胡柚皮中黄酮类化合物提取及抗氧化性研究

通过利用二次旋转组合设计的方法探讨常山胡柚应中黄酮类化合物的最佳提取工艺参数,同时利用化学发光法测定这些黄酮类化合物的抗氧化性。结果表明:提取时间、料:液比、提取温度和乙醇浓度对提取效果都有显著影响,影响最大的因素是提取时间,随着提取时间的增加,提取效果的总的变化呈上升趋势。胡柚皮中黄酮类化合物最佳提取条件为乙醇浓度90%,料:液比1:5,提取时间115min,提取温度20℃,最大提取量为1.98g/L;推荐的工业提取条件以乙醇浓度80% ,料:液比为1:8,提取温度50℃,提取时间100min为宜。另外,实验证明胡柚皮中黄酮类化合物作为自由基清除剂存在构-效关系,是一种良好的自由基清除剂。     

正交试验优化银杏胚愈伤组织继代培养及黄酮积累

采用正交试验研究了基本培养基、NAA、6-BA、植酸(PA)4因素各3水平对银杏胚愈伤组织继代培养及黄酮积累的影响,并测定了愈伤组织生长曲线.结果表明:银杏胚愈伤组织继代培养的最佳组合是N6+NAA 3.0 mg/L+6-BA 2.0 mg/L+0.1%PA,各因子影响程度为基本培养基＞NAA＞6-BA＞PA;愈伤组织黄酮积累量最佳组合是B5+NAA 0.1 mg/L+6-BA 0.5mg/L+0.05%PA,各因子影响程度为NAA＞PA＞6-BA＞基本培养基.愈伤组织生长曲线基本呈"S"型,黄酮积累的适宜培养周期为40～50 d.     

NaCl胁迫对藜麦幼苗生长和生理指标的影响

为揭示藜麦耐盐生理机制,本研究分别采用0、50、100、150、200、250、300 mmol/L NaCl处理藜麦,于处理6、12、24、48、72、96 h后测定藜麦株高、生物量、叶绿素及类黄酮的含量。结果表明:低浓度NaCl胁迫及短时间NaCl处理(50~150 mmol/L NaCl、6~48 h)促进藜麦的生长,高浓度NaCl胁迫及长时间NaCl处理(200~300 mmol/L NaCl、72~96 h)则抑制其生长;藜麦叶片叶绿素和类黄酮含量随NaCl浓度升高呈先升后降趋势,均在100 mmol/L NaCl处理下有最大值,且随处理时间的增加呈先降后升趋势,表明适宜的NaCl浓度和处理时间会促进叶绿素和类黄酮在藜麦体内的积累,增强其抗氧化能力。     

Cross reactivity between ascorbate peroxidase and phenol (guaiacol) peroxidase

Adverse conditions often induce an increase in active oxygen species (AOS) such as hydrogen peroxide (H₂O₂). H₂O₂ is converted to water, and thus becomes detoxified by enzymes such as ascorbate peroxidase (APX; EC 1.11.1.11). APX activity is estimated by the disappearance rate of ascorbic acid, which becomes oxidized. However, ascorbate is also a substrate of guaiacol peroxidase (POX; EC 1.11.1.7). POX oxidizes phenols (including flavonoids), whereby ascorbate accepts an electron from phenoxyl or flavonoid radicals. Ascorbate becomes thereby converted to the monodehydroascorbate radical, which subsequently can become converted to dehydroascorbate. POX isozymes therefore convert hydrogen peroxide to water and oxidize ascorbate, just as APX does. POX activity is usually estimated by monitoring the formation of tetraguaiacol from guaiacol. This reaction is not specific, as some APX isozymes show rather high activity when using guaiacol or similar phenols as a substrate. It is concluded that APX activity can easily be confounded with POX activity, and vice versa. Proper methods should be used to separate the two enzyme activities.