Identification and characterization of [6]-shogaol from ginger as inhibitor of vascular smooth muscle cell proliferation

Investigating the anti-atherosclerotic effects and potential mechanism of Dalbergia odorifera in ApoE-deficient mice using network pharmacology combined with metabolomics

Dalbergia odorifera (DO) is a precious rosewood species in Southern Asia, and its heartwood is used in China as an official plant for invigorating blood circulation and eliminating stasis. This study aims to evaluate the efficacy of DO on atherosclerosis (AS), and further explore its active components and potential mechanisms. The apolipoprotein-E (ApoE)-deficient mice fed a high-fat diet were used as model animals, and the pathological changes in mice with or without DO treatment were compared to evaluate the pharmacodynamics of DO on AS. The mechanisms were preliminarily expounded by combining with metabolomics and network pharmacology. Moreover, the bioactive components and targets were assessed by cell experiments and molecular docking, respectively. Our findings suggested that DO significantly modulated blood lipid levels and alleviated intimal hyperplasia in atherosclerotic-lesioned mice, and the mechanisms may involve the regulation of 18 metabolites that changed during the progression of AS, thus affecting 3 major metabolic pathways and 3 major signaling pathways. Moreover, the interactions between 16 compounds with anti-proliferative effect and hub targets in the 3 signaling pathways were verified using molecular docking. Collectively, our findings preliminarily support the therapeutic effect of DO in atherosclerosis, meanwhile explore the active constituents and potential pharmacological mechanisms, which is conducive to its reasonable exploitation and utilization.

An integrated approach for identifying the efficacy and potential mechanisms of TCM against atherosclerosis-Wu-Zhu-Yu decoction as a case study

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS) is a chronic disease that is associated with high morbidity. However, therapeutic approaches are limited. Wu-Zhu-Yu decoction (WZYD) is a well-known traditional Chinese medicine prescription that is traditionally used to treat headaches and vomiting. Modern studies have demonstrated the cardiotonic effects of WZYD. However, whether WZYD can alleviate AS and its underlying mechanisms remain unclear.

AIM OF THE STUDY

This study aims to investigate the antiatherosclerotic efficacy of WZYD and illustrate its potential mechanisms using an integrated approach combining in vivo and in vitro assessments, including metabolomics, network pharmacology, cell experiments, and molecular docking analyses.

MATERIALS AND METHODS

In this work, an atherosclerotic mouse model was established by administering a high-fat diet to apolipoprotein-E deficient (ApoE^-/-) mice for twelve weeks. Meanwhile, the mice were intragastrically administered WZYD at different dosages. Efficacy evaluation was performed through biochemical and histopathological assessments. The potential active constituents, metabolites, and targets of WZYD in atherosclerosis were predicted by metabolomics combined with network pharmacology analysis, the constituents and targets were further assessed through cell experiments and molecular docking analysis.

RESULTS

WZYD decreased the lipid levels in serum, reduced the areas of aortic lesions, and attenuated intimal thickening, which had antiatherosclerotic effects in ApoE^-/- mice. Metabolomics and network pharmacology approach revealed that the ten constituents (6-shogaol, evodiamine, isorhamnetin, quercetin, beta-carotene, 8-gingerol, kaempferol, 6-paradol, 10-gingerol, and 6-gingerol) of WZYD affected 24 metabolites by acting on the candidate targets, thus resulting in changes in five metabolic pathways (sphingolipid metabolism; glycine, serine and threonine metabolism; arachidonic acid metabolism; tryptophan metabolism; and fatty acid biosynthesis pathway). Cell experiments indicated that the ten key compounds showed antiproliferative effects on the vascular smooth muscle cell. Moreover, the key compounds exhibited direct interactions with the key targets, as assessed by molecular docking analysis.

CONCLUSION

This study revealed that WZYD exerted therapeutic effects on atherosclerosis, and the potential mechanisms were elucidated. Furthermore, it offered a powerful integrated strategy for studying the efficacy of traditional Chinese medicine and exploring its active components and possible mechanisms.

Nutritional benefits of ginger for patients with non-communicable diseases

Ginger (Zingiber officinale) is a famous dietary spice rich in bioactive components like gingerols, and it has been used for a long time as food and medicine. Indeed, clinical studies have confirmed the anti-inflammatory and antioxidant properties of ginger. Thus, ginger seems to be an excellent complementary nutritional strategy for non-communicable diseases (NCD) such as obesity, diabetes, cardiovascular disease and chronic kidney disease. This narrative review aims to discuss the possible effects of ginger on the mitigation of common complications such as inflammation, oxidative stress, and gut dysbiosis in NCD.

Ginger Constituent 6-Shogaol Inhibits Inflammation- and Angiogenesis-Related Cell Functions in Primary Human Endothelial Cells

Rhizomes from Zingiber officinale Roscoe are traditionally used for the treatment of a plethora of pathophysiological conditions such as diarrhea, nausea, or rheumatoid arthritis. While 6-gingerol is the pungent principle in fresh ginger, in dried rhizomes, 6-gingerol is dehydrated to 6-shogaol. 6-Shogaol has been demonstrated to exhibit anticancer, antioxidative, and anti-inflammatory actions more effectively than 6-gingerol due to the presence of an electrophilic Michael acceptor moiety. In vitro, 6-shogaol exhibits anti-inflammatory actions in a variety of cell types, including leukocytes. Our study focused on the effects of 6-shogaol on activated endothelial cells. We found that 6-shogaol significantly reduced the adhesion of leukocytes onto lipopolysaccharide (LPS)-activated human umbilical vein endothelial cells (HUVECs), resulting in a significantly reduced transmigration of THP-1 cells through an endothelial cell monolayer. Analyzing the mediators of endothelial cell–leukocyte interactions, we found that 30 µM of 6-shogaol blocked the LPS-triggered mRNA and protein expression of cell adhesion molecules. In concert with this, our study demonstrates that the LPS-induced nuclear factor κB (NFκB) promoter activity was significantly reduced upon treatment with 6-shogaol. Interestingly, the nuclear translocation of p65 was slightly decreased, and protein levels of the LPS receptor Toll-like receptor 4 remained unimpaired. Analyzing the impact of 6-shogaol on angiogenesis-related cell functions in vitro, we found that 6-shogaol attenuated the proliferation as well as the directed and undirected migration of HUVECs. Of note, 6-shogaol also strongly reduced the chemotactic migration of endothelial cells in the direction of a serum gradient. Moreover, 30 µM of 6-shogaol blocked the formation of vascular endothelial growth factor (VEGF)-induced endothelial sprouts from HUVEC spheroids and from murine aortic rings. Importantly, this study shows for the first time that 6-shogaol exhibits a vascular-disruptive impact on angiogenic sprouts from murine aortae. Our study demonstrates that the main bioactive ingredient in dried ginger, 6-shogaol, exhibits beneficial characteristics as an inhibitor of inflammation- and angiogenesis-related processes in vascular endothelial cells.

Vasculoprotective effects of ginger (Zingiber officinale Roscoe) and underlying molecular mechanisms

Ginger (Zingiber officinale Roscoe) is a common and widely used spice. It is rich in various chemical constituents, including phenolic compounds, terpenes, polysaccharides, lipids, organic acids, and raw fibers. Herein, we reviewed its effects on the vascular system. Studies utilizing cell cultures or animal models showed that ginger constituents alleviate oxidative stress and inflammation, increase nitric oxide synthesis, suppress vascular smooth muscle cell proliferation, promote cholesterol efflux from macrophages, inhibit angiogenesis, block voltage-dependent Ca2+ channels, and induce autophagy. In clinical trials, ginger was shown to have a favorable effect on serum lipids, inflammatory cytokines, blood pressure, and platelet aggregation. Taken together, these studies point to the potential benefits of ginger and its constituents in the treatment of hypertension, coronary artery disease, peripheral arterial diseases, and other vascular diseases.

Phytotherapy for Cardiovascular Disease: A Bench-to-Bedside Approach

At present, cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, and global trends suggest that this panorama will persist or worsen in the near future. Thus, optimization of treatment strategies and the introduction of novel therapeutic alternatives for CVD represent key objectives in contemporary biomedical research. In recent years, phytotherapy-defined as the therapeutic use of whole or minimally modified plant components-has ignited large scientific interest, with a resurgence of abundant investigation on a wide array of medicinal herbs (MH) for CVD and other conditions. Numerous MH have been observed to intervene in the pathophysiology of CVD via a myriad of molecular mechanisms, including antiinflammatory, anti-oxidant, and other beneficial properties, which translate into the amelioration of three essential aspects of the pathogenesis of CVD: Dyslipidemia, atherosclerosis, and hypertension. Although the preclinical data in this scenario is very rich, the true clinical impact of MH and their purported mechanisms of action is less clear, as large-scale robust research in this regard is in relatively early stages and faces important methodological challenges. This review offers a comprehensive look at the most prominent preclinical and clinical evidence currently available concerning the use of MH in the treatment of CVD from a bench-to-bedside approach.

The Effect of Natural Antioxidants on Quality and Shelf Life of Beef and Beef Products

Oxidation processes are the major cause of deterioration of meat quality and shelf life of meat products, leading to negative changes in nutritive value and in sensory and physicochemical properties of meat. Until now, the synthetic antioxidants like butylated hydroxyl anisole have been commonly used to prevent oxidation, which however may cause potential human health risks and increase toxicity of the product. However, natural antioxidants can be the alternative solution for this problem since plants and plant materials are rich in bioactive compounds (as natural antioxidants) with potential health beneficial effects. Moreover, the interest of consumers in using natural products is still increasing. There is an expectation of replacing synthetic antioxidants and preservatives by natural ones. Therefore, the aim of the present review is to provide information on the effect of natural antioxidants from vegetables and fruits like olives, pomegranate or grapes, and herbs and spices like rosemary, oregano, sage, black cumin or turmeric, rich in bioactive compounds on quality and shelf life of beef and beef products.

Leoligin-inspired synthetic lignans with selectivity for cell-type and bioactivity relevant for cardiovascular disease

Recently, a natural compound leoligin, a furan-type lignan, was discovered as an interesting hit compound with an anti-inflammatory pharmacological activity profile. We developed a modular and stereoselective approach for the synthesis of the edelweiss-derived lignan leoligin and used the synthetic route to rapidly prepare leoligin analogs even on the gram scale. Proof of concept of this approach together with cell-based bio-assays gained structural analogs with increased selectivity towards vascular smooth muscle versus endothelial cell proliferation inhibition, a major benefit in fighting vascular neointima formation. In addition, we identified the structural features of leoligin analogs that define their ability to inhibit the pro-inflammatory NF-κB pathway. Results are discussed in the context of structural modification of these novel synthetic lignans.

Bioactive Compounds and Bioactivities of Ginger (Zingiber officinale Roscoe)

Ginger (Zingiber officinale Roscoe) is a common and widely used spice. It is rich in various chemical constituents, including phenolic compounds, terpenes, polysaccharides, lipids, organic acids, and raw fibers. The health benefits of ginger are mainly attributed to its phenolic compounds, such as gingerols and shogaols. Accumulated investigations have demonstrated that ginger possesses multiple biological activities, including antioxidant, anti-inflammatory, antimicrobial, anticancer, neuroprotective, cardiovascular protective, respiratory protective, antiobesity, antidiabetic, antinausea, and antiemetic activities. In this review, we summarize current knowledge about the bioactive compounds and bioactivities of ginger, and the mechanisms of action are also discussed. We hope that this updated review paper will attract more attention to ginger and its further applications, including its potential to be developed into functional foods or nutraceuticals for the prevention and management of chronic diseases.

Identification and Quantification of Bioactive Compounds in Diaphragma juglandis Fructus by UHPLC-Q-Orbitrap HRMS and UHPLC-MS/MS

Diaphragma juglandis fructus is the dry wooden diaphragm inside walnuts and a byproduct in food processing of walnut kernels. The purpose of our research is to enrich the information on compounds in Diaphragma juglandis fructus to further discover and exploit its potential nutritional value. In this study, new quali-quantitative analytical approaches were developed to identify and determine bioactive compounds in Diaphragma juglandis fructus. Two-hundred compounds, including hydrolyzable tannins, flavonoids, phenolic acids, and quinones, were identified by UHPLC-Q-Orbitrap HRMS, more than 150 of which were first discovered in Diaphragma juglandis fructus. Among them, 21 major dietary polyphenols with health-promoting effects were successfully quantified using UHPLC-MS/MS, with total contents of 2.88-6.18 mg/g. This successful characterization and quantification of bioactive compounds in Diaphragma juglandis fructus gives a better understanding of its potential nutritional value and supports efficiently developing and reusing it instead of discarding it as agrofood waste.

Up-regulation of heme oxygenase-1 expression and inhibition of disease-associated features by cannabidiol in vascular smooth muscle cells

Aberrant proliferation and migration of vascular smooth muscle cells (VSMC) have been closely linked to the development and progression of cardiovascular and cancer diseases. The cytoprotective enzyme heme oxygenase-1 (HO-1) has been shown to mediate anti-proliferative and anti-migratory effects in VSMC. This study investigates the effect of cannabidiol (CBD), a non-psychoactive cannabinoid, on HO-1 expression and disease-associated functions of human umbilical artery smooth muscle cells (HUASMC). HO-1 protein and mRNA were significantly increased by CBD in a time- and concentration-dependent manner. Although the expression of several cannabinoid-activated receptors (CB₁, CB₂, G protein-coupled receptor 55, transient receptor potential vanilloid 1) was verified in HUASMC, CBD was shown to induce HO-1 via none of these targets. Instead, the CBD-mediated increase in HO-1 protein was reversed by the glutathione precursor N-acetylcysteine, indicating the participation of reactive oxygen species (ROS) signaling; this was confirmed by flow cytometry-based ROS detection. CBD-induced HO-1 expression was accompanied by inhibition of growth factor-mediated proliferation and migration of HUASMC. However, neither inhibition of HO-1 activity nor knockdown of HO-1 protein attenuated CBD-mediated anti-proliferative and anti-migratory effects. Indeed, inhibition or depletion of HO-1 resulted in induction of apoptosis and intensified CBD-mediated effects on proliferation and migration. Collectively, this work provides the first indication of CBD-mediated enhancement of HO-1 in VSMC and potential protective effects against aberrant VSMC proliferation and migration. On the other hand, our data argue against a role of HO-1 in CBD-mediated inhibition of proliferation and migration while substantiating its anti-apoptotic role in oxidative stress-mediated cell fate.

Vascular smooth muscle cell proliferation as a therapeutic target. Part 1: molecular targets and pathways

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules and signaling pathways. Herein, we recapitulated the importance of signaling cascades relevant for the regulation of vascular cell proliferation. Detailed understanding of the mechanism underlying this process is essential for the identification of new lead compounds (e.g., natural products) for vascular therapies.

Constituents of Mediterranean Spices Counteracting Vascular Smooth Muscle Cell Proliferation: Identification and Characterization of Rosmarinic Acid Methyl Ester as a Novel Inhibitor

SCOPE

Aberrant vascular smooth muscle cell (VSMC) proliferation is involved in atherosclerotic plaque formation and restenosis. Mediterranean spices have been reported to confer cardioprotection, but their direct influence on VSMCs has largely not been investigated. This study aims at examining rosmarinic acid (RA) and 11 related constituents for inhibition of VSMC proliferation in vitro, and at characterizing the most promising compound for their mode of action and influence on neointima formation in vivo.

METHODS AND RESULTS

RA, rosmarinic acid methyl ester (RAME), and caffeic acid methyl ester inhibit VSMC proliferation in a resazurin conversion assay with IC50 s of 5.79, 3.12, and 6.78 µm, respectively. RAME significantly reduced neointima formation in vivo in a mouse femoral artery cuff model. Accordingly, RAME leads to an accumulation of VSMCs in the G0 /G1 cell-cycle phase, as indicated by blunted retinoblastoma protein phosphorylation upon mitogen stimulation and inhibition of cyclin-dependent kinase 2 in vitro.

CONCLUSION

RAME represses PDGF-induced VSMC proliferation in vitro and reduces neointima formation in vivo. These results recommend RAME as an interesting compound with VSMC-inhibiting potential. Future metabolism and pharmacokinetics studies might help to further evaluate the potential relevance of RAME and other spice-derived polyphenolics for vasoprotection.

Occurrence, biological activity and metabolism of 6-shogaol

As one of the main bioactive compounds of dried ginger, 6-shogaol has been widely used to alleviate many ailments. It is also a major pungent flavor component, and its precursor prior to dehydration is 6-gingerol, which is reported to be responsible for the pungent flavor and biological activity of fresh ginger. Structurally, gingerols including 6-gingerol have a β-hydroxyl ketone moiety and is liable to dehydrate to generate an α,β-unsaturated ketone under heat and/or acidic conditions. The conjugation of the α,β-unsaturated ketone skeleton in the chemical structure of 6-shogaol explicates its higher potency and efficacy than 6-gingerol in terms of antioxidant, anti-inflammatory, anticancer, antiemetic and other bioactivities. Research on the health benefits of 6-shogaol has been conducted and results have been reported recently; however, scientific data are scattered due to a lack of systematic collection. In addition, action mechanisms of the preventive and/or therapeutic actions of 6-shogaol remain obscurely non-collective. Herein, we review the preparations, biological activity and mechanisms, and metabolism of 6-shogaol as well as the properties of 6-shogaol metabolites.

Xanthohumol Blocks Proliferation and Migration of Vascular Smooth Muscle Cells in Vitro and Reduces Neointima Formation in Vivo

Xanthohumol (1) is a principal prenylated chalcone found in hops. The aim of this study was to examine its influence on platelet-derived growth factor (PDGF)-BB-triggered vascular smooth muscle cell (VSMC) proliferation and migration in vitro and on experimentally induced neointima formation in vivo. Quantification of resazurin conversion indicated that 1 can inhibit PDGF-BB-induced VSMC proliferation concentration-dependently (IC₅₀ = 3.49 μM). Furthermore, in a wound-healing assay 1 potently suppresses PDGF-BB-induced VSMC migration at 15 μM. Tested in a mouse femoral artery cuff model, 1 significantly reduces neointima formation. Taken together, we show that 1 represses PDGF-BB-induced VSMC proliferation and migration in vitro as well as neointima formation in vivo. This novel activity suggests 1 as an interesting candidate for further studies addressing a possible therapeutic application to counteract vascular proliferative disease.

Anti-atherosclerotic plants which modulate the phenotype of vascular smooth muscle cells

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of global death, with atherosclerosis being a major contributor to this mortality. Several mechanisms are implicated in the pathogenesis of this disease. A key element in the development and progression of atherosclerotic lesions is the phenotype of vascular smooth muscle cells. Under pathophysiologic conditions such as injury, these cells switch from a contractile to a synthetic phenotype that often possesses high proliferative and migratory capacities.

PURPOSE

Despite major advances made in the management and treatment of atherosclerosis, mortality associated with this disease remains high. This mandates that other approaches be sought. Herbal medicine, especially for the treatment of CVD, has been gaining more attention in recent years. This is in no small part due to the evidence-based values associated with the consumption of many plants as well as the relatively cheaper prices, easier access and conventional folk medicine "inherited" over generations. Sections: In this review, we provide a brief introduction about the pathogenesis of atherosclerosis then we highlight the role of vascular smooth muscle cells in this disease, especially when a phenotypic switch of these cells arises. We then thoroughly discuss the various plants that show potentially beneficial effects as anti-atherosclerotic, with prime attention given to herbs and plants that inhibit the phenotypic switch of vascular smooth muscle cells.

CONCLUSION

Accumulating evidence provides the justification for the use of botanicals in the treatment or prevention of atherosclerosis. However, further studies, especially clinical ones, are warranted to better define several pharmacological parameters of these herbs, such as toxicity, tolerability, and efficacy.

Comparison of fresh, dried and stir-frying gingers in decoction with blood stasis syndrome in rats based on a GC-TOF/MS metabolomics approach

In China, ginger (Zingiberofficinale Rosc.) and its processed products, such as dried ginger and stir-frying ginger are commonly applied in traditional Chinese medicine (TCM). The paper presents the research on the effects of fresh ginger, dried ginger and stir-frying ginger extracts in blood stasis syndrome. First, a blood stasis syndrome rats model was established and then the hemorheological and blood coagulation activities were analyzed. Third, a sensitive, simple, and valid gas chromatography combined with time-of-flight mass spectrometry (GC-TOF/MS) method was established to compare the metabolic fingerprint coupled with multivariate analysis. The total 27 metabolites (16 in serum and 11 in urine) were identified and contributed to the blood stasis progress. These metabolites mainly involve six metabolism pathways in different impact-value. The altered efficacy index and metabolites can be regulated to normal levels by fresh ginger (FG), dried ginger (DG) and stir-frying ginger (SG). FG is the most effective as shown by the efficacy index, similarity analysis and peak intensity. The result presented here shows that metabolomics equipped with efficacy index makes it possible to study the blood stasis syndrome and to compare the effect and metabolites in fresh, dried and stir-frying gingers. The metabolomics approach can be recommended to study the pharmacological effect and mechanism of herbal drugs.

Drugs from nature targeting inflammation (DNTI): a successful Austrian interdisciplinary network project

ABSTRACT

Inflammation is part of numerous pathological conditions, which are lacking satisfying treatment and effective concepts of prevention. A national research network project, DNTI, involving scientists from six Austrian universities as well as several external partners aimed to identify and characterize natural products capable of combating inflammatory processes specifically in the cardiovascular system. The combined use of computational techniques with traditional knowledge, high-tech chemical analysis and synthesis, and a broad range of in vitro, cell-based, and in vivo pharmacological models led to the identification of a series of promising anti-inflammatory drug lead candidates. Mechanistic studies contributed to a better understanding of their mechanism of action and delivered new knowledge on the molecular level of inflammatory processes. Herein, the used approaches and selected highlights of the results of this interdisciplinary project are presented.

GRAPHICAL ABSTRACT

Plumericin inhibits proliferation of vascular smooth muscle cells by blocking STAT3 signaling via S-glutathionylation

The etiology of atherosclerosis and restenosis involves aberrant inflammation and proliferation, rendering compounds with both anti-inflammatory and anti-mitogenic properties as promising candidates for combatting vascular diseases. A recent study identified the iridoid plumericin as a new scaffold inhibitor of the pro-inflammatory NF-κB pathway in endothelial cells. We here examined the impact of plumericin on the proliferation of primary vascular smooth muscle cells (VSMC). Plumericin inhibited serum-stimulated proliferation of rat VSMC. It arrested VSMC in the G1/G0-phase of the cell cycle accompanied by abrogated cyclin D1 expression and hindered Ser 807/811-phosphorylation of retinoblastoma protein. Transient depletion of glutathione by the electrophilic plumericin led to S-glutathionylation as well as hampered Tyr705-phosphorylation and activation of the transcription factor signal transducer and activator of transcription 3 (Stat3). Exogenous addition of glutathione markedly prevented this inhibitory effect of plumericin on Stat3. It also overcame downregulation of cyclin D1 expression and the reduction of biomass increase upon serum exposure. This study revealed an anti-proliferative property of plumericin towards VSMC which depends on plumericin's thiol reactivity and S-glutathionylation of Stat3. Hence, plumericin, by targeting at least two culprits of vascular dysfunction -inflammation and smooth muscle cell proliferation -might become a promising electrophilic lead compound for vascular disease therapy.

Chemical characterization and antioxidant activities comparison in fresh, dried, stir-frying and carbonized ginger

Ginger (Zingiber officinale Rosc.) is a common dietary adjunct that contributes to the taste and flavor of foods, and is also an important Traditional Chinese medicine (TCM). Different processing methods can produce different processed gingers with dissimilar chemical constituents and pharmacological activities. In this study, an ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOF-MS) was applied to identify the complicated components from fresh, dried, stir-frying and carbonized ginger extracts. All of the 27 compounds were identified from four kinds of ginger samples (fresh, dried, stir-frying and carbonized ginger). Five main constituents (zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol) in these four kinds of ginger sample extracts were simultaneously determined by UPLC-PDA. Meanwhile, the antioxidant effect of fresh, dried, stir-frying and carbonized gingers were evaluated by three assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP)). The results demonstrated that antioxidant activity of dried ginger was the highest, for its phenolic contents are 5.2-, 1.1- and 2.4-fold higher than that of fresh, stir-frying and carbonized ginger, respectively, the antioxidant activities' results indicated a similar tendency with phenolic contents: dried ginger>stir-frying ginger>fresh ginger>carbonized ginger. The processing contributed to the decreased concentration of gingerols and the increased levels of shogaols, which reducing the antioxidant effects in pace with processing. This study elucidated the relationship of the heating process with the constituents and antioxidant activity, and provided a guide for choosing different kinds of ginger samples on clinical application.

Nonprenylated Xanthones from Gentiana lutea, Frasera caroliniensis, and Centaurium erythraea as Novel Inhibitors of Vascular Smooth Muscle Cell Proliferation

Aberrant proliferation of vascular smooth muscle cells (VSMC) plays a major role in restenosis, the pathological renarrowing of the blood vessel lumen after surgical treatment of stenosis. Since available anti-proliferative pharmaceuticals produce unfavorable side effects, there is high demand for the identification of novel VSMC proliferation inhibitors. A natural product screening approach using a resazurin conversion assay enabled the identification of gentisin (1) from Gentiana lutea as a novel inhibitor of VSMC proliferation with an IC₅₀ value of 7.84 µM. Aiming to identify further anti-proliferative compounds, 13 additional nonprenylated xanthones, isolated from different plant species, were also tested. While some compounds showed no or moderate activity at 30 µM, 1-hydroxy-2,3,4,5-tetramethoxyxanthone (4), swerchirin (6), and methylswertianin (7) showed IC₅₀ values between 10.2 and 12.5 µM. The anti-proliferative effect of 1, 4, 6, and 7 was confirmed by the quantification of DNA synthesis (BrdU incorporation) in VSMC. Cell death quantification (determined by LDH release in the culture medium) revealed that the compounds are not cytotoxic in the investigated concentration range. In conclusion, nonprenylated xanthones are identified as novel, non-toxic VSMC proliferation inhibitors, which might contribute to the development of new therapeutic applications to combat restenosis.