Investigation of the Possible Allostery of Koumine Extracted From Gelsemium elegans Benth. And Analgesic Mechanism Associated With Neurosteroids

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.

Reference Genes Screening and Gene Expression Patterns Analysis Involved in Gelsenicine Biosynthesis under Different Hormone Treatments in Gelsemium elegans

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) is an accurate method for quantifying gene expression levels. Choosing appropriate reference genes to normalize the data is essential for reducing errors. Gelsemium elegans is a highly poisonous but important medicinal plant used for analgesic and anti-swelling purposes. Gelsenicine is one of the vital active ingredients, and its biosynthesis pathway remains to be determined. In this study, G. elegans leaf tissue with and without the application of one of four hormones (SA, MeJA, ETH, and ABA) known to affect gelsenicine synthesis, was analyzed using ten candidate reference genes. The gene stability was evaluated using GeNorm, NormFinder, BestKeeper, ∆CT, and RefFinder. The results showed that the optimal stable reference genes varied among the different treatments and that at least two reference genes were required for accurate quantification. The expression patterns of 15 genes related to the gelsenicine upstream biosynthesis pathway was determined by RT-qPCR using the relevant reference genes identified. Three genes 8-HGO, LAMT, and STR, were found to have a strong correlation with the amount of gelsenicine measured in the different samples. This research is the first study to examine the reference genes of G. elegans under different hormone treatments and will be useful for future molecular analyses of this medically important plant species.

Toxic Effects of Koumine on the Early-Life Development Stage of Zebrafish

Koumine is one of the most abundant alkaloids found in Gelsemium elegans, and it has a wide range of pharmacological effects including antitumor, anti-inflammatory, analgesic treatment effects, and antianxiety. However, its high toxicity and unclear mechanism of action have greatly limited the medicinal development and use of koumine. We investigated the toxic effects of koumine on the developmental toxicity and behavioral neurotoxicity of zebrafish embryos and larvae. Embryos at 6 h postfertilization (hpf) were exposed to 12.5, 25, 50, 75, and 100 mg/L of koumine until 120 hpf. Koumine affected the hatching and heartbeats of the embryos. The morphological analysis also revealed many abnormalities, such as shortened bodies, yolk sac edemas, tail malformations, and pericardial edemas. To identify the neurotoxicity of koumine, the behavior of the larvae was measured. Koumine at 50 and 100 mg/L affect the escape response. The embryos exhibited uncoordinated muscle contractions along the body axis in response to touch at 36 hpf. More importantly, we found that the neurotoxicity of koumine is mainly caused by influencing the ACh content and the activity of AChE without impairing motor neuron development. A comprehensive analysis shows that a high concentration of koumine has obvious toxic effects on zebrafish, and the safe concentration of koumine for zebrafish should be less than 25 mg/L. These results will be valuable for better understanding the toxicity of koumine and provide new insights into the application of koumine.

Koumine alleviates rheumatoid arthritis by regulating macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

The imbalance between M1-and M2-polarized macrophages is one of the major pathophysiological changes in RA. Therefore, targeted macrophage polarization may be an effective therapy for RA. Koumine, an alkaloid monomer with the highest content and low toxicity in Gelsemium elegans Benth., has the effect of treating RA by playing an immunomodulatory role by influencing various immune cells. However, whether koumine affects macrophage polarization in RA and the associated molecular mechanisms remain unknown.

AIM OF THE STUDY

To investigate the mechanism of the anti-RA effect of koumine on macrophage polarization.

MATERIALS AND METHODS

The effect of koumine on macrophage polarization was investigated in vivo and in vitro. We first explored the effects of koumine on AIA rats and detected the levels of M1/M2 macrophage polarization markers in the spleen by western blotting. Then, we explored the regulatory effect of koumine on M1/M2 macrophage polarization and the effect on the PI3K/AKT signaling pathway in vitro. Finally, we verified the effects of koumine on macrophage polarization in CIA mice.

RESULTS

We found that koumine alleviated symptoms, including relieving pain, reducing joint redness and swelling in AIA rats and restoring the M1/M2 macrophage balance in vivo. Interestingly, koumine had an inhibitory effect on both M1 and M2 macrophage polarization in vitro, but it had a stronger inhibitory effect on M1 macrophage. In a mixed polarization experiment, koumine mainly inhibited M1 macrophage polarization and had an inhibitory effect on the PI3K/AKT signaling pathway. Finally, we found that koumine had therapeutic effects on CIA mice, regulated macrophage polarization and inhibited the PI3K/AKT signaling pathway.

CONCLUSIONS

Our results reveal that koumine regulates macrophage polarization through the PI3K/AKT signaling pathway. This may be one of the important mechanisms of its anti-RA effect, which provides a theoretical and scientific basis for the possible clinical application of koumine.

Regulation of microglia related neuroinflammation contributes to the protective effect of Gelsevirine on ischemic stroke

Stroke, especially ischemic stroke, is an important cause of neurological morbidity and mortality worldwide. Growing evidence suggests that the immune system plays an intricate function in the pathophysiology of stroke. Gelsevirine (Gs), an alkaloid from Gelsemium elegans, has been proven to decrease inflammation and neuralgia in osteoarthritis previously, but its role in stroke is unknown. In this study, the middle cerebral artery occlusion (MCAO) mice model was used to evaluate the protective effect of Gs on stroke, and the administration of Gs significantly improved infarct volume, Bederson score, neurobiological function, apoptosis of neurons, and inflammation state in vivo. According to the data in vivo and the conditioned medium (CM) stimulated model in vitro, the beneficial effect of Gs came from the downregulation of the over-activity of microglia, such as the generation of inflammatory factors, dysfunction of mitochondria, production of ROS and so on. By RNA-seq analysis and Western-blot analysis, the JAK-STAT signal pathway plays a critical role in the anti-inflammatory effect of Gs. According to the results of molecular docking, inhibition assay, and thermal shift assay, the binding of Gs on JAK2 inhibited the activity of JAK2 which inhibited the over-activity of JAK2 and downregulated the phosphorylation of STAT3. Over-expression of a gain-of-function STAT3 mutation (K392R) abolished the beneficial effects of Gs. So, the downregulation of JAK2-STAT3 signaling pathway by Gs contributed to its anti-inflammatory effect on microglia in stroke. Our study revealed that Gs was benefit to stroke treatment by decreasing neuroinflammation in stroke as a potential drug candidate regulating the JAK2-STAT3 signal pathway.

Koumine induces apoptosis in Cyprinus carpio liver cells by regulating JAK-STAT and p53 signaling pathways

Koumine is an alkaloid with significant anti-anxiety, anticancer cell proliferation, and analgesic activities, and our previous studies have shown that koumine can be used as an immunostimulant in aquaculture, but the molecular mechanism of its effect remains unclear. We fed a basal diet with 0, 0.2, 2, and 20 mg/kg koumine to C. carpio for 10 weeks, and comprehensive studies of the histological and biochemical parameters and transcriptomes of the four groups were performed. Histological results indicated that the number of apoptotic cells in the liver increased with increasing koumine concentration. Compared with those of the control group, the malondialdehyde, superoxide dismutase, catalase, acid phosphatase, alkaline phosphatase, and lactate dehydrogenase levels of the treatment group increased to varying degrees. In total, 100.11 GB of clean data, 4774 DEGs, and 138 differentially expressed genes were obtained from the transcriptome data. Differentially expressed genes were classified into 187 signalling pathways, and the circadian rhythm signalling pathway, the JAK-STAT signalling pathway, the p53 signalling pathway and the PPAR signalling pathway were the top enriched pathways. The qRT-PCR results confirmed that the key genes ifnar1, socs3l, epoa, ghra, cMyc, mcl-1, shisa4, and gtse1 involved in balancing cell proliferation and apoptosis were enriched in these pathways. We discovered that the JAK-STAT and p53 pathways are important targets of koumine. Such information contributes to a better understanding of the potential mechanism by which koumine regulates hepatic immunity as well as to lays the theoretical foundation for its application.

Solid-State Forms of Koumine Hydrochloride: Phase Transformations and the Crystal Structure and Properties of the Stable Form

To investigate the solid-state forms of koumine hydrochloride (KMY), solid form screening was performed, and one amorphous form and five crystalline forms (forms A, B, C, D, and E) were identified by powder X-ray diffraction. Form A was the dominant crystal product, and its crystal structure and packing pattern were determined by single-crystal X-ray diffraction. The crystals displayed an orthorhombic crystal system and symmetry of space group P2₁2₁2₁ with Z' = 1. The amorphous form transformed to form A at 105-120 °C or 75% RH, while forms B, C, D, and E could only be intermediate phases and readily transformed to form A at room temperature. Therefore, the phase transformations of KMY solid-state forms were established. The properties of the amorphous form and form A were further elucidated by applying vibrational spectroscopy, moisture sorption analysis, and thermal analysis. Accordingly, form A, the KMY anhydrate, was found to be the thermodynamically stable form with low hygroscopicity under ambient conditions. These characteristics are crucial in the manufacture and storage of active pharmaceutical ingredients.