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Gelsemine (GA), the principal alkaloid in Gelsemium elegans Benth, exhibits potent and specific antinociception in chronic pain without the induction of apparent tolerance. However, GA also exerts neurotoxicity and hepatotoxicity when overdosed, and potential detoxification pathways are urgently needed. Cytochrome P450 enzymes (CYPs) are important phase I enzymes involved in the detoxification of xenobiotic compounds. The study aimed to investigate the role of CYPs-mediated metabolism in GA-induced toxicity. Microsomes, chemical special inhibitors and human recombinant CYPs indicated that GA was mainly metabolized by CYP3A4/5. The major metabolite of GA was isolated and identified as 4-N-demethyl-GA by high-resolution mass spectrometry and nuclear magnetic resonance technology. The CYP3A4 inhibitor ketoconazole significantly inhibited the metabolism of GA. This drastically increased GA toxicity which is caused by increasing the level of malondialdehyde and decreasing the level of the superoxide dismutase in mice. In contrast, the CYP3A4 inducer dexamethasone significantly increased GA metabolism and markedly decreased GA toxicity in mice. Notably, in CYP3A4-humanized mice, the toxicity of GA was significantly reduced compared to normal mice. These findings demonstrated that CYP3A4-mediated metabolism is a robust detoxification pathway for GA-induced toxicity.

Background: Gelsemium elegans Benth（G. elegans） is a well-known toxic plant. Alkaloids are main active components of G. elegans. Currently, the metabolism of several alkaloids, such as gelsenicine, koumine, and gelsemine, has been widely studied. However, as one of the most important alkaloids in G. elegans, the metabolism of humantenine has not been studied yet. Methods: In order to elaborate on the in vitro metabolism of humantenine, a comparative analysis of its metabolic profile in human, pig, goat and rat liver microsomes was carried out using high-performance chromatography/quadrupole time-of-flight mass spectrometry (HPLC/QqTOF-MS) for the first time. Results: Totally, ten metabolites of humantenine were identified in liver microsomes from human (HLMs), pig (PLMs), goat (GLMs) and rat (RLMs) based on the accurate MS/MS spectra. Five metabolic pathways of humantenine, including demethylation, dehydrogenation, oxidation, dehydrogenation and oxidation, and demethylation and oxidation, were proposed in this study. There were qualitative and quantitative species differences in the metabolism of humantenine among the four species. Conclusions: The in vitro metabolism of humantenine in HLMs, PLMs, GLMs and RLMs was studied by a sensitive and specific detection method based on HPLC/QqTOF-MS. The results indicated that there were species-related differences in the metabolism of humantenine. This work might be of great significance for the further research and explanation of species differences in terms of toxicological effects of G. elegans.

Gelsemium is a small genus of flowering plants from the family Loganiaceae comprising five species, three of which, Gelsemium sempervirens (L.) J. St.‐Hil., G. elegans Benth and G. rankinii Small, are particularly popular. Compared with other alkaloids from G. elegans, gelsemine, gelsevirine and koumine exhibit equally potent anxiolytic effects and low toxicity. Although the pharmacological activities and metabolism of koumine and gelsemine have been reported in previous studies, the species differences of gelsevirine metabolism have not been well studied. In this study, the metabolism of gelsevirine was investigated by using liver microsomes of humans, pigs, goats and rats by means of HPLC‐QqTOF/MS. The results indicated that the metabolism of gelsevirine in liver microsomes had qualitative and quantitative species differences. Based on the results, the possible metabolic pathways of gelsevirine in liver microsomes were proposed. Investigation of the metabolism of gelsevirine will provide a basis for further studies of the in vivo metabolism of this drug., The metabolism of gelsevirine was investigated using liver microsomes of human, pig, sheep and rat using a HPLC/QqTOF‐MS method. The results indicated that the metabolism of gelsevirine in liver microsomes almost had a certain extent qualitative and quantitative species‐difference. Based on these results, the possible metabolic pathways of gelsevirine in liver microsomes were proposed. The investigation on the metabolism of gelsevirine will facilitate the development and utilization of G. elegans in clinic and its safety evaluation.

Gelsemine is a natural alkaloid extracted from Gelsemium elegans Benth., a traditional Chinese medicinal herb. Gelsemine has been shown to penetrate the brain, and could produce neurological activities, such as anxiolytic and neuralgia-alleviating effects, suggesting that this natural compound might be used for treating nervous system diseases. In this study, we have found, for the first time, that gelsemine at low concentrations (5–10 μg/kg) significantly alleviated cognitive impairments induced by β-amyloid (Aβ) oligomer, a main neurotoxin of Alzheimer’s disease (AD). In addition, gelsemine substantially prevented Aβ oligomer-induced over-activation of microglia and astrocytes, indicating that gelsemine might reduce AD-related gliosis. Consistently, gelsemine inhibited the over-expression of pro-inflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), in the brain of mice. Moreover, gelsemine largely increased the expression of pSer9-glycogen synthase kinase-3β (GSK3β), and decreased the hyper-phosphorylation of tau protein as evidenced by Western blotting analysis. Furthermore, gelsemine prevented Aβ oligomer-induced reduction of PSD-95, a representative post-synaptic protein. All these results directly demonstrated the anti-Aβ oligomer neuroprotective properties of gelsemine, opening a novel perspective for the development of gelsemine-based therapeutics against Aβ-associated neurodegeneration disorders, including AD in particular.

Gelsemium elegans (G. elegans) has been used in traditional Chinese medicine. This plant is highly toxic to humans, but can promote the growth of pigs and goats in the veterinary clinic. It is a very complex mixture containing tens or hundreds of different components. Therefore, multiple-component pharmacokinetic studies of G. elegans are a major challenge due to the lack of authentic standards of the components. The purpose of this study was to investigate the plasma pharmacokinetics of multiple components after a single oral dose of G. elegans in goat using a sensitive ultra-performance liquid chromatography coupled to tandem mass spectrometry method for the simultaneous semiquantification of multiple alkaloids without standards. The method was validated in terms of the specificity, LOD, LOQ, linearity, accuracy, precision and matrix effects. To validate the global pharmacokinetic characteristics, the results obtained from the semiquantitative analysis of three authentic compounds (gelsemine, koumine and humantenmine) were compared with the absolute quantification from our recently published method. The results showed that the two methods had similar analytical results, and the obtained values of Tmax, T1/2 and MRT0−t of the three alkaloids were similar between the two methods. In addition, the values of Cmax and AUC0−t of the three alkaloids after normalization were close to the real values, which indicated that this semiquantitative method could be used in the pharmacokinetic study of multiplecomponents. Then the pharmacokinetic parameters of 23 other G. elegans alkaloids in goats were obtained. The results suggested that the gelsedine-type alkaloids were the major active ingredients that predict and explain the efficacy and toxicity of G. elegans.

Assuming the intentional adulteration of beverages with plant toxins, an LC-MS/MS method for the simultaneous determination of 18 plant toxins (lycorine, galantamine, ricinine, scopolamine, gelsemine, atropine, colchicine, α-solanine, jervine, α-chaconine, veratramine, mesaconitine, digoxin, protoveratrine A, aconitine, hypaconitine, oleandrin, and digitoxin) was developed. As analytical samples, beer, distilled spirits, blend tea, ready-to-drink (RTD) coffee, and fermented milk drink were selected. The extraction and purification of the analytes were performed using modified QuEChERS method. Method validation in terms of intra-day precision, accuracy, and extraction recovery obtained satisfactory results. The calibration curves for the analytes were linear from 5 to 200 ng/mL (r>0.990), which enabled the determination of toxins in even trace amounts.

Gelsemium elegans is a traditional Chinese medicine that has been used to treat eczema, bruises, rheumatoid arthritis and skin ulcers for many years, and alkaloids are its major active and toxic constituents. This study aimed to comprehensively assess the quality of G. elegans samples including different plant parts and origins using ultra high-performance liquid chromatography coupled with photo-diode array and quadrupole time-of-flight mass spectrometry (UHPLC-PDA-QTOF/MS) and high-performance liquid chromatography coupled with UV detector (HPLC-UV). Firstly, the UHPLC-PDA-QTOF/MS approach was developed for the characterization of alkaloids in G. elegans and understanding the differences between multiple groups of samples. Based on the exact mass information, the fragmentation characteristics and the retention time of compounds, 38 alkaloids were identified or tentatively identified. 24 potential chemical markers for differentiating different plant parts of G. elegans were selected through PCA and OPLS/PLS-DA analysis. Secondly, a heatmap visualization was employed for clarifying the distribution of 24 selected alkaloids with high response in the UV. The roots, stems and leaves from Yunnan Province possess relatively consistent alkaloids composition, respectively. Most compounds in the root have a higher content than stems and leaves. Thirdly, a HPLC-UV approach was developed for quantitative analysis of three major alkaloids (gelsemine, koumine and gelsenicine) of G. elegans, and the results showed remarkable variation in the contents of these constituents. While, the contents of three alkaloids fluctuate relatively less in the stem. These results indicated that integrated chemical profiling and quantitative analysis of alkaloids in G. elegans from different plant parts and origins could be assessed by this method, which would establish the foundation for the application of G. elegans.

Background: Of two main alkaloids extracted from Gelsemium, koumine was shown to be a promising analgesic, while gelsemine proved to be deleterious. Many patients suspected to be poisoned by Gelsemium cannot be timely diagnosed due to the lack of UPLC-MS/MS. Additionally, the concentration of alkaloids in humans has never been reported. The aim of this study was to establish a more economical and accessible method using HPLC-UV for diagnosis and quantitative analysis of Gelsemium poisoning. Methods: Plasma spiked with an internal standard, oxcarbazepine, was prepared with solid-phase extraction. Koumine and gelsemine were separated on a C18 column using a mobile phase consisting of methanol, water, and di-n-butylamine (58:42:0.01) pumped at a flow rate of 1.00 mL/min. The detection wavelength was set at 263 nm. Plasma concentrations of two different times were determined for the patients. Results: The calibration curves for both monomers possessed good linearity from 0.05-50 mg/L (r=0.9997 and 0.9999, respectively). The extraction recoveries were greater than 88.5 %. Variation for intraday and interday assays of koumine and gelsemine were less than 8.3% and 7.7%, respectively. The concentrations of the two alkaloids were identified in 5 patients with Gelsemium poisoning by using the established method. Conclusion: The established method by using HPLC-UV is applicable for diagnosis and quantitative analysis of Gelsemium poisoning in such cases. TDM of koumine and gelsemine in patients with Gelsemium poisoning may provide additional information for the clinic to improve rescue strategy.

The honey bee pollen/nectar diet is rich in bioactive phytochemicals and recent studies have demonstrated the potential of phytochemicals to influence honey bee disease resistance. To unravel the role of dietary phytochemicals in honey bee health it is essential to understand phytochemical uptake, bioavailability, and metabolism but presently limited knowledge exists. With this study we aim to build a knowledge foundation. For 5 days, we continuously fed honey bees on eight individual phytochemicals and measured the concentrations in whole and dissected bees by HPLC-MS/MS. Ample phytochemical metabolization was observed, and only 6–30% of the consumed quantities were recovered. Clear differences in metabolization rates were evident, with atropine, aucubin, and triptolide displaying significantly slower metabolism. Phytochemical gut uptake was also demonstrated, and oral bioavailability was 4–31%, with the highest percentages observed for amygdalin, triptolide, and aucubin. We conclude that differences in the chemical properties and structure impact phytochemical uptake and metabolism.

A sensitive, accurate, simple, and rapid analytical LC–MS/MS method was developed for the identification and quantification of koumine, gelsemine, and gelsenicine in human hair. Approximately 10 mg of hair was extracted with methanol by cryogenic grinding. The limits of detection (LODs) ranged from 1 to 5 pg/mg, and the limits of quantitation (LOQs) ranged from 2 to 10 pg/mg. The method was linear over a concentration range from the LOQs to 10000 pg/mg, with the linear correlation (R2) of the calibration curves for all analytes above 0.998. The bias varied from -3.6 to 8.8%, while the intra- and inter-day precision Relative Standard Deviation (RSD) values ranged from 1.8–10.8% and 1.9–9.6%, respectively. Recoveries were within the range of 77.8% to 83.3%, and matrix effects were in the range of 74.3% to 87.4%. The present method was suitable for quantitative determination of koumine, gelsemine, and gelsenicine in human hair from one Gelsemium elegans poisoning case. The highest concentrations of koumine, gelsemine, and gelsenicine in the hair segment corresponding to the period of ingestion were 29.4, 17.6, and 4.7 pg/mg, respectively. To our knowledge, this study is the first to describe hair analysis in a Gelsemium poisoning case and to provide quantitative toxicological findings.

Gelsemine is an active principle and a major alkaloid found in Gelsemium genus of plants belonging to the Loganiaceae family. The aim of the present study was to explore whether gelsemine exerts anxiolytic effects on a mouse model of chronic-unpredictable-mild-stress (CUMS)-induced anxiety-like behaviors. NOD-like receptor protein 3 (NLRP3) inflammasome, downregulated cAMP-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were also evaluated as potential mechanisms. First, gelsemine reversed a CUMS-induced decrease in body-weight gain in mice. Next, gelsemine alleviated CUMS-induced anxiety-like behaviors, as evidenced by the increased distance traveled in the central zone of the open-field test, both the increased percentage of time spent and distance traveled in the light compartment, the increased number of transitions between compartments in the light/dark-transition test, and the increased percentage of entries and time spent in the open arm of the elevated plus-maze. In addition, gelsemine decreased the levels of pro-inflammatory cytokines, including interleukin (IL)-1β and IL-6, in the hypothalamus and hippocampus of CUMS mice. Interestingly, further investigations revealed that gelsemine inhibited the CUMS-induced activation of NLRP3-inflammasome pathways and downregulated CREB and BDNF overexpression in the hypothalamus. In summary, gelsemine alleviated anxiety-like behaviors in the CUMS-induced mouse model. Gelsemine exerted its anxiolytic effects by modulating the NLRP3 and CREB/BDNF pathways.

Rationale Gelsemine has been extensively studied because of its anti-tumor, immunomodulatory, insecticidal itching and other significant effect. However, limited information on the pharmacokinetics and metabolism of gelsemine has been reported. Therefore, the purpose of the present study was to investigate the in vitro metabolism of gelsemine in rat liver S9 by using a rapid and accurate high-performance liquid chromatography/ quadrupole-time-of-flight mass spectrometry (HPLC/QqTOF-MS). Methods The incubation mixture was processed with 15% trichloroacetic acid. Multiple scans of gelsemine metabolites and accurate mass measurements were automatically performed simultaneously through data-dependent acquisition in only a 30-min analysis. The structural elucidations of these metabolites were performed by comparing their changes in accurate molecular masses and product ions with those of the parent drug. Results Five metabolites of gelsemine were identified in rat liver S9. Among of these, four metabolites of gelsemine were identified for the first time. The present results showed that the metabolic pathways of gelsemine are oxidation, demethylation, and dehydrogenation in rat liver S9. Conclusions In this study, metabolites of gelsemine in liver S9 were identified and elucidated firstly using HPLC/QqTOF-MS method. The proposed metabolic pathways of gelsemine in liver S9 will provide a basis for further studies of the in vivo metabolism of gelsemine in animals and humans.

Ethnopharmacological relevance Herbal medicine contains hundreds of natural products, and studying their absorption, metabolism, distribution, and elimination presents great challenges. Gelsemium elegans (G. elegans) is a flowering plants in the Loganiaceae family. The plant is known to be toxic and has been used for many years as a traditional Chinese herbal medicine for the treatment of rheumatoid arthritis, neuropathic pain, spasticity, skin ulcers and cancer. It was also used as veterinary drugs for deworming, promoting animal growth, and pesticides. At present, studies on the metabolism of G. elegans have primarily focused on only a few single available reference ingredients, such as koumine, gelsemine and gelsedine. Material and methods The goal of this work is to elucidate the overall metabolism of whole G. elegans powder in goats using high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC/QqTOF-MS). Results Analyses of plasma, urine and fecal samples identified or tentatively characterized a total of 44 absorbed natural products and 27 related produced metabolites. Gelsedine-type, sarpagine-type and gelsemine-type alkaloids were the compounds with the highest metabolite formation. In the present study, most natural products identified in G. elegans were metabolized through glucuronidation and oxidation. Hydrogenation, dehydrogenation and demethylation also occurred. Conclusion To our knowledge, this is the first report of the metabolite profiling of the G. elegans crude extract in goats, which is of great significance for a safer and more rational application of this herbal medicine.

Two optical isomers, +/− gelsemine (1, 2), together with one known compound were isolated from the whole plant of G. elegans. The structures of the separated constituents were elucidated on 1D and 2D (1H-1H COSY, HMBC, HSQC) NMR spectroscopy and high-resolution mass spectrometry (HRMS). The isolated alkaloids were tested in vitro for cytotoxic potential against PC12 cells by the MTT assay. As a result, (+) gelsemine (compound 1) exhibited cytotoxic activity against PC12 cells with an IC50 value of 31.59 μM, while (−) gelsemine (compound 2) was not cytotoxic.

Background: Gelsemium is a toxic flowering plant of the Gelsemiaceae family. It is used to treat skin diseases in China, and it is an important medicinal and homeopathic plant in North America. Up to now, more than 200 compounds have been isolated and reported from Gelsemium. More than 120 of these are indole alkaloids, including the main components, koumine, gelsemine and humantenmine which produce the pharmacological and toxicological effects of Gelsemium. However, their clinical application their limited by its narrow therapeutic window. Therefore, it is very important to study the metabolism and disposition of indole alkaloids from Gelsemium before their clinical application. This paper reviews all the reports on the metabolism and disposition of alkaloids isolated from Gelsemium at home and abroad. Methods: The metabolism and disposition of alkaloids from Gelsemium were searched by the Web of Science, NCBI, PubMed and some Chinese literature databases. Results: Only koumine, gelsemine and humantenmine have been reported, and few other alkaloids have been described. These studies indicated that the three indole alkaloids are absorbed rapidly, widely distributed in tissues, extensively metabolized and rapidly eliminated. There are species differences in the metabolism of these alkaloids, which is the reason for the differences in their toxicity in animals and humans. Conclusion: This review not only explains the pharmacokinetics of indole alkaloids from Gelsemium but also facilitates further study on their metabolism and mechanism of toxicity.

The present paper describes a novel two-dimensional liquid chromatography (2D-LC) system, which is comprised of a first-dimensional ion exchange chromatography (IEX1) column, trap column, and second-dimensional reversed-phase chromatography (RP2) column system. The biological sample is separated by the first-dimensional LC using an IEX column to remove interferences. The analytes are transferred to the trap column after heart-cutting. Then, the analytes are transferred to the second-dimensional LC using an RP2 column for further separation and ultraviolet detection. This 2D-LC system can offer a large injection volume to provide sufficient sensitivity and exhibits a strong capacity for removing interferences. Here, the determination of three monoterpene indole alkaloids (MIAs; gelsemine, koumine, and humantenmine) from Gelsemium in biological matrices (plasma, tissue, and urine) was used this 2D-LC system. After a rapid and easy sample preparation method based on protein precipitation, the sample was injected into the 2D-LC. The method was developed and validated in terms of the selectivity, LOD, LOQ, linearity, precision, accuracy, and stability. The sample preparation time for the three MIAs was 15 min. The LOD for these compounds was 10 ng/mL, which was lower than the developed HPLC methods. The results showed that this method had good quantitation performance and allowed the determination of gelsemine, koumine, and humantenmine in biological matrices. The method is rapid, exhibits high selectivity, has good sensitivity, and is low-cost, thus making it well-suited for application in the pharmaceutical and toxicological analysis of Gelsemium. Graphical abstract.

We present a case of fatal poisoning from accidental ingestion of Gelsemium elegans (G. elegans), a rarely toxic plant. A 41-year-old man was found dead, at his home, 6 h after drinking homemade herbal liqueur during lunch. Autopsy and routine toxicological analyses identified neither significant pathological findings nor routine poisons. However, a local botanist revealed that the homemade herbal liqueur contained G. elegans, a poisonous plant specific to Asia. To ascertain whether the decedent had ingested G. elegans, we performed liquid chromatography-mass spectrometry (LC-MS) and found two alkaloids (gelsemine and koumine) in his blood, gastric contents, as well as the suspected herbal liqueur. The cause of death was therefore confirmed to be G. elegans poisoning. Case reports of fatal poisoning due to ingestion of G. elegans are quite rare in English. Therefore, the present case broadens the scope on the possibility of death due to ingestion of G. elegans for forensic pathologists and toxicologists.

Background and purpose Gelsemine is one of the principal alkaloids produced by the Gelsemium genus of plants belonging to the Loganiaceae family. The extracts of these plants have been used for many years, for a variety of medicinal purposes. Coincidentally, recent studies have shown that gelsemine exerts anxiolytic and analgesic effects on behavioural models. Several lines of evidence have suggested that these beneficial actions were dependent on glycine receptors, which are inhibitory neurotransmitter-gated ion channels of the CNS. However, it is currently unknown whether gelsemine can directly modulate the function of glycine receptors. Experimental approach We examined the functional effects of gelsemine on glycine receptors expressed in transfected HEK293 cells and in cultured spinal neurons by electrophysiological techniques. Key results Gelsemine directly modulated recombinant and native glycine receptors and exerted conformation-specific and subunit-selective effects. Gelsemine modulation was voltage-independent and was associated with differential changes in the apparent affinity for glycine and in the open probability of the ion channel. In addition, the alkaloid preferentially targeted glycine receptors in spinal neurons and showed only minor effects on GABAA and AMPA receptors. Furthermore, gelsemine significantly diminished the frequency of glycinergic and glutamatergic synaptic events without altering the amplitude. Conclusions and implications Our results provide a pharmacological basis to explain, at least in part, the glycine receptor-dependent, beneficial and toxic effects of gelsemine in animals and humans. In addition, the pharmacological profile of gelsemine may open new approaches to the development of subunit-selective modulators of glycine receptors.

Plant secondary metabolites present naturally in nectar, such as alkaloids, may change the behavioural responses of floral visitors and affect pollination. Some studies have shown that nectar containing low concentrations of these secondary metabolites is preferred by honey bee foragers over pure nectar. However, it remains unclear whether this is caused by dependence or addictive behaviour, a simple taste preference, or by other conditions such as self-medication. In our choice experiment, free-flying bees were presented with artificial flowers holding 20% sucrose containing 0.5−50 μg ml−1 of one of the naturally occurring nectar alkaloids - caffeine, nicotine, senecionine, and gelsemine. Nectar uptake was determined by weighing each flower and comparing the weight to that of the control flower. Our experimental design minimized memorizing and marking; despite this, caffeine was significantly preferred at concentrations 0.5−2 μg ml−1 over control nectar; this preference was not observed for other alkaloids. All of the compounds tested were repellent at concentrations above 5 μg ml−1. We confirmed previous reports that bees exhibit a preference for caffeine, and hypothesize that this is not due only to addictive behaviour but is at least partially mediated by taste preference. We observed no significant preference for nicotine or any other alkaloid.

Rationale Gelsemium elegans Benth. belongs to the family Loganiaceae and is widely distributed in northern America, east Asia, and southeast Asia. It has attracted wide attention for its diverse biological effects and complex architectures. Gelsevirine is one of the major components in G. elegans. Compared with other alkaloids from G. elegans, gelsevirine exhibits equally potent anxiolytic effects but with less toxicity. However, the metabolism of gelsevirine has not been clearly elucidated. Methods The metabolism of gelsevirine was investigated using liver S9 fractions derived from rat liver homogenates by centrifugation at 9000 g. A rapid and accurate high-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (HPLC/QqTOF-MS) method was applied to characterize the gelsevirine metabolites. Results We discovered a total number of four metabolites of gelsevirine. The metabolic pathways of gelsevirine consisted of hydrogenation, N-demethylenation and oxidation in rat liver S9. Conclusions This is the first study on the metabolism of gelsevirine. We proposed possible metabolic pathways of gelsevirine. These findings may warrant future studies of the in vivo metabolism of gelsemine in animals.

This Minireview is focused on an in-depth discussion of comparative strategies to construct the gelsemine and gelsedine classes of the gelsemium alkaloids. This document highlights the diversity of strategies used to access specific motifs found within these targets: a) the fused "[3.2.1]bicycle" (in gelsemine) and "oxabicycle" (in gelsedine class); b) the "piroxindole" moiety with C7 quaternary center; c) the "N-heterocycles" and d) the "THP" moiety with C20 quaternary center (in gelsemine).

Gelsemine is an important toxic substance extracted from Gelsemium elegans, which has a lot of biological functions in cells and organisms, but its toxicity has been rarely reported in Tetrahymena thermophila. In this study, we used the protozoan T. thermophila as an experimental model to investigate the potential toxicity-induced mechanism of gelsemine in the unicellular eukaryote. Our results clearly showed gelsemine inhibited T. thermophila growth in a dose-dependent manner. This exposure also resulted in oxidative stress on T. thermophila cells and antioxidant enzyme levels were significantly altered at high gelsemine levels (p < 0.05). Gelsemine produced a slight apoptotic effect at the highest (0.8 mg/mL) gelsemine level used here (p < 0.05). Furthermore, the toxin-induced DNA damage in a dose-dependent manner. The ultrastructural analysis also revealed mitophagic vacuoles at 0.4 and 0.8 mg/mL levels of gelsemine exposure. Moreover, expressions of oxidative stress-related and MAP kinase genes were significantly changed after exposure to 0.8 mg/mL level of gelsemine (p < 0.05). Altogether, our results clearly show that gelsemine from G. elegans can inhibit the growth via inducing oxidative stress and DNA damage in T. thermophila cells.

Aim: Gelsemine, an alkaloid from the Chinese herb Gelsemium elegans (Gardn & Champ) Benth., is effective in mitigating chronic pain in rats. In the present study we investigated whether the alkaloid improved sleep disturbance, the most common comorbid symptoms of chronic pain, in a mouse model of neuropathic pain. Methods: Mice were subjected to partial sciatic nerve ligation (PSNL). After the mice were injected with gelsemine or pregabalin (the positive control) intraperitoneally, mechanical allodynia and thermal hyperalgesia were assessed, and electroencephalogram (EEG)/electromyogram (EMG) recording was performed. Motor performance of the mice was assessed using rota-rod test. c-Fos expression in the brain was analyzed with immunohistochemical staining. Results: In PSNL mice, gelsemine (2 and 4 mg/kg) increased the mechanical threshold for 4 h and prolonged the thermal latencies for 3 h. Furthermore, gelsemine (4 mg/kg, administered at 6:30 AM) increased non-rapid eye movement (non-REM, NREM) sleep, decreased wakefulness, but did not affect REM sleep during the first 3 h in PSNL mice. Sleep architecture analysis showed that gelsemine decreased the mean duration of wakefulness and increased the total number of episodes of NREM sleep during the first 3 h after the dosing. Gelsemine (4 mg/kg) did not impair motor coordination in PSNL mice. Immunohistochemical study showed that PSNL increased c-Fos expression in the neurons of the anterior cingulate cortex, and gelsemine (4 mg/kg) decreased c-Fos expression by 58%. Gelsemine (4 mg/kg, administered at either 6:30 AM or 8:30 PM) did not produce hypnotic effect in normal mice. Pregabalin produced similar antinociceptive and hypnotic effects, but impaired motor coordination in PSNL mice. Conclusion: Gelsemine is an effective agent for treatment of both neuropathic pain and sleep disturbance in PSNL mice; anterior cingulate cortex might play a role in the hypnotic effects of gelsemine.

Objective To develop an efficient preparative method for the separation of Gelsemium alkaloids from Gelsemium elegans. Methods High-speed counter-current chromatography (HSCCC) with several two-phase solvent systems was investigated for the separation of Gelsemium alkaloids. The purity and structure identification of the purified compounds were performed with HPLC and NMR spectra, respectively. Results In a single operation, 206.6 mg of crude alkaloid sample was separated to yield 28.7 mg of koumine, 24.9 mg of gelsemine, 26.9 mg of humantenine, and 7.2 mg of gelsevirine, with the purities of 97.8%, 95.4%, 97.4%, and 93.5%, respectively. Conclusion A preparative HSCCC method is successfully established for the separation of four Gelsemium alkaloids from G. elegans with a modified two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-0.5% triethylamine-H2O (3:5:3:4).

We have developed a Zincke-aldehyde-based approach to the complex alkaloid gelsemine. It features a key thermal pericyclic cascade that converts a Zincke aldehyde bearing a pendant alkene into a hydroisoindolone product that shares many structural features with the target molecule. Our efforts to convert these intermediates to gelsemine are also discussed.

Gelsemine from Gelsemium elegans Benth is a potential anesthetic and analgesic agent with no physical dependence and opiate addiction. This study was aimed at developing an ultrafast liquid chromatography coupled to tandem mass spectrometry method to quantify gelsemine in rat plasma and tissues. Plasma and tissues were processed with acetonitrile precipitation, and dendrobine was chosen as the internal standard. Sample separation was performed on an ACQUITY HSS T3 column. The mobile phase consisted of acetonitrile and 0.1% formic acid aqueous solution. Multiple reactions monitoring mode was utilized to detect the compounds of interest. The mass spectrometer was operated in the positive ion mode for detection. The MS/MS ion transitions monitored were m/z 323.2→70.5 for gelsemine and 264.2→108.05 for dendrobine, respectively. The calibration curves were linear over the range of 1-500 ng/mL in all biological matrices. The lower limit of quantification for rats plasma and tissues was 1.0 ng/mL. The values for inter- and intraday precision and accuracy were well within the ranges acceptable (< 15%). It was successfully applied to the pharmacokinetic and tissue distribution studies of gelsemine after intravenous doses of 5, 2, and 0.5 mg/kg in rats. These data of gelsemine would be useful for clinical application and further development.

Plant poisonings have left their mark on history and still cause many deaths, whether intentional or accidental. The means to show toxicological evidence of such poisonings should be implemented with great care. This article presents a technique for measuring thirty-nine toxic principles of plant origin in the blood, covering a large amount of toxins from local or exotic plants: α-lobeline, α-solanine, aconitine, ajmaline, atropine, brucine, cephalomannine, colchicine, convallatoxin, cymarine, cytisine, digitoxin, digoxin, emetine, gelsemine, ibogaine, jervine, kavain, lanatoside C, lupanine, mitragynine, neriifolin, oleandrin, ouabain, paclitaxel, physostigmine, pilocarpine, podophyllotoxin, proscillaridin A, reserpine, retrorsine, ricinine, scopolamine, senecionine, sparteine, strophanthidin, strychnine, veratridine and yohimbine. Analysis was carried out using an original ultra-high performance liquid chromatography separation coupled with tandem mass spectrometry detection. Extraction was a standard solid phase extraction performed on Oasis® HLB cartridge. Thirty-four of the thirty-nine compounds were put through a validation procedure. The assay was linear in the calibration curve range from 0.5 or 5 μg/L to 1000 μg/L according to the compounds. The method is sensitive (LOD from 0.1 to 1.6 μg/L). The within-day precision of the assay was less than 22.5% at the LLOQ, and the between-day precision was less than 21.5% for 10 μg/L for all the compounds included. The assay accuracy was in the range of 87.4 to 119.8% for the LLOQ. The extraction recovery and matrix effect ranged from 30 to 106% and from −30 to 14%, respectively. It has proven useful and effective in several difficult forensic cases.

The active components of gelsemium are the alkaloids, which are present in a concentration of about 0.5%. These consist primarily of gelsemine (a highly toxic compound related to strychnine), with lesser amounts of related compounds (gelsemicine, gelsedine, etc). The mode of poisoning is found in both homicide and suicide, and the death rate from the poisoning was high. Poisoning by toxic plants in rural areas is a problem that is worth paying attention to. The survey and analysis of this case of poisoning are conducive to provide guidance for similar events. Language: en

A simple, rapid and sensitive method using UPLC-MS/MS was established and validated for simultaneous determination of gelsemine and koumine in rat plasma after oral administration of Gelsemium elegans Benth extract. Plasma was performed with methanol precipitation and berberine was chosen as the internal standard. Plasma samples were separated on an Acquity UPLC® BEH C18 column (3.0 × 50 mm, 1.7 μm) with gradient elution using acetonitrile and 0.1% formic acid aqueous solution as the mobile phase at a flow rate of 0.4 mL/min. Multiple reaction monitoring mode in positive ion mode was utilized for detection. The calibration curves were linear over the range of 0.2-100 ng/mL for gelsemine and 0.1-50 ng/mL for koumine, with the lower limits of quantification 0.2 and 0.1 ng/mL, respectively. The intra- and inter-precision and accuracy were well within the acceptable ranges. The developed method was successfully applied to an in vivo pharmacokinetic study in rat after oral administration of 10 mg/kg Gelsemium elegans Benth extract.

Three monomers of G. elegans indole alkaloids (gelsemine, koumine and humantenmine) were simultaneously detected in porcine plasma for the first time with the development and validation of a sensitive and reliable LC-ESI-MS/MS method. Using a gradient mobile phase at a constant flow rate of 0.2 mL/min via electrospray ionization (positive ion mode) in a multiple reaction monitoring (MRM) scan, gelsemine, koumine and humantenmine were eluted, separated and detected at an appropriate retention time. The porcine plasma was prepared using protein precipitation with 1% formic acid-acetonitrile: methanol (2:1, v/v). Using matrix-matched calibration curves and weighted least squares linear regression, a good linearity (r2 > 0.99) was achieved with a concentration range of 0.1–200 μg/L for gelsemine, koumine and humantenmine; estimated LOD and LOQ values were 0.10 μg/L and 0.2 μg/L, respectively. The mean of the recoveries was in the range of 82.68–100.35% of porcine plasma at four different levels, and the intra-day and inter-day precision (CV) were lower than 15% with a range of 2.46–8.76% and 2.73–10.83%, respectively. The proposed method has proved to be suitable for accurate, quantitative determination of gelsemine, koumine and humantenmine in porcine plasma.

Humantenmine (HMT), the most toxic compound isolated from Gelsemium elegans Benth, is a well-known active herbal compound. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to estimate the absolute oral bioavailability of HMT in rats. Quantification was performed by multiple reaction monitoring using electrospray ionization (ESI) operated in positive ion mode with transitions of m/z 327.14 → m/z 296.19 for HMT and m/z 323.20 → m/z 236.23 for gelsemine (internal standard, IS). The linear range of the calibration curve was 1-256 nmol/L, with a lower limit of quantification (LLOQ) at 1 nmol/L. The accuracy of HMT ranged from 89.39% to 107.5%, and the precision was within 12.24% (%RSD). Excellent recovery and negligible matrix effect were observed. HMT remained stable during storage, preparation, and analytical procedures. Pharmacokinetics of HMT in rats showed that HMT reached the concentration peak at 12.50 ± 2.74 min with a Cmax of 28.49 ± 6.65 nmol/L, and the corresponding AUC0–t was 1142.42 ± 202.92 nmol/L*min after 200 µg/kg HMT was orally administered to rats. The AUC0–t of HMT given at 20 µg/kg by tail vein administration was 1518.46 ± 192.24 nmol/L*min. The calculated absolute bioavailability of HMT was 7.66%.

The present study investigated the anti-hyperlipidemic proprieties of a natural alkaloid, gelsemine, in a high-fat-fed rabbit model. Animals were randomly divided into five groups and fed normal diet, hypercholesterolemic diet (1% cholesterol), or hypercholesterolemic diet (1% cholesterol) supplemented with gelsemine (1, 5, or 25 mg/kg). After 60 days, serum concentrations of total cholesterol (TC), LDL-C, HDL-C, triglycerides, apolipoproteins A and B, SGOT, SGPT, glucose, and insulin were measured in all experimental groups. Hypercholesterolemic diet resulted in significantly elevated levels of TC, TG, LDL-C, SGOT, and SGPT, and reduced HDL-C compared to the normocholesterolemic diet group. Gelsemine treatment significantly improved lipid profile parameters, affected by hyperlipidemia, while having no effect on the levels of apolipoproteins, glucose, and insulin. Furthermore, gelsemine treatment decreased hyperlipidemia-induced oxidative stress in a dose-dependent manner, as indicated by the increased activity of superoxide dismutase and catalase, and reduction in serum nitric oxide, and malondialdehyde concentrations in hyperlipidemic animals that received gelsemine supplementation. Dietary supplementation with gelsemine may, therefore, reverse the effect of the lipogenic diet on lipid profile and hepatic enzymes in hyperlipidemic rabbits, and protect tissues from oxidative stress, caused by high-fat diet.

Ethnopharmacological relevance Gelsemium sempervirens L. is a traditional medicinal plant mainly distributed in the southeastern of the United States, employed in phytotheraphy and homeopathy as nervous system relaxant to treat various types of anxiety, pain, headache and other ailments. Although animal models showed its effectiveness, the mechanisms by which it might operate on the nervous system are largely unknown. This study investigated for the first time by a real-time PCR technique (RT-PCR Array) the gene expression of a panel of human neurotransmitter receptors and regulators, involved in neuronal excitatory signaling, on a neurocyte cell line. Materials and methods Human SH-SY5Y neuroblastoma cells were exposed for 24 h to Gelsemium sempervirens at 2c and 9c dilutions (i.e. 2 and 9-fold centesimal dilutions from mother tincture) and the gene expression profile compared to that of cells treated with control vehicle solutions. Results Exposure to the Gelsemium sempervirens 2c dilution, containing a nanomolar concentration of active principle gelsemine, induced a down-regulation of most genes of this array. In particular, the treated cells showed a statistically significant decrease of the prokineticin receptor 2, whose ligand is a neuropeptide involved in nociception, anxiety and depression-like behavior. Conclusions Overall, the results indicate a negative modulation trend in neuronal excitatory signaling, which can suggest new working hypotheses on the anxiolytic and analgesic action of this plant.

Ethnopharmacological relevance In the genus Gelsemium , Gelsemium elegans (Gardn. & Champ.) Benth. has been recognized as a toxic plant that is widely distributed in Southeast Asia and has been used as traditional Chinese medicine for the treatment of rheumatoid pain, neuropathic pain, spasticity, skin ulcers and cancers for many years. Gelsemium sempervirens (L.) J.St.-Hil. has been used since the nineteenth century in homeopathy for treating anxiety, neuralgia, migraine and spasmodic disorders, such as asthma and whooping cough in North America. This review aims to provide comprehensive information on the botany, traditional uses, phytochemistry, pharmacological research and toxicology of medicinal plants in the genus Gelsemium . The overall objective is to explore the evidence supporting its ethnopharmacological effectiveness. Materials and methods A literature survey was performed by searching the scientific databases Pubmed, Google Scholar, SciFinder, Scopus, Web of Science and the Chinese CNKI, in addition to traditional Chinese medicine and homeopathic texts for information on Gelsemium . Results Plants of the genus Gelsemium have been used in traditional medicine for the treatment of migraines, neuralgia, sciatica, cancer and various types of sores. Studies into the phytochemical composition of this genus have shown that all of the species are rich sources of monoterpene indole alkaloids and that they have attracted the attention of many researchers due to their markedly diverse and complex architecture. To date, a total of 121 alkaloids have been isolated and identified from the genus. The crude extracts, as well as the monomeric compounds, from the genus possess anti-tumor, analgesic, anxiolytic, anti-inflammatory and immunomodulating pharmacological activities. Conclusion It is evident from the available literature that Gelsemium species possess potential for use as a beneficial therapeutic remedy. However, the analysis of previous pharmacological research suggests that a clear assignment of active molecules and mechanisms of action is remain lacking. Due to their high toxicity, the studies available on toxicity and safety are inadequate for providing information on clinical utilization.

Two optical isomers, +/− gelsemine (1, 2), together with one known compound were isolated from the whole plant of G. elegans. The structures of the separated constituents were elucidated on 1D and 2D (1H-1H COSY, HMBC, HSQC) NMR spectroscopy and high-resolution mass spectrometry (HRMS). The isolated alkaloids were tested in vitro for cytotoxic potential against PC12 cells by the MTT assay. As a result, (+) gelsemine (compound 1) exhibited cytotoxic activity against PC12 cells with an IC50 value of 31.59 μM, while (−) gelsemine (compound 2) was not cytotoxic.

Indole alkaloids are the main bioactive/toxic components in Gelsemium elegans Benth. To determine the distribution and contents of indole alkaloids in its different medicinal parts, a novel and rapid method using ultra-high performance LC (UPLC) with MS/MS has been established and validated with an optimized ultrasound/microwave-assisted extraction method. Four constituents, namely, humantenidine, humantenmine, gelsemine, and koumine, were simultaneously determined in 6 min. Chromatographic separation was achieved on an ultra-high performance LC BEH C18 column with a gradient mobile phase consisting of methanol and water (containing 0.1% formic acid both in methanol and water) at a flow rate of 0.3 mL/min. The detection was performed on a triple quadrupole electrospray MS/MS by positive ion multiple-reaction monitoring mode. All the analytes showed good linearity (r ≥ 0.9934) within a concentration range from 0.1-25 μg/mL with a LOQ of 25-50 ng/mL. The overall intra- and intervariations of four components were

A rapid and simple solvent system screening method was developed for pH-zone-refining counter-current chromatography (CCC) separation, which was much easier to find a suitable solvent system than the traditional method. Using this method, an optimal solvent system composed of hexane–ethyl acetate–methanol–water (3:7:1:9, v/v) was selected for pH-zone-refining CCC separation of alkaloids from the stems of Gelsemium elegans, where 10 mM triethylamine (TEA) was added to the upper organic stationary phase as a retainer and 10 mM hydrochloric acid (HCl) to the aqueous mobile phase as an eluter. As a result, six oxindole alkaloids, 420 mg 19-xo-gelsenicine, 456 mg gelsemine, 723 mg koumine, 379 mg 11-methoxygelsemamide, 342 mg gelsenicine and 318 mg humantenine were successfully purified in one step from 4.5 g crude extract with the purity of over 95%, respectively. The structures of the oxindole alkaloids were identified by ESI-MS, 1H NMR and 13C NMR.

An increasing number of herbal products has been introduced to treat anxiety and depression. Gelsemium elegans Benth (G. elegans) is a well-known herbal plant in Asia. Four major alkaloids (gelsemine, koumine, gelsevirine, and gelsenicine) have been isolated from G. elegans. Recently, interest has arisen to investigate the pharmaceutical potential of G. elegans alkaloids in the context of neuropsychopharmacology.We investigated whether G. elegans alkaloids are capable of producing anxiolytic and antidepressant effects in mouse models. In particular, we examined whether the anxiolytic action of G. elegans alkaloids is due to the agonist effects of glycine receptor in the brain.Two mouse models (elevated plus-maze and light-dark transition model) were used to examine potential anxiolytic effects. Forced swim test and tail suspension test were used to test the antidepressive action of G. elegans alkaloids. Moreover, we also explored the anxiolytic mechanisms of G. elegans alkaloids by intracerebroventricular administration of strychnine, an antagonist of glycine receptor, in the elevated plus-maze.Gelsemine, koumine, and gelsevirine, but not gelsenicine, exhibited potent anxiolytic effects in the two anxiety models. None of the four G. elegans alkaloids exerted antidepressant effects in the two depression models. None of G. elegans alkaloids impaired spontaneous motor activities. The intracerebroventricular administration of strychnine significantly antagonized the anxiolytic effects of gelsemine, koumine, and gelsevirine administrated subcutaneously.Gelsemine, koumine, and gelsevirine could be developed as the treatment of anxiety-related disorders in human patients. Their anxiolytic mechanism may be involved in the agonist action of glycine receptor in the brain.

During the approach to the total synthesis of (+)-gelsemine, two novel spirocyclopentaneoxindole compounds 2 and 3 were obtained. Starting from compound 9, spirocyclopentaneoxindole 3 was efficiently and unexpectedly obtained through a Boc migration–intramolecular Michael cyclization cascade procedure. This intramolecular Michael addition strategy allows conveniently access to complex spirooxindole and spirocyclopentaneoxindole derivatives.

Challenging: (+)-gelsemine was synthesized from (R,R)-aziridine 1 in 25 steps with approximately 1 % overall yield. A multistep, one-pot enol-oxonium cyclization cascade was used to construct, simultaneously, the E ring, F ring, C3 stereocenter, and C7 quaternary stereocenter. This synthesis using the enol-oxonium cyclization reaction as a key step to make the cage structure has demonstrated the proposed biosynthetic pathway of the gelsemine family.

Alkaloids in Gelsemium elegans possess a variety of therapeutic properties, including tumor suppression, analgesic and anti-inflammatory effects. In China, G. elegans has been used for centuries to treat a variety of medical conditions, including chronic pain and skin ulcer. Methods currently used to separate the active components of G. elegans are time-consuming and have low recovery. In the present study, we used pH-zone-refining counter-current chromatography to separate major alkaloids from a crude extract of G. elegans. The two-phase solvent system was methyl tert-butyl ether (MtBE)/acetonitrile/water (3:1.5:4, v/v). Triethylamine (20 mM) was added to the upper organic stationary phase as a retainer. Hydrochloric acid (10 mM) was added to the lower aqueous phase as an eluter. From 1.5 g of crude extract, we obtained 312 mg gelsemine, 420 mg koumine and 195 mg gelsevirine, with purities at 94.8%, 95.9% and 96.7%, respectively, which were determined by HPLC at 256 nm. The chemical identity of the isolated compounds was verified by electrospray ionization-mass spectrometry (ESI-MS), ¹H NMR and ¹³C NMR. These results demonstrated that pH-zone-refining counter-current chromatography is an effective method to separate and purify major alkaloids from G. elegans.

Diet has a significant effect on pathogen infections in animals and the consumption of secondary metabolites can either enhance or mitigate infection intensity. Secondary metabolites, which are commonly associated with herbivore defense, are also frequently found in floral nectar. One hypothesized function of this so-called toxic nectar is that it has antimicrobial properties, which may benefit insect pollinators by reducing the intensity of pathogen infections. We tested whether gelsemine, a nectar alkaloid of the bee-pollinated plant Gelsemium sempervirens, could reduce pathogen loads in bumble bees infected with the gut protozoan Crithidia bombi. In our first laboratory experiment, artificially infected bees consumed a daily diet of gelsemine post-infection to simulate continuous ingestion of alkaloid-rich nectar. In the second experiment, bees were inoculated with C. bombi cells that were pre-exposed to gelsemine, simulating the direct effects of nectar alkaloids on pathogen cells that are transmitted at flowers. Gelsemine significantly reduced the fecal intensity of C. bombi 7 days after infection when it was consumed continuously by infected bees, whereas direct exposure of the pathogen to gelsemine showed a non-significant trend toward reduced infection. Lighter pathogen loads may relieve bees from the behavioral impairments associated with the infection, thereby improving their foraging efficiency. If the collection of nectar secondary metabolites by pollinators is done as a means of self-medication, pollinators may selectively maintain secondary metabolites in the nectar of plants in natural populations.

Secondary metabolites have acute or chronic post-ingestive effects on animals, ranging from death to growth inhibition to reduced nutrient assimilation. 2. Although characterised as toxic, the nectar of Gelsemium sempervirens is not lethal to pollinators, even when the concentration of the nectar alkaloid gelsemine is very high. However, little is known about the sublethal costs of nectar alkaloids. 3. Using a microcolony assay and paired worker bumblebees, the present study measured the effects of artificial nectar containing gelsemine on oocyte development. Oocytes are a sensitive indicator of protein utilisation and general metabolic processes. We also calculated carbohydrate concentrations in the haemolymph to examine energetic costs of gelsemine consumption. 4. High concentrations of gelsemine significantly reduced mean oocyte width in subordinate bees, while dominant bees showed only a trend towards oocyte inhibition. Gelsemine consumption did not reduce carbohydrate concentrations in haemolymph. 5. The cost of ingesting gelsemine may be due to direct toxicity of alkaloids or may be an expense associated with detoxifying gelsemine. Detoxification of alkaloids can require reallocation of resources away from essential metabolic functions like reproduction. The risks associated with nectar alkaloid consumption are tied to both the social and nutritional status of the bee.

The gelsemium plants are highly poisonous but toxicological evaluation of suspected poisoning cases has been hampered by the chemical complexity of the gelsemium toxins involved. A novel liquid chromatography-tandem mass spectrometry protocol was optimized for the collective detection of gelsemine and related alkaloids from Gelsemium elegans. The screening protocol was applied to the clinical investigation of unexplained intoxications following the ingestion of seemingly nontoxic herbs. In three clusters of toxicological emergencies ranging from severe dizziness to respiratory failure, Gelsemium elegans mistaken for various look-alike therapeutic herbs was suspected to be the hidden cause of poisoning. Nine cases of gelsemium poisonings were thus ascertained by the diagnostic urine alkaloid profiles. Gelsemine was sustained as the main urinary marker of Gelsemium exposure.

A tricyclic core structure 2 related to gelsemine 1 was synthesized from an oxabicyclo[3.2.1]octanone 4 by a three-step bridge swapping strategy involving elimination of the bridging ether oxygen and intramolecular Michael addition of a tethered cyanoacetamide unit.

The neurosteroid allopregnanolone (3alpha,5alpha-THP) is well characterized as a potentially therapeutic molecule which exerts important neurobiological actions including neuroprotective, antidepressant, anxiolytic, anesthetic and analgesic effects. We have recently observed that neurons and glial cells of the rat spinal cord (SC) contain various key steroidogenic enzymes such as 5alpha-reductase and 3alpha-hydroxysteroid oxido-reductase which are crucial for 3alpha,5alpha-THP biosynthesis. Furthermore, we demonstrated that the rat SC actively produces 3alpha,5alpha-THP. As the key factors regulating neurosteroid production by nerve cells are unknown and because glycine is one of the pivotal inhibitory neurotransmitters in the SC, we investigated glycine effects on 3alpha,5alpha-THP biosynthesis in the rat SC. Glycine markedly stimulated [(3)H]-progesterone conversion into [(3)H]3alpha,5alpha-THP by SC slices. The alkaloid strychnine, well-known as a glycine receptor (Gly-R) antagonist, blocked glycine stimulatory effect on 3alpha,5alpha-THP formation. Gelsemine, another alkaloid containing the same functional groups as strychnine, increased 3alpha,5alpha-THP synthesis. The stimulatory effects of glycine and gelsemine on 3alpha,5alpha-THP production were additive when the two drugs were combined. These results demonstrate that glycine and gelsemine, acting via Gly-R, upregulate 3alpha,5alpha-THP biosynthesis in the SC. The data also revealed a structure-activity relationship of the analogs strychnine and gelsemine on neurosteroidogenesis. Possibilities are opened for glycinergic agents and gelsemine utilization to stimulate selectively 3alpha,5alpha-THP biosynthetic pathways in diseases evoked by a decreased neurosteroidogenic activity of nerve cells.

The structurally complex alkaloid gelsemine was previously thought to have no significant biological activities, but a recent study has shown that it has potent and specific antinociception in chronic pain. While this molecule has attracted significant interests from the synthetic community, an efficient synthetic strategy is still the goal of many synthetic chemists. Here we report the asymmetric total synthesis of (+)-gelsemine, including a highly diastereoselective and enantioselective organocatalytic Diels–Alder reaction, an efficient intramolecular trans-annular aldol condensation furnishing the prolidine ring and establishing the configuration of the C20 quaternary carbon stereochemical centre. The entire gelsemine skeleton was constructed through a late-stage intramolecular SN2 substitution. The enantiomeric excess of this total synthesis is over 99%, and the overall yield is around 5%., Gelsamine is a naturally occurring alkaloid, whose complex structure makes it an interesting target for total synthesis. Here, the authors report an enantioselective synthesis of (+)-Gelsemine in 5% overall yield, with an enantioselective organocatalytic Diels–Alder reaction as one of the key steps.

(+)-Gelsemine 3 has no particular biological activity, but its intricate architecture continues to inspire the ingenuity of organic synthesis chemists. Yong Qin of Sichuan University devised (Angew. Chem. Int. Ed. 2012, 51, 4909) an enantiospecific synthesis of 3, a key step of which was the cyclization of 1 to 2. The starting material for the synthesis was the inexpensive diethyl tartrate 4, which was converted over six steps into the N-sulfonyl aziridine 5. The addition of 6 was highly regioselective, leading, after N-methylation, to the alkyne 7. After alcohol protection, the sulfonyl group was smoothly removed by sonication with Mg powder in methanol. Addition to acryonitrile then gave 8. Semihydrogenation of 8 set the stage for construction of the lactone 1. The anion of 1, generated by exposure to LDA, cyclized to 2 with significant diastereoselectivity. The lactone of 2 was selectively reduced with Dibal, to give an aldehyde that was protected as the acetal. The exposed primary alcohol was then oxidized to the aldehyde 9. Condensation of 9 with the enolate of 10 followed by dehydration delivered the alkene 11, with the stage set for a second intramolecular nitrile anion addition. In the event, the cyclization of 11 delivered 12, the wrong diastereomer. This was corrected by selenation and oxidation to give an alkene, which was hydrogenated to 13. Exposure to acid deprotected both the MOM group of 13 and the acetal, then promoted cyclization to 14. Reduction of the nitrile to the aldehyde followed by methylenation completed the synthesis of (+)-gelsemine 3. It should be noted that the hydrogenation to form 13 had to be carried out carefully to avoid premature removal of the N-methoxy group. That group was critical for the successful conversion of 13 to 14.

Plants interact simultaneously with a diversity of visitors, including herbivores and pollinators. Correlations among traits associated with herbivory and pollination may constrain the degree to which plants can evolve in response to any one interactor. Using the distylous plant, Gelsemium sempervirens , we tested the hypothesis that traits typically associated with pollination (distyly) and herbivore resistance (secondary compounds) were phenotypically correlated and examined how these traits influenced plant interactions with floral visitors. The flowers of G. sempervirens are visited by pollinators and a nectar robber, and the leaves and flowers express gelsemine, an alkaloid that is deterrent and sometimes toxic to visitors. Using an observational approach across five populations, we found the thrum floral morph (short-styled) expressed more leaf gelsemine than the pin morph (long-styled). Leaf gelsemine concentrations were positively correlated with flower gelsemine; however, there were no correlations between gelsemine and other floral morphological traits. Trait expression influenced pollination more so than robbing. Thrums received two times less pollen than pins. Moreover, across both morphs, pollen receipt was lower in plants that expressed higher levels of leaf gelsemine in two sites. These results imply that traits associated with pollination and herbivore resistance may not be independent.

A detailed examination of the use of aza-Cope rearrangement-Mannich cyclization sequences for assembling the azatricyclo[4.4.0.0(2,8)]decane core of gelsemine is described. Iminium ions and N-acyloxyiminium ions derived from endo-oriented 1-methoxy- or 1-hydroxybicyclo[2.2.2]oct-5-enylamines do not undergo the first step of this sequence, cationic aza-Cope rearrangement, to form cis-hydroisoquinolinium ions. However, the analogous base-promoted oxy-aza-Cope rearrangement does take place to form cis-hydroisoquinolones containing functionality that allows iminium ions or N-acyloxyiminium ions to be generated regioselectively in a subsequent step. Mannich cyclization of cis-hydroisoquinolones prepared in this way efficiently assembles the azatricyclo[4.4.0.0(2,8)]decane unit of gelsemine. Using a sequential base-promoted oxy-aza-Cope rearrangement/Mannich cyclization sequence, gram quantities of azatricyclo[4.4.0.0(2,8)]decanone 18, a central intermediate in our total of (+/-)-gelsemine, were prepared from 3-methylanisole in 12 steps and 16% overall yield.