Hai-Ning Lv

Anti-Neuroinflammatory Effect of MC13, a Novel Coumarin Compound From Condiment Murraya, Through Inhibiting Lipopolysaccharide-Induced TRAF6-TAK1-NF-κB, P38/ERK MAPKS and Jak2-Stat1/Stat3 Pathways.

MC13 is a novel coumarin compound found in Murraya, an economic crop whose leaves are widely used as condiment (curry) in cuisine. The aims of the present study were to investigate the neuroprotective effects of MC13 on microglia‐mediated inflammatory injury model as well as potential molecular mechanism. Cell viability and apoptosis assay demonstrated that MC13 was not toxic to neurons and significantly protected neurons from microglia‐mediated inflammatory injury upon lipopolysaccharide (LPS) stimulation. Results showed that MC13 markedly inhibited LPS‐induced production of various inflammatory mediators, including nitrite oxide (Griess method), TNF‐α and IL‐6 (ELISA assay) in a concentration‐dependent manner. Mechanism study showed that MC13 could suppress the activation of NF‐κB, which was the central regulator for inflammatory response, and also decreased the interaction of TGF‐β‐activated kinase 1 (TAK1)‐binding protein (TAB2) with TAK1 and TNF receptor associated factor (TRAF6), leading to the decreased phosphorylation levels of NF‐κB upstream regulators such as IκB and IκB kinase (IKK). MC13 also significantly down‐regulated the phosphorylation levels of ERK and p38 MAPKs, which played key roles in microglia‐mediated inflammatory response. Furthermore, MC13 inhibited Jak2‐dependent Stat1/3 signaling pathway activation by blocking Jak2 phosphorylation, Stat1/3 phosphorylation, and nuclear translocation. Taken together, our results demonstrated that MC13 protected neurons from microglia‐mediated neuroinflammatory injury by inhibiting TRAF6‐TAK1‐NF‐κB, p38/ERK MAPKs, and Jak2‐Stat1/3 pathways. Finally, MC13 might interact with LPS and interfere LPS‐binding to cell membrane surface. These findings suggested that coumarin might act as a potential medicinal agent for treating neuroinflammation as well as inflammation‐related neurodegenerative diseases. J. Cell. Biochem. 116: 1286–1299, 2015.

Natural small molecule FMHM inhibits lipopolysaccharide-induced inflammatory response by promoting TRAF6 degradation via K48-linked polyubiquitination.

TNF receptor-associated factor 6 (TRAF6) is a key hub protein involved in Toll-like receptor-dependent inflammatory signaling pathway, and it recruits additional proteins to form multiprotein complexes capable of activating downstream NF-κB inflammatory signaling pathway. Ubiquitin-proteasome system (UPS) plays a crucial role in various protein degradations, such as TRAF6, leading to inhibitory effects on inflammatory response and immunologic function. However, whether ubiquitination-dependent TRAF6 degradation can be used as a novel anti-inflammatory drug target still remains to be explored. FMHM, a bioactive natural small molecule compound extracted from Chinese herbal medicine Radix Polygalae, suppressed acute inflammatory response by targeting ubiquitin protein and inducing UPS-dependent TRAF6 degradation mechanism. It was found that FMHM targeted ubiquitin protein via Lys48 site directly induced Lys48 residue-linked polyubiquitination. This promoted Lys48 residue-linked polyubiquitin chain formation on TRAF6, resulting in increased TRAF6 degradation via UPS and inactivation of downstream NF-κB inflammatory pathway. Consequently, FMHM down-regulated inflammatory mediator levels in circulation, protected multiple organs against inflammatory injury in vivo, and prolong the survival of endotoxemia mouse models. Therefore, FMHM can serve as a novel lead compound for the development of TRAF6 scavenging agent via ubiquitination-dependent mode, which represents a promising strategy for treating inflammatory diseases.

Benzocoumarins: Isolation, Synthesis, and Biological Activities

Benzocoumarins are coumarins with a phenyl group bonded to 3,4-, 5,6-, 6,7-, or 7,8-positions. Over the past years, significant efforts have been made not only to isolate the novel structural analogs of benzocoumarins with prominent bioactivities but also to design new synthetic methods to synthesize benzocoumarins with better or novel biological properties. The aim of this review is to provide the readers with an overview of the research progress of benzocoumarins from 1953 to May 2014, covering its isolation, synthesis, and biological activities.

Rhodomollins A and B, two Diterpenoids with an Unprecedented Backbone from the Fruits of Rhododendron molle

Two new grayanoids, rhodomollin A (1) and rhodomollin B (2), possessing an unprecedented D-homo grayanane carbon skeleton, were isolated from the fruits of Rhododendron molle. The structures of 1 and 2 were fully characterized using a combination of spectroscopic analyses and X-ray crystallography. Rhodomollin B (2) exhibited modest activity against influenza virus A/95-359, with an IC50 value of 19.24 μM.

Highly selective inhibition of IMPDH2 provides the basis of antineuroinflammation therapy

Significance Inosine monophosphate dehydrogenase (IMPDH) is an attractive target for immunosuppressive agents. Currently, small-molecule inhibitors do not show good selectivity for different IMPDH isoforms (IMPDH1 and IMPDH2), resulting in some adverse effects, which limit their use. Here, we identified Cys140 as an isoform-selective druggable binding site for IMPDH2 inhibition but not for IMPDH1. We found small-molecule sappanone A directly covalently targets Cys140 in IMPDH2 to block its activity, resulting in neuroinflammatory inhibition with less side effects than pan-IMPDH inhibitor. In summary, our findings reveal Cys140 is a druggable binding site for selectively inhibiting IMPDH2 for neuroinflammatory diseases with less unfavorable tolerability profile. Inosine monophosphate dehydrogenase (IMPDH) of human is an attractive target for immunosuppressive agents. Currently, small-molecule inhibitors do not show good selectivity for different IMPDH isoforms (IMPDH1 and IMPDH2), resulting in some adverse effects, which limit their use. Herein, we used a small-molecule probe specifically targeting IMPDH2 and identified Cysteine residue 140 (Cys140) as a selective druggable site. On covalently binding to Cys140, the probe exerts an allosteric regulation to block the catalytic pocket of IMPDH2 and further induces IMPDH2 inactivation, leading to an effective suppression of neuroinflammatory responses. However, the probe does not covalently bind to IMPDH1. Taken together, our study shows Cys140 as a druggable site for selectively inhibiting IMPDH2, which provides great potential for development of therapy agents for autoimmune and neuroinflammatory diseases with less unfavorable tolerability profile.

Selective Activation of Nociceptor TRPV1 Channel and Reversal of Inflammatory Pain in Mice by a Novel Coumarin Derivative Muralatin L from Murraya alata

Coumarin and its derivatives are fragrant natural compounds isolated from the genus Murraya that are flowering plants widely distributed in East Asia, Australia, and the Pacific Islands. Murraya plants have been widely used as medicinal herbs for relief of pain, such as headache, rheumatic pain, toothache, and snake bites. However, little is known about their analgesic components and the molecular mechanism underlying pain relief. Here, we report the bioassay-guided fractionation and identification of a novel coumarin derivative, named muralatin L, that can specifically activate the nociceptor transient receptor potential vanilloid 1 (TRPV1) channel and reverse the inflammatory pain in mice through channel desensitization. Muralatin L was identified from the active extract of Murraya alata against TRPV1 transiently expressed in HEK-293T cells in fluorescent calcium FlexStation assay. Activation of TRPV1 current by muralatin L and its selectivity were further confirmed by whole-cell patch clamp recordings of TRPV1-expressing HEK-293T cells and dorsal root ganglion neurons isolated from mice. Furthermore, muralatin L could reverse inflammatory pain induced by formalin and acetic acid in mice but not in TRPV1 knock-out mice. Taken together, our findings show that muralatin L specifically activates TRPV1 and reverses inflammatory pain, thus highlighting the potential of coumarin derivatives from Murraya plants for pharmaceutical and medicinal applications such as pain therapy.

Caruifolin D from artemisia absinthium L. inhibits neuroinflammation via reactive oxygen species-dependent c-jun N-terminal kinase and protein kinase c/NF-κB signaling pathways.

This work aims to evaluate the anti-neuroinflammatory effects of natural sesquiterpene dimer caruifolin D from Artemisia absinthium L., which is an edible vegetable or traditional medicinal food in East Asia due to its sedation, anti-asthma and antipruritic effects. In this study, we reported that caruifolin D significantly inhibited the productions of various neuroinflammatory mediators from microglia in response to bacterial lipopolysaccharide stimulation. Moreover, anti-inflammatory mechanism study showed that caruifolin D markedly suppressed the production of intracellular reactive oxygen species, which was an important player involved in neuroinflammation, leading to inhibitory effects on the activations of protein kinase C (PKC) and c-Jun N-terminal kinase (JNK), which were two major neuroinflammatory signaling pathways in the brains. Furthermore, caruifolin D protected neurons against microglia-mediated neuronal inflammatory damages by up-regulating neuronal viability and maintaining healthy neuronal morphology. Taken together, these results expanded our knowledge about the anti-neuroinflammatory and neuroprotective mechanism of Artemisia absinthium L., and also suggested that caruifolin D was a major anti-inflammatory component from Artemisia absinthium L., which might be developed as a drug candidate for neuroinflammation-related diseases.

Oleanane-type triterpene saponins and cassaine-type diterpenoids from Erythrophleum fordii.

Phytochemical investigation of the EtOH extract of the leaves of Erythrophleum fordii led to the isolation of two oleanane-type triterpene saponins (1-2) and five cassaine-type diterpenoids (4-8) along with one known methyl 3 β-hydroxy-erythrosuamate (3). Their structures were established by extensive NMR, as well as ESI-MS analyses and acid hydrolysis. Biological evaluation of compounds 3- 8 against five human cancer cell lines revealed that compounds 5-7 exhibited potent cytotoxic activity with IC₅₀ values ranging from 1.51 to 8.68 µM.

Pyrrolo[2,1-a]isoquinoline and pyrrole alkaloids from Sinomenium acutum

Abstract Two pyrrolo[2,1-a]isoquinolines (1 and 2) and three pyrrole alkaloids (3−5), including three new ones, named sinopyrines A−C (1−3), were isolated from the 95% EtOH extract of the stems and rhizomes of Sinomenium acutum (Thumb.) Rehd. et Wils. The structures of the new compounds were elucidated on the basis of spectroscopic data. This is the first report of pyrrole-bearing natural compounds from the family Menispermaceae.

Highly Selective Activation of Heat Shock Protein 70 by Allosteric Regulation Provides an Insight into Efficient Neuroinflammation Inhibition.

Heat shock protein 70 (Hsp70) is widely involved in immune disorders, making it as an attractive drug target for inflammation diseases. Nonselective induction of Hsp70 upregulation for inflammation therapy could cause extensive interference in inflammation-unrelated protein functions, potentially resulting in side effects. Nevertheless, direct pharmacological activation of Hsp70 via targeting specific functional amino acid residue may provide an insight into precise Hsp70 function regulation and a more satisfactory treatment effect for inflammation, which has not been extensively focused. Here we show a cysteine residue (Cys306) for selective Hsp70 activation using natural small-molecule handelin. Covalent modification of Cys306 significantly elevates Hsp70 activity and shows more satisfactory anti-neuroinflammation effects. Mechanism study reveals Cys306 modification by handelin induces an allosteric regulation to facilitate adenosine triphosphate hydrolysis capacity of Hsp70, which leads to the effective blockage of subsequent inflammation signaling pathway. Collectively, our study offers some insights into direct pharmacological activation of Hsp70 by specially targeting functional cysteine residue, thus providing a powerful tool for accurately modulating neuroinflammation pathogenesis in human with fewer undesirable adverse effects.