牛蒡多酚的提取及清除DPPH自由基的研究

[目的]提取牛蒡多酚,并进行抗氧化性试验。[方法]采用不同预处理方法处理牛蒡,并提取牛蒡多酚物质;采用电子顺磁共振技术（EPR）,分别检测不同浓度牛蒡多酚对DPPH自由基的清除作用。[结果]Vc浸泡处理后,牛蒡多酚提取率最高;牛蒡多酚浓度与清除效用呈线性关系,其半数清除率EC50为202.04μg/ml。[结论]Vc浸泡处理后的牛蒡多酚在一定浓度范围内具明显的清除DPPH自由基作用。EPR检测自由基方法快速、灵敏。     

芥菜型油菜黄黑种皮多酚差异的紫外-可见光谱研究

以芥菜型自交系黄黑油菜种皮为材料,研究了其多酚提取液的紫外-可见吸收光谱, 测定了芥菜型油菜黄黑种皮样以没食子酸和茶儿茶素标准计的多酚含量,发现黄种皮的多酚含量约为黑种皮的90%,显著区别于甘蓝型油菜的10%,因此多酚含量高可能是芥菜型黄籽油菜性状稳定的根本内因。基于香草醛试验,推测黑种皮中含有3-OH的黄烷醇类多酚,而黄种皮中没有。基于加入位移试剂后特征吸收谱带Ⅰ与Ⅱ的位移方向与大小,推测黄酮醇类多酚A环在黄种皮中可能主要为单酚羟基,而在黑种皮中可能主要为邻二酚羟基结构。这种多酚分子的结构差异可能是形成芥菜型油菜黄黑种皮色泽差异的主要原因。     

Disease and pest resistance in grains of sorghum and millets

In this review available information on the mechanisms of resistance to insect pests and fungal pathogens in sorghum and millets is discussed. The primary source of resistance lies in the chemical and physical make up of the grain. Phenolic compounds such as ferulic acid and tannins present in some sorghums are potent inhibitors of pests and pathogens. Grain hardness is a major deterrent to infection and infestation in low tannin grains. The prolamins, the grain storage proteins of sorghum, are organized into protein bodies and provide a physical and a nutritional barrier since they are resistant to digestion by insect and fungal proteases. A plethora of proteins that belong to the ‘pathogenesis related protein’ group are distributed in various parts of the grain. Some of them are located in protein bodies. Notwithstanding, sorghum is still susceptible to insect pests and fungal pathogens. An understanding of the natural mechanisms of resistance in the grain is paramount for the development of durable resistance against pests and pathogens. The pyramiding of resistance genes and the development of transgenic lines based on this understanding are two sources of hope for the future protection of sorghum and millets.     

红碎茶发酵过程中多酚类物质含量变化的研究

用云南大叶群体种作材料，控制在一定温湿度等环境条件下，用仿制C．T．C揉切机砌碎。每隔20min取一次发酵叶烘干，后然对不同处理的茶样进行生化测定，测定出茶多酚（多酚类化合物）总量、儿茶素的总量都 着发酵时间的延长而逐渐减少，儿茶素的次级氧化物产物茶黄素（TF）、茶红素（TR）的含量是随着发酵时间延长而逐渐增加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期的于茶加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期后于茶黄素，茶褐素（TB）的含量是随着发酵时间的延长而逐渐增加，从茶化分析结合感官审评的结果，温度在22－26℃，地湿度在90％以上，发酵时间在80min左右，制出的红碎茶品质最好。     

枣果中多酚物质的体外活性研究

通过酒石酸铁法对枣果中多酚类物质的含量进行了测定,并利用化学发光分析法测定了枣果中多酚物质间苯三酚和邻苯二酚的体外抗氧化活性。结果表明:枣果中多酚类物质间苯三酚和邻苯二酚对·OH、NO2-具有较明显的抑制作用,为枣产品保健功能的开发利用提供了新的研究方向和理论基础。     

植物多酚抑菌作用的对比研究

滤纸片法测定了不同浓度的植物多酚对不同供试菌株的抑制作用。结果显示,三种植物多酚对供试菌都有一定的抑菌作用,它们对细菌的抑菌效果比对酵母、霉菌的更明显;三种植物多酚都有较宽的抑菌活性pH范围,经60℃、8O℃、100℃水浴处理15m in后仍能保持原有的抗菌效力。和其它两种植物多酚相比,茶多酚的抑菌效力更为显著,抑菌活性pH值范围更宽,热稳定性更好。     

Antiradical properties of sorghum (Sorghum bicolor L. Moench) flour extracts

Epidemiological studies support the belief that whole grains are protective against several chronic diseases. The health benefits of whole grains are attributed in part to their unique phytochemical composition. Major phytochemicals in grains include various classes of phenolic compounds, flavonoids and coumarin derivatives, etc. Phenolic compounds present in grains possess antioxidant properties that are associated with the health benefits of grains and grain products. Sorghum is one of the main staple cereal grains in hot dry tropics and ranks fifth among cereal crops in the world. Although sorghum is rich in phenolics and tannins which are proven anticancer and cardioprotective constituents, human consumption of sorghum is limited. To our knowledge, there is limited literature on the profile of antioxidant phytochemicals in the local white variety of sorghum. Hence, the objective of this study was to investigate the antioxidant property of white sorghum flour extracts in vitro and also to identify the fractions responsible for the antioxidant activity. In the present study, we analyzed the antioxidative properties of various extracts (water, 60% methanol, 60% ethanol, and 60% t-butanol) of white sorghum flour employing the 1,1-diphenyl-2-picrylhydrazyl (DPPH) model system. Phenolics, antiradical and antioxidant activities were also examined in chromatographic sub-fractions of the soxhlet methanolic extract. Our results indicated that the various extracts exhibited significant antioxidant activity that did not correlate with the phenolic content. Further, two sub-fractions eluted with methanol and acetone/methanol were found to possess strong antioxidant activity in two assay systems. Our results suggest that a diet rich in sorghum may be useful in combating diseases in which free radical production plays a key role.     

The fate of condensed tannins during litter consumption by soil animals

Condensed tannins (CT) can strongly affect litter decomposition, but their fate during the decomposition process, in particular as influenced by detritivore consumption, is not well understood. We tested the hypothesis that litter CT are reduced by the gut passage of two functionally distinct detritivores of Mediterranean forests, the millipede Glomeris marginata, and the land snail Pomatias elegans, as a fixed proportion of initial litter CT, but more so in Pomatias since snails are known to have a more efficient enzymatic capacity. Contrary to our hypothesis, both detritivore species reduced litter CT to near zero in their faecal pellets irrespective of the wide range in initial leaf litter CT concentrations of 9-188 mg g⁻¹ d m among three Mediterranean tree species (Pistacia terebinthus, Quercus ilex, Alnus glutinosa) and different decomposition stages of their litter. The almost complete disappearance of CT even from some litter types highly concentrated in CT, due to either degradation by gut microorganism or complexation of CT into insoluble high molecular weight structures, suggests a high “de-tanning” efficiency across functionally distinct detritivore species. The transformation of CT-rich litter into virtually CT-free faecal pellets by detritivores might be highly relevant for the subsequent decomposition process in ecosystems with a high macrofauna abundance and CT-rich plant species such as Mediterranean forests.     

核桃青皮多酚的抗氧化性研究

通过体外抗氧化体系对核桃青皮多酚的抗氧化能力进行研究。结果表明,核桃青皮多酚在各体系中均有一定的抗氧化性能,并且其抗氧化能力随着浓度的增加而增强;在所选浓度下,核桃青皮多酚对DPPH自由基和过氧化氢的清除能力、对三价铁离子的还原能力均明显强于VC。当其质量浓度高于10 mg/L时,核桃青皮多酚对羟基自由基的清除作用强于VC对超氧阴离子自由基的清除作用;当其质量浓度低于22.3 mg/L时,核桃青皮多酚对超氧阴离子自由基的清除力强于VC对超氧阴离子自由基的清除作用。     

微波法提取杨桃渣中多酚的工艺研究

[目的]研究微波法提取杨桃渣中多酚的工艺条件。[方法]利用微波提取法,通过单因素研究了5个因素对杨桃多酚提取率的影响,并通过正交试验筛选提取杨桃渣多酚的最佳工艺条件。[结果]单因素试验表明,物料粒径30目,微波功率560W、60％乙醇浓度、料液比1：50、提取时间60S、提取2次可得到从杨桃渣中提取多酚的最佳效果。正交试验表明,4因素对微波提取杨桃渣多酚的影响顺序为溶剂浓度〉料液比〉提取时间〉功率;微波法从杨桃渣中提取多酚的最佳工艺条件为：乙醇浓度50％、物料颗粒30目、液料比1：70、微波功率700W、提取时间60S,在此条件下从杨桃渣中提取的多酚浓度可达18．725mg／g。[结论]微波辅助萃取具有提取率更高、所需时间短的特点．应用前景广阔