Anti-Inflammatory Effects of Psoralen Derivatives on RAW264.7 Cells via Regulation of the NF-κB and MAPK Signaling Pathways

Bergapten Ameliorates Psoriatic Skin Lesions and IL-17A-Induced Activation of the NF-κB Signaling Pathway via the Downregulation of CYP1B1

Bergapten (BP) is a plant-derived furocoumarin that has a wide range of pharmacological effects. BP serves as a candidate amplifier in phototherapy against skin inflammation, such as psoriasis and atopic dermatitis. However, the anti-inflammatory role of BP remains elusive. We utilized IL-17A-stimulated keratinocyte line and imiquimod-challenged BALB/c mice to imitate psoriasis-like inflammation. Inflammatory phenotypes were determined by expressions of inflammatory genes and cytokines, histopathological changes and activities of nuclear factor-κB (NF-κB) pathway. An RNA-seq analysis of rodent skin was performed to explore possible mechanism lying behind. SiRNAs and antagonist (TMS) against cytochrome P450 family 1 subfamily B member 1 (CYP1B1) were subsequently used to determine the role of CYP1B1 in psoriasis pathogenesis in vitro and in vivo. Overexpression of CYP1B1 with lentivirus further validate therapeutic effect of BP. BP significantly suppressed activation of the NF-κB pathway by inhibiting p65 phosphorylation and improved the inflammatory phenotype both in vitro and in vivo. We revealed the key role of CYP1B1 in regulating the activation of the NF-κB signaling pathway. Knock-down with siRNAs significantly reduce the expression of inflammatory genes and cytokines. An intraperitoneal injection of TMS partially remediated IMQ-induced inflammation, mainly in terms of skin thickness. Overexpression of Cyp1b1 led to increased expression of the CYP1B1 protein and rescued the therapeutic effect of BP in vitro. This study revealed that BP suppressed expression of Cyp1b1 in keratinocytes and inhibited the activation of NF-κB signaling pathway by blocking the phosphorylation of p65.

Mechanistic Insights into the Stimulatory Effect of Melanogenesis of 4-Methylcoumarin Derivatives in B16F10 Melanoma Cells

Vitiligo is a skin condition characterized by the loss of pigment, resulting in white patches on various parts of the body. It occurs when melanocytes, the cells that are responsible for producing skin pigment, are destroyed or stop functioning. This study aimed to investigate the melanogenic potential of various 4-methylcoumarin (4MC) derivatives, including 6-methoxy-4-methylcoumarin (6M-4MC), 7-methoxy-4-methylcoumarin (7M-4MC), 7-amino-4-methylcoumarin (7A-4MC), 6,7-dihydroxy-4-methylcoumarin (6,7DH-4MC), 7,8-dihydroxy-4-methylcoumarin (7,8DH-4MC), and 6,7-dimethoxy-4-methylcoumarin (6,7DM-4MC), in B16F10 melanoma cells. Our findings revealed that, while 4MC, 7A-4MC, 6,7DH-4MC, and 7,8DH-4MC did not exhibit any effect on melanin production, significant stimulation of melanogenesis was observed with 6M-4MC, 7M-4MC, and 6,7DM-4MC, with 6M-4MC demonstrating the most pronounced effect. 6M-4MC significantly stimulated melanin production and tyrosinase activity in a concentration-dependent manner in B16F10 cells. A Western blot analysis revealed that 6M-4MC increased the expression levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2). Further mechanistic studies showed that 6M-4MC inhibited extracellular signal-regulated kinase (ERK) and protein kinase B (AKT), which led to the upregulation of MITF and TRP proteins and subsequent activation of melanin synthesis. Additionally, 6M-4MC activated GSK3β phosphorylation, reduced β-catenin phosphorylation, and stimulated melanogenesis via the GSK3β/β-catenin pathway. Moreover, a primary skin irritation test was conducted on the upper backs of 32 healthy female volunteers to assess the potential irritation or sensitization from 6M-4MC when applied topically at concentrations of 50 µM and 100 µM. The test results showed no adverse effects on the skin. Collectively, these findings suggest that 6M-4MC may be a promising pigmentation stimulator for use in cosmetics and in the medical treatment of hypopigmentation disorders, particularly in the treatment of skin conditions such as vitiligo.

Therapeutic potential of natural coumarins in autoimmune diseases with underlying mechanisms

Autoimmune diseases encompass a wide range of disorders characterized by disturbed immunoregulation leading to the development of specific autoantibodies, which cause inflammation and multiple organ involvement. However, its pathogenesis remains unelucidated. Furthermore, the cumulative medical and economic burden of autoimmune diseases is on the rise, making these diseases a ubiquitous global phenomenon that is predicted to further increase in the coming decades. Coumarins, a class of aromatic natural products with benzene and alpha-pyrone as their basic structures, has good therapeutic effects on autoimmune diseases. In this review, we systematically highlighted the latest evidence on coumarins and autoimmune diseases data from clinical and animal studies. Coumarin acts on immune cells and cytokines and plays a role in the treatment of autoimmune diseases by regulating NF-κB, Keap1/Nrf2, MAPKs, JAK/STAT, Wnt/β-catenin, PI3K/AKT, Notch and TGF-β/Smad signaling pathways. This systematic review will provide insight into the interaction of coumarin and autoimmune diseases, and will lay a groundwork for the development of new drugs for autoimmune diseases.

Coumarins and flavones from Ficus erecta and their anti-inflammatory activity

ETHNOPHARMACOLOGICAL RELEVANCE

Ficus erecta, a traditional Chinese She Ethnomedicine, has been historically utilized to treat various inflammatory conditions such as arthritis, nephritis, and osteoporosis. However, the underlying mechanisms accounting for its anti-inflammatory activity, as well as its active components, largely remain elusive.

AIM OF THE STUDY

The purpose of this research was to investigate the chemical constituents of F. erecta that contribute to its anti-inflammatory effects.

MATERIALS AND METHODS

Coumarins and flavones were obtained from the 95% EtOH extract of F. erecta using virous column chromatography and reversed-phase semipreparative HPLC. The structures of the new compounds were elucidated by extensive analysis of spectroscopic methods, including HRESIMS, 1D and 2D NMR spectra, and CD experiments. Cultured macrophage RAW264.7 cells were utilized for the anti-inflammatory experiments. MTT cell viability assay, Griess reagent method, ELISA, and Western blot experiments were employed to evaluate the anti-inflammatory activity and investigate the related mechanism.

RESULTS

Four new (1-4) and eleven previously identified (5-16) coumarins, together with one new (17) and six known flavones (18-23) were isolated from the whole plant of F. erecta. Compounds 7 and 17 significantly reduced nitric oxide (NO) and prostaglandin E2 (PGE2) production without cytotoxic effects. Furthermore, compounds 7 and 17 reduced the production of proinflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in a concentration-dependent manner. Western blot analysis indicated that compounds 7 and 17 suppressed the expression of iNOS, COX-2, and p-IκBα in LPS-stimulated RAW264.7 macrophage cells.

CONCLUSION

The current phytochemical investigations revealed that coumarins and flavones represent the primary chemical constituents of F. erecta. Compounds 7 and 17 exhibit potent anti-inflammatory properties, linked with the inhibition of NF-κB activation by preventing the degradation of IκBα phosphorylation. These compounds may serve as promising candidates for treating or preventing certain inflammatory diseases.

Psoralen Isolated from the Roots of Dorstenia psilurus Welw. Modulate Th1/Th2 Cytokines and Inflammatory Enzymes in LPS-Stimulated RAW 264.7 Macrophages

Dorstenia psilurus is a widely used plant spice in traditional African medicine to treat pain-related conditions. However, the anti-inflammatory mechanisms underlying this activity and the main active ingredients of D. psilurus have not yet been fully characterized. This study aimed to isolate and identify the main active anti-inflammatory constituents of the D. psilurus extract and to investigate the underlying anti-inflammatory mechanisms in murine macrophages. Chromatographic techniques and spectroscopic data were used for compound isolation and structure elucidation. The Griess reagent method and the ferrous oxidation-xylenol orange assay were used to evaluate the inhibition of NO production and 15-lipoxygenase activity, respectively. Cyclooxygenase activity was assessed using the fluorometric COX activity assay kit, and Th1/Th2 cytokine measurement was performed using a flow cytometer. The results indicated that the extract and fractions of D. psilurus inhibit NO production and proliferation of RAW 264.7 macrophage cells. Bioguided fractionation led to the identification of psoralen, a furocoumarin, as the main bioactive anti-inflammatory compound. Psoralen inhibited NO production and 15-lipoxygenase activity and reduced pro-inflammatory Th1 cytokines (IFN-γ, TNF-α, and IL-2) while increasing the secretion of anti-inflammatory cytokines (IL-4, IL-6, and IL-10) in activated RAW 264.7 macrophage cells. The encouraging results obtained in this study suggest that psoralen-based multiple modulation strategies could be a useful approach to address the treatment of inflammatory diseases.

An ethanolic extract of Arctium lappa L. leaves ameliorates experimental atherosclerosis by modulating lipid metabolism and inflammatory responses through PI3K/Akt and NF-κB singnaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS), a lipid-induced inflammatory condition of the arteries, is a primary contributor to atherosclerotic cardiovascular diseases including stroke. Arctium lappa L. leaf (ALL), an edible and medicinal herb in China, has been documented and commonly used for treating stroke since the ancient times. However, the elucidations on its anti-AS effects and molecular mechanism remain insufficient.

AIM OF THE STUDY

To investigate the AS-ameliorating effects and the underlying mechanism of action of an ethanolic extract of leaves of Arctium lappa L. (ALLE).

MATERIALS AND METHODS

ALLE was reflux extracted using with 70% ethanol. An HPLC method was established to monitor the quality of ALLE. High fat diet (HFD) and vitamin D3-induced experimental AS in rats were used to determine the in vivo effects; and oxidized low-density lipoprotein-induced RAW264.7 macrophage foam cells were used for in vitro assays. Simvatatin was used as positive control. Biochemical assays were implemented to ascertain the secretions of lipids and pro-inflammatory mediators. Haematoxylin-eosin (H&E) and Oil red O stains were employed to assess histopathological alterations and lipid accumulation conditions, respectively. CCK-8 assays were used to measure cytotoxicity. Immunoblotting assay was conducted to measure protein levels.

RESULTS

ALLE treatment significantly ameliorated lipid deposition and histological abnormalities of aortas and livers in AS rats; improved the imbalances of serum lipids including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C); notably attenuated serum concentrations of inflammation-associated cytokines/molecules including TNF-α, IL-6, IL-1β, VCAM-1, ICAM-1and MMP-9. Mechanistic studies demonstrated that ALLE suppressed the phosphorylation/activation of PI3K, Akt and NF-κB in AS rat aortas and in cultured foam cells. Additionally, the PI3K agonist 740Y-P notably reversed the in vitro inhibitory effects of ALLE on lipid deposition, productions of TC, TNF-α and IL-6, and protein levels of molecules of PI3K/Akt and NF-κB singnaling pathways.

CONCLUSIONS

ALLE ameliorates HFD- and vitamin D3-induced experimental AS by modulating lipid metabolism and inflammatory responses, and underlying mechanisms involves inhibition of the PI3K/Akt and NF-κB singnaling pathways. The findings of this study provide scientific justifications for the traditional application of ALL in managing atherosclerotic diseases.

Bergaptol, a Major Furocoumarin in Citrus: Pharmacological Properties and Toxicity

Bergaptol (5-hydroxypsoralen or 5-hydroxyfuranocoumarin) is a naturally occurring furanocoumarin widely found in citrus fruits, which has multiple health benefits. Nonetheless, no specific review articles on bergaptol have been published. Compiling updated information on bergaptol is crucial in guiding future research direction and application. The present review focuses on the research evidence related to the pharmacological properties and toxicity of bergaptol. Bergaptol has anti-inflammatory, antioxidant, anti-cancer, anti-osteoporosis, anti-microbial, and anti-lipidemic effects. It can inhibit the activities of cytochrome P450s (CYP), especially CYP2C9 and CYP3A4, thereby affecting the metabolism and concentrations of some drugs and toxins. Compared with other coumarins, bergaptol has the least potency to inhibit CYP3A4 in cancer cells. Instead, it can suppress drug efflux transporters, such as P-glycoprotein, thereby overcoming chemotherapeutic drug resistance. Furthermore, bergaptol has antimicrobial effects with a high potential for inhibition of quorum sensing. In vivo, bergaptol can be retained in plasma for longer than other coumarins. Nevertheless, its toxicity has not been clearly reported. In vitro study suggests that, unlike most furocoumarins, bergaptol is not phototoxic or photomutagenic. Existing research on bergaptol has mostly been conducted in vitro. Further in vivo and clinical studies are warranted to identify the safe and effective doses of bergaptol for its multimodal application.

Discovery of antitussive material basis and mechanisms in Citri Sarcodactylis Fructus by coupling UHPLC-Q/Orbitrap HRMS combined spectrum-effect relationship and metabolomics analyses

Citri Sarcodactylis Fructus (CSF) is widely used as food raw material and traditional Chinese medicine. Fingerprints of different fractions of CSF were established for spectrum-effect relationship analysis, and the main compounds were identified by UHPLC Quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q/Orbitrap HRMS). The antitussive effect was evaluated using a classical mouse model of cough induced by ammonia water. One-way ANOVA was used to determine differences in efficacy. The potential active compounds were screened by spectrum-effect relationship with grey relational degree analysis (GRA), Pearson bivariate correlation analysis (Pearson's), and partial least squares analysis (PLS) analyses. Differential metabolites associated with cough in serum were screened and identified using orthogonal partial least squares-discriminant analysis, HMDB database, and UHPLC-Q/Orbitrap HRMS. Metabolic pathway analysis was performed using MetaboAnalyst 5.0. Results indicate that 70 % ethanol elution fraction (70 % EF) is the major active fraction, and 8 components were identified to possess antitussive effects. Metabolomic analysis showed that 19 metabolites are potential biomarkers related to cough, and 70 % EF can remarkable restore 13 of them to normal levels (P < 0.05). These biomarkers are mainly involved in glycerophospholipid metabolism and sphingolipid metabolism. This study aims to reveal the main pharmacodynamic active sites and potential active ingredients of CSF's antitussive effect. In addition, metabolomics was used to preliminarily elucidate the in-vivo regulatory mechanism of the antitussive effect of the 70 % EF of CSF.

Possible correlated signaling pathways with chronic urate nephropathy: A review

Hyperuricemia nephropathy, also known as gouty nephropathy, refers to renal damage induced by hyperuricemia caused by excessive production of serum uric acid or low excretion of uric acid. the persistence of symptoms will lead to changes in renal tubular phenotype and accelerate the progress of renal fibrosis. The existence and progressive aggravation of symptoms will bring a heavy burden to patients, their families and society, affect their quality of life and reduce their well-being. With the increase of reports on hyperuricemia nephropathy, the importance of related signal pathways in the pathogenesis of hyperuricemia nephropathy is becoming more and more obvious, but most studies are limited to the upper and lower mediating relationship between 1 or 2 signal pathways. The research on the comprehensiveness of signal pathways and the breadth of crosstalk between signal pathways is limited. By synthesizing the research results of signal pathways related to hyperuricemia nephropathy in recent years, this paper will explore the specific mechanism of hyperuricemia nephropathy, and provide new ideas and methods for the treatment of hyperuricemia nephropathy based on a variety of signal pathway crosstalk and personal prospects.

The Effects of 2'-Hydroxy-3,6'-Dimethoxychalcone on Melanogenesis and Inflammation

In this study, we demonstrated that 2'-hydroxy-3,6'-dimethoxychalcone (3,6'-DMC) alleviated α-MSH-induced melanogenesis and lipopolysaccharides (LPS)-induced inflammation in mouse B16F10 and RAW 264.7 cells. In vitro analysis results showed that the melanin content and intracellular tyrosinase activity were significantly decreased by 3,6'-DMC, without cytotoxicity, via decreases in tyrosinase and the tyrosinase-related protein 1 (TRP-1) and TRP-2 melanogenic proteins, as well as the downregulation of microphthalmia-associated transcription factor (MITF) expression through the upregulation of the phosphorylation of extracellular-signal-regulated kinase (ERK), phosphoinositide 3-kinase (PI3K)/Akt, and glycogen synthase kinase-3β (GSK-3β)/catenin, and downregulation of the phosphorylation of p38, c-Jun N-terminal kinase (JNK), and protein kinase A (PKA). Furthermore, we investigated the effect of 3,6'-DMC on macrophage RAW264.7 cells with LPS stimulation. 3,6'-DMC significantly inhibited LPS-stimulated nitric oxide production. 3,6'-DMC also suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 on the protein level. In addition, 3,6'-DMC decreased the production of the tumor necrosis factor-α and interleukin-6. Successively, our mechanistic studies revealed that 3,6'-DMC also suppressed the LPS-induced phosphorylation of the inhibitor of IκBα, p38MAPK, ERK, and JNK. The Western blot assay results showed that 3,6'-DMC suppresses LPS-induced p65 translocation from cytosol to the nucleus. Finally, the topical applicability of 3,6'-DMC was tested through primary skin irritation, and it was found that 3,6'-DMC, at 5 and 10 μM concentrations, did not cause any adverse effects. Therefore, 3,6'-DMC may provide a potential candidate for preventing and treating melanogenic and inflammatory skin diseases.

6-Methylcoumarin Promotes Melanogenesis through the PKA/CREB, MAPK, AKT/PI3K, and GSK3β/β-Catenin Signaling Pathways

We investigated the effects of four coumarin derivatives, namely, 6-methylcoumarin, 7-methylcoumarin, 4-hydroxy-6-methylcoumarin, and 4-hydroxy-7-methylcoumarin, which have similar structures on melanogenesis in a murine melanoma cell line from a C57BL/6J mouse called B16F10. Our results showed that only 6-methylcoumarin significantly increased the melanin synthesis in a concentration-dependent manner. In addition, the tyrosinase, TRP-1, TRP-2, and MITF protein levels were found to significantly increase in response to 6-methylcoumarin in a concentration-dependent manner. To elucidate the molecular mechanism whereby 6-methylcoumarin-induced melanogenesis influences the melanogenesis-related protein expression and melanogenesis-regulating protein activation, we further assessed the B16F10 cells. The inhibition of the ERK, Akt, and CREB phosphorylation, and conversely, the increased p38, JNK, and PKA phosphorylation activated the melanin synthesis via MITF upregulation, which ultimately led to increased melanin synthesis. Accordingly, 6-methylcoumarin increased the p38, JNK, and PKA phosphorylation in the B16F10 cells, whereas it decreased the phosphorylated ERK, Akt, and CREB expressions. In addition, the 6-methylcoumarin activated GSK3β and β-catenin phosphorylation and reduced the β-catenin protein level. These results suggest that 6-methylcoumarin stimulates melanogenesis through the GSK3β/β-catenin signal pathway, thereby affecting the pigmentation process. Finally, we tested the safety of 6-methylcoumarin for topical applications using a primary human skin irritation test on the normal skin of 31 healthy volunteers. We found that 6-methylcoumarin did not cause any adverse effects at concentrations of 125 and 250 μM. Our findings indicate that 6-methylcoumarin may be an effective pigmentation stimulator for use in cosmetics and the medical treatment of photoprotection and hypopigmentation disorders.

Xanthotoxol alleviates secondary brain injury after intracerebral hemorrhage by inhibiting microglia-mediated neuroinflammation and oxidative stress

BACKGROUND

Oxidative damage and inflammation are two critical mechanisms underlying secondary brain injury (SBI) following intracerebral hemorrhage (ICH). Xanthotoxol is reported to alleviate brain edema and inhibit inflammatory responses. Herein, we investigated the effects of xanthotoxol and its related mechanisms in SBI post-ICH.

METHODS

To explore the clinical effects of xanthotoxol an animal model of ICH was established. Neurological scores, survival rates and brain water content were measured. Inflammatory responses and oxidative damage in the peri-hemorrhagic areas were determined by measuring pro-inflammatory cytokines and oxidative related factors. The activation of the M1/M2 phenotype was detected by western blotting and immunofluorescence.

RESULTS

Xanthotoxol improved the neurological functions and reduced cerebral edema in ICH mice. Additionally, xanthotoxol inhibited microglia activation and promotes microglial phagocytosis. Simultaneously, xanthotoxol promoted the transformation of BV2 cells from M1 phenotype to M2 phenotype, and protected BV2 cells against hemin-induced inflammation and oxidative stress. Mechanistically, xanthotoxol inactivated the NF-κB p65 signaling pathway in the hemin-challenged BV2 cells.

CONCLUSION

Xanthotoxol ameliorates SBI post-ICH by suppressing microglia-mediated neuroinflammation and oxidative stress and enhancing microglial phagocytosis through inhibition of NF-κB signaling.

Acenocoumarol Exerts Anti-Inflammatory Activity via the Suppression of NF-κB and MAPK Pathways in RAW 264.7 Cells

The repurposing of already-approved drugs has emerged as an alternative strategy to rapidly identify effective, safe, and conveniently available new therapeutic indications against human diseases. The current study aimed to assess the repurposing of the anticoagulant drug acenocoumarol for the treatment of chronic inflammatory diseases (e.g., atopic dermatitis and psoriasis) and investigate the potential underlying mechanisms. For this purpose, we used murine macrophage RAW 264.7 as a model in experiments aimed at investigating the anti-inflammatory effects of acenocoumarol in inhibiting the production of pro-inflammatory mediators and cytokines. We demonstrate that acenocoumarol significantly decreases nitric oxide (NO), prostaglandin (PG)E₂, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β levels in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Acenocoumarol also inhibits the expression of NO synthase (iNOS) and cyclooxygenase (COX)-2, potentially explaining the acenocoumarol-induced decrease in NO and PGE₂ production. In addition, acenocoumarol inhibits the phosphorylation of mitogen-activated protein kinases (MAPKs), c-Jun N terminal kinase (JNK), p38 MAPK, and extracellular signal-regulated kinase (ERK), in addition to decreasing the subsequent nuclear translocation of nuclear factor κB (NF-κB). This indicates that acenocoumarol attenuates the macrophage secretion of TNF-α, IL-6, IL-1β, and NO, inducing iNOS and COX-2 expression via the inhibition of the NF-κB and MAPK signaling pathways. In conclusion, our results demonstrate that acenocoumarol can effectively attenuate the activation of macrophages, suggesting that acenocoumarol is a potential candidate for drug repurposing as an anti-inflammatory agent.

Imperatorin Positively Regulates Melanogenesis through Signaling Pathways Involving PKA/CREB, ERK, AKT, and GSK3β/β-Catenin

The present study investigated the melanogenic effects of imperatorin and isoimperatorin and the underlying mechanisms of imperatorin using a mouse melanoma B16F10 model. Interestingly, treatment with 25 μM of either imperatorin or isoimperatorin, despite their structural differences, did not produce differences in melanin content and intracellular tyrosinase activity. Imperatorin also activated the expression of melanogenic enzymes, such as tyrosinase (TYR) and tyrosinase-related proteins TYRP-1 and TYRP-2. Mechanistically, imperatorin increases melanin synthesis through the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA)/cAMP-responsive element-binding protein (CREB)-dependent upregulation of microphthalmia-associated transcription factor (MITF), which is a key transcription factor in melanogenesis. Furthermore, imperatorin exerted melanogenic effects by downregulating extracellular signal-regulated kinase (ERK) and upregulating phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthesis kinase-3β (GSK-3β). Moreover, imperatorin increased the content of β-catenin in the cell cytoplasm and nucleus by reducing the content of phosphorylated β-catenin (p-β-catenin). Finally, we tested the potential of imperatorin in topical application through primary human skin irritation tests. These tests were performed on the normal skin (upper back) of 31 volunteers to determine whether 25 or 50 µM of imperatorin had irritation or sensitization potential. During these tests, imperatorin did not induce any adverse reactions. Taken together, these findings suggest that the regulation of melanogenesis by imperatorin can be mediated by signaling pathways involving PKA/CREB, ERK, AKT, and GSK3β/β-catenin and that imperatorin could prevent the pathogenesis of pigmentation diseases when used as a topical agent.

Imperatorin Inhibits Proliferation, Migration, and Inflammation via Blocking the NF-κB and MAPK Pathways in Rheumatoid Fibroblast-like Synoviocytes

Rheumatoid arthritis (RA) is a chronic joint inflammatory disease associated with the aberrant activation of fibroblast-like synoviocytes (FLSs). Searching for natural compounds that may suppress the activation of FLSs has become a complementary approach for RA treatment. Here, we investigated the effects and mechanisms of imperatorin (IPT) on proliferation, migration, and inflammation in primary cultured arthritic FLSs. We found that IPT significantly suppressed TNFα-induced proliferation and migration of arthritic FLSs, but showed little effect on survival and apoptosis. In addition, IPT treatment significantly reduced the TNFα-induced expression of pro-inflammatory cytokines (IL-1β, TNFα, IL-6, and IL-8) in arthritic FLSs. Further mechanism studies suggested that IPT inhibited the activations of p38 and extracellular signal-regulated kinase (ERK). Also, IPT blocked the nuclear factor of κB (NF-κB) activation by suppressing the phosphorylation and degradation of IκBα, thereby preventing the translocation of p65. Collectively, our results demonstrated that IPT could inhibit the over-activated phenotypes of arthritic FLSs via the mitogen-activated protein kinase (MAPK) (p38 and ERK) and NF-κB pathways leading to the down-regulation of pro-inflammatory cytokines, which might be beneficial to the anti-proliferative and anti-migratory activities of FLS cells. These findings suggest that IPT has the potential to be developed as a novel agent for RA treatment.