Stilbenes in the different organs of Vitis vinifera cv. Merlot grafted on Teleki Kober 5BB rootstock

摘要

Aim: To determine which of the grapevine organ is the richest in stilbene, like the t-piceid, t-resveratrol and ε-viniferin and would it be useful as by-product of viticulture for processing stilbene concentrate.Methods and results: Nine organs, such as cane, buds, shoot tips, inflorescences, clusters at veraison, matured berry skins, seeds and cluster stems, of Merlot grafted on Teleki Kober 5BB rootstock were collected during a year and its ethanolic extractions were analyzed via HPLC-FLD. Stilbene content of the different organs occurred in a wide range, the lowest was 3.15 mg/kg dry weight (dw) measured in the seeds and the highest 2265 mg/kg dw in the buds.Conclusion: The present research demonstrated that different grapevine organs contain different amount of stilbene in the vineyard. The winter-buds, the roots and the matured cane internodes of Merlot are significantly richer in t-resveratrol and t-ε-viniferin than the green vegetative and generative parts we examined in one growing year. Significance and impact of the study: According to our knowledge there was no stilbenes measuring in several plant organs of a vine cultivar in field study, in vineyard. Our research pointed out the pruned cane could be primary source of stilbene of the health-industry. Beside that grape root is a by-product of grapevine nursery is also rich in stilbene. Introduction Stilbenes are natural phenolic compounds occurring in a number of plant families including Vitaceae. Resveratrol is a low molecular weight stilbene molecule, its 3-O-glucoside is piceid and one of the resveratrol oligomers is ε-viniferin, a dehydrodimer. The putative medical benefits of stilbenes were intensively studied during the last decade. Resveratrol is an antioxidant agent that is thought to fend off cardiovascular diseases and cancer; influence Alzheimer’s disease and ageing; and prevent bone loss and diabetes (Tosun and Inkaya, 2009). The biological activities of piceid have not been thoroughly studied, but it seems it may also have beneficial effects on health (Chong et al., 2009). ε-Viniferin has promising actions in vitro, like decreasing glucose absorption (Guschlbauer et al., 2013) and inhibiting vascular muscle cell proliferation (Zghonda et al., 2011) and amyloid-beta peptide aggregation (Rivière et al., 2010). Resveratrol and its derivatives are naturally produced by plants as self-defence agents either in response to biotic or abiotic stress or constitutively without elicitors (Jeandet et al., 2010), and thus can be considered as phytoalexins and phytoanticipins. Stilbenes were detected or quantified in different vine organs, such as berries, seeds, berry skin, cluster stems, leaves, canes, roots (Waffo-Teguo et al., 2008), flowers (Keller et al., 2003; Timperio et al., 2012) and buds (Wang et al., 2010; Qsaib et al., 2014). To our knowledge, no measurement of stilbene content in several plant organs of a vine cultivar in a field study has been reported, and only limited data are available on grape root resveratrol and ε-viniferin content. Materials and methods 1. Plant material and field conditions Vitis vinifera cv. Merlot red wine grape cultivar was established on Teleki Kober 5BB (TK5BB) rootstock in 2004 in Szekszárd, Hungary (46°19’30’’N/18°41’09’’E, 130 m altitude). The effective temperature was 3538°C and rainfall was 798 mm in 2013. 2. Sample collection Visually healthy plant organs were collected from 10 randomly chosen vines from the vineyard. Samples were pooled replicates and we made three technical repeats. The shoot tips and inflorescences were collected at full bloom in 2013. Clusters were collected at veraison and at harvest in 2013. The internodes of the cane, the bud and the root samples were collected in the dormant season in February 2014 (Figure 1). Figure 1. investigated organs of the grape plant. Winter-buds (1), cane internodes (2), surface roots of the rootstock (3), shoot tip with a young leaf and a tendril at the beginning of the leaf expansion (4), inflorescence at full bloom (5), cluster at veraison (6), and cluster stem (7a), berry skins (7b) and seeds (7c) of a ripe grape cluster. Save View full size Expand inline Collapse inline 3. Sample processing Sample preparation and extraction was performed with minor modifications according to the method of Rayne et al. (2008) within a day after collection. The ripe cluster was destemmed, and the skin and seeds were separated from the berries. The samples of plant material were treated with liquid nitrogen, then ground into powder (Moulinex AR100) and kept at -70°C in the dark until further processing. 1 g of fresh sample powder (particle size 99% purity), t-piceid (>95% purity) and ε-viniferin (>95% purity) standards were obtained from VWR International. 5. Chromatographic methods HPLC-FLD analyses were conducted on Perkin Elmer Flexar chromatograph system and Chromera-Flexar FL data collection software. The analytical column Zorbax Eclipse XDB-C8 4.6×150 mm wa