The therapeutic effects of daphnetin in collagen-induced arthritis involve its regulation of Th17 cells

The molecular effects underlying the pharmacological activities of daphnetin

As an increasingly well-known derivative of coumarin, daphnetin (7,8-dithydroxycoumarin) has demonstrated various pharmacological activities, including anti-inflammation, anti-cancer, anti-autoimmune diseases, antibacterial, organ protection, and neuroprotection properties. Various studies have been conducted to explore the action mechanisms and synthetic methods of daphnetin, given its therapeutic potential in clinical. Despite these initial insights, the precise mechanisms underlying the pharmacological activities of daphnetin remain largely unknown. In order to address this knowledge gap, we explore the molecular effects from the perspectives of signaling pathways, NOD-like receptor protein 3 (NLRP3) inflammasome and inflammatory factors; and try to find out how these mechanisms can be utilized to inform new combined therapeutic strategies.

Role of Bioactive Compounds, Novel Drug Delivery Systems, and Polyherbal Formulations in the Management of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is an autoimmune disorder that generally causes joint synovial inflammation as well as gradual cartilage and degenerative changes, resulting in progressive immobility. Cartilage destruction induces synovial inflammation, including synovial cell hyperplasia, increased synovial fluid, and synovial pane development. This phenomenon causes articular cartilage damage and joint alkalosis. Traditional medicinal system exerts their effect through several cellular mechanisms, including inhibition of inflammatory mediators, oxidative stress suppression, cartilage degradation inhibition, increasing antioxidants and decreasing rheumatic biomarkers. The medicinal plants have yielded a variety of active constituents from various chemical categories, including alkaloids, triterpenoids, steroids, glycosides, volatile oils, flavonoids, lignans, coumarins, terpenes, sesquiterpene lactones, anthocyanins, and anthraquinones. This review sheds light on the utilization of medicinal plants in the treatment of RA. It explains various phytoconstituents present in medicinal plants and their mechanism of action against RA. It also briefs about the uses of polyherbal formulations (PHF), which are currently in the market and the toxicity associated with the use of medicinal plants and PHF, along with the limitations and research gaps in the field of PHF. This review paper is an attempt to understand various mechanistic approaches employed by several medicinal plants, their possible drug delivery systems and synergistic effects for curing RA with minimum side effects.

Daphnetin Improves Neuropathic Pain by Inhibiting the Expression of Chemokines and Inflammatory Factors in the Spinal Cord and Interfering with Glial Cell Polarization

Neuropathic pain (NP) is a common pain disease that seriously affects the quality of life and physical and mental health of patients. Daphnetin is extracted from the Daphne giraldii Nitsche and has the structure of 7,8-dihydroxy coumarin. As a natural product, daphnetin displays a wide range of pharmacological activities, such as analgesia and anti-inflammatory activities, but whether it is able to improve NP through anti-inflammatory effects is unknown. Therefore, this paper intends to investigate the mechanism of daphnetin in improving NP rats affected by the intrathecal injection of tumor necrosis factor-α (TNF-α) from the perspective of anti-inflammation. Our results showed that daphnetin significantly improved hyperalgesia in NP rats. Daphnetin inhibited the activation and polarization of glial cells and neurons in the spinal cord of NP rats and reduced the expression of mRNA and protein of inflammatory factors and chemokine pairs in the spinal cord. Daphnetin inhibited the polarization of human microglia cell 3 (HMC3) cells and human glioma cells (U251) cells toward M1 microglia and A1 astrocytes, respectively, and induced the conversion of M1 microglia and A1 astrocytes to M2 microglia and A2 astrocytes, respectively. In conclusion, daphnetin ameliorates NP by inhibiting the expression of inflammatory factors and chemokines and the polarization of glial cells in the spinal cord of NP rats. This study provides a theoretical basis for the treatment of NP with daphnetin to expand the clinical application of daphnetin.

Daphnetin: A bioactive natural coumarin with diverse therapeutic potentials

Daphnetin (DAP), a coumarin derivative extracted from Daphne species, is biologically active phytochemical with copious bioactivities including anti-inflammatory, anti-oxidant, neuroprotective, analgesic, anti-pyretic, anti-malarial, anti-bacterial, anti-arthritic, neuroprotective, hepatoprotective, nephroprotective, and anti-cancer activities. A wide range of studies have been conducted exploring the significance and therapeutic potential of DAP. This study reviewed various databases such as NCBI, PubMed, Web of Science, Scopus and Google Scholar for published research articles regarding the sources, synthesis, and various bioactivities of DAP using different key words, including but not limited to “pharmacological activities,” “sources,” “neuroprotective effect,” “synthesis,” “cancer,” “anti-inflammatory effect” of “daphnetin.” Furthermore, this review encompasses both in-vivo and in-vitro studies on DAP for treating various diseases. A comprehensive review of the literature revealed that the DAP had a promising pharmacological and safety profile, and could be employed as a pharmaceutical moiety to treat a variety of illnesses including microbial infections, cancer, arthritis, hepatic damage, inflammation and neurological anomalies. The current review intends to provide an in-depth focus on all pharmacological activities and therapeutic approaches for the pharmaceutical and biomedical researchers.

Daphnetin, a Coumarin in Genus Stellera Chamaejasme Linn: Chemistry, Bioactivity and Therapeutic Potential

Coumarins is a huge family of phenolic compounds containing a common structure of 2 H -1-benzopyran-2-one. Nowadays, more than 1,300 natural-based coumarins have been identified in a variety of plants, bacteria and fungi, many of them exhibited promising biomedical performance. Daphnetin (7,8-dihydroxycoumarin) is a typical coumarin associated with a couple of bioactivities such as anti-cancer, antibacterial, anti-inflammatory and anti-arthritis. In the treatment of diseases, it has been verified that daphnetin has outstanding therapeutic effects on diabetes, arthritis, transplant rejection, cancer and even on central nervous system diseases. Herein, we summarized the chemical synthetic methodologies, bioactivities, therapeutic potentials and structure-activity relationships of daphnetin and its derivatives. Hopefully, this review would be beneficial for the discovery of new coumarin-based biomedicine in the near future.

Screening for Active Compounds Targeting Human Natural Killer Cell Activation Identifying Daphnetin as an Enhancer for IFN-γ Production and Direct Cytotoxicity

Natural killer (NK) cells are a potent weapon against tumor and viral infection. Finding active compounds with the capacity of enhancing NK cell effector functions will be effective to develop new anti-cancer drugs. In this study, we initially screened 287 commercially available active compounds by co-culturing with peripheral blood mononuclear cells (PBMCs). We found that five compounds, namely, Daphnetin, MK-8617, LW6, JIB-04, and IOX1, increased the IFN-γ⁺ NK cell ratio in the presence of IL-12. Further studies using purified human primary NK cells revealed that Daphnetin directly promoted NK cell IFN-γ production in the presence of IL-12 but not IL-15, while the other four compounds acted on NK cells indirectly. Daphnetin also improved the direct cytotoxicity of NK cells against tumor cells in the presence of IL-12. Through RNA-sequencing, we found that PI3K-Akt-mTOR signaling acted as a central pathway in Daphnetin-mediated NK cell activation in the presence of IL-12. This was further confirmed by the finding that both inhibitors of PI3K-Akt and its main downstream signaling mTOR, LY294002, and rapamycin, respectively, can reverse the increase of IFN-γ production and cytotoxicity in NK cells promoted by Daphnetin. Collectively, we identify a natural product, Daphnetin, with the capacity of promoting human NK cell activation via PI3K-Akt-mTOR signaling in the presence of IL-12. Our current study opens up a new potential application for Daphnetin as a complementary immunomodulator for cancer treatments.

Nutraceuticals in the Prevention of Neonatal Hypoxia-Ischemia: A Comprehensive Review of their Neuroprotective Properties, Mechanisms of Action and Future Directions

Neonatal hypoxia–ischemia (HI) is a brain injury caused by oxygen deprivation to the brain due to birth asphyxia or reduced cerebral blood perfusion, and it often leads to lifelong limiting sequelae such as cerebral palsy, seizures, or mental retardation. HI remains one of the leading causes of neonatal mortality and morbidity worldwide, and current therapies are limited. Hypothermia has been successful in reducing mortality and some disabilities, but it is only applied to a subset of newborns that meet strict inclusion criteria. Given the unpredictable nature of the obstetric complications that contribute to neonatal HI, prophylactic treatments that prevent, rather than rescue, HI brain injury are emerging as a therapeutic alternative. Nutraceuticals are natural compounds present in the diet or used as dietary supplements that have antioxidant, anti-inflammatory, or antiapoptotic properties. This review summarizes the preclinical in vivo studies, mostly conducted on rodent models, that have investigated the neuroprotective properties of nutraceuticals in preventing and reducing HI-induced brain damage and cognitive impairments. The natural products reviewed include polyphenols, omega-3 fatty acids, vitamins, plant-derived compounds (tanshinones, sulforaphane, and capsaicin), and endogenous compounds (melatonin, carnitine, creatine, and lactate). These nutraceuticals were administered before the damage occurred, either to the mothers as a dietary supplement during pregnancy and/or lactation or to the pups prior to HI induction. To date, very few of these nutritional interventions have been investigated in humans, but we refer to those that have been successful in reducing ischemic stroke in adults. Overall, there is a robust body of preclinical evidence that supports the neuroprotective properties of nutraceuticals, and these may represent a safe and inexpensive nutritional strategy for the prevention of neonatal HI encephalopathy.

Daphnetin suppresses experimental abdominal aortic aneurysms in mice via inhibition of aortic mural inflammation

Rupture of abdominal aortic aneurysm (AAA) is a devastating event that can be prevented by inhibiting the growth of small aneurysms. Therapeutic strategies targeting certain events that promote the development of AAA must be developed, in order to alter the course of AAA. Chronic inflammation of the aortic mural is a major characteristic of AAA and is related to AAA formation, development and rupture. Daphnetin (DAP) is a coumarin derivative with anti-inflammatory properties that is extracted from Daphne odora var. However, the effect of DAP on AAA development remains unclear. The present study investigated the effect of DAP on the formation and development of experimental AAAs and its potential underlying mechanisms. A mice AAA model was established by intra-aortic infusion of porcine pancreatic elastase (PPE), and mice were intraperitoneally injected with DAP immediately after PPE infusion. The maximum diameter of the abdominal aorta was measured by ultrasound system, and aortic mural changes were investigated by Elastica van Gieson (EVG) staining and immunohistochemical staining. The results demonstrated that DAP significantly suppressed PPE-induced AAA formation and attenuated the depletion of aortic medial elastin and smooth muscle cells in the media of the aorta. Furthermore, the density of mural macrophages, T cells and B cells were significantly attenuated in DAP-treated AAA mice. In addition, treatment with DAP resulted in a significant reduction in mural neovessels. These findings indicated that DAP may limit the formation and progression of experimental aneurysms by inhibiting mural inflammation and angiogenesis. These data confirmed the translational potential of DAP inclinical AAA inhibition strategies.

Daphnetin induces apoptosis in fibroblast-like synoviocytes from collagen-induced arthritic rats mainly via the mitochondrial pathway

Rheumatoid arthritis (RA) is a chronic, symmetric, systemic autoimmune disease. Because insufficient apoptosis of fibroblast-like synoviocytes (FLS) is an important characteristic of RA, promoting apoptosis is considered a potential therapeutic tool for treating RA. We have previously found that daphnetin (7,8-dihydroxycoumarin, DAP) has a pro-apoptotic effect on fibroblast-like synoviocytes from collagen-induced arthritis (CIA) rats. In the present study, we further investigated the mechanisms of DAP-induced apoptosis in CIA-FLS. CIA-FLS were incubated with DAP for 48 h in the presence or absence of caspase inhibitors, including inhibitors of caspase-3, caspase-8, or caspase-9 or a pan-caspase inhibitor; then, a series of experiments were performed to evaluate the mechanisms of DAP-induced apoptosis. Our results showed that DAP markedly decreased cell viability and induced the apoptosis of CIA-FLS along with typical morphological and ultrastructural changes; moreover, DAP increased FasL, cytochrome c (Cyt-c), Bax, caspase-3, caspase-8, and caspase-9 mRNA expression and Bax, caspase-3, caspase-8, and caspase-9 protein expression. In contrast, DAP decreased Bcl-2 mRNA and protein expression and promoted the release of Cyt-c from the mitochondria into the cytosol; these effects were attenuated to varying degrees by pre-treatment with caspase inhibitors, especially with caspase-3 or caspase-9 inhibitors or a pan-caspase inhibitor. In conclusion, the current findings demonstrate that the DAP-induced apoptosis of CIA-FLS occurred mainly via a caspase-dependent pathway, in particular the mitochondrial pathway, and that the Bax/Bcl-2 ratio was involved in this process. Thus, DAP may be a potential therapeutic agent for RA.

An herbal formula inhibits STAT3 signaling and attenuates bone erosion in collagen-induced arthritis rats

BACKGROUND

Receptor activator of NF-κB ligand (RANKL) facilitates differentiation of osteoclast precursors into osteoclasts, resulting in bone erosion in rheumatoid arthritis (RA) patients. Fibroblast-like synoviocytes (FLS) are the main cells for producing RANKL. Signal transducer and activator of transcription 3 (STAT3) signaling is activated in FLS of RA patients (RA-FLS), which has been linked to RANKL production. A two-herb formula (RL) comprising Rosae Multiflorae Fructus and Lonicerae Japonicae Flos is traditionally used for treating RA in China. We have found that a standardized ethanolic extract of RL (RLE for short) alleviates bone erosion in collagen-induced arthritis (CIA) rats.

PURPOSE

This study aimed to determine whether RLE inhibits RANKL production and osteoclastogenesis in cell and rat models, and to explore the involvement of the STAT3 pathway in this inhibition.

STUDY DESIGN AND METHODS

A CIA rat model, interleukin-6/soluble interleukin-6 receptor (IL-6/sIL-6R)-stimulated RA-FLS and a co-culture system (IL-6/sIL-6R-stimulated RA-FLS/peripheral blood mononuclear cells) were used to evaluate the effects of RLE. Micro-computed tomography analysis was used to observe bone erosion in CIA rats. Tartrate-resistant acid phosphatase staining was used to evaluate osteoclastogenesis. Western blotting and ELISA assays were employed to examine protein levels. RT-qPCR was used to detect mRNA levels. STAT3-over-activated RA-FLS were used to investigate the involvement of STAT3 signaling in the anti-osteoclastogenic effects of RLE.

RESULTS

RLE alleviated bone erosion in joints of CIA rats. In both synovial tissues of CIA rats and IL-6/sIL-6R-stimulated RA-FLS, RLE downregulated the protein level of RANKL. In the co-culture system, RLE significantly and dose-dependently inhibited IL-6/sIL-6R-induced osteoclastogenesis. Mechanistic studies revealed that RLE lowered the protein level of phospho-STAT3 (Tyr705) in synovial tissues of CIA rats. In IL-6/sIL-6R-stimulated RA-FLS, RLE inhibited the activation/phosphorylation of a STAT3 upstream kinase Janus kinase 2 (Tyr1007/1008) and STAT3 (Tyr705), decreased the nuclear localization of STAT3, lowered mRNA levels of STAT3-transcriptionally regulated genes IL-1β and TNF-α. RLE's inhibitory effects on RANKL production in RA-FLS gradually decreased when IL-6/sIL-6R doses increased. Over-activation of STAT3 diminished the inhibitory effects of RLE on RANKL production in IL-6/sIL-6R-stimulated RA-FLS, and attenuated the anti-osteoclastogenic effects of RLE in the co-culture system.

CONCLUSION

We, for the first time, demonstrated that suppressing STAT3 signaling contributes to the inhibition of RANKL production and osteoclastogenesis, and thereby supports the mechanisms responsible for the reduction in bone erosion in RLE-treated CIA rats. This study provides further pharmacological groundwork for developing RLE as a modern anti-arthritic drug, and supports the notion that targeting STAT3 signaling is a viable strategy for managing bone erosion.

Coumarins as Modulators of the Keap1/Nrf2/ARE Signaling Pathway

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

Daphne giraldii Nitsche (Thymelaeaceae): Phytochemistry, pharmacology and medicinal uses

Daphne giraldii Nitsche., a member of the genus Daphne (Thymelaeaceae), is a deciduous shrub with mild toxicity. Its rhizome bark, generally called 'Zushima' in Chinese, has many medicinal folkloric uses and good therapeutic effects. Previous studies investigating the chemical constituents and pharmacological activities of D. giraldii have focused on several major classes of compounds, such as coumarins, lignans and flavonoids, especially the interesting enantiomeric flavans. Extracts and pure compounds of D. giraldii were found to possess anti-inflammatory, anti-nociceptive, cytotoxicity, antimalarial, immunomodulating, sedative and hypnotic effects. They have also been reported to influence the cardiovascular functions and blood activities. This comprehensive review will describe the advances in the phytochemistry, pharmacology, medicinal uses and clinical applications of D. giraldii and its formulations covering the literature published from 1970 to 2018. Almost half of the reviewed studies were originally published in non-English languages (mainly in Chinese). Collectively, the aim of this article is to open new avenues for further in-depth pharmacological studies on D. giraldii.

Daphnetin Ameliorates Experimental Autoimmune Encephalomyelitis Through Regulating Heme Oxygenase-1

To assess the potential role of daphnetin, a clinically used anti-inflammatory agent, on the development of the inflammatory and neurodegenerative disease, we investigated its immune regulatory function in a murine model of experimental autoimmune encephalomyelitis (EAE). Significantly, lower levels of pro-inflammatory cytokines including interleukin (IL)-17, interferon-γ, Il6, Il12a, and Il23a were observed in brains of daphnetin-treated EAE mice, compared with those in control littermates. We also confirmed that daphnetin suppressed the production of IL-1β, IL-6, and tumor necrosis factor-α in lipopolysaccharide-stimulated mouse BV2 microglial cells. Mechanistically, heme oxygenase-1 (HO-1), a canonical anti-oxidant and anti-inflammatory factor, was found to be substantially induced by daphnetin treatment in BV2 cells. Also, a significantly higher level of HO-1, accompanied by a decreased level of malondialdehyde, was observed in daphnetin-treated EAE mice. More importantly, the deletion of HO-1 in BV2 microglia largely abrogated daphnetin-mediated inhibition of the inflammatory response. Together, our data demonstrate that daphnetin has an anti-inflammatory and neuroprotective role during the pathogenesis of EAE, which is partially at least, dependent on its regulation of HO-1.

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.

[Effects of daphnetin combined with insulin-like growth factor 1 on chondrogenic differentiation of adipose-derived mesenchymal stem cells in rats]

OBJECTIVE

To investigate the effect of daphnetin (DAP) combined with insulin-like growth factor 1 (IGF-1) gene transfection on chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) in rats.

METHODS

Rat ADSCs were isolated and amplified by enzymatic digestion. The third generation ADSCs were treated with IGF-1 gene transfection as experimental group and normal ADSCs as control group. The cells of the two groups were treated with different concentrations of DAP (0, 30, 60, 90 μg/mL), respectively. Cell proliferation was detected by cell counting kit 8 (CCK-8) after cultured for 72 hours. After 14 days, real-time fluorescence quantitative PCR and Western blot were used to detect the mRNA and protein expressions of chondrocyte markers (collagen type Ⅱ and Aggrecan) in each group; and toluidine blue staining and collagen type Ⅱ immunohistochemical staining were performed.

RESULTS

CCK-8 assay showed that with the increase of DAP concentration, the cell absorbance ( A) value of the control group and the experimental group increased gradually ( P<0.05). At the same DAP concentration, the cell A value of the experimental group was significantly higher than that of the control group ( P<0.05). Real-time fluorescence quantitative PCR and Western blot showed that with the increase of DAP concentration, the relative mRNA and protein expressions of collagen type Ⅱ and Aggrecan in the control group did not change significantly, and there was no significant difference among the different concentration groups ( P>0.05). But the mRNA and protein expressions of collagen type Ⅱ and Aggrecan in the experimental group increased gradually, and the 60 and 90 μg/mL DAP concentration groups were significantly higher than 0 μg/mL DAP concentration group ( P<0.05). At the same DAP concentration, the relative mRNA and protein expressions of collagen type Ⅱ and Aggrecan were significantly higher in the experimental group than in the control group ( P<0.05). Toluidine blue staining showed that with the increase of DAP concentration, there was no significant difference in cell staining between the control group and the experimental group. At the same DAP concentration, the cells in the experimental group were slightly darker than those in the control group. Immunohistochemical staining of collagen type Ⅱ showed that with the increase of DAP concentration, there was no significant difference in the cytoplasmic brown-yellow coloring of the cells in the control group. The cytoplasmic brown-yellow coloring of the cells in the experimental group gradually deepened, with 60 and 90 μg/mL DAP concentration groups significantly deeper than 0 μg/mL DAP concentration group. At the same DAP concentration, the color of the cells in the experimental group was significantly deeper than that in the control group.

CONCLUSION

DAP can promote the proliferation of ADSCs in rats. The differentiation of ADSCs into chondrocytes induced by DAP alone was slightly, but DAP combined with IGF-1 gene transfection has obvious synergistic effect to promote chondrogenic differentiation of ADSCs.

Daphnetin ameliorates experimental colitis by modulating microbiota composition and Treg/Th17 balance

Inflammatory bowel diseases (IBDs) are characterized by chronic pathologies associated with extensive gut dysbiosis and intestinal inflammation. Hence, endeavors to improve the inflammatory pathology by manipulating gut microbiota are ongoing. Daphnetin (DAPH) is a coumarin derivative extracted from Daphne odora var with anti-inflammatory and immune-regulatory properties that has been widely used in treating inflammatory disorders. Herein, we showed that DAPH remarkably alleviated experimental colitis by reducing colonic inflammation, improving colonic integrity, and reestablishing immune and metabolic homeostasis in the inflicted intestines. Our analysis showed that DAPH modified the composition of gut microbiota and altered the metabolic profiles in dextran sulfate sodium-treated mice. In particular, this agent significantly elevated the abundance of short-chain fatty acid (SCFA)-producing gut microbiota, causatively related with the enhanced development of T_reg cells and the reduced proinflammatory T_h17 cell differentiation. More critically, the protective effect of DAPH was shown to be transmissible among colitic mice through cohousing or fecal microbiota transplantation, further substantiating the importance of SCFA-producing gut microbiota in DAPH action. We thus for the first time reveal the potential of DAPH in resetting the gut microbiome and reestablishing immune homeostasis in colitic mice, which may have clinical implications for treating IBD.-Ji, J., Ge, X., Chen, Y., Zhu, B., Wu, Q., Zhang, J., Shan, J., Cheng, H., Shi, L. Daphnetin ameliorates experimental colitis by modulating microbiota composition and T_reg/T_h17 balance.

Daphnetin prevents methicillin-resistant Staphylococcus aureus infection by inducing autophagic response

The bacterial pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) is a potentially fatal disease, featured with extensive infection, inflammation, and airway dysfunction. With the increasing emerging of drug-resistant strains, new therapeutic strategies beyond canonical antibiotic treatment are pressingly needed. Daphnetin (DAPH) is a natural coumarin derivative with anti-inflammation, anti-microorganism and anti-oxidative properties. However, the protective effect of DAPH on S. aureus-caused pneumonia and the mechanism involved are never explored. Here we show that DAPH treatment conferred substantial protection against S. aureus-induced pneumonia, characterized by the reduced inflammatory responses, the augmented bacterial clearance and the alleviated tissue damage. Our study indicates that DAPH significantly enhanced mTOR-dependent autophagic pathway, leading to the boosted microphage bactericidal activity and the suppressed inflammatory responses. Inhibition of autophagic pathway therefore largely abolished DAPH-elicited repression of inflammatory response and macrophage anti-bacterial capability. Together, we herein not only identify a novel, natural agent to combat bacterial pneumonia, but also underscore the significance of autophagic pathway in orchestrating antimicrobial and anti-inflammatory responses, which may have important implication for the treatment of the infectious diseases, particularly that caused by obstinate, antibiotic-resistant pathogens such as MRSA.

The phytochemistry, pharmacokinetics, pharmacology and toxicity of Euphorbia semen

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia semen, the dried and ripe seed of Euphorbia lathyris Linnaeus, is widely cultivated for traditional medicine use. This semen is used to expel water, help with phlegm retention, promote blood circulation, remove blood stasis, cure tinea and scabies, and treat amenorrhea, snakebites, terminal schistosomiasis, anuria and constipation.

AIM OF THE REVIEW

This review provides updated, comprehensive and categorized information on the local and traditional uses, phytochemistry, pharmacokinetics, pharmacological activities and toxicity of Euphorbia semen. Future research to deepen the recognition and utilization of Euphorbia semen is proposed.

MATERIALS AND METHODS

This article conducted a literature review on information about Euphorbia semen in multiple Internet databases, including PubMed, Web of Science, Wiley, Science Direct, Elsevier, ACS publications, SciFinder, Google Scholar and China National Knowledge Internet, until March of 2018. In this manuscript, a number of books, PhD and MSc dissertations, and Chinese Pharmacopeia were also used as references.

RESULTS

Approximately 240 chemical constituents have been isolated and identified from Euphorbia semen, namely, diterpenoids, coumarins, flavonoids, fatty acids, amino acids, and steroids. Pharmacokinetic study focused on investigating absorption, distribution, metabolism and excretion (ADME). The chemical constituents have extensive pharmacological effects, such as diuresis and anti-hyperuricaemia, anti-inflammation, antiviral, anticancer, antioxidant, antipigmentation, anti-platelet aggregation and anti-allergic activities, as well as hepatoprotection and neuroprotection. The toxicity of Euphorbia semen, including acute toxicity, target organ irritation and cocareinogenic effects, have been reported, and the detoxification methods are reviewed.

CONCLUSION

Euphorbia semen has extensive pharmacological activity and excellent clinical value, along with intense intestinal irritation. Although plenty of chemical constituents have been isolated and identified, the exact pharmacological and toxicological mechanisms still need to be explored.

Toll-Like Receptor 2 Signaling and Current Approaches for Therapeutic Modulation in Synucleinopathies

The innate immune response in the central nervous system (CNS) is implicated as both beneficial and detrimental to health. Integral to this process are microglia, the resident immune cells of the CNS. Microglia express a wide variety of pattern-recognition receptors, such as Toll-like receptors, that detect changes in the neural environment. The activation of microglia and the subsequent proinflammatory response has become increasingly relevant to synucleinopathies, including Parkinson's disease the second most prevalent neurodegenerative disease. Within these diseases there is evidence of the accumulation of endogenous α-synuclein that stimulates an inflammatory response from microglia via the Toll-like receptors. There have been recent developments in both new and old pharmacological agents designed to target microglia and curtail the inflammatory environment. This review will aim to delineate the process of microglia-mediated inflammation and new therapeutic avenues to manage the response.

Effects of daphnetin combined with Bcl2‑siRNA on antiapoptotic genes in synovial fibroblasts of rats with collagen‑induced arthritis

The aim of the present study was to investigate the effects of daphnetin combined with B cell lymphoma 2 (Bcl2)‑targeted small interfering (si)RNA (si‑Bcl2) on antiapoptotic genes in fibroblast‑like synoviocytes (FLS) in rats with collagen II‑induced arthritis (CIA). The roles of si‑Bcl2 and daphnetin were determined by measuring the expression levels of Bcl2. Protein and mRNA expression levels of Bcl2 in FLS were determined by flow cytometry and reverse transcription‑quantitative polymerase chain reaction. Apoptosis of FLS was also determined by flow cytometry. It was revealed that treatment with si‑Bcl2 or daphnetin alone resulted in downregulation of Bcl2 mRNA and protein expression. In addition, the mRNA expression levels of the signal transducer and activator of transcription 3 (STAT3), which transcriptionally regulates the activity of mitochondria, were reduced. The combination of si‑Bcl2 and daphnetin exhibited an enhanced effect on rheumatoid arthritis FLS (RAFLS), in which the apoptotic rate was significantly higher than either treatment alone. The results suggested that si‑Bcl combined with daphnetin may have an enhanced effect in promoting apoptosis of RAFLS derived from CIA rats, and a possible underlying molecular mechanism may function through the downregulation of Bcl2 expression and STAT3, which is located upstream of Bcl2 in the mitochondrial apoptotic pathway. The results of the present study are expected to provide theoretical and experimental basis for the treatment of RA and the medicinal development of daphnetin combined siRNA.

Daphnetin inhibits TNF-α and VEGF-induced angiogenesis through inhibition of the IKKs/IκBα/NF-κB, Src/FAK/ERK1/2 and Akt signalling pathways

Coumarins, identified as plant secondary metabolites possess diverse biological activities including anti-angiogenic properties. Daphnetin (DAP), a plant derived dihydroxylated derivative of coumarin has shown significant pharmacological properties such as anticancer, anti-arthritic and anti-inflammatory. The present study was performed to investigate the anti-angiogenic potential of DAP, focusing on the mechanism of action. The in vivo anti-angiogenic potential of DAP was evaluated by vascular endothelial growth factor (VEGF)-induced rat aortic ring (RAR) assay and chick chorioallantoic membrane (CAM) assay. For in vitro evaluation, wounding migration, transwell invasion, tube formation and apoptosis assays were performed on VEGF (8 ng/mL)-induced human umbilical vein endothelial cells (HUVECs). The cellular mechanism of DAP was examined on TNFα (10 ng/mL) and VEGF-induced HUVECs by extracting the mRNA and protein levels using RT-qPCR and western blotting. Our data demonstrated that DAP inhibited the in vivo angiogenesis in the RAR and CAM assay. DAP also inhibited the different steps of angiogenesis, such as migration, invasion, and tube formation in HUVECs. DAP inhibited nuclear factor-κB signalling together including TNF-α induced IκBα degradation; phosphorylation of IκB kinase (IKKα/β) and translocation of the NF-κB-p65 protein. Furthermore, western blotting revealed that DAP significantly down-regulated the VEGF-induced signalling such as c-Src, FAK, ERK1/2 and the related phosphorylation of protein kinase B (Akt) and VEGFR2 expressions. DAP reduced the elevated mRNA expression of iNOS, MMP2 and also, induced apoptosis in VEGF-stimulated HUVECs by the caspase-3 dependent pathway. Taken together, this study reveals that DAP may have novel prospective as a new multi-targeted medication for the anti-angiogenesis and cancer therapy.

Matrine regulates Th1/Th2 cytokine responses in rheumatoid arthritis by attenuating the NF-κB signaling

To investigate the efficacy and mechanisms of matrine, a component derived from Sophora flavescens in treatment of rheumatoid arthritis (RA), a rat model of RA was established. Compared to control rats, matrine significantly mitigated inflammation and severity of RA (paw volume and articular index (AI) score). Using either mice splenic T cells stimulated with PMA/ionomycin or rat splenic T cells, the levels of Th1 and Th2 responses were determined by flow cytometry, quantitative RT-PCR, and ELISA. Furthermore, the levels of NF-κBp65 (RelA), IκBα, and phosphor-IκBα in T cells were determined by Western blot. Our study found that matrine modulated the imbalance of Th1 and Th2 cytokine responses in rats with RA by reducing the levels of Th1 cytokines (IFN-γ, TNF-α, IL-1β), but increasing Th2 cytokine (IL-4 and IL-10) through attenuating the NF-κB signaling in T cells, suggesting matrine as a promising drug for intervention of RA.

Daphnetin Protects against Cerebral Ischemia/Reperfusion Injury in Mice via Inhibition of TLR4/NF-κB Signaling Pathway

Growing evidences indicate that immune-mediated mechanisms contribute to the development of cerebral ischemia/reperfusion (I/R) injury. Daphnetin (DAP) is a coumarin derivative extracted from Daphne odora var., which displays anti-inflammatory properties. However, the effect of DAP on cerebral I/R injury is not yet clear. Recent studies have demonstrated that TLR4/NF-κB signaling pathway takes part in the damaging inflammatory process of cerebral I/R injury. The present study aimed to investigate the effect of DAP on cerebral I/R injury in vivo and its possible mechanisms. DAP was administered before middle cerebral artery occlusion and reperfusion in mice. The neurological scores, cerebral infarct sizes, the levels of inflammatory cytokines, apoptotic neural cells, and the levels of TLR4, NF-κB p65, and IκBα were estimated. The results showed that an obvious improvement of neurological scores and infarct sizes was observed in DAP-treated mice after MCAO/R. DAP treatment decreased the overexpression of TNF-α, IL-1β, and IL-6 and attenuated neural cells apoptosis. Moreover, DAP treatment decreased the TLR4 expression, IκB-α degradation, and nuclear translocation of NF-κB. Taken together, our results suggested that DAP exerted neuroprotective and anti-inflammatory effects on cerebral I/R injury. The potential mechanism was involved in the inhibition of TLR4/NF-κB mediated inflammatory signaling pathway.

Role of Daphnetin in Rat Severe Acute Pancreatitis Through the Regulation of TLR4/NF-[Formula: see text]B Signaling Pathway Activation

Severe acute pancreatitis (SAP) often results in multiple-organ dysfunction syndrome with high mortality. There is no effective clinical therapy for SAP, yet daphnetin, a coumarin extracted from Dracaena marginata, has analgesic and anti-inflammatory effects, and has been used clinically in several diseases. The objective of this study was to investigate the role and underlying mechanisms of daphnetin in a rat SAP model. Male Wistar rats were pretreated with daphnetin via intraperitoneal injection, 30[Formula: see text]min before retrograde infusion of 5% sodium taurocholate into the biliopancreatic duct. Twelve hours after sodium taurocholate administration, rats were sacrificed and tissues and blood were harvested. Then, histological, chemical, and molecular analyses were performed. Daphnetin treatment reduced the levels of serum alanine transaminase and creatinine (CR), increased superoxide dismutase(SOD) activity, and decreased neutrophil infiltration and cell apoptosis of the pancreatic tissues in rat SAP. Daphnetin treatment significantly decreased expression of pro-inflammatory cytokines and increased expression of anti-inflammatory cytokines in rat SAP. Molecular analyses revealed that daphnetin reduced TLR4 expression and inhibited NF-[Formula: see text]B signaling pathway activation. These findings demonstrate that daphnetin attenuates acute pancreatic injury by regulating the TLR4/NF-[Formula: see text]B signaling pathway and inflammation in rat SAP model. Daphnetin may be a potential therapeutic agent for SAP.

Daphnetin inhibits inflammation in the NZB/W F1 systemic lupus erythematosus murine model via inhibition of NF-κB activity

Daphnetin is a compound extracted from Chinese medicinal herbs, which exerts analgesic and anti-inflammatory effects. The present study aimed to investigate the potential therapeutic effect of daphnetin on inflammation in the NZB/W F1 systemic lupus erythematosus (SLE) murine model. Female NZB/WF1 mice (age, 16–18 weeks) were intraperitoneally injected with daphnetin once a day for 12 weeks. It was revealed that daphnetin treatment significantly increased animal survival rates, reduced renal damage and blood urea nitrogen levels, and suppressed serum autoantibody production in the SLE-prone NZB/W F1 mice. In addition, daphnetin treatment significantly decreased the serum levels of tumor necrosis factor-α and interleukin-6, inhibited nuclear factor (NF)-κB activity, suppressed the protein expression of nuclear factor of activated T-cells and promoted A20 protein expression in SLE-prone NZB/W F1 mice. In conclusion, daphnetin inhibited inflammation in the NZB/W F1 murine SLE model via inhibition of NF-κB mediated by upregulation of A20.

Daphnetin Alleviates Experimental Autoimmune Encephalomyelitis via Regulating Dendritic Cell Activity

AIMS

Daphnetin, a coumarin derivative extracted from Daphne odora var. marginata, has been reported to have antiinflammatory and immunosuppressive properties. Our previous study indicated that it was able to remarkably suppress the neuroinflammation and suggested its potential application in treating neuroinflammatory diseases. Multiple sclerosis (MS), a Th cell-mediated autoimmune disease, is the most common inflammatory demyelinating disease of the central nervous system (CNS). We examined whether daphnetin treatment can protect mice against experimental autoimmune encephalomyelitis (EAE), an animal model for MS.

METHODS

To assess the effect of daphnetin in neuroinflammatory diseases, the EAE mice were established and treated with daphnetin at 8 mg/kg for 28 days. The severity of neuroinflammation and demyelination in the spinal cords was examined histopathologically. Infiltration of CD4(+) T cells into the CNS was assessed by immunohistochemistry, and the cytokine production was determined by ELISA. Meanwhile, the effect of daphnetin on the activity of dendritic cells (DCs) was evaluated, as assessed by DCs' capability to express surface markers, secrete cytokines, and activate naïve CD4(+) T cells. Furthermore, we explored the molecular mechanisms whereby DAPH regulated DCs' activity and thereby CD4(+) T cell responses.

RESULTS

The administration of daphnetin markedly alleviated the clinical symptoms of EAE and reduced the CNS inflammation and demyelination in experimental mice. Th1 and Th17 cell responses were profoundly repressed in daphnetin-treated EAE mice. Mechanistically, daphnetin treatment significantly repressed the activation, maturation, and antigen-presenting capability of DCs. NF-κB signaling was significantly reduced in daphnetin-treated DCs, along with a concomitant induction of heme oxygenase-1, a negative regulator of inflammatory signaling.

CONCLUSIONS

Our findings for the first time demonstrate the property of daphnetin in regulating DCs' function and subsequently Th development. Given the low or absent toxicity associated with daphnetin, our data may suggest a novel safe and effective approach to control autoimmune neuroinflammation.

Daphnetin inhibits invasion and migration of LM8 murine osteosarcoma cells by decreasing RhoA and Cdc42 expression

Daphnetin, 7,8-dihydroxycoumarin, present in main constituents of Daphne odora var. marginatai, has multiple pharmacological activities including anti-proliferative effects in cancer cells. In this study, using a Transwell system, we showed that daphnetin inhibited invasion and migration of highly metastatic murine osteosarcoma LM8 cells in a dose-dependent manner. Following treatment by daphnetin, cells that penetrated the Transwell membrane were rounder than non-treated cells. Immunofluorescence analysis revealed that daphnetin decreased the numbers of intracellular stress fibers and filopodia. Moreover, daphnetin treatment dramatically decreased the expression levels of RhoA and Cdc42. In summary, the dihydroxycoumarin derivative daphnetin inhibits the invasion and migration of LM8 cells, and therefore represents a promising agent for use against metastatic cancer.

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.

The Role of IL-17 and Th17 Lymphocytes in Autoimmune Diseases

The end of twentieth century has introduced some changes into T helper (Th) cells division. The identification of the new subpopulation of T helper cells producing IL-17 modified model of Th1-Th2 paradigm and it was named Th17. High abilities to stimulate acute and chronic inflammation made these cells ideal candidate for crucial player in development of autoimmune disorders. Numerous publications based on animal and human models confirmed their pivotal role in pathogenesis of human systemic and organ-specific autoimmune diseases. These findings made Th17 cells and pathways regulating their development and function a good target for therapy. Therapies based on inhibition of Th17-dependent pathways are associated with clinical benefits, but on the other hand are frequently inducing adverse effects. In this review, we attempt to summarize researches focused on the importance of Th17 cells in development of human autoimmune diseases as well as effectiveness of targeting IL-17 and its pathways in pre-clinical and clinical studies.

Expression of receptor activator of nuclear factor-κB ligand is related to sex differences in collagen-induced arthritis

Osteoclasts are responsible for bone destruction in rheumatoid arthritis, and women show greater disease activity and functional disability than men. This study aimed to examine differences in the pathogenesis of collagen-induced arthritis and osteoclastogenesis between female and male mice in vivo and in vitro. Female mice exhibited worse disease progression and increased osteoclastogenesis, as measured by tartrate-resistant acid phosphatase (TRAP) staining than male mice. Significantly higher levels of CD11b(+) cells were detected in the bone marrow of female mice than that of male mice. Furthermore, the mRNA expression of receptor activator of nuclear factor-κB ligand was higher in female mice that were immunized with or without collagen II. These findings highlighted sex differences in arthritis morbidity and suggested that female mice are more likely to develop arthritis than male mice. Further studies are needed to investigate the mechanisms of sex differences in collagen-induced arthritis.

Immunosuppressive effect of Chinese medicine on T helper 17 cells

T helper (Th)17 cells have been proposed to play important roles in several human diseases. The literatures about Chinese medicine studies, which related to inhibiting Th17, were reviewed, and the Chinese medicine which could inhibit Th17 cells was summarized in this paper.

Anti-inflammatory and protective properties of daphnetin in endotoxin-induced lung injury

Uncontrolled inflammatory responses cause tissue injury and severe immunopathology. Pharmacological interference of intracellular pro-inflammatory signaling may confer a therapeutic benefit under these conditions. Daphnetin, a natural coumarin derivative, has been used to treat inflammatory diseases including bronchitis. However, the protective effect of daphnetin in inflammatory airway disorders has yet to be determined, and the molecular basis for its anti-inflammatory properties is unknown. This paper shows that daphnetin treatment conferred substantial protection from endotoxin-induced acute lung injury (ALI), in parallel with reductions in the production of inflammatory mediators, symptoms of airway response, and infiltration of inflammatory cells. Further studies indicate that activation of macrophage and human alveolar epithelial cells in response to lipopolysaccharide (LPS) was remarkably suppressed by daphnetin, which was related to the down-regulation of NF-κB-dependent signaling events. Importantly, this study demonstrates that TNF-α-induced protein 3 (TNFAIP3), also known as A20, was significantly induced by daphnetin, which appeared to be largely responsible for the down-regulation of NF-κB activity through modulation of nondegradative TRAF6 ubiquitination. Accordingly, the deletion of TNFAIP3 in primary macrophages reversed daphnetin-elicited inhibition of immune response, and the beneficial effect of daphnetin in the pathogenesis of ALI was, partially at least, abrogated by TNFAIP3 knockdown. These findings demonstrate the anti-inflammatory and protective functions of daphnetin in endotoxin-induced lung inflammation and injury and also reveal the key mechanism underlying its action in vitro as well as in vivo.

Therapeutic effect of daphnetin on the autoimmune arthritis through demethylation of proapoptotic genes in synovial cells

Background

We have previously reported that dephnetin is therapeutically effective in the treatment of rheumatoid arthritis (RA) in collagen-induced arthritis (CIA) rat model. However, the molecular mechanism and the effect of daphnetin on demethylating proapoptotic genes in the synovial cells remains further clarified. This study may provide a deeper insight into the medicinal application of daphnetin as a treatment for RA.

Methods

(1) The proliferation inhibition of CIA rat synovial cells was determined by an MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenyterazoliumromide) assay; (2) Methylation specific PCR (MSP) was used to measure the methylation of the proapoptotic genes DR3 (death receptor 3), PDCD5 (programmed cell death 5), FasL and p53; (3) Real time-PCR was performed to determine the mRNA expression of DR3, PDCD5, FasL, p53 and DNA methyltransferases (DNMTs) DNMT1, DNMT3a and DNMT3b; (4) Flow cytometry was applied to detect the protein expression of the DR3, PDCD5, FasL and p53; (5) The apoptotic rate of synovial cells was assessed by flow cytometry with Annexin V and propidium iodide (PI); (6) Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the changes of CIA rat synovial cell structure.

Results

(1) In the range of 1.25 μg/mL to 40 μg/mL, daphnetin and 5-aza-dc had a dose-dependent and time-dependent degree of inhibition to the CIA rat synovial cells. (2) Daphnetin and 5-aza-dc had a demethylating role on the proapoptotic genes DR3, PDCD5, FasL and p53 of CIA rat synovial cells. (3) Daphnetin and 5-aza-dc decreased the gene expression of methyltransferases DNMT1, DNMT3a and DNMT3b, and increased expression of proapoptotic genes DR3, PDCD5, FasL and p53, which translated into an increased protein expression of DR3, PDCD5, FasL and p53. (4) Daphnetin and 5-aza-dc changed the structure of CIA rat synovial cells to show apoptotic changes and increased the rate of apoptosis.

Conclusions

Daphnetin can reduce the expression of DNMT1, DNMT3a and DNMT3b, which could result in the proapoptotic genes DR3, PDCD5, FasL and p53 being demethylated. Therefore, daphnetin can increase proapoptotic gene and protein expression resulting in structural apoptotic changes and an increase in early and late CIA rat synovial cell apoptosis.

Immunosuppressive activity of daphnetin, one of coumarin derivatives, is mediated through suppression of NF-κB and NFAT signaling pathways in mouse T cells

Daphnetin, a plant-derived dihydroxylated derivative of coumarin, is an effective compound extracted from a plant called Daphne Korean Nakai. Coumarin derivates were known for their antithrombotic, anti-inflammatory, and antioxidant activities. The present study was aimed to determine the immunosuppressive effects and the underlying mechanisms of daphnetin on concanavalin A (ConA) induced T lymphocytes in mice. We showed that, in vitro, daphnetin suppressed ConA-induced splenocyte proliferation, influenced production of the cytokines and inhibited cell cycle progression through the G0/G1 transition. The data also revealed that daphnetin could down-regulate activation of ConA induced NF-κB and NFAT signal transduction pathways in mouse T lymphocyte. In vivo, daphnetin treatment significantly inhibited the 2, 4- dinitrofluorobenzene (DNFB) -induced delayed type hypersensitivity (DTH) reactions in mice. Collectively, daphnetin had strong immunosuppressive activity both in vitro and in vivo, suggesting a potential role for daphnetin as an immunosuppressive agent, and established the groundwork for further research on daphnetin.

Daphnetin attenuates microglial activation and proinflammatory factor production via multiple signaling pathways

Daphnetin, a natural coumarin derivative, is known to display anti-inflammatory properties and has been used to treat inflammatory diseases. A novel finding suggested that daphnetin might have a neuroprotective effect in stressed mice, leading us to explore its role in the microglial inflammatory response, as well as its underlying mechanism of action. We found that the production of pro-inflammatory mediators, including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), induced by lipopolysaccharide (LPS) or β-amyloid (Aβ) was significantly suppressed by daphnetin in a dose-dependent manner in BV2 microglia. Also, daphnetin inhibited LPS-induced nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and NO formation by microglia. Mechanistically, daphnetin blunted the transcriptional activity of nuclear factor-kappa B (NF-κB), which was associated with the down-regulation of the phosphorylation and nuclear translocation of RelA/p65. Inhibitors of kappa B (IκB) phosphorylation and degradation were also affected by daphnetin, which was likely due to the reduced activation of IκB kinase (IKK). Additionally, LPS-induced activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK, were, to a varying extent, altered by daphnetin. Finally, daphnetin blocked phosphatidylinositol-3 kinase (PI-3K)/protein kinase B (Akt) signaling in LPS-activated microglia, which appeared to at least partially account for the reduction in NF-κB transcriptional activity. Thus, daphnetin inhibited microglial activation and proinflammatory responses by modulating a series of intracellular signaling pathways, including IKK/IκB, MAPKs and PI-3K/Akt.

Daphnetin, a natural coumarin derivative, provides the neuroprotection against glutamate-induced toxicity in HT22 cells and ischemic brain injury

Daphnetin (DAP), a coumarin derivative, has been reported to have multiple pharmacological actions including analgesia, antimalarial, anti-arthritic, and anti-pyretic properties. It is unclear whether DAP has neuroprotective effects on ischemic brain injury. In this study, we found that DAP treatment (i.c.v.) reduced the infarct volume at 24 h after ischemia/reperfusion injury and improved neurological behaviors in a middle cerebral artery occlusion mouse model. Moreover, we provided evidences that DAP had protective effects on infarct volume in neonate rats even it was administrated at 4 h after cerebral hypoxia/ischemia injury. To explore its neuroprotective mechanisms of DAP, we examined the protection of DAP on glutamate toxicity-induced cell death in hippocampal HT-22 cells. Our results demonstrated that DAP protected against glutamate toxicity in HT-22 cells in a concentration-dependent manner. Further, we found that DAP maintained the cellular levels of glutathione and superoxide dismutase activity, suggesting the anti-oxidatant activity of DAP. Since DAP has been used for the treatment of coagulation disorder and rheumatoid arthritis for long time with a safety profile, DAP will be a promising agent for the treatment of stroke.