Gelsenicine disrupted the intestinal barrier of Caenorhabditis elegans.

Gelsemium elegans Benth. (G. elegans) is a traditional medicinal herb that has anti-inflammatory, analgesic, sedative, and detumescence effects. However, it can also cause intestinal side effects such as abdominal pain and diarrhea. The toxicological mechanisms of gelsenicine are still unclear. The objective of this study was to assess enterotoxicity induced by gelsenicine in the nematodes Caenorhabditis elegans (C. elegans). The nematodes were treated with gelsenicine, and subsequently their growth, development, and locomotion behavior were evaluated. The targets of gelsenicine were predicted using PharmMapper. mRNA-seq was performed to verify the predicted targets. Intestinal permeability, ROS generation, and lipofuscin accumulation were measured. Additionally, the fluorescence intensities of GFP-labeled proteins involved in oxidative stress and unfolded protein response in endoplasmic reticulum (UPRER) were quantified. As a result, the treatment of gelsenicine resulted in the inhibition of nematode lifespan, as well as reductions in body length, width, and locomotion behavior. A total of 221 targets were predicted by PharmMapper, and 731 differentially expressed genes were screened out by mRNA-seq. GO and KEGG enrichment analysis revealed involvement in redox process and transmembrane transport. The permeability assay showed leakage of blue dye from the intestinal lumen into the body cavity. Abnormal mRNAs expression of gem-4, hmp-1, fil-2, and pho-1, which regulated intestinal development, absorption and catabolism, transmembrane transport, and apical junctions, was observed. Intestinal lipofuscin and ROS were increased, while sod-2 and isp-1 expressions were decreased. Multiple proteins in SKN-1/DAF-16 pathway were found to bind stably with gelsenicine in a predictive model. There was an up-regulation in the expression of SKN-1:GFP, while the nuclear translocation of DAF-16:GFP exhibited abnormality. The UPRER biomarker HSP-4:GFP was down-regulated. In conclusion, the treatment of gelsenicine resulted in the increase of nematode intestinal permeability. The toxicological mechanisms underlying this effect involved the disruption of intestinal barrier integrity, an imbalance between oxidative and antioxidant processes mediated by the SKN-1/DAF-16 pathway, and abnormal unfolded protein reaction.

Gelselegine-gelsedine type bisindoles as well as the units from Gelsemium elegans with promoting proliferation of oral mucosa fibroblast cells.

Two undescribed bisindole alkaloids, gelseginedine A (1) and its rearranged gelseginedine B (2), and seven unreported gelselegine-type oxindole alkaloids (3-9) were isolated from the stems and leaves of Gelsemium elegans, together with five known alkaloids (10-14). Compounds 1 and 2 represented the first examples of gelselegine-gelsedine type alkaloids which bridged two units by a double bond. Their structures with absolute configurations were elucidated by means of HRESIMS, NMR and calculational chemistry. The performed bioassay revealed that 14 could promote the proliferation of human oral mucosa fibroblast cells.

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.

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.

Protocol to characterize target components of Gelsemium using an in-house herb database and high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

Currently, the identification of herb metabolites is challenging due to a lack of clear standards. Here, using Gelsemium as an example, we present a protocol for characterizing target components of herbs. This approach utilizes high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry guided by an in-house herb metabolite database based on reported studies and mass spectrometry. We describe steps for creating an in-house database, preparing and detecting samples, processing data, and characterizing compounds. This approach offers a reference for future research on the identification of herb metabolites. For complete details on the use and execution of this protocol, please refer to Liu et al. (2017).1.

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.

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.

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.

Toxicity assessment of gelsenicine and the search for effective antidotes.

BACKGROUND: Gelsenicine, one of the most toxic alkaloids of Gelsemium elegans Benth (G. elegans), causes severe respiratory depression. However, its toxicity mechanisms are yet to be elucidated and no effective antidotes are available. OBJECTIVE: This study aimed to analyse the toxicity characteristics of gelsenicine. METHODS: Both acute and sub-acute toxicities were evaluated. Gelsenicine distribution and elimination in the central nervous system (CNS) and blood were observed. Effective antidotes for gelsenicine poisoning were screened. RESULTS: In the acute toxicity study, gelsenicine was highly toxic, and female rats exhibited greater sensitivity to gelsenicine than male rats (LD50 0.520 mg/kg vs 0.996 mg/kg, respectively). Death was primarily caused by respiratory failure. However, in the sub-acute toxicity study, no significant organ damage was observed. Gelsenicine was easily absorbed from the gastrointestinal tract and penetrated the blood-brain barrier, reaching peak concentrations in the CNS within 15 min and rapidly decreasing thereafter. Flumazenil or diazepam combined with epinephrine reversed gelsenicine toxicity and significantly improved survival rate in mice. CONCLUSIONS: Gelsenicine is a highly toxic substance that affects nerve conduction without causing damage; the potential toxic mechanism is possibly associated with GABAA receptors. Our findings provide insights into the clinical treatment of gelsenicine-related poisoning and its toxicity mechanisms.

New oxindole alkaloids with selective osteoclast inhibitory activity from Gelsemium elegans.

A new alkaloid 14-hydroxygelseziridine (1), along with four known oxindoles (2-5), was isolated and characterized from the well-known toxic medicine Gelsemium elegans. Their structures were elucidated by means of spectroscopic techniques and quantum chemistry calculations. Structurally, new compound 1 has a three membered oxygen ring at N-4/C-20. All compounds were tested for osteoclast (MOC-1) inhibitory activity in vitro. Compound 2 exhibited the selective osteoclast inhibitory activity. Flow cytometry revealed that the apoptosis of osteoclasts induced by 2. Furthermore, the PCR bioassay suggested that compound 2 may activate the apoptotic pathway of osteoclasts by reducing the expression of IL-6 and c-Jun, and increasing caspase 9. This work provided the evidence for the rationality as the traditional treatment for bone related diseases of G. elegans, and shed a new light on its further research.

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.

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.

Metabolic profile and tissue distribution of Humantenirine, an oxindole alkaloid from Gelsemium, after oral administration in rats.

Humantenirine is an active oxindole alkaloid extracted from Gelsemium elegans Benth (G. elegans). In the present study, the metabolites of humantenirine in liver microsomes were first identified by HPLC/QqTOF-MS. Then, the metabolic profile and tissue distribution after oral administration in rats were further investigated. A total of seven metabolites were identified in vitro, and five metabolites in vitro were found in vivo. Moreover, a Ⅱ-phase metabolite was identified first in vivo. The results indicated that humantenirine could be metabolized widely. The parent drug and its metabolites were distributed widely in various tissues and highly in the liver and pancreas. However, the parent drug and its metabolites had low peak intensities in plasma. The elimination of humantenirine occurred rapidly as well, the most unconverted forms of which were found in the kidney. Metabolic pathways, including demethylation, dehydrogenation, oxidation and glucuronidation, were proposed. The present findings may provide a basis for the study of pharmacokinetic characteristics and will contribute to the evaluation of the pharmacology and toxicity of 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.

A network pharmacology-based investigation on the bioactive ingredients and molecular mechanisms of Gelsemium elegans Benth against colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) remains one of the leading causes of cancer-related death worldwide. Gelsemium elegans Benth (GEB) is a traditional Chinese medicine commonly used for treatment for gastrointestinal cancer, including CRC. However, the underlying active ingredients and mechanism remain unknown. This study aims to explore the active components and the functional mechanisms of GEB in treating CRC by network pharmacology-based approaches. METHODS: Candidate compounds of GEB were collected from the Traditional Chinese Medicine@Taiwan, Traditional Chinese Medicines Integrated Database, Bioinformatics Analysis Tool for Molecular mechanism of Traditional Chinese Medicine, and published literature. Potentially active targets of compounds in GEB were retrieved from SwissTargetPrediction databases. Keywords "colorectal cancer", "rectal cancer" and "colon cancer" were used as keywords to search for related targets of CRC from the GeneCards database, then the overlapped targets of compounds and CRC were further intersected with CRC related genes from the TCGA database. The Cytoscape was applied to construct a graph of visualized compound-target and pathway networks. Protein-protein interaction networks were constructed by using STRING database. The DAVID tool was applied to carry out Gene Ontology and Kyoto Encyclopedia of Genes and Genome pathway enrichment analysis of final targets. Molecular docking was employed to validate the interaction between compounds and targets. AutoDockTools was used to construct docking grid box for each target. Docking and molecular dynamics simulation were performed by Autodock Vina and Gromacs software, respectively. RESULTS: Fifty-three bioactive compounds were successfully identified, corresponding to 136 targets that were screened out for the treatment of CRC. Functional enrichment analysis suggested that GEB exerted its pharmacological effects against CRC via modulating multiple pathways, such as pathways in cancer, cell cycle, and colorectal cancer. Molecular docking analysis showed that the representative compounds had good affinity with the key targets. Molecular dynamics simulation indicated that the best hit molecules formed a stable protein-ligand complex. CONCLUSION: This network pharmacology study revealed the multiple ingredients, targets, and pathways synergistically involved in the anti-CRC effect of GEB, which will enhance our understanding of the potential molecular mechanism of GEB in treatment for CRC and lay a foundation for further experimental research.

Offline preparative three-dimensional HPLC for systematic and efficient purification of alkaloids from Gelsemium elegans Benth.

The natural compound library is the most productive source in drug discovery and alkaloids are the most potential drug leads in natural compounds. Presently, systematic purification of alkaloids remains a substantial challenge. In this study, we developed an offline preparative three-dimensional HPLC (3D-HPLC) method to resolve the problem of systematic purification of alkaloids. Ten Gelsemium standards were used in the construction of the method to evaluate several factors, including column selectivity, column loadability and separation orthogonality. The offline 3D-HPLC method achieved great orthogonal selectivity and resolution power using different stationary phases, mobile phases at different pH, and different mobile phase additives. Application of this 3D-HPLC method to Gelsemium elegans Benth. was evaluated, and 24 indole alkaloids were finally isolated, including four new alkaloids and one first-identified in this plant. Moreover, a total of 229 compounds were estimated to be obtained in this plant, almost twice the number of known Gelsemium alkaloids. Therefore, this 3D-HPLC method will be efficient for systematic purification of alkaloids from Gelsemium elegans Benth. and has the potential for alkaloid preparation from other plants.

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.

Toxicokinetics of 11 Gelsemium Alkaloids in Rats by UPLC-MS/MS.

Gelsemium elegans (Gardn. & Champ.) Benth. is a plant belonging to the genus Gelsemium (family Gelsemiaceae), and its main components are alkaloids. It is a Chinese traditional medicinal plant and notoriously known as a highly toxic medicine. However, a method has not yet been found for the simultaneous detection of 11 Gelsemium alkaloids in rat plasma, and the toxicokinetics of 11 Gelsemium alkaloids after intravenous administration has not been reported. In this work, we have developed a sensitive and rapid method of ultraperformance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) for the detection of 11 Gelsemium alkaloids in rat plasma. The toxicokinetic behavior was also investigated, so as to provide a reference of the scientific properties of Gelsemium elegans and improve the efficacy and safety of drugs. Sixty-six Sprague-Dawley rats were randomly divided into 11 groups, six rats in each group. Each group was intravenously given one alkaloid (0.1 mg/kg), respectively. A Waters UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 µm) was used for chromatographic separation. Methanol and water (containing 0.1% formic acid) were used for the mobile phase with gradient elution. Multiple reactions were monitored, and positive electrospray ionization was used for quantitative analysis. The precision was less than 16%, and the accuracy was between 86.9% and 113.2%. The extraction efficiency was better than 75.8%, and the matrix effects ranged from 88.5% to 107.8%. The calibration curves were in the range of 0.1-200 ng/mL, with a correlation coefficient (R 2) greater than 0.995. The UPLC-MS/MS method was successfully applied to the toxicokinetics of 11 Gelsemium alkaloids in rats after intravenous administration (0.1 mg/kg for each alkaloid). The results of the toxicokinetics provide a basis for the pharmacology and toxicology of Gelsemium alkaloids and scientific evidence for the clinical use of Gelsemium alkaloids.

Koumine Alleviates Lipopolysaccharide-Induced Intestinal Barrier Dysfunction in IPEC-J2 Cells by Regulating Nrf2/NF-κB Pathway.

Gelsemium elegans Benth. (G. elegans), a traditional Chinese medicine, has great potential as an effective growth promoter in animals, however, the mechanism of its actin remains unclear. Here, we evaluated the protective effects of koumine extract from G. elegans against lipopolysaccharide (LPS)-induced intestinal barrier dysfunction in IPEC-J2 cells through alleviation of inflammation and oxidative stress. MTT and LDH assays revealed that koumine significantly reduced LPS cytotoxicity. Transepithelial electrical resistance (TEER) and cell monolayer permeability assays showed that koumine treatment attenuated the LPS-induced intestinal barrier dysfunction with no particularly different effects in tight junction proteins such as ZO-1, claudin-1, and occludin. LPS-triggered inflammatory response was also suppressed by koumine, as evidenced by the downregulated inflammatory factors, including TNF-α, IL-6, IL-1ß, NO, iNOS, and COX-2, which was closely connected with the inhibition of NF-κB pathway for the decrease of phosphorylation of IκBα and NF-κB and nuclear translocation of p-p65. Amount of reactive oxygen species (ROS) and MDA induced by LPS was also reduced by koumine through activation of Nrf2 pathway, and increased in the levels of Nrf2 and HO-1 degradation of keap-1 to promote anti-oxidants, including superoxide dismutase (SOD) and catalase (CAT). To summarize, koumine-reduced the oxidative stress and inflammatory reaction triggered by LPS through regulation of the Nrf2/NF-κB signaling pathway and preventing intestinal barrier dysfunction.

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.