Selected Extracts of Chinese Herbal Medicines: Their Effect on NF-κB, PPARα and PPARγ and the Respective Bioactive Compounds

Bamboo shoot dietary fiber alleviates gut microbiota dysbiosis and modulates liver fatty acid metabolism in mice with high-fat diet-induced obesity

Introduction

Obesity is a common nutritional disorder characterized by an excessive fat accumulation. In view of the critical role of gut microbiota in the development of obesity and metabolic diseases, novel dietary therapies have been developed to manage obesity by targeting the gut microbiome. In this study, we investigated anti-obesity effects of bamboo shoot dietary fiber (BSDF) and the potential mechanisms.

Methods

After 12 weeks of intervention with BSDF in high-fat mice, we detected obesity-related phenotypic indicators, and made transcriptomic analysis of liver tissue. Then we analyzed the changes of gut microbiota using 16S rRNA gene sequencing, explored the effect of BSDF on gut microbiota metabolites, and finally verified the importance of gut microbiota through antibiotic animal model.

Results and discussion

We found that BSDF was effective in reducing lipid accumulation in liver and adipose tissue and alleviating dyslipidemia and insulin resistance. Liver transcriptome analysis results showed that BSDF could improve lipid metabolism and liver injury by modulating peroxisome proliferator-activated receptor (PPAR) and fatty acid metabolic pathways. The 16S rRNA gene sequencing analysis of gut microbiota composition showed that BSDF significantly enriched beneficial bacteria such as Bifidobacterium, Akkermansia, Dubosiella, and Alloprevotella. Analysis of fecal metabolomics and gut microbiota metabolites revealed that BSDF increased the levels of several short-chain fatty acids and enriched bile acids, which may be important for improving lipid metabolism. Notably, the obesity-related metabolic disorders were abrogated after the abrogation of gut microbiota, suggesting that gut microbiota is a key factor in the beneficial effects of BSDF.

Conclusion

Our study suggests that BSDF as a prebiotic supplement has the potential to improve obesity by improving gut microbiota and modulating host PPAR and fatty acid metabolic pathways.

A comparison review of Hehuan flowers and Hehuan bark on the traditional applications, phytochemistry and pharmacological effects

ETHNOPHARMACOLOGICAL RELEVANCE

Albizia julibrissin Durazz is a well-known medicinal plant with the Chinese name Hehuan []. Hehuan bark and Hehuan flowers have long been recognized as traditional Chinese herbal medicine for treating anxiety, melancholy, insomnia, bruises, pulmonary abscess, fractures, carbuncle, amnesia, acute conjunctivitis, blurred vision, neonatal tetanus and stroke for thousands of years. They are recorded in Chinese Pharmacopoeia separately with different properties. Until now, new chemical constituents and pharmacological activities of Hehuan have been continuously studied and revealed.

THE AIM OF THE REVIEW

This review aims to provide a comprehensive summary of traditional applications, phytochemistry, pharmacology effects, and toxicology of Hehuan bark and Hehuan flowers, and give critical assessment and point out the promising direction for further research on Hehuan.

MATERIAL AND METHODS

A literature search was undertaken on Hehuan bark and Hehuan flowers by analyzing the information from scientific databases (SciFinder, Pubmed, Elsevier, Google Scholar, Web of Science, and Baidu Scholar). We also gathered the information of Hehuan from classic herbal literatures and conference papers on ethnopharmacology.

RESULTS

According to Chinese and English documents, the medicinal history of Hehuan in China can be traced back to ad 25. Meanwhile, its medicinal history as a kind of herbal medicine can also be found in other Asian countries. So far about 140 compounds have been isolated from Hehuan bark and Hehuan flowers, including triterpenoids, flavonoids, lignans, phenolic acids, alkaloids, etc. Among them, flavonoids mainly exist in Hehuan flowers, while Hehuan bark contains lignans and saponins. The composition differences between the barks and flowers of Hehuan account for the different effects and applications. Modern pharmacological studies have indicated that crude extracts and pure compounds of Hehuan flowers and Hehuan bark have multiple pharmacological activities, such as antineoplastic, immunomodulatory, anti-inflammatory, anxiolytic, antidepressant, metabolic regulation, anti-insomnia, neuroprotective, hepatoprotective, sedative, and anti-osteolytic activities.

CONCLUSIONS

Hehuan (Albizia julibrissin Durazz) is traditionally used to relieve depression, calm nerves, promote blood circulation and reduce swelling. Modern pharmacological studies have revealed that natural products from Hehuan bark and Hehuan flowers possess extensive pharmacological activities in treating cancer, enhancing immunity, regulating metabolism, improving mental state, etc. These properties make it great clinical application potential. Further research on natural pharmaceutical chemistry, pharmacology, toxicology, pharmacokinetics, and quality standards of Hehuan are still required to verify the efficacy and safety for future clinical applications.

Lophatherum gracile Bronghiart Suppresses Receptor Activator of Nuclear Factor Kappa-B Ligand-Stimulated Osteoclastogenesis and Prevents Ovariectomy-Induced Osteoporosis

Lophatherum gracile Bronghiart, used in traditional herbal medicine, has many biological properties including antiviral, antipyretic, antitumor, vasorelaxation, and neutrophilic inflammatory effects. However, its modulatory effects on bone metabolism have not been investigated previously. In this study, we examined the effects of a water extract of the leaves of L. gracile (WELG) on osteoclast differentiation and bone loss, and explored its underlying mechanisms. We found that WELG inhibits osteoclastogenesis by suppressing both receptor activator of nuclear factor-κB ligand (RANKL)-induced early activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB)- and RANKL-induced modulation of the positive and negative regulators of osteoclastogenesis in osteoclast precursors. In vivo study demonstrated that WELG protects against bone loss, weight gain, and fat accumulation without affecting uterine atrophy in an ovariectomy-induced postmenopausal osteoporosis mice model. In addition, photochemical analysis of WELG identified active constituents known to have bone-protective effects. Overall, the results of this study suggest that WELG can be a potential candidate for therapy and prevention of postmenopausal osteoporosis.

Herbal medicine for psychiatric disorders: Psychopharmacology and neuroscience-based nomenclature

Objectives: Herbs are frequently and concurrently used with prescribed drugs by patients worldwide. While clinical trials have found some herbs to be as useful as standard psychiatric drugs, most clinicians are unaware of their pharmacological mechanisms.Methods: We searched English language and other language literature with English abstracts listed in PubMed website, supplemented by additional through Google Scholar's free academic paper abstract website for publications on herbs, focussing on their clinical use in mental disorders, their neurobiology and their pharmacology.Results: A major reason for herbs remaining outside of mainstream psychiatry is that the terminology and concepts in herbal medicine are not familiar to psychiatrists in general. Many publications regarding the use of herbal medicine for psychiatric disorders are deficient in details regarding diagnosis, criteria for response and the neurobiology details compared with publications on standard psychotropic drugs. Nomenclature for herbal medicine is usually confusing and is not conducive to an easy understanding of their mode of action in psychiatric disorders.Conclusions: The recent neuroscience-based nomenclature (NbN) for psychotropics methodology would be a logical application to herbal medicine in facilitating a better understanding of the use of herbal medicine in psychiatry.

Ethnopharmacology-A Bibliometric Analysis of a Field of Research Meandering Between Medicine and Food Science?

Background: The research into bioactive natural products of medicinal plants has a long tradition, but ethnopharmacology as a well-defined field of research has a relatively short history, only dating back 50 years.

Aims: With the fast development of this field and its global importance especially in the fast developing economies of Asia it is timely to assess the most influential articles (as measured by citations) and to identify important drivers and research trends in this field.

Methods: Scopus was searched to identify relevant articles which were assessed by all three authors. The 100 most cited articles were identified and analyzed. Bibliometric software (VOSviewer) was utilized to supplement the analysis and to generate a term map that visualized the citation patterns of the 100 articles containing different terms.

Results: Forty-four of the 100 articles are reviews. On average, each of the 100 articles had 632 citations and since publication was cited 43 times annually. The four core journals were Journal of Ethnopharmacology (n = 17), Food Chemistry (n = 7), Life Sciences (n = 5), and Journal of Agricultural and Food Chemistry (n = 4). Anti-oxidant effects appeared to be a recurring and highly cited topic, whereas the links into drug discovery and neuropharmacology seemed to be less strong. Numerous medicinal plants and functional foods were the foci of research, and the foci shifted when comparing pre-2000 and post-2000 publications (with the later involving a broader spectrum of plants and foods and a wider range of biological effects). Contributions largely came from Asia, and also from the Americas, Africa, and Oceania, besides Europe.

Conclusion: We have identified and analyzed the 100 most-cited articles in ethnopharmacology. Within 50 years the field has gained a profile and while conventionally often linked to “traditional knowledge,” drug discovery and some areas of pharmacology, this analysis highlights its emerging importance in the context of disease prevention (food science), but also the development of research driven by the needs and interests of the fast developing economies most notably of Asia.

Pyranopyran-1,8-dione, an Active Compound from Vitices Fructus, Attenuates Cigarette-Smoke Induced Lung Inflammation in Mice

Previously, we isolated and identified pyranopyran-1,8-dione (PPY) from Viticis Fructus, as a bioactive compound possessing anti-inflammatory properties. The present study was aimed to evaluate the preventive benefit of PPY on cigarette-smoke (CS)-induced lung inflammation. C57BL/6 mice were exposed to CS for 2 weeks while PPY was administrated by oral injection 2 h before CS exposure. To validate the anti-inflammatory effects of PPY, the numbers of immune cells in the bronchoalveolar lavage fluid were counted. Proinflammatory cytokines (Tumor necrosis factor-α: TNF-α, IL-6) and keratinocyte chemokine (KC/CXCL1) were also measured. Histopathologic analysis and cellular profiles showed that inflammatory cell infiltrations were significantly decreased in peribronchial and perivascular area by PPY treatment. The alveolar destruction by CS was markedly ameliorated by PPY treatment. In addition, the TNF-α, IL-6, and KC levels were declined in the PPY groups. These observations suggest that PPY has a preventive potential for lung inflammatory diseases.

Fenofibrate inhibits tumour intravasation by several independent mechanisms in a 3-dimensional co-culture model

Lymph node metastasis of breast cancer is a clinical marker of poor prognosis. Yet, there exist no therapies targeting mechanisms of intravasation into lymphatics. Herein we report on an effect of the antidyslipidemic drug fenofibrate with vasoprotective activity, which attenuates breast cancer intravasation in vitro, and describe the potential mechanisms. To measure intravasation in a 3-dimensional co-culture model MDA-MB231 and MCF-7 breast cancer spheroids were placed on immortalised lymphendothelial cell (LEC) monolayers. This provokes the formation of circular chemorepellent induced defects (CCIDs) in the LEC barrier resembling entry ports for the intravasating tumour. Furthermore, the expression of adhesion molecules ICAM-1, CD31 and FAK was investigated in LECs by western blotting as well as cell-cell adhesion and NF-κB activity by respective assays. In MDA-MB231 cells the activity of CYP1A1 was measured by EROD assay. Fenofibrate inhibited CCID formation in the MDA-MB231/LEC- and MCF-7/LEC models and the activity of NF-κB, which in turn downregulated ICAM-1 in LECs and the adhesion of cancer cells to LECs. Furthermore, CD31 and the activity of FAK were inhibited. In MDA-MB231 cells, fenofibrate attenuated CYP1A1 activity. Combinations with other FDA-approved drugs, which reportedly inhibit different ion channels, attenuated CCID formation additively or synergistically. In summary, fenofibrate inhibited NF-κB and ICAM-1, and inactivated FAK, thereby attenuating tumour intravasation in vitro. A combination with other FDA-approved drugs further improved this effect. Our new concept may lead to a novel therapy for cancer patients.

Effects of Pinellia ternata (Thunb.) Berit. on the metabolomic profiles of placenta and amniotic fluid in pregnant rats

ETHNOPHARMACOLOGICAL RELEVANCE

Banxia (BX) is the root of Pinellia ternata (Thunb.) Berit. Its processed products, such as Jiang Banxia (JBX), have been clinically used in traditional Chinese medicine to treat vomiting, coughing, and inflammation. However, data for their safety for pregnant women are contradictory and confusing.

AIM OF THE STUDY

To further explore the safety of BX, an ultra-performance liquid chromatography coupled with liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) metabolomics approach was used to evaluate the metabolic perturbation in pregnant rats caused by BX and JBX.

MATERIALS AND METHODS

Placenta and amniotic fluid samples were collected from control Sprague-Dawley pregnant rats and exposed to BX suspension and JBX decoction (1.434g/kg/day). Samples were analyzed using LC-MS and GC-MS. The acquired MS data of above samples were further subjected to multivariate data analysis, and the significantly altered metabolites were identified. The associated pathways were constructed using MetaboAnalyst 3.0.

RESULTS

The weight and histopathology of the placenta from each group of rats had no definite difference. However, we found 20 differential endogenous metabolites that changed significantly in the placenta and amniotic fluid samples. The alterations of identified metabolites indicated a perturbation in glycerophospholipid metabolism, amino acid metabolism, and carbohydrate metabolism in pregnant rats exposed to BX and JBX.

CONCLUSION

In summary, this work suggested that oral administration of BX and JBX may induce disturbances in the intermediary metabolism in pregnant rats. This work contributes to further understanding the safety of BX and its processed products.

HDAC and NF-κB mediated cytotoxicity induced by novel N-Chloro β-lactams and benzisoxazole derivatives

Novel N-chloro â-Lactam and benzisoxazole derivatives were successfully synthesized with excellent yields (92-96%) under simple and mild reaction conditions. The β-lactams as a class acquired importance since the discovery of penicillin which contains β-lactam unit as an essential structural feature of its molecule, this interest continued unabated because of the therapeutic importance of β-lactam antibiotics. In silico studies of the compounds with cancer drug target enzymes showed the inhibition of HDAC (Histone Deacetylase) and NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) significantly. The compounds were then investigated for the inhibitory potential against the same enzymes in vitro. NF-κB inhibition was investigated by trans activation assay using HEK293/NF-κB-luc cells. Overall, the synthesized compounds induce the cancer cell toxicity by restraining the NF-κB transcription factor mediated by HDAC inhibition and thus the compounds act as dual inhibitors.

Polyyne hybrid compounds from Notopterygium incisum with peroxisome proliferator-activated receptor gamma agonistic effects

In the search for peroxisome proliferator-activated receptor gamma (PPARγ) active constituents from the roots and rhizomes of Notopterygium incisum, 11 new polyacetylene derivatives (1-11) were isolated. Their structures were elucidated by NMR and HRESIMS as new polyyne hybrid molecules of falcarindiol with sesquiterpenoid or phenylpropanoid moieties, named notoethers A-H (1-8) and notoincisols A-C (9-11), respectively. Notoincisol B (10) and notoincisol C (11) represent two new carbon skeletons. When tested for PPARγ activation in a luciferase reporter assay with HEK-293 cells, notoethers A-C (1-3), notoincisol A (9), and notoincisol B (10) showed promising agonistic activity (EC50 values of 1.7 to 2.3 μM). In addition, notoincisol A (9) exhibited inhibitory activity on NO production of stimulated RAW 264.7 macrophages.

Identification of plumericin as a potent new inhibitor of the NF-κB pathway with anti-inflammatory activity in vitro and in vivo

BACKGROUND AND PURPOSE

The transcription factor NF-κB orchestrates many pro-inflammatory signals and its inhibition is considered a promising strategy to combat inflammation. Here we report the characterization of the natural product plumericin as a highly potent inhibitor of the NF-κB pathway with a novel chemical scaffold, which was isolated via a bioactivity-guided approach, from extracts of Himatanthus sucuuba, an Amazonian plant traditionally used to treat inflammation-related disorders.

EXPERIMENTAL APPROACH

A NF-κB luciferase reporter gene assay was used to identify NF-κB pathway inhibitors from H. sucuuba extracts. Monitoring of TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin by flow cytometry was used to confirm NF-κB inhibition in endothelial cells, and thioglycollate-induced peritonitis in mice to confirm effects in vivo. Western blotting and transfection experiments were used to investigate the mechanism of action of plumericin.

KEY RESULTS

Plumericin inhibited NF-κB-mediated transactivation of a luciferase reporter gene (IC₅₀ 1 μM), abolished TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin in endothelial cells and suppressed thioglycollate-induced peritonitis in mice. Plumericin exerted its NF-κB pathway inhibitory effect by blocking IκB phosphorylation and degradation. Plumericin also inhibited NF-κB activation induced by transfection with the constitutively active catalytic subunit of the IκB kinase (IKK-β), suggesting IKK involvement in the inhibitory action of this natural product.

CONCLUSION AND IMPLICATIONS

Plumericin is a potent inhibitor of NF-κB pathways with a new chemical scaffold. It could be further explored as a novel anti-inflammatory lead compound.

Natural product agonists of peroxisome proliferator-activated receptor gamma (PPARγ): a review

Agonists of the nuclear receptor PPARγ are therapeutically used to combat hyperglycaemia associated with the metabolic syndrome and type 2 diabetes. In spite of being effective in normalization of blood glucose levels, the currently used PPARγ agonists from the thiazolidinedione type have serious side effects, making the discovery of novel ligands highly relevant.

Natural products have proven historically to be a promising pool of structures for drug discovery, and a significant research effort has recently been undertaken to explore the PPARγ-activating potential of a wide range of natural products originating from traditionally used medicinal plants or dietary sources. The majority of identified compounds are selective PPARγ modulators (SPPARMs), transactivating the expression of PPARγ-dependent reporter genes as partial agonists. Those natural PPARγ ligands have different binding modes to the receptor in comparison to the full thiazolidinedione agonists, and on some occasions activate in addition PPARα (e.g. genistein, biochanin A, sargaquinoic acid, sargahydroquinoic acid, resveratrol, amorphastilbol) or the PPARγ-dimer partner retinoid X receptor (RXR; e.g. the neolignans magnolol and honokiol). A number of in vivo studies suggest that some of the natural product activators of PPARγ (e.g. honokiol, amorfrutin 1, amorfrutin B, amorphastilbol) improve metabolic parameters in diabetic animal models, partly with reduced side effects in comparison to full thiazolidinedione agonists. The bioactivity pattern as well as the dietary use of several of the identified active compounds and plant extracts warrants future research regarding their therapeutic potential and the possibility to modulate PPARγ activation by dietary interventions or food supplements.

NF-κB inhibitors from Eurycoma longifolia

The roots of Eurycoma longifolia have been used in many countries of Southeast Asia to alleviate various diseases including malaria, dysentery, sexual insufficiency, and rheumatism. Although numerous studies have reported the pharmacological properties of E. longifolia, the mode of action of the anti-inflammatory activity has not been elucidated. Bioguided isolation of NF-κB inhibitors using an NF-κB-driven luciferase reporter gene assay led to the identification of a new quassinoid, eurycomalide C (1), together with 27 known compounds including 11 quassinoids (2-12), six alkaloids (13-18), two coumarins (19, 20), a squalene derivative (21), a triterpenoid (22), and six phenolic compounds (23-28) from the extract of E. longifolia. Evaluation of the biological activity revealed that C19-type and C20-type quassinoids, β-carboline, and canthin-6-one alkaloids are potent NF-κB inhibitors, with IC50 values in the low micromolar range, while C18-type quassinoids, phenolic compounds, coumarins, the squalene derivative, and the triterpenoid turned out to be inactive when tested at a concentration of 30 μM. Eurycomalactone (2), 14,15β-dihydroklaieanone (7), and 13,21-dehydroeurycomanone (10) were identified as potent NF-κB inhibitors with IC50 values of less than 1 μM.

A systematic review and meta-analysis of herbal medicine on chronic obstructive pulmonary diseases

Herbal medicine (HM) as an adjunct therapy has been shown to be promising for the chronic obstructive pulmonary disease (COPD). However, the role of herbs in COPD remains largely unexplored. In this present study, we conducted the systematic review to evaluate the efficacy of herbs in COPD. 176 clinical studies with reporting pulmonary function were retrieved from English and Chinese database. Commonly used herbs for acute exacerbations stage (AECOPD) and stable COPD stage (SCOPD) were identified. A meta-analysis conducted from 15 high quality studies (18 publications) showed that HM as an adjunct therapy had no significant improvement in pulmonary function (FEV1, FEV%, FVC, and FEV1/FVC) compared to conventional medicine. The efficacy of the adjunct HM on improving the arterial blood gas (PaCO2 and PaO2) for AECOPD and SCOPD remains inconclusive due to the heterogeneity among the studies. However, HM as an adjunct therapy improved clinical symptoms and quality of life (total score, activity score, and impact score of St. George's Respiratory Questionnaire). Studies with large-scale and double-blind randomized controlled trials are required to confirm the role of the adjunct HM in the management of COPD.

The effects of maekmoondong-tang on cockroach extract-induced allergic asthma

Maekmoondong-tang (MMDT) has long been used in Asian countries to treat respiratory diseases. However, the precise mechanisms underlying its effects on asthma are unknown. This study was conducted to evaluate the protective effects of MMDT in a cockroach allergen (CKA-)induced animal model of allergic asthma. After being challenged with CKA, the number of macrophages, eosinophils, neutrophils, lymphocytes, and total cells in the bronchoalveolar lavage fluid (BALF) was evaluated. The Th2 specific cytokines IL-4, IL-5, and IL-13 were also analyzed in BALF along with IgE levels in serum. For histological analysis, hematoxylin and eosin (H&E) staining, periodic acid-Schiff (PAS) staining, and immunohistochemical staining were performed. In addition, airway hyperresponsiveness was assessed by noninvasive plethysmography. The cellular profiles and histopathologic analysis demonstrated that peribronchial and perivascular inflammatory cell infiltrates were significantly decreased in the MMDT-treated groups compared with the cockroach extract-injected (CKA) groups. In addition, the IgE, IL-4, IL-5, and IL-13 levels were significantly decreased in the MMDT group. MMDT treatment also significantly attenuated airway hyperresponsiveness. These results demonstrated that MMDT significantly reduced the hallmark signs of asthma: elevated serum IgE, airway eosinophilia, airway remodeling, mucus hypersecretion, and airway hyperresponsiveness. The remarkable antiasthmatic effects of MMDT suggest its therapeutic potential in allergic asthma treatment.

Imbricaric acid and perlatolic acid: multi-targeting anti-inflammatory depsides from Cetrelia monachorum

In vitro screening of 17 Alpine lichen species for their inhibitory activity against 5-lipoxygenase, microsomal prostaglandin E₂ synthase-1 and nuclear factor kappa B revealed Cetrelia monachorum (Zahlbr.) W.L. Culb. & C.F. Culb. As conceivable source for novel anti-inflammatory compounds. Phytochemical investigation of the ethanolic crude extract resulted in the isolation and identification of 11 constituents, belonging to depsides and derivatives of orsellinic acid, olivetolic acid and olivetol. The two depsides imbricaric acid (4) and perlatolic acid (5) approved dual inhibitory activities on microsomal prostaglandin E₂ synthase-1 (IC₅₀ = 1.9 and 0.4 µM, resp.) and on 5-lipoxygenase tested in a cell-based assay (IC₅₀ = 5.3 and 1.8 µM, resp.) and on purified enzyme (IC₅₀ = 3.5 and 0.4 µM, resp.). Additionally, these two main constituents quantified in the extract with 15.22% (4) and 9.10% (5) showed significant inhibition of tumor necrosis factor alpha-induced nuclear factor kappa B activation in luciferase reporter cells with IC₅₀ values of 2.0 and 7.0 µM, respectively. In a murine in vivo model of inflammation, 5 impaired the inflammatory, thioglycollate-induced recruitment of leukocytes to the peritoneum.

The potent inhibitory effects on the three identified targets attest 4 and 5 a pronounced multi-target anti-inflammatory profile which warrants further investigation on their pharmacokinetics and in vivo efficacy.

Ethnopharmacological in vitro studies on Austria's folk medicine--an unexplored lore in vitro anti-inflammatory activities of 71 Austrian traditional herbal drugs

ETHNOPHARMACOLOGICAL RELEVANCE

In Austria, like in most Western countries, knowledge about traditional medicinal plants is becoming scarce. Searching the literature concerning Austria's ethnomedicine reveals its scant scientific exploration. Aiming to substantiate the potential of medicinal plants traditionally used in Austria, 63 plant species or genera with claimed anti-inflammatory properties listed in the VOLKSMED database were assessed for their in vitro anti-inflammatory activity.

MATERIAL AND METHODS

71 herbal drugs from 63 plant species or genera were extracted using solvents of varying polarities and subsequently depleted from the bulk constituents, chlorophylls and tannins to avoid possible interferences with the assays. The obtained 257 extracts were assessed for their in vitro anti-inflammatory activity. The expression of the inflammatory mediators E-selectin and interleukin-8 (IL-8), induced by the inflammatory stimuli tumor necrosis factor alpha (TNF-α) and the bacterial product lipopolysaccharide (LPS) was measured in endothelial cells. The potential of the extracts to activate the nuclear factors PPARα and PPARγ and to inhibit TNF-α-induced activation of the nuclear factor-kappa B (NF-κB) in HEK293 cells was determined by luciferase reporter gene assays.

RESULTS

In total, extracts from 67 of the 71 assessed herbal drugs revealed anti-inflammatory activity in the applied in vitro test systems. Thereby, 30 could downregulate E-selectin or IL-8 gene expression, 28 were strong activators of PPARα or PPARγ (inducing activation of more than 2-fold at a concentration of 10µg/mL) and 21 evoked a strong inhibition of NF-κB (inhibition of more than 80% at 10µg/mL).

CONCLUSION

Our research supports the efficacy of herbal drugs reported in Austrian folk medicine used for ailments associated with inflammatory processes. Hence, an ethnopharmacological screening approach is a useful tool for the discovery of new drug leads.

The Herbal Drug Melampyrum pratense L. (Koch): Isolation and Identification of Its Bioactive Compounds Targeting Mediators of Inflammation

Melampyrum pratense L. (Koch) is used in traditional Austrian medicine for the treatment of different inflammation-related conditions. In this work, we show that the extracts of M. pratense stimulated peroxisome proliferator-activated receptors- (PPARs-)α and -γ that are well recognized for their anti-inflammatory activities. Furthermore, the extract inhibited the activation of the proinflammatory transcription factor NF-κB and induction of its target genes interleukin-8 (IL-8) and E-selectin in vitro. Bioassay-guided fractionation identified several active flavonoids and iridoids including melampyroside and mussaenoside and the phenolic compound lunularin that were identified in this species for the first time. The flavonoids apigenin and luteolin were distinguished as the main components accountable for the anti-inflammatory properties. Apigenin and luteolin effectively inhibited tumor necrosis factor α (TNF-α)-induced NF-κB-mediated transactivation of a luciferase reporter gene. Furthermore, the two compounds dose-dependently reduced IL-8 and E-selectin protein expression after stimulation with lipopolysaccharide (LPS) or TNF-α in endothelial cells (ECs). The iridoids melampyroside and mussaenoside prevented the elevation of E-selectin in LPS-stimulated ECs. Lunularin was found to reduce the protein levels of the proinflammatory mediators E-selectin and IL-8 in ECs in response to LPS. These data validate the ethnomedical use of M. pratense for the treatment of inflammatory conditions and point to the constituents accountable for its anti-inflammatory activity.