A new benzoquinone and a new stilbenoid from Paphiopedilum exul (Ridl.) Rolfe

One new alkyl benzoquinone, paphionone (1), one new trans-stilbenoid, (E)-6,5'-dihydroxy-2,3'-dimethoxystilbene (2), and eight known stilbenoids and flavonoids (3-10) were isolated from the leaves and roots of Paphiopedilum exul (Orchidaceae). Their chemical structures were determined based on IR, ECD, MS and NMR analyses. Cytotoxicity of all isolated compounds towards human hepatocellular carcinoma (HepG2) cell line was examined in vitro by MTT assay. The para-hydroxybenzyl substituted stilbene 10 was potently cytotoxic to the cancer cells, with an IC50 value of 4.80 ± 1.10 μM (selectivity index = 20.83). All compounds were non-toxic to normal human embryo fibroblast (OUMS-36) cell line.

Therapeutic potential of stilbenes in neuropsychiatric and neurological disorders: A comprehensive review of preclinical and clinical evidence

Neuropsychiatric disorders are anticipated to be a leading health concern in the near future, emphasizing an outstanding need for the development of new effective therapeutics to treat them. Stilbenes, with resveratrol attracting the most attention, are an example of multi-target compounds with promising therapeutic potential for a broad array of neuropsychiatric and neurological conditions. This review is a comprehensive summary of the current state of research on stilbenes in several neuropsychiatric and neurological disorders such as depression, anxiety, schizophrenia, autism spectrum disorders, epilepsy, traumatic brain injury, and neurodegenerative disorders. We describe and discuss the results of both in vitro and in vivo studies. The majority of studies concentrate on resveratrol, with limited findings exploring other stilbenes such as pterostilbene, piceatannol, polydatin, tetrahydroxystilbene glucoside, or synthetic resveratrol derivatives. Overall, although extensive preclinical studies show the potential benefits of stilbenes in various central nervous system disorders, clinical evidence on their therapeutic efficacy is largely missing.

Grapevine Shoot Extract Rich in Trans-Resveratrol and Trans-ε-Viniferin: Evaluation of Their Potential Use for Cardiac Health

A grapevine shoot extract (GSE) was obtained using ultrasound-assisted extraction and characterized. The main phenolic constituents were identified as stilbenoids. Among them, trans-resveratrol and trans-ε-viniferin stood out. The GSE was administered to an isoproterenol-induced myocardial injury animal model. The extract alleviated the associated symptoms of the administration of the drug, i.e., the plasma lipid profile was improved, while the disturbed plasma ion concentration, the cardiac dysfunction markers, the DNA laddering, and the necrosis of myocardial tissue were diminished. This effect could be related to the anti-oxidative potential of GSE associated with its antioxidant properties, the increased levels of endogenous antioxidants (glutathione and enzymatic antioxidants), and the diminished lipid peroxidative markers in the heart. The results also revealed angiotensin-converting enzyme (ACE)-inhibitory activity, which indicated the potential of GSE to deal with cardiovascular disease events. This work suggests that not only trans-resveratrol has a protective role in heart function but also GSE containing this biomolecule and derivatives. Therefore, GSE has the potential to be utilized in the creation of innovative functional ingredients.

In Silico-Assisted Isolation of trans-Resveratrol and trans-ε-Viniferin from Grapevine Canes and Their Sustainable Extraction Using Natural Deep Eutectic Solvents (NADES)

Grapevine canes are an important source of bioactive compounds, such as stilbenoids. This study aimed to evaluate an in silico method, based on the Conductor-like Screening Model for Real Solvents (COSMO-RS) to isolate stilbenoids from a grapevine cane extract by offline heart-cut high-performance countercurrent chromatography (HPCCC). For the following extraction of resveratrol and ε-viniferin from grapevine canes, natural deep eutectic solvents (NADES) were used as an environmentally friendly alternative to the traditionally used organic solvents. In order to evaluate a variety of combinations of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) for the targeted extraction of stilbenoids, COSMO-RS was applied. In particular, ultrasonic-assisted extraction using a solvent mixture of choline chloride/1,2-propanediol leads to higher extraction yields of resveratrol and ε-viniferin. COSMO-RS calculations for NADES extraction combined with HPCCC biphasic solvent system calculations are a powerful combination for the sustainable extraction, recovery, and isolation of natural products. This in silico-supported workflow enables the reduction of preliminary experimental tests required for the extraction and isolation of natural compounds.

Shoot Cultures of Vitis vinifera (Vine Grape) Different Cultivars as a Promising Innovative Cosmetic Raw Material-Phytochemical Profiling, Antioxidant Potential, and Whitening Activity

The primary purpose of this work was the initiation and optimization of shoot cultures of different Vitis vinifera L. cultivars: cv. Chardonnay, cv. Hibernal, cv. Riesling, cv. Johanniter, cv. Solaris, cv. Cabernet Cortis, and cv. Regent. Cultures were maintained on 30-day growth cycles using two media, Murashige and Skoog (MS) and Schenk and Hildebrandt (SH), with various concentrations of plant growth regulators. Tested media ('W1'-'W4') contained varying concentrations of 6-benzylaminopurine (BA) in addition to indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA). High performance liquid chromatography coupled with mass spectrometry (UPLC-MS) was used for metabolomic profiling. In all tested extracts, 45 compounds were identified (6 amino acids, 4 phenolic acids, 13 flavan-3-ols, 3 flavonols, and 19 stilbenoids). Principal component analysis (PCA) was performed to assess the influence of the genotype and medium on metabolic content. PCA showed that metabolic content was mainly influenced by genotype and to a lesser extent by medium composition. MS media variants induced the amino acid, procyanidin, and flavan-3-ol production. In addition, the antioxidant potential and anti-tyrosinase activity was measured spectrophotometrically. The studies on antioxidant activity clearly reveal very high efficiency in reducing free radicals in the tested extracts. The strongest tyrosinase inhibition capacity was proved for shoots cv. Hibernal cultured in SH medium and supplemented with NAA, with an inhibition of 17.50%. These studies show that in vitro cultures of V. vinifera cvs. can be proposed as an alternative source of plant material that can be potentially used in cosmetic industry.

Additive and synergistic antifungal effects of copper and phenolic extracts from grape cane and apples

BACKGROUND

Organic viticulture seeks sustainable alternatives for eco-toxic copper fungicides to control downy mildew caused by Plasmopara viticola. (Poly)phenol-rich extracts of agricultural byproducts are known to possess antifungal activity, but high production costs often limit their actual implementation.

RESULTS

We developed and produced novel ligninsulfonate-based grape cane extract (GCE) formulations and an apple extract on a pilot plant scale, including a detailed (poly)phenol characterization by high-performance liquid chromatography photodiode array mass spectrometry (HPLC-PDA-MS). Our GCE formulations alone reduced downy mildew disease severity in greenhouse trials by 29%-69% in a dose-dependent manner, whereas a standard application of the copper-based agent alone reached ~56%. When applied together, disease severity was diminished by 78%-92%, revealing a synergistic effect that depended on the mixture ratio. Combining GCE formulations with the apple extract, additive effects were found (80% disease severity reduction).

CONCLUSION

The studied plant extracts are proposed to both substitute for and synergistically reinforce copper fungicides in grapevine downy mildew control. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Characterization of Some Stilbenoids Extracted from Two Cultivars of Lambrusco-Vitis vinifera Species: An Opportunity to Valorize Pruning Canes for a More Sustainable Viticulture

Pruning canes from grape vines are valuable byproducts that contain resveratrol and other health-boosting stilbenoids. This study aimed to assess the effect of roasting temperature on the stilbenoid content of vine canes by comparing two Vitis vinifera cultivars, Lambrusco Ancellotta and Salamino. Samples were collected during different phases of the vine plant cycle. One set was collected in September after the grape harvest and was air-dried and analyzed. A second set was obtained during vine pruning in February and evaluated immediately after collection. The main stilbenoid identified in each sample was resveratrol (~100-2500 mg/kg), with significant levels of viniferin (~100-600 mg/kg) and piceatannol (~0-400 mg/kg). Their contents decreased with increasing roasting temperature and residence time on the plant. This study provides valuable insights into the use of vine canes in a novel and efficient manner, which could potentially benefit different industries. One potential use involves the roasted cane chips to accelerate the aging of vinegars and alcoholic beverages. This method is more efficient and cost-effective than traditional aging, which is slow and unfavorable from an industrial perspective. Furthermore, incorporating vine canes into maturation processes reduces viticulture waste and enhances the final products with health-promoting molecules, such as resveratrol.

Hyperspectral mapping of the response of grapevine cultivars to Plasmopara viticola infection at the tissue scale

Resistance of grapevine to Plasmopara viticola is associated with the hypersensitive reaction, accumulation of stilbenoids, and formation of callose depositions. Spectral characterization of infected leaf tissue of cvs 'Regent' and 'Solaris' with resistance genes Rpv 3-1 and Rpv 10 and Rpv 3-3, respectively, suggested that resistance is not dependent on large-scale necrotization of host tissue. Reactions of the resistant cultivars and a reference susceptible to P. viticola were studied using hyperspectral imaging (range 400-1000 nm) at the tissue level and microscopic techniques. Resistance of both cultivars was incomplete and allowed pathogen reproduction. Spectral vegetation indices characterized the host response to pathogen invasion; the vitality of infected and necrotic leaf tissue differed significantly. Resistance depended on local accumulation of polyphenols in response to haustorium formation and was more effective for cv. 'Solaris'. Although hypersensitive reaction of some cells prevented colonization of palisade parenchyma, resistance was not associated with extensive necrotization of tissue, and the biotrophic pathogen survived localized death of penetrated host cells. Hyperspectral imaging was suitable to characterize and differentiate the resistance reactions of grapevine cultivars by mapping of the cellular response to pathogen attack on the tissue level and yields useful information on host-pathogen interactions.

5'AMP-activated protein kinase: an emerging target of phytochemicals to treat chronic inflammatory diseases

Inflammation is a defensive response of the organism to traumatic, infectious, toxic, ischemic, and autoimmune injury. Inflammatory mediators are released to effectively eliminate the inflammatory trigger and restore homeostasis. However, failure of these processes can lead to chronic inflammatory conditions and diseases such as inflammatory bowel diseases, rheumatoid arthritis, inflammatory lung diseases, atherosclerosis, and neurodegenerative diseases. The cure of chronic inflammatory diseases remains challenging as current therapies have various limitations, such as pronounced side effects, progressive loss of efficacy, and high cost especially for biologics. In this context, phytochemicals (such as alkaloids, flavonoids, lignans, phenolic acids, saponins, terpenoids, and other classes) are considered as an interesting alternative approach. Among the numerous targets of phytochemicals, AMP-activated protein kinase (AMPK) can be considered as an interesting target in the context of inflammation. AMPK regulates inflammatory response by inhibiting inflammatory pathways (NF-κB, JAK/STAT, and MAPK) and regulating several other processes of the inflammatory response (oxidative stress, autophagy, and apoptosis). In this review, we summarize and discuss the studies focusing on phytochemicals that showed beneficial effects by blocking different inflammatory pathways implicating AMPK activation in chronic inflammatory disease models. We also highlight elements to consider when investigating AMPK in the context of phytochemicals.

Neuroprotective Effect of Yucca schidigera Roezl ex Ortgies Bark Phenolic Fractions, Yuccaol B and Gloriosaol A on Scopolamine-Induced Memory Deficits in Zebrafish

Y. schidigera contains a number of unusual polyphenols, derivatives of resveratrol and naringenin, called spiro-flavostilbenoids, which have potent in vitro anti-inflammatory, antioxidant, and moderate cholinesterase inhibitory activities. To date, these compounds have not been tested in vivo for the treatment of neurodegenerative diseases. The aim of the present study was to evaluate the effects of both single spiro-flavostilbenoids (yuccaol B and gloriosaol A) and phenolic fractions derived from Y. schidigera bark on scopolamine-induced anxiety and memory process deterioration using a Danio rerio model. Detailed phytochemical analysis of the studied fractions was carried out using different chromatographic techniques and Nuclear Magnetic Resonance (NMR). The novel tank diving test was used as a method to measure zebrafish anxiety, whereas spatial working memory function was assessed in Y-maze. In addition, acetylcholinesterase/butyrylcholinesterase (AChE/BChE) and 15-lipooxygenase (15-LOX) inhibition tests were performed in vitro. All pure compounds and fractions under study exerted anxiolytic and procognitive action. Moreover, strong anti-oxidant capacity was observed, whereas weak inhibition towards cholinesterases was found. Thus, we may conclude that the observed behavioral effects are complex and result rather from inhibition of oxidative stress processes and influence on cholinergic muscarinic receptors (both 15-LOX and scopolamine assays) than effects on cholinesterases. Y. schidigera is a source of substances with desirable properties in the prevention and treatment of neurodegenerative diseases.

Arachidin-1, a Prenylated Stilbenoid from Peanut, Induces Apoptosis in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is unresponsive to typical hormonal treatments, causing it to be one of the deadliest forms of breast cancer. Investigating alternative therapies to increase survival rates for this disease is essential. The goal of this study was to assess cytotoxicity and apoptosis mechanisms of prenylated stilbenoids in TNBC cells. The prenylated stilbenoids arachidin-1 (A-1) and arachidin-3 (A-3) are analogs of resveratrol (RES) produced in peanut upon biotic stress. The anticancer activity of A-1 and A-3 isolated from peanut hairy root cultures was determined in TNBC cell lines MDA-MB-231 and MDA-MB-436. After 24 h of treatment, A-1 exhibited higher cytotoxicity than A-3 and RES with approximately 11-fold and six-fold lower IC₅₀, respectively, in MDA-MB-231 cells, and nine-fold and eight-fold lower IC₅₀, respectively, in MDA-MB-436 cells. A-1 did not show significant cytotoxicity in the non-cancerous cell line MCF-10A. While A-1 blocked cell division in G2-M phases in the TNBC cells, it did not affect cell division in MCF-10A cells. Furthermore, A-1 induced caspase-dependent apoptosis through the intrinsic pathway by activating caspase-9 and PARP cleavage, and inhibiting survivin. In conclusion, A-1 merits further research as a potential lead molecule for the treatment of TNBC.

Synthesis and Antimicrobial Activity of δ-Viniferin Analogues and Isosteres

The natural stilbenoid dehydro-δ-viniferin, containing a benzofuran core, has been recently identified as a promising antimicrobial agent. To define the structural elements relevant to its activity, we modified the styryl moiety, appended at C5 of the benzofuran ring. In this paper, we report the construction of stilbenoid-derived 2,3-diaryl-5-substituted benzofurans, which allowed us to prepare a focused collection of dehydro-δ-viniferin analogues. The antimicrobial activity of the synthesized compounds was evaluated against S. aureus ATCC29213. The simplified analogue 5,5'-(2-(4-hydroxyphenyl)benzofuran-3,5-diyl)bis(benzene-1,3-diol), obtained in three steps from 4-bromo-2-iodophenol (63% overall yield), emerged as a promising candidate for further investigation (MIC = 4 µg/mL).

Vitis OneGenE: A Causality-Based Approach to Generate Gene Networks in Vitis vinifera Sheds Light on the Laccase and Dirigent Gene Families

The abundance of transcriptomic data and the development of causal inference methods have paved the way for gene network analyses in grapevine. Vitis OneGenE is a transcriptomic data mining tool that finds direct correlations between genes, thus producing association networks. As a proof of concept, the stilbene synthase gene regulatory network obtained with OneGenE has been compared with published co-expression analysis and experimental data, including cistrome data for MYB stilbenoid regulators. As a case study, the two secondary metabolism pathways of stilbenoids and lignin synthesis were explored. Several isoforms of laccase, peroxidase, and dirigent protein genes, putatively involved in the final oxidative oligomerization steps, were identified as specifically belonging to either one of these pathways. Manual curation of the predicted sequences exploiting the last available genome assembly, and the integration of phylogenetic and OneGenE analyses, identified a group of laccases exclusively present in grapevine and related to stilbenoids. Here we show how network analysis by OneGenE can accelerate knowledge discovery by suggesting new candidates for functional characterization and application in breeding programs.

The Natural Stilbenoid (-)-Hopeaphenol Inhibits Cellular Entry of SARS-CoV-2 USA-WA1/2020, B.1.1.7, and B.1.351 Variants

Antivirals are urgently needed to combat the global SARS-CoV-2/COVID-19 pandemic, supplement existing vaccine efforts, and target emerging SARS-CoV-2 variants of concern. Small molecules that interfere with binding of the viral spike receptor binding domain (RBD) to the host angiotensin-converting enzyme II (ACE2) receptor may be effective inhibitors of SARS-CoV-2 cell entry. Here, we screened 512 pure compounds derived from natural products using a high-throughput RBD/ACE2 binding assay and identified (-)-hopeaphenol, a resveratrol tetramer, in addition to vatalbinoside A and vaticanol B, as potent and selective inhibitors of RBD/ACE2 binding and viral entry. For example, (-)-hopeaphenol disrupted RBD/ACE2 binding with a 50% inhibitory concentration (IC50) of 0.11 μM, in contrast to an IC50 of 28.3 μM against the unrelated host ligand/receptor binding pair PD-1/PD-L1 (selectivity index, 257.3). When assessed against the USA-WA1/2020 variant, (-)-hopeaphenol also inhibited entry of a VSVΔG-GFP reporter pseudovirus expressing SARS-CoV-2 spike into ACE2-expressing Vero-E6 cells and in vitro replication of infectious virus in cytopathic effect and yield reduction assays (50% effective concentrations [EC50s], 10.2 to 23.4 μM) without cytotoxicity and approaching the activities of the control antiviral remdesivir (EC50s, 1.0 to 7.3 μM). Notably, (-)-hopeaphenol also inhibited two emerging variants of concern, B.1.1.7/Alpha and B.1.351/Beta in both viral and spike-containing pseudovirus assays with similar or improved activities over the USA-WA1/2020 variant. These results identify (-)-hopeaphenol and related stilbenoid analogues as potent and selective inhibitors of viral entry across multiple SARS-CoV-2 variants of concern.

Recent Advances in Health Benefits of Stilbenoids

Biological targeting or molecular targeting is the main strategy in drug development and disease prevention. However, the problem of "off-targets" cannot be neglected. Naturally derived drugs are preferred over synthetic compounds in pharmaceutical markets, and the main goals are high effectiveness, lower cost, and fewer side effects. Single-target drug binding may be the major cause of failure, as the pathogenesis of diseases is predominantly multifactorial. Naturally derived drugs are advantageous because they are expected to have multitarget effects, but not off-targets, in disease prevention or therapeutic actions. The capability of phytochemicals to modulate molecular signals in numerous diseases has been widely discussed. Among them, stilbenoids, especially resveratrol, have been well-studied, along with their potential molecular targets, including AMPK, Sirt1, NF-κB, PKC, Nrf2, and PPARs. The analogues of resveratrol, pterostilbene, and hydroxylated-pterostilbene may have similar, if not more, potential biological targeting effects compared with their original counterpart. Furthermore, new targets that have been discussed in recent studies are reviewed in this paper.

Resveratrol and Prostate Cancer: The Power of Phytochemicals

Prostate cancer is the fifth cause of tumor-related deaths in man worldwide. Due to its long latency period, this pathology represents an ideal type of disease for chemopreventive studies. Among the drugs considered thus far for the treatment of prostate cancer, the natural compound resveratrol emerged as very promising. Resveratrol is widely recognized as a chemopreventive agent and was shown to potentiate the antitumor activity of conventional chemotherapeutics in several tumors, including prostate cancer. Here, we overview the literature of the last five years and summarize the recent achievements of resveratrol and its derivatives as antimetastatic agents in prostate cancer. Moreover, drug combination studies as well as nanomedicine approaches proposed to improve resveratrol activity and to overcome delivery drawbacks are addressed. The last part of the review discusses the clinical trials containing resveratrol ongoing on cancer patients.

Encapsulation of Phenolic Compounds from a Grape Cane Pilot-Plant Extract in Hydroxypropyl Beta-Cyclodextrin and Maltodextrin by Spray Drying

Grape canes, the main byproducts of the viticulture industry, contain high-value bioactive phenolic compounds, whose application is limited by their instability and poorly solubility in water. Encapsulation in cyclodextrins allows these drawbacks to be overcome. In this work, a grape cane pilot-plant extract (GC_PPE) was encapsulated in hydroxypropyl beta-cyclodextrin (HP-β-CD) by a spray-drying technique and the formation of an inclusion complex was confirmed by microscopy and infrared spectroscopy. The phenolic profile of the complex was analyzed by LC-ESI-LTQ-Orbitrap-MS and the encapsulation efficiency of the phenolic compounds was determined. A total of 42 compounds were identified, including stilbenes, flavonoids, and phenolic acids, and a complex of (epi)catechin with β-CD was detected, confirming the interaction between polyphenols and cyclodextrin. The encapsulation efficiency for the total extract was 80.5 ± 1.1%, with restrytisol showing the highest value (97.0 ± 0.6%) and (E)-resveratrol (32.7 ± 2.8%) the lowest value. The antioxidant capacity of the inclusion complex, determined by ORAC-FL, was 5300 ± 472 µmol TE/g DW, which was similar to the value obtained for the unencapsulated extract. This formulation might be used to improve the stability, solubility, and bioavailability of phenolic compounds of the GC_PPE for water-soluble food and pharmaceutical applications.

Recovery of Polyphenols from Vineyard Pruning Wastes-Shoots and Cane of Hybrid Grapevine (Vitis sp.) Cultivars

Grapevine shoots and canes represent a significant amount of biomass, considered as a waste in viticulture. In cooler climates, grapevines are pruned in the autumn (October) and spring (March) due to harsh winter conditions (e.g., snow, low temperatures), and large amounts of biomass are produced at these different pruning times. This work was undertaken in order to investigate the potential of vineyard pruning waste for recovery of polyphenolic compounds for biomass valorization. Qualitative and quantitative analyses of grapevine shoot and cane polyphenols, including flavonoids and stilbenoids were performed using UHPLC MS/MS method. The results revealed the flavonols (quercetin) to be the most abundant compounds in shoots among all the three cultivars screened (Zilga, Hasansky Sladky, Rondo). Stilbenoids (ε-viniferin) dominated in the canes, while increased level of flavonols with lower contents of stilbenoids was detected in the endo-dormant canes, and higher amounts of flavanols and stilbenoids were recorded in eco-dormant canes. In conclusion, the content of polyphenols in grapevine shoots and canes differed among the cultivars and dormancy phases. The results generated from the present study contribute to the sustainable and environmentally friendly viticulture practice via valorization of vineyard pruning wastes.

Plant-Derived Stilbenoids as DNA-Binding Agents: From Monomers to Dimers

Stilbenoids are natural compounds endowed with several biological activities, including cardioprotection and cancer prevention. Among them, (±)-trans-δ-viniferin, deriving from trans-resveratrol dimerization, was investigated in its ability to target DNA duplex and G-quadruplex structures by exploiting NMR spectroscopy, circular dichroism, fluorescence spectroscopy and molecular docking. (±)-trans-δ-Viniferin proved to bind both the minor and major grooves of duplexes, whereas it bound the 3'- and 5'-ends of a G-quadruplex by stacking on the outer quartets, accompanied by rearrangement of flanking residues. Specifically, (±)-trans-δ-viniferin demonstrated higher affinity for the investigated DNA targets than its monomeric counterpart. Additionally, the methoxylated derivatives of (±)-trans-δ-viniferin and trans-resveratrol, i. e. (±)-pterostilbene-trans-dihydrodimer and trans-pterostilbene, respectively, were evaluated, revealing similar binding modes, affinities and stoichiometries with the DNA targets as their parent analogues. All tested compounds were cytotoxic at μM concentration on several cancer cell lines, showing DNA damaging activity consistent with their ability to tightly interact with duplex and G-quadruplex structures.

The Role of Polyphenols in Abiotic Stress Response: The Influence of Molecular Structure

Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans.

Semi-Targeted Metabolomics to Validate Biomarkers of Grape Downy Mildew Infection Under Field Conditions

Grape downy mildew is a devastating disease worldwide and new molecular phenotyping tools are required to detect metabolic changes associated to plant disease symptoms. In this purpose, we used UPLC-DAD-MS-based semi-targeted metabolomics to screen downy mildew symptomatic leaves that expressed oil spots (6 dpi, days post-infection) and necrotic lesions (15 dpi) under natural infections in the field. Leaf extract analyses enabled the identification of 47 metabolites belonging to the primary metabolism including 6 amino acids and 1 organic acid, as well as an important diversity of specialized metabolites including 9 flavonols, 11 flavan-3-ols, 3 phenolic acids, and stilbenoids with various degree of polymerization (DP) including 4 stilbenoids DP1, 8 stilbenoids DP2, and 4 stilbenoids DP3. Principal component analysis (PCA) was applied as unsupervised multivariate statistical analysis method to reveal metabolic variables that were affected by the infection status. Univariate and multivariate statistics revealed 33 and 27 metabolites as relevant infection biomarkers at 6 and 15 dpi, respectively. Correlation-based networks highlighted a general decrease of flavonoid-related metabolites, whereas stilbenoid DP1 and DP2 concentrations increased upon downy mildew infection. Stilbenoids DP3 were identified only in necrotic lesions representing late biomarkers of downy mildew infection.

Stilbenoids from the roots of Stemona tuberosa

Two new stilbenoids, stemobenoids A (1) and B (2), together with three known compounds were obtained from the roots of Stemona tuberosa. The structures of the new compounds were established by extensive spectroscopic analysis, including HRMS, 1D and 2D NMR data. Compounds 1 and 2 displayed potent quinone reductase inducing activity in Hepa 1c1c7 cells.

Stilbenoids: A Natural Arsenal against Bacterial Pathogens

The escalating emergence of resistant bacterial strains is one of the most important threats to human health. With the increasing incidence of multi-drugs infections, there is an urgent need to restock our antibiotic arsenal. Natural products are an invaluable source of inspiration in drug design and development. One of the most widely distributed groups of natural products in the plant kingdom is represented by stilbenoids. Stilbenoids are synthesised by plants as means of protection against pathogens, whereby the potential antimicrobial activity of this class of natural compounds has attracted great interest in the last years. The purpose of this review is to provide an overview of recent achievements in the study of stilbenoids as antimicrobial agents, with particular emphasis on the sources, chemical structures, and the mechanism of action of the most promising natural compounds. Attention has been paid to the main structure modifications on the stilbenoid core that have expanded the antimicrobial activity with respect to the parent natural compounds, opening the possibility of their further development. The collected results highlight the therapeutic versatility of natural and synthetic resveratrol derivatives and provide a prospective insight into their potential development as antimicrobial agents.

Flavonoids and Stilbenoids of the Genera Dracaena and Sansevieria: Structures and Bioactivities

The genera Dracaena and Sansevieria (Asparagaceae, Nolinoideae) are still poorly resolved phylogenetically. Plants of these genera are commonly distributed in Africa, China, Southeast Asia, and America. Most of them are cultivated for ornamental and medicinal purposes and are used in various traditional medicines due to the wide range of ethnopharmacological properties. Extensive in vivo and in vitro tests have been carried out to prove the ethnopharmacological claims and other bioactivities. These investigations have been accompanied by the isolation and identification of hundreds of phytochemical constituents. The most characteristic metabolites are steroids, flavonoids, stilbenes, and saponins; many of them exhibit potent analgesic, anti-inflammatory, antimicrobial, antioxidant, antiproliferative, and cytotoxic activities. This review highlights the structures and bioactivities of flavonoids and stilbenoids isolated from Dracaena and Sansevieria.

Influence of pruning time and viral infection on stilbenoid levels in Pinot noir grape canes

BACKGROUND

Grapevine canes represent a large source of waste derived from grape cultivation. In the present study, the effect of different processes of storage and different pruning times on the stilbene accumulation on Pinot noir canes was analyzed. Whether the alteration of the secondary metabolism accompanying leafroll symptom expressions could affect the stilbenoid accumulation in canes harvested at pruning time was also investigated.

RESULTS

The maximum accumulation of trans-resveratrol and trans-piceatannol was obtained in canes harvested in October and dried at 40 °C. Even in grape canes harvested in October, November, and December and stored for different times at room temperature (20 ± 2 °C) a marked increase in trans-resveratrol and trans-piceatannol was evident, which reached a maximum at around 8 weeks of storage. A significant higher accumulation of trans-resveratrol and trans-piceatannol was also found in canes harvested from symptomatic plants compared to those harvested from asymptomatic plants for all the pruning times.

CONCLUSION

This study confirms that the biosynthetic enzyme activities and, particularly, those involved in the stilbene pathway, persist during Pinot noir cane storage at different harvest times, with different storage times and conditions, and different sanitary status. © 2019 Society of Chemical Industry.

Physical-Chemical Evaluation of Active Food Packaging Material Based on Thermoplastic Starch Loaded with Grape cane Extract

The aim of this paper is to evaluate the physicochemical and microbiological properties of active thermoplastic starch-based materials. The extract obtained from grape cane waste was used as a source of stilbene bioactive components to enhance the functional properties of thermoplastic starch (TPS). The biomaterials were prepared by the compression molding technique and subjected to mechanical, thermal, antioxidant, and microbiological tests. The results showed that the addition of grape cane extract up to 15 wt% (TPS/WE15) did not significantly influence the thermal stability of obtained biomaterials, whereas mechanical resistance decreased. On the other side, among all tested pathogens, thermoplastic starch based materials showed antifungal activity toward Botrytis cinerea and antimicrobial activity toward Staphylococcus aureus, suggesting potential application in food packaging as an active biomaterial layer.

Metabolism of cis- and trans-Resveratrol and Dihydroresveratrol in an Intestinal Epithelial Model

Trans-resveratrol, a well-known plant phenolic compound, has been intensively investigated due to its association with the so-called French paradox. However, despite its high pharmacological potential, trans-resveratrol has shown relatively low bioavailability. Trans-resveratrol is intensively metabolized in the intestine and liver, yielding metabolites that may be responsible for its high bioactivity. The aim of this study was to investigate and compare the metabolism of trans-resveratrol (tRes), cis-resveratrol (cRes) and dihydroresveratrol (dhRes) in an in vitro epithelial model using Caco-2 cell lines. Obtained metabolites of tRes, cRes and dhRes were analyzed by LC/MS Q-TOF, and significant differences in the metabolism of each compound were observed. The majority of tRes was transported unchanged through the Caco-2 cells, while cRes was mostly metabolized. The main metabolite of both cis- and trans-resveratrol observed as a result of colon microbial metabolism, dhRes, was metabolized almost completely, with only traces of the unchanged molecule being found. A sulphate conjugate was identified as the main metabolite of tRes in our model, while a glucuronide conjugate was the major metabolite of cRes and dhRes. Since metabolism of simple phenolics and polyphenols plays a crucial role in their bioavailability, detailed knowledge of their transformation is of high scientific value.

Inhibition of Pancreatic α-amylase by Resveratrol Derivatives: Biological Activity and Molecular Modelling Evidence for Cooperativity between Viniferin Enantiomers

To improve the current understanding of the role of stilbenoids in the management of diabetes, the inhibition of the pancreatic α-amylase by resveratrol derivatives was investigated. To approach in a systematic way, the mechanistic and structural aspects of the interaction, potential bioactive agents were prepared as single molecules, that were used for the biological evaluation of the determinants of inhibitory binding. Some dimeric stilbenoids-in particular, viniferin isomers- were found to be better than the reference drug acarbose in inhibiting the pancreatic α-amylase. Racemic mixtures of viniferins were more effective inhibitors than the respective isolated pure enantiomers at an equivalent total concentration, and displayed cooperative effects not observed with the individual enantiomers. The molecular docking analysis provided a thermodynamics-based rationale for the measured inhibitory ability and for the observed synergistic effects. Indeed, the binding of additional ligands on the surface of the alpha-amylase was found to decrease the dissociation constant of inhibitors bound to the active site of the enzyme, thus providing a mechanistic rationale for the observed inhibitory synergies.

Vineyard evaluation of stilbenoid-rich grape cane extracts against downy mildew: a large-scale study

BACKGROUND

Plasmopara viticola control in organic viticulture requires copper-based fungicides with harmful effects on health and the environment. Plant extracts represent a biorational eco-friendly alternative to copper. The aim of this study was to evaluate the potential of stilbenoid-rich grape cane extract (GCE) against downy mildew on three cultivars over 3 years following natural downy mildew infection.

RESULTS

Over all field trials, GCE treatments showed an average reduction in disease incidence of -35% and -38% on leaves and clusters, respectively. The average reduction in disease severity was -35% and -43% on leaves and clusters, respectively. Under artificial downy mildew infection, GCE efficacy corresponded to 1 g L^-1 of copper. Neither phytotoxicity nor adverse effects on auxiliary fauna were observed after treatment with GCE.

CONCLUSION

Because few or no biocontrol agents are active alone against P. viticola, GCE is a promising alternative to copper-based fungicides. Grape canes, an abundant by-product of viticulture, have great potential for valorization as a biocontrol agent for sustainable viticulture. © 2018 Society of Chemical Industry.

Metabolism of Stilbenoids by Human Faecal Microbiota

Stilbenoids are dietary phenolics with notable biological effects on humans. Epidemiological, clinical, and nutritional studies from recent years have confirmed the significant biological effects of stilbenoids, such as oxidative stress protection and the prevention of degenerative diseases, including cancer, cardiovascular diseases, and neurodegenerative diseases. Stilbenoids are intensively metabolically transformed by colon microbiota, and their corresponding metabolites might show different or stronger biological activity than their parent molecules. The aim of the present study was to determine the metabolism of six stilbenoids (resveratrol, oxyresveratrol, piceatannol, thunalbene, batatasin III, and pinostilbene), mediated by colon microbiota. Stilbenoids were fermented in an in vitro faecal fermentation system using fresh faeces from five different donors as an inoculum. The samples of metabolized stilbenoids were collected at 0, 2, 4, 8, 24, and 48 h. Significant differences in the microbial transformation among stilbene derivatives were observed by liquid chromatography mass spectrometry (LC/MS). Four stilbenoids (resveratrol, oxyresveratrol, piceatannol and thunalbene) were metabolically transformed by double bond reduction, dihydroxylation, and demethylation, while batatasin III and pinostilbene were stable under conditions simulating the colon environment. Strong inter-individual differences in speed, intensity, and pathways of metabolism were observed among the faecal samples obtained from the donors.

Phytochemical Diversity in Rhizomes of Three Reynoutria Species and their Antioxidant Activity Correlations Elucidated by LC-ESI-MS/MS Analysis

The rhizome of Reynoutria japonica is a well-known traditional herb (Hu zhang) used in East Asia to treat various inflammatory diseases, infections, skin diseases, scald, and hyperlipidemia. It is also one of the richest natural sources of resveratrol. Although, it has been recently included in the European Pharmacopoeia, in Europe it is still an untapped resource. Some of the therapeutic effects are likely to be influenced by its antioxidant properties and this in turn is frequently associated with a high stilbene content. However, compounds other than stilbenes may add to the total antioxidant capacity. Hence, the aim of this research was to examine rhizomes of R. japonica and the less studied but morphologically similar species, R. sachalinensis and R. x bohemica for their phytochemical composition and antioxidant activity and to clarify the relationship between the antioxidant activity and the components by statistical methods. HPLC/UV/ESI-MS studies of three Reynoutria species revealed 171 compounds, comprising stilbenes, carbohydrates, procyanidins, flavan-3-ols, anthraquinones, phenylpropanoids, lignin oligomers, hydroxycinnamic acids, naphthalenes and their derivatives. Our studies confirmed the presence of procyanidins with high degree of polymerization, up to decamers, in the rhizomes of R. japonica and provides new data on the presence of these compounds in other Reynoutria species. A procyanidin trimer digallate was described for the first time in, the studied plants. Moreover, we tentatively identified dianthrone glycosides new for these species and previously unrecorded phenylpropanoid disaccharide esters and hydroxycinnamic acid derivatives. Furthermore, compounds tentatively annotated as lignin oligomers were observed for the first time in the studied species. The rhizomes of all Reynoutria species exhibited strong antioxidant activity. Statistical analysis demonstrated that proanthocyanidins should be considered as important contributors to the total antioxidant capacity.

Multi-year Quantitative Evaluation of Stilbenoids Levels Among Selected Muscadine Grape Cultivars

Stilbenoids such as t-piceid, t-resveratrol, ε-viniferins, and t-pterostilbene can differ significantly among grape cultivars and years due to variation in environmental conditions and subsequent stressors encountered during a year. This study evaluated diverse muscadine grape cultivars for their ability to consistently produce four major stilbenoids such as t-piceid, t-resveratrol, ε-viniferins, and t-pterostilbene irrespective of environmental changes that can impact their production. Berries from forty-two muscadine grape cultivars were collected for three years (2013, 2014, and 2015) to measure stilbenoids. Results showed significant differences in the composition of four stilbenoids among the muscadine cultivars. The highest level of stilbenoids was observed in ‘Fry Seedless’ (270.20 µg/g fresh weight) in each of the three consecutive years tested followed by ‘Pride’ (46.18 µg/g fresh weight) while ‘Doreen’ produced the lowest level of stilbenoids (1.73 µg/g fresh weight). Results demonstrated that certain muscadine grape cultivars consistently produced varied levels of the four major stilbenoids year after year. Based on the total content of stilbenoids, the 42 muscadine cultivars studied were grouped into three categories such as High, Medium and Low stilbenoid-containing cultivars. This information will help establish new vineyards with cultivars that are less prone to variations in environmental conditions and can consistently produce stilbenoid-rich muscadine grape berries with enhanced market value to promote consumer health.

Effect of Selected Stilbenoids on Human Fecal Microbiota

Dietary phenolics or polyphenols are mostly metabolized by the human gut microbiota. These metabolites appear to confer the beneficial health effects attributed to phenolics. Microbial composition affects the type of metabolites produced. Reciprocally, phenolics modulate microbial composition. Understanding this relationship could be used to positively impact health by phenolic supplementation and thus create favorable colonic conditions. This study explored the effect of six stilbenoids (batatasin III, oxyresveratrol, piceatannol, pinostilbene, resveratrol, thunalbene) on the gut microbiota composition. Stilbenoids were anaerobically fermented with fecal bacteria from four donors, samples were collected at 0 and 24 h, and effects on the microbiota were assessed by 16S rRNA gene sequencing. Statistical tests identified affected microbes at three taxonomic levels. Observed microbial composition modulation by stilbenoids included a decrease in the Firmicutes to Bacteroidetes ratio, a decrease in the relative abundance of strains from the genus Clostridium, and effects on the family Lachnospiraceae. A frequently observed effect was a further decrease of the relative abundance when compared to the control. An opposite effect to the control was observed for Faecalibacterium prausnitzii, whose relative abundance increased. Observed effects were more frequently attributed to resveratrol and piceatannol, followed by thunalbene and batatasin III.

IL-6 in Osteoarthritis: Effects of Pine Stilbenoids

Interleukin-6 (IL-6) is involved in the pathogenesis of various inflammatory diseases, like rheumatoid arthritis (RA). In the present study, we investigated the role of IL-6 in osteoarthritis (OA) patients and the effects of the stilbenoids monomethyl pinosylvin and pinosylvin on the expression of the cartilage matrix components aggrecan and collagen II and the inflammatory cytokine IL-6 in human OA chondrocytes. Synovial fluid and plasma samples were obtained from 100 patients with severe OA [BMI 29.7 (8.3) kg/m², age 72 (14) years, median (IQR); 62/38 females/males] undergoing total knee replacement surgery. IL-6 and matrix metalloproteinase (MMP) concentrations in synovial fluid and plasma were measured by immunoassay. The effects of pinosylvin on the expression of IL-6, aggrecan, and collagen II were studied in primary cultures of human OA chondrocytes. IL-6 levels in synovial fluid from OA patients [119.8 (193.5) pg/mL, median (IQR)] were significantly increased as compared to the plasma levels [3.1 (2.7) pg/mL, median (IQR)] and IL-6 levels in synovial fluid were associated with MMPs and radiographic disease severity. Natural stilbenoids monomethyl pinosylvin and pinosylvin increased aggrecan expression and suppressed IL-6 production in OA chondrocytes. The results propose that IL-6 is produced within OA joints and has an important role in the pathogenesis of OA. Stilbenoid compounds monomethyl pinosylvin and pinosylvin appeared to have disease-modifying potential in OA chondrocytes.

Antioxidant Activity and Neuroprotective Activity of Stilbenoids in Rat Primary Cortex Neurons via the PI3K/Akt Signalling Pathway

Antioxidant activity and neuroprotective activity of three stilbenoids, namely, trans-4-hydroxystilbene (THS), trans-3,5,4′-trihydroxy-stilbene (resveratrol, RES), and trans-3′,4′,3,5-tetrahydroxy-stilbene (piceatannol, PIC), against β-amyloid (Aβ)-induced neurotoxicity in rat primary cortex neurons were evaluated. THS, RES, and PIC significantly scavenged DPPH• and •OH radicals. All three stilbenoids were able to inhibit Aβ neurotoxicity by decreasing intracellular reactive oxygen species (ROS) via the PI3K/Akt signalling pathway. Specifically, stilbenoids significantly promoted Akt phosphorylation; suppressed Bcl-2/Bax expression; and inhibited caspase-9, caspase-3, and PARP cleavage. Molecular docking between stilbenoids with Akt indicated that stilbenoids could form hydrogen bond interactions with the COOH-terminal region of Akt. Additionally, the neuroprotective activity of stilbenoids correlated with the number and position of hydroxyl groups. The lack of meta-dihydroxyl groups on THS did not affect its neuroprotective activity in comparison with RES, whereas the ortho-dihydroxyl moiety on PIC significantly enhanced neuroprotective activity. These results provide new insights into the correlation between the biological activity and chemical structure of stilbenoids.

The Dietary Antioxidant Piceatannol Inhibits Adipogenesis of Human Adipose Mesenchymal Stem Cells and Limits Glucose Transport and Lipogenic Activities in Adipocytes

Phenolic compounds are among the most investigated herbal remedies, as is especially the case for resveratrol. Many reports have shown its anti-aging properties and the ability to reduce obesity and diabetes induced by high-fat diet in mice. However, such beneficial effects hardly translate from animal models to humans. The scientific community has therefore tested whether other plant phenolic compounds may surpass the effects of resveratrol. In this regard, it has been reported that piceatannol reproduces in rodents the anti-obesity actions of its parent polyphenol. However, the capacity of piceatannol to inhibit adipocyte differentiation in humans has not been characterized so far. Here, we investigated whether piceatannol was antiadipogenic and antilipogenic in human preadipocytes. Human mesenchymal stem cells (hMSC), isolated from adipose tissues of lean and obese individuals, were differentiated into mature adipocytes with or without piceatannol, and their functions were explored. Fifty µM of piceatannol deeply limited synthesis/accumulation of lipids in both murine and hMSC-derived adipocytes. Interestingly, this phenomenon occurred irrespective of being added at the earlier or later stages of adipocyte differentiation. Moreover, piceatannol lowered glucose transport into adipocytes and decreased the expression of key elements of the lipogenic pathway (PPARγ, FAS, and GLUT4). Thus, the confirmation of the antiadipogenic properties of piceatanol in vitro warrants the realization of clinical studies for the application of this compound in the treatment of the metabolic complications associated with obesity.

Subtle Alterations in DNA Methylation Patterns in Normal Cells in Response to Dietary Stilbenoids

SCOPE

Searching for correlations between dietary polyphenols and risk of chronic diseases has been a challenge due to the lack of quantitative evaluation methods of long-term exposure. We previously observed substantial DNA methylation changes in human cancer cells upon treatment with polyphenols of the stilbenoid class. When induced in normal cells, such molecular changes may persist and reflect chronic exposure.

METHODS AND RESULTS

Illumina 450K microarray is used to delineate a genome wide DNA methylation landscape in MCF10A human immortalized mammary epithelial cells exposed to resveratrol (RSV) at noncytotoxic 15 μM dose for 9 days. Subtle alterations are observed suggesting remodeling of DNA methylation patterns rather than switch on/off changes. Using pyrosequencing, DNA methylation is quantitatively measured at eight CpG sites located within KCNJ4, RNF169, BCHE, DAOA, HOXA9, RUNX3, KRTAP2-1, and TAGAP, upon exposure to RSV or pterostilbene and shows similar differences induced by both stilbenoids. Two of the probes, Runx3 and Kcnj4, are successfully verified in whole blood DNA from healthy rats on diets supplemented with stilbenoids.

CONCLUSIONS

The study provides strong support for testing the utility of polyphenol-mediated changes in DNA methylation as quantitative measures of long-term dietary exposures in nutritional epidemiology and clinical trials.

Case-specific potentiation of glioblastoma drugs by pterostilbene

Glioblastoma multiforme (GBM, astrocytoma grade IV) is the most common malignant primary brain tumor in adults. Addressing the shortage of effective treatment options for this cancer, we explored repurposing of existing drugs into combinations with potent activity against GBM cells. We report that the phytoalexin pterostilbene is a potentiator of two drugs with previously reported anti-GBM activity, the EGFR inhibitor gefitinib and the antidepressant sertraline. Combinations of either of these two compounds with pterostilbene suppress cell growth, viability, sphere formation and inhibit migration in tumor GBM cell (GC) cultures. The potentiating effect of pterostilbene was observed to a varying degree across a panel of 41 patient-derived GCs, and correlated in a case specific manner with the presence of missense mutation of EGFR and PIK3CA and a focal deletion of the chromosomal region 1p32. We identify pterostilbene-induced cell cycle arrest, synergistic inhibition of MAPK activity and induction of Thioredoxin interacting protein (TXNIP) as possible mechanisms behind pterostilbene's effect. Our results highlight a nontoxic stilbenoid compound as a modulator of anticancer drug response, and indicate that pterostilbene might be used to modulate two anticancer compounds in well-defined sets of GBM patients.

Discovering Causal Relationships in Grapevine Expression Data to Expand Gene Networks. A Case Study: Four Networks Related to Climate Change

In recent years the scientific community has been heavily engaged in studying the grapevine response to climate change. Final goal is the identification of key genetic traits to be used in grapevine breeding and the setting of agronomic practices to improve climatic resilience. The increasing availability of transcriptomic studies, describing gene expression in many tissues and developmental, or treatment conditions, have allowed the implementation of gene expression compendia, which enclose a huge amount of information. The mining of transcriptomic data represents an effective approach to expand a known local gene network (LGN) by finding new related genes. We recently published a pipeline based on the iterative application of the PC-algorithm, named NES²RA, to expand gene networks in Escherichia coli and Arabidopsis thaliana. Here, we propose the application of this method to the grapevine transcriptomic compendium Vespucci, in order to expand four LGNs related to the grapevine response to climate change. Two networks are related to the secondary metabolic pathways for anthocyanin and stilbenoid synthesis, involved in the response to solar radiation, whereas the other two are signaling networks, related to the hormones abscisic acid and ethylene, possibly involved in the regulation of cell water balance and cuticle transpiration. The expansion networks produced by NES²RA algorithm have been evaluated by comparison with experimental data and biological knowledge on the identified genes showing fairly good consistency of the results. In addition, the algorithm was effective in retaining only the most significant interactions among the genes providing a useful framework for experimental validation. The application of the NES²RA to Vitis vinifera expression data by means of the BOINC-based implementation is available upon request (valter.cavecchia@cnr.it).

The effect of methyl jasmonate and light irradiation treatments on the stilbenoid biosynthetic pathway in Vitis vinifera cell suspension cultures

Grape stilbenes are a well-known family of plant polyphenolics that have been confirmed to have many biological activities in relation to health benefits. In the present study, we investigated the effect of methyl jasmonate (MeJA) elicitor at four different concentrations (25, 50, 100 and 200 μM) in combination or not with high-level light irradiation (10,000 LUX) on a cell line obtained from the pulp of Vitis vinifera cv. Shahani. Our results showed that the stilbene synthesis pathway is inhibited by high-light conditions. A concentration of 50 μM MeJA was optimum for efficient production and high accumulation of total phenolics and total flavonoids as well as total stilbenoids. Furthermore, we showed that there is a significant negative correlation between the production of these metabolites and cell growth. These data provide valuable information for the future scale-up of cell cultures for the production of these very high value compounds in bioreactor system.

Neofusicoccum parvum Colonization of the Grapevine Woody Stem Triggers Asynchronous Host Responses at the Site of Infection and in the Leaves

Grapevine trunk diseases cause important economic losses in vineyards worldwide. Neofusicoccum parvum, one of the most aggressive causal agents of the trunk disease Botryosphaeria dieback, colonizes cells and tissues of the grapevine wood, leading to the formation of an internal canker. Symptoms then extend to distal shoots, with wilting of leaves and bud mortality. Our aim was to characterize the transcriptional dynamics of grapevine genes in the woody stem and in the leaves during Neofusicoccum parvum colonization. Genome-wide transcriptional profiling at seven distinct time points (0, 3, and 24 hours; 2, 6, 8, and 12 weeks) showed that both stems and leaves undergo extensive transcriptomic reprogramming in response to infection of the stem. While most intense transcriptional responses were detected in the stems at 24 hours, strong responses were not detected in the leaves until the next sampling point at 2 weeks post-inoculation. Network co-expression analysis identified modules of co-expressed genes common to both organs and showed most of these genes were asynchronously modulated. The temporal shift between stem vs. leaf responses affected transcriptional modulation of genes involved in both signal perception and transduction, as well as downstream biological processes, including oxidative stress, cell wall rearrangement and cell death. Promoter analysis of the genes asynchronously modulated in stem and leaves during N. parvum colonization suggests that the temporal shift of transcriptional reprogramming between the two organs might be due to asynchronous co-regulation by common transcriptional regulators. Topology analysis of stem and leaf co-expression networks pointed to specific transcription factor-encoding genes, including WRKY and MYB, which may be associated with the observed transcriptional responses in the two organs.

Total Synthesis of Viniferifuran, Resveratrol-Piceatannol Hybrid, Anigopreissin A and Analogues - Investigation of Demethylation Strategies

Resveratrol-based natural products constitute a valuable source of unique compounds with diverse biological activities. In this report we investigate demethylation strategies to minimize formation of cyclized and dimerized products during the synthesis of viniferifuran and analogues. We found that boron trichloride/tetra-n-butylammonium iodide (BCl3/TBAI) is typically more effective than boron tribromide (BBr3). Based on these findings we carried out the first syntheses of dehydro-δ-viniferin, resveratrol-piceatannol hybrid and anigopreissin A. In addition, we have developed a short and efficient route to viniferifuran that was obtained in 13% yield over six steps.

Chemical Constituents from the Aerial Parts of Cyrtopodium paniculatum

We report the first phytochemical study of the neotropical orchid Cyrtopodium paniculatum. Eight new compounds, including one phenanthrene 1, one 9,10-dihydro-phenanthrene 2, one hydroxybenzylphenanthrene 3, two biphenanthrenes 4–5, and three 9,10 dihydrophenanthrofurans 6–8, together with 28 known phenolic compounds, mostly stilbenoids, were isolated from the CH₂Cl₂ extract of its leaves and pseudobulbs. The structures of the new compounds were established on the basis of extensive spectroscopic methods.

A comparative assessment of the cytotoxicity and nitric oxide reducing ability of resveratrol, pterostilbene and piceatannol in transformed and normal mouse macrophages

The present study investigated the pharmacological effects of three stilbenoids, resveratrol (RES), pterostilbene (PTR) and piceatannol (PIC), in transformed and normal macrophages. Our first aim was to comparatively assess the cytotoxicity of RES, PTR and PIC in unstimulated transformed mouse macrophages (RAW 264.7 cells) and primary peritoneal macrophages (PMs) harvested from both wild type and Nrf2 (nuclear factor erythroid 2-related factor 2)-deficient female mice. Our second aim was to investigate whether the inhibitory effect of RES, PTR and PIC on nitric oxide (NO) release from stimulated PMs depends on the status of the transcription factor Nrf2. The rationale for investigating Nrf2 status was based upon recent reports showing that certain compounds (sulforaphane and linalool) suppress LPS-induced inflammation in an Nrf2-dependent manner. Cell viability studies confirmed our prior work in unstimulated RAW 264.7 cells, with cytotoxic potency decreasing in the order of PTR > PIC > RES. Unstimulated PMs, regardless of Nrf2 status, were less sensitive to stilbenes, requiring at least a threefold higher stilbene concentration to inhibit cell viability, with cytotoxic potency again decreasing in the order of PTR > PIC > RES. In studies focused on our second aim, IC₅₀ values for NO inhibition (measured as [Formula: see text]) in wild type PMs were similar for all three stilbenes (∼10 μM). In Nrf2-deficient PMs, the IC₅₀ for NO inhibition by PIC did not change; however, a rightward shift in the concentration effect curve was observed for both RES and PTR, indicating a role for Nrf2 in the suppression of LPS-induced [Formula: see text] accumulation by these particular stilbenes.

New Monomeric Stilbenoids from Peanut (Arachis hypogaea) Seeds Challenged by an Aspergillus flavus Strain

Two new stilbene derivatives have been isolated from peanut seeds challenged by an Aspergillus flavus strain, along with chiricanine B, which has not been previously reported from peanuts, as well as a stilbenoid reported previously only as a synthetic product. The structures of these new putative phytoalexins were determined by analysis of (1)H and (13)C NMR, HRESIMS, MS(n), and UV data. The new stilbenoids were named arahypin-13 (21), arahypin-14 (22), and arahypin-15 (23). Together with other known bioactive peanut stilbenoids that were also produced in the challenged seeds, these new compounds may play a defensive role against invasive fungi.

Composition and Tissue-Specific Distribution of Stilbenoids in Grape Canes Are Affected by Downy Mildew Pressure in the Vineyard

Grape canes are byproducts of viticulture containing valuable bioactive stilbenoids including monomers and oligomers of E-resveratrol. Although effective contents in stilbenoids are known to be highly variable, the determining factors influencing this composition remain poorly understood. As stilbenoids are locally induced defense compounds in response to phytopathogens, this study assessed the impact of downy mildew infection during the growing season on the stilbenoid composition of winter-harvested grape canes. The spatial distribution between pith, conducting tissues, and cortex of E-piceatannol, E-resveratrol, E-ε-viniferin, ampelopsin A, E-miyabenol C, Z/E-vitisin B, hopeaphenol, and isohopeaphenol in grape canes from infected vineyards was strongly altered. In conducting tissues, representing the main site of stilbenoid accumulation, E-ε-viniferin content was higher and E-resveratrol content was lower. These findings suppose that the health status in vineyards could modify the composition of stilbenoids in winter-harvested grape canes and subsequently the potential biological properties of the valuable extracts.

Enhanced Production of Resveratrol, Piceatannol, Arachidin-1, and Arachidin-3 in Hairy Root Cultures of Peanut Co-treated with Methyl Jasmonate and Cyclodextrin

Peanut (Arachis hypogaea) produces stilbenoids upon exposure to abiotic and biotic stresses. Among these compounds, the prenylated stilbenoids arachidin-1 and arachidin-3 have shown diverse biological activities with potential applications in human health. These compounds exhibit higher or novel biological activities in vitro when compared to their nonprenylated analogues piceatannol and resveratrol, respectively. However, assessment of these bioactivities in vivo has been challenging because of their limited availability. In this study, hairy root cultures of peanut were induced to produce stilbenoids upon treatment with elicitors. Co-treatment with 100 μM methyl jasmonate (MeJA) and 9 g/L methyl-β-cyclodextrin (CD) led to sustained high levels of resveratrol, piceatannol, arachidin-1, and arachidin-3 in the culture medium when compared to other elicitor treatments. The average yields of arachidin-1 and arachidin-3 were 56 and 148 mg/L, respectively, after co-treatment with MeJA and CD. Furthermore, MeJA and CD had a synergistic effect on resveratrol synthase gene expression, which could explain the higher yield of resveratrol when compared to treatment with either MeJA or CD alone. Peanut hairy root cultures were shown to be a controlled and sustainable axenic system for the production of the diverse types of biologically active stilbenoids.

Biosynthetic origin of E-resveratrol accumulation in grape canes during postharvest storage

Grape canes are vineyard waste products containing valuable phytochemicals of medicine and agriculture interest. Grape canes storage is critical for the accumulation of these bioactive compounds. In the present study, we investigated the changes in stilbenoid phytochemical composition during grape cane storage and the influence of the temperature on final concentrations. A strong increase in the concentration of the monomer E-resveratrol (approximately 40-fold) was observed during the first 6 weeks of storage at 20 °C in eight different grape varieties without any change in oligomer concentrations. The E-resveratrol accumulation was temperature-dependent with an optimal range at 15-20 °C. A 2 h heat-shock treatment aiming at protein denaturation inhibited E-resveratrol accumulation. The constitutive expression of key genes involved in the stilbene precursor biosynthesis along with an induction of stilbene synthase (STS) expression during the first weeks of storage contribute to a de novo biosynthesis of E-resveratrol in pruned wood grapes.

Analysis of the phenolic composition of fungus-resistant grape varieties cultivated in Italy and Germany using UHPLC-MS/MS

The phenolic composition of grape berries grown in Italy (Cabernet Cortis, Johanniter, Solaris, Phoenix, and Regent) and in Germany (Regent and Phoenix) was analyzed using two complementary LC-MS/MS (Liquid Chromatography - Tandem Quadrupole Mass Spectrometry) methods. These five cultivars belong to fungus-resistant grape varieties (PIWI) and little is known about their phenolic profile, although phenolics such as phytoalexins have been recognized, playing a key role in the resistance mechanism. A triple quadruple mass spectrometer detector was used for both identification and quantification, and analytical tools from untargeted metabolomics were applied to check and control the quality of the results. Specifically, biological, technical, and instrumental replications were included in order to study the variability at different levels. The results allowed tuning of the sampling protocol and provided a rich phenolic metabolite profile for the aforementioned PIWI varieties, as compared with Vitis vinifera cultivars, especially in the class of stilbenes.

Utilization of adjuvant arthritis model for evaluation of new approaches in rheumatoid arthritis therapy focused on regulation of immune processes and oxidative stress

As a number of disease-modifying anti-rheumatic drugs often have side effects at high doses and/or during long-term administration, increased efficacy without increased toxicity is expected for combination therapy of rheumatoid arthritis (RA). The safety of long-term therapy of RA is very important as patients with RA are usually treated for two or more decades. This experimental overview is focused on some promising substances and their combinations with the standard antirheumatic drug – methotrexate (Mtx) for treatment of rheumatoid arthritis. The adjuvant arthritis model in Lewis rats was used for evaluation of antiinflammatory efficacy of the substances evaluated. Mtx was administered in the oral dose of 0.3 mg/kg b.w. twice a week. Natural and synthetic antioxidants were administered in the daily oral dose of 20 mg/kg b.w for coenzyme Q₁₀ (CoQ₁₀), 150 mg/kg b.w for carnosine (Carn), 15 mg/kg b.w. for stobadine dipalmitate (Stb) and its derivative SMe1.2HCl (SMe1), and 30 mg/kg b.w. for pinosylvin (Pin) or pterostilbene (Pte). Mtx in the oral dose of 0.4 mg/kg b.w. twice a week was combined with Pin in the oral daily dose of 50 mg/kg b.w. Clinical (hind paw volume – HPV), biochemical (activity of GGT in joint and level of TBARS in plasma), and immunological (IL-1 in plasma) parameters were assessed. Our results achieved with different antioxidants in monotherapies showed a reduction of oxidative stress in adjuvant arthritis independently of the chemical structure of the compounds. Pin was the most effective antioxidant tested in decreasing HPV. All combinations tested showed a higher efficacy in affecting biochemical or immunological parameters than Mtx administered in monotherapy. The findings showed the benefit of antioxidant compounds for their use in combination therapy with methotrexate.