固相萃取净化-离子色谱测定不同生长期新鲜烟叶中的7种无机阴离子

目的 为了研究不同生长期新鲜烟叶中无机阴离子的含量和变换规律,建立了一种固相萃取净化/离子色谱方法测定新鲜烟叶中的7种无机阴离子（F-,Cl-,Br-,NO2-,NO3-,SO42-,PO43-）。方法 样品经0.1 mol/L NaOH水溶液超声提取,萃取液经RP1.0cc固相萃取柱净化后,使用AS11-HC（4 mm×250 mm）色谱柱进行分离,以KOH为流动相,梯度洗脱。 结果 7种无机阴离子在0.10-5.0 μg/mL范围内具有较好的线性（r>0.996）,检出限在0.01-0.04 μg/mL之间,定量限在0.04-0.14 μg/mL之间,加标回收率为96.3%～102.1%,相对标准偏差（RSD%）在2.7%~4.8%之间。结论 方法前处理操作简单,7种无机阴离子分离好,检测灵敏准确,可用于不同生长时期新鲜烟叶样品中多种无机阴离子含量的检测分析。     

青花椒叶片水浸液的成份鉴定及其化感作用的生物测定

通过研究青花椒叶片水浸液提取物的化感成分以及对小麦种子生长的化感作用:GCMS结果表明,叶片水浸液提取物中的主要有机化学物质是:5a-雄甾烷-11-酮,(+)-细辛素,二氢-2-乙酰基苯并呋喃,正二十四烷,正二十七烷,正二十八烷,1,8-萜二烯,a-佛手柑油烯,(R)-3,7-二甲基-1,6-辛二烯-3-醇,3,7,11-三甲基-2,6,10-十二烷三烯-1-烷,正十六烷和十二烷酸等,其中包含很多被报道过的化感物质。生物测定结果表明:与对照组相比,青花椒叶片水浸液萃取酸性乙酸乙酯部分对小麦幼苗和胚根的生长以及叶绿素的含量表现出极显著的抑制作用,中性组分对小麦的幼苗和胚根的生长以及叶绿素的含量表现出显著差异,而碱性组分与对照相比,幼苗与胚根的长度差异不显著。酸性组分在5 mL时对幼苗的伸长生长和根长以及叶绿素含量的抑制作用最为强烈,且随组分浓度的增加而增加,表明青花椒叶片水浸液中确实存在化感物质。     

茶鲜叶中有机磷农药残留分析

为监测茶鲜叶中有机磷农药残留污染状况,应用超声波提取、分散固相萃取净化、气相色谱检测,建立了一种简单、快速测定茶鲜叶中7种有机磷农药(敌敌畏、乐果、毒死蜱、甲基对硫磷、马拉硫磷、杀螟硫磷和三唑磷)残留的分析方法。样品采用φ(乙酸)=1%的乙腈溶液超声提取,乙二胺-N-丙基硅烷、十八烷基硅烷键合硅胶和石墨化炭黑混合吸附剂分散萃取净化,DB-1701毛细管柱程序升温分离,火焰光度检测器测定,基质外标法定量。结果表明,在0.01～4.00mg·L-1范围内,7种有机磷农药的峰面积与其浓度呈良好的线性关系,相关系数均大于0.998,方法的检出限为0.0034～0.0136mg·kg-1,定量限为0.012～0.046mg·kg-1,加标回收率为77.7%～98.2%,相对标准偏差(n=5)为2.4%～8.7%。该方法操作简单、结果可靠、溶剂用量少,对检测条件要求低,适用于茶鲜叶中7种有机磷农药残留的检测。     

不同香型凤凰单丛鲜叶与成茶香气成分的比较分析

茶叶的香气特征是评价茶叶品质的重要指标之一。通过比较八仙、鸭屎香、乌叶三种香型单丛茶的鲜叶与成茶的香气成分,发现鲜叶与成茶的差异明显,不同香型的成茶之间香气特征差异明显大于鲜叶之间的差异。鲜叶主要含有叶醇、芳樟醇等青香、木香成分,醇类所占比例大,八仙的芝兰香特征与鲜叶含有较多其他香型鲜叶不具备的花香成分有一定关系;成茶含有较多的体现花果香味的橙花叔醇等萜烯类物质和茶吡咯等烘烤香味成分,各香型的共有特征成分橙花叔醇与芳樟醇的含量比例关系在成茶中体现,鲜叶中没体现,鸭屎香的杏仁香特征成分也在成茶中出现。研究还表明季节、海拔影响香气成分,但不改变整体香型。研究结果为进一步研究不同香型的香型形成影响因素,特别是加工过程的影响奠定基础。     

Antioxidant and toxicological evaluation of a Tamarindus indica L. leaf fluid extract

In the scientific community, there is a growing interest in Tamarindus indica L. leaves, both as a valuable nutrient and as a functional food. This paper focuses on exploring its safety and antioxidant properties. A tamarind leaf fluid extract (TFE) wholly characterised was evaluated for its anti-DPPH activity (IC₅₀ = 44.36 μg/mL) and its reducing power activity (IC₅₀ = 60.87 μg/mL). TFE also exhibited a high ferrous ion-chelating capacity, with an estimated binding constant of 1.085 mol L^? 1 while its influence over nitric oxide production in human leucocytes was irregular. At low concentrations, TFE stimulated NO output, but it significantly inhibited it when there was an increase in concentration. TFE was also classified as a non-toxic substance in two toxicity tests: the acute oral toxicity test and the oral mucous irritability test. Further toxicological assays are needed, although results so far suggest that TFE might become a functional dietary supplement.     

Exploring the Antibacterial and Antibiofilm Efficacy of Silver Nanoparticles Biosynthesized Using Punica granatum Leaves

The current research work illustrates an economical and rapid approach towards the biogenic synthesis of silver nanoparticles using aqueous Punica granatum leaves extract (PGL-AgNPs). The optimization of major parameters involved in the biosynthesis process was done using Box-Behnken Design (BBD). The effects of different independent variables (parameters), namely concentration of AgNO₃, temperature and ratio of extract to AgNO_3, on response viz. particle size and polydispersity index were analyzed. As a result of experiment designing, 17 reactions were generated, which were further validated experimentally. The statistical and mathematical approaches were employed on these reactions in order to interpret the relationship between the factors and responses. The biosynthesized nanoparticles were initially characterized by UV-vis spectrophotometry followed by physicochemical analysis for determination of particle size, polydispersity index and zeta potential via dynamic light scattering (DLS), SEM and EDX studies. Moreover, the determination of the functional group present in the leaves extract and PGL-AgNPs was done by FTIR. Antibacterial and antibiofilm efficacies of PGL-AgNPs against Gram-positive and Gram-negative bacteria were further determined. The physicochemical studies suggested that PGL-AgNPs were round in shape and of ~37.5 nm in size with uniform distribution. Our studies suggested that PGL-AgNPs exhibit potent antibacterial and antibiofilm properties.     

多元方差分析在蚕桑方面的应用

本文应用多元方差分析对不同的桑品种、蚕品种的养蚕成绩（全茧量、茧层量）及制种成绩（造卵数、产卵数）进行分析,得到多倍体桑的制种成绩极显著地高于二倍体桑;三倍体桑饲养的苏５蚕品种的养蚕成绩为最佳的结论,为养蚕、制种生产提供了一定的理论依据     

乌药叶中总黄酮提取工艺的研究

以总黄酮为考察指标,采用紫外分光光度法测定乌药叶总黄酮含量,研究乌药叶总黄酮的乙醇溶液提取工艺.通过单因素实验和正交实验,考察乙醇浓度、提取时间、固液比、提取温度、提取次数等因素对黄酮提取率的影响.结果表明,乙醇提取乌药叶总黄酮的较佳工艺条件为60%(v/v)的乙醇溶液,固液比1:60,70℃回流提取2次,每次1.5 h.在此条件下,乌药叶总黄酮提取率达3.31%.     

贵州民族药杨梅叶抗菌作用的实验研究

报道了采用管碟法对矮杨梅４ 种类型植物叶的水煎剂体外抗菌实验的研究,其结果表明对Ｇ＋ 金黄色葡萄球菌有抑菌作用,对Ｇ－ 大肠肝菌,Ｇ－ 霍乱弧菌,Ｇ－ 福氏痢疾杆菌,Ｇ－ 伤寒杆菌无抑菌作用。不同类型矮杨梅叶对细菌具选择性抑制作用,不同类型矮杨梅叶对同一细菌抑菌能力不同。     

凤凰竹叶黄酮类物质提取条件的优化

天然植物黄酮类物质具有消炎、消肿、降压、降血脂,以及清除氧自由基等多种功能,其提取物质已用于食品、药品、化妆品等产品中。