水溶液中白藜芦醇稳定性及降解产物分析

白藜芦醇是一种具有较强抗氧化和防癌、抗癌等生理活性的植物天然产物,其功能与生产是当前的研究热点;然而,白藜芦醇的光稳定性和热稳定性较差。在微生物发酵生产及存储过程中需要采取特殊的工艺,以防止其降解,使得发酵及存储工艺复杂化,增加了成本。本研究对发酵及存储过程中的各类条件,如温度、pH、培养基成分及大肠杆菌对白藜芦醇的降解情况进行了初步的研究;使用液相色谱-离子阱-飞行时间质谱,对白藜芦醇的降解产物进行了分析。本研究可作为基础资料,为降低发酵生产及存储过程中白藜芦醇的降解提供重要参考。     

Levels of 4-hydroxystilbene-oxidizing isoperoxidases related to constitutive disease resistance in in vitro-cultured grapevine

A zymographic screening of peroxidases (EC 1.11.1.7) capable of oxidizing 4-hydroxystilbene was carried out by means of the peroxidase-catalyzed oxidative coupling of 4-hydroxystilbene and 4-aminoantipyrine. This screening reveals that only a few isoperoxidases are active in oxidizing 4-hydroxystilbene to viniferin-type compounds in in vitro cultures of grapevine. Unlike total peroxidase activity measured with 4-methoxy--naphthol, the levels of total peroxidase activity measured using 4-hydroxystilbene are related to disease resistance against downy mildew in axillary bud cultures of Vitis vinifera and (Vitis vinifera x Vitis rupestris) x Vitis riparia. From this observation, and using the above zymographic assay, it was found that a 4-hydroxystilbene-oxidizing isoperoxidase was overexpressed in both leaves and stems of the hybrid in relation to the increase in disease resistance of this species. These results suggest that constitutive 4-hydroxystilbene-oxidizing isoperoxidases may participate through their role in viniferin synthesis in the constitutive resistance mechanism that grapevines show against downy mildew.Abbreviations 4-AAP 4-aminoantipyrine - HRP horseradish peroxidase - 4-HS hydroxystilbene - HSPrx 4-hydroxystilbene-oxidizing peroxidase - 4-MN 4-methoxy--naphthol     

Differential expression of a cell wall-localized peroxidase isoenzyme capable of oxidizing 4-hydroxystilbenes during the cell culture of grapevine (Vitis vinifera cv. Airen and Monastrell)

Differential expression and localization of peroxidase isoenzymes capable of oxidizing 4-hydroxystilbenes was studied during establishment of callus cultures from Vitis vinifera Airen (anthocyanin-non accumulating) and Monastrell (anthocyanin-accumulating) berries. Callus formation from mesocarp tissues was accompanied by differential expression of several peroxidase isoenzyemes located in cell walls, among which only peroxidase isoenzyme A₁ was capable of oxidizing 4-hydroxystilbene to any great extent. Likewise, grape cell cultures were capable of accumulating the grape stilbene phytoalexin, resveratrol. However, -viniferin, the most powerful phytoalexin in grapevines and previously considered as the product of peroxidase-mediated oxidative coupling of two resveratrol moieties, was only detectable in trace amounts. Since grapevine suspension cell cultures were unable to produce H₂O₂ as revealed by the luminol test, H₂O₂ production by the cultured cells appears to be one of the main factors which limits resveratrol oxidation in the cell walls of grapevine cells cultured in suspension.     

葡萄植株中白藜芦醇及葡萄素含量动态积累规律研究

对葡萄生长期间不同部位中主要活性成分白藜芦醇和葡萄素含量进行了分析,探索了活性成分代谢积累规律.以湖南省境内的主要葡萄品种红地球的主藤、侧藤、支藤、根、叶、叶柄为研究对象,从2010年4月到2011年1月考察了白藜芦醇与葡萄素含量的动态变化,采用超声波辅助甲醇提取法对实验材料进行白藜芦醇和葡萄素提取,以高效液相色谱法进行白藜芦醇和葡萄素含量测定来考察白藜芦醇和葡萄素在葡萄植株中动态变化的规律.结果表明:葡萄植株中不同部位白藜芦醇和葡萄素含量差异显著,主藤＞侧藤＞支藤＞根＞叶片≈叶柄;各部位白藜芦醇和葡萄素在生长期含量变化趋势是先升后降,尤其是葡萄素变化趋势很明显,白藜芦醇变化趋势较小,各部位芪化物含量在9～10月含量处于峰值.