Pinosylvin Induces Cell Survival, Migration and Anti-Adhesiveness of Endothelial Cells via Nitric Oxide Production

Engineered biosynthesis of plant polyketides by type III polyketide synthases in microorganisms

Plant specialized metabolites occupy unique therapeutic niches in human medicine. A large family of plant specialized metabolites, namely plant polyketides, exhibit diverse and remarkable pharmaceutical properties and thereby great biomanufacturing potential. A growing body of studies has focused on plant polyketide synthesis using plant type III polyketide synthases (PKSs), such as flavonoids, stilbenes, benzalacetones, curcuminoids, chromones, acridones, xanthones, and pyrones. Microbial expression of plant type III PKSs and related biosynthetic pathways in workhorse microorganisms, such as Saccharomyces cerevisiae, Escherichia coli, and Yarrowia lipolytica, have led to the complete biosynthesis of multiple plant polyketides, such as flavonoids and stilbenes, from simple carbohydrates using different metabolic engineering approaches. Additionally, advanced biosynthesis techniques led to the biosynthesis of novel and complex plant polyketides synthesized by diversified type III PKSs. This review will summarize efforts in the past 10 years in type III PKS-catalyzed natural product biosynthesis in microorganisms, especially the complete biosynthesis strategies and achievements.

Polyphenols–Gut–Heart: An Impactful Relationship to Improve Cardiovascular Diseases

A healthy gut provides the perfect habitat for trillions of bacteria, called the intestinal microbiota, which is greatly responsive to the long-term diet; it exists in a symbiotic relationship with the host and provides circulating metabolites, hormones, and cytokines necessary for human metabolism. The gut–heart axis is a novel emerging concept based on the accumulating evidence that a perturbed gut microbiota, called dysbiosis, plays a role as a risk factor in the pathogenesis of cardiovascular disease. Consequently, recovery of the gut microbiota composition and function could represent a potential new avenue for improving patient outcomes. Despite their low absorption, preclinical evidence indicates that polyphenols and their metabolites are transformed by intestinal bacteria and halt detrimental microbes’ colonization in the host. Moreover, their metabolites are potentially effective in human health due to antioxidant, anti-inflammatory, and anti-cancer effects. The aim of this review is to provide an overview of the causal role of gut dysbiosis in the pathogenesis of atherosclerosis, hypertension, and heart failure; to discuss the beneficial effects of polyphenols on the intestinal microbiota, and to hypothesize polyphenols or their derivatives as an opportunity to prevent and treat cardiovascular diseases by shaping gut eubiosis.

Neurotoxicity and Structure-Activity Relationships of Resveratrol and its two Natural Analogs, 4,4′-Dihydroxystilbene and Pinosylvin

Resveratrol (RES) and its two natural analogues, 4,4′-dihydroxystilbene (DHS) and pinosylvin (PIN), are very important polyphenols and have attracted considerable pharmaceutical interest because of their diverse biological activities. However, their adverse effects on motor nerves and glioma cells have not been properly assessed. Herein, we surveyed the toxicity and analyzed the structure-activity relationship of these three polyphenols using transgenic zebrafish ( Danio rerio) and U87. Results indicated that, in zebrafish embryos, both DHS (1 and 10 μg/mL) with hydroxyl groups at the 4 and 4′ positions, and PIN (1 and 10 μg/mL) with hydroxyl groups at the 3 and 5 positions inhibited motor neuron growth more effectively than RES (1 and 10 μg/mL) with hydroxyl groups at the 3, 4′, and 5 positions, although their appearance is normal. Both the DHS- (10 μg/mL) and PIN (10 μg/mL) -treated groups significantly reduced the swimming distance of zebrafish compared with the RES (10 μg/mL) -treated group. In addition, DHS with the hydroxyl groups at the 4 and 4′ positions (0.002, 0.02, 0.2, 2, and 20 μM) inhibited U87 cell aggregation in a concentration-dependent manner; PIN with the hydroxyl groups at the 3 and 5 positions (0.002, 0.02, 0.2, 2, and 20 μM) promoted U87 cell aggregation in a concentration-dependent manner, while RES with three hydroxyl groups promoted U87 cell aggregation at concentrations from 0.2 to 2 μM. Taken together, DHS and PIN are more neurotoxic than RES. The position and number of hydroxyl groups significantly affected the ability of the polyphenols to aggregate into tumors in the U87 cell.

Natural Sources and Pharmacological Properties of Pinosylvin

Pinosylvin (3,5-dihydroxy-trans-stilbene), a natural pre-infectious stilbenoid toxin, is a terpenoid polyphenol compound principally found in the Vitaceae family in the heartwood of Pinus spp. (e.g., Pinus sylvestris) and in pine leaf (Pinus densiflora). It provides defense mechanisms against pathogens and insects for many plants. Stilbenoids are mostly found in berries and fruits but can also be found in other types of plants, such as mosses and ferns. This review outlined prior research on pinosylvin, including its sources, the technologies used for its extraction, purification, identification, and characterization, its biological and pharmacological properties, and its toxicity. The collected data on pinosylvin was managed using different scientific research databases such as PubMed, SciFinder, SpringerLink, ScienceDirect, Wiley Online, Google Scholar, Web of Science, and Scopus. In this study, the findings focused on pinosylvin to understand its pharmacological and biological activities as well as its chemical characterization to explore its potential therapeutic approaches for the development of novel drugs. This analysis demonstrated that pinosylvin has beneficial effects for various therapeutic purposes such as antifungal, antibacterial, anticancer, anti-inflammatory, antioxidant, neuroprotective, anti-allergic, and other biological functions. It has shown numerous and diverse actions through its ability to block, interfere, and/or stimulate the major cellular targets responsible for several disorders.

Identifying insomnia-related chemicals through integrative analysis of genome-wide association studies and chemical-genes interaction information

STUDY OBJECTIVES

Insomnia is a common sleep disorder and constitutes a major issue in modern society. We provide new clues for revealing the association between environmental chemicals and insomnia.

METHODS

Three genome-wide association studies (GWAS) summary datasets of insomnia (n = 113,006, n = 1,331,010, and n = 453,379, respectively) were driven from the UK Biobank, 23andMe, and deCODE. The chemical-gene interaction dataset was downloaded from the Comparative Toxicogenomics Database. First, we conducted a meta-analysis of the three datasets of insomnia using the METAL software. Using the result of meta-analysis, transcriptome-wide association studies were performed to calculate the expression association testing statistics of insomnia. Then chemical-related gene set enrichment analysis (GSEA) was used to explore the association between chemicals and insomnia.

RESULTS

For GWAS meta-analysis dataset of insomnia, we identified 42 chemicals associated with insomnia in brain tissue (p < 0.05) by GSEA. We detected five important chemicals such as pinosylvin (p = 0.0128), bromobenzene (p = 0.0134), clonidine (p = 0.0372), gabapentin (p = 0.0372), and melatonin (p = 0.0404) which are directly associated with insomnia.

CONCLUSION

Our study results provide new clues for revealing the roles of environmental chemicals in the development of insomnia.

A mechanistic insight of phytoestrogens used for Rheumatoid arthritis: An evidence-based review

Assessment of the potential therapeutic benefits offered by naturally occurring phytoestrogens necessitate inspection of their potency and sites of action in impeding the chronic, systemic, autoimmune, joint destructing disorder Rheumatoid arthritis (RA). Possessing structural and functional similarity with human estrogen, phytoestrogen promisingly replaces the use of hormone therapy in eradicating RA symptoms with their anti-inflammatory, anti-oxidative, anti-proliferative, anti-angiogenesis, immunomodulatory, joint protection properties abolishing the harmful side effects of synthetic drugs. Scientific evidences revealed that use of phytoestrogens from different chemical categories including flavonoids, alkaloids, stilbenoids derived from different plant species manifest beneficial effects on RA through various cellular mechanisms including suppression of pro-inflammatory cytokines in particular tumor necrosis factor (TNF-α), interleukin(IL-6) and nuclear factor kappa B (NF-κB) and destructive metalloproteinases, inhibition of oxidative stress, suppressing inflammatory signalling pathways, attenuating osteoclastogenesis ameliorating cartilage degradation and bone erosion. This review summarizes the evidences of different phytoestrogen treatment and their pharmacological mechanisms in both in vitro and in vivo studies along with discussing clinical evaluations in RA patients showing phytoestrogen as a promising agent for RA therapy. Further investigations and more clinical trials are mandatory to clarify the utility of these plant derived compounds in RA prevention and in managing oestrogen deficient diseases in patients.

Chemical constituents of the antiulcer purified fractions of Lindera reflexa Hemsl. and its quantitative analysis

The root of Lindera reflexa Hemsl. (LR) is a folk Chinses herbal medicine that has been used to treat gastritis and peptic ulcers. In this study, three new stilbenes (1-3) and two known flavonoids (4 and 5) were isolated from the antiulcer purified fractions of LR. The chemical structures of the isolated compounds were characterized comprehensively based on the basis of extensive spectroscopic data. Absolute configurations of compounds 1, 2, and 3 were determined by ECD calculations. The cytotoxic activities of compounds 1-5 were evaluated by MTT assay. Compound 4 showed the strongest inhibitory effect on the proliferation of tumor cells lines MGC803 and SMMC-7721, with IC₅₀ values of 2.65 and 4.13 μM, respectively. The quantitative analysis of 12 compounds of the antiulcer purified fractions of LR were carried out by using the reversed-phase high-performance liquid chromatography (HPLC) method. Within the test range, all calibration curves showed good linearity (R² > 0.9993). The LOD, LOQ, specificity, precision, and accuracy of the method were verified. Therefore, the present study may provide a valuable method for quality control the antiulcer purified fractions of LR.

Molecular basis for drug repurposing to study the interface of the S protein in SARS-CoV-2 and human ACE2 through docking, characterization, and molecular dynamics for natural drug candidates

A novel coronavirus (SARS-CoV-2) identified in Wuhan state of China in 2019 is the causative agent of deadly disease COVID-19. It has spread across the globe (more than 210 countries) within a short period. Coronaviruses pose serious health threats to both humans and animals. A recent publication reported an experimental 3D complex structure of the S protein of SARS-CoV-2 showed that the ectodomain of the SARS-CoV-2 S protein binds to the peptidase domain (PD) of human ACE2 with a dissociation constant (Kd) of ~ 15 nM. In this study, we focused on inhibitors for ACE2: S protein complex using virtual screening and inhibition studies through molecular docking for over 200,000 natural compounds. Toxicity analysis was also performed for the best hits, and the final complex structures for four complexes were subjected to 400 ns molecular dynamics simulations for stability testing. We found two natural origin inhibitors for the S protein: human ACE2 complex (Andrographolide and Pterostilbene) which displayed better inhibition potential for ACE2 receptor and its binding with the S protein of SARS-CoV-2. Comparative studies were also performed to test and verify that these two drug candidates are also better than hydroxychloroquine which is known to inhibit this complex. However, we needed better potential drug candidates to overcome the side effects of hydroxychloroquine. Supplementary experimental studies need to be carried forward to corroborate the viability of these two new inhibitors for ACE2: S protein complex so as to curb down COVID-19.

Stilbene-based natural compounds as promising drug candidates against COVID-19

The pandemic coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents a great threat to public health. Currently, no potent medicine is available to treat COVID-19. Quest for new drugs especially from natural plant sources is an area of immense potential. The current study aimed to repurpose stilbenoid analogs, reported for some other biological activities, against SARS-CoV-2 spike protein and human ACE2 receptor complex for their affinity and stability using molecular dynamics simulation and binding free energy analysis based on molecular docking. Four compounds in total were probed for their binding affinity using molecular docking. All of the compounds showed good affinity (> -7 kcal/mol). However, fifty nanoseconds molecular dynamic simulation in aqueous solution revealed highly stable bound conformation of resveratrol to the viral protein: ACE2 receptor complex. Net free energy of binding using MM-PBSA also affirmed the stability of the resveratrol-protein complex. Based on the results, we report that stilbene based compounds in general and resveratrol, in particular, can be promising anti-COVID-19 drug candidates acting through disruption of the spike protein. Our findings in this study are promising and call for further in vitro and in vivo testing of stiblenoids, especially resveratrol against the COVID-19. [Formula: see text] Communicated by Ramaswamy H. SarmaHighlightsStilbenoid analogs could be potential disruptors of SARS-CoV-2 spike protein and human ACE2 receptor complex.In particular, resveratrol revealed highly stable conformation to the viral protein: ACE2 receptor complex.The strong interaction of resveratrol is affirmed by molecular dynamic simulation studies and better net free energies.

Novel Carbazole-Based N-Heterocyclic Carbene Ligands to Access Synthetically Relevant Stilbenes in Pd-Catalyzed Coupling Processes

A series of new carbazole-based N-heterocyclic carbene (NHC) ligands have been synthesized in a simple and facile synthetic route and subsequently used in a Pd/carbazole-based NHC catalytic system, which was found to be effective in catalyzing Heck reactions to provide substituted stilbene derivatives in good yields. Several bioactive stilbenes, including pterostilbene, pinosylvin, trimethoxy resveratrol, and resveratrol, were synthesized in good yields, and a 10 mmol scale-up was also performed for trimethoxy resveratrol. The synthetic application was also extended by performing a double-tandem chemoselective Heck reaction followed by Miyaura borylation in a one-pot procedure to give single-step access to synthetically useful stilbenyl boronate esters. Similarly, a unique triple-tandem protocol of a chemoselective Heck reaction/Miyaura borylation/Suzuki-Miyaura coupling reaction sequence was performed for the one-pot modification of biologically relevant molecules.

Pharmacokinetics and Tissue Distribution Study of Pinosylvin in Rats by Ultra-High-Performance Liquid Chromatography Coupled with Linear Trap Quadrupole Orbitrap Mass Spectrometry

Pinosylvin is a potential anti-inflammatory and antioxidant compound and the major effective medicinal ingredient in the root of Lindera reflexa Hemsl. However, few investigations have been conducted regarding the pharmacokinetics, excretion, characteristics of tissue distribution, and major metabolites of pinosylvin in rats after oral administration. To better understand the behavior and mechanisms of action underlying the activity of pinosylvin in vivo, we established a simple, sensitive, and reliable ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for quantifying pinosylvin in rat plasma, urine, feces, and various tissues (including heart, liver, spleen, lung, kidneys, large intestine, small intestine, and stomach). Noncompartmental pharmacokinetic parameters indicated that pinosylvin is rapidly distributed and taken up by tissues. The time to peak (maximum) concentration (T_max) was 0.137 h, and the apparent elimination half-life (t_1/2) was 1.347±0.01 h. The results of the tissue distribution study suggest that pinosylvin is widely distributed to various tissues; the highest concentration was observed after 10 min in the stomach, followed by the heart, lung, spleen, and kidneys. Results of the excretion study suggest that a small amount of pinosylvin is excreted from the urine and feces in the parent form; the 73 h accumulative excretion ratios of urine and feces were 0.82% and 0.11%, respectively. It is likely that pinosylvin is mostly metabolized in vivo. Nine metabolites were found, and the main metabolic pathways of pinosylvin in rats included glucuronidation, hydroxylation, and methylation. Four metabolites had higher concentrations in the stomach, suggesting that the stomach is a potential target organ of pinosylvin. In conclusion, the present study may provide a material basis for studying the pharmacological action of pinosylvin and provides meaningful information for the clinical treatment of chronic gastritis and gastric ulcers using Radix Linderae Reflexae.

Engineering stilbene metabolic pathways in microbial cells

Numerous in vitro and in vivo studies on biological activities of phytostilbenes have brought to the fore the remarkable properties of these compounds and their derivatives, making them a top storyline in natural product research fields. However, getting stilbenes in sufficient amounts for routine biological activity studies and make them available for pharmaceutical and/or nutraceutical industry applications, is hampered by the difficulty to source them through synthetic chemistry-based pathways or extraction from the native plants. Hence, microbial cell cultures have rapidly became potent workhorse factories for stilbene production. In this review, we present the combined efforts made during the past 15 years to engineer stilbene metabolic pathways in microbial cells, mainly the Saccharomyces cerevisiae baker yeast, the Escherichia coli and the Corynebacterium glutamicum bacteria. Rationalized approaches to the heterologous expression of the partial or the entire stilbene biosynthetic routes are presented to allow the identification and/or bypassing of the major bottlenecks in the endogenous microbial cell metabolism as well as potential regulations of the genes involved in these metabolic pathways. The contributions of bioinformatics to synthetic biology are developed to highlight their tremendous help in predicting which target genes are likely to be up-regulated or deleted for controlling the dynamics of precursor flows in the tailored microbial cells. Further insight is given to the metabolic engineering of microbial cells with "decorating" enzymes, such as methyl and glycosyltransferases or hydroxylases, which can act sequentially on the stilbene core structure. Altogether, the cellular optimization of stilbene biosynthetic pathways integrating more and more complex constructs up to twelve genetic modifications has led to stilbene titers ranging from hundreds of milligrams to the gram-scale yields from various carbon sources. Through this review, the microbial production of stilbenes is analyzed, stressing both the engineering dynamic regulation of biosynthetic pathways and the endogenous control of stilbene precursors.

Pinosylvin exacerbates LPS-induced apoptosis via ALOX 15 upregulation in leukocytes

Pinosylvin is known to have anti-inflammatory activity in endothelial cells. In this study, we found that pinosylvin had a pro-apoptotic activity in lipopolysaccharide (LPS)-preconditioned leukocytes. This finding suggests that pinosylvin has an effect on the resolution of inflammation. To understand the detailed mechanism, we examined if pinosylvin enhances cyclooxygenase (COX) or lipoxygenase (LOX) activity in THP-1 and U937 cells. LOX activity was found to be markedly increased by pinosylvin, whereas COX activity was not altered. Furthermore, we found that pinosylvin enhanced both levels of ALOX 15 mRNA and protein, implying that LOX activity, elevated by pinosylvin, is attributed to upregulation of ALOX 15 expression. From this cell signaling study, pinosylvin appeared to promote phosphorylations of ERK and JNK. ERK or JNK inhibitors were found to attenuate ALOX 15 expression and LPS-induced apoptosis promoted by pinosylvin. In conclusion, pinosylvin enhances the apoptosis of LPS-preconditioned leukocytes by up-regulating ALOX 15 expression through ERK and JNK. These findings suggest that pinosylvin may induce the resolution of inflammation.

Pinosylvin enhances leukemia cell death via down-regulation of AMPKα expression

Resveratrol at high concentrations (50-100 μmol/L) is known to induce cell death in leukemia cells. Here, we investigated whether pinosylvin, a resveratrol analogue, induced cell death in leukemia cells. Cell death was found to be markedly elevated by 50- to 100-μmol/L pinosylvin in THP-1 and U937 cells. It was also shown that pinosylvin induced caspase-3 activation, flip-flop of phosphatidylserine, LC3-II accumulation, LC3 puncta, and p62 degradation in both THP-1 and U937 cells. These data indicate that pinosylvin-induced cell death may occur through apoptosis and autophagy. In addition, we showed that pinosylvin down-regulates AMP-activated protein kinase α1 (AMPKα1) in leukemia cells. Therefore, we correlated AMPKα1 down-regulation and leukemia cell death. AMPKα1 inhibition appeared to decrease pinosylvin-induced apoptosis and autophagy in leukemia cells, implying that AMPK is a key regulator of leukemia cell death. Moreover, we found that both pinosylvin-induced autophagy and apoptotic progress were reduced in AMPKα1-overexpressed leukemia cells, when compared with vector-transfected cells. Cell death was elevated by AMPKα1 overexpression, whereas pinosylvin-induced cell death was markedly decreased by caspase-3 inhibitors or autophagy inhibitors. These results suggest that pinosylvin-induced depletion of AMPKα1 enhances cell death via apoptosis and autophagy in leukemia cells.

Nitric oxide promotes epidermal stem cell proliferation via FOXG1-c-Myc signalling

OBJECTIVE

Epidermal stem cells (ESCs) play a critical role in wound repair, but the mechanism underlying ESC proliferation is unclear. Here, we explored the effects of nitric oxide (NO) on ESC proliferation and the possible underlying mechanism.

METHODS

The effect of NO (two NO donors, SNAP and spermine NONOate, were used) on cell proliferation was detected using cell proliferation and DNA synthesis assays. Thereafter, expression of FOXG1 and c-Myc induced by NO was determined by immunoblot analysis. pAdEasy-FOXG1 adenovirus and c-Myc siRNA plasmids were infected or transfected, respectively, into human ESCs to detect the effect of FOXG1 and c-Myc on NO-induced cell proliferation. Additionally, NO-induced ESC proliferation in vivo was detected by BrdU incorporation and a superficial second-degree mouse burn model. Moreover, the relationships among NO, FOXG1 and c-Myc were detected by western blotting, real-time PCR and dual luciferase assay.

RESULTS

NO exerted a biphasic effect on ESC proliferation, and 100 μM SNAP and 10 μM spermine NONOate were the optimal concentrations to promote cell proliferation. Additionally, NO-promoted human ESC proliferation was mediated by FOXG1 and c-Myc in vitro and vivo. Furthermore, NO regulated FOXG1 expression through cGMP signalling, and NO-induced transcription of c-Myc was regulated by FOXG1-mediated c-Myc promoter activity.

CONCLUSION

This study showed that the biphasic effect of NO on ESC proliferation as well as NO induced ESC proliferation were regulated by the cGMP/FOXG1/c-Myc signalling pathway, suggesting that NO may serve as a new disparate target for wound healing.

The O-methyltransferase PMT2 mediates methylation of pinosylvin in Scots pine

Heartwood extractives are important determinants of the natural durability of pine heartwood. The most important phenolic compounds affecting durability are the stilbenes pinosylvin and its monomethylether, which in addition have important functions as phytoalexins in active defense. A substantial portion of the synthesized pinosylvin is 3-methoxylated but the O-methyltransferase responsible for this modification has not been correctly identified. We studied the expression of the stilbene pathway during heartwood development as well as in response to wounding of xylem and UV-C treatment of needles. We isolated and enzymatically characterized a novel O-methyltransferase, PMT2. The methylated product was verified as pinosylvin monomethylether using ultra performance liquid chromatography-tandem mass spectrometry and high performance liquid chromatography analyses. The PMT2 enzyme was highly specific for stilbenes as substrate, in contrast to caffeoyl-CoA O-methyltransferase (CCoAOMT) and PMT1 that were multifunctional. Expression profile and multifunctional activity of CCoAOMT suggest that it might have additional roles outside lignin biosynthesis. PMT1 is not involved in the stilbene pathway and its biological function remains an open question. We isolated a new specific O-methyltransferase responsible for 3-methoxylation of pinosylvin. Expression of PMT2 closely follows stilbene biosynthesis during developmental and stress induction. We propose that PMT2 is responsible for pinosylvin methylation in Scots pine (Pinus sylvestris), instead of the previously characterized methyltransferase, PMT1.

Nitric oxide promotes epidermal stem cell migration via cGMP-Rho GTPase signalling

The migration and reepithelization of epidermal stem cells (ESCs) are the most critical processes in wound healing. The gaseous messenger nitric oxide (NO) has multiple biological effects, but its actions on ESCs are poorly understood. In this study, an NO donor, S-nitroso-N-acetylpenicillamine (SNAP), was found to facilitate the in vitro migration of human ESCs (huESCs) in both live-imaging and scratch models. In addition, pull-down assays demonstrated that SNAP could activate the small GTPases RhoA and Rac1 of the Rho family, but not Cdc42. Moreover, the effects of SNAP on the migration and F-actin polymerization of ESCs could be blocked by inhibitors of cGMP, PKG, RhoA or Rac1, and by a specific siRNA of RhoA or Rac1, but not by a Cdc42 inhibitor or siRNA. Furthermore, the roles of NO in ESC migration via cGMP-Rho GTPase signalling in vivo were confirmed by tracing 5-bromo-2-deoxyuridine (BrdU)-labelled cells in a superficial, partial-thickness scald mouse model. Thus, the present study demonstrated that the NO donor SNAP could promote huESC migration in vitro. Furthermore, NO was found to induce ESC migration via cGMP-Rho GTPase RhoA and Rac1 signalling, but not Cdc42 signalling, both in vivo and in vitro.

Inhibitory effect of the branches of Hovenia dulcis Thunb. and its constituent pinosylvin on the activities of IgE-mediated mast cells and passive cutaneous anaphylaxis in mice

Hovenia dulcis Thunb. (Rhamnaceae) is a hardy tree native to Europe, the Middle East, and North Africa, and it is also grown in parts of Asia and has been used in traditional medicine to treat liver toxicity, stomach disorders, and inflammation. This study investigated the anti-allergy potential of an extract of the branches of H. dulcis (HDB) using the antigen-stimulated mast cell-like cell line rat basophilic leukemia (RBL)-2H3 and a passive cutaneous anaphylaxis (PCA) mouse model. Degranulation assay, reverse transcription PCR, enzyme-lined immunosorbent assays, western blot analyses, and PCA were performed to measure allergic responses and proinflammatory mediators in antigen-stimulated rat basophilic leukemia (RBL)-2H3 mast cells and the PCA mouse model. In antigen-stimulated RBL-2H3 cells, HDB inhibited the secretion of β-hexosaminidase (indicating the inhibition of degranulation) and histamine release; decreased expression and production of the inflammatory mediators, cyclooxygenase-2 and prostaglandin E2, and cytokines interleukin-4 and tumor necrosis factor-α; and suppressed activation of nuclear factor κB, a transcription factor involved in the response to cytokines. HDB attenuated phosphorylation of the mast cell downstream effectors Lyn, Syk, phospholipase Cγ, protein kinase Cμ, extracellular signal-regulated kinase and p38. In IgE-sensitized mice, HDB inhibited mast cell-dependent PCA. Furthermore, HDB contained pinosylvin and possessed significant anti-allergic activities. These results suggest that HDB would be of value in the prevention and treatment of allergic diseases.

Polyphenol Stilbenes: Molecular Mechanisms of Defence against Oxidative Stress and Aging-Related Diseases

Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD), and Alzheimer's disease (AD). In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2) mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed.

Pinosylvin at a high concentration induces AMPK-mediated autophagy for preventing necrosis in bovine aortic endothelial cells

Pinosylvin is a known functional compound of the Pinus species. Pinosylvin at low concentrations (∼pmol/L) was reported to promote cell proliferation in endothelial cells. However, this study found that pinosylvin at a high concentration (100 μmol/L) induces cell death in bovine aortic endothelial cells. Therefore, we examined how pinosylvin was associated with apoptosis, autophagy, and necrosis. Pinosylvin at a high concentration appeared to promote caspase-3 activation, nuclear condensation, and the “flip-flop” of phosphatidylserine, indicating that pinosylvin induces apoptosis. However, based on flow cytometry data obtained from double-staining with annexin V and propidium iodide, pinosylvin was shown to inhibit necrosis, a postapoptotic process. Pinosylvin induced LC3 conversion from LC3-I to LC3-II and p62 degradation, which are important indicators of autophagy. In addition, AMP-activated protein kinase (AMPK) appeared to be activated by pinosylvin, and an AMPK inhibitor was markedly shown to reduce the LC3 conversion. The inhibitory effect of an AMPK inhibitor was reversed by pinosylvin. These results suggest that pinosylvin induces autophagy via AMPK activation. Further, necrosis was found to be promoted by an autophagy inhibitor and then restored by pinosylvin, while the caspase-3 inhibitor had no effect on necrosis. These findings indicate that pinosylvin-induced autophagy blocks necrotic progress in endothelial cells.

Metabolic engineering of Escherichia coli for the synthesis of the plant polyphenol pinosylvin

Plant polyphenols are of great interest for drug discovery and drug development since many of these compounds have health-promoting activities as treatments against various diseases, such as diabetes, cancer, or heart diseases. However, the limited availability of polyphenols represents a major obstacle to clinical applications that must be overcome. In comparison to the quantities of these compounds obtained by isolation from natural sources or costly chemical synthesis, the microbial production of these compounds could provide sufficient quantities from inexpensive substrates. In this work, we describe the development of an Escherichia coli platform strain for the production of pinosylvin, a stilbene found in the heartwood of pine trees which could aid in the treatment of various cancers and cardiovascular diseases. Initially, several configurations of the three-step biosynthetic pathway to pinosylvin were constructed from a set of two different enzymes for each enzymatic step. After optimization of gene expression and evaluation of different construct environments, low pinosylvin concentrations up to 3 mg/liter could be detected. Analysis of the precursor supply and a comparative analysis of the intracellular pools of pathway intermediates and product identified the limited malonyl coenzyme A (malonyl-CoA) availability and low stilbene synthase activity in the heterologous host to be the main bottlenecks during pinosylvin production. Addition of cerulenin for increasing intracellular malonyl-CoA pools and the in vivo evolution of the stilbene synthase from Pinus strobus for improved activity in E. coli proved to be the keys to elevated product titers. These measures allowed product titers of 70 mg/liter pinosylvin from glucose, which could be further increased to 91 mg/liter by the addition of l-phenylalanine.

Notoginsenoside Ft1 activates both glucocorticoid and estrogen receptors to induce endothelium-dependent, nitric oxide-mediated relaxations in rat mesenteric arteries

Panax notoginseng (Burk.) F.H. Chen has been used traditionally for the treatment of cardiovascular diseases. Notoginsenoside Ft1 (Ft1) is a bioactive saponin from the leaves of P. notoginseng. Experiments were designed to determine whether or not Ft1 is an endothelium-dependent vasodilator. Rat mesenteric arteries were suspended in organ chambers for the measurement of isometric tension during phenylephrine-induced contractions. The cyclic guanosine monophosphate (cGMP) level was assessed using enzyme immunoassay. The phosphorylation and protein expressions of endothelial nitric oxide synthase (eNOS), glucocorticoid receptors (GR), estrogen receptors beta (ERß), protein kinase B (Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) were determined by Western blotting. The localization of GR and ERß were determined by immunofluorescence staining. Ft1 caused endothelium-dependent relaxations, which were abolished by l-NAME (inhibitor of nitric oxide synthases) and ODQ (inhibitor of soluble guanylyl cyclase). Ft1 increased the cGMP level in rat mesenteric arteries. GR and ERß were present in the endothelial layer and their antagonism by RU486 and PHTPP, respectively, inhibited Ft1-induced endothelium-dependent relaxations and phosphorylations of eNOS, Akt and ERK1/2. Inhibition of phosphoinositide-3-kinase (PI3K) by wortmannin and ERK1/2 by U0126 reduced Ft1-evoked relaxations and eNOS phosphorylation. Taken in conjunction, the present findings suggest that Ft1 stimulates endothelial GRs and ERßs with subsequent activation of the PI3K/Akt and ERK1/2 pathways in rat mesenteric arteries. This results in phosphorylation of eNOS and the release of NO, which activates soluble guanylyl cyclase in the vascular smooth muscle cells leading to relaxations.