG II inhibitor activity; however, this compound is not predicted to be AMES toxic or an hERG I inhibitor. The efficacy of aconitine and its derivatives in treating many illnesses has been proven experimentally. Toxicity occurs as a result of the high ingested dose; however, the usage of this drug in future research is based on the small quantity of an active compound that fulfills a therapeutic role.

Dermal exposure to synthetic musks: Human health risk assessment, mechanism, and control strategy

Synthetic musks (SMs) have been widely used as odor additives in personal care products (PCPs). Dermal exposure to SMs is the main pathway of the accumulation of these chemicals in human kerateins and poses potential health risks. In this study, in silico methods were established to reduce the human health risk of SMs from dermal exposure by investigating the risk mechanisms, designing lower bioaccumulation ability SMs and suggesting proper PCP ingredients using molecular docking, molecular dynamics simulation, and quantitative structure-activity relationship (QSAR) models. The binding energy, a parameter reflecting the binding ability of SMs and human keratin protein (4ZRY), was used as the indicator to assess the human health risk of SMs. According to the mechanism analysis, total energy was found as the most influential molecular structural feature influencing the bioaccumulation ability of a SM, and as one of the main factors influencing the function (i.e., odor sensitivity) of an SM. The 3D-QSAR models were constructed to control the human health risk of SMs by designing lower-risk SMs derivatives. The phantolide (PHAN)- 58 was determined to be the optimum SM derivative with lower bioaccumulation ability (reduced 17.25%) and improved odor sensitivity (increased 7.91%). A further reduction of bioaccumulation ability of PHAN-58 was found when adding proper body wash ingredients (i.e., alkyl ethoxylate sulfate (AES), dimethyloldimethyl (DMDM), EDTA-Na4, ethylene glycol distearate (EGDS), hydroxyethyl cellulose (HEC), lemon yellow and octyl glucose), leading to a significant reduction of the bioaccumulation ability (42.27%) compared with that of PHAN. Results demonstrated that the proposed theoretical mechanism and control strategies could effectively reduce the human health risk of SMs from dermal exposure.

Bulleyaconitine A Inhibits Morphine-Induced Withdrawal Symptoms, Conditioned Place Preference, and Locomotor Sensitization Via Microglial Dynorphin A Expression

Bulleyaconitine A (BAA), a C19-diterpenoid alkaloid, has been prescribed as a nonnarcotic analgesic to treat chronic pain over four decades in China. The present study investigated its inhibition in morphine-induced withdrawal symptoms, conditioned place preference (CPP) and locomotor sensitization, and then explored the underlying mechanisms of actions. Multiple daily injections of morphine but not BAA up to 300 μg/kg/day into mice evoked naloxone-induced withdrawal symptoms (i.e., shakes, jumps, genital licks, fecal excretion and body weight loss), CPP expression, and locomotor sensitization. Single subcutaneous BAA injection (30–300 μg/kg) dose-dependently and completely attenuated morphine-induced withdrawal symptoms, with ED₅₀ values of 74.4 and 105.8 μg/kg in shakes and body weight loss, respectively. Subcutaneous BAA (300 μg/kg) also totally alleviated morphine-induced CPP acquisition and expression and locomotor sensitization. Furthermore, subcutaneous BAA injection also specifically stimulated dynorphin A expression in microglia but not astrocytes or neurons in nucleus accumbens (NAc) and hippocampal, measured for gene and protein expression and double immunofluorescence staining. In addition, subcutaneous BAA-inhibited morphine-induced withdrawal symptoms and CPP expression were totally blocked by the microglial metabolic inhibitor minocycline, dynorphin A antiserum, or specific KOR antagonist GNTI, given intracerebroventricularly. These results, for the first time, illustrate that BAA attenuates morphine-induced withdrawal symptoms, CPP expression, and locomotor sensitization by stimulation of microglial dynorphin A expression in the brain, suggesting that BAA may be a potential candidate for treatment of opioids-induced physical dependence and addiction.

Synthesis and Evaluation of a Series of New Bulleyaconitine A Derivatives as Analgesics

As a nonaddictive analgesic widely used in clinics, the LD₅₀ of bulleyaconitine A is just only 0.92 mg/kg, which exhibits obvious toxicity. Therefore, 31 new non-natural C₁₉-diterpenoid alkaloids (2a-w, 2'a-e, 3, 4a, and 4b) were designed and synthesized from bulleyaconitine A to develop nonaddictive analgesics with low toxicity. The chemical structures were characterized by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry (HRMS) spectra. The analgesic activities were evaluated by a hot plate test in mice. At the dosage of 10 mg/kg, six compounds (2d, 2j, 2k, 2m, 2t, 2w) exhibited good analgesic activities (increased pain threshold >100%) with a long duration. Among them, 2w showed the best analgesic activity and the longest duration. Its pain threshold reached 166.35% in 15 min, peaked at 30 min (182.35%), and remained 82.59% even at 60 min.

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 Metabolomic Study on the Intervention of Traditional Chinese Medicine Qushi Huayu Decoction on Rat Model of Fatty Liver Induced by High-Fat Diet

Qushi Huayu Decoction (QHD), an important clinically proved herbal formula, has been reported to be effective in treating fatty liver induced by high-fat diet in rats. However, the mechanism of action has not been clarified at the metabolic level. In this study, a urinary metabolomic method based on gas chromatography-mass spectrometry (GC-MS) coupled with pattern recognition analysis was performed in three groups (control, model, and QHD group), to explore the effect of QHD on fatty liver and its mechanism of action. There was obvious separation between the model group and control group, and the QHD group showed a tendency of recovering to the control group in metabolic profiles. Twelve candidate biomarkers were identified and used to explore the possible mechanism. Then, a pathway analysis was performed using MetaboAnalyst 3.0 to illustrate the pathways of therapeutic action of QHD. QHD reversed the urinary metabolite abnormalities (tryptophan, uridine, and phenylalanine, etc.). Fatty liver might be prevented by QHD through regulating the dysfunctions of phenylalanine, tyrosine, and tryptophan biosynthesis, phenylalanine metabolism, and tryptophan metabolism. This work demonstrated that metabolomics might be helpful for understanding the mechanism of action of traditional Chinese medicine for future clinical evaluation.

Relationships between the Toxicities of Radix Aconiti Lateralis Preparata (Fuzi) and the Toxicokinetics of Its Main Diester-Diterpenoid Alkaloids

The processed lateral root of Aconitum carmichaelii Deb (Aconiti Radix lateralis praeparata or Fuzi) is a potent traditional herbal medicine extensively used in treatment of cardiovascular diseases, rheumatism arthritis, and bronchitis in many Asian countries. Although Fuzi has promising therapeutic effects, its toxicities are frequently observed. Three main C₁₉-diester-diterpenoid alkaloids (DDAs) are believed to be the principal toxins of the herb. Although toxicokinetic profiles of the toxic DDAs have already been examined in several studies, they have seldom been correlated with the toxicities of Fuzi. The current article aimed to investigate the relationship between the up-to-date toxicokinetic data of the toxic DDAs and the existing evidence of the toxic effects of Fuzi. Relationships between the cardiac toxicity and the plasma and heart concentration of DDAs in mice and rats were established. Based on our findings, clinical monitoring of the plasma concentrations of DDAs of Fuzi is recommended to prevent potential cardiac toxicities. Additionally, caution with respect to potential hepatic and renal toxicity induced by Fuzi should be exercised. In addition, further analyses focusing on the preclinical tissue distribution profile of DDAs and on the long-term toxicokinetic-toxicity correlation of DDAs are warranted for a better understanding of the toxic mechanisms and safer use of Fuzi.

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.

Simultaneous quantification of nine aconitum alkaloids in Aconiti Lateralis Radix Praeparata and related products using UHPLC-QQQ-MS/MS

Aconiti Lateralis Radix Praeparata (Fuzi) is obtained from processed daughter roots of Aconitum carmichaeli, a toxic plant with a high medical value well known in Chinese medicine. In addition to the known toxic alkaloids (aconitine, mesaconitine, and hypaconitine) and bioactive alkaloids (benzoylaconine, benzoylmesaconine, and benzoylhypaconine), three rarely found alkaloids have been previously reported in Fuzi, i.e., yunaconitine, 8-deacetyl-yunaconitine, and crassicauline A, and they were reported in recent years to cause potential risk to patients who took Fuzi or related products. To better control the quality of this herb and its related products and ensure safe use, developing a method to simultaneously determine these 9 alkaloids is important. In this research, sensitive and accurate ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry method was established and used to examine 51 Fuzi and 27 Fuzi-containing products. Unexpectedly, 8-deacetyl-yunaconitine was detected in 17 Fuzi samples (33.3%) and 3 Fuzi-containing products (11.1%); yunaconitine in 10 Fuzi samples (19.6%) and 10 Fuzi-containing products (37.0%); and crassicauline A in 3 Fuzi samples (5.8%). Industry and clinics should be aware of the unusually high detection rate of these three toxic alkaloids in the Fuzi herb and its related products and take the necessary precautions to protect patients from any potential risk.

Ester Hydrolysis Differentially Reduces Aconitine-Induced Anti-hypersensitivity and Acute Neurotoxicity: Involvement of Spinal Microglial Dynorphin Expression and Implications for Aconitum Processing

Aconitines, including bulleyaconitine A, probably the most bioactive and abundant alkaloids in Aconitum plant, are a group of diester C19-diterpenoid alkaloids with one acetylester group attached to C8 of the diterpenoid skeleton and one benzoylester group to C14. Hydrolysis of both groups is involved in the processing of Aconitum, a traditional Chinese medicinal approach. We recently demonstrated that bulleyaconitine A produced anti-hypersensitivity, which was mediated by stimulation of spinal microglial dynorphin A expression. This study aimed to elucidate whether the acetylester and benzoylester groups are involved in aconitine-induced dynorphin A expression, anti-hypersensitivity, neurotoxicity in neuropathic rats. Intrathecal administration of aconitine and benzoylaconine (but not aconine) attenuated mechanical allodynia and heat hyperalgesia, with normalized ED₅₀ values of 35 pmol and 3.6 nmol, respectively. Aconitine and benzoylaconine anti-allodynia was completely blocked by the microglial inhibitor, dynorphin A antiserum, and κ-opioid receptor antagonist. Aconitine and benzoylaconine, but not aconine, stimulated dynorphin A expression in cultured primary spinal microglia, with EC₅₀ values of 32 nM and 3 μM, respectively. Intrathecal aconitine, benzoylaconine and aconine induced flaccid paralysis and death, with normalized TD₅₀ values of 0.5 nmol, 0.2 μmol, and 1.6 μmol, respectively. The TD₅₀/ED₅₀ ratios of aconitine and benzolyaconine were 14:1 and 56:1. Our results suggest that both the C8-acetyl and C14-benzoyl groups are essential for aconitine to stimulate spinal microglial dynorphin A expression and subsequent anti-hypersensitivity, which can be separated from neurotoxicity, because both benzoylaconine and aconine differentially produced anti-hypersensitivity and neurotoxicity due to their different stimulatory ability on dynorphin A expression. Our results support the scientific rationale for Aconitum processing, but caution should be taken to avoid overprocessing and excess hydrolysis of benzolyaconine to aconine.

Total Synthesis of (-)-Cardiopetaline

The total synthesis of (-)-cardiopetaline, an aconitine-type natural product, has been accomplished. Our synthesis involved a Wagner-Meerwein rearrangement of a sulfonyloxirane that enabled, in a single step, the construction of the bicyclo[3.2.1] system in the aconitine skeleton and effective introduction of oxygen functional groups at the appropriate positions.

Neutral fragment filtering for rapid identification of new diester-diterpenoid alkaloids in roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry

A rapid and effective method was developed for separation and identification of diester-diterpenoid alkaloids (DDA) in the roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with high resolution LTQ-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MSⁿ). According to accurate mass measurement and the characteristic neutral loss filtering strategy, a total of 42 diester-diterpenoid alkaloids (DDA) were rapidly detected and characterized or tentatively identified. Meanwhile, the proposed fragmentation pathways and the major diagnostic fragment ions of aconitine, mesaconitine and hypaconitine were investigated to trace DDA derivatives in crude plant extracts. 23 potential new compounds were successfully screened and characterized in Aconitum carmichaeli, including 16 short chain fatty acyls DDA, 4 N-dealkyl DDA and several isomers of aconitine, mesaconitine and hypaconitine.

Quantitative and Qualitative Analysis of Aconitum Alkaloids in Raw and Processed Chuanwu and Caowu by HPLC in Combination with Automated Analytical System and ESI/MS/MS

HPLC in combination with automated analytical system and ESI/MS/MS was used to analyze aconitine (A), mesaconitine (MA), hypaconitine (HA), and their benzoyl analogs in the Chinese herbs Caowu and Chuanwu. First, an HPLC method was developed and validated to determine A, MA, and HA in raw and processed Caowu and Chuanwu. Then an automated analytical system and ESI/MS/MS were applied to analyze these alkaloids and their semihydrolyzed products. The results obtained from automated analytical system are identical to those from ESI/MS/MS, which indicated that the method is a convenient and rapid tool for the qualitative analysis of herbal preparations. Furthermore, HA was little hydrolyzed by heating processes and thus it might account more for the toxicity of processed aconites. Hence, HA could be used as an indicator when one alkaloid is required as a reference to monitor the quality of raw and processed Chuanwu and Caowu. In addition, the raw and processed Chuanwu and Caowu can be distinguished by monitoring the ratio of A and MA to HA.

Terpenoid-Alkaloids: Their Biosynthetic Twist of Fate and Total Synthesis

Terpenes and alkaloids are ever-growing classes of natural products that provide new molecular structures which inspire chemists and possess a broad range of biological activity. Terpenoid-alkaloids originate from the same prenyl units that construct terpene skeletons. However, during biosynthesis, a nitrogen atom (or atoms) is introduced in the form of β-aminoethanol, ethylamine, or methylamine. Nitrogen incorporation can occur either before, during, or after the cyclase phase. The outcome of this unique biosynthesis is the formation of natural products containing unprecedented structures. These complex structural motifs expose current limitations in organic chemistry, thus providing opportunities for invention. This review focuses on total syntheses of terpenoid-alkaloids and unique issues presented by this class of natural products. More specifically, it examines how these syntheses relate to the way terpenoid-alkaloids are made in Nature. Developments in chemistry that have facilitated these syntheses are emphasized, as well as chemical technology needed to conquer those that evade synthesis.

Development and validation of a rapid capillary zone electrophoresis method for the determination of aconite alkaloids in aconite roots

INTRODUCTION

Aconites, with aconite alkaloids as the major therapeutic and toxic components, are used for the treatment of analgesic, antirheumatic and neurological symptoms. Quantification of the aconite alkaloids is important for the quality control of aconite-containing drugs.

OBJECTIVE

To establish a validated capillary zone electrophoresis (CZE) method for the simultaneous determination of six major alkaloids, namely aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine and benzoylhypaconine, in crude and processed aconite roots.

METHODOLOGY

The CZE method was optimised and validated using a stability-indicating method. The optimised running buffer was a mixture of 200 mm Tris, 150 mm perchloric acid and 40% 1,4-dioxane (pH 7.8) with the capillary thermostated at 25 degrees C.

RESULTS

Using the optimised method, six aconite alkaloids were well separated. The established method showed good precision, accuracy and recovery. Contents of these alkaloids in crude and processed aconites were determined and it was observed that the levels of individual alkaloids varied between samples.

CONCLUSION

The developed CZE method was reliable for the quality control of aconites contained in herbal medicines. The method could also be used as an approach for toxicological studies.

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.

Aconitum and Delphinium alkaloids "Drug-likeness" descriptors related to toxic mode of action

Large series of Aconitum and Delphinium alkaloids have been investigated by means of QSAR analysis. Descriptors related to "drug-likeness" of molecules were selected to discriminate between "drugs" and "non-drugs" amongst diterpenoid alkaloids of interest. A usefulness of such approach has been assessed and it proved to give reliable results on whether a particular diterpenoid alkaloid is likely to be either poison or drug. A number of QSAR models with "drug-likeness" descriptors have also been obtained and discussed in terms of their relativity to the mode of toxic action exhibited by the alkaloids. The QSAR models were obtained with r value in the range 0.69-0.94. The q(2) (cross validation of r(2)) values also confirm the statistical significance of our models.

Aconitum and Delphinium sp. alkaloids as antagonist modulators of voltage-gated Na+ channels. AM1/DFT electronic structure investigations and QSAR studies

Early pharmacological studies of Aconitum and Delphinium sp. alkaloids suggested that these neurotoxins act at site 2 of voltage-gated Na(+) channel and allosterically modulate its function. Understanding structural requirements for these compounds to exhibit binding activity at voltage-gated Na(+) channel has been important in various fields. This paper reports quantum-chemical studies and quantitative structure-activity relationships (QSARs) based on a total of 65 natural alkaloids from two plant species, which includes both blockers and openers of sodium ion channel. A series of 18 antagonist alkaloids (9 blockers and 9 openers) have been studied using AM1 and DFT computational methods in order to reveal their structure-activity (structure-toxicity) relationship at electronic level. An examination of frontier orbitals obtained for ground and protonated forms of the compounds revealed that HOMOs and LUMOs were mainly represented by nitrogen atom and benzyl/benzoylester orbitals with -OH and -OCOCH(3) contributions. The results obtained from this research have confirmed the experimental findings suggesting that neurotoxins acting at type 2 receptor site of voltage-dependent sodium channel are activators and blockers with common structural features and differ only in efficacy. The energetic tendency of HOMO-LUMO energy gap can probably distinguish activators and blockers that have been observed. Genetic Algorithm with Multiple Linear Regression Analysis (GA-MLRA) technique was also applied for the generation of three-descriptor QSAR models for the set of 65 blockers. Additionally to the computational studies, the HOMO-LUMO gap descriptor in each obtained QSAR model has confirmed the crucial role of charge transfer in receptor-ligand interactions. A number of other descriptors such as logP, I(BEG), nNH2, nHDon, nCO have been selected as complementary ones to LUMO and their role in activity alteration has also been discussed.

Antiviral and Antimicrobial Evaluation of Some Heterocyclic Compounds from Turkish Plants

Antibiotic resistance has become a problem since the discovery of antibiotics. Not long after the introduction of penicillin, Staphylococcus aureus, which can be also transmitted to humans via milk and milk products, began developing penicillin-resistant strains. Therefore, one approach that has been used for the discovery of new antimicrobial agents from natural sources is based on the evaluation of traditional plant extracts. Natural products have played a pivotal role in antibiotic drug innovation and include aminoglycosides, cephalosporins, macrolides, cycloserine, novobiocin, and lipoproteins. However, only a few antiviral agents are available on the market. To this purpose, we have screened a great number of herbal extracts along with some pure natural substances and obtained interesting findings. This chapter covers the results of our rigorous search for new antiviral and antimicrobial alternative compounds from a number of Turkish plants.