A new diterpenoid alkaloid from Aconitum hemsleyanum

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.

Chemical components of Aconitum barbatum var. puberulum and their cytotoxic and antibacterial activities

Nineteen compounds, including seventeen alkaloids O-methylarmepavine (1), (S)-6-methoxy-1-(4-methoxybenzyl)-2-methyl -1,2,3,4-tetrahydroisoquinolin-7-ol (2), (+)-(IR,laR)-lahydroxymagnocurarin (3), (6R,6aS,P)-(+)-corydine (4), (+)-N-methyllaurotetanine (5), magnoflorine (6), 3-hydroxy-1,2-dimethoxy-5-methyl-5H-dibenzoindol-4-one (7), imperialine (8), crispine B (9), (S)-1-(3-methoxyphenyl)-N-methylpropan-2-amine (10), methyl 2- (acetamino)benzoate (11), 2-carboxyoxanilic acid methylester (12), 4-[2-(methoxycarbonyl) anilino]-4-oxobutanoic acid methyl ester (13), N-methylcorydaldine (14), N-methyl-6,7- dimethoxyisoquinolone (15), (5S,6R,7S,8R)-5-amino-(2Z,4Z)-1,2,3-trihybuta-2,4-dienyloxypentane- 6,7,8,9-tetraol (16), nicotinic acid (17), and two megastigmane type compounds, S(+)- dehydrovomifoliol (18) and megastigmane (19), were isolated from the Aconitum barbatum var. puberulum Ledeb. Compounds 1-3 and 5-19 were isolated from this plant for the first time, of which compound 11 was isolated from natural source for the first time. Cytotoxicity evaluation revealed that compound 5 displayed mild cytotoxicity against the Hela cell lines (IC50 13.69 ± 0.036 μM). Antibacterial activity evaluation revealed that compounds 1 and 6 showed strong antibacterial activity against the Gram-positive bacterium, S. aureus.

Aconitum coreanum Rapaics: Botany, traditional uses, phytochemistry, pharmacology, and toxicology

The present review summarizes the multifaceted uses and recent findings regarding the phytochemistry, traditional use, pharmacology, and toxicity of the extracts and compounds of Aconitum coreanum Rapaics (Ranunculaceae) for the first time to facilitate further research and exploitation of these types of compounds and the utilization of A. coreanum plants. A. coreanum is one of the most important medicinal Aconitum species and has been traditionally and popularly used in China and other Asian countries for the treatment of headaches and migraines, Bi syndrome induced by wind, cold and dampness, and facial paralysis. Phytochemical studies have led to the isolation of 55 distinct small molecule compounds from A. coreanum, most of which are diterpenoid alkaloids. Related pharmacological studies have focused primarily on the antiarrhythmic, anti-inflammatory, analgesic, and anticancer activities of A. coreanum and its derived drugs. Alkaloids have been demonstrated to be the main active ingredients in this plant. In particular, hetisine-type DAs, mainly Guan-fu base A and its analogues, which possess prominent antiarrhythmic effects, other effects, and hypotoxicity, could be regarded as the representative constituents of A. coreanum. Polysaccharides from A. coreanum also displayed broad bioactivities, demonstrating great potential for further research and exploitation. However, few of the current studies have examined the main active components in A. coreanum from different regions. In addition, most of the pharmacological studies on A. coreanum polysaccharides were carried out using crude or poorly characterized fractions. Finally, reliable analytical methods and deeper studies on the toxicity of the compounds from A. coreanum are needed to ensure the safe usage of these products.

Isoquinoline Alkaloid Contents in Macleaya cordata Extracts and Their Acetylcholinesterase and Butyrylcholinesterase Inhibition

An important strategy for treating neurodegenerative disorders is to maintain the levels of acetylcholine in the synaptic cleft by blocking the cholinesterases. Searching for new effective compounds with inhibited acetylcholinesterase and butyrylcholinesterase activity is one of the most significant challenges of the modern scientific research. The aim of this study was the optimization of the condition for cholinesterase activity determination by high-performance liquid chromatography coupled with diode array detector (HPLC-DAD) in terms of concentrations of enzymatic reaction mixture components, temperature of incubation, and incubation time. In vitro investigation of acetylcholinesterase and butyrylcholinesterase activity inhibition by some isoquinoline alkaloids and extracts obtained from the aerial part and roots of Macleaya cordata collected in May, July, and September. Acetylcholinesterase and butyrylcholinesterase activity inhibition of the extracts obtained from the plant had not been tested previously. The application of the HPLC method allowed eliminating absorption of interfering components, for example, alkaloids such as sanguinarine and berberine. The HPLC method was successfully applied for the evaluation of the acetylcholinesterase inhibitory activity in samples such as plant extracts, especially those containing colored components adsorbing at the same wavelength as the adsorption wavelength of 5-thio-2-nitro-benzoic acid, which is the product of the reaction between thiocholine (product of the hydrolysis of acetyl/butyrylthiocholine reaction) with Ellman’s reagent. Moreover, liquid chromatography coupled with a triple quadrupole mass spectrometer (LC–QqQ–ESI–MS/MS) analysis allowed evaluating the identification of relevant bioactive compounds in the obtained plant extracts. The investigated alkaloids, especially sanguinarine and chelerythrine, and all the Macleaya cordata extracts, especially the extract obtained from the aerial part collected in May, exhibited very high cholinesterase activity inhibition. HPLC-DAD was also applied for the kinetics study of the most active alkaloids sanguinarine and chelerythrine. Our investigations demonstrated that these plant extracts can be recommended for further in vivo experiments to confirm their cholinesterase inhibition activity.

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

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

Processing methods and mechanisms for alkaloid-rich Chinese herbal medicines: A review

The processing of Chinese herbal medicine is a form of pharmaceutical technology developed over thousands of years, in order to increase efficiency and decrease toxicity of herbs in traditional Chinese medicine (TCM). Herbal processing is essential for safe and effective application of TCM in clinical practice, as it alters the active chemical components and therefore the functions of herbal medicines. Alkaloid-rich herbal medicines in TCM are commonly processed by cleansing, cutting, processing by dry stir-frying, stir-frying with liquid adjuvants, and processing by water decoction. In addition, commonly used adjuvants for processing alkaloid-rich herbal medicines are river sand, wine, vinegar, brine, honey and herbal juice. For alkaloid-rich herbal medicines, the main chemical reactions that occur during processing include hydrolysis, oxidation, replacement, decomposition and condensation. This paper aimed to summarize the processing methods and mechanisms for alkaloid-rich Chinese herbal medicines, and provide much-needed theoretical support and scientific evidence for understanding those mechanisms and effects. Information on processing methods for alkaloid-rich herbal medicines was collected from classic books of herbal medicine, PhD and MSc dissertations, online scientific databases including PubMed, SciFinder, Scopus, Web of Science, Baidu Scholar and Google Scholar. This paper should help to advance our knowledge of the processing mechanisms and aid in the development of processing methods for alkaloid-rich Chinese herbal medicines.