Grape Resveratrol Research Articles

Retaining Resveratrol Content in Berries and Berry Products with Agricultural and Processing Techniques: Review

Resveratrol is a natural compound that can be found in red wine, grapes, and berries. It has attracted attention due to its potential health benefits. The aim of this review was to align ways of retaining resveratrol contents in berries and products made of berries, and to show which agricultural and processing techniques can maximize the content in the berries and their products and how this can be achieved. The scientific literature has revealed that resveratrol concentration in berries and berry-derived products varies significantly depending on the source and the processing techniques applied. Resveratrol content can range from 0.03–0.06 mg/kg in blueberries to 5–10 mg/kg in grape skins. Agricultural techniques such as controlled water stress (e.g., increasing resveratrol in grapes to 8.3–11.5 mg/kg), optimal sun exposure (e.g., enhancing blueberries to 1.5–2.1 mg/kg), balanced nutrient management, and selecting high-resveratrol cultivars (e.g., up to 15 mg/kg in certain grapes) can substantially increase resveratrol content. Processing methods like cold pressing, centrifugation, ultrafiltration, and freeze-drying are effective in preserving resveratrol levels, while traditional pasteurization tends to reduce its concentration. For instance, high-temperature short-time pasteurization can reduce resveratrol in juice from 1.5 mg/kg to 0.8 mg/kg, whereas cold pressing retains more resveratrol (1.5 mg/kg to 1.4 mg/kg). By optimizing these agricultural and processing techniques, manufacturers can enhance the resveratrol content in berry-derived products, meeting the growing consumer demand for health-enhancing natural products and supporting a healthier society. This approach aligns with the commitment to overcoming the technical challenges associated with resveratrol use, ensuring its potential is fully realized in both health-related and non-health-related applications.

Phenolic acids and polydatin of grape and products of its processing

The paper established that in the fruits of red grapes and in the products of its processing, the main phenolic acids are not chlorogenic acids (the acylation product of quinic acid by caffeic one), as indicated in a number of publications, but caftaric acid (the acylation product of tartaric acid by caffeic one) and coutaric acid (the acylation product of tartaric acid by p-coumaric one). For chromatographic analysis of the studied samples, the stationary phase Symmetry C18 and the mobile phases of the “acetonitrile – 10 vol.% of HCOOH-water” system were chosen, being convenient for determining grape anthocyanins. It was shown that caftaric acid in all studied mobile phase compositions is completely separated from coutaric acid and from three isomeric monocaffeoylquinic acids (3-caffeoylquinic, 4-caffeoylquinic and 5-caffeoylquinic), i.e. there is no confusion between the retention times of these acids. But for chromatography, mobile phase compositions should be selected in which there is no co-elution of any of these acids with delphinidin-3-glucoside, which is usually present in extracts, juices and wines. Complete separation of these components is possible both with a relatively low acetonitrile content (less than 6 vol. %) in the mobile phase, and with a relatively high (at least 8.5 vol. %) as well. This made it possible to propose a gradient elution option for separating all compounds of interest. A gradient mode was needed to elute all anthocyanins and associated extractives from the column. It turned out that the proposed separation conditions were favorable for the detection of polydatin (one of the isomeric glucosides of resveratrol). This made it possible to establish another common misconception, according to which it is claimed that resveratrol (and not its glucoside) is one of the most important biologically active substances in grapes. Under the proposed conditions, much more strongly retained resveratrol coelutes with one of the acylated anthocyanins, but analysis of the areas of the corresponding peaks indicates that polydatin is the dominant form of resveratrol in grapes

Botrytis cinerea identifies host plants via the recognition of antifungal capsidiol to induce expression of a specific detoxification gene.

The gray mold pathogen Botrytis cinerea has a broad host range, causing disease in >400 plant species, but it is not known how this pathogen evolved this polyxenous nature. Botrytis cinerea can metabolize a wide range of phytoalexins, including the stilbenoid resveratrol in grape, and the sesquiterpenoids capsidiol in tobacco and rishitin in potato and tomato. In this study, we analyzed the metabolism of sesquiterpenoid phytoalexins by B. cinerea. Capsidiol was dehydrogenated to capsenone, which was then further oxidized, while rishitin was directly oxidized to epoxy- or hydroxyrishitins, indicating that B. cinerea has separate mechanisms to detoxify structurally similar sesquiterpenoid phytoalexins. RNA-seq analysis revealed that a distinct set of genes were induced in B. cinerea when treated with capsidiol or rishitin, suggesting that B. cinerea can distinguish structurally similar phytoalexins to activate appropriate detoxification mechanisms. The gene most highly upregulated by capsidiol treatment encoded a dehydrogenase, designated Bccpdh. Heterologous expression of Bccpdh in a capsidiol-sensitive plant symbiotic fungus, Epichloë festucae, resulted in an acquired tolerance of capsidiol and the ability to metabolize capsidiol to capsenone, while B. cinerea Δbccpdh mutants became relatively sensitive to capsidiol. The Δbccpdh mutant showed reduced virulence on the capsidiol producing Nicotiana and Capsicum species but remained fully pathogenic on potato and tomato. Homologs of Bccpdh are found in taxonomically distant Ascomycota fungi but not in related Leotiomycetes species, suggesting that B. cinerea acquired the ancestral Bccpdh by horizontal gene transfer, thereby extending the pathogenic host range of this polyxenous pathogen to capsidiol-producing plant species.

Changes in the Content and Bioavailability of Onion Quercetin and Grape Resveratrol During In Vitro Human Digestion.

We investigated the effects of in vitro human digestion on the content and bioavailability of onion quercetin and grape resveratrol caused by the composition of saliva or gastric, duodenal, or bile juice. We observed the digestibility of extracted onion quercetin and grape resveratrol, respectively, in the small intestine of the in vitro human digestion system. By liquid chromatography–mass spectroscopy, we found that the degradation of quercetin and resveratrol was influenced by small intestine digestion. Before and after in vitro human digestion, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of homogenized water- and ethanol-extracted grapes were higher than those of onion extracts. DPPH radical scavenging activity in both quercetin and resveratrol was decreased by in vitro digestion. These results will improve our understanding of how human digestion influences the contents and free radical scavenging activities of quercetin and resveratrol.

A Systematic Review on Natural Antioxidant Properties of Resveratrol

Polyphenols, including anthocyanins, flavonoids and stilbenes, which constitute one of the most abundant and ubiquitous groups of plant metabolites, are an integral part of the human diet. Resveratrol (3,5,4'-trihydroxystilbene), a naturally occurring polyphenol produced by some plants as a self-defence agent, has an antifungal activity. Resveratrol has been found in some plants (such as grapevine, pine and peanuts) and is considered to have beneficial effects also on human health. The number of studies on resveratrol greatly increased in PubMed database since 1997, after the anticancer effect of this molecule was first reported. The interest in resveratrol in grape was originally sparked by epidemiological studies indicating an inverse relationship between long-standing moderate consumption of red wine and the risk of coronary heart disease; this effect has been ascribed to resveratrol, which possesses diverse biochemical and physiological properties, including antiplatelet and anti-inflammatory proprieties, and provides a wide range of health benefits ranging from chemoprevention to cardioprotection. Recently, resveratrol has been described as an anti-aging compound. The consumption of resveratrol (red wine) together with a Mediterranean diet or a fast-food meal (“McDonald'sMeal”) had a positive impact on oxidized (ox-) LDL and on the expression of oxidative and inflammatory genes. Therefore, this review summarized the most important scientific data about healing and preventive potential of resveratrol, acting as cardioprotective, neuroprotective, chemopreventive and antioxidant agent.

Antiadipogenic Effects and Mechanisms of Combinations of Genistein, Epigallocatechin-3-Gallate, and/or Resveratrol in Preadipocytes

Natural bioactive compounds are considered an excellent alternative strategy for developing effective, safe, and cost-effective antiobesity agents. The aim of this study was to investigate if combinations of soy bean genistein (G), green tea epigallocatechin-3-gallate (E), and/or grape resveratrol (R) at low dosages synergistically inhibit preadipocyte differentiation both in 3T3-L1 cells and human primary preadipocytes (HPAs). Our results show that combinations of G, E, and/or R additively inhibited preadipocyte differentiation (39-56% of control) both in 3T3-L1 cells at 30 μM and HPAs at 15 μM, while the individual compounds have no antiadipogenic effect at the selected concentrations. We also observed similar patterns that combinations of G, E, and/or R additively reduced protein expressions of peroxisome proliferator-activated receptor gamma (PPAR-γ) and CCAAT binding proteins alpha (C/EBP-α), the two key preadipocyte differentiation regulators, both in differentiated 3T3-L1 cells and HPAs. Moreover, combined G, E, and/or R attenuated protein expressions of fatty acid binding protein 4 and perilipin, two PPAR-γ/C/EBP-α downstream molecules in fat drop development in a very similar pattern, in inhibiting differentiation in preadipocytes. This combined antiadipogenic effect of G + E + R is additive, not synergistic according to our results and the Median-Effect Principle. In addition, we found that a lower concentration (15 μM) of G, E, and/or R is required in HPAs than the concentration (30 μM) needed in 3T3-L1 cells, to exert the combined antiadipogenic effect. These data suggest that combinations of G, E, and/or R intake or soy bean, green tea, and/or grape simultaneous consumption may prevent obesity in human being.

Isolation and identification of resveratrol-producing endophytes from wine grape Cabernet Sauvignon.

ObjectivesObtain endophyte strains with effective resveratrol production from superior grapevine variety Cabernet Sauvignon in Xinjiang and determine related taxonomic position of the strain.ResultsSeventy-three strains of endophytes, including 23 strains of bacteria, 14 ones of actinomycetes, 24 fungus and 12 yeasts, were isolated, respectively. The distribution law of endophytes was spring (30.14 %) = summer (30.14 %) < autumn (39.73 %) in different seasons, while the fruit (12.33 %) < leaf (20.55 %) < stem (32.88 %) < root (34.25 %) in different tissues and organs. From the 36 strains of endophytic fungi isolated, seven strains producing polyphenols were screened by ferric chloride–potassium ferricyanide color reaction. C2J6, stable genetic properties producing highly 1.48 mg L−1 of resveratrol, was identified as Aspergillus niger by 26S rDNA-ITS sequence analysis after thin-layer chromatography sieve analysis, ultra violet wavelength scanning and high performance liquid chromatography, respectively.ConclusionsThere were the certain number and kinds of endophytes in the various tissues of Cabernet Sauvignon, which, to a certain extent, reflected the biological diversity of plant endophytes. The fact that the fungus C2J6 producing resveratrol in grape was acquired attested the special ability of the endophytes to produce the same or similar bioactive substances as the host plants.

Resveratrol Synthesis under Natural Conditions and after Ultraviolet-C Irradiation in Grape Leaves at Different Leaf Developmental Stages

The biosynthesis and accumulation of resveratrol in grape may be regulated by genetic and environmental factors [i.e., ultraviolet-C (UV-C) irradiation]. However, there is a lack of research on the biosynthesis and accumulation of resveratrol in grape leaves responding to UV-C irradiation at sequential developmental stages. In this study, leaf resveratrol concentration during different developmental stages of three grape cultivars, Jingxiu, Beifeng, and MRH3, under natural conditions, and of ‘Beifeng’ leaves exposed to UV-C irradiation was investigated. Results showed that resveratrol synthesis was related to the developmental stages under natural conditions. In young leaves, resveratrol concentration was low, but it increased continuously during leaf development, mainly as piceid forms. UV-C irradiation greatly stimulated resveratrol synthesis in ‘Beifeng’ leaves, and young leaves at 20 days were most sensitive to the irradiation. The total resveratrol in the skin of UV-C irradiated berries is about 19 times higher than that of the control, mainly in the forms of trans-resveratrol (trans-res)/cis-resveratrol (cis-res). These results provide a basis for increasing resveratrol concentration by artificial means.

Differential response of the biosynthesis of resveratrols and flavonoids to UV-C irradiation in grape leaves

Resveratrols and flavonoids have important beneficial roles in plants and to humans. The grape family (Vitaceae) is one of several families that can biosynthesise both resveratrols and flavonoids. Previous research has shown that UV-C may induce the biosynthesis of resveratrols in the fruit of grape. But little is known about the UV-C-induced biosynthesis of resveratrols and flavonoids in grape leaves. This study demonstrated that the biosynthesis of resveratrol in grape leaves strongly increased in response to UV-C irradiation. The largest contribution to total resveratrols was trans-resveratrol. The expression of related genes, including PAL, C4H, 4CL and STS, increased and peaked 6–12 h after treatment, earlier than the peak of total resveratrol. In contrast, total flavonoid content and the expression of the key gene CHS was not affected by UV-C radiation, staying at a low level after UV-C irradiation. In summary, there is a differential response to UV-C radiation for the biosynthesis of stilbenes and flavonoids in grape leaves.

High Levels of Resveratrol in Grapes Cultivated at High Altitude Valleys in Bolivia

Trans-resveratrol, total antioxidant capacity (TAC), and total phenolic compounds were assessed in Bolivian grape cultivars collected at high altitude valleys. The TAC of the grapes ranged from 0.8 to 22 μmol Trolox equivalents/g dry matter determined by 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid), and from 0.6 to 10 determined by the ferric reduction antioxidant power. In the present study, we observed that under certain conditions trans-resveratrol levels in Bolivian grapes are 10-fold higher than the reported data from the literature. Additionally, the temporal evolution in three different solar ultraviolet-B radiation levels was carried out to understand their effect on the oxidative processes.

Individual and Combined Effects of CaCl2 and UV–C on the Biosynthesis of Resveratrols in Grape Leaves and Berry Skins

The individual and combined effects of calcium chloride (CaCl2) and ultraviolet C (UV-C) light on the synthesis of resveratrol in grape leaves and berry skins were investigated. Results showed that all treatments could increase leaf resveratrol contents at least about 5 times, but the combination treatment was the most efficient. Moreover, compared with UV-C treatment, the combination treatment delayed the decline of resveratrol contents. The expression levels of phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), coumaroyl-CoA ligase (4CL), and stilbene synthase (STS) and 3-O-β-glycosyltransferases, which are related to the synthesis of resveratrol, increased in response to these treatments, paralleling the change in resveratrol content. All treatments also induced the biosynthesis of resveratrol in berry skins at room temperature. The berries of these treatments held at room temperature for 1 day were further stored under low temperature (-1 ± 0.5 °C, RH 95%) for 27 days, and the results showed that all treatments continuously increased berry skin resveratrol content, with the combination treatment being most efficient. During cold storage, resveratrol content remained at high levels and reached a maximum (about 247.7 μg/g FW) at 13 days, then showed a slight decline, though it remained high by the end of storage. Berry firmness and total soluble solids content showed slight changes during cold storage, but there were no differences among the treatments. Thus, the combination treatment of CaCl2 and UV-C could be an efficient method for increasing resveratrol content of table grapes during storage under low temperature. This would be potentially beneficial for producing functional fruits.

Beneficial Effects of Grape Resveratrol on Serum Adiponectin and Inflammation: Clinical Trial in Patients with Stable Coronary Artery Disease

Coronary artery disease (CAD) is a leading cause of heart failure on a world-wide basis [1–3]. The epidemic proportion of CAD is increasing worldwide irrespective of gender [3, 4]. Coronary artery disease is associated with lower oxygen supply and demand ratio due to abnormalities of the coronary vasculature. The coronary arteries supply oxygenated blood to the heart muscle and due to the process of atherosclerosis leading to plaque rupture and acute coronary syndrome, myocardial blood supply is compromised leading to myocardial ischemia/infarction and heart failure [5, 6]. Many clinicians and cardiovascular researchers recognize the clinical as well as molecular pathophysiological basis of coronary artery disease. There are many research groups actively searching the intervention strategies to prevent CAD. Many of these studies confirmed that CAD can be favorably prevented by lifestyle modifications (dietary control, exercise and smoking cessation) and pharmacotherapy [7]. However current pharmacotherapies which include anti-platelet drugs (aspirin, clopidogrel and prasugrel), betablockers, statin therapy and ACE inhibitors, are suboptimal [8, 9]. Resveratrol is a polyphenolic flavonoid with phytoalexin properties and has several pleotropic effects on cardiovascular function such as anti-oxidant and antiinflammatory effects and metabolic modulation (Fig. 1) [10–14]. However, these studies were performed in animal models and clinical evidence of the therapeutic effectiveness of resveratrol in humans is limited. In this issue of Cardiovascular Drugs and Therapy, Tome-Carneiro et al. investigate and analyze the beneficial pleotropic effects of 1 year dietary intervention with resveratrol containing grape extract (U.V treated grapes) on inflammatory as well as fibrinolytic status in patients with stable coronary artery disease [15]. Naturally the content of resveratrol in dietary sources is very low and the consumption of these natural food items (wine and grapes) does not exert beneficial effects in the prevention of many cardiovascular complications. As such Tome-Carneiro et al. used a novel resveratrol rich grape extract (GE-RES) obtained from U.V treated grapes (GE-RSE) in dietary intervention of CAD patents. Resveratrol is a potent therapeutical phytochemical with cardioprotective effects [10]. It targets and modulates pathological death signals and can protect patients by preventing several cardiovascular risk factors from causing endothelial dysfunction, inflammation, atherosclerotic plaque formation and dyslipidemia [1]. Inflammation and atherogenesis are the initial manifestations in coronary artery disease, which is associated with focal S. K. Das :V. B. Patel :G. Y. Oudit Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, Canada

Determination of trans-resveratrol in grape seed by coupling liquid extraction with micellar electrokinetic chromatography

A new method for the determination of trans-resveratrol in grape seed was developed by coupling liquid extraction (LE) and micellar electrokinetic chromatography (MEKC). LE was employed for sample preparation and MEKC for analytical separation. The solvent used for LE was ethyl acetate and the buffer for MEKC consisted of 25 mM borate containing 25 mM sodium dodecyl sulfate (SDS) and 2.5 mM sodium salt sulfated-β-cyclodextrin at pH 9.0. The limit of detection (S/N = 3) was found to be 4.62 × 10−7 g ml−1. Linear regression of peak area versus concentration of resveratrol was checked with the r squared being greater than 0.99 for resveratrol at a concentration range of 9.25 × 10−6 g ml−1 to 4.63 × 10−2 g ml−1. The recoveries were over 90% for the determination of resveratrol in grape seed samples. The method developed can be an attractive alternative to the HPLC methods reported in the literature for the determination of resveratrol in grape seed with the advantages of a reduction of analysis time and operation cost. To the best of our knowledge, this is the first report on the determination of resveratrol in grape seed based on coupling LE and MEKC.

Grape resveratrol increases serum adiponectin and downregulates inflammatory genes in peripheral blood mononuclear cells: a triple-blind, placebo-controlled, one-year clinical trial in patients with stable coronary artery disease.

PurposeThe grape and wine polyphenol resveratrol exerts cardiovascular benefits but evidence from randomized human clinical trials is very limited. We investigated dose-depending effects of a resveratrol-containing grape supplement on stable patients with coronary artery disease (CAD) treated according to currently accepted guidelines for secondary prevention of cardiovascular disease.MethodsIn a triple-blind, randomized, placebo-controlled, one-year follow-up, 3-arm pilot clinical trial, 75 stable-CAD patients received 350 mg/day of placebo, resveratrol-containing grape extract (grape phenolics plus 8 mg resveratrol) or conventional grape extract lacking resveratrol during 6 months, and a double dose for the following 6 months. Changes in circulating inflammatory and fibrinolytic biomarkers were analyzed. Moreover, the transcriptional profiling of inflammatory genes in peripheral blood mononuclear cells (PBMCs) was explored using microarrays and functional gene expression analysis.ResultsAfter 1 year, in contrast to the placebo and conventional grape extract groups, the resveratrol-containing grape extract group showed an increase of the anti-inflammatory serum adiponectin (9.6 %, p = 0.01) and a decrease of the thrombogenic plasminogen activator inhibitor type 1 (PAI-1) (−18.6 %, p = 0.05). In addition, 6 key inflammation-related transcription factors were predicted to be significantly activated or inhibited, with 27 extracellular-space acting genes involved in inflammation, cell migration and T-cell interaction signals presenting downregulation (p < 0.05) in PBMCs. No adverse effects were detected in relation to the study products.ConclusionsChronic daily consumption of a resveratrol-containing grape nutraceutical could exert cardiovascular benefits in stable-CAD patients treated according to current evidence-based standards, by increasing serum adiponectin, preventing PAI-1 increase and inhibiting atherothrombotic signals in PBMCs.Electronic supplementary materialThe online version of this article (doi:10.1007/s10557-012-6427-8) contains supplementary material, which is available to authorized users.

One-Year Consumption of a Grape Nutraceutical Containing Resveratrol Improves the Inflammatory and Fibrinolytic Status of Patients in Primary Prevention of Cardiovascular Disease

The search for complementary treatments in primary prevention of cardiovascular disease (CVD) is a high-priority challenge. Grape and wine polyphenol resveratrol confers CV benefits, in part by exerting anti-inflammatory effects. However, the evidence in human long-term clinical trials has yet to be established. We aimed to investigate the effects of a dietary resveratrol-rich grape supplement on the inflammatory and fibrinolytic status of subjects at high risk of CVD and treated according to current guidelines for primary prevention of CVD. Seventy-five patients undergoing primary prevention of CVD participated in this triple-blinded, randomized, parallel, dose-response, placebo-controlled, 1-year follow-up trial. Patients, allocated in 3 groups, consumed placebo (maltodextrin), a resveratrol-rich grape supplement (resveratrol 8 mg), or a conventional grape supplement lacking resveratrol, for the first 6 months and a double dose for the next 6 months. In contrast to placebo and conventional grape supplement, the resveratrol-rich grape supplement significantly decreased high-sensitivity C-reactive protein (-26%, p = 0.03), tumor necrosis factor-α (-19.8%, p = 0.01), plasminogen activator inhibitor type 1 (-16.8%, p = 0.03), and interleukin-6/interleukin-10 ratio (-24%, p = 0.04) and increased anti-inflammatory interleukin-10 (19.8%, p = 0.00). Adiponectin (6.5%, p = 0.07) and soluble intercellular adhesion molecule-1 (-5.7%, p = 0.06) tended to increase and decrease, respectively. No adverse effects were observed in any patient. In conclusion, 1-year consumption of a resveratrol-rich grape supplement improved the inflammatory and fibrinolytic status in patients who were on statins for primary prevention of CVD and at high CVD risk (i.e., with diabetes or hypercholesterolemia plus ≥1 other CV risk factor). Our results show for the first time that a dietary intervention with grape resveratrol could complement the gold standard therapy in the primary prevention of CVD.

Evaluation of renal protective effects of the green-tea (EGCG) and red grape resveratrol: role of oxidative stress and inflammatory cytokines

Epigallocatechin-gallate (EGCG) and resveratrol (RSVL) are two of the most promising natural medicines. We verified their capacity to ameliorate cisplatin (CP)-induced disruption of renal glomerular filtration rate (GFR) in rats, and sought the mediatory involvement of lipid peroxidation (malondialdehyde [MDA]-level) and inflammatory cytokine (TNF-α) therein. CP (10 mg kg−1), a single i.p. dose, disrupted GFR (11-fold-rise in proteinuria, 2–5-fold rise in serum creatinine/urea levels) after 7 days, and killed all animals after 10 days. Kidney-homogenates from CP-treated rats displayed higher MDA and TNF-α, but lower reduced-glutathione (GSH) levels. Rats treated with EGCG (50 mg kg−1, but not 25 mg kg−1) had no fatalities and showed significantly-recovered GFR; while their kidney-homogenates had markedly reduced MDA, TNF‐α and enhanced GSH levels at 7 days. Conversely, RSVL or quercetin (25, 50 mg kg−1) neither improved GFR nor reduced (MDA)/TNF-α levels after 7 days. Resuming treatment with 50 mg kg−1 for 10 days rescued only 25% of animals (p > 0.05). Correlation studies showed a significant association between creatinine level, and each of MDA (r = 0.91), GSH (r = −0.87), and TNF-α (0.91). The study showed for the first time that EGCG, unlike RSVL, can protect against CP-induced nephrotoxicity. At the molecular level, CP triggers a high level of oxidative stress and systemic inflammation, events that were all abrogated with EGCG; better than RSVL or quercetin.

On the Use of the Own Plant's Defence Compounds to Maintain the Post-Harvest Fruit Quality

This work demonstrates that the own plant defence compounds, like resveratrol in grapes, can be used as a natural and ecological alternative to chemical pesticides. An extract from vine leaves was used to maintain the quality of post-harvested grapes. Specifically, an extract (95% water and 5% ethanol) of such leaves was prepared and, subsequently, different bunches of grapes were immersed in it. The same number of bunches received either water or ethanol (5%) treatment, being both used as blank. Remarkably, on the 14th day after the beginning of the treatment the extract treated grapes, always maintained at room temperature, showed no sign of physical deterioration. In contrast, the two blank samples, i.e.: the water or ethanol treated bunches appeared dehydrated, infected and deteriorated. Furthermore, the external application of the leaf's extract does not modify sensorial, biochemical and nutritional properties of the fruits. The beneficial effects of trans-resveratrol, such as anticancer, antiviral, neuroprotective, antiaging and anti-inflamatory support further the use of this natural compound instead of hazardous synthetic pesticides. Therefore, this study represents a step towards the development of new protocols to maintain the post-harvest fruit quality without resorting to chemical pesticides.

A review of the content of the putative chemopreventive phytoalexin resveratrol in red wine

Resveratrol, a naturally occurring compound of various fruits such as grapes, is thought to possess chemopreventive properties. The levels of resveratrol in grapes and grape products including wine, varies from region to region and from one year to another. This paper reviews the resveratrol content in red wine based on relevant published data. Red wine contains an average of 1.9 ± 1.7 mg trans-resveratrol/l (8.2 ± 7.5 μM), ranging from non-detectable levels to 14.3 mg/l (62.7 μM) trans-resveratrol. In general, wines made from grapes of the Pinot Noir and St. Laurent varieties showed the highest level of trans-resveratrol. No region can be said to produce wines with significantly higher level of trans-resveratrol than all other regions. Levels of cis-resveratrol follow the same trend as trans-resveratrol. The average level of trans-resveratrol-glucoside ( trans-piceid) in a red wine may be as much as 29.2 mg/l (128.1 μM), i.e., three times that of trans-resveratrol.

Effects of dietary chemopreventive phytochemicals on P-glycoprotein function

The effects of dietary phytochemicals on P-glycoprotein function were investigated using human multidrug-resistant carcinoma KB-C2 cells and the fluorescent P-glycoprotein substrates daunorubicin and rhodamine 123. The effects of natural chemopreventive compounds, capsaicin found in chilli peppers, curcumin in turmeric, [6]-gingerol in ginger, resveratrol in grapes, sulforaphane in broccoli, 6-methylsulfinyl hexyl isothiocyanate (6-HITC) in Japanese horseradish wasabi, indole-3-carbinol (I3C) in cabbage, and diallyl sulfide and diallyl trisulfide in garlic, were examined. The accumulation of daunorubicin in KB-C2 cells increased in the presence of capsaicin, curcumin, [6]-gingerol, and resveratrol in a concentration-dependent manner. The accumulation of rhodamine 123 in KB-C2 cells was also increased, and the efflux of rhodamine 123 from KB-C2 cells was decreased by these phytochemicals. Sulforaphane, 6-HITC, I3C, and diallyl sulfide and diallyl trisulfide had no effect. These results suggest that dietary phytochemicals, such as capsaicin, curcumin, [6]-gingerol, and resveratrol, have inhibitory effects on P-glycoprotein and potencies to cause drug–food interactions.

Resveratrol modulates apoptosis and oxidation in human blood mononuclear cells.

We examined the effect of resveratrol (RS), a nonflavonoid polyphenolic phytoalexin found in grapes and red wine, and RS coincubated with the oxidant 2-deoxy-D-ribose (dR), on apoptosis and on the oxidative metabolic status of normal human peripheral blood mononuclear cells (PBMNCs) isolated ex vivo from healthy donors. Apoptosis was measured by changes of membrane permeability to propidium iodide (PI), plasma membrane exposure of phosphatidylserine (PS) and intracellular caspase activity. Oxidative status was assessed by recording the intracellular glutathione concentration (GSH), the activities of the enzymes y-glutamyltransferase (y-GT) and glutathione-S-transferase (GST), and intracellular lipid peroxidation (MDA). Neither apoptotic nor oxidative parameters were affected by culturing PBMNCs in medium containing RS up to 20 micro M for 5 days, while the frequency of cells with intermediate permeability to PI (17% +/- 5) increased at 50 micro M of RS. Thus resveratrol was slightly toxic, but there was little apoptosis in these cells. Peripheral blood mononuclear cells were also grown first in medium plus RS for 24 h and then for 96 h in medium containing RS plus 10 mM of dR, an oxidant sugar that is apoptogenic for human lymphocytes. The apoptotic changes triggered by dR were counteracted by the phytoalexin in a dose-dependent manner, but RS activity was absent at the lowest concentration (5 micro M) and significantly reduced at the highest concentration used (50 micro M). In PBMNCs coincubated with 20 micro M of RS and 10 mM of dR the antioxidant effect of RS manifested with a significant reduction of caspases-3, -8, y-GT, GST activities and MDA content. Peripheral blood mononuclear cells acquire antioxidant capacity when treated with RS. Grape resveratrol may make a useful dietary supplement for minimizing oxidative injury in immune-perturbed states and human chronic degenerative diseases.