Molecular Pharmacology of Gelsemium Alkaloids on Inhibitory Receptors.

Indole alkaloids are the main bioactive molecules of the Gelsemium genus plants. Diverse reports have shown the beneficial actions of Gelsemium alkaloids on the pathological states of the central nervous system (CNS). Nevertheless, Gelsemium alkaloids are toxic for mammals. To date, the molecular targets underlying the biological actions of Gelsemium alkaloids at the CNS remain poorly defined. Functional studies have determined that gelsemine is a modulator of glycine receptors (GlyRs) and GABAA receptors (GABAARs), which are ligand-gated ion channels of the CNS. The molecular and physicochemical determinants involved in the interactions between Gelsemium alkaloids and these channels are still undefined. We used electrophysiological recordings and bioinformatic approaches to determine the pharmacological profile and the molecular interactions between koumine, gelsemine, gelsevirine, and humantenmine and these ion channels. GlyRs composed of α1 subunits were inhibited by koumine and gelsevirine (IC50 of 31.5 ± 1.7 and 40.6 ± 8.2 µM, respectively), while humantenmine did not display any detectable activity. The examination of GlyRs composed of α2 and α3 subunits showed similar results. Likewise, GABAARs were inhibited by koumine and were insensitive to humantenmine. Further assays with chimeric and mutated GlyRs showed that the extracellular domain and residues within the orthosteric site were critical for the alkaloid effects, while the pharmacophore modeling revealed the physicochemical features of the alkaloids for the functional modulation. Our study provides novel information about the molecular determinants and functional actions of four major Gelsemium indole alkaloids on inhibitory receptors, expanding our knowledge regarding the interaction of these types of compounds with protein targets of the CNS.

Recent progress in chemistry and bioactivity of monoterpenoid indole alkaloids from the genus gelsemium: a comprehensive review.

Monoterpenoid indole alkaloids (MIAs) represent a major class of active ingredients from the plants of the genus Gelsemium. Gelsemium MIAs with diverse chemical structures can be divided into six categories: gelsedine-, gelsemine-, humantenine-, koumine-, sarpagine- and yohimbane-type. Additionally, gelsemium MIAs exert a wide range of bioactivities, including anti-tumour, immunosuppression, anti-anxiety, analgesia, and so on. Owing to their fascinating structures and potent pharmaceutical properties, these gelsemium MIAs arouse significant organic chemists' interest to design state-of-the-art synthetic strategies for their total synthesis. In this review, we comprehensively summarised recently reported novel gelsemium MIAs, potential pharmacological activities of some active molecules, and total synthetic strategies covering the period from 2013 to 2022. It is expected that this study may open the window to timely illuminate and guide further study and development of gelsemium MIAs and their derivatives in clinical practice.

New Monoterpenoid Indole Hybrids from Gelsemium elegans with Anti-Inflammatory and Osteoclast Inhibitory Activities.

Gelsegansymines A (1) and B (2), two new indole alkaloids along with six known analogues (3-8) were isolated from the aerial parts of Gelsemium elegans. Their structures were elucidated by means of spectroscopic techniques. Structurally, compounds 1 and 2 possessed the rare cage-like gelsedine skeleton hybrid with bicyclic monoterpenoid. The anti-inflammatory activities of isolated compounds (1-3) were tested on LPS induced RAW264.7 cells. Under the treated concentration without toxicity for cells, the cytokines levels of nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were evaluated by Griess method and enzyme-linked immunosorbent assay (ELISA). The results showed that compounds 1-3 exhibited anti-inflammatory activities with dose-dependent manner range from 12.5 to 50 µmol/L. Furthermore, the inhibitory activities of compounds 1 and 2 on receptor activator of NF-κB ligand (RANKL) induced osteoclast formation were tested in vitro. Compounds 1 and 2 at 5 µmol/L exhibited the significant inhibitory effect on the osteoclastogenesis induced by RANKL. This work reported the anti-inflammatory and osteoclast inhibitory activities of new monoterpenoid indole hybrids, which may inspire the further light on the related traditional application research of G. elegans.

Structural Elucidation and Cytotoxic Activity of New Monoterpenoid Indoles from Gelsemium elegans.

Two new monoterpenoid indole alkaloids, gelselegandines F (1) and G (2), were isolated from the aerial parts of Gelsemium elegans. Their structures were elucidated by means of spectroscopic techniques and quantum chemical calculations. The ECD calculations were conducted at the B3LYP/6-311G(d,p) level and NMR calculations were carried out using the Gauge-Including Atomic Orbitals (GIAO) method. Structurally, the two new compounds possessed rare, cage-like, monoterpenoid indole skeletons. All isolated compounds and the total alkaloids extract were tested for cytotoxicity against four different tumor cell lines. The total alkaloids extract of G. elegans exhibited significant antitumor activity with IC50 values ranging from 32.63 to 82.24 ug/mL. In order to discover anticancer leads from the active extraction, both new indole compounds (1-2) were then screened for cytotoxicity. Interestingly, compound 2 showed moderate cytotoxicity against K562 leukemia cells with an IC50 value of 57.02 uM.

Excretion, Metabolism, and Tissue Distribution of Gelsemium elegans (Gardn. & Champ.) Benth in Pigs.

Gelsemium elegans (Gardn. & Champ.) Benth is a toxic flowering plant in the family Loganiaceae used to treat skin diseases, neuralgia and acute pain. The high toxicity of G. elegans restricts its development and clinical applications, but in veterinary applications, G. elegans has been fed to pigs as a feed additive without poisoning. However, until now, the in vivo processes of the multiple components of G. elegans have not been studied. This study investigates the excretion, metabolism and tissue distribution of the multiple components of G. elegans after feeding it to pigs in medicated feed. Pigs were fed 2% G. elegans powder in feed for 45 days. The plasma, urine, bile, feces and tissues (heart, liver, lung, spleen, brain, spinal cord, adrenal gland, testis, thigh muscle, abdominal muscle and back muscle) were collected 6 h after the last feeding and analyzed using high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Five natural products in plasma, twelve natural products and five metabolites in urine, and three natural products in feces were characterized, suggesting that multiple components from G. elegans were excreted in the urine. However, ten natural products and four metabolites were detected in bile samples, which suggested that G. elegans is involved in enterohepatic circulation in pigs. A total of seven of these metabolites were characterized, and four metabolites were glucuronidated metabolites. Ten natural products and six metabolites were detected in the tissues, which indicates that G. elegans is widely distributed in tissues and can cross the blood-brain barrier. Among the characterized compounds, a highly toxic gelsedine-type alkaloid from G. elegans was the main compound detected in all biological samples. This is the first study of the excretion, metabolism and tissue distribution of multiple components from G. elegans in pigs. These data can provide an important reference to explain the efficacy and toxicity of G. elegans. Additionally, the results of the tissue distribution of G. elegans are of great value for further residue depletion studies and safety evaluations of products of animals fed G. elegans.

Gelstriamine A, a Triamino Monoterpene Indole Alkaloid with a Caged 6/5/7/6/6/5 Scaffold and Analgesic Alkaloids from Gelsemium elegans Stems.

A novel triamino monoterpene indole alkaloid with an unprecedented skeleton, gelstriamine A (1), four new monoterpene indole alkaloids (2-5), and 12 known analogues (6-17) were isolated from Gelsemium elegans. The structures of 1-5 were established using extensive spectroscopic techniques, NMR calculations with iJ/dJ-DP4 and 2D C-H COSY ANNs analysis, ECD calculations, chemical methods, and single crystal X-ray diffraction analysis. Gelstriamine A (1) possesses an unprecedented 6/5/7/6/6/5 heterohexacyclic scaffold bearing a unique hexahydrooxazolo[4,5-b]pyridin-2(3H)-one motif, and a plausible biosynthetic pathway was proposed. All the isolated alkaloids 1-17 showed discernible analgesic activities in an acetic acid-induced writhing test in mice, and N-desmethoxyhumantenine N4-oxide (3) exhibited more potent analgesic activities than those of morphine at doses of 0.04 and 0.2 mg/kg.

Monoterpenoid indole alkaloids from the fruits of Gelsemium elegans and their anti-inflammatory activities.

Two novel monoterpenoid indole alkaloids (MIAs), gelsechizines A-B (1-2), along with four known ones (3-6) were isolated from the fruits of Gelsemium elegans. Compound 1 features a new carbon skeleton with two additional carbon atoms forming a 4-methylpyridine unit. Their structures with absolute configurations were elucidated by NMR, MS, X-ray diffraction and electronic circular dichroism (ECD) calculations. Compounds 1-3 showed significant anti-inflammatory effects in vivo and in vitro, which may be related to the inhibition of the trecruitment of neutrophils and macrophages as well as the secretion of TNF-α and IL-6. Preliminary structure-activity relationship analysis revealed that the ß-N-acrylate moiety plays an important role in the anti-inflammatory effect.

New Monoterpenoid Indoles with Osteoclast Activities from Gelsemium elegans.

The well-known toxic medicine Gelsemium elegans is widely and historically used to treat bone fracture and skin ulcers by the folk people of China. Two new monoterpenoid indole alkaloids, gelselegandines D and E, together with the known analogue gelegamine A were isolated from G. elegans. Their structures were elucidated by means of spectroscopic techniques and quantum chemical calculations. All isolated compounds were tested for the effects on RANKL-induced osteoclast formation. Interestingly, gelselegandine E and gelegamine A, respectively, showed significant promoting and inhibitory activities on osteoclastogenesis, while gelselegandine D had no activity under the same concentration. This work suggested the different configurations for the carbons near the C-19/20 oxygen rings of the isolated compounds may be the key active groups on osteoclast formation and provided the evidence for the rationality as the traditional treatment for bone-related diseases of G. elegans.

Gelsemium elegans Benth: Chemical Components, Pharmacological Effects, and Toxicity Mechanisms.

Gelsemium elegans Benth (GEB), also known as heartbreak grass, is a highly poisonous plant belonging to the family Loganiaceae and genus Gelsemium that has broad application prospects in medicine. This article reviews its chemical components, pharmacological effects, toxicity mechanisms, and research progress in clinical applications in recent years. Indole alkaloids are the main active components of GEB and have a variety of pharmacological and biological functions. They have anti-tumor, anti-inflammatory, analgesic, and immunomodulation properties, with the therapeutic dose being close to the toxic dose. Application of small-dose indole alkaloids fails to work effectively, while high-dose usage is prone to poisoning, aggravating the patient's conditions. Special caution is needed, especially to observe the changes in the disease condition of the patients in clinical practice. In-depth research on the chemical components and mechanisms of GEB is essential to the development of promising lead compounds and lays the foundation for extensive clinical application and safe usage of GEB in the future.

The study of the constituents and source of toxicants in poisonous honey.

A novel method for non-target screening of toxicants in poisonous honey was established in this study. Poisonous honey and nontoxic honey were contrastive detected using liquid chromatography quadrupole-time-of-flight mass spectrometry and analyzed by Mass Profiler Professional Software. 4 poisonous alkaloids were screened out and confirmed by comparison with reference compounds. In order to investigate the source of these poisonous alkaloids, 6 poisonous alkaloids, ubiquitous in Gelsemium elegan, from honey, honeybees, pollen in honeycomb and different organs of Gelsemium elegan, were quantified by liquid chromatography triple-quadrupole tandem mass spectrometry. The results showed that alkaloids composition characteristics in honey, honeybees, and pollen were similar to those in the flower and bud of Gelsemium elegan and significant different from those in leave, stem and root. This result demonstrated that poisonous alkaloids in honey were come from the gathering honey process. This strategy provided an efficient and rapid method for non-target screening of toxicants in food.

Effects of dietary Gelsemium elegans alkaloids on intestinal morphology, antioxidant status, immune responses and microbiota of Megalobrama amblycephala.

Numerous plant extracts used as feed additives in aquaculture have been shown to stimulate appetite, promote growth and enhance immunostimulatory and disease resistance in cultured fish. However, there are few studies on the famous Chinese herbal medicine Gelsemium elegans, which attracts our attention. In this study, we used the Megalobrama amblycephala to investigate the effects of G. elegans alkaloids on fish intestinal health after diet supplementation with 0, 5, 10, 20 and 40 mg/kg G. elegans alkaloids for 12 weeks. We found that dietary G. elegans alkaloids at 40 mg/kg improved intestinal morphology by increasing villus length, muscle thickness and villus number in the foregut and midgut and muscle thickness in the hindgut (P < 0.05). These alkaloids also significantly improved intestinal antioxidant capabilities by increasing superoxide dismutase, catalase, total antioxidant capacity and malondialdehyde levels and up-regulated intestinal Cu/Zn-SOD and Mn-SOD (P < 0.05) at 20 and 40 mg/kg. Dietary G. elegans alkaloids improved intestinal immunity via up-regulating the pro-inflammatory cytokines IL-1ß, IL-8, TNF-α and IFN-α and down-regulating expression of the anti-inflammatory cytokines IL-10 and TGF-ß (P < 0.05) at 20 and 40 mg/kg. The expression of Toll-like receptors TRL1, 3, 4 and 7 were also up-regulated in intestine of M. amblycephala (P < 0.05). In intestinal microbiota, the abundance of Proteobacteria was increased while the Firmicutes abundance was decreased at phylum level after feeding the alkaloids (P < 0.05). The alkaloids also increased the abundance of the probiotic Rhodobacter and decreased the abundance of the pathogenic Staphylococcus at genus level (P < 0.05). In conclusion, dietary G. elegans alkaloid supplementation promoted intestine health by improving intestine morphology, immunity, antioxidant abilities and intestinal microbiota in M. amblycephala.

Effects of dietary Gelsemium elegans alkaloids on growth performance, immune responses and disease resistance of Megalobrama amblycephala.

The present study aim to investigate the effects of dietary Gelsemium elegans alkaloids supplementation in Megalobrama amblycephala. A basal diet supplemented with 0, 5, 10, 20 and 40 mg/kg G. elegans alkaloids were fed to M. amblycephala for 12 weeks. The study indicated that dietary 20 mg/kg and 40 mg/kg G. elegans alkaloids supplementation could significantly improve final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) (P < 0.05). The 20 mg/kg and 40 mg/kg G. elegans alkaloids groups showed significantly higher whole body and muscle crude protein and crude lipid contents compared to the control group (P < 0.05). The amino acid contents in muscle were also significantly increased in 20 mg/kg and 40 mg/kg groups (P < 0.05). Dietary 40 mg/kg G. elegans alkaloids had a significant effect on the contents of LDH, AST, ALT, ALP, TG, TC, LDL-C, HDL-C, ALB and TP in M. amblycephala (P < 0.05). Fish fed 20 mg/kg and 40 mg/kg dietary G. elegans alkaloids showed significant increase in complement 3, complement 4 and immunoglobulin M contents. The liver antioxidant enzymes (SOD, CAT and T-AOC) and MDA content significantly increased at 20 mg/kg and 40 mg/kg G. elegans alkaloids supplement (P < 0.05). The mRNA levels of immune-related genes IL-1ß, IL8, TNF-α and IFN-α were significantly up-regulated, whereas TGF-ß and IL10 genes were significantly down-regulated in the liver, spleen and head kidney of fish fed dietary supplementation with 20 mg/kg and 40 mg/kg G. elegans alkaloids. After challenge with Aeromonas hydrophila, significant higher survival rate was observed at 20 mg/kg and 40 mg/kg G. elegans alkaloids supplement (P < 0.05). Therefore, these results indicated that M. amblycephala fed a diet supplemented with 20 mg/kg and 40 mg/kg G. elegans alkaloids could significantly promote its growth performance, lipids and amino acids deposition, immune ability and resistance to Aeromonas hydrophila.

CYP3A4/5 mediates the metabolic detoxification of humantenmine, a highly toxic alkaloid from Gelsemium elegans Benth.

Gelsemium elegans Benth., a well-known toxic herbal plant, is widely used to treat rheumatic arthritis, inflammation and other diseases. Gelsemium contains humantenmine (HMT), which is an important bioactive and toxic alkaloid. Cytochrome P450 enzymes (CYPs) play important roles in the elimination and detoxification of exogenous substances. This study aimed to investigate the roles of CYPs in the metabolism and detoxification of HMT. First, metabolic studies were performed in vitro by using human liver microsomes, selective chemical inhibitors and recombinant human CYPs. Results indicated that four metabolites, including hydroxylation and oxidation metabolites, were found in human liver microsomes and identified based on their high-resolution mass spectrum. The isoform responsible for HMT metabolism was mainly CYP3A4/5. Second, the toxicity of HMT on L02 cells in the presence of the nicotinamide adenine dinucleotide phosphate system (NADPH) was significantly less than that without NADPH system. A CYP3A4/5 activity inhibition model was established by intraperitoneally injecting ketoconazole in mice and used to evaluate the role of CYP3A4/5 in HMT detoxification. In this model, the 14-day survival rate of the mice decreased to 17% after they were intragastrically treated with HMT, along with hepatic injury and increasing alanine aminotransferase (ALT) /aspartate aminotransferase (AST) levels. Overall, CYP3A4/5 mediated the metabolism and detoxification of HMT.

Protective Effect of Koumine, an Alkaloid from Gelsemium Sempervirens, on Injury Induced by H2O2 in IPEC-J2 Cells.

Medicinal herbal plants have been commonly used for intervention in different diseases and improvement of health worldwide. Koumine, an alkaloid monomer found abundantly in Gelsemium plants, can be effectively used as an antioxidant. The purpose of this study was to evaluate the potential protective effect of koumine against hydrogen peroxide (H2O2)-induced oxidative stress and apoptosis in porcine intestinal epithelial cell line (IPEC-J2 cells). MTT assays showed that koumine significantly increased cell viability in H2O2-mediated IPEC-J2 cells. Preincubation with koumine ameliorated H2O2-medicated apoptosis by decreasing reactive oxygen species (ROS) production, and efficiently suppressed the lactate dehydrogenase (LDH) release and malondialdehyde (MDA) production. Moreover, a loss of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) activities was restored to normal level in H2O2-induced IPEC-J2 cells upon koumine exposure. Furthermore, pretreatment with koumine suppressed H2O2-mediated loss of mitochondrial membrane potential, caspase-9 and caspase-3 activation, decrease of Bcl-2 expression and elevation of Bax expressions. Collectively, the results of this study indicated that koumine possesses the cytoprotective effects in IPEC-J2 cells during exposure to H2O2 by suppressing production of ROS, inhibiting the caspase-3 activity and influencing the expression of Bax and Bcl-2. Koumine could potentially serve as a protective effect against H2O2-induced apoptosis.

Floral Scent Variation in the Heterostylous Species Gelsemium sempervirens.

Gelsemium sempervirens (L.) W.T. Aiton, a distylous woody vine of the family Gelsemiaceae, produces sweetly fragrant flowers that are known for the toxic alkaloids they contain. The composition of this plant's floral scent has not previously been determined. In this study, the scent profiles of 74 flowers obtained from six different wild and cultivated populations of G. sempervirens were measured by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). There were 81 volatile organic compounds identified and characterized as benzenoids, terpenoids, fatty acid derivatives, and yeast associated compounds. The most abundant compound was benzaldehyde (23-80%) followed by ethanol (0.9-17%), benzyl benzoate (2-15%), 4-anisaldehyde (2-11%), (Z)-α-ocimene (0-34%), and α-farnesene (0.1-16%). The impacts of geographic location, population type (wild or cultivated), and style morph (L = long, S = short) on scent profile were investigated. The results showed no relationship between geographic location or population type and volatile organic compounds (VOC) profile, but did show a significant scent profile difference between L and S morphs based on non-metric multidimensional scaling (NMDS) using Bray-Curtis similarity indices. The L morphs contained higher amounts of benzenoids and the S morphs contained higher amounts of terpenoids in their scent profiles. The L morphs also produced a higher total abundance of scent compounds than the S morphs. This study represents the first floral scent determination of G. sempervirens finding significant variation in scent abundance and composition between style morphs.

The Difference in Cytotoxic Activity between Two Optical Isomers of Gelsemine from Gelsemium elegans Benth. on PC12 Cells.

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.

[Difference of alkaloid components between old stems and tender stems of Gelsemium elegans].

This study aimed to comprehensively assess the difference of alkaloid components between old stems and tender stems of Gelsemium elegans by using ultra high-performance liquid chromatography coupled with photo-diode array and quadrupole time-of-flight mass spectrometry( UPLC-Q-TOF/MS~E) and high-performance liquid chromatography coupled with UV detector( HPLC-UV). Firstly,the different components in old stems and tender stems were analyzed by UHPLC-Q-TOF/MSEcombined with principal component analysis( PCA) and orthogonal partial least squares discriminant analysis( OPLS-DA),respectively. As a result,17 major different components were found. At the same time,the distribution of these alkaloids in old stems and tender stems was determined,and the alkaloids with higher polarity are relatively higher in the tender stems,while the old stems are in the opposite case. In addition,three main components in the G. elegans were quantified by HPLC-UV. The results showed that the contents of koumine and humantenmine in old stems were higher than those in tender stems,and the content of gelsemine in tender stems was relatively high. This study systematically evaluated the differences of alkaloids between the old stems and tender stems of G. elegans,and quantified the main three alkaloids. It laid the foundation of the safe and effective application of G. elegans.

Recent Syntheses and Strategies toward Polycyclic Gelsemium Alkaloids.

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).

Phenotypic selection on floral traits in an urban landscape.

Native species are increasingly living in urban landscapes associated with abiotic and biotic changes that may influence patterns of phenotypic selection. However, measures of selection in urban and non-urban environments, and exploration of the mechanisms associated with such changes, are uncommon. Plant-animal interactions have played a central role in the evolution of flowering plants and are sensitive to changes in the urban landscape, and thus provide opportunities to explore how urban environments modify selection. We evaluated patterns of phenotypic selection on the floral and resistance traits of Gelsemium sempervirens in urban and non-urban sites. The urban landscape had increased florivory and decreased pollen receipt, but showed only modest differences in patterns of selection. Directional selection for one trait, larger floral display size, was stronger in urban compared to non-urban sites. Neither quadratic nor correlational selection significantly differed between urban and non-urban sites. Pollination was associated with selection for larger floral display size in urban compared to non-urban sites, due to the differences in the translation of pollination into seeds rather than pollinator selectivity. Thus, our data suggest that urban landscapes may not result in sweeping differences in phenotypic selection but rather modest differences for some traits, potentially mediated by species interactions.

Gelsecorydines A-E, Five Gelsedine-Corynanthe-Type Bisindole Alkaloids from the Fruits of Gelsemium elegans.

Five monoterpenoid bisindole alkaloids with new carbon skeletons, gelsecorydines A-E (1-5), together with their biogenetic precursors were isolated from the fruits of Gelsemium elegans. Compounds 1-5 represent the first examples of heterodimeric frameworks composed of a gelsedine-type alkaloid and a modified corynanthe-type one. Notably, compound 2 featured an unprecedented caged skeleton with a 6/5/7/6/5/6 heterohexacyclic ring system, which possessed a pyridine ring that linked the two monomers. Their structures and absolute configurations were elucidated by spectroscopic analysis, X-ray diffraction, and electronic circular dichroism (ECD) calculation. A plausible biosynthetic pathway for compounds 1-5 is proposed. Compounds 1, 3, 4, and 5 exhibited a significant inhibitory effect against nitric oxide (NO) production in macrophages.