Gut-Sourced Vasoactive Intestinal Polypeptide Induced by the Activation of α7 Nicotinic Acetylcholine Receptor Substantially Contributes to the Anti-inflammatory Effect of Sinomenine in Collagen-Induced Arthritis

Bioactivities and Mechanisms of Action of Sinomenine and Its Derivatives: A Comprehensive Review

Sinomenine, an isoquinoline alkaloid extracted from the roots and stems of Sinomenium acutum, has been extensively studied for its derivatives as bioactive agents. This review concentrates on the research advancements in the biological activities and action mechanisms of sinomenine-related compounds until November 2023. The findings indicate a broad spectrum of pharmacological effects, including antitumor, anti-inflammation, neuroprotection, and immunosuppressive properties. These compounds are notably effective against breast, lung, liver, and prostate cancers, exhibiting IC50 values of approximately 121.4 nM against PC-3 and DU-145 cells, primarily through the PI3K/Akt/mTOR, NF-κB, MAPK, and JAK/STAT signaling pathways. Additionally, they manifest anti-inflammatory and analgesic effects predominantly via the NF-κB, MAPK, and Nrf2 signaling pathways. Utilized in treating rheumatic arthritis, these alkaloids also play a significant role in cardiovascular and cerebrovascular protection, as well as organ protection through the NF-κB, Nrf2, MAPK, and PI3K/Akt/mTOR signaling pathways. This review concludes with perspectives and insights on this topic, highlighting the potential of sinomenine-related compounds in clinical applications and the development of medications derived from natural products.

Sinomenine ameliorates collagen-induced arthritis in mice by targeting GBP5 and regulating the P2X7 receptor to suppress NLRP3-related signaling pathways

Sinomenine (SIN) is an isoquinoline alkaloid isolated from Sinomenii Caulis, a traditional Chinese medicine used to treat rheumatoid arthritis (RA). Clinical trials have shown that SIN has comparable efficacy to methotrexate in treating patients with RA but with fewer adverse effects. In this study, we explored the anti-inflammatory effects and therapeutic targets of SIN in LPS-induced RAW264.7 cells and in collagen-induced arthritis (CIA) mice. LPS-induced RAW264.7 cells were pretreated with SIN (160, 320, 640 µM); and CIA mice were administered SIN (25, 50 and 100 mg·kg-1·d-1, i.p.) for 30 days. We first conducted a solvent-induced protein precipitation (SIP) assay in LPS-stimulated RAW264.7 cells and found positive evidence for the direct binding of SIN to guanylate-binding protein 5 (GBP5), which was supported by molecular simulation docking, proteomics, and binding affinity assays (KD = 3.486 µM). More importantly, SIN treatment markedly decreased the expression levels of proteins involved in the GBP5/P2X7R-NLRP3 pathways in both LPS-induced RAW264.7 cells and the paw tissue of CIA mice. Moreover, the levels of IL-1β, IL-18, IL-6, and TNF-α in both the supernatant of inflammatory cells and the serum of CIA mice were significantly reduced. This study illustrates a novel anti-inflammatory mechanism of SIN; SIN suppresses the activity of NLRP3-related pathways by competitively binding GBP5 and downregulating P2X7R protein expression, which ultimately contributes to the reduction of IL-1β and IL-18 production. The binding specificity of SIN to GBP5 and its inhibitory effect on GBP5 activity suggest that SIN has great potential as a specific GBP5 antagonist.

Pharmacological mechanisms of sinomenine in anti-inflammatory immunity and osteoprotection in rheumatoid arthritis: A systematic review

BACKGROUND

Sinomenine (SIN) is the main pharmacologically active component of Sinomenii Caulis and protects against rheumatoid arthritis (RA). In recent years, many studies have been conducted to elucidate the pharmacological mechanisms of SIN in the treatment of RA. However, the molecular mechanism of SIN in RA has not been fully elucidated.

PURPOSE

To summarize the pharmacological effects and molecular mechanisms of SIN in RA and clarify the most valuable regulatory mechanisms of SIN to provide clues and a basis for basic research and clinical applications.

METHODS

We systematically searched SciFinder, Web of Science, PubMed, China National Knowledge Internet (CNKI), the Wanfang Databases, and the Chinese Scientific Journal Database (VIP). We organized our work based on the PRISMA statement and selected studies for review based on predefined selection criteria.

OUTCOME

After screening, we identified 201 relevant studies, including 88 clinical trials and 113 in vivo and in vitro studies on molecular mechanisms. Among these studies, we selected key results for reporting and analysis.

CONCLUSIONS

We found that most of the known pharmacological mechanisms of SIN are indirect effects on certain signaling pathways or proteins. SIN was manifested to reduce the release of inflammatory cytokines such as Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), and IL-1β, thereby reducing the inflammatory response, and apparently blocking the destruction of bone and cartilage. The regulatory effects on inflammation and bone destruction make SIN a promising drug to treat RA. More notably, we believe that the modulation of α7nAChR and the regulation of methylation levels at specific GCG sites in the mPGES-1 promoter by SIN, and its mechanism of directly targeting GBP5, certainly enriches the possibilities and the underlying rationale for SIN in the treatment of inflammatory immune-related diseases.

Chukrasia tabularis limonoid plays anti-inflammatory role by regulating NF-κB signaling pathway in lipopolysaccharide-induced macrophages

Background

Chukrasia tabularisis, a well-known tropical tree native to southeastern China, has anti-inflammatory and antioxidant activities, and contains large amounts of limonoids and triterpenoids.

Objective

The aim of this study was to investigate the potential anti-inflammatory activity of limonoids from C. tabularis on lipopolysaccharide (LPS)-mediated RAW264.7 cells.

Methods and results

Using a bioassay-guided approach, the chemical fraction with high anti-inflammatory activity was found and its chemical constituents were investigated. Phytochemical studies on active extracts resulted in the separation of three novel phragmalin limonoids (1-3), together with two known limonoids (4-5) and 11 tirucallane triterpenes (6-16). The activity of these isolated compounds in the production of nitric oxide (NO) on LPS-reated macrophages was evaluated. Limonoid 2 indicated significant anti-inflammatory activities with IC50 value of 4.58 μM. Limonoid 2 notably inhibited the production of NO, interleukin- 6 and tumor necrosis factor-α on macrophage. Signal transduction and activation of STAT and NF-κB activators were effectively blocked by limonoid 2.

Conclusions

These results indicate that limonoid 2 has an anti-inflammatory effect by the inhibiting JAK2/STAT3, iNOS/eNOS, and NF-κB signaling pathways and regulating inflammatory mediators.

A review on pharmacokinetics of sinomenine and its anti-inflammatory and immunomodulatory effects

Autoimmune diseases (ADs), with significant effects on morbidity and mortality, are a broad spectrum of disorders featured by body's immune responses being directed against its own tissues, resulting in chronic inflammation and tissue damage. Sinomenine (SIN) is an alkaloid isolated from the root and stem of Sinomenium acutum which is mainly used to treat pain, inflammation and immune disorders for centuries in China. Its potential anti-inflammatory role for treating immune-related disorders in experimental animal models and in some clinical applications have been reported widely, suggesting an inspiring application prospect of SIN. In this review, the pharmacokinetics, drug delivery systems, pharmacological mechanisms of action underlying the anti-inflammatory and immunomodulatory effects of SIN, and the possibility of SIN as adjuvant to disease-modifying anti-rheumatic drugs (DMARDs) therapy were summarized and evaluated. This paper aims to reveal the potential prospects and limitations of SIN in the treatment of inflammatory and immune diseases, and to provide ideas for compensating its limitations and reducing the side effects, and thus to make SIN better translate to the clinic.

Towards Better Sinomenine-Type Drugs to Treat Rheumatoid Arthritis: Molecular Mechanisms and Structural Modification

Sinomenine is the main component of the vine Sinomenium acutum. It was first isolated in the early 1920s and has since attracted special interest as a potential anti-rheumatoid arthritis (RA) agent, owing to its successful application in traditional Chinese medicine for the treatment of neuralgia and rheumatoid diseases. In the past few decades, significant advances have broadened our understanding of the molecular mechanisms through which sinomenine treats RA, as well as the structural modifications necessary for improved pharmacological activity. In this review, we summarize up-to-date reports on the pharmacological properties of sinomenine in RA treatment, document their underlying mechanisms, and provide an overview of promising sinomenine derivatives as potential RA drug therapies.

Synthesis and biological evaluation of novel sinomenine derivatives as anti-inflammatory and analgesic agent

Sinomenine (SIN) has long been known as an anti-inflammatory drug, while poor efficiency and large-dose treatment had limited its further application. A series of novel SIN derivatives 1–26 were designed and synthesized to improve its anti-inflammatory activity. The anti-inflammatory activity evaluation showed most of the derivatives exhibited enhanced anti-inflammatory activity in vitro compared to SIN. Compound 17 significantly inhibited LPS-induced secretion of pro-inflammatory factors NO (IC₅₀ = 30.28 ± 1.70 μM), and suppressed the expression of iNOS, IL-6 and TNF-α in RAW264.7 cells. Moreover, compound 17 showed excellent anti-inflammatory in mouse paw edema. Immunohistochemistry results revealed that compound 17 exerted anti-inflammatory activity by inhibiting the pro-inflammatory cytokine TNF-α. Furthermore, compound 17 exhibited an analgesic effect in vivo. The results attained in this study indicated that compound 17 had the potential to be developed into an anti-inflammation and analgesic agent.

A series of novel sinomenine derivatives were designed and synthesized. Among them, compound 17 showed strong anti-inflammatory and analgesic activities.

Sinomenine ameliorates septic acute lung injury in mice by modulating gut homeostasis via aryl hydrocarbon receptor/Nrf2 pathway

Sepsis is a systemic inflammatory response syndrome caused by a host's immune response to infection. Acute lung injury (ALI) is one of the most common complications of sepsis with high mortality and morbidity. Recent evidence demonstrated that the 'gut-lung axis' was related to the progression of septic acute lung injury, which regarded gut microbiota and intestinal barrier as two critical factors correlated with acute lung injury. Sinomenine is an isoquinoline alkaloid component extracted from Sinomenium acutum Rehd，et Wils, which has been already reported to have significant anti-inflammatory, immunosuppressive, and anti-arthritis properties. In this research, we observed that sinomenine could repair the lung injury and alleviate inflammatory response induced by cecum ligation and puncture (CLP). Illumine sequencing of 16S rDNA revealed that sinomenine could improve the richness of gut microbiota and modulate the composition of intestinal flora in cecum ligation and puncture mice. Meanwhile, sinomenine could reduce the colon pathological damage and improve the intestine barrier integrity in cecum ligation and puncture mice. We also found that the molecular mechanism of sinomenine's protective effect on intestinal tract was related to the activation of aryl hydrocarbon receptor/nuclear factor erythroid-2 related factor 2（Nrf2）pathway both in vivo and vitro experiments. Collectively, the prevention of septic acute lung injury by sinomenine might be mediated by modulating gut microbiota and restoring intestinal barrier via aryl hydrocarbon receptor/Nrf2-dependent pathway.

Structure elucidation and anti-inflammatory mechanism of difengpienol C, a new neolignan isolated from Illicium difengpi

Illicium difengpi is well-known as its stem barks that have been widely used in the Traditional Chinese Medicine (TCM) for therapy rheumatoid arthritis and traumatic injury. To comprehensive utilization of resources, the phytochemical investigation on the branches and leaves of this plant was carried out, which led to the isolation of an undescribed neolignan along with three known lignans. Their structures were elucidated on the basis of extensive spectroscopic data and the new compound was elucidated as a neolignan possessing a dihydropyran ring formed by a unique conjugation way and named difengpienol C. Difengpienol C showed the strongest anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, which powerfully inhibited nitric oxide (NO), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) production and suppressed the mRNA transcription of inducible nitric oxide synthase (iNOS), IL-6 and TNF-α. Besides, difengpienol C blocked the activation of TLR4/MyD88/NF-κB signaling pathway. Therefore, difengpienol C might be a potent agent for anti-inflammatory drug development, and the non-traditional medicinal parts of Illicium difengpi can be identified as the source of natural anti-inflammatory molecules.

Inhibitory effect of sinomenine on lung cancer cells via negative regulation of α7 nicotinic acetylcholine receptor

Lung cancer is the leading cause of cancer deaths worldwide, with a high morbidity and less than 20% survival rate. Therefore, new treatment strategies and drugs are needed to reduce the mortality of patients with lung cancer. α7 nicotinic acetylcholine receptor (α7 nAChR), as a receptor of nicotine and its metabolites, is a potential target for lung cancer treatment. Our previous studies revealed that sinomenine plays anti-inflammation roles via α7 nAChR and down-regulates the expression of this receptor, thus increasing the inflammatory response. Hence, sinomenine is possibly a natural ligand of this receptor. In the present study, the effects of sinomenine on lung cancer A549 cells and tumor-bearing mice were determined to investigate whether this alkaloid has an inhibitory effect on lung cancer via α7 nAChR. CCK-8 assay, wound-healing test, and flow cytometry were performed for cell proliferation, cell migration, and apoptosis analysis in vitro, respectively. Xenograft mice were used to evaluate the effects of sinomenine in vivo. Results showed that sinomenine decreased cell proliferation and migration abilities but increased the percentage of apoptotic cells. Tumor volume in tumor-bearing mice was significantly reduced after sinomenine treatment compared with that in the vehicle group mice (p < 0.05). Furthermore, the effects of sinomenine were abolished by the α7 nAChR antagonist mecamylamine and the allosteric modulator PNU-120596, but no change occurred when the mice were pretreated with the muscarinic acetylcholine receptor antagonist atropine. Meanwhile, sinomenine suppressed α7 nAChR expression in vitro and in vivo, as well as the related signaling molecules pERK1/2 and ERK1/2 and the transcription factors TTF-1 and SP-1. By contrast, sinomenine up-regulated the expression of another transcription factor, Egr-1. These effects were restricted by mecamylamine and PNU but not by atropine. Results suggested that sinomenine can inhibit lung cancer via α7 nAChR in a negative feedback mode.

Natural products action on pathogenic cues in autoimmunity: Efficacy in systemic lupus erythematosus and rheumatoid arthritis as compared to classical treatments

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), which are characterized by self-perpetuating inflammation and tissue/organ damage, resulting from the failure of lymphocyte auto-tolerance, cause morbidity and mortality worldwide. The current drugs or therapies including conventional non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs), as well as several biologic therapies such as B cell-targeted, T cell-targeted, cytokines-targeted and cytokines receptors-targeted therapy, cannot completely cure SLE and RA, and are always accompanied by unexpected side effects. Therefore, more studies have explored new methods for therapy and found that the herbal medicine as well as its natural products (NPs) exhibited promising therapeutic value through exerting effects of immunomodulation, anti-inflammation, anti-oxidation, and anti-apoptosis, etc. via regulating abnormal responses in kidney, innate and adaptive immune systems, intestine, synoviocytes, as well as bone system including chondrocytes, osteoclasts, joints and paw tissues. In the present review, we will elucidate the current mainstream drugs and therapies for SLE and RA, and summarize the efficacy and mechanisms of NPs in the treatment of SLE and RA based on available findings including in vitro and in vivo animal models, as well as clinical studies, and further analyze the existing challenges, in order to provide comprehensive evidence for improvement of SLE and RA therapy by NPs and to promote management of these two autoimmune diseases.

Sinomenine Attenuates Acetaminophen-Induced Acute Liver Injury by Decreasing Oxidative Stress and Inflammatory Response via Regulating TGF-β/Smad Pathway in vitro and in vivo

Introduction

Liver disease is common and often life-threatening. Sinomenine (SIN) is an active ingredient extracted from  Sinomenium acutum. This study investigated the protective effect and mechanism of sinomenine (SIN) on acetaminophen (APAP)-induced liver injury from in vitro and in vivo.

Methods

In vivo experiments, mice were randomly divided into six groups (n=10): control group, model group, SIN (25 mg/kg) group, SIN (50 mg/kg) group, SIN (100 mg/kg) group and SIN (100 mg/kg) + SRI-011381 group. Alanine transaminases (ALT), aspartate transaminases (AST) and alkaline phosphatase (ALP) were detected. The pathological lesion was measured by HE staining. Apoptosis was measured by TUNEL staining. In vitro experiments, BRL-3A cells were treated with APAP (7.5 mM) and then subjected to various doses of SIN (10, 50 and 100 μg/mL) at 37°C for 24 h. Inflammatory factors and oxidative stress index were measured by ELISA. The expression of proteins was detected by Western blot.

Results

The results showed that compared with the control group, the levels of ALT, AST and ALP in the serum of APAP-induced mice were significantly increased, followed by liver histological damage and hepatocyte apoptosis. Besides, APAP reduced the activity of SOD and GSH-Px, while increasing the content of MDA and LDH. Notably, APAP also promoted the expression of NLRP3, ASC, caspase-1 and IL-1β. Interestingly, SIN treatment dose-dependently reduced APAP-induced liver injury and oxidative stress, inhibited the activation of NLRP3 inflammasomes, and reduced the levels of inflammatory cytokines. In vitro studies have shown that SIN treatment significantly reduced the viability of BRL-3A cells and oxidative stress and inflammation. In addition, the Western blotting analysis showed that SIN inhibited the activation of TGF-β/Smad pathway in a dose-dependent manner in vitro and in vivo. These effects were significantly reversed by TGF-β/Smad activator SRI-011381 or TGF-β overexpression.

Discussion

The study indicates that SIN attenuates APAP-induced acute liver injury by decreasing oxidative stress and inflammatory response via TGF-β/Smad pathway in vitro and in vivo.