Recent Achievements in the Bio-control of Orobanche Infesting Important Crops in the Mediterranean Basin

Orobanche spp. （broomrapes） are holoparasitic plants distributed predominantly in the Northern Hemisphere parasitizing the roots of a range of plant species mainly in wild ecosystems. Orobanche species cause severe yield reduction of many important crops. There are only very few herbicides which are able to selectively control broomrapes and different approaches have been put forward to develop natural product based pesticides to control Orobanche. Several phytopathogenic fungi were evaluated for their use as potential mycoherbicide and for ability to produce toxic metabolites which could be applied as herbicides. Using the alternative approach ＂suicidal germination＂, interesting results were obtained by testing two microbial metabolites （fusicoccins and ophiobolin A） especially with Orobanche species whose germination is not induced by the synthetic strigolactone GR24. From pea root exudates, peagol and peagoldione, close related to strigolactones, and three polyphenols, named peapolyphenols A-C, together with already well known polyphenol and a chalcone, were isolated. They showed a selective stimulation of Orobanche seed germination with the last two and peapolyphenol A showing a specific stimulatory activity on O. foetida. This review describes the most recent results achieved on Orobanche bio-control, mainly focusing on those regarding O. ramosa, O. crenata and O. foetida.     

超高压技术提取的花生壳多酚的抗氧化活性

采用超高压提取技术对花生壳多酚进行了提取,测得的提取率为7.1 mg/g.以维生素C和特丁基对苯二酚(TBHQ)2种常用抗氧化剂为对照,测定了花生壳多酚的抗氧化能力.结果表明:在质量浓度为1 mg/mL时,其对羟基自由基的清除率达到69.1%,还原力为0.364,抗脂质体活性为82%,对DPPH自由基的清除率为68.5%.而相同浓度的维生素C与TBHQ对羟基自由基的清除率分别为57.3%,37.9%,还原力分别为0.959,0.396,抗脂质体活性分别为19.4%,19.8%,对DPPH自由基的清除率分别为96.1%,94.4%.可以认为超高压提取的花生壳多酚有很好的清除自由基能力和抗氧化活性.     

电氧化法快速测定茶还原性多酚类的含量

还原性多酚类与茶叶的抗氧化有关。还原性多酚类被电氧化后,在325 nm处产生新的光吸收峰,茶汤电氧化前后在325 nm处光吸收的差值与还原性多酚类含量成线性关系,利用此关系建立了快速测定茶还原性多酚类含量的新方法。应用本方法测定结果显示,绿茶中还原性多酚类含量较高,而普洱茶中含量极低。     

HPLC测定两种中国蜂胶醇提物化学组成

建立了同时测定蜂胶醇提物(EEP)中23种多酚类化合物的高效液相色谱(HPLC)分析方法,并用该法测定了分别采自山东济宁和云南西双版纳的EEP。采用ZORBAX Eclipse XDB C18色谱柱(4.6 mm×150 mm,5μm),流动相为甲醇-0.1%甲酸水溶液,梯度洗脱,流速1.0 mL/min,检测波长256和280 nm,进样量20μL,柱温35℃。结果表明,所用的分离条件可以使混合对照品及EEP均实现良好分离。通过对比保留时间和紫外吸收光谱,从山东蜂胶中鉴定出20种化合物,云南蜂胶中鉴定出14种化合物。两地EEP的HPLC图谱相似度分别为0.417(256 nm)和0.499(280 nm),两者化学成分差异巨大。山东济宁和云南西双版纳分别地处温带和热带地区,不同的气候及植被可能是这种差异的主要原因。     

一种适合于富含多糖和酚类物质的香蕉果实RNA提取方法

酚类化合物和多糖是影响香蕉组织RNA提取的几个主要干扰因素。研究通过在裂解液中加入聚乙烯吡咯烷酮去除多酚类化合物和利用水饱和乙醚去除多糖,改进了香蕉果实RNA的提取方法。该方法具有快速、简单等特点。     

高温操作及贮存过程中葡萄多酚的稳定性

对葡萄籽多酚提取物在高温操作及贮存过程中的稳定性进行了研究。结果表明,25℃时,葡萄多酚在80%的乙醇溶液中可存放5d,在水溶液中可存放3d。高温处理(90℃时超过12h,50℃时超过24h)使葡萄籽提取物的颜色变深,原花青素含量降低,但对总酚含量及DPPH自由基的清除能力影响不大。水不溶性葡萄多酚与水溶性酚类物质在相同的总酚含量下,对DPPH的清除能力无明显差异。     

云南烤烟石油醚提取物和多酚类与气候要素的关系

为了解云南烤烟香气物质含量，烟区间或年度间的变异及其生态生理学原因，利用地理播种研究法，在选定的云南7个烟区连续3年对同品种云南烤烟石油醚提取物含量和多酚类香气物质与气候要素关系的区域性大田试验进行了比较研究，结果表明：云南烤烟胎溶性香气量明显低于美国北卡州烟叶，但多酚类物质较接近，影响云南烤烟脂溶性香气物质含量的主要气候要素是烤烟大田期的总降水量和大田期的旬均光照强度，前者为负效应，后者为正效应，并以降水量的影响最为强烈；大田期旬均光照度是影响云南烤烟多酚类物质积累的主要气候要素。     

苦丁茶化学成份研究——多酚类与咖啡碱和Vc含量

分析了苦丁茶多酚类总量、儿茶素组成、咖啡碱和维生素C含量.结果表明,苦丁茶含有少量的表儿茶素(EC)、表没食子儿茶素没食子酸酯(EGCG)和表儿茶素没食子酸酯(ECG),不含表没食子儿茶素(EGC)和( )-儿茶素[( )-C],咖啡碱含量为0.0228～0.0436％,约为茶叶的1/100;维生素C含量为31.21～45.60mg/100g.在被测代谢物中,苦丁茶与茶叶具有不同的代谢类型.     

基于响应面法优化酶法提取花生壳多酚类化合物的工艺

以花生壳为原料,在单因素试验的基础上,以pH值、酶量、酶解温度和酶解时间为试验因素,以多酚提取率为响应值,利用Box-Behnken试验设计进行四因素三水平响应面分析,建立相应回归方程,对酶辅助提取花生壳多酚类化合物的工艺进行优化.结果表明,花生壳多酚最佳的提取工艺为:pH 5.2,酶量8.8 mg/g,酶解温度51℃,酶解时间2.4 h,在此工艺条件下多酚提取率为6.887 mg/g,与预测值6.91 mg/g基本相符.     

Changes of Polyphenols in Tobacco Leaves During the Flue-Curing Process and Correlation Analysis on Some Chemical Components

The changes of polyphenols in tobacco leaves during the flue-curing process and correlation analysis on some chemical components were studied. Leaf samples were taken from different tobacco-producing regions in Henan Province, China. The results indicated that the content of total phenols increased during the first 24 h of curing, and then decreased. It reached the lowest value at 72 h of curing and increased rapidly after that. The content of chlorogenic acid also increased during 0-24 h of curing. But the lowest point occurred at 60 or 72 h of curing and then it increased till the end of the curing process. The content of mtin generally increased with curing, and showed little fluctuations. The changes of PPO and POD activity were the opposite. Rutin was found to have a highly significant positive correlation with total sugar （r=0.822^＊＊）, but a highly significant negative correlation with starch, nicotine, and protein.