乙醇法提取枇杷叶总黄酮的研究

对乙醇法提取枇杷叶黄酮的工艺进行研究,采用单因素试验法对影响枇杷叶中黄酮类物质提取率的主要因素进行了考察,利用正交试验优化了提取黄酮类物质的最佳工艺条件。确定了枇杷叶总黄酮的最佳提取工艺为∶料液比1∶50,提取温度80℃,提取时间3 h,乙醇浓度50%。在最佳提取工艺条件下测得解放钟枇杷叶中总黄酮含量为0.3805%,回收率98.37%。     

金银木叶总黄酮提取工艺的响应面设计优化

[目的]优化并确定金银木叶中总黄酮的最佳提取工艺。[方法]在单因素试验的基础上,选用乙醇体积分数、提取温度、液料比作为研究对象,通过3因素、3水平的Box-Behnken响应面法确定金银木叶总黄酮提取的最佳工艺。[结果]试验表明,金银木叶总黄酮的最佳提取工艺为,乙醇体积分数68%,提取温度67℃,液料比27∶1 ml/g,在此条件下,黄酮提取率可达到12.88%。[结论]研究可为金银木的充分利用以及新的抗氧化药物的开发提供参考依据。     

增强UV-B条件下类黄酮与苦荞逆境伤害和抗氧化酶的关系

经增强UV-B处理后,苦荞水培苗表现出胁迫效应,其相对电导率和MDA含量提高,而叶绿素含量和光合速率下降。增强UV-B处理诱导叶片类黄酮含量提高,但高幅照度和长时间UV-B处理则使后期类黄酮含量下降。叶片类黄酮含量与UV-B逆境伤害程度和抗氧化酶活性相关,外施类黄酮物质芦丁可以降低MDA含量和维持SOD活性在较高水平。     

二次回归正交设计优化紫茎泽兰中黄酮的提取工艺

[目的]研究从紫茎泽兰中提取黄酮的最佳工艺条件。[方法]以黄酮的得率为目标,使用单因素试验方法考察乙醇浓度、提取温度、固液比以及提取时间对黄酮得率的影响,使用回归正交组合设计优化提取工艺。[结果]最优的黄酮工艺条件为：固液比为1：30,提取时间为2．5h,乙醇浓度为53％,提取温度为70℃。[结论]使用回归正交组合设计能合理地优化紫茎泽兰中黄酮的提取工艺,为紫茎泽兰的综合利用提供参考。     

Knotwood and bark extracts: strong antioxidants from waste materials

The antioxidant properties of hydrophilic extracts of knotwood of several industrially important tree species were evaluated by lipid-peroxidation inhibition and peroxyl-trapping capacity tests. The results were compared with the antioxidant properties of hydrophilic extracts of bark, and pure lignans and flavonoids isolated from knotwood extracts. The knot extracts from several tree species were stronger antioxidants than the bark extracts, which can, however, also be classified as strong antioxidants. In addition, the antioxidant properties of most of the knotwood extracts are stronger than the pure compounds. It is concluded that knotwood is a rich source of natural antioxidants.     

荔枝冷害过程中果皮色泽、花色素苷和类黄酮含量的变化

 研究了‘糯米糍’荔枝果实在3 ℃和0 ℃条件下果皮的色泽和花色素苷及类黄酮含量的变化。结果表明, 果实在0 ℃下14 d 时褐变指数迅速增大, 21 d 时已遭受不可逆的冷害。在冷藏过程中, 果皮的色泽指标a、L、C 值及花色素苷、类黄酮、总酚含量均随贮藏时间的延长而下降, 0 ℃下比3 ℃下降快。0 ℃下14～21 d , a、L、C 值分别下降了27.95 %、33.58 %和58.47 % , 而21 d 时果皮花色素苷、类黄酮和总酚含量依次为采收时的18.08 %、35.99 %和41.64 %。说明冷害加速了荔枝果皮花色素苷的降解及类黄酮和总酚的变化, 促进了褐变进程的发生。果皮a、L、C 值与褐变指数、花色素苷含量呈显著相关性( P < 0.05) ,采用自动测色色度计可真实地反映果皮花色素苷含量和褐变程度。     

Protective and defensive roles of non-glandular trichomes against multiple stresses:structure-function coordination

As superficial structures,non-glandular trichomes,protect plant organs against multiple biotic and abiotic stresses.The protective and defensive roles of these epidermal appendages are crucial to developing organs and can be attributed to the excellent combination of suitable structural traits and chemical reinforcement in the form of phenolic compounds,primarily fl avonoids.Both the formation of trichomes and the accumulation of phenolics are interrelated at the molecular level.During the early stages of development,non-glandular trichomes show strong morphological similarities to glandular ones such as the balloon-like apical cells with numerous phenolics.At later developmental stages,and during secondary wall thickening,phenolics are transferred to the cell walls of the trichomes.Due to the diff use deposition of phenolics in the cell walls,trichomes provide protection against UV-B radiation by behaving as optical fi lters,screening out wavelengths that could damage sensitive tissues.Protection from strong visible radiation is also aff orded by increased surface light refl ectance.Moreover,the mixtures of trichome phenolics represent a superfi-cial chemical barrier that provides protection against biotic stress factors such as herbivores and pathogens.Although the cells of some trichomes die at maturity,they can modulate their quantitative and qualitative characteristics during development,depending on the prevailing conditions of the external biotic or abiotic environment.In fact,the structure and chemical constituents of trichomes may change due to the particular light regime,herbivore damage,wounding,water stress,salinity and the presence of heavy metals.Hence,trichomes represent dynamic protective structures that may greatly aff ect the outcome of many plant–environment interactions.     

Compositional analysis and in vivo anti-diabetic activity of wild Algerian Marrubium vulgare L. infusion

Marrubium vulgare (Lamiaceae) is a plant traditionally used for the treatment of diabetes in Algeria. Compositional analysis of the aqueous infusion revealed the presence of fifteen metabolites, all belonging to the class of polyphenols. Particularly, seven flavonoids have been detected, together with 5-caffeoylquinic (chlorogenic) acid in small amounts; the extract is dominated by the presence of a series of complex molecules, characterized as verbascoside (acteoside) derivatives. Concerning the anti-diabetic effectiveness a series of in vivo experiments were carried out on albinos Wistar rats. Diabetes was induced in the animals by intra-peritoneal injection of alloxane; they were treated twice a day with aqueous extract from aerial part infusion (100, 200 and 300 mg/kg body weight) and glibenclamide (5mg/kg body weight) for 15 days. Oral administration of 200 and 300 mg/kg body weight of aqueous extract the Marrubium vulgare induced an significant effect antidiabetic and antihyperlipidemic (dose-dependent effect). A decrease in blood glucose by 50% for the dose 100 mg/kg and more than 60% for doses 200 and 300 mg/kg, as well as a significant lowering of total lipids, triglycerides, and total cholesterol levels in treated animals, compared with diabetic controls group (p<0.001), have been observed. Glibenclamide was used as reference and showed similar effects.     

Evaluation of phenolics and antioxidant activity of black sorghum hybrids

Black sorghums possess very high levels of the rare 3-deoxyanthocyanidins which can be used as natural food colorants with health benefits. However, these sorghum genotypes have undesirable agronomic properties (i.e. high height, low yield, increased weathering). Black sorghum hybrids with improved agronomic properties were developed and their phenolic profiles and antioxidant activity were compared with black sorghum lines. Black sorghum hybrids were significantly lighter in colour than the lines (P < 0.001). All hybrids had a pigmented testa which was indicated by the presence of condensed tannins, which significantly increased total phenol levels and antioxidant activity. The 3-deoxyanthocyanidin, flavan-4-ol, and flavone levels were significantly lower in the hybrids (P < 0.001) and were strongly correlated to pericarp colour (P < 0.001). Flavanone levels were not significantly different among the lines and hybrids (P > 0.05) and pericarp colour did not affect their levels (P > 0.05). Even though the 3-deoxyanthocyanidin levels were lower in black sorghum hybrids than in the lines, the presence of condensed tannins in the hybrids significantly increased their antioxidant activity. Since 3-deoxyanthocanidin levels were dependent on pericarp colour, hybrids with increased blackness intensity should be developed to increase the stable 3-deoxyanthocyanidins.     

油杉花粉萌发与花粉管细胞骨架系统的研究

应用免疫荧光标记法结合激光扫描共聚焦显微镜术对油杉花粉管中的微管、微丝骨架进行观察.结果表明:伸长的花粉管大致可分为3个区,即位于顶端的管细胞区、体细胞区和其后的退化区;花粉管中微管与微丝的分布样式不同;微管骨架主要分布于管细胞区和体细胞区,而退化区的微管较稀疏;管细胞区内微管呈网状结构,微管一直延伸至花粉管极顶端;体细胞具独立的微管系统.花粉管内微丝骨架呈轴向排列于整个花粉管,自花粉粒内一直延伸至花粉管顶端,粗微丝束几乎平行于花粉管的长轴.本研究结果为进一步研究微管与微丝骨架系统在油杉花粉管顶端极性生长中的作用提供依据.