Norisoboldine, an alkaloid compound isolated from Radix Linderae, inhibits synovial angiogenesis in adjuvant-induced arthritis rats by moderating Notch1 pathway-related endothelial tip cell phenotype

Norisoboldine, a Natural Isoquinoline Alkaloid, Inhibits Diaphyseal Fracture Healing in Mice by Alleviating Cartilage Formation

Norisoboldine (NOR), the major isoquinoline alkaloid constituent of a Chinese traditional medicine Radix Linderae, has been demonstrated to inhibit osteoclast differentiation and improve arthritis. The aim of this study is to examine the effect of NOR on bone fracture healing and the underlying mechanisms correlated with bone marrow stromal cells (BMSCs) differentiation to chondrocytes. Our results showed that NOR inhibits the tibia fracture healing process by suppressing cartilage formation, which leads to less endochondral ossification, indicated by less osterix and collage I signaling at the fracture site. Moreover, NOR significantly reduced the differentiation of primary BMSCs to chondrocytes in vitro by reducing the bone morphogenetic protein 2 (BMP2) signaling. These findings imply that NOR negatively regulates the healing of the tibial midshaft fracture, which might delay the union of the fractures and should be noticed when used in other treatments.

Mechanism of Wuyao-Ginseng Medicine Pair in the Prevention and Treatment of Diarrhea-Type Irritable Bowel Syndrome Based on Gene Expression Omnibus Chip Data

Based on a Gene Expression Omnibus (GEO) chip analysis combined with network pharmacology and molecular docking technology, in this study we explored the molecular targets and mechanism of the wuyao-ginseng medicine pair in the prevention and treatment of diarrhea-type irritable bowel syndrome (IBS-D). The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) was used to search for the chemical constituents and targets of wuyao and ginseng. The UniProt database was used to search for the target gene name. In the GEO database, IBS was searched to obtain GSE36701 and GSE14841 microarray data. We imported the intersection targets into the STRING database to construct a protein-protein interaction (PPI) network. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (Go) pathway analyses were performed using the Metascape database. A total of 30 active ingredients of wuyao-ginseng, 171 drug targets, 1257 IBS differentially expressed genes, and 20 drug-disease intersection genes were obtained from the GEO data. We screened the results and obtained the core active ingredients beta-sitosterol, DMPEC, Boldine, etc.; the core targets NCOA2, EGFR, VEGFA, etc.; and the key pathways P13K-Akt, MAPK, etc. The wuyao-ginseng medicine pair may be involved in inflammation-related signaling pathways, acting on disease targets such as NCOA2, EGFR, and VEGFA as well as pathways such as P13K-Akt and MAPK, thereby playing a key role in the prevention and treatment of IBS-D.

A review on the chemical constituents and pharmacological efficacies of Lindera aggregata (Sims) Kosterm

Lindera aggregata (Sims) Kosterm. (L. aggregata), which belongs to the genus Lindera in the family Lauraceae, is widely distributed in Asia and the temperate, tropical regions of North America. Its roots and leaves have been used for thousands of years as traditional Chinese medicine and/or functional food. To further explore its underlying nutritional value, this review provided a comprehensive insight into chemical constituents and pharmacological effects on L. aggregata. The phytochemical investigation of different parts of L. aggregata led to the identification of up to 349 components belonging to sesquiterpenoids, alkaloids, flavonoids, essential oils, and other compounds. Among them, sesquiterpenoids, flavonoids, and alkaloids are assessed as representative active ingredients of L. aggregata. A wide variety of pharmacological effects of L. aggregata, such as anti-hyperlipidemic, anti-tumor, anti-inflammatory, analgesic, and anti-oxidant, have been proved in vitro and in vivo. In summary, this review aims to provide a scientific basis and reference for further research and utilization of L. aggregata and lay the foundation for developing functional foods with potential active ingredients for the prevention and management of related diseases.

Natural medicines of targeted rheumatoid arthritis and its action mechanism

Rheumatoid arthritis (RA) is an autoimmune disease involving joints, with clinical manifestations of joint inflammation, bone damage and cartilage destruction, joint dysfunction and deformity, and extra-articular organ damage. As an important source of new drug molecules, natural medicines have many advantages, such as a wide range of biological effects and small toxic and side effects. They have become a hot spot for the vast number of researchers to study various diseases and develop therapeutic drugs. In recent years, the research of natural medicines in the treatment of RA has made remarkable achievements. These natural medicines mainly include flavonoids, polyphenols, alkaloids, glycosides and terpenes. Among them, resveratrol, icariin, epigallocatechin-3-gallate, ginsenoside, sinomenine, paeoniflorin, triptolide and paeoniflorin are star natural medicines for the treatment of RA. Its mechanism of treating RA mainly involves these aspects: anti-inflammation, anti-oxidation, immune regulation, pro-apoptosis, inhibition of angiogenesis, inhibition of osteoclastogenesis, inhibition of fibroblast-like synovial cell proliferation, migration and invasion. This review summarizes natural medicines with potential therapeutic effects on RA and briefly discusses their mechanisms of action against RA.

Discovery of natural anti-inflammatory alkaloids: Potential leads for the drug discovery for the treatment of inflammation

Inflammation is an adaptive response of the immune system to tissue malfunction or homeostatic imbalance. Corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) are frequently applied to treat varieties of inflammatory diseases but are associated with gastrointestinal, cardiovascular, and kidney side effects. Developing more effective and less toxic agents remain a challenge for pharmaceutical chemist due to the complexity of the different inflammatory processes. Alkaloids are widely distributed in plants with diverse anti-inflammatory activities, providing various potential lead compounds or candidates for the design and discovery of new anti-inflammatory drug candidates. Therefore, re-examining the anti-inflammatory alkaloid natural products is advisable, bringing more opportunities. In this review, we summarized and described the recent advances of natural alkaloids with anti-inflammatory activities and possible mechanisms in the period from 2009 to 2020. It is hoped that this review of anti-inflammatory alkaloids can provide new ideas for researchers engaged in the related fields and potential lead compounds for the discovery of anti-inflammatory drugs.

Biologically active isoquinoline alkaloids covering 2014-2018

Isoquinoline alkaloids, an important class of N-based heterocyclic compounds, have attracted considerable attention from researchers worldwide since the early 19th century. Over the past 200 years, many compounds from this class were isolated, and most of them and their analogs possess various bioactivities. In this review, we survey the updated literature on bioactive alkaloids and highlight research achievements of this alkaloid class during the period of 2014-2018. We reviewed over 400 molecules with a broad range of bioactivities, including antitumor, antidiabetic and its complications, antibacterial, antifungal, antiviral, antiparasitic, insecticidal, anti-inflammatory, antioxidant, neuroprotective, and other activities. This review should provide new indications or directions for the discovery of new and better drugs from the original naturally occurring isoquinoline alkaloids.

Herbal compounds for rheumatoid arthritis: Literatures review and cheminformatics prediction

Rheumatoid arthritis (RA) is a systemic disease characterized by autoimmunity, joint inflammation, and cartilage destruction, which affects 0.5-1% of the population. Many compounds from herbal medicines show the potentials to treat RA. On this basis, the compounds with good pharmacokinetic behaviors and drug-likeness properties will be further studied and developed. Therefore, the herbal compounds with anti-RA activities were reviewed in this paper, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 90 herbal compounds were analyzed, which were reported to be effective on RA models through anti-inflammation, chondroprotection, immunoregulation, antiangiogenesis, and antioxidation. Most of the herbal compounds have good drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-RA drug discovery.

Mechanistic studies on the absorption enhancement of a self-nanoemulsifying drug delivery system loaded with norisoboldine-phospholipid complex

Background

Norisoboldine (NOR), the main isoquinoline alkaloid constituent in Radix Linderae, was demonstrated to have an outstanding anti-arthritis activity. However, a poor oral bioavailability of NOR creates a barrier for its development and application.

Methods

A new self-nanoemulsifying drug delivery system (SNEDDS) loaded with the phospholipid complex (PC) was designed to improve the oral bioavailability of NOR. NOR-PC was prepared by solvent evaporation method with a mixture of phospholipid and NOR at a mass ratio of 3:1. The property of PC is to improve the liposolubility of NOR, and made PC embedded in the drug delivery system. The physicochemical property of NOR-PC was characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). According to the ability to dissolve NOR-PC, the oil and cosurfactant were chosen. The surfactant was selected based on its emulsification efficiency in SNEDDS. Pseudo-ternary phase diagram was created to select the best formulation of NOR-PC-SNEDDS, and the pharmacokinetic parameters were detected in rats. In addition, intestinal lymphatic transport and liver microsome experiment were studied to gain insight into the mechanism for NOR-PC-SNEDDS increasing the oral bioavailability of NOR.

Results

Solubility detection showed that the PC significantly improved the liposolubility of NOR. NOR-PC-SNEDDS was prepared using NOR-PC, Ethyl oleate, Labrasol, Cremophor EL and transcutol HP at a weight ratio of 1:2:3.36:2.24:2.4 (w/w/w/w/w). The particle size and zeta potential of NOR-PC-SNEDDS were 36.72±1.47 nm and -4.91±0.49 mV after dilution with distilled water at a ratio of 1:50 (w/w). The absolute bioavailability of NOR in the NOR-PC-SNEDDS group significantly increased and the value was 372% in relative to NOR group. Further studies indicated that NOR-PC-SNEDDS promoted the oral bioavailability of NOR by enhancing intestinal lymphatic absorption and inhibiting Phase II metabolism of NOR.

Conclusion

These findings suggested that NOR-PC-SNEDDS was able to promote the oral bioavailability of NOR, which provided a foundation for the further development and application of NOR.

Preparation and characterization of general-purpose gelatin-based co-loading flavonoids nano-core structure

Flavonoids (FLAs) possess anti-cancer, anti-viral, anti-bacterial, and anti-oxidant properties. In this study, gelatin nanoparticles (GNPs) with controllable surface potential and diameter was prepared through a modified two-step desolvation. Two well-known flavonoids, namely, low-molecular weight Genistein (GEN) and high-molecular weight Icariin (ICA), were adsorbed onto the surface of GNPs (FLA@GNPs). The characteristics of GNPs and the main parameters affecting flavonoid adsorption were studied to evaluate the adsorption capacity and structural stability of FLA@GNPs. Furthermore, co-adsorption of GEN and ICA was detected. The adsorption mechanism of GNPs with FLA was further discussed. Results showed that the low-molecular weight GEN could be effectively adsorbed by GNPs, and their entrapment efficiencies were over 90% under optimized conditions. The total drug loading of the co-adsorbed FLA@GNPs was significantly higher than that of the single drug loaded (GEN or ICA). GEN@GNPs could maintain its structural stability under acidic conditions (pH = 2) at room temperature (25 °C). This protective function enables both ICA and GEN to be bioactive at room temperature for at least 180 days. The characteristics of GNPs adsorption indicate that the hydrogen bonding theory of the combination of gelatin molecules with polyphenols cannot sufficiently explain the binding of GNPs with polyphenols. FLA@GNPs is a promising general-purpose gelatin-based co-loading preload structure with simplified operation and storage condition.

The absorption enhancement of norisoboldine in the duodenum of adjuvant-induced arthritis rats involves the impairment of P-glycoprotein

Lindera aggregata (Sims) Kosterm root has been used in traditional Chinese medicine for the treatment of rheumatism palsy, dyspepsia and frequent urination for a long time. Norisoboldine, the main active constituent of this herb drug, possesses outstanding anti-arthritis activity. However, the in vivo disposition of norisoboldine is known to a limited extent, especially under the pathological condition of rheumatoid arthritis (RA). The aim of this study is to investigate whether and how the absorption of norisoboldine is altered in adjuvant-induced arthritis (AIA) rats. Comparative studies of the intestinal absorption of norisoboldine in normal and AIA rats at different pathological stages of the arthritis were performed using in situ single-pass intestinal perfusion, and the effects of an inhibitor of efflux proteins were also investigated. Norisoboldine was shown to be a substrate of P-glycoprotein (P-gp), as P-gp inhibitor verapamil markedly increased the permeability coefficient (P_eff ) of norisoboldine by 88% in the intestine of normal rats. Compared with normal rats, AIA rats displayed increased P_eff values of norisoboldine by 84% and 86% on day 5 and day 10 after the appearance of the secondary response of arthritis, respectively. Verapamil could eliminate the difference of intestinal absorption of norisoboldine between normal and AIA rats. Further studies showed that impaired expression and activity of P-gp in AIA rats play a decisive role in the absorption enhancement of norisoboldine. Notably, the impairment of P-gp function positively correlated with the severity of arthritis. Copyright © 2016 John Wiley & Sons, Ltd.

Plants and their active compounds: natural molecules to target angiogenesis

Angiogenesis, or new blood vessel formation, is an important process in the pathogenesis of several diseases and thus has been targeted for the prevention and treatment for many disorders. However, the anti-angiogenic agents that are currently in use are mainly synthetic compounds and humanized monoclonal antibodies, which are either expensive or toxic, thereby limiting their use in many patients. Therefore, it is necessary to identify less toxic, inexpensive, novel and effective anti-angiogenic molecules. Several studies have indicated that natural plant products can meet these criteria. In this review, we discuss the anti-angiogenic properties of natural compounds isolated from plants and the molecular mechanisms by which these molecules act. Finally, we summarize the advantages of using plant products as anti-angiogenic agents. Compared with currently available anti-angiogenic drugs, plant products may not only have similar therapeutic potential but are also inexpensive, less toxic, and easy to administer. However, novel and effective strategies are necessary to improve their bioavailability for clinical use.

The treatment of rheumatoid arthritis using Chinese medicinal plants: From pharmacology to potential molecular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a common worldwide public health problem. Traditional Chinese Medicine (TCM) achieved some results to some extent in the treatment of rheumatoid arthritis (RA). Especially in China, TCM formulas are used in the clinic because of their advantages. Some of these TCM formulas have been used for thousands of years in ancient China, they pays much attention to strengthening healthy qi, cleaning heat, and wet, activating blood, etc. So TCM in anti-RA drug is considered as a simple and effective method. In addition, TCM are also traditionally used as extracts and many Chinese herbs which are considered to be effective for RA. With the advancement of technologies and research methods, researchers have devoted themselves to exploring new therapeutic materials from troves of TCM. The components of TCM are identified and purified, which include alkaloids, coumarins, flavonoids, saponins and so on. However, little or no review works are found in the research literature on the anti-RA drugs from TCM. The present review aims to provide systematically reorganized information on the ethnopharmacology, phytochemistry and pharmacology of TCM used traditionally against RA. The information recorded in this review will provide new directions for researchers in the future.

MATERIALS AND METHODS

Relevant scientific literatures were collected from Chinese traditional books and Chinese Pharmacopoeia. Several important pharmacology data, clinical observations, animal experiments on effects of anti-RA drugs from TCM and their mechanisms were extracted from a library and electric search (Pubmed, PubChem Compound, Science Direct, Spring Link, Elsevier, Web of Science, CNKI, Wan Fang, Bai du, The Plant List, etc.). We collected information published between 2002 and 2015 on Chinese medicine in the treatment of RA. Information was also acquired from local classic herbal literature, conference papers, government reports, and PhD and MSc dissertations.

RESULTS

This review mainly introduces the current research on anti-RA TCM formulas, extracts and compounds from TCM, pharmacological data and potential mechanisms (inhibit osteoclast proliferation, suppress fibroblast-like synoviocytes (FLSs) growth, decrease the expression of inflammatory cytokines, blocking signal pathways, etc.).

CONCLUSIONS

TCM, as a multi-component and multi-target approach, which is a perfect match with the holistic concept of systems biology, is applicable in the treatment of RA. The synergistic connections of Chinese herbs and mechanisms of related active compounds on RA increase the trust for TCM. TCM as alternative remedies for RA not only has an important position in the world market, but also has an irreplaceable role in the treatment of RA in future.

Pristimerin inhibits angiogenesis in adjuvant-induced arthritic rats by suppressing VEGFR2 signaling pathways

Rheumatoid arthritis (RA) is a progressive, inflammatory autoimmune disease. As RA progresses, the hyperplastic synovial pannus creates a hypoxic, inflammatory environment that induces angiogenesis. Further vascularization of the synovial tissue promotes pannus growth and continued infiltration of inflammatory leukocytes, thus perpetuating the disease. Pristimerin inhibits inflammation and tumor angiogenesis. The present study focused on the inhibition of angiogenesis by Pristimerin in adjuvant-induced arthritic rats and the underlying molecular mechanisms. Our results clearly demonstrate for the first time that Pristimerin significantly reduces vessel density in synovial membrane tissues of inflamed joints and reduces the expression of pro-angiogenic factors in sera, including TNF-α, Ang-1, and MMP-9. Pristimerin also decreased the expression of VEGF and p-VEGFR2 in the synovial membrane, whereas the total amount of VEGFR2 remained unchanged. Pristimerin suppressed the sprouting vessels of the aortic ring and inhibited VEGF-induced HFLS-RA migration in vitro. Pristimerin also inhibited VEGF-induced proliferation, migration and tube formation by HUVECs, blocked the autophosphorylation of VEGF-induced VEGFR2 and consequently downregulated the signaling pathways of activated PI3K, AKT, mTOR, ERK1/2, JNK, and p38 in VEGF-induced HUVECs. Our results indicate that Pristimerin suppressed synovial angiogenesis in our rat model and in vitro by interrupting the targeting of VEGFR2 activation. Therefore, Pristimerin has potential as an angiogenesis inhibitor in the treatment of rheumatoid arthritis.

Genistein exerts growth inhibition on human osteosarcoma MG-63 cells via PPARγ pathway

The peroxisome proliferator-activated receptor γ (PPARγ) is emerging as an important regulator in various metabolic processes of cancer. Genistein, as a major isoflavonoid isolated from dietary soybean, possesses a wide variety of biological activities, particularly, in cancer prevention. However, the mechanisms by which genistein elicits its growth inhibiting effects in osteosarcoma (OS) MG-63 cells have not been extensively elucidated. MG-63 cells were treated for 2 days with various concentrations of genistein and/or GW9662 (a selective antagonist of PPARγ). The effect of different drugs on cell viability was determined by Cell Counting Kit-8 (CCK-8). The assay of cell proliferation was performed using 5-ethynyl-2'-deoxyuridine (EdU). The changes of apoptosis and cell cycle progression were detected by flow cytometry experiments. The protein expression of PPARγ pathway (PPARγ, PTEN, BCL-2, Survivin, P21WAF1/CIP1 and Cyclin B1) was determined by western blot analysis. The expression of PPARγ and PTEN mRNA was detected by real-time quantitative RT-PCR analysis. We report that genistein caused OS cell growth inhibition. We found that the PPARγ expression in OS cells increased after genistein treatment. Further studies on the mechanisms of genistein revealed a series of cell growth changes related to the PPARγ pathway; while cell cycle changes can be reversed by GW9662. Genistein plays an important role in preventing OS cell growth, which can impede the OS cell cycle as a non-toxic activator of PPARγ, providing novel insights into the mechanisms of the therapeutic activities of genistein.

Norisoboldine ameliorates collagen-induced arthritis through regulating the balance between Th17 and regulatory T cells in gut-associated lymphoid tissues

Norisoboldine (NOR), the main active ingredient of the dry root of Lindera aggregata, was previously proven to have substantial therapeutic effects on collagen-induced arthritis (CIA) in mice by oral administration. However, it exhibited a very poor bioavailability in normal rats. The pharmacokinetic-pharmacodynamics disconnection attracts us to explore its anti-arthritic mechanism in more detail. In this study, NOR, administered orally, markedly attenuated the pathological changes in CIA rats, which was accompanied by the down-regulation of pro-inflammatory cytokines and the up-regulation of anti-inflammatory cytokine IL-10. Pharmacokinetic studies demonstrated that the plasma concentration of NOR was moderately elevated in CIA rats compared with normal rats, but it was still far lower than the minimal effective concentration required for inhibiting the proliferation and activation of T lymphocytes in vitro. Interestingly, NOR was shown to regulate the balance between Th17 and regulatory T (Treg) cells in the intestinal lymph nodes more strikingly than in other tissues. It could increase the expression of Foxp3 mRNA in both gut and joints, and markedly up-regulate the number of integrin α4β7 (a marker of gut source)-positive Foxp3(+) cells in the joints of CIA rats. These results suggest that the gut might be the primary action site of NOR, and NOR exerts anti-arthritis effect through regulating the balance between Th17 and Treg cells in intestinal lymph nodes and yielding a trafficking of lymphocytes (especially Treg cells) from the gut to joint. The findings of the present study also provide a plausible explanation for the anti-arthritic effects of poorly absorbed compounds like NOR.

Scopoletin suppresses IL-6 production from fibroblast-like synoviocytes of adjuvant arthritis rats induced by IL-1β stimulation

Scopoletin, a coumarin compound naturally occurring in many medicinal plants, has previously been demonstrated to ameliorate synovial inflammation and destruction of cartilage and bone in adjuvant arthritis (AA) rats. As interleukin (IL)-6 is critically involved in the initiation and development of rheumatoid arthritis (RA), the present study was performed to investigate the effect of scopoletin on IL-6 production from fibroblast-like synoviocytes (FLS) to get insight into its anti-RA mechanisms. FLS were isolated from synovial membrane tissues of AA rats, and stimulated with IL-1β (10 ng/mL). Scopoletin, at concentrations of 15, 30, and 60 μM, was shown to only moderately inhibit FLS proliferation, but dramatically reduce IL-6 production at both mRNA and protein levels. It also inhibited the phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), protein kinase C (PKC) and cAMP response element binding protein (CREB). These findings suggest that scopoletin exerts anti-RA action probably through suppressing IL-6 production from FLS via MAPK/PKC/CREB pathways.

Role of cathepsin B in regulating migration and invasion of fibroblast-like synoviocytes into inflamed tissue from patients with rheumatoid arthritis

Cathepsin B (CB), an important proteinase that participates in joint destruction in rheumatoid arthritis (RA), exhibits higher expression in fibroblast-like synoviocyte (FLS) of abnormal proliferative synovial tissues. Whether and how it affects the biological behaviours of RA-FLS, such as migration and invasion, are poorly understood. In the present study, CB expression in synovial tissues of patients with RA and ostearthritis (OA) were measured by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC), respectively. Stable depletion of endogenous CB was achieved by small interfering RNA (siRNA) transfection, and decrease of CB activity was acquired by using its specific inhibitor (CA074Me). The effects of CA074Me and RNA interference (RNAi) treatments on proliferation, migration, invasion, matrix metalloproteinase (MMP)-2/-9 expression, focal adhesion kinase (FAK) activation, and mitogen-activated protein kinases (MAPKs) phosphorylation of FLS were analysed. In RA synovial tissues, CB was expressed at elevated levels compared with OA synovial tissues. CA074Me could inhibit invasion of FLS obtained from RA patients in an ex-vivo invasion model. CA074Me and siRNA treatments suppressed the migration and invasion of FLS, reduced the activity, expression and mRNA level of MMP-2, restrained the activation of FAK and reduced the expression of F-actin. Moreover, CA074Me decreased the phosphorylation of P38 MAPK and c-Jun N-terminal kinase (JNK) in FLS, while siCB treatment reduced the phosphorylation of P38 but not JNK. CB substantially contributes to the invasive phenotype of FLS that leads to joint destruction in RA. This proteinase may show promise as a therapeutic target in inflammatory arthritis.

The potential role of angiogenic factors in rheumatoid arthritis

Angiogenesis is an important phenomenon in the pathogenesis of some diseases, such as numerous types of tumors and autoimmunity, and also a number of soluble and cell-bound factors may stimulate neovascularization in inflammatory reaction processes. Here, by highlighting the significance of angiogenesis reaction in rheumatoid arthritis (RA), we will mainly focus on the role of various growth factors, cytokines, enzymes, cells, hypoxic conditions and transcription factors in the angiogenic process and we will then explain some therapeutic strategies based on blockage of angiogenesis and modification of the vascular pathology in RA.

Norisoboldine suppresses VEGF-induced endothelial cell migration via the cAMP-PKA-NF-κB/Notch1 pathway

The migration of endothelial cells has been regarded as a potential target for the treatment of angiogenesis-related diseases. Previously, we demonstrated that norisoboldine (NOR), an alkaloid compound isolated from Radix Linderae, can significantly suppress synovial angiogenesis by selectively inhibiting endothelial cell migration. In this study, we evaluated the importance of various pathways in VEGF-induced endothelial cell migration using specific inhibitor. VEGF-induced endothelial cell migration and sprouting were significantly inhibited by H-89 (an inhibitor of protein kinase A (PKA)) but not by inhibitors of other pathways. NOR markedly suppressed VEGF-induced intracytoplasmic cAMP production and PKA activation and thereby down-regulated the activation of downstream components of the PKA pathway, including enzymes (src, VASP and eNOS) and the transcription factor NF-κB. Moreover, the transcription activation potential of NF-κB, which is related to IκBα phosphorylation and the disruption of the p65/IκBα complex, was reduced by NOR. Meanwhile, NOR selectively inhibited the expression of p-p65 (ser276) but not p-p65 (ser536) or PKAc, indicating that PKAc participates in the regulation of NF-κB by NOR. Co-immunoprecipitation and immunofluorescence assays confirmed that NOR inhibited the formation of the PKAc/p65 complex and thereby decreased p65 (ser276) phosphorylation to prevent p65 binding to DNA. Docking models indicated that the affinity of NOR for PKA was higher than that of the original PKA ligand. Moreover, the fact that H-89 improved Notch1 activation, but DAPT (an inhibitor of Notch) failed to affect PKA activation, suggested that PKA may act on upstream of Notch1. In conclusion, the inhibitory effects of NOR on endothelial cell migration can be attributed to its modulation of the PKA pathway, especially on the processes of p65/IκBα complex disruption and PKAc/p65 complex formation. These results suggest that NOR inhibit VEGF-induced endothelial cell migration via a cAMP-PKA-NF-κB/Notch1 signaling pathway.