Norisoboldine

Norisoboldine ameliorates collagen-induced arthritis through regulating the balance between Th17 and regulatory T cells in gut-associated lymphoid tissues.[Pubmed:25481498]

Toxicol Appl Pharmacol. 2015 Jan 1;282(1):90-9.

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 alpha4beta7 (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.

Norisoboldine attenuates inflammatory pain via the adenosine A1 receptor.[Pubmed:24395183]

Eur J Pain. 2014 Aug;18(7):939-48.

BACKGROUND: Norisoboldine (NOR) is a benzylisoquinoline alkaloid isolated from Radix Linderae, a traditional Chinese medicine. Our previous studies have demonstrated that it produces anti-inflammatory and anti-rheumatoid arthritis effects. METHODS: The present study was undertaken to explore the analgesic effects of NOR and its potential mechanism in the formalin test and the acetic acid writhing test. RESULTS: Oral administration of NOR dose dependently attenuated the formalin-induced pain responses in the second phase, and reduced formalin-induced paw oedema. It also diminished acetic acid-induced writhing responses but had no effect on acute thermal pain in the hotplate test. The mechanistic studies suggested that the adenosine system, but not the opioid receptor system, is involved in NOR-induced antinociception. Naloxone, a non-selective opioid receptor antagonist, had no effect on NOR-induced analgesic action. However, caffeine (a non-selective adenosine receptor antagonist) completely reversed the analgesic effect of NOR in formalin-induced nociceptive responses in the second phase, and 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX, a selective adenosine A1 receptor antagonist) completely inhibited NOR-induced analgesia in both formalin-induced nociceptive responses and acetic acid-induced writhing responses. In addition, NOR reduced formalin-induced activation of extracellular signal-regulated kinase and calcium/calmodulin-dependent protein kinase II in the spinal cord, which is also blocked by DPCPX. Furthermore, NOR decreased forskolin-evoked cyclic adenosine monophosphate levels in mouse spinal cord neuronal cultures through the adenosine A1 receptor. CONCLUSION: Our data demonstrate that NOR produces the analgesic effect in inflammatory pain by a mechanism related to the adenosine system.

Norisoboldine inhibits the production of pro-inflammatory cytokines in lipopolysaccharide-stimulated RAW 264.7 cells by down-regulating the activation of MAPKs but not NF-kappaB.[Pubmed:20352482]

Inflammation. 2010 Dec;33(6):389-97.

Norisoboldine is the main isoquinoline alkaloid occurring in Radix Linderae, the dry roots of Lindera aggregata (Lauraceae family). It has been previously implicated to be able to ameliorate the synovial inflammation and abnormal immune conditions in collagen-induced arthritis of mice. To get insight to the potential anti-inflammatory mechanisms of this alkaloid compound, the present study was undertaken to explore the effects of Norisoboldine on the production of pro-inflammatory cytokines from macrophages stimulated by lipopolysaccharide. In vitro, Norisoboldine substantially reduced the production of nitric oxide (NO), tumor necrosis factor (TNF)-alpha as well as interleukin (IL)-1beta from RAW264.7 macrophage cells in a concentration-dependent manner, whereas it only slightly reduced the production of interleukin-6 (IL-6) at both protein and transcription levels. Of note, the preventive effects of Norisoboldine on the release of pro-inflammatory cytokines were correlated with the inhibitory action on the phosphorylations of mitogen-activated protein (MAP) kinases including p38, extracellular signal-regulated kinase (ERK) and c-jun NH(2)-terminal kinase (JNK), but not on the activation and translocation of nuclear factor-kappaB (NF-kappaB). It can be therefore concluded that Norisoboldine inhibits the macrophage activation and the resultant production of pro-inflammatory cytokines via down-regulating the activation of MAPKs signaling pathways rather than NF-kappaB.

Norisoboldine induces apoptosis of fibroblast-like synoviocytes from adjuvant-induced arthritis rats.[Pubmed:24613208]

Int Immunopharmacol. 2014 May;20(1):110-6.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by pronounced synovial inflammation and hyperplasia, in which there may be an imbalance between the growth and death of fibroblast-like synoviocytes (FLS). Norisoboldine (NOR), the main active constituent in the alkaloid fraction isolated from Radix Linderae, was previously demonstrated to alleviate arthritis severity in experimental RA. This study aimed to evaluate the effects of NOR on proliferation and apoptosis of FLS from adjuvant-induced arthritis (AIA) rats to elucidate the mechanism of its inhibitory effect on inflammatory synovial hyperplasia in RA. Our results indicated that NOR exhibited a pro-apoptotic effect on AIA FLS but only slightly affected cell proliferation and the cell cycle. Following treatment with NOR for 24h, the activation of caspase 3 and caspase 9 and the cleavage of poly (ADP-ribose) polymerase (PARP) in AIA FLS were observed; however, caspase 8 remained unaffected. Meanwhile, a flow cytometric assay revealed that NOR significantly increased the percentage of apoptotic cells, causing the loss of the depolarized mitochondrial membrane potential and the release of cytochrome C. The expression of Bax and Bcl-2 was also regulated by NOR treatment. Additionally, the expression of p53 protein was up-regulated by NOR, and pretreatment with PFT-alpha, a p53 specific inhibitor, reversed the increase in FLS apoptosis caused by NOR. These findings indicated that NOR-induced apoptosis in AIA FLS is achieved via a mitochondrial-dependent pathway, which may be mediated by promoting the release of cytochrome C and by regulating the expression of Bax and Bcl-2 proteins, and p53 might also be required for NOR-induced apoptosis in AIA FLS.

Norisoboldine alleviates joint destruction in rats with adjuvant-induced arthritis by reducing RANKL, IL-6, PGE(2), and MMP-13 expression.[Pubmed:23396374]

Acta Pharmacol Sin. 2013 Mar;34(3):403-13.

AIM: To explore the effects of Norisoboldine (NOR), a major isoquinoline alkaloid in Radix Linderae, on joint destruction in rats with adjuvant-induced arthritis (AIA) and its underlying mechanisms. METHODS: AIA was induced in adult male SD rats by intradermal injection of Mycobacterium butyricum in Freund's complete adjuvant at the base of the right hind paw and tail. From d 14 after immunization, the rats were orally given NOR (7.5, 15, or 30 mg/kg) or dexamethasone (0.5 mg/kg) daily for 10 consecutive days. Joint destruction was evaluated with radiological scanning and H&E staining. Fibroblast-like synoviocytes (FLS) were prepared from fresh synovial tissues in the AIA rats. The expression of related proteins and mRNAs were detected by ELISA, Western blotting and RT-PCR. RESULTS: In AIA rats, NOR (15 and 30 mg/kg) significantly decreased the swelling of paws and arthritis index scores, and elevated the mean body weight. NOR (30 mg/kg) prevented both the infiltration of inflammatory cells and destruction of bone and cartilage in joints. However, NOR (15 mg/kg) only suppressed the destruction of bone and cartilage, but did not obviously ameliorate synovial inflammation. NOR (15 and 30 mg/kg) significantly decreased the serum levels of receptor activator of nuclear factor kappaB ligand (RANKL), IL-6, PGE2, and MMP-13, but not the osteoprotegerin and MMP-1 levels. The mRNA levels of RANKL, IL-6, COX-2, and MMP-13 in synovium were also suppressed. Dexamethasone produced similar effects in AIA rats as NOR did, but without elevating the mean body weight. In the cultured FLS, treatment with NOR (10 and 30 mmol/L) significantly decreased the secretion of RANKL, IL-6, PGE2, and MMP-13 proteins. Furthermore, the treatment selectively prevented the activation of MAPKs, AKT and transcription factor AP-1 component c-Jun, but not the recruitment of TRAF6 or the activation of JAK2/STAT3. Treatment of the cultured FLS with the specific inhibitors of p38, ERK, AKT, and AP-1 significantly decreased the secretion of RANKL, IL-6, PGE2, and MMP-13 proteins. CONCLUSION: NOR can alleviate joint destruction in AIA rats by reducing RANKL, IL-6, PGE2, and MMP-13 expression via the p38/ERK/AKT/AP-1 pathway.

Norisoboldine suppresses VEGF-induced endothelial cell migration via the cAMP-PKA-NF-kappaB/Notch1 pathway.[Pubmed:24349042]

PLoS One. 2013 Dec 9;8(12):e81220.

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-kappaB. Moreover, the transcription activation potential of NF-kappaB, which is related to IkappaBalpha phosphorylation and the disruption of the p65/IkappaBalpha 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-kappaB 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/IkappaBalpha complex disruption and PKAc/p65 complex formation. These results suggest that NOR inhibit VEGF-induced endothelial cell migration via a cAMP-PKA-NF-kappaB/Notch1 signaling pathway.