Hydroxycinnamoyl derivatives and secoiridoid glycoside derivatives from Syringa vulgaris flowers and their effects on the pro-inflammatory responses of human neutrophils

Polyphenolic compounds of Phyllanthus amarus Schum & Thonn. (1827) and diabetes-related activity of an aqueous extract as affected by in vitro gastrointestinal digestion

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts of the aerial part of Phyllanthus amarus have been extensively used in several countries to cure diabetes. No data is available on the impact of gastrointestinal digestion of such crude extracts on their antidiabetic activity.

AIM OF THE STUDY

The aim of this study was to identify active fractions and compounds of fresh aerial parts of P. amarus extracted by an infusion method that are responsible for antidiabetic effects occurring at the level of glucose homeostasis.

MATERIALS AND METHODS

An aqueous extract was obtained by an infusion method and its polyphenolic composition was analysed by reverse phase UPLC-DAD-MS. The influence of in vitro gastrointestinal digestion was evaluated both on the chemical composition and on the antidiabetic effect of P. amarus infusion extract using glucose-6-phosphatase enzyme inhibition and stimulation of glucose uptake.

RESULTS

Analysis of the chemical composition of the crude extract revealed the presence of polysaccharides and various families of polyphenols such as phenolic acids, tannins, flavonoids and lignans. After simulated digestion, the total content of polyphenols decreased by about 95%. Caffeoylglucaric acid derivates and lignans exhibited strong stimulation of glucose uptake similar to metformin with an increase of 35.62 ± 6.14% and 34.74 ± 5.33% respectively. Moreover, corilagin, geraniin, the enriched polysaccharides fraction and the bioaccessible fraction showed strong anti-hyperglycemic activity with about 39-62% of glucose-6-phosphatase inhibition.

CONCLUSION

Caffeoylglucaric acid isomers, tannin acalyphidin M1 and lignan demethyleneniranthin were reported for the first time in the species. After in vitro gastroinstestinal digestion, the composition of the extract changed. The dialyzed fraction showed strong glucose-6-phosphatase inhibition.

Bio-Guided Isolation of Compounds from Fraxinus excelsior Leaves with Anti-Inflammatory Activity

Inflammation is the first physiological defence mechanism against external and internal stimuli. The prolonged or inappropriate response of the immune system may lead to the persistent inflammatory response that can potentially become a basis for chronic diseases e.g., asthma, type II diabetes or cancer. An important role in the alleviation of inflammatory processes, as an adjunct to traditional pharmacological therapy, is attributed to phytotherapy, especially to raw materials with a long tradition of use, e.g., ash leaves. Despite their long-term use in phytotherapy, the specific mechanisms of action have not been confirmed in a sufficient number of biological or clinical studies. The aim of the study is a detailed phytochemical analysis of infusion and its fractions, isolation of pure compounds from the leaves of Fraxinus excelsior and evaluation of their effect on the secretion of anti-inflammatory cytokines (TNF-α, IL-6) and IL-10 receptor expression in an in vitro model of monocyte/macrophage cells isolated from peripheral blood. Methods: Phytochemical analysis was carried out by the UHPLC-DAD-ESI-MS/MS method. Monocytes/macrophages were isolated from human peripheral blood using density gradient centrifugation on Pancoll. After 24 h incubation with tested fractions/subfractions and pure compounds, cells or their supernatants were studied, respectively, on IL-10 receptor expression by flow cytometry and IL-6, TNF-α, IL-1β secretion by the ELISA test. Results were presented with respect to Lipopolysaccharide (LPS) control and positive control with dexamethasone. Results: The infusion, 20% and 50% methanolic fractions and their subfractions, as well as their dominating compounds, e.g., ligstroside, formoside and oleoacteoside isolated from the leaves, show the ability to increase the IL-10 receptor expression on the surface of monocyte/macrophage cells, stimulated by LPS, and to decrease the secretion of pro-inflammatory cytokines, e.g., TNF-α, IL-6.

Chemical Profile, Cytotoxic Activity and Oxidative Stress Reduction of Different Syringa vulgaris L. Extracts

Syringa vulgaris L. (common lilac) is one of the most popular ornamental species, but also a promising not comprehensively studied source of bioactive compounds with important therapeutic potential. Our study was designed to characterize the chemical composition and to assess the antioxidant and cytotoxic properties of ethanolic extracts obtained from S. vulgaris L. flowers, leaves, bark, and fruit. The chemical profile of the ethanolic extracts was investigated using chromatographic (HPLC-DAD-ESI⁺, GC-MS) and spectral (UV-Vis, FT-IR) methods, while the protective effect against free radicals was evaluated in vitro by different chemical assays (DPPH, FRAP, CUPRAC). The cytotoxic activity was tested on two tumoral cell lines, HeLa, B16F10, using the MTT assay. Significant amounts of free or glycosylated chemical components belonging to various therapeutically important structural classes, such as phenyl-propanoids (syringin, acteoside, echinacoside), flavonoids (quercetin, kaempferol derivatives) and secoiridoids (secologanoside, oleuropein, 10-hydroxy oleuropein, demethyloleuropein, syringalactone A, nuzhenide, lingstroside) were obtained for the flowers, leaves and bark extracts, respectively. Furthermore, MTT tests pointed out a significant cytotoxic potential expressed in a non-dose-dependent manner toward the tumoral lines. The performed methods underlined that S. vulgaris extracts, in particular belonging to flowers and leaves, represent valuable sources of compounds with antioxidant and antitumoral potential.

Traditional uses, phytochemistry and pharmacology of genus Syringa: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Genus Syringa, which belongs to Oleaceae family, contains 21 accepted species mainly distributed in Southeast Europe, Japan, China, Himalayas, etc. The various parts of Syringa species have been used as traditional Chinese herbal medicines for treatment of cough, myocardial ischemia, acute icteric hepatitis, diarrhea, conjunctivitis, bronchitis and other ailments.

AIM OF THE STUDY

A more comprehensive and in-depth review about the phytochemistry, pharmacology, traditional medicinal uses and clinical applications as well as toxicology of Syringa have summarized and hope to provide a relatively novel angle for further clinical applicantion on genus.

MATERIALS AND METHODS

The literatures about Syringa were collected via a series of scientific search engines including Web of Science, PubMed, Elsevier, Google Scholar, SciFinder and CNKI.

RESULTS

The phytochemical studies revealed that about 302 compounds include phenylpropanoids, iridoids, phenylethanols, flavonoids, triterpenes and other minor compounds have been isolated and identified from Syringa species. Phenylpropanoids and iridoids are the main constituents among these compounds and may be responsible for the activities directly or indirectly. As traditional medicine, Syringa applied to treat cough, diarrhea, acute icteric hepatitis, vomit, abdominal pain, bronchitis and other ailments. Most of traditional uses are related the biological activities and confirmed by modern studies. Pharmacological researches in vitro and in vivo revealed that the extracts and pure compounds possessed significantly hepatoprotective, anti-inflammatory, antimicrobial, antioxidant, antitumor, antiviral, cardioprotective, immunomodulatory and other activities.

CONCLUSIONS

The phytochemistry, pharmacology, traditional uses and clinical applications described in this article demonstrated that Syringa species possessed a huge number of activities and these findings will promote the further action mechanisms studies. However, fewer preclinical and clinical studies are focued on the pharmacokinetics of crudes extracts and conpounds from Syringa. The explored of new agents with Syringa species as ingredients may be limited. It points to the further in-depth investigations on pharmacokinetics as well as toxicological are essential in future for assessment the effectiveness and safety of drug.

Grindelia squarrosa Extract and Grindelic Acid Modulate Pro-inflammatory Functions of Respiratory Epithelium and Human Macrophages

Aim of the study: Both nasal and bronchial epithelial cells have evolved sophisticated mechanisms involved in cellular response to bacterial infection. Recognition of pathogens by TLR receptors activate the NF-κB transcription factor, and lead to production of wide spectrum of cytokines (TNF-α, IL-1β, IL-6 and IL-8). Released by epithelium proinflammatory cytokines intensify migration of macrophages to damaged tissues and modulate their pro-inflammatory functions. Based on traditional use of G. squarrosa aerial parts we hypothesized that successful treatment of cold-related diseases may arise from modulation of the pro-inflammatory functions of respiratory epithelium and human monocytes/macrophages. The biological activity of G. squarrosa extract and grindelic acid were compared with clarithromycin and budesonide used as positive controls.

Methods: The expression of surface receptors (TLR-4, IL-10) and expression of adhesive molecules (ICAM-1, VCAM-1, E-selectin) was analyzed with flow cytometry. The macrophage attachment to the epithelial cells was assessed fluorimetrically. The p65 NF-κB concentration and cytokine production was measured spectrophotometrically using enzyme-linked immunosorbent assay. Antibacterial activity was examined by the standard disc-diffusion method and serial dilution method according to CLSI guidelines.

Results:G. squarrosa extract and grindelic acid had no antimicrobial effect. However, we noticed significant modulation of pro-inflammatory functions of LPS-stimulated nasal and bronchial epithelium. G. squarrosa extract treatment resulted in decrease of TLR-4 expression and p65 NF-κB concentration and inhibition of cytokines synthesis (IL-8, TNF-α, IL-1β and IL-6) in both cellular models. Additionally, G. squarrosa extract slightly modulated ICAM-1 expression affecting on attachment of macrophages to epithelium. Only G. squarrosa extract was able to stimulate the anti-inflammatory functions of macrophages by inducing TGF-β release and IL-10 receptor surface expression. Grindelic acid, identified as a dominant compound in the plant extract, modulated pro-inflammatory functions of epithelium and macrophages slightly.

Conclusion: The obtained results support traditional use of Grindelia squarrosa preparations for a treatment cold-associated diseases symptoms. In our opinion, the observed biological effect of extract may be a consequence of synergistic effect of all compounds present in the extract.

Syringa vulgaris leaves powder a novel low-cost adsorbent for methylene blue removal: isotherms, kinetics, thermodynamic and optimization by Taguchi method

In this study, the potential of a new low-cost adsorbent, Syringa vulgaris leaves powder, for methylene blue adsorption from aqueous solution was investigated. The adsorbent surface was examined using SEM and FTIR techniques. The experiments were conducted, in batch system, to find out the effect of pH, contact time, adsorbent dose, initial dye concentration, temperature and ionic strength on dye adsorption. The process is best described by Langmuir isotherm and the pseudo second order kinetic model. Maximum adsorption capacity, 188.2 (mg g⁻¹), is better than other similar adsorbent materials. Thermodynamic parameters revealed a spontaneous and endothermic process, suggesting a physisorption mechanism. A Taguchi orthogonal array (L₂₇) experimental design was used to determine the optimum conditions for the removal of dye. Various desorbing agents were used to investigate the regeneration possibility of used adsorbent. Results suggest that the adsorbent material is very effective for removal of methylene blue from aqueous solutions.

Effect of polyphenols from Syringa vulgaris on blood stasis syndrome

In this study, we employed a previously developed in vivo assay system to determine whether the flowers and leaves of Syringa vulgaris (S. vulgaris; commonly known as "lilac") can prevent blood stasis syndrome, known as oketsu in Japanese. This syndrome is considered an important pathology in traditional Chinese and Japanese medicine, and is related to diseases such as peripheral vascular disorders, blood vessel inflammation, and platelet aggregation, whose severities are augmented owing to lipid peroxidation, free radicals, and oxidative stress. The assay system employed in this study monitored the blood flow decrease in the tail vein of mice subjected to sensitization with hen egg white lysozyme. Through bioassay-guided fractionation of different S. vulgaris extracts, five polyphenols were isolated and identified. Among them, quercetine 3-glucoside, quercetin 3-rutinoside, and acteoside were identified as active compounds, as they significantly mitigated blood flow reduction. These findings indicate that the polyphenols obtained from S. vulgaris could be useful for preventing oketsu and improve the quality of life of individuals with disorders and diseases such as gynecopathy, cold sensitivity, poor circulation, allergy, and lifestyle-related diseases.

Effect of polyphenols from Syringa vulgaris on blood stasis syndrome

In this study, we employed a previously developed in vivo assay system to determine whether the flowers and leaves of Syringa vulgaris (S. vulgaris; commonly known as "lilac") can prevent blood stasis syndrome, known as oketsu in Japanese. This syndrome is considered an important pathology in traditional Chinese and Japanese medicine, and is related to diseases such as peripheral vascular disorders, blood vessel inflammation, and platelet aggregation, whose severities are augmented owing to lipid peroxidation, free radicals, and oxidative stress. The assay system employed in this study monitored the blood flow decrease in the tail vein of mice subjected to sensitization with hen egg white lysozyme. Through bioassay-guided fractionation of different S. vulgaris extracts, five polyphenols were isolated and identified. Among them, quercetine 3-glucoside, quercetin 3-rutinoside, and acteoside were identified as active compounds, as they significantly mitigated blood flow reduction. These findings indicate that the polyphenols obtained from S. vulgaris could be useful for preventing oketsu and improve the quality of life of individuals with disorders and diseases such as gynecopathy, cold sensitivity, poor circulation, allergy, and lifestyle-related diseases.

UHPLC-DAD-ESI-MS/MS and HPTLC profiling of ash leaf samples from different commercial and natural sources and their in vitro effects on mediators of inflammation

INTRODUCTION

In European traditional medicine, common ash leaf infusion is recommended by European Medicines Agency to treat minor articular pain and to increase the amount of urine for flushing minor urinary complaints. However, a comprehensive ultra-high-performance liquid chromatography diode array detector electrospray ionisation tandem mass spectrometry (UHPLC-DAD-ESI-MS/MS) analysis of this pharmacopeial plant material has never been performed. Moreover, the number of biological and pharmacological investigations proving the usefulness of this plant material in recommended traditional uses is surprisingly small.

OBJECTIVE

Phytochemical profiling of ash leaf samples from different commercial and natural sources and the determination of the in vitro effects on inflammatory mediators in a model of human neutrophils.

METHODS

Ash leaf samples were characterised by total hydroxycinnamic acid content and by high-performance thin layer chromatography (HPTLC), UHPLC-DAD-ESI-MS/MS methods. The effects of leaf infusions on reactive oxygen species (ROS), tumor necrosis factor (TNF-α), interleukin 8 (IL-8), interleukin 1β (IL-1β), and monocyte chemoattractant protein 1 (MCP-1) production by neutrophils were measured using luminol-dependent chemiluminescence and enzyme-linked immunosorbent assay (ELISA).

RESULTS

In ash leaf samples 64 compounds were identified or partly identified together with four unknown compounds. The major compounds detected belong to different structural groups, including phenolic acid derivatives, phenylethanoids, flavonoids, iridoids, secoiridoids and lignans. The major compounds detected in ash samples were chlorogenic acid, quercetin-3-O-rutinoside, verbascoside, oleuropein and ligstroside. However, one sample contained coumarin derivatives. This finding suggested adulteration with other Fraxinus species and/or plant parts. All infusions were able to inhibit ROS, cytokine and chemokine production.

CONCLUSIONS

The performed phytochemical and biological analyses contribute to the knowledge about this pharmacopeial plant material and supports its traditional use to treat minor inflammatory complaints.

The Oleaceae family: A source of secoiridoids with multiple biological activities

In the quest to search and discover bioactive compounds from nature, terpenoids have emerged as one of the most interesting and researched classes of compounds. Secoiridoid, a type of the terpenoid, has also been extensively studied, especially their chemical structures and pharmacological effects. Oleaceae is a family of woody dicotyledonous plants with broad economic and medicinal values. This family contains a large number of flavonoids, monoterpenoids, iridoids, secoiridoids and phenylethyl alcohols, of which the secoiridoids have various biological activities. The purpose of this review is to summarize the phytochemical and pharmacological of the secoiridoids (glycosides, aglycones, derivatives and dimers) in the Oleaceae family from 1987 to 2018. This review will also serve as a reference for further studies.

Effects of Phytochemically Characterized Extracts From Syringa vulgaris and Isolated Secoiridoids on Mediators of Inflammation in a Human Neutrophil Model

Aim of the study: The aim of the present study was to investigate the effects of phytochemically characterized extracts connected with the traditional use (infusions and ethanolic extracts) of different parts of Syringa vulgaris (common lilac) on the pro-inflammatory functions of neutrophils. Active compounds were isolated from the most promising extract(s) using bioassay-guided fractionation, and their activity and molecular mechanisms of action were determined.

Methods: The extracts were characterized using a HPLC-DAD- MSⁿ method. The effects on ROS, MMP-9, TNF-α, IL-8, and MCP-1 production by neutrophils were measured using luminol-dependent chemiluminescence and enzyme-linked immunosorbent assay (ELISA) methods. The effects on p38MAPK, ERK1/2, JNK phosphorylation, and NF-kB p65 translocation were determined using western blots.

Results: The major compounds detected in the extracts and infusions belong to structural groups, including caffeic acid derivatives, flavonoids, and iridoids. All extracts and infusions were able to significantly reduce ROS and IL-8 production. Bioassay-guided fractionation led to the isolation of the following secoiridoids: 2″-epiframeroside, oleonuezhenide, oleuropein, ligstroside, neooleuropein, hydroxyframoside, and framoside. Neooleuropein appeared to be the most active compound in the inhibition of cytokine production by attenuating the MAP kinase pathways.

Conclusion: The present study demonstrated that common lilac, which is a traditionally used medicinal plant in Europe, is a valuable source of active compounds, especially neooleuropein.