Bgugaine, a pyrrolidine alkaloid from Arisarum vulgare, is a strong hepatotoxin in rat and human liver cell cultures

α,β-Desaturation and Formal β-C(sp3)-H Fluorination of N-Substituted Amines: A Late-Stage Functionalization Strategy Enabled by Electrochemistry

Incorporation of C(sp3)-F bonds in biologically active compounds is a common strategy employed in medicinal and agricultural chemistry to tune pharmacokinetic and pharmacodynamic properties. Due to the limited number of robust strategies for C(sp3)-H fluorination of complex molecules, time-consuming de novo syntheses of such fluorinated analogs are typically required, representing a major bottleneck in the drug discovery process. In this work, we present a general and operationally simple strategy for site-specific β-C(sp3)-H fluorination of amine derivatives including carbamates, amides, and sulfonamides, which is compatible with a wide range of functional groups including N-heteroarenes. In this approach, an improved electrochemical Shono oxidation is used to set the site of functionalization via net α,β-desaturation to access enamine derivatives. We further developed a series of new transformations of these enamine intermediates to synthesize a variety of β-fluoro-α-functionalized structures, allowing efficient access to pertinent targets to accelerate drug discovery campaigns.

Recent insights about pyrrolidine core skeletons in pharmacology

To overcome numerous health disorders, heterocyclic structures of synthetic or natural origin are utilized, and notably, the emergence of various side effects of existing drugs used for treatment or the resistance of disease-causing microorganisms renders drugs ineffective. Therefore, the discovery of potential therapeutic agents that utilize different modes of action is of utmost significance to circumvent these constraints. Pyrrolidines, pyrrolidine-alkaloids, and pyrrolidine-based hybrid molecules are present in many natural products and pharmacologically important agents. Their key roles in pharmacotherapy make them a versatile scaffold for designing and developing novel biologically active compounds and drug candidates. This review aims to provide an overview of recent advancements (especially during 2015-2023) in the exploration of pyrrolidine derivatives, emphasizing their significance as fundamental components of the skeletal structure. In contrast to previous reviews that have predominantly focused on a singular biological activity associated with these molecules, this review consolidates findings from various investigations encompassing a wide range of important activities (antimicrobial, antiviral, anticancer, anti-inflammatory, anticonvulsant, cholinesterase inhibition, and carbonic anhydrase inhibition) exhibited by pyrrolidine derivatives. This study is also anticipated to serve as a valuable resource for drug research and development endeavors, offering significant insights and guidance.

Signatures of Co-Deregulated Genes and Their Transcriptional Regulators in Lung Cancer

Despite the significant progress made towards comprehending the deregulated signatures in lung cancer, these vary from study to study. We reanalyzed 25 studies from the Gene Expression Omnibus (GEO) to detect and annotate co-deregulated signatures in lung cancer and in single-gene or single-drug perturbation experiments. We aimed to decipher the networks that these co-deregulated genes (co-DEGs) form along with their upstream regulators. Differential expression and upstream regulators were computed using Characteristic Direction and Systems Biology tools, including GEO2Enrichr and X2K. Co-deregulated gene expression profiles were further validated across different molecular and immune subtypes in lung adenocarcinoma (TCGA-LUAD) and lung adenocarcinoma (TCGA-LUSC) datasets, as well as using immunohistochemistry data from the Human Protein Atlas, before being subjected to subsequent GO and KEGG enrichment analysis. The functional alterations of the co-upregulated genes in lung cancer were mostly related to immune response regulating the cell surface signaling pathway, in contrast to the co-downregulated genes, which were related to S-nitrosylation. Networks of hub proteins across the co-DEGs consisted of overlapping TFs (SOX2, MYC, KAT2A) and kinases (MAPK14, CSNK2A1 and CDKs). Furthermore, using Connectivity Map we highlighted putative repurposing drugs, including valproic acid, betonicine and astemizole. Similarly, we analyzed the co-DEG signatures in single-gene and single-drug perturbation experiments in lung cancer cell lines. In summary, we identified critical co-DEGs in lung cancer providing an innovative framework for their potential use in developing personalized therapeutic strategies.

Asymmetric "Clip-Cycle" Synthesis of Pyrrolidines and Spiropyrrolidines

The development of an asymmetric "clip-cycle" synthesis of 2,2- and 3,3-disubstituted pyrrolidines and spiropyrrolidines, which are increasingly important scaffolds in drug discovery programs, is reported. Cbz-protected bis-homoallylic amines were activated by "clipping" them to thioacrylate via an alkene metathesis reaction. Enantioselective intramolecular aza-Michael cyclization onto the activated alkene, catalyzed by a chiral phosphoric acid, formed a pyrrolidine. The reaction accommodated a range of substitutions to form 2,2- and 3,3-disubstituted pyrrolidines and spiropyrrolidines with high enantioselectivities. The importance of the thioester activating group was demonstrated by comparison to ketone and oxoester-containing substrates. DFT studies supported the aza-Michael cyclization as the rate- and stereochemistry-determining step and correctly predicted the formation of the major enantiomer. The catalytic asymmetric syntheses of N-methylpyrrolidine alkaloids (R)-irnidine and (R)-bgugaine, which possess DNA binding and antibacterial properties, were achieved using the "clip-cycle" methodology.

Reaction of Nitrogen-Radicals with Organometallics Under Ni-Catalysis: N-Arylations and Amino-Functionalization Cascades

Herein, we report a strategy for the generation of nitrogen-radicals by ground-state single electron transfer with organyl-NiI species. Depending on the philicity of the N-radical, two types of processes have been developed. In the case of nucleophilic aminyl radicals direct N-arylation with aryl organozinc, organoboron, and organosilicon reagents was achieved. In the case of electrophilic amidyl radicals, cascade processes involving intramolecular cyclization, followed by reaction with both aryl and alkyl organometallics have been developed. The N-cyclization-alkylation cascade introduces a novel retrosynthetic disconnection for the assembly of substituted lactams and pyrrolidines with its potential demonstrated in the short total synthesis of four venom alkaloids.

Profile on medicinal plants used by the people of North Eastern Morocco: Toxicity concerns

In the North Eastern region of Morocco, many people are interested in medicinal plants and their uses. However, the rationale for the utilization of medicinal plants has remained largely underestimated with little or no scientific data on plant safety. In this paper we attempt to describe and establish a detailed list of current knowledge in relation to the toxicity of these plants and to evaluate the scientific data concerning the harmful effects of the selected natural products. Our approach consists of collecting published data from literature in specialized journals, books and website related to the toxic plants. This research revealed that 89 plant species, retrieved from 287 plants used as medicine in the North-Eastern region of Morocco, are considered toxic or present some kind of toxicity. Our data determines 55 compounds isolated from the plants which are dominated by five groups of toxic compounds: alkaloids followed by glucosides, terpenoids, protides and phenolics. The present work discusses toxicity-related issues arising from the use of medicinal plants by local people. We conclude that the database considered in this study could serve as an important source of information on the toxicity of medicinal plants used by this society.

Chemoselective reductive alkynylation of tertiary amides by Ir and Cu(i) bis-metal sequential catalysis

We report a versatile method for the direct, catalytic reductive alkynylation of tertiary amides to give propargylic amines.

Ameliorative effects of docosahexaenoic acid on the toxicity induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in cultured rat hepatocytes

The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant toxicant that mediates carcinogenic effects associated with oxidative DNA damage. Docosahexaenoic acid (DHA) with antioxidant functions has many biochemical, cellular, and physiological functions for cells. The present study assessed, for the first time, the ameliorative effect of DHA in alleviating the toxicity of TCDD on primary cultured rat hepatocytes (HEPs). In vitro, isolated HEPs were incubated with TCDD (5 and 10 μM) in the presence and absence of DHA (5, 10, and 20 μM) for 48 h. The cell viability was detected by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release. DNA damage was analyzed by liver micronucleus assay and 8-oxo-2-deoxyguanosine (8-OH-dG) level. In addition, total antioxidant capacity (TAC) and total oxidative stress (TOS) were assessed to determine the oxidative injury in HEPs. The results of MTT and LDH assays showed that TCDD decreased cell viability but not DHA. On the basis of increasing treatment concentrations, the dioxin caused significant increases of micronucleated HEPs and 8-OH-dG as compared to control culture. TCDD also led to significant increases in TOS content. On the contrary, in cultures treated with DHA, the level of TAC was significantly increased during treatment in a concentration-dependent fashion. DHA showed therapeutic potential against TCDD-mediated cell viability and DNA damages. As conclusion, this study provides the first evidence that DHA has protective effects against TCDD toxicity on primary cultured rat hepatocytes.

Ameliorative effect of supplementation with L-glutamine on oxidative stress, DNA damage, cell viability and hepatotoxicity induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in rat hepatocyte cultures

The most potent of the dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is a persistent and ubiquitous environmental contaminant. And the health impact of exposure to TCDD is of great concern to the general public. Recent data indicate that L-glutamine (Gln) has antioxidant properties and may influence hepatotoxicity. The objective of the present study was undertaken to explore the effectiveness of Gln in alleviating the hepatotoxicity of TCDD on primary cultured rat hepatocytes. Gln (0.5, 1 and 2 mM) was added to cultures alone or simultaneously with TCDD (0.005 and 0.01 mM). The hepatocytes were treated with TCDD and Gln for 48 h. Then cell viability was detected by [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC), total glutathione (TGSH) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. The DNA damage was also analyzed by liver micronucleus assay (MN) and 8-oxo-2-deoxyguanosine (8-OH-dG). The results of MTT and LDH assays showed that TCDD decreased cell viability but not L-glutamine. TCDD also increased TOS level in rat hepatocytes and significantly decreased TAC and TGSH levels. On the basis of increasing doses, the dioxin in a dose-dependent manner caused significant increases of micronucleated hepatocytes (MNHEPs) and 8-OH-dG as compared to control culture. Whereas, in cultures exposured with Gln alone, TOS levels were not changed and TAC and TGSH together were significantly increased in dose-dependent fashion. The presence of Gln with TCDD modulated the hepatotoxic effects of TCDD on primary hepatocytes cultures. Noteworthy, Gln has a protective effect against TCDD-mediated DNA damages. As conclusion, we reported here an increased potential therapeutic significance of L-glutamine in TCDD-mediated hepatic injury for the first time.

Hepatoprotective potential of astaxanthin against 2,3,7,8-tetrachlorodibenzo-p-dioxin in cultured rat hepatocytes

The purpose of this study was to evaluate the effect of carotenoid astaxanthin (ASTA) on cultured primary rat hepatocytes treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT), lactate dehydrogenase (LDH) activity, 8-oxo-2-deoxyguanosine (8-OH-dG), total antioxidant capacity (TAC), and total oxidative stress (TOS) levels, and liver micronucleus rates. ASTA (2.5, 5, and 10 µM) was added to cultures alone or simultaneously with TCDD (5 and 10 µM) for 48 h. The results of MTT and LDH assays showed that both doses of TCDD caused significant decrease in cell viability. Also, TCDD significantly increased TOS and decreased TAC level in rat hepatocytes. On the basis of increasing doses, the dioxin caused significant increase in micronucleated hepatocytes) and 8-OH-dG level as compared to control culture. The presence of ASTA with TCDD minimized its effects on primary hepatocytes cultures and DNA damages.

The effect of laurel leaf extract against toxicity induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in cultured rat hepatocytes

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a very toxic environmental pollutant that raises great public concern about its impact on human health. Recent studies indicate that laurel leaf extract exhibits antioxidant properties that can counter the toxic effects of certain compounds in the liver. The aim of this study was to assess how effective LE is against the toxicity of TCDD in a primary culture of rat hepatocytes. The extract (50 mg L(-1), 100 mg L(-1), and 200 mg L(-1)) was added to cultures alone or with TCDD (1.61 mg L(-1) and 3.22 mg L(-1)) for 48 hours. Cell viability was measured using the [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and the lactate dehydrogenase (LDH) cytotoxicity assay, while oxidative damage was assessed by measuring total antioxidant capacity (TAC) and total oxidative stress (TOS). DNA damage was also analysed using the micronucleus (MN) assay of the cultured hepatocytes. TCDD alone lowered, and laurel extract had no effect on cell viability. TCDD also increased TOS and significantly decreased TAC. It significantly increased the frequency of micronucleated hepatocytes in a dose-dependent manner. In cultures exposed to LE alone, TOS did not change and TAC significantly increased in a dose-dependent manner. Added to TCDD, laurel countered its toxic effects and showed protective effects against TCDD-mediated DNA damage. This points to the therapeutic potential of laurel against TCDD toxicity in the liver.

Eicosapentaenoic acid protects against 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced hepatic toxicity in cultured rat hepatocytes

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent and ubiquitous environmental contaminant. The health impact of TCDD exposure is of great concern to the general public. Recent reports have implied that eicosapentaenoic acid (EPA) might be a potential chemopreventive agent and influence hepatotoxicity. The aim of the current study was to explore the effectiveness of EPA in alleviating the toxicity of TCDD on primary cultured rat hepatocytes. EPA (5, 10 and 20 μM) was added to cultures alone or simultaneously with TCDD (5 and 10 μM). Rat hepatocytes were treated with TCDD and EPA for 48 h, and then cytotoxicity was detected by [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. The DNA damage was also analyzed by liver micronucleus assay (LMN) and 8-oxo-2-deoxyguanosine (8-OH-dG). The results of MTT and LDH assays showed that TCDD but not EPA decreased cell viability. TCDD also increased TOS level and significantly decreased TAC level in rat hepatocytes in a clear dose dependent manner. On the basis of increasing doses, the dioxin caused significant increases of micronucleated hepatocytes (MNHEPs) and 8-OH-dG as compared to control culture. Whereas, in cultures treated with EPA alone, TOS level did not change and the level of TAC significantly increased. The presence of EPA with TCDD minimized the toxic effects of the dioxin on primary hepatocytes cultures. Noteworthy, EPA has a protective effect against TCDD-mediated DNA damages.

Propolis protects against 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced toxicity in rat hepatocytes

The present experiment was undertaken to determine the effectiveness of propolis in alleviating the toxicity of TCDD on cultured primary rat hepatocytes. Propolis (25, 50 and 100 μM) was added to plain culture or simultaneously with TCDD (5 and 10 μM). The hepatocytes were treated with TCDD and propolis for 48 h. Then cell viability was detected by [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. The DNA damage was also analyzed by liver micronucleus assay (LMN) and 8-oxo-2-deoxyguanosine (8-OH-dG). The results of MTT and LDH assays showed that TCDD decreased cell viability. TCDD also increased TOS level and decreased TAC level in rat hepatocytes. On the basis of increasing doses, the TCDD caused significant increases of micronucleated hepatocytes (MNHEPs) and 8-OH-dG levels as compared to control culture. In cultures treated with propolis alone, cell viability and TOS level were not affected, while the level of TAC was significantly increased in dose-dependent fashion. The presence of propolis with TCDD modulated its toxic effects on primary hepatocytes cultures. Noteworthy, propolis has a protective effect against TCDD-mediated DNA damages.

A concise synthesis of (R)-Bgugaine, a pyrrolidine alkaloid from arisarum vulgare

A new short method for the preparation of (R)-Bgugaine (1) has been described using Wittig condensation of a non-stabilised ylide with N-carboethoxy prolinal followed by reduction of double bond and conversion of N-carboethoxy group to N-methyl.

Cytotoxic effect and electrophysiological activity of S-irniine, a synthesised isomer of the natural R-irniine, on human MRC-5 fibroblasts

Numerous original alkaloids are present in tubers of Arisarum vulgare Targ. a species belonging to the Araceae family known in Morocco for its toxicity. Some previous works deal with the activity of these natural compounds as R-irniine. As the enantioselective total synthesis of irniine has been realised, the R- and S-forms were obtained and this last one could be tested. Thus, a study of the cytotoxicity and the electrophysiological activity of S-irniine was carried out on human MRC-5 fibroblasts. A cytotoxic effect of S-irniine at 40 microg/mL was detected on MRC-5 fibroblasts. An electrophysiological study was also carried out on the MRC-5 cells by using the patch-clamp technique and no effect of this compound at this concentration on the outward potassium current of MRC-5 fibroblasts was observed. Thus, this study showed, as it was for R-irniine, that the cytotoxicity of S-irniine was not explained by an effect on the potassium currents.

Cytotoxic effect and electrophysiological study on human MRC-5 fibroblasts of R-irniine, a natural alkylpyrrolidine alkaloid

R-irniine is a natural 2-alkylpyrrolidine alkaloid extracted from Arisarum vulgare Targ., a species belonging to the Araceae family known in Morocco for its toxicity. Cytotoxic and electrophysiological studies of this compound on human MRC-5 fibroblasts were carried out. Cytotoxic potential of R-irniine was detected on MRC-5 fibroblasts at 40 microg/mL. We carried out the electrophysiological study of this compound on MRC-5 cells by using the technique of patch-clamp in "Whole cell" configuration. R-irniine showed no effect on the outward potassium current of the MRC-5 fibroblasts.

Cytotoxic effect and electrophysiologic activity of (R)-bgugaine, an alkylpyrrolidine alkaloid against MRC-5 fibroblasts

The cytotoxicity and the electrophysiological effects against MRC-5 fibroblasts of 2-alkylpyrrolidine, (-)-R-bgugaine [1], a natural alkaloid, extracted from Arisarum vulgare Targ., (Araceae) were studied. This compound showed a cytotoxic potential against MRC-5 fibroblasts at 10 microg/ml. The electrophysiological study of this molecule on MRC-5 cells was carried out using the technique of patch-clamp and showed that (-)-R-bgugaine [1] has a sub-maximum effect on the outward potassium (current) at the concentration of 1 microM (0.281 microg/ml). In this study we show that R-bgugaine [1] activates the outwards potassium (current) activated by intracellular calcium.

Inhibition of hepatitis B virus production associated with high levels of intracellular viral DNA intermediates in iron-depleted HepG2.2.15 cells

BACKGROUNDS/AIMS

The effects of iron-depletion on hepatitis B virus (HBV) replication were examined in HepG2.2.15 cells.

METHODS

Proliferating cells were iron-depleted with desferrioxamine (DFO), at 20 or 100 microM for 48 h. Levels of viral mRNAs, cytoplasmic DNA replicative intermediates and virion production were examined. A comparative study was performed with hydroxyurea, a specific inhibitor of ribonucleotide reductase.

RESULTS

In desferrioxamine treated cells, virion production is dramatically decreased, while viral replicative intermediates accumulate in the cytoplasm. DFO, like hydroxyurea, blocks cell cycle progression in the G1/S transition or S phase with a corresponding 2-fold increase of viral mRNAs. As expected, hydroxyurea leads to a strong reduction of virion production associated with low levels of intracellular replicative intermediates.

CONCLUSIONS

These results strongly suggest that iron depletion affects the HBV life cycle indirectly through the cell cycle arrest and directly through the inhibition of the viral DNA secretion. They also indicate the need to re-evaluate with caution the iron depletion protocols on HBV infected patients since a decrease of viral markers in the serum following iron-depletion may not reflect a decrease of viral replicative forms, but on the contrary, could be associated with active viral DNA synthesis.

Irniine, a pyrrolidine alkaloid, isolated from Arisarum vulgare can induce apoptosis and/or necrosis in rat hepatocyte cultures

The effects of irniine, a pyrrolidine alkaloid extracted from the tubers of Arisarum vulgare, on rat hepatocyte primary cultures and rat liver epithelial cell line (RLEC) were studied. Cytotoxicity was first evaluated by LDH release, MTT and NR tests and MDA production, while cellular alterations were visualized by electron microscopy and DNA gel-electrophoresis. In hepatocyte and RLEC cultures, a major toxicity appeared at 40 microM of irniine and was demonstrated by an increase in LDH release and decreases in MTT reduction and NR uptake while concentrations lower than 40 microM did not induce significant changes in these parameters. However, we observed an increase in MDA production at 30 microM. Important alterations of the nuclei and mitochondria were also visualized by electron microscopy in cells treated with 50 microM. Using DNA gel-electrophoresis, we demonstrated that irniine at 40 and 50 microM induced DNA damage. All together these results demonstrate that: (1) Irniine induces a significant hepatotoxicity. (2) Irniine toxicity is not mediated by a metabolic derivative since RLEC, which do not contain a monooxygenase system, were also affected by this compound. (3) Irniine induces a significant DNA damage and oxidative stress which leads to cell death by necrosis and/or by apoptosis. Moreover, our data suggest that the alkaloid irniine contained in A. vulgare may be involved in the toxic symptoms observed after medicinal use or consumption of the plant tubers as food both by humans and animals.

Cytotoxic effect and electrophysiological activity of (S)-bgugaine, an alkylpyrrolidine alkaloid against MRC-5 fibroblasts

(+)-S-bgugaine [1], is an alkaloid prepared by enantioselective synthesis. This alkaloid is an isomer of R-bgugaine [2], an alkaloid isolated from Arisarum vulgare, an Araceae toxic plant of Morocco. The cytotoxic effect and the electrophysiological activity of (+)-S-bgugaine [1] against MRC-5 fibroblasts of (+)-S-bgugaine 1, were studied. (+)-S-bgugaine [1] showed a cytotoxic potential at 40 microg/ml against these MRC-5 cells. The electrophysiological study on MRC-5 cells was carried out using the technique of patch-clamp and showed that the activity of compound 1 involved a reduction of outward potassic current at the concentration of 100 microM (28.1 microg/ml) and was accentuated by 200 microM (56.2 microg/ml). In this study we show that S-bgugaine [1], decreases the outward potassic current.