ICP-AES同时测定辣木叶中的6种微量元素

采用湿法、泡制法、水煮法处理样品,以ICP-AES测定辣木叶中的Ca、K、Mg、Fe、Zn、Cu6种微量元素。方法简单、快速、灵敏度高、准确性好,可同时测定多种元素。6种元素的加标回收率为98%—104%,相对标准偏差均小于3.5%。     

香樟受酸胁迫影响的高光谱诊断模型

高光谱作为快速、无损诊断技术,在植物胁迫监测中发挥了重要作用。但是因为硫和氮的施肥作用,植物对酸雨的响应表现出比其他胁迫更加复杂的模式。基于高光谱技术对香樟受四个酸雨梯度(pH 5.6,pH 4.5,pH 3.0,pH 2.0)影响的叶片光谱进行了419天的监测,以探讨不同酸雨梯度对香樟影响的时间拐点。首先对16期原始光谱数据进行预处理,剔除异常值;然后基于光谱差值(对照组pH 5.6与其他酸雨梯度处理下的叶片光谱差)随着喷酸时间的变化,寻找典型波段;在此基础上构建了香樟在酸雨处理下的光谱响应模型。主要结论如下：反映香樟受酸雨影响的典型波段主要集中在470~520和565~700 nm,在此基础上构建了蓝边差值指数和黄边差值指数。低(pH 4.5)、中(pH 3.0)浓度的酸雨对香樟生长均呈现出先促进后抑制的作用,时间拐点分别发生在喷酸的第100天和50天左右;高浓度酸雨(pH 2.0)从喷酸初期就表现出抑制香樟生长,且随着喷酸时间的增加抑制作用增强。研究表明,长时间序列的高光谱信息可以指示不同强度的酸雨对植物的促进和胁迫作用,以及由促进到胁迫的时间拐点;该研究也为基于卫星遥感监测区域尺度植物受酸胁迫提供了借鉴,同时为相关部门制定酸雨政策提供了科学依据。     

植被叶片光谱特征对烟煤病胁迫程度的响应模型研究

烟煤病是我国南方热带、亚热带地区一种非常普遍的植物病害,对我国农业生产造成巨大危害,对其监测预报是实施有效治理措施的重要基础和依据。为建立以高光谱数据为基础的烟煤病严重程度反演模型,在重庆北碚城区采集50个银木叶片样本,利用ASD FieldSpec HandHeld光谱仪获取高光谱数据,通过数码相机和ENVI软件获取叶面积数据,将银木叶片烟煤病面积与整个叶片面积的比例作为烟煤病的严重程度,建立相关性最大波段的烟煤病反演模型,探究烟煤病严重程度与光谱曲线之间可能存在的关系。结果表明： 单叶尺度下,健康叶片在560 nm波段附近有明显的反射峰,随着烟煤病严重程度增大,反射峰逐渐消失, 在可见光与近红外波段,总体上光谱反射率与烟煤病病情严重程度呈负相关性。500～650和720～850 nm为烟煤病的光谱敏感波段,其中相关度最大值点为550 nm波段,相关系数达到-0.72。在烟煤病严重程度与叶片波段原始光谱信息及多波段组合关系研究中,单叶尺度下785 nm波段高光谱参数与烟煤病严重程度建立的回归模型的决定系数(R2)最大,为0.875。通过模型的显著性检验和预测精度检验, 785nm 处的光谱反射率建立的二次曲线模型为最优。证明在单叶尺度下,基于785 nm波段的二次曲线模型反演烟煤病的效果较为理想。     

Analysis of the Volatile Components in the Leaves of Cinna-momum camphora by Static Headspace Gas Chromatography Mass Spectrometry Combined with Accurate Weight Measurement

The volatile components in the leaves of C. camphora were analyzed by static headspace‐gas chromatography/mass spectrometry (HS‐GC‐MS) combined with accurate weight measurement. Accurate weight measurement obtained by Time‐of‐Flight mass spectrometry (TOF‐MS) helped to confirm the identification of volatiles in the analysis. 59 volatile components in the leaves of C. camphora were identified, which mainly included cis‐3‐hexen‐1‐ol (5.6%), 3‐hexen‐1‐ol, acetate (Z) (11.1%), β‐caryophyllene (15.4%), bicyclogermarene (8.4%), trans‐nerolidol (19.5%) and 9‐oxofarnesol (7.7%). The results show that method using HS‐GC‐MS combined with accurate weight measurement achieves reliable identification and has extensive application in the analysis of volatile components present in complex samples.     

川桂叶中黄酮类化合物的提取与测定

采用加热回流法提取川桂叶中的黄酮类化合物,建立了川桂叶中总黄酮含量测定的光谱分析方法。结果表明：以芦丁为标准品,用NaNO2-Al（NO3）3-NaOH显色法可测定川桂叶中总黄酮的含量,该方法的精密度和准确度均较高,相对标准偏差为0.63%,方法的回收率为97.18%—102.20%。通过正交试验优化,得到提取川桂叶中黄酮类化合物的最佳工艺条件是：用体积分数为70%的乙醇作溶剂,在固液比1∶20（g/mL）、提取温度80℃的条件下提取1.5h,连续提取2次。测得川桂叶中总黄酮含量为22.53mg·g^-1。     

Efficient approach for the extraction of proanthocyanidins from Cinnamomum longepaniculatum leaves using ultrasonic irradiation and an evaluation of their inhibition activity on digestive enzymes and antioxidant activity in vitro

Proanthocyanidins were separated for the first time from Cinnamomum longepaniculatum leaves. An experiment‐based extraction strategy was used to research the efficiency of an ultrasound‐assisted method for proanthocyanidins extraction. The Plackett–Burman design results revealed that the ultrasonication time, ultrasonic power and liquid/solid ratio were the most significant parameters among the six variables in the extraction process. Upon further optimization of the Box–Behnken design, the optimal conditions were obtained as follows: extraction temperature, 100°C; ethanol concentration, 70%; pH 5; ultrasonication power, 660 W; ultrasonication time, 44 min; liquid/solid ratio, 20 mL/g. Under the obtained conditions, the extraction yield of the proanthocyanidins using the ultrasonic‐assisted method was 7.88 ± 0.21 mg/g, which is higher than that obtained using traditional methods. The phloroglucinolysis products of the proanthocyanidins, including the terminal units and derivatives from the extension units, were tentatively identified using a liquid chromatography with tandem mass spectrometry analysis. Cinnamomum longepaniculatum proanthocyanidins have promising antioxidant and anti‐nutritional properties. In summary, an ultrasound‐assisted method in combination with a response surface experimental design is an efficient methodology for the sufficient isolation of proanthocyanidins from Cinnamomum longepaniculatum leaves, and this method could be used for the separation of other bioactive compounds.     

Thermal Degradation of Linalool-Chemotype Cinnamomum osmophloeum Leaf Essential Oil and Its Stabilization by Microencapsulation with β-Cyclodextrin

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with β-cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including β-myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool; and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and α-terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the β-cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with β-cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, β-cyclodextrin was fairly stable at 105 °C, and microencapsulation with β-cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.     

新洋茉莉醛的合成

新洋茉莉醛[Helional,2-methyl-3-(1,3-benzedioxol-5-yl)propanal]是一种名贵的单体香料,具有臭氧头香的鲜花香韵和新刈草香气。其合成是用黄樟油制得的胡椒烯丙醛经Raney Ni催化加氢得到新洋茉莉醛粗品,再经硼酸酯、减压分镏得新洋茉莉醛,产率为51％。因为Raney Ni催化选择性较低,     

A sensitive UPLC–MS/MS method for simultaneous determination of polyphenols in rat plasma: Application to a pharmacokinetic study of dispensing granules and standard decoction of Cinnamomum cassia twigs

This study established a rapid and reliable approach using liquid chromatography–tandem mass spectrometry for the simultaneous determination of cinnamic acid, vanillic acid and protocatechuic acid in rat plasma. This is the first report on a comparative pharmacokinetic study of dispensing granules and standard decoction of Cinnamomum cassia twigs in rats. After liquid–liquid extraction by ethyl acetate, the plasma samples were subjected to LC–MS/MS for multiple reaction monitoring. The standard curves showed good linear regression (r² > 0.9991) in the range of 10.0–16000 ng/mL. The intra‐ and inter‐day accuracy and precision were found to be within 15% of the nominal concentration. The recoveries of the three phenolics ranged from 88.7 to 105.7%. Finally, this approach was successfully applied to pharmacokinetic analysis of the three phenolics after oral administration of standard decoction and dispensing granules of C. cassia twigs in rats. Although the values of AUC_0–t of vanillic acid and protocatechuic acid in standard decoction group were larger than those of the dispensing granule group, no significant difference was observed for the two groups. Of note, the elimination rates of vanillic acid were slower in the standard decoction group than the dispensing granule group.     

超声波法提取芹菜叶中多酚类物质

通过单因素试验确定了芹菜叶中多酚类物质较佳的超声波提取工艺条件为:300Hz超声波振荡,提取剂为85%乙醇溶液,料液比为0.8g/10mL,提取时间50min,提取温度40℃。通过分光光度法测定了芹菜叶中多酚类物质的含量为3.0%,即30mg/g。