Eupafolin, a skin whitening flavonoid isolated from Phyla nodiflora, downregulated melanogenesis: Role of MAPK and Akt pathways

ETHNOPHARMACOLOGICAL RELEVANCE

In hyperpigmentation disorders marked by melanin overproduction in the skin, including melisma and freckles, melanogenesis is caused by tyrosinase overexpression. Natural medicinal resources, like Phyla nodiflora, a traditional Chinese herbal medicine, have been used for a long time to management of dermatological conditions, such as skin inflammation and melanogenesis. Eupafolin, a functional flavonoid isolated from Phyla nodiflora, is an herbal tea constituent and possesses anti-inflammatory and anticancer activities. However, molecular mechanisms of eupafolin-mediated antimelanogenesis remain unknown. We thus focused on its antimelanogenesis effects in B16F10 mouse melanoma cells.

MATERIAL AND METHODS

B16F10 cells were treated with eupafolin (0.01, 0.1, 1, and 10μM) in a dose-escalation-dependent manner for the determination of melanin, tyrosinase activity and melanogenesis protein levels by ELISA or western blot analysis.

RESULTS

Eupafolin treatment significantly reduced cellular melanin content and tyrosinase activity in a dose-dependent manner (P<0.05), and no cytotoxic effects were observed. Eupafolin was associated with reduction in the levels of phospho-cAMP response element-binding protein and microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase synthesis and tyrosinase-related protein expression, leading to inhibit melanin production. In addition, eupafolin significantly induced the phosphorylation of ERK1/2 and p38 MAPK, whereas the decreased effect was observed in the phosphorylation of Akt. Moreover, inhibitors of these signals recovered or attenuated the inhibitory effects of eupafolin on melanogenesis.

CONCLUSIONS

Our results seem that inhibition of Akt and activation of phospho-ERK or p38 MAPK may lead to the suppression of melanogenesis in eupafolin-treated B16F10 mouse melanoma cells.

Eupafolin ameliorates COX-2 expression and PGE2 production in particulate pollutants-exposed human keratinocytes through ROS/MAPKs pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Eupafolin is a major bioactive compound derived from the methanolic extract of the medicinal herb Phyla nodiflora, which has been used in traditional Chinese medicine to treat various inflammatory diseases. Recently, particulate air pollutants have been shown to induce inflammation of the skin. In this study, we seek to determine whether eupafolin can inhibit the production of inflammatory mediators in a human skin keratinocyte cell line exposed to particulate air pollutants (particulate matter, PM), and determine the molecular mechanisms involved.

MATERIALS AND METHODS

Human keratinocyte HaCaT cells were treated with PM in the presence or absence of eupafolin. Cyclooxygenase-2 (COX-2) protein and gene expression levels were determined by Western blotting, RT-PCR and luciferase activity assay. Prostaglandin E2 (PGE2) production was evaluated by the enzyme immunoassay method. Generation of intracellular reactive oxygen species (ROS) was measured by the dichlorofluorescin (DCFH) oxidation assay, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was determined by a chemiluminescence assay. For in vivo studies, COX-2 expression in the skin of BALB/c nude mice was analyzed by immunohistochemistry.

RESULTS

Eupafolin inhibited PM-induced COX-2 protein and gene expression and PGE2 production in HaCaT cells. In addition, eupafolin suppressed PM-induced intracellular ROS generation, NADPH oxidase activity, MAPK (ERK, JNK and p38) activation and NK-κB activation. In vivo studies showed that topical treatment with eupafolin inhibited COX-2 expression in the epidermal keratinocytes of PM-treated mice.

CONCLUSIONS

Eupafolin exerts anti-inflammatory and antioxidant effects on skin keratinocytes exposed to particulate air pollutants, and may have potential use in the treatment or prevention of air pollutant-induced inflammatory skin diseases in the future.

Eupafolin inhibits PGE2 production and COX2 expression in LPS-stimulated human dermal fibroblasts by blocking JNK/AP-1 and Nox2/p47(phox) pathway

Eupafolin, a major active component found in the methanol extracts of Phyla nodiflora, has been used to treat inflammation of skin. We examined its effects on cyclooxygenase-2 (COX-2) expression in LPS-treated human dermal fibroblasts. Lipopolysaccharide (LPS) significantly increased prostaglandin-E2 (PGE2) production associated with increased COX-2 expression in Hs68 cells. This effect was blocked by eupafolin, TLR-4 antibody, antioxidants (APO and NAC), as well as inhibitors, including U0126 (ERK1/2), SB202190 (p38), SP600125 (JNK1/2), and Tanshinone IIA (AP-1). In gene regulation level, qPCR and promoter assays revealed that COX-2 expression was attenuated by eupafolin. In addition, eupafolin also ameliorated LPS-induced p47 phox activation and decreased reactive oxygen species (ROS) generation and NADPH oxidase (Nox) activity. Moreover, pretreatment with eupafolin and APO led to reduced LPS-induced phosphorylation of ERK1/2, JNK, and p38. Further, eupafolin attenuated LPS-induced increase in AP-1 transcription factor binding activity as well as the increase in the phosphorylation of c-Jun and c-Fos. In vivo studies have shown that in dermal fibroblasts of LPS treated mice, eupafolin exerted anti-inflammation effects by decreasing COX-2 protein levels. Our results reveal a novel mechanism for anti-inflammatory and anti-oxidative effects of eupafolin that involved inhibition of LPS-induced ROS generation, suppression of MAPK phosphorylation, diminished DNA binding activity of AP-1 and attenuated COX-2 expression leading to reduced production of prostaglandin E2 (PGE2). Our results demonstrate that eupafolin may be used to treat inflammatory responses associated with dermatologic diseases.

The protective effect of eupafolin against TNF-α-induced lung inflammation via the reduction of intercellular cell adhesion molecule-1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Eupafolin, a major bioactive compound found in Phyla nodiflora, has the anti-inflammatory property. Upregulation of cell adhesion molecules in the lung airway epithelium is associated with the epithelium-leukocyte interaction and plays a critical role in the pathogenesis of lung airway inflammatory disorders. To investigate the effects of eupafolin on tumor necrosis factor-α (TNF-α)-induced intercellular cell adhesion molecule-1 (ICAM-1) expression in A549 human lung airway epithelial cells and the underlying mechanisms.

MATERIALS AND METHODS

The effect of eupafolin on ICAM-1 expression in A549 cells were examined by Western blotting and immunofluorescent staining. The mice were injected intraperitoneally with or without eupafolin and then were left untreated or were injected intratracheally with TNF-α. To detect the effect of eupafolin on ICAM-1 expression, the lung tissues were also examined by Western blotting and immunohistochemical staining.

RESULTS

Eupafolin pretreatment reduced the TNF-α-induced ICAM-1 expression and also the ERK1/2, JNK, p38, and AKT/PI3K phosphorylation. However, the increase in ICAM-1 expression with TNF-α treatment was unaffected by p38 and PI3K inhibitors. Eupafolin decreased the TNF-α-induced NF-κB p65 activation and its nuclear translocation. Furthermore, eupafolin reduced ICAM-1 expression in the lung tissues of TNF-α-treated mice.

CONCLUSIONS

Eupafolin exerts its anti-inflammatory activity by suppressing the TNF-α-induced ICAM-1 expression and subsequent monocyte adhesion via AKT/ERK1/2/JNK phosphorylation and nuclear translocation of NF-κB p65. These results suggest that eupafolin may represent a novel therapeutic agent targeting epithelial activation in lung inflammation.

Eupafolin Exhibits Potent Anti-Angiogenic and Antitumor Activity in Hepatocellular Carcinoma

Eupafolin is a flavonoid extracted from the common sage herb which has been used in China as traditional medicine. Previous studies had reported that eupafolin had antioxidative, anti-inflammatory and antitumor effects. However, the function and the mechanism of eupafolin to exert its antitumor activity, especially its effect on tumor angiogenesis, have not been elucidated. Herein, we showed that eupafolin significantly inhibited vascular endothelial growth factor (VEGF)-induced cell proliferation, migration and tube formation of human umbilical vascular endothelial cells (HUVECs) in a dose-dependent manner. Meanwhile, the new blood microvessels induced by VEGF in the matrigel plug were also substantially suppressed by eupafolin. The results of HCC xenograft experiments demonstrated eupafolin remarkably inhibited tumor growth and tumor angiogenesis in vivo, suggesting the antitumor activity exerted by eupafolin was closely correlated with its potency on tumor angiogenesis. Mechanism investigations revealed that eupafolin significantly blocked VEGF-induced activation of VEGFR2 in HUVEC cells as well as its downstream signaling pathway. In addition to the effect on endothelial cells, through inhibiting Akt activity in tumor cells, VEGF secretion in HepG2 was dramatically decreased after eupafolin treatment. Our study was the first to report the activity of eupafolin against tumor angiogenesis as well as the underlying mechanism by which eupafolin to exert its anti-angiogenic activity.

Eupafolin inhibits breast cancer cell proliferation and induces apoptosis by inhibiting the PI3K/Akt/mTOR pathway

Eupafolin is a flavonoid extracted from common sage. Previous studies have reported that Eupafolin has antioxidant, anti-inflammatory, and anti-tumor effects. However, its role in breast cancer remains unclear. The present study investigated the effects and underlying mechanism of action of Eupafolin using breast cancer cell lines. The effects of Eupafolin on breast cancer cell proliferation, migration, apoptosis and the cell cycle were determined. Cell viability and Transwell assays, reverse transcription-quantitative PCR, flow cytometry and western blot analysis were used in this study. The data showed that the proliferation, migration and invasion ability of EO771 cells treated with Eupafolin was significantly decreased, and the apoptosis rate was increased compared with that of the control. The protein levels of Bax and cleaved caspase 3 increased, whereas that of Bcl-2 decreased. In addition, Eupafolin treatment also caused the proliferation of breast cancer cells to be arrested at the G₀/G₁ phase. Furthermore, results from western blotting indicated that Eupafolin treatment decreased the protein levels of p-PI3K, p-Akt and p-mTOR. Taken together, the present findings demonstrate that Eupafolin has a significant inhibitory effect on the proliferation of EO771 cells, inhibits cell migration and invasion, and promotes cell apoptosis, thereby causing G₀/G₁ phase arrest, at least partially through the PI3K/Akt/mTOR signaling pathway. Therefore, the findings provide novel insights regarding the use of Eupafolin for the treatment of breast cancer.

Eupafolin ameliorates lipopolysaccharide-induced cardiomyocyte autophagy via PI3K/AKT/mTOR signaling pathway

Objective(s):

Eupafolin, a major active component of Eupatorium perfoliatum L., has anti-inflammatory and anti-oxidant properties. Lipopolysaccharide (LPS) is responsible for myocardial depression. A line of evidences revealed that LPS induces autophagy in cardiomyocytes injury. This study aims to evaluate the effects of eupafolin on LPS-induced cardiomyocyte autophagy.

Materials and Methods:

The effect of LPS on cell viability was examined by CCK-8. Autophagic protein 2 light chain 3 (LC3II), which was regulated by LPS and eupafolin, was examined using immunofluorescent staining. The expression levels of Beclin-1 and p62 were detected by western blotting. The effects of eupafolin on phosphatidylinositol-3-kinase/ protein kinase B/ mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway were also evaluated by western blotting and immunofluorescent staining.

Results:

Eupafolin pretreatment reduced the expression of LC3II and Beclin-1, whereas p62 was significant increased. In addition, eupafolin promoted expression of PI3K/AKT/mTOR signaling pathway and mTOR inhibitor rapamycin reversed the inhibitory effects on LPS-induced cardiomyocyte autophagy.

Conclusion:

Eupafolin exerts anti-autophagy activity via activation of PI3K/AKT/mTOR signaling pathway.

Eupafolin Suppresses P/Q-Type Ca2+ Channels to Inhibit Ca2+/ Calmodulin-Dependent Protein Kinase II and Glutamate Release at Rat Cerebrocortical Nerve Terminals

Eupafolin, a constituent of the aerial parts of Phyla nodiflora, has neuroprotective property. Because reducing the synaptic release of glutamate is crucial to achieving pharmacotherapeutic effects of neuroprotectants, we investigated the effect of eupafolin on glutamate release in rat cerebrocortical synaptosomes and explored the possible mechanism. We discovered that eupafolin depressed 4-aminopyridine (4-AP)-induced glutamate release, and this phenomenon was prevented in the absence of extracellular calcium. Eupafolin inhibition of glutamate release from synaptic vesicles was confirmed through measurement of the release of the fluorescent dye FM 1-43. Eupafolin decreased 4-AP-induced [Ca²⁺]_i elevation and had no effect on synaptosomal membrane potential. The inhibition of P/Q-type Ca²⁺ channels reduced the decrease in glutamate release that was caused by eupafolin, and docking data revealed that eupafolin interacted with P/Q-type Ca²⁺ channels. Additionally, the inhibition of calcium/calmodulin-dependent protein kinase II (CaMKII) prevented the effect of eupafolin on evoked glutamate release. Eupafolin also reduced the 4-AP-induced activation of CaMK II and the subsequent phosphorylation of synapsin I, which is the main presynaptic target of CaMKII. Therefore, eupafolin suppresses P/Q-type Ca²⁺ channels and thereby inhibits CaMKII/synapsin I pathways and the release of glutamate from rat cerebrocortical synaptosomes.

An innovative UPLC-MS/MS method for the quantitation and pharmacokinetics of eupafolin in rat plasma

In this experiment, a rapid and highly sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technology was established and validated for the quantitation and pharmacokinetic analysis of eupafolin in rat plasma, utilizing licochalcone B as internal standard (IS). After liquid-liquid extraction of the analyte samples by ethyl acetate, chromatographic separation was achieved using a UPLC HSS T3 column under gradient elution conditions, with the mobile phase consisting of acetonitrile and water (with 0.1 % formic acid). Eupafolin was quantified by multiple reaction monitoring (MRM) in electrospray positive-ion mode (ESI+), employing the mass transition m/z 315.2 → 300.3 for eupafolin and m/z 285.4 → 270.3 for IS. Eupafolin demonstrated excellent linear relationship (r > 0.99) over the concentration range of 1.25-1250 ng/mL, with the lower limit of quantification (LLOQ) of the UPLC-MS/MS assay determined as 1.25 ng/mL. Method validation followed the bioanalytical method validation criteria outlined by the FDA. The accuracy of eupafolin ranged from 86.7 % to 111.2 %, and the precision was less than 12 %. The matrix effect was observed at 92.8 %-98.6 %, while the recoveries exceeded 83.2 %. The established UPLC-MS/MS assay was successfully employed for the pharmacokinetic evaluation of eupafolin in rats. The half-lives (t1/2z) were determined to be 1.4 ± 0.4 h and 2.5 ± 1.4 h for intravenous and oral administration, respectively. Notably, the bioavailability of eupafolin was relatively low (8.3 %). The optimized UPLC-MS/MS technology showed highly sensitive, selective, and effective, rendering it suitable for the pharmacokinetics of eupafolin in preclinical practice.

Eupafolin hinders cross-talk between gastric cancer cells and cancer-associated fibroblasts by abrogating the IL18/IL18RAP signaling axis

BACKGROUND

Cancer-associated fibroblasts (CAFs) are involved in the progression of gastric cancer (GC) as a critical component of the tumor microenvironment (TME), yet specific interventions remain limited. Natural products hold a promising application prospect in the field of anti-tumor in view of their high activity and ease of binding with biological macromolecules. However, the role of natural products in modulating the cross-talk between CAFs and GC cells has not been fully investigated.

PURPOSE

The aim of this study was to identify a potential therapeutic target in CAFs and then screen for natural small molecule drugs with anti-tumor activity against this target.

METHODS

Integrating bioinformatics analysis of public databases and experimental validation of human samples and cell lines to identify a candidate target in CAFs. Molecular docking and biolayer interferometry technique were utilized for screening potential natural small molecule drugs. The efficacy and underlying mechanisms of the candidates were explored in vitro and in vivo through techniques such as lentiviral infection, cell spheroids culture, immunoprecipitation and cells-derived xenografts.

RESULTS

IL18 receptor accessory protein (IL18RAP) was found to be overexpressed in CAFs derived from GC tissues and facilitated the protumor function of CAFs on GC. Based on virtual screening and experimental validation, we identified a natural product, eupafolin, that interfered with IL18 signaling. Phenotyping studies confirmed that the proliferation, spheroids formation and tumorigenesis of GC cells facilitated by CAFs were greatly attenuated by eupafolin both in vitro and in vivo. Mechanistically, eupafolin impeded the formation of IL18 receptor (IL18R) complex by directly binding to IL18RAP, thus blocking IL18-mediated nuclear factor kappa B (NF-κB) activation and reduced the synthesis and secretion of IL6 in CAFs. As a consequence, it inactivated signal transducer and activator of transcription 3 (STAT3) in GC cells.

CONCLUSION

This study provides new evidence that IL18 signaling regulates the cross-talk between GC cells and CAFs. And it highlights a novel pharmacological role of eupafolin in inhibiting IL18 signaling, thereby curbing the development of GC via modulating CAFs.