Luteolin suppresses inflammation-associated gene expression by blocking NF-kappaB and AP-1 activation pathway in mouse alveolar macrophages

Anti-inflammatory effect of lavender (Lavandula angustifolia Mill.) essential oil prepared during different plant phenophases on THP-1 macrophages

BACKGROUND

Pseudomonas aeruginosa is the most common Gram-negative bacterium associated with nosocomial respiratory infections. Lavender essential oil is mainly used in aromatherapy, but it has several pharmacological and therapeutic properties. Furthermore, it possesses antifungal and antibacterial activities. The anti-inflammatory activity of essential oils may depend on the composition and the ratio of the compounds. The constitution of the essential oils extracted from the different stages of flowering period varies, which makes it plausible that the collection time of the flowers influences the anti-inflammatory effects. Different types of essential oils reduce inflammation acting similarly by modulating the activity and action of the NFκB signalling pathway, which is the major regulator of the transcription of pro-inflammatory cytokines.

METHODS

Lavender essential oils were distilled from lavender plant cultivated in Hungary and the flowers were harvested at the beginning and at the end of flowering period. The experiments were carried out on THP-1 human monocyte/macrophage cell line as in vitro cell culture model for monitoring the effects of lavender essential oils and the main compound linalool on P. aeruginosa LPS stimulated inflammation. The mRNA and protein levels of four pro-inflammatory cytokines, IL-6, IL-1β, IL-8 and TNFα were determined by Real Time PCR and ELISA measurements. The effects of essential oils were compared to the response to two NFκB inhibitors, luteolin and ACHP.

RESULTS

Linalool and lavender essential oil extracted from plants at the beginning of flowering period were successful in decreasing pro-inflammatory cytokine production following LPS pretreatment. In case of IL-8 and IL-1β lavender oil showed stronger effect compared to linalool and both of them acted similarly to NFκB inhibitors. Pretreatments with linalool and lavender essential oil/beginning of flowering period prevented pro-inflammatory cytokine production compared to LPS treatment alone. Although lavender essential oil/end of flowering period decreased IL-6, IL-1β and IL-8 mRNA expression in case of LPS pretreatment, it was not capable to reduce cytokine secretion.

CONCLUSION

Based on our results it has been proven that lavender essential oil extracted at the beginning of flowering period is a potent inhibitor of the synthesis of four pro-inflammatory cytokines IL-6, IL-8, IL-β and TNFα of THP-1 cells. This supports the relevance of the collection of the lavender flowers from early blooming period for essential oil production and for the utilization as an anti-inflammatory treatment.

Ginsenoside Rb1 Mitigates Escherichia coli Lipopolysaccharide-Induced Endometritis through TLR4-Mediated NF-κB Pathway

Endometritis is the inflammatory response of the endometrial lining of the uterus and is associated with low conception rates, early embryonic mortality, and prolonged inter-calving intervals, and thus poses huge economic losses to the dairy industry worldwide. Ginsenoside Rb1 (GnRb1) is a natural compound obtained from the roots of Panax ginseng, having several pharmacological and biological properties. However, the anti-inflammatory properties of GnRb1 in lipopolysaccharide (LPS)-challenged endometritis through the TLR4-mediated NF-κB signaling pathway has not yet been researched. This study was planned to evaluate the mechanisms of how GnRb1 rescues LPS-induced endometritis. In the present research, histopathological findings revealed that GnRb1 ameliorated LPS-triggered uterine injury. The ELISA and RT-qPCR assay findings indicated that GnRb1 suppressed the expression level of pro-inflammatory molecules (TNF-α, IL-1β and IL-6) and boosted the level of anti-inflammatory (IL-10) cytokine. Furthermore, the molecular study suggested that GnRb1 attenuated TLR4-mediated NF-κB signaling. The results demonstrated the therapeutic efficacy of GnRb1 in the mouse model of LPS-triggered endometritis via the inhibition of the TLR4-associated NF-κB pathway. Taken together, this study provides a baseline for the protective effect of GnRb1 to treat endometritis in both humans and animals.

Flavonoids: Classification, Function, and Molecular Mechanisms Involved in Bone Remodelling

Flavonoids are polyphenolic compounds spotted in various fruits, vegetables, barks, tea plants, and stems and many more natural commodities. They have a multitude of applications through their anti-inflammatory, anti-oxidative, anti-carcinogenic properties, along with the ability to assist in the stimulation of bone formation. Bone, a rigid connective body tissue made up of cells embedded in a mineralised matrix is maintained by an assemblage of pathways assisting osteoblastogenesis and osteoclastogenesis. These have a significant impact on a plethora of bone diseases. The homeostasis between osteoblast and osteoclast formation decides the integrity and structure of the bone. The flavonoids discussed here are quercetin, kaempferol, icariin, myricetin, naringin, daidzein, luteolin, genistein, hesperidin, apigenin and several other flavonoids. The effects these flavonoids have on the mitogen activated protein kinase (MAPK), nuclear factor kappa β (NF-kβ), Wnt/β-catenin and bone morphogenetic protein 2/SMAD (BMP2/SMAD) signalling pathways, and apoptotic pathways lead to impacts on bone remodelling. In addition, these polyphenols regulate angiogenesis, decrease the levels of inflammatory cytokines and play a crucial role in scavenging reactive oxygen species (ROS). Considering these important effects of flavonoids, they may be regarded as a promising agent in treating bone-related ailments in the future.

Inhibitory effects of luteolin and its derivatives on osteoclast differentiation and differences in luteolin production by Capsicum annuum varieties

Luteolin, an abundant flavonoid in the leaves of Capsicum annuum, has antioxidant activity and is, thus, a key chemical for promoting plant residue utilization, especially for the development of healthcare products. We assessed the inhibitory effect of luteolin and its glycosides on osteoclastic differentiation in human cells and found that the differentiation was effectively inhibited at noncytotoxic concentrations. We also screened 47 varieties of C. annuum for the accumulation of luteolin and apigenin to determine the prevalence of luteolin in diverse cultivars and identify varieties with high and/or selective luteolin production. The glycosides of luteolin and apigenin were found in all the tested varieties, with luteolin predominant over apigenin in most varieties. The identification and characterization of highly productive varieties of C. annuum is expected to be beneficial for the effective development of useful luteolin-based products from plant residues.

Effects of Reducing the South and Reinforcing the North Method on Inflammatory Injury Induced by Hyperlipidemia

Inflammation is the pathophysiological basis of hyperlipidemia-related disease (HRD). Reducing the south and reinforcing the north method (RSRN) has a positive effect on HRD. However, the pharmacological mechanisms of RSRN are still unclear in the treatment of HRD. We obtained RSRN compounds from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) and identified potential targets of these compounds through target fishing based on the TCMSP databases. Next, we identified the HRD targets by using multiple databases. Then, the overlapping genes between the RSRN potential targets and the HRD targets were used to establish a protein-protein interaction (PPI) network, and we further analyzed their interactions and identified the major hub genes in this network. Subsequently, the Metascape database was utilized to conduct the enrichment of Gene Ontology biological processes (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. A total of 187 potential active components and 106 related core targets were obtained and identified overall. Then after the Metascape enrichment analysis, a total of 148 KEGG pathways were screened, which were mainly associated with AGE-RAGE signaling pathway, PI3K-Akt signaling pathway, TNF signaling pathway, and NF-kappa B signaling pathway. Furthermore, 34 hub genes, such as AKT1, NF-κBp65(RELA), IκBα(CHUK), MAPK8, and MAPK14, CCND1, were considered potential therapeutic targets. Furthermore, evaluations of protein levels of NF-κBp65, IκBα, TNF-α, IL-1 ß, and IL-6 were performed for experimental validation. RSRN can reduce the expression of NF-κBp65 protein, increase the level of IκBα protein, and reduce the protein levels of TNF-α, IL-1β, and IL-6 in ovariectomized rats. The results indicate that the mechanism of RSRN against inflammation may be related to AKT1, NF-κBp65, IκBα, MAPK8, and MAPK14, as well as TNF, NF-kappa B, PI3K-Akt signaling pathways.

Immunity boosting nutraceuticals: Current trends and challenges

The immune function of the human body is highly influenced by the dietary intake of certain nutrients and bioactive compounds present in foods. The preventive effects of these bioactive ingredients against various diseases have been well investigated. Functional foods are consumed across various diverse cultures, in some form or the other, which provide benefits greater than the basic nutritional needs. Novel functional foods are being developed using novel bioactive ingredients such as probiotics, polyunsaturated fatty acids, and various phytoconstituents, which have a range of immunomodulatory properties. Apart from immunomodulation, these ingredients also affect immunity by their antioxidant, antibacterial, and antiviral properties. The global pandemic of Severe Acute Respiratory Syndrome Coronavirus-2 has forced the scientific community to race against time to find a proper and effective drug or a vaccine. In this review, various non-pharmacological interventions using nutraceuticals and functional foods have been discussed. PRACTICAL APPLICATIONS: Despite a plethora of research being undertaken to understand the immunity boosting properties of the various bioactive present in food, the findings are not translating to nutraceutical products in the market. Immunity has proved to be one of the most important factors for the health and well-being of an individual, especially when the world has been under the grip of the novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2. The anti-inflammatory properties of various nutraceuticals can come out as potential inhibitors of the various inflammatory processes such as cytokine storms, usually being observed in COVID 19. This review gives an insight into how various nutraceuticals can help in the prevention of various diseases through different mechanisms. The lack of awareness and proper clinical trials pose a challenge to the nutraceutical industry. This review will help and encourage researchers to further design and develop various functional foods, which might help in building immunity.

Anti-Inflammatory Properties of Diet: Role in Healthy Aging

Inflammation is a physiological process involved in the defenses of the body and the repair of tissues. It is acutely activated by infections, trauma, toxins, or allergic reactions. However, if it becomes chronic, inflammation can end up stimulating the development of diseases such as cardiovascular disease, autoimmune disease, neurological disease, or cancer. Additionally, during aging, inflammation becomes increasingly more chronic. Furthermore, we found that certain foods, such as saturated fats, have pro-inflammatory activity. Taking this into account, in this review we have discussed different diets with possible anti-inflammatory activity, the commonly ingested components of each diet and their active compounds. In addition, we have proposed some dietary guidelines, as well as a list of compounds present in foods with anti-inflammatory activity, outlining how to combine them to achieve optimal anti-inflammatory effects. Therefore, we can conclude that the compounds in our diet with anti-inflammatory activity could help alleviate the inflammatory processes derived from diseases and unhealthy diets, and thereby promote healthy aging.

A Review on Antidiabetic Activity of Centaurea spp.: A New Approach for Developing Herbal Remedies

Objective

Diabetes mellitus (DM) is a long-life metabolic disorder, characterized by high blood glucose levels. The hyperglycemic condition generally leads to irreversible nerve injury and vascular damage. Among different types of diabetes, type 2 is more common and has spread all over the world. Although various therapeutic approaches have been developed to control type 2 DM, regulating blood glucose levels has still remained a controversial challenge for patients. Also, most prescription drugs cause different side effects, such as gastrointestinal disorders. Thus, developing novel and efficient antidiabetic agents possessing fewer adverse effects is in high demand.

Method

The literature was comprehensively surveyed via search engines such as Google Scholar, PubMed, and Scopus using appropriate keywords.

Results

Medicinal plants, both extracts and isolated active components, have played a significant role in controlling the blood glucose levels. Good-to-excellent results documented in the literature have made them a precious origin for developing and designing drugs and supplements against DM. Centaurea spp. have been traditionally used for controlling high blood glucose levels. Also, the antidiabetic properties of different species of Centaurea have been confirmed in recent studies through in vitro assays as well as in vivo experiments.

Conclusion

Potent results encouraged us to review their efficacy to open a new horizon for development of herbal antidiabetic agents.

Breast cancer cell line toxicity of a flavonoid isolated from Baccharis densiflora

Background

Flavonoids are compounds of interest in the search for new anti-cancer therapies. We have previously isolated the methoxyflavones 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone (8-methoxycirsilineol), 5,4′-dihydroxy-6,7,8-trimethoxyflavone (xanthomicrol), and 5,4,'3′-trihydroxy-6,7,8-trimethoxyflavone (sideritoflavone) from Baccharis densiflora. Herein, we investigate the toxicity of these methoxyflavones in human breast-derived cell line. Our main aim was to focus on the cancer stem cell (CSC) sub-population of JIMT-1 breast cancer cells.

Methods

Initially, dose response experiments yielding inhibitory concentration 50 (IC₅₀) values were performed using MCF-7, HCC1937, and JIMT-1 breast cancer, and the MCF-10A normal-like breast cell lines to get an understanding of toxic ranges. Due to a clear difference in the toxicity of the flavones, only sideritoflavone was selected for further studies using the JIMT-1 cell line. Effects on the CSC sub-population was investigated using flow cytometry-based methods. A wound healing assay and digital holographic microscopy were used to investigate effects on cell movement. A reporter assay was used to study effects on signal transduction pathways and Western blot for protein expression.

Results

The dose response data showed that 8-methoxycirsilineol was non-toxic at concentrations below 100 μM, that the IC₅₀ of xanthomicrol was between 50 and 100 μM, while sideritoflavone was highly toxic with a single digit μM IC₅₀ in all cell lines. Treatment of the JIMT-1 cells with 2 μM sideritoflavone did not selectively effect the CSC sub-population. Instead, sideritoflavone treatment inhibited the proliferation of both the non-CSC and the CSC sub-populations to the same extent. The inhibition of cell proliferation resulted in an accumulation of cells in the G₂ phase of the cell cycle and the treated cells showed an increased level of γ-H2A histone family member X indicating DNA double strand breaks. Analysis of the effect of sideritoflavone treatment on signal transduction pathways showed activation of the Wnt, Myc/Max, and transforming growth factor-β pathways. The level of p65/nuclear factor kappa-light-chain-enhancer of activated Β cells was increased in sideritoflavone-treated cells. Cell movement was decreased by sideritoflavone treatment.

Conclusions

Altogether our data show that the methoxyflavone sideritoflavone has favourable anti-cancer effects that may be exploited for development to be used in combination with CSC specific compounds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03349-4.

Improving Anti-Inflammatory Effect of Luteolin with Nano-Micelles in the Bacteria-Induced Lung Infection

The effective therapy for lung infectious diseases became more and more difficult since the severe antibiotic resistance of pathogenic microorganisms, it is urgent to develop new antimicrobial agents. Luteolin has been reported to play a crucial part in host immune responses. However, the clinical use of luteolin is impeded due to its hydrophobicity and low oral bioavailability. In this study, we formulated luteolin-loaded Methoxy poly(ethylene glycol)-poly(lactide) micelles (luteolin/MPEG-PLA), to improve the bioavailability of luteolin in lung infectious diseases. The results showed that luteolin/MPEG-PLA treatment could reduce the adhesion of Klebsiella pneumoniae (K. pneumoniae) to lung epithelial cells and enhance the germicidal ability of macrophages against K. pneumoniae compared to untreated group. Meanwhile, luteolin/MPEG-PLA showed stronger adhesion resistance of epithelial cells and germicidal ability of macrophages compared with free luteolin. In vivo study, luteolin/MPEG-PLA administration significantly promoted the clearance of bacteria and reduced inflammatory infiltration of lung tissue in K. pneumoniae induced lung infectious mice model. Further studies showed that treatment with luteolin/MPEG-PLA reduced the mRNA expression of LPS-induced inflammatory cytokines and chemokines in macrophages significantly. In general, luteolin/MPEG-PLA can enhance the anti-bacterial ability of lung epithelial cells and macrophages, and has a stronger therapeutic effect than free luteolin in bacterial-induced lung infection. Luteolin/MPEG-PLA may be an excellent potential drug for bacterial-induced lung infectious diseases treatment.

Bovine β-Lactoglobulin Covalent Modification by Flavonoids: Effect on the Allergenicity and Human Intestinal Microbiota

The present study aims to investigate the structure of covalent conjugates of bovine β-lactoglobulin (BLG) and flavonoids (luteolin, myricetin, and hyperoside), and their effect on the allergenicity and human intestinal microbiota. Covalent modification of amino acids in BLG by flavonoids was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and o-phthaldialdehyde assay. The secondary and conformational structures of BLG were changed by the covalent modification, which were determined by the circular dichroism, Fourier transform infrared spectroscopy, fluorescence spectroscopy, and UV spectroscopy. The enzyme-linked immunosorbent assay (ELISA) and cell experiments indicated that BLG covalent conjugates could reduce IgE/IgG binding capacities and suppress the allergy reactivity of RBL-2H3 cells, suggesting that the covalent modification modulated the balance of T cells. Meanwhile, covalent modification of BLG with these flavonoids can alter the diversity of human intestinal microbiota and the community abundance at phylum, family, and genus levels. The results revealed that covalent modification of BLG with flavonoids alters human intestinal microbiota, might result in the reduction of allergenicity, which could provide information for confirming the relationship between food allergy and the intestinal microbial ecosystem.

Luteolin alleviates ulcerative colitis through SHP-1/STAT3 pathway

BACKGROUND

Previous studies have demonstrated that Luteolin has a positive effect on epithelial barrier integrity by promoting the function of tight protein, however, little is known about the underline mechanism of Luteolin. In this study, we constructed Caco-2 cell monolayer to explore the effects and the regulation mechanism of Luteolin in intestinal epithelial barrier integrity.

METHODS

Caco-2 cells were co-treated with TNF-α, Interferon-γ (IFN-γ) and Luteolin for 24 h. Overexpression or knockdown of SHP-1 was applied to study the effects of protein phosphoserine phosphatase-1 (SHP-1) on epithelial barrier integrity. Cell viability was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Barrier function was detected by trans-epithelial electrical resistance (TEER) and FITC-dextran assay. The expression levels of SHP-1, phosphorylation signal transducer and activator of transcription 3 (p-STAT3), STAT3 and tight junction proteins were measured by qRT-PCR or western blot. In vivo model of ulcerative colitis was established to detect the function of Luteolin in ulcerative colitis.

RESULTS

We clarified that Luteolin protected intestinal epithelial barrier function of Caco-2 monolayers by increasing the resistance values and tight junction (TJ) protein expression. The expression of OCLN, CLDN1, and ZO1 was increased by Luteolin, while the expression of CLDN2 was decreased. Furthermore, Luteolin significantly alleviated the symptom of ulcerative colitis in DSS-induced mice. The in vitro cell model proved that overexpression of SHP-1 promotes the epithelial barrier function and knockdown of SHP-1 or STAT3 activation destroyed the protective effects of Luteolin on the expression of TJ proteins.

CONCLUSION

We found that the treatment of Luteolin promoted epithelial barrier function and Luteolin might preserve intestinal epithelial barrier function through suppression of STAT3 signaling pathway by SHP-1.

Luteolin inhibits NLRP3 inflammasome activation via blocking ASC oligomerization

The NLRP3 inflammasome is a caspase-1 containing multi-protein complex that controls the release of IL-1β and plays important roles in the innate immune response. Since NLRP3 inflammasome is implicated in the pathogenesis of a variety of diseases, it has become an increasingly interested target in developing therapies for multiple diseases. We reported the current study to determine how luteolin, a natural phenolic compound found in many vegetables and medicinal herbs, would modulate NLRP3 inflammasome in both the in vivo and in vitro settings. First, we found that a high-fat diet upregulated mRNA expression of NLRP3 inflammasome components Asc and Casp1 in adipose tissue of ovariectomized mice, which were greatly reduced by dietary supplementation with luteolin. Of note, Asc and Casp1 expression in adipose tissue correlated with mRNA levels of Adgre1 encoding F4/80, an established marker for mature macrophages. We also demonstrated that luteolin inhibited NLRP3 inflammasome-derived caspase-1 activation and IL-1β secretion in J774A.1 macrophages upon diverse stimuli including ATP, nigericin, or silica crystals. Luteolin inhibited the activation step of NLRP3 inflammasome by interfering with ASC oligomerization. Taken together, these findings suggest that luteolin supplementation may suppress NLRP3 induction and activation process and thus potentially would be protective against NLRP3-mediated inflammatory diseases.

Anti-inflammatory effect of luteolin is related to the changes in the gut microbiota and contributes to preventing the progression from simple steatosis to nonalcoholic steatohepatitis

Increasing intestinal barrier function is one of the basic methods to suppress inflammation in the progression from simple steatosis (SS) to nonalcoholic steatohepatitis (NASH). Luteolin exists widely in vegetables, fruits and natural herbs and has various biological activities, including benefits on nonalcoholic fatty liver disease (NAFLD). However, its regulatory effects on the gut microbiota and involvement in its biological activities remain to be investigated. We fed rats a high-fat diet containing 0.5% luteolin for 12 weeks and determined the effects of luteolin on lipid metabolism, inflammation, and the gut microbiota. Supplementation with luteolin for 12 weeks significantly reduced blood lipids and hepatic lipid levels and improved liver fat accumulation and inflammation. Moreover, supplementation with luteolin led to the significant enrichment of more than 10% of gut bacterial species, which contributed to increase the abundance of ZO-1, reduce intestinal permeability, reduce plasma lipopolysaccharide, and inhibit the TLR4/NF-κB pathway. In summary, the anti-inflammatory effect of luteolin might be related to changes in the gut microbiota and contribute to preventing the progression from SS to NASH. Our research provides new insights into the anti-inflammatory mechanism of luteolin and supports its use as a dietary supplement for NAFLD patients.

Anti-inflammatory evaluation of Scurrula ferruginea (jack) danser parasitizing on Tecoma stans (L.) H.B.K. in LPS/IFN-γ-induced RAW 264.7 macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Scurrula ferruginea (Jack) Danser (locally known as 'Dedalu' or 'dian nan ji sheng' in Malaysia and China) is a hemi-parasitic shrub that is widely used as herbal medicine to treat inflammation, rheumatism, and stroke. However, the scientific basis of its anti-inflammatory function and mechanism remain to be proven.

AIM OF THE STUDY

To evaluate the anti-inflammatory activity as well as the preliminary mechanism of S. ferruginea parasitizing on Tecoma stans.

MATERIALS AND METHODS

The anti-inflammatory capability of freeze-dried stem aqueous extract was assessed via inhibition of inflammatory cytokines interleukin- (IL-) 1β, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α) production in lipopolysaccharide (LPS) and interferon-γ (IFN-γ) stimulated RAW 264.7 macrophages. The underlying anti-inflammatory mechanism was deciphered through reverse transcriptase and real time quantitative polymerase chain reactions (RT-PCR and qPCR) for inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1β, and TNF-α mRNA expression.

RESULTS

The results exhibited that aqueous extract of freeze-dried S. ferruginea stem sample concentration-dependently inhibited IL-1β protein production along with the down regulation of iNOS and IL-1β mRNA expression. Moreover, it significantly suppressed the protein release of IL-6 and IL-10 in a concentration-dependent manner. However, it slightly reduced TNF-α at higher sample concentration (250 μg/mL) without affecting the mRNA expression levels of COX-2 and TNF-α.

CONCLUSIONS

This study suggests that S. ferruginea parasitizing on Tecoma stans exerted anti-inflammatory capability attributed to inhibition of iNOS and IL-1β mRNA expression, NO creation, IL-1β, IL-6, IL-10, and TNF-α protein production, indicating this plant might be a useful plant-derived candidate against inflammation.

Luteolin alleviates inflammation and modulates gut microbiota in ulcerative colitis rats

Ulcerative colitis (UC) is a chronic inflammatory bowel disease related to intestinal dysbiosis. Luteolin has been reported to reduce inflammation. However, it remains unclear whether luteolin ameliorates UC and regulates gut microbiota. In this study, we investigated the effects of luteolin on colonic structure and inflammation of dextran sulfate sodium (DSS)-induced rats using hematoxylin-eosin staining, immunohistochemistry and enzyme-linked immunosorbent assay and evaluated the effects of luteolin on gut microbiota using 16S rDNA sequencing. We found that luteolin treatment significantly reduced colonic damage, and inhibited colonic inflammation in UC rats, evidenced by the decreased levels of NF-κB, IL-17 and IL-23 in UC rats and the increased level of PPAR-γ. In addition, the 16S rDNA sequencing analysis revealed that luteolin treatment could alter diversity and composition of gut microbiota in UC rats. Lactobacillus, Bacteroides, Roseburia and Butyricicoccus were dominant genera in the luteolin group. Luteolin treatment reduced DSS-induced increased ratios of Lactobacillus and Prevotella_9. Furthermore, KEGG analysis revealed that gut microbiota was mainly related to DNA repair and recombination proteins, ribosome, purine metabolism, peptidases, and pyrimidine metabolism. In conclusion, our results revealed that luteolin could alleviate DSS-induced colitis in rats, and gut microbiota had the potential to serve as promising biomarkers for uncovering the mechanism by which luteolin improved UC.

Antioxidant and Anti-Inflammatory Potential of Polyphenols Contained in Mediterranean Diet in Obesity: Molecular Mechanisms

Nutrition transition can be defined as shifts in food habits, and it is characterized by high-fat (chiefly saturated animal fat), hypercaloric and salty food consumption at the expense of dietary fibers, minerals and vitamins. Western dietary patterns serve as a model for studying the impact of nutrition transition on civilization diseases, such as obesity, which is commonly associated with oxidative stress and inflammation. In fact, reactive oxygen species (ROS) overproduction can be associated with nuclear factor-κB (NF-κB)-mediated inflammation in obesity. NF-κB regulates gene expression of several oxidant-responsive adipokines including tumor necrosis factor-α (TNF-α). Moreover, AMP-activated protein kinase (AMPK), which plays a pivotal role in energy homeostasis and in modulation of metabolic inflammation, can be downregulated by IκB kinase (IKK)-dependent TNF-α activation. On the other hand, adherence to a Mediterranean-style diet is highly encouraged because of its healthy dietary pattern, which includes antioxidant nutraceuticals such as polyphenols. Indeed, hydroxycinnamic derivatives, quercetin, resveratrol, oleuropein and hydroxytyrosol, which are well known for their antioxidant and anti-inflammatory activities, exert anti-obesity proprieties. In this review, we highlight the impact of the most common polyphenols from Mediterranean foods on molecular mechanisms that mediate obesity-related oxidative stress and inflammation. Hence, we discuss the effects of these polyphenols on a number of signaling pathways. We note that Mediterranean diet (MedDiet) dietary polyphenols can de-regulate nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) and NF-κB-mediated oxidative stress, and metabolic inflammation. MedDiet polyphenols are also effective in upregulating downstream effectors of several proteins, chiefly AMPK.

Luteolin delays photoreceptor degeneration in a mouse model of retinitis pigmentosa

Luteolin is neuroprotective for retinal ganglion cells and retinal pigment epithelial cells after oxidative injury, whereby it can inhibit microglial neurotoxicity. Therefore, luteolin holds the potential to be useful for treatment of retinal diseases. The purpose of this study was to investigate whether luteolin exhibits neuroprotective effects on rod cells in rd10 mice, a slow photoreceptor-degenerative model of retinitis pigmentosa. Luteolin (100 mg/kg) intraperitoneally injected daily from postnatal day 14 (P14) to P25 significantly enhanced the visual performance and retinal light responses of rd10 mice at P25. Moreover, it increased the survival of photoreceptors and improved retinal structure. Mechanistically, luteolin treatment attenuated increases in reactive oxygen species, photoreceptor apoptosis, and reactive gliosis; increased mRNA levels of anti-inflammatory cytokines while lowering that of pro-inflammatory and chemoattractant cytokines; and lowered the ratio of phospho-JNK/JNK. Application of the JNK inhibitor SP600125 exerted a similar protective effect to luteolin, suggesting that luteolin delays photoreceptor degeneration and functional deterioration in rd10 mice through regulation of retinal oxidation and inflammation by inhibiting the JNK pathway. Therefore, luteolin may be useful as a supplementary treatment for retinitis pigmentosa. This study was approved by the Qualified Ethics Committee of Jinan University, China (approval No. IACUC-20181217-02) on December 17, 2018.

The upshot of Polyphenolic compounds on immunity amid COVID-19 pandemic and other emerging communicable diseases: An appraisal

Polyphenols are a large family of more than 10,000 naturally occurring compounds, which exert countless pharmacological, biological and physiological benefits for human health including several chronic diseases such as cancer, diabetes, cardiovascular, and neurological diseases. Their role in traditional medicine, such as the use of a wide range of remedial herbs (thyme, oregano, rosemary, sage, mint, basil), has been well and long known for treating common respiratory problems and cold infections. This review reports on the most highlighted polyphenolic compounds present in up to date literature and their specific antiviral perceptive properties that might enhance the body immunity facing COVID-19, and other viral infectious diseases. In fact, several studies and clinical trials increasingly proved the role of polyphenols in controlling numerous human pathogens including SARS and MERS, which are quite similar to COVID-19 through the enhancement of host immune response against viral infections by different biological mechanisms. Thus, polyphenols ought to be considered as a potential and valuable source for designing new drugs that could be used effectively in the combat against COVID-19 and other rigorous diseases.

Mechanistic study of attenuation of monosodium glutamate mixed high lipid diet induced systemic damage in rats by Coccinia grandis

In the context of failure of treatment for non alcoholic fatty liver disease (NAFLD)-mediated systemic damages, recognition of novel and successful characteristic drug to combat these anomalous situations is earnestly required. The present study is aimed to evaluate protective value of ethanol extract of Coccinia grandis leaves (EECGL), naturally occurring medicinal plant, on NAFLD-mediated systemic damage induced by high lipid diet along with monosodium glutamate (HM)-fed rats. Our study uncovered that EECGL significantly ameliorates HM-induced hyperlipidemia, increased lipogenesis and metabolic disturbances (via up regulation of PPAR-α and PPAR-γ), oxidative stress (via reducing the generation of reactive oxygen species and regulating the redox-homeostasis) and inflammatory response (via regulating the pro-inflammatory and anti-inflammatory factors with concomitant down regulation of NF-kB, iNOS, TNF-α and up regulation of eNOS). Furthermore, EECGL significantly inhibited HM-induced increased population of cells in sub G0/G1 phase, decreased Bcl2 expression and thereby loss of mitochondrial membrane potential with over expression of Bax, p53, p21, activation of caspase 3 and 9 indicated the apoptosis and suppression of cell survival. It is perhaps the first comprehensive study with a mechanistic approach which provides a strong unique strategy for the management of HM-induced systemic damage with effective dose of EECGL.

Polyphenols and Other Bioactive Compounds of Sideritis Plants and Their Potential Biological Activity

Due to the growing problem of obesity associated with type 2 diabetes and cardiovascular diseases, causes of obesity are extensively investigated. In addition to a high caloric diet and low physical activity, gut microbiota disturbance may have a potential impact on excessive weight gain. Some reports indicate differences in the composition of the intestinal microflora of obese people in comparison to lean. Bioactive compounds of natural origin with beneficial and multifaceted effects on the body are more frequently used in prevention and treatment of many metabolic diseases including obesity. Sideritis scardica is traditionally consumed as mountain tea in the Balkans to strengthen the body and improve mood. Many reports indicate a positive effect on digestive system, weight loss, and prevention of insulin resistance. Additionally, it exhibits antioxidant activity and anti-inflammatory effects. The positive effect of Sideritis scardica extracts on memory and general cognitive abilities is indicated as well. The multilevel positive effect on the body appears to originate from the abundant occurrence of phenolic compounds, especially phenolic acids in Sideritis scardica extracts. However, mechanisms underlying their action require careful discussion and further research. Therefore, the objective of this review is to summarize the available knowledge on the role and mechanism of action of biologically active compounds of Sideritis scardica and other related species from the genus Sideritis.

Anti-inflammatory effect of methoxyflavonoids from Chiliadenus montanus (Jasonia Montana) growing in Egypt

Chiliadenus montanus is a medicinal plant that grows in Sinai Peninsula in Egypt. Phytochemical investigation of C. montanus methanolic extract led to the isolation of five methoxy flavonoids; Chrysosplenol-D (1), 5,7,4'-trihydroxy- 3,3'-dimethoxy flavone (2), 5,7-dihydroxy -3,3',4'-trimethoxyflavone (3), Bonanzin (4), 3,5,6,7,4'-pentamethoxy flavone (5), a sesquiterpene, Cryptomeridiol (6) and stigmast-5,22-dien-3-O-β-D-glucopyranoside (7). The anti-inflammatory activity of compounds 2 and 5 was assessed in vitro on CaCo2 cells stimulated by lipopolysaccharide (LPS). Both compounds downregulated LPS-induced expression of inflammatory cytokines; tumor necrosis factor alpha (TNFα), interleukin 1β (IL1β), nuclear factor kappa B (NFκB), cyclooxygenase 1 (Cox1), cyclooxygenase 2 (Cox2), and 5-lipoxygenase (5Lox). In vivo, both compounds significantly decreased paw edema thickness in rats relative to carrageenan, showing better anti-inflammatory activity than celecoxib (36.98%) after 1 h (46.60% and 48.11%, respectively). An in silico study was performed, where both compounds were docked into the active site of the crystal structure of the human Cox2 enzyme.

Oxidative stress responsive transcription factors in cellular signalling transduction mechanisms

Oxidative stress results from the imbalances in the development of reactive oxygen species (ROS) and antioxidants defence system resulting in tissue injury. A key issue resulting in the modulation of ROS is that it alters hosts molecular, structural and functional properties which is accomplished via various signalling pathways which either activate or inhibit numerous transcription factors (TFs). Some of the regulators include Nuclear erythroid-2 related factors (Nrf-2), CCAAT/enhancer-binding protein delta (CEBPD), Activator Protein-1 (AP-1), Hypoxia-inducible factor 1(HIF-1), Nuclear factor κB (NF-κB), Specificity Protein-1 (SP-1) and Forkhead Box class O (FoxO) transcription factors. The expression of these transcription factors are dependent upon the stress signal and are sometimes interlinked. They are highly specific having their own regulation cellular events. Depending upon the transcription factors and better knowledge on the type of the oxidative stress help researchers develop safe, novel targets which can serve as efficient therapeutic targets for several disease conditions.

Adaptive immunoregulation of luteolin and chlorogenic acid in lipopolysaccharide-induced interleukin-10 expression

Objective

To investigate the mechanism of the adaptive effect of two compounds in Lonicerae japonica flos (LJF), luteolin (LUT) and chlorogenic acid (CGA), on the expression of interleukin (IL) IL-10 and IL-6.

Materials and Methods

RAW264.7 cells receiving lipopolysaccharide (LPS) were pretreated with CGA and LJF. The expression of pro-inflammatory cytokines and IL-10 was evaluated by reverse transcription-polymerase chain reaction. Moreover, the concentrations of IL-10 and IL-6 were measured by enzyme-linked immunosorbent assay in the culture medium obtained 24 h after LPS treatment. Nuclear extracts of RAW264.7 cells, pretreated with CGA or LUT and LPS, were prepared after 6 h, and C/EBPβ and C/EBPδ were measured by Western blotting. Nuclear factor-κB (NF-κB) activity was measured by electrophoretic mobility shift assay. The phosphorylated form of IκB, ERK1/2, p38, JNK, and IκB, ERK2, p38, or JNK were also measured by Western blotting.

Results

CGA enhanced the LPS-induced expression of IL-10 and IL-6, and increased NF-κB, Sp1, C/EBPβ and δ. The effect of CGA is interfered with Lut by suppressing the phosphorylation of IκB and p38, and NF-κB activity. In the event, IL-6 was suppressed and IL-10 was not influenced.

Conclusion

LUT and CGA, which are abundant in LJF that is one of the ingredients in Gingyo-san, have adaptive immunoregulative effect on the expression of IL-10.

Luteolin-7-O-Glucoside Inhibits Oral Cancer Cell Migration and Invasion by Regulating Matrix Metalloproteinase-2 Expression and Extracellular Signal-Regulated Kinase Pathway

Oral squamous cell carcinoma is the sixth most common type of cancer globally, which is associated with high rates of cancer-related deaths. Metastasis to distant organs is the main reason behind worst prognostic outcome of oral cancer. In the present study, we aimed at evaluating the effects of a natural plant flavonoid, luteolin-7-O-glucoside, on oral cancer cell migration and invasion. The study findings showed that in addition to preventing cell proliferation, luteolin-7-O-glucoside caused a significant reduction in oral cancer cell migration and invasion. Mechanistically, luteolin-7-O-glucoside caused a reduction in cancer metastasis by reducing p38 phosphorylation and downregulating matrix metalloproteinase (MMP)-2 expression. Using a p38 inhibitor, SB203580, we proved that luteolin-7-O-glucoside exerts anti-migratory effects by suppressing p38-mediated increased expression of MMP-2. This is the first study to demonstrate the luteolin-7-O-glucoside inhibits cell migration and invasion by regulating MMP-2 expression and extracellular signal-regulated kinase pathway in human oral cancer cell. The study identifies luteolin-7-O-glucoside as a potential anti-cancer candidate that can be utilized clinically for improving oral cancer prognosis.

Improvement of Testicular Steroidogenesis Using Flavonoids and Isoflavonoids for Prevention of Late-Onset Male Hypogonadism

Androgen production, being important for male fertility, is mainly accomplished by the Leydig cells from the interstitial compartment of the testis. Testosterone plays a critical role in testis development, normal masculinization, and the maintenance of spermatogenesis. Within seminiferous tubules, appropriate Sertoli cell function is highly dependent on testicular androgen levels and is essential to initiate and maintain spermatogenesis. During aging, testosterone production by the testicular Leydig cells declines from the 30s in humans at a rate of 1% per year. This review outlines the recent findings regarding the use of flavonoids and isoflavonoids to improve testosterone production, contributing to normal spermatogenesis and preventing age-related degenerative diseases associated with testosterone deficiency. With the cumulation of information on the actions of different flavonoids and isoflavonoids on steroidogenesis in Leydig cells, we can now draw conclusions regarding the structure-activity relationship on androgen production. Indeed, flavonoids having a 5,7-dihydroxychromen-4-one backbone tend to increase the expression of the steroidogenic acute regulatory protein (StAR), being critical for the entry of cholesterol into the mitochondria, leading to increased testosterone production from testis Leydig cells. Therefore, flavonoids and isoflavonoids such as chrysin, apigenin, luteolin, quercetin, and daidzein may be effective in delaying the initiation of late-onset hypogonadism associated with aging in males.

Comparative transcriptomic analyses of chlorogenic acid and luteolosides biosynthesis pathways at different flowering stages of diploid and tetraploid Lonicera japonica

The Flos Lonicerae Japonicae (FLJ), Lonicera japonica Thunb, belonging to the Caprifoliaceae family, is an economically important plant that is highly utilized in traditional Chinese medicine as well as in Japanese medicine. The flowers of these plants are rich in chlorogenic acid (CGA) and luteoloside. Our previous study revealed that tetraploid L. japonica has higher fresh/dry weight, phenolic acids and flavonoids contents than those of diploid plants. However, why tetraploid L. japonica can yield higher CGA and luteolosides than that in diploid and what is the difference in the molecular regulatory mechanism of these pathways between diploid and tetraploids remained unclear. Therefore, in the present study, we performed comprehensive transcriptome analyses of different flowering stages of diploid and tetraploid L. japonica. The CGA content of tetraploid was found higher than that of diploid at all the growth stages. While the luteoloside content of diploid was higher than that of tetraploid at S4 and S6 growth stages. We obtained a high-quality transcriptome assembly (N50 = 2,055 bp; Average length = 1,331 bp) compared to earlier studies. Differential expression analysis revealed that several important genes involving in plant hormone signal transduction, carbon metabolism, starch/sucrose metabolism and plant-pathogen interaction were upregulated in tetraploid compared with the diploid L. japonica, reflecting the higher adaptability and resistance of tetraploid species. Furthermore, by associating the phenotypic data and gene expression profiles, we were able to characterize the potential molecular regulatory mechanism of important biosynthetic pathways at different flowering stages. Overall, our work provides a foundation for further research on these important secondary metabolite pathways and their implications in traditional Chinese/Japanese medicine.

Omentin-1 attenuates lipopolysaccharide (LPS)-induced U937 macrophages activation by inhibiting the TLR4/MyD88/NF-κB signaling

Macrophages play a pivotal role in the defense response against harmful pathogens and stimuli by releasing various pro-inflammatory mediators. However, overproduction of pro-inflammatory mediators will do harm to the organism and cause inflammation-associated diseases. Omentin-1, which is a newly discovered adipokine, is specifically expressed in omental adipose tissue. Recent studies have found correlations between omentin-1 and insulin resistance, diabetes, obesity, inflammation, atherosclerosis, bone metabolism, and tumor cell proliferation. Some studies have shown that the association between omentin-1, insulin resistance, and inflammation might suggest that omentin-1 plays an important role in chronic inflammatory diseases. In this study, we found that omentin-1 inhibited LPS-induced expression of inflammatory mediators and pro-inflammatory cytokines in macrophages. Furthermore, omentin-1 inhibited activation of the NF-κB pathway by suppressing both nuclear p65 accumulation and transfected NFκB promoter activity. Importantly, omentin-1 increased nuclear translocation of Nrf2. Our findings demonstrate that omentin-1 exerts anti-inflammatory effects on LPS-induced macrophages and has potential implication in the treatment of inflammation-associated diseases.

Remarkable rutin-rich Hypericum capitatum extract exhibits anti-inflammatory effects on turpentine oil-induced inflammation in rats

BACKGROUND

Natural extracts with beneficial biological activities are nowadays of high interest, in various treatment or prophylaxis. Hypericum capitatum has been known for its curative effects for centuries and its extracts have become of interest due to their distinct activity among other Hypericaceae members. In this study, further light is aimed to be shed on the secondary-metabolites composition of H. capitatum extracts, using chromatographic techniques and Electron paramagnetic resonance profiles in alkaline medium. Considering that no previous works explored the anti-inflammatory activity of H. capitatum, here, an in vivo study is also designed in order to evaluate this property by assessing the impact of one of H. capitatum extracts in ameliorating turpentine oil-induced inflammation on rats and to quantify their blood antioxidants level.

METHODS

Chromatographic techniques and Electron paramagnetic resonance spectroscopy were used in order to describe the chemical profile in different parts of the plant. The in vivo study on turpentine-oil induced inflammation in rats included three doses of H. capitatum extract expressed in rutin concentration. Oxidative stress was measured using total oxidative status, total antioxidant capacity, oxidative stress index, 3-nitrotyrosine, nitric oxide, malondialdehyde, superoxide dismutase, catalase and the inflammatory response was evaluated by performing a complete blood cells count and C reactive protein.

RESULTS

The extract was remarkably rich in rutin; however, other polyphenolic-like minor components appeared important in explaining the observed biological properties. The tested extract prevents the increase of inflammation-induced white blood cell count, number of neutrophils, and serum nitric oxide, and did so in a dose-dependent manner, similarly to the positive control-diclofenac. In addition, the same extract appeared to be a good alternative to diclofenac to restore total oxidative status, thiobarbituric active reactive species, total proteins and C reactive proteins. Moreover, antioxidant enzymes such as catalase, superoxide dismutase and total serum thiol concentration were significantly increased by the tested extract.

CONCLUSIONS

Due to its powerful reservoir rich in rutin, H. capitatum extract depicted its in vivo antioxidant and anti-inflammatory effects indicating it to be a good alternative to conventional drugs for oxidative stress protection.

Additive anti-inflammation by a combination of conjugated linoleic acid and α-lipoic acid through molecular interaction between both compounds

Alpha lipoic acid (LA) and conjugated linoleic acid (CLA) have been well-documented on a variety of functional effects in health foods. The main purpose of this study was focused on the additive anti-inflammatory activity of the combination of LA and CLA in vitro. Raw 264.7 cells induced by lipopolysaccharide were treated with LA and CLA individually or in combination at a variety of concentration ranges. Co-treating 25 μM of LA and 25 μM of CLA significantly inhibited pro-inflammatory cytokines compared to the same concentration of single LA- or CLA-treated group. The molecular mechanism of anti-inflammation by a combination of these compounds was attributed to extracellular signal-regulated kinase-1 (ERK1) and peroxisome proliferator-activated receptor gamma (PPARγ). Also, the molecular interaction between both compounds was confirmed by NMR. Our findings suggested that the combination of CLA and LA showed potential additive effect on anti-inflammation through the molecular interaction of both compounds.

Therapeutic Efficacy of Palmitoylethanolamide and Its New Formulations in Synergy with Different Antioxidant Molecules Present in Diets

The use of a complete nutritional approach seems increasingly promising to combat chronic inflammation. The choice of healthy sources of carbohydrates, fats, and proteins, associated with regular physical activity and avoidance of smoking is essential to fight the war against chronic diseases. At the base of the analgesic, anti-inflammatory, or antioxidant action of the diets, there are numerous molecules, among which some of a lipidic nature very active in the inflammatory pathway. One class of molecules found in diets with anti-inflammatory actions are ALIAmides. Among all, one is particularly known for its ability to counteract the inflammatory cascade, the Palmitoylethanolamide (PEA). PEA is a molecular that is present in nature, in numerous foods, and is endogenously produced by our body, which acts as a balancer of inflammatory processes, also known as endocannabionoid-like. PEA is often used in the treatment of both acute and chronic inflammatory pathologies, either alone or in association with other molecules with properties, such as antioxidants or analgesics. This review aims to illustrate an overview of the different diets that are involved in the process of opposition to the inflammatory cascade, focusing on capacity of PEA and new formulations in synergy with other molecules.

Natural Plants Compounds as Modulators of Epithelial-to-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a self-regulated physiological process required for tissue repair that, in non-controled conditions may lead to fibrosis, angiogenesis, loss of normal organ function or cancer. Although several molecular pathways involved in EMT regulation have been described, this process does not have any specific treatment. This article introduces a systematic review of effective natural plant compounds and their extract that modulates the pathological EMT or its deleterious effects, through acting on different cellular signal transduction pathways both in vivo and in vitro. Thereby, cryptotanshinone, resveratrol, oxymatrine, ligustrazine, osthole, codonolactone, betanin, tannic acid, gentiopicroside, curcumin, genistein, paeoniflorin, gambogic acid and Cinnamomum cassia extracts inhibit EMT acting on transforming growth factor-β (TGF-β)/Smads signaling pathways. Gedunin, carnosol, celastrol, black rice anthocyanins, Duchesnea indica, cordycepin and Celastrus orbiculatus extract downregulate vimectin, fibronectin and N-cadherin. Sulforaphane, luteolin, celastrol, curcumin, arctigenin inhibit β-catenin signaling pathways. Salvianolic acid-A and plumbagin block oxidative stress, while honokiol, gallic acid, piperlongumine, brusatol and paeoniflorin inhibit EMT transcription factors such as SNAIL, TWIST and ZEB. Plectranthoic acid, resveratrol, genistein, baicalin, polyphyllin I, cairicoside E, luteolin, berberine, nimbolide, curcumin, withaferin-A, jatrophone, ginsenoside-Rb1, honokiol, parthenolide, phoyunnanin-E, epicatechin-3-gallate, gigantol, eupatolide, baicalin and baicalein and nitidine chloride inhibit EMT acting on other signaling pathways (SIRT1, p38 MAPK, NFAT1, SMAD, IL-6, STAT3, AQP5, notch 1, PI3K/Akt, Wnt/β-catenin, NF-κB, FAK/AKT, Hh). Despite the huge amount of preclinical data regarding EMT modulation by the natural compounds of plant, clinical translation is poor. Additionally, this review highlights some relevant examples of clinical trials using natural plant compounds to modulate EMT and its deleterious effects. Overall, this opens up new therapeutic alternatives in cancer, inflammatory and fibrosing diseases through the control of EMT process.

Novel extraction techniques and pharmaceutical activities of luteolin and its derivatives

Luteolin is a 3', 4', 5, 7 tetra hydroxyl flavonoid that exits in many plants, fruits, and vegetable. Many methods of extraction, isolation, and purification are being used, and therapeutic properties are being under discussion due to its valuable role in nutrition and human health. In this review, we have summarized conventional and novel extraction techniques from most recent research on luteolin, its derivatives, and its biological activities. Maceration, soxhlet, reflux, hydrodistillation, ultrasound-assisted extraction, microwave-assisted extraction, ultrasound microwave-assisted extraction, enzyme-assisted extraction, supercritical fluid extraction, and high-speed counter-current chromatography extraction techniques are being used for isolation and purification of these phytochemicals. The anti-inflammatory, anti-cancer, antioxidant, antiviral, heart protective, neurological impairments protection, anti-aging, and whiting properties have been discussed in this review. The literature suggests luteolin and its derivative has many promising health benefits and its therapeutic activity is strongly associated with isolating and purifying solvents and extraction techniques. PRACTICAL APPLICATIONS: This review aims to highlight the sources, novel extraction techniques, and pharmaceutical properties of luteolin. This review provides enough knowledge about how to get maximum extraction yield of luteolin using the novel extraction techniques. Because its therapeutic activity is strongly associated with isolating and purifying solvents and techniques.

The modulatory effects of luteolin on cyclic AMP/Ciliary neurotrophic factor signaling pathway in experimentally induced autoimmune encephalomyelitis

Multiple sclerosis (MS) is considered to be an autoimmune disorder of the central nervous system (CNS) manifested by chronic inflammation. Although its etiology is not completely understood, inflammation and apoptosis are known to be major players involved in its pathogenesis. Luteolin, the naturally occurring flavonoid, is known by strong antioxidant and anti-inflammatory properties, yet research studies about its therapeutic role in MS are still lacking. The study aimed to provide insight into effects of luteolin in experimental autoimmune encephalomyelitis (EAE) by monitoring inflammatory, apoptotic, and antioxidant biochemical parameters in addition to histological examination findings. The study included 45 adult female Wistar rats allocated to three equal groups: (a) group I: control group, (b) group II: EAE group, EAE was induced by single intradermal injection of 0.2 mL inoculum comprising 20-μg recombinant rat myelin oligodendrocyte glycoprotein (MOG), and (c) group III: luteolin-treated EAE group, luteolin was given in a dose of 10 mg/kg/day, i.p. All groups were subjected to assessment of brain ciliary neurotropic factor (CNTF) mRNA gene expression and measurement of cleaved caspase 3, nuclear factor kappa B (NF-κB), cyclic AMP (cAMP), and macrophage inflammatory protein 1 alpha (MIP-1α) by the ELISA technique, total antioxidant capacity (TAC) level is assessed spectrophotometrically. Compared with the EAE group, luteolin-treated EAE group showed upregulation of CNTF expression and significant increase in cAMP and TAC levels, while it showed significant decrease in cleaved caspase 3, NF-κB, and MIP-1α levels. Based on our data herein, luteolin may provide a promising preclinical therapeutic line in MS being anti-inflammatory, antiapoptotic, and neurotrophic agent. © 2019 IUBMB Life, 71(9):1401-1408, 2019.

Sea bass (Lateolabrax maculatus) accelerates wound healing: A transition from inflammation to proliferation

ETHNOPHARMACOLOGICAL RELEVANCE

Sea bass (Lateolabrax maculatus) has been used for dietary therapy practice for wound healing of puerperal or surgery patients in China. Traditional Chinese medicinal books also documented that sea bass can be used to manage inflammation-associated conditions such as wound, miscarriage and cough. Some studies also proved that dietary supplement with fish benefited for treating many inflammatory - associated conditions, such as cardiovascular disease, ulcerative colitis and hyperlipidemia. However, the studies on the pharmacological mechanisms of wound healing efficacy of sea bass remain lack of investigation.

AIM OF THE STUDY

The aim of this study is to investigate the molecular mechanisms of sea bass on wound healing efficacy. Establishing a further justification for clinical application of aqueous extract of sea bass (ASB) in treating wound healing.

MATERIALS AND METHODS

Transition from inflammation to proliferation phase treated as the critical step in wound repair which were investigated via in vitro and in vivo study. A series of inflammatory mediators associated with wound healing and proliferation effects of fibroblasts upon treatments were studied via Western blotting, enzyme-linked immunosorbent assay (ELISA), real time reverse transcription-polymerase chain reaction (RT-PCR) and scratch assay. The cutaneous wound model was applied on skin wound healing study to observe the healing process in C57BL/6 mice upon ASB treatments. Hematological parameters and tumor necrosis factor-α (TNF-α) secretions in serum were determined. Histopathological examinations were conducted by hematoxylin and eosin (H&E) staining and Masson staining. Immunofluorescence were performed to identify infiltrating neutrophils (MPO) and α-smooth muscle actin (α-SMA).

RESULTS

Results showed that ASB significantly reduced the production of inflammatory mediators cyclooxygenase-2 (COX-2), nitrite oxide (NO) production and TNF-α. The phosphorylation and nuclear protein levels of transcription factor nuclear factor-κB (NF-ĸB) in toll-like receptor 4 (TLR4) signaling were decreased by ASB treatment as well. Wound closure rate and cyclin D1 expression level of fibroblasts were significantly increased by ASB treatments. Moreover, cutaneous wound model in C57BL/6 mice presented many similarities in appearance to the process of wound healing.

CONCLUSIONS

The in vitro study demonstrated an inhibitory effect of ASB on the inflammatory mediators regulated by TLR4 signaling pathways, providing evidence that ASB treatment potentially accelerate the wound healing through migration and proliferation enhancement. Additionally, the in vivo study suggested that ASB treatment has a potential in accelerating the proliferation phase of wound healing via well-organized abundant collagen deposition, angiogenesis and re-epithelialization in wounds. The present findings can be treated as a pharmacological basis for the folk use of sea bass and further studies in biological and medical fields.

Ginsenoside Rb1 ameliorates Staphylococcus aureus-induced Acute Lung Injury through attenuating NF-κB and MAPK activation

Acute lung injury (ALI) is clinically characterized by excessive inflammation leading to acute respiratory distress syndrome (ARDS), having high morbidity and mortality both in human and animals. Ginsenoside Rb1 (Rb1) is a major primary bioactive component extracted by Panax ginseng, which has numerous pharmacological functions such as anti-cancer, anti-inflammatory, and antioxidant. However, the anti-inflammatory effects of Rb1 in Staphylococcus aureus (S. aureus)-induced ALI in mice have not been investigated. The aim of the current study was to determine the anti-inflammatory influence of Rb1 on S. aureus-induced ALI in mice, and to explore its possible underlying principle mechanisms in RAW 264.7 macrophage cells. The results of physical morphology, histopathological variation and wet-to-dry weight ratio of lungs revealed that Rb1 significantly attenuated S. aureus-induced lung injury. Furthermore, qPCR results displayed that Rb1 inhibited IL-1β, IL-6 and TNF-α production both in vivo and in vitro. The activation of Toll-like receptor 2 (TLR2) by S. aureus was inhibited by application of Rb1 as confirmed by results of immunofluorescence assay. The expression of NF-kB and MAPK signaling proteins revealed that Rb1 significantly attenuated the phosphorylation of p65, ERK, as well as JNK. Altogether, the results of this experiment presented that Rb1 has ability to protect S. aureus-induced ALI in mice by attenuating TLR-2-mediated NF-kB and MAPK signaling pathways. Consequently, Rb-1 might be a potential medicine in the treatment of S. aureus-induced lung inflammation.

Luteolin: A Natural Flavonoid Enhances the Survival of HUVECs against Oxidative Stress by Modulating AMPK/PKC Pathway

Oxidative stress has been implicated in the pathogenesis of atherosclerotic cardiovascular diseases. Dietary supplementation of anti-oxidants has been reported to have beneficial effects on the prevention of atherogenic diseases. Luteolin (a natural flavonoid) has been shown to possess antimutagenic, antitumorigenic, anti-oxidant and anti-inflammatory properties. However, the effects and underlying molecular mechanisms of luteolin on cardiovascular systems are poorly explored. Therefore, the aim of the present study was to test whether luteolin could protect against oxidative stress-induced endothelial cell injury and explore the underlying mechanisms. In this study, human umbilical vein endothelial cells (HUVECs) were pre-treated with luteolin followed by hydrogen peroxide induction (H₂O₂). Our results showed that luteolin protected against H₂O₂-induced oxidative stress and ameliorated ROS and superoxide generation. In addition, we found that luteolin treatment inhibited the H₂O₂-induced membrane assembly of NADPH oxidase subunits, which was further confirmed by specifically inhibiting NADPH oxidase using DPI treatment. Furthermore, pAMPK protein expression was enhanced and p-PKC isoforms were significantly down-regulated by luteolin treatment in a dose-dependent manner, and a similar effect was observed upon DPI treatment. However, co-treatment with the specific inhibitor of AMPK (Compound C) restored p-PKC levels suggesting the role of AMPK signaling in regulating p-PKC expression under oxidative stress condition in HUVECs. Finally, we confirmed using siRNAs and specific inhibitor and/or activator of AMPK (AICAR) that luteolin treatment induced AMPK is a key player and regulator of activated expression of PKC isoforms and thereby confers protection against H₂O₂-induced oxidative stress in HUVECs.

Celastrol attenuates renal injury in diabetic rats via MAPK/NF-κB pathway

The purpose of this study was to investigate the renal protective effect of celastrol on diabetic rats. Furthermore, the mechanism of its action was discussed whether it was related to MAPK/NF-κB signaling pathway. There were a total of 36 rats. Six rats were randomly chosen as the control group. The remaining 30 rats were given 1% streptozotocin intraperitoneal injection (50 mg/kg) and were randomly divided into five groups: the model control group, the low-dose celastrol group, the high-dose celastrol group, the Tripterygium wilfordii polyglycosides group, and the MAPK/NF-κB inhibitor group. After 4 weeks of continuous administration, 24-hr urine volume, urinary protein, blood urea nitrogen, and serum creatinine content were observed, and hematoxylin-eosin (HE) staining of the kidney and liver were evaluated. p38MAPK was designated by immunohistochemical method, and NF-κB p65 in renal tissue was detected by western blotting. Our results showed that celastrol could not only reduce contents of creatinine and urea nitrogen in blood but also reduce excretion of urinary protein in diabetic rats, improve renal pathological injury, and down-regulate the expression of p38MAPK and NF-κB p65. In conclusion, celastrol could protect kidney of diabetic rats by regulating the signal pathway of MAPK/NF-κB, inhibiting inflammation and delaying renal injury.

Protection against nonalcoholic steatohepatitis through targeting IL-18 and IL-1alpha by luteolin

BACKGROUND

The management of nonalcoholic steatohepatitis (NASH) is still a crosstalk so the current study was designed to evaluate the effect of different luteolin doses on an experimental model of NASH and to elucidate novel anti-inflammatory pathways underlying its effect.

METHODS

Adult male Wistar rats (200-220 g; n = 60) were used. Rats were fed a high carbohydrate/high fat diet (˜ 30% carbohydrate and 42% fat) daily for 12 weeks to induce NASH. Luteolin (10, 25, 50 or 100 mg/kg/day) was administered as a suspension (10% w/v in 0.9% NaCl) using an oral gavage. Histopathological changes (necrosis, inflammation and steatosis) were evaluated. Biomarkers for liver function, lipid peroxidation, extracellular matrix deposition and anti-oxidant activity were measured. Levels of IFN-γ, TNF-α and IL-1α and IL-18 were measured.

RESULTS

Obtained results showed ability of luteolin to reduce activity of ALT and AST and to decrease levels of bilirubin, hyaluronic acid and malondialdehyde significantly (p <  0.05). Also, luteolin showed an anti-oxidant activity as indicated by the significant (p <  0.05) increase in reduced glutathione. Finally, a significant (p <  0.05) decrease in IFN-γ, TNF-α, IL-1α and IL-18 levels was observed most notably in groups that received high doses of luteolin (50 and 100 mg/kg).

CONCLUSIONS

Luteolin can protect against non-alcoholic steatohepatitis through targeting the pro-inflammatory IL-1 and Il-18 pathways in addition to an antioxidant effect.

Cellular and Acellular Assays for Measuring Oxidative Stress Induced by Ambient and Laboratory-Generated Aerosols

INTRODUCTION

Many studies have established associations between exposure to air pollution, or atmospheric particulate matter (PM), and adverse health effects. An increasing array of studies have suggested oxidative stress as a possible mechanism by which PM-induced health effects arise, and as a result, many chemical and cellular assays have been developed to study PM-induced oxidant production. Although significant progress has been made in recent years, there are still many gaps in this area of research that have not been addressed. Many prior studies have focused on the aerosol of primary origin (e.g., the aerosol emitted from combustion engines) although the aerosol formed from the oxidation of volatile species, secondary organic aerosol (SOA), has been shown to be the predominant type of aerosol even in urban areas. Current SOA health studies are limited in number, and as such, the health effects of SOA are poorly characterized. Also, there is a lack of perspective in terms of the relative toxicities of different SOA systems. Additionally, although chemical assays have identified some SOA constituents associated with adverse health endpoints, the applicability of these results to cellular responses has not been well established.

SPECIFIC AIMS

The overall objective of this study was to better understand the oxidative properties of different types and components of PM mixtures (especially SOA) through systematic laboratory chamber experiments and ambient field studies. The study had four specific aims.

1 To develop a cellular assay optimized for measuring reactive oxygen and nitrogen species (ROS/RNS) production resulting from PM exposure and to identify a robust parameter that could represent ROS/RNS levels for comparison with different endpoints.

2 To identify ambient PM components associated with ROS/RNS production and evaluate whether results from chemical assays represented cellular responses in terms of ROS/RNS production.

3 To investigate and provide perspective on the relative toxicities of SOA formed from common biogenic and anthropogenic precursors under different conditions (e.g., humidity, nitrogen oxides [NOx], and redox-active metals) and identify bulk aerosol properties associated with cellular responses.

4 To investigate the effects of photochemical aging on aerosol toxicity.

METHODS

Ambient PM samples were collected from urban and rural sites in the greater Atlanta area as part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study between June 2012 and October 2013. The concentrations of water-soluble species (e.g., water-soluble organic carbon [WSOC], brown carbon [Br C], and metals) were characterized using a variety of instruments. Samples for this study were chosen to span the observed range of dithiothreitol (DTT) activities.

Laboratory studies were conducted in the Georgia Tech Environmental Chamber (GTEC) facility in order to generate SOA under well-controlled photooxidation conditions. Precursors of biogenic origin (isoprene, α-pinene, and β-caryophyllene) and anthropogenic origin (pentadecane, m-xylene, and naphthalene) were oxidized under various formation conditions (dry vs. humid, NOx, and ammonium sulfate vs. iron sulfate seed particles) to produce SOA of differing chemical composition and mass loading. For the naphthalene system, a series of experiments were conducted with different initial hydrocarbon concentrations to produce aerosols with various degree of oxidation. A suite of instruments was utilized to monitor gas- and particle-phase species. Bulk aerosol properties (e.g., O:C, H:C, and N:C ratios) were measured using a high-resolution time-of-flight aerosol mass spectrometer. Filter samples were collected for chemical oxidative potential and cellular measurements. For the naphthalene system, multiple filter samples were collected over the course of a single experiment to collect aerosols of different photochemical aging.

For all filter samples, chemical oxidative potentials were determined for water-soluble extracts using a semiautomated DTT assay system. Murine alveolar macrophages and neonatal rat ventricular myocytes were also exposed to PM samples extracted in cell culture medium to investigate cellular responses. ROS/RNS production was detected using the intracellular ROS/RNS probe, carboxy-2',7'-dichlorodihydrofluorescein diacetate (carboxy-H2DCFA), whereas cellular metabolic activity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Finally, cytokine production, that is, secreted levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were measured post-exposure using an enzyme-linked immunosorbent assay (ELISA). To identify PM constituents associated with oxidative properties, linear regressions between oxidative properties (cellular responses or DTT activity) and aerosol composition (metals, elemental ratios, etc.) were evaluated using Pearson's correlation coefficient, where the significance was determined using multiple imputation and evaluated using a 95% confidence interval.

RESULTS

We optimized several parameters for the ROS/RNS assay, including cell density (2 × 104 cells/well for macrophages and 3.33 × 104 cells/well for cardiomyocytes), probe concentration (10 µM), and sample incubation time (24 hours). Results from both ambient and laboratory-generated aerosols demonstrate that ROS/RNS production was highly dose-dependent and nonlinear with respect to PM dose. Of the dose-response metrics investigated in this study (maximum response, dose at which the response is 10% above the baseline [threshold], dose at which 50% of the response is attained [EC50], rate at which the maximum response is attained [Hill slope], and area under the dose-response curve [AUC]), we found that the AUC was the most robust parameter whose informativeness did not depend on dose range.

A positive, significant correlation was observed between ROS/RNS production as represented by AUC and chemical oxidative potential as measured by DTT for ambient samples collected in summer. Conversely, a relatively constant AUC was observed for ambient samples collected in winter regardless of the corresponding DTT activity. We also identified several PM constituents (WSOC, BrC, iron, and titanium) that were significantly correlated with AUC for summer samples. The strong correlation between organic species and ROS/RNS production highlights a need to understand the contribution of organic aerosols to PM-induced health effects. No significant correlations were observed for other ROS/RNS metrics or PM constituents, and no spatial trends were observed.

For laboratory-generated aerosol, precursor identity influenced oxidative potentials significantly, with isoprene and naphthalene SOA having the lowest and highest DTT activities, respectively. Both precursor identity and formation condition significantly influenced inflammatory responses induced by SOA exposure, and several response patterns were identified for SOA precursors whose photooxidation products share similar carbon-chain length and functionalities. The presence of iron sulfate seed particles did not have an apparent effect on oxidative potentials; however, a higher level of ROS/RNS production was observed for all SOA formed in the presence of iron sulfate compared with ammonium sulfate. We also identified a significant positive correlation between ROS/RNS production and average carbon oxidation state, a bulk aerosol property. It may therefore be possible to roughly estimate ROS/RNS production using this property, which is readily obtainable. This correlation may have significant implications as aerosols have an atmospheric lifetime of a week, during which average carbon oxidation state increases because of atmospheric photochemical aging. Our results suggest that aerosols might become more toxic as they age in the atmosphere. Finally, in the context of ambient samples, laboratory-generated SOA induced comparable or higher levels of ROS/RNS. Oxidative potentials for all laboratory SOA systems, with the exception of naphthalene (which was higher), were all comparable with oxidative potentials observed in ambient samples.

Protective effects of luteolin on injury induced inflammation through reduction of tissue uric acid and pro-inflammatory cytokines in rats

Background and aim

Luteolin belongs to flavone group of flavonoids, present in many plants with potent antioxidant, anti-inflammatory and anti-proliferative effects. The objective of present study was to investigate protective effect of luteolin on injury induced inflammation via Monosodium urate (MSU) crystals induced and Acetaminophen (AMP) induced liver injury in rats.

Experimental procedure

Protective effect of luteolin was observed by measurement of rat paw edema, lysosomal enzymes, antioxidants status and cytokine level. Measurement of uric acid level and neutrophil infiltration were done in AMP induced liver injury in rats. Luteolin was tested at 30 and 50 mg/kg doses and compare with colchicine.

Results and conclusion

Luteolin significantly decreases paw edema in dose dependent manner compare to control group in MSU crystal-induced rats. Luteolin (50 mg/kg) was showed significant decrease in serum level of oxidative and lysosomal enzymes, proinflammatory cytokines i.e. tumor necrosis factor (TNF)-α (39.28 ± 3.17), interleukin (IL)-1β (12.07 ± 1.24), and IL-6 (24.72 ± 2.52) in MSU crystal-induced rats. In AMP induced liver injury, tissue uric acid level and myeloperoxidase were decreased significantly after treatment with luteolin as well as N-acetylcysteine. Serum level of liver enzymes was significantly reduced after treatment with luteolin. Histological observation of ankle joints and liver was support to protective effect of luteolin at both doses. In conclusion, luteolin showed anti-inflammatory effect through restoration of cytokine level, lysosomal enzymes level and antioxidants status. The reduction of liver tissue uric acid content may be one of the mechanisms for protective effect of luteolin. It can contribute to reduce injury induced inflammation.

20-Hydroxy-3-Oxolupan-28-Oic Acid Attenuates Inflammatory Responses by Regulating PI3K⁻Akt and MAPKs Signaling Pathways in LPS-Stimulated RAW264.7 Macrophages

20-Hydroxy-3-oxolupan-28-oic acid (HOA), a lupane-type triterpene, was obtained from the leaves of Mahonia bealei, which is described in the Chinese Pharmacopeia as a remedy for inflammation and related diseases. The anti-inflammatory mechanisms of HOA, however, have not yet been fully elucidated. Therefore, the objective of this study was to characterize the molecular mechanisms of HOA in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. HOA suppressed the release of nitric oxide (NO), pro-inflammatory cytokine tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6) in LPS-stimulated RAW264.7 macrophages without affecting cell viability. Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) analysis indicated that HOA also suppressed the gene expression of inducible NO synthase (iNOS), TNF-α, and IL-6. Further analyses demonstrated that HOA inhibited the phosphorylation of upstream signaling molecules, including p85, PDK1, Akt, IκBα, ERK, and JNK, as well as the nuclear translocation of nuclear factor κB (NF-κB) p65. Interestingly, HOA had no effect on the LPS-induced nuclear translocation of activator protein 1 (AP-1). Taken together, these results suggest that HOA inhibits the production of cytokine by downregulating iNOS, TNF-α, and IL-6 gene expression via the downregulation of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs), and the inhibition of NF-κB activation. Our findings indicate that HOA could potentially be used as an anti-inflammatory agent for medical use.

The ethanol extract of honeysuckle stem modulates the innate immunity of Chinese mitten crab Eriocheir sinensis against Aeromonas hydrophila

Honeysuckle stem had been used as feed additives to modulate immunity in breeding industry, which was limited in the aquaculture field. In this study, the immunomodulation of honeysuckle stem ethanol extract (designed as HSE) on Chinese mitten crab Eriocheir sinensis was detected. The crabs fed with HSE diets for 30 days had higher level of the total haemocyte count (HTC), lysozyme activity and PO activity (P < 0.05), and had no obvious affect on the phagocytic activity, NO and TNF-α level. When challenged with Aeromonas hydrophila (1.0 × 10⁷ colony-forming units), HSE exhibited weak antibacterial activity against A. hydrophila and increased survival rate of crabs. The decreasing of THC and the increasing of TNF-α concentration, EsCaspase and EsLITAF mRNA expression level were all inhibited significantly by HSE treatment (P < 0.05), when the crabs were challenged by A. hydrophila. Moreover, the following immune parameters of crabs were enhanced by HSE treatment after A. hydrophila infection, including the rising of phagocytosis index and phagocytic rate of haemocyte, the rising of lysozyme, PO, NOS activities and nitric oxide concentration (P < 0.05). Therefore, it was concluded that HSE had great potential to develop into feed additive of crabs, which could enhance the innate immunity of Chinese mitten crabs E. sinensis effectively after A. hydrophila infection.