Quinolizidine-Type Alkaloids: Chemodiversity, Occurrence, and Bioactivity

A review on the pharmacology, pharmacokinetics and toxicity of sophocarpine

Sophocarpine is a natural compound that belongs to the quinolizidine alkaloid family, and has a long history of use and widespread distribution in traditional Chinese herbal medicines such as Sophora alopecuroides L., Sophora flavescens Ait., and Sophora subprostrata. This article aims to summarize the pharmacology, pharmacokinetics, and toxicity of sophocarpine, evaluate its potential pharmacological effects in various diseases, and propose the necessity for further research and evaluation to promote its clinical application. A large number of studies have shown that it has anti-inflammatory, analgesic, antiviral, antiparasitic, anticancer, endocrine regulatory, and organ-protective effects as it modulates various signaling pathways, such as the NF-κB, MAPK, PI3K/AKT, and AMPK pathways. The distribution of sophocarpine in the body conforms to a two-compartment model, and sophocarpine can be detected in various tissues with a relatively short half-life. Although the pharmacological effects of sophocarpine have been confirmed, toxicity and safety assessments and reports on molecular mechanisms of its pharmacological actions have been limited. Given its significant pharmacological effects and potential clinical value, further research and evaluation are needed to promote the clinical application of sophocarpine.

Aloperine-Type Alkaloids with Antiviral and Antifungal Activities from the Seeds of Sophora alopecuroides L

As a continuous flow investigation of novel pesticides from natural quinolizidine alkaloids, the chemical compositions of the seeds of Sophora alopecuroides were thoroughly researched. Fifteen new aloperine-type alkaloids (1-15) as well as six known aloperine-type alkaloids (16-21) were obtained from the extract of S. alopecuroides. The structures of 1-21 were confirmed via HRESIMS, NMR, UV, IR, ECD calculations, and X-ray diffraction. The antiviral activities of 1-21 against tobacco mosaic virus (TMV) were detected following the improved method of half-leaf. Compared with ningnanmycin (protective: 69.7% and curative: 64.3%), 15 exhibited excellent protective (71.7%) and curative (64.6%) activities against TMV. Further biological studies illustrated that 15 significantly inhibited the transcription of the TMV-CP gene and increased the activities of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), and phenylalanine ammonia-lyase (PAL). The antifungal activities of 1-21 against Phytophythora capsica, Botrytis cinerea, Alternaria alternata, and Gibberella zeae were screened according to a mycelial inhibition test. Compound 13 displayed excellent antifungal activity against B. cinerea (EC50: 7.38 μg/mL). Moreover, in vitro antifungal mechanism studies displayed that 13 causes accumulation of reactive oxygen species and finally leads to mycelia cell membrane damage and cell death in vitro.

Bioactive alkaloids from the venom of Dendrobatoidea Cope, 1865: a scoping review

Bioactive compounds derived from secondary metabolism in animals have refined selectivity and potency for certain biological targets. The superfamily Dendrobatoidea is adapted to the dietary sequestration and secretion of toxic alkaloids, which play a role in several biological activities, and thus serve as a potential source for pharmacological and biotechnological applications. This article constitutes a scoping review to understand the trends in experimental research involving bioactive alkaloids derived from Dendrobatoidea based upon scientometric approaches. Forty-eight (48) publications were found in 30 journals in the period of 60 years, between 1962 and 2022. More than 23 structural classes of alkaloids were cited, with 27.63% for batrachotoxins, 13.64% for pyridinics, with an emphasis on epibatidine, 16.36% for pumiliotoxins, and 11.82% for histrionicotoxins. These tests included in vivo (54.9%), in vitro (39.4%), and in silico simulations (5.6%). Most compounds (54.8%) were isolated from skin extracts, whereas the remainder were obtained through molecular synthesis. Thirteen main biological activities were identified, including acetylcholinesterase inhibitors (27.59%), sodium channel inhibitors (12.07%), cardiac (12.07%), analgesic (8.62%), and neuromuscular effects (8.62%). The substances were cited as being of natural origin in the "Dendrobatidae" family, genus "Phyllobates," "Dendrobates," and seven species: Epipedobates tricolor, Phyllobates aurotaenia, Oophaga histrionica, Oophaga pumilio, Phyllobates terribilis, Epipedobates anthonyi, and Ameerega flavopicta. To date, only a few biological activities have been experimentally tested; hence, further studies on the bioprospecting of animal compounds and ecological approaches are needed.

Bitter yet beneficial: The dual role of dietary alkaloids in managing diabetes and enhancing cognitive function

With the rising prevalence of diabetes and its association with cognitive impairment, interest in the use of dietary alkaloids and other natural products has grown significantly. Understanding how these compounds manage diabetic cognitive dysfunction (DCD) is crucial. This comprehensive review explores the etiology of DCD and the effects of alkaloids in foods and dietary supplements that have been investigated as DCD therapies. Data on how dietary alkaloids like berberine, trigonelline, caffeine, capsaicin, 1-deoxynojirimycin, nuciferine, neferine, aegeline, tetramethylpyrazine, piperine, and others regulate cognition in diabetic disorders were collected from PubMed, Research Gate, Web of Science, Science Direct, and other relevant databases. Dietary alkaloids could improve memory in behavioral models and modulate the mechanisms underlying the cognitive benefits of these compounds, including their effects on glucose metabolism, gut microbiota, vasculopathy, neuroinflammation, and oxidative stress. Evidence suggests that dietary alkaloids hold promise for improving cognition in diabetic patients and could open exciting avenues for future research in diabetes management.

Oxymatrine Improves Oxidative Stress-Induced Senescence in HT22 Cells and Mice via the Activation of AMP-Activated Protein Kinase

The accumulation of oxidative stress is one of the important factors causing cellular senescence. Oxymatrine (OM) is a natural quinolizidine alkaloid compound known for its antioxidant effects. This study aimed to investigate the anti-senescence potential of OM through oxidative stress-induced in vitro and in vivo models. By treating 600 μM of H2O2 to the HT22 mouse hippocampal neuronal cell line and by administering 150 mg/kg D-galactose to mice, we generated oxidative stress-induced senescence models. After providing 1, 2, and 4 μg/mL of OM to the HT22 mouse cell line and by administering 50 mg/kg OM to mice, we evaluated the enhancing effects. We evaluated different senescence markers, AMPK activity, and autophagy, along with DCFH-DA detection reaction and behavioral tests. In HT22 cells, OM showed a protective effect. OM, by reducing ROS and increasing p-AMPK expression, could potentially reduce oxidative stress-induced senescence. In the D-Gal-induced senescence mouse model, both the brain and heart tissues recovered AMPK activity, resulting in reduced levels of senescence. In neural tissue, to assess neurological recovery, including anxiety symptoms and exploration, we used a behavioral test. We also found that OM decreased the expression level of receptors for advanced glycation end products (RAGE). In heart tissue, we could observe the restoration of AMPK activity, which also increased the activity of autophagy. The results of our study suggest that OM ameliorates oxidative stress-induced senescence through its antioxidant action by restoring AMPK activity.

Further Quinolizidine Derivatives as Antiarrhythmic Agents- 3

Fourteen quinolizidine derivatives, structurally related to the alkaloids lupinine and cytisine and previously studied for other pharmacological purposes, were presently tested for antiarrhythmic, and other cardiovascular effects on isolated guinea pig heart tissues in comparison to well-established reference drugs. According to their structures, the tested compounds are assembled into three subsets: (a) N-(quinolizidinyl-alkyl)-benzamides; (b) 2-(benzotriazol-2-yl)methyl-1-(quinolizidinyl)alkyl-benzimidazoles; (c) N-substituted cytisines. All compounds but two displayed antiarrhythmic activity that was potent for compounds 4, 1, 6, and 5 (in ascending order). The last compound (N-(3,4,5-trimethoxybenzoyl)aminohomolupinane) was outstanding, exhibiting a nanomolar potency (EC50 = 0.017 µM) for the increase in the threshold of ac-arrhythmia. The tested compounds shared strong negative inotropic activity; however, this does not compromise the value of their antiarrhythmic action. On the other hand, only moderate or modest negative chronotropic and vasorelaxant activities were commonly observed. Compound 5, which has high antiarrhythmic potency, a favorable cardiovascular profile, and is devoid of antihypertensive activity in spontaneously hypertensive rats, represents a lead worthy of further investigation.