Role of the variety and some environmental factors on grape stilbenes

V. vinifera L. 'Barbera', 'Croatina', 'Malvasia di Candia aromatica', growing in the Piacenza viticultural area (North-West Italy) at four elevations (150, 240, 320, 420 m a.s.l.), were tested at harvest for grape stilbene (trans-resveratrol, trans-piceid, cis-piceid) synthesis over three years (2000-2002). Meteorological data were recorded, as well as vine production and fruit quality parameters. The most significant findings were:trans-piceid was the most abundantly produced stilbene compound (103 μg·kg-1 berry FW), while trans-resveratrol was the least produced (57 μg·kg-1 berry FW);'Barbera' and 'Croatina' had similar trans-resveratrol berry levels (71 μg·kg-1 berry FW and 76 μg·kg-1 berry FW respectively), higher than 'Malvasia di Candia aromatica' (24 μg·kg-1 berry FW);'Barbera' had the highest trans-piceid and cis-piceid concentrations (235 and 136 μg·kg-1 berry FW, respectively) while 'Malvasia di Candia aromatica' had the lowest levels (13 and 1 μg·kg-1 berry FW, respectively);stilbenes increased with elevation up to 320 m, while decreasing at the highest altitude;the vintage year only significantly affected the cis-piceid berry concentration which was positively related to the relative humidity at the end of ripening, and negatively related to degree-days at the end of ripening.

Stability and Photoisomerization of Stilbenes Isolated from the Bark of Norway Spruce Roots

Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce (Picea abies L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent light induce trans to cis isomerisation via intramolecular cyclization. So far, the characterizations of possible new compounds derived from trans-stilbenes under UV light exposure have been mainly tentative based only on UV or MS spectra without utilizing more detailed structural spectroscopy techniques such as NMR. The objective of this work was to study the stability of biologically interesting and readily available stilbenes such as astringin and isorhapontin and their aglucones piceatannol and isorhapontigenin, which have not been studied previously. The effects of fluorescent and UV light and storage on the stability of trans stilbenes were assessed and the identification and characterisation of new compounds formed during our experiments were carried out by chromatographic (HPLC, GC) and spectroscopic techniques (UV, MS, NMR). The stilbenes undergo a trans to cis isomerisation under extended UV irradiation by intramolecular cyclisation (by the formation of a new C-C bond and the loss of two hydrogens) to phenanthrene structures. The characterised compounds are novel and not described previously

A Focused Multiple Reaction Monitoring (MRM) Quantitative Method for Bioactive Grapevine Stilbenes by Ultra-High-Performance Liquid Chromatography Coupled to Triple-Quadrupole Mass Spectrometry (UHPLC-QqQ)

Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion. Due to this relevance, highly-specific qualitative and quantitative methods of analysis are necessary to accurately analyze stilbenes in different matrices derived from grapevine. Here, we developed a rapid, sensitive, and specific analysis method using ultra-high-performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ) in MRM mode to detect and quantify five grapevine stilbenes, trans-resveratrol, trans-piceid, trans-piceatannol, trans-pterostilbene, and trans-ε-viniferin, whose interest in relation to human health is continuously growing. The method was optimized to minimize in-source fragmentation of piceid and to avoid co-elution of cis-piceid and trans-resveratrol, as both are detected with resveratrol transitions. The applicability of the developed method of stilbene analysis was tested successfully in different complex matrices including cellular extracts of Vitis vinifera cell cultures, reaction media of biotransformation assays, and red wine.A.M.-M. acknowledges a grant from Conselleria d’Educacio, Cultura I Sport de la Generalitat Valenciana (FPA/2013/A/074). This work has been supported by grants from University of Alicante (VIGROB-105), the Spanish Ministry of Economy and Competitiveness (BIO2014-51861-R), and European funds for Regional development (FEDER)

Analytical Examination of Human and Phytoestrogens

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Elicitor-induced resveratrol production in cell cultures of different grape genotypes (Vitis spp.)

Higher plants synthesize secondary metabolites in response to abiotic and biotic stress. Liquid cell culture may be a useful tool for studying phytoalexin biosynthesis during plant interaction with pathogens. Dimethyl-β-cyclodextrin (DIMEB), an oligosaccharide consisting of 2,6-methylated cyclic α(1→4)-linked glucopyranose moieties, was shown to be capable of inducing stilbene biosynthesis in liquid grape cell cultures, also in the absence of pathogenic organisms. DIMEB is capable of inducing a response in the liquid cell cultures of the Vitis vinifera cultivars Pinot Noir and Merzling and furthermore in V. amurensis and a cross between V. riparia and V. berlandieri. More detailed attention was focused on different responses in cell suspensions of Pinot Noir and the cross of V. riparia and V. berlandieri after DIMEB treatment

Cultivar, juice extraction, ultra violet irradiation and storage influence the stilbene content of muscadine grapes (Vitis rotundifolia Michx.)

Stilbene concentration was analyzed in juice and tissue of muscadine grape (Vitis rotundifolia Michx.) and bunch grape (Vitis labrusca L.) from fresh fruit, after processing and after postharvest treatments. Five filter types were evaluated for percent resveratrol recovery when filtering standard and spiked juice samples in preparation for HPLC analysis. Only two (polycarbonate and Anopore) of the five filter types had more than 90 percent recovery. Polycarbonate was chosen for sample preparation since it was more durable during handling. Eight muscadine grape cultivars and three bunch grape cultivars were evaluated. Skin tissue had approximately 100 times higher stilbene concentration than did the pulp for all cultivars studied. ‘Carlos’ and ‘Magnolia’ muscadine cultivars had the greatest skin stilbene concentration of all the muscadine cultivars evaluated. Except for ‘Sweet Jenny’, bronze cultivars had greater skin stilbene concentration than black skinned cultivars. ‘Miss Blanc’ Vitis labrusca grape had greater skin stilbene concentration than all other cultivars. Stilbene concentration of fresh juice extracted from ‘Noble’ and ‘Carlos’ muscadine grapes was relatively low compared to processed juices. Juices obtained using hot press and freezing methods of juices extraction had significantly higher stilbene concentration than free run or cold pressed juice. Although ‘Carlos’ skin tissue had significantly more stilbenes than ‘Noble’ skins, there were no significant differences between free run, cold press or hot press juices obtained from the two cultivars. Although pectic enzyme treatment significantly increased juice yields, stilbene concentrations were not significantly higher than other juice extraction methods. In contrast to ‘Carlos’ muscadine grape, where high skin stilbene concentration did not result in high juice concentration, Vitis labrusca grape juices had relatively high stilbene concentration when compared to muscadine juices. UV irradiation and cold storage had a significant effect on stilbene concentration of muscadine grape tissue. For ‘Carlos’ muscadine grape, cold storage alone doubled skin stilbene concentration, but UV irradiation did not significantly change stilbene levels. In contrast, in ‘Noble’ muscadine grape, UV irradiation increased skin stilbene concentration by 50%, but cold storage alone had no effect

Resveratrol metabolite profiling in clinical nutrition research-from diet to uncovering disease risk biomarkers: epidemiological evidence

Resveratrol is a bioactive plant compound that has drawn scientific and media attention owing to its protective effects against a wide variety of illnesses, including cardiovascular diseases and cancer. In the last two decades, a plethora of preclinical studies have shown these beneficial effects, and some of them have been supported by clinical trials. However, there are few epidemiological studies assessing these relationships, showing mostly inconsistent results among them. This could be partially due to the difficulty of accurately estimating dietary resveratrol exposure. The development of Phenol-Explorer, a database containing resveratrol food-composition data, will facilitate the estimation of resveratrol intake. Moreover, the discovery and validation of a nutritional biomarker of this exposure, urinary resveratrol metabolite profile, will allow a more accurate assessment of dietary resveratrol exposure. Few epidemiological studies have assessed the potential health effects of resveratrol. Resveratrol was not associated with total mortality, cancer, or cardiovascular events, but it was associated with an improvement of serum glucose and triglyceride levels and a decrease in heart rate. Together, these findings suggest a potential cardioprotective effect of resveratrol in epidemiological studies, although the evidence is still scarce

Stability and Photoisomerization of Stilbenes Isolated from the Bark of Norway Spruce Roots

Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce (Picea abies L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent light induce trans to cis isomerisation via intramolecular cyclization. So far, the characterizations of possible new compounds derived from trans-stilbenes under UV light exposure have been mainly tentative based only on UV or MS spectra without utilizing more detailed structural spectroscopy techniques such as NMR. The objective of this work was to study the stability of biologically interesting and readily available stilbenes such as astringin and isorhapontin and their aglucones piceatannol and isorhapontigenin, which have not been studied previously. The effects of fluorescent and UV light and storage on the stability of trans stilbenes were assessed and the identification and characterisation of new compounds formed during our experiments were carried out by chromatographic (HPLC, GC) and spectroscopic techniques (UV, MS, NMR). The stilbenes undergo a trans to cis isomerisation under extended UV irradiation by intramolecular cyclisation (by the formation of a new C-C bond and the loss of two hydrogens) to phenanthrene structures. The characterised compounds are novel and not described previously