超高效液相色谱-串联质谱法测定红薯叶中15种功效成分

建立了超高效液相色谱-串联质谱（UHPLC-MS/MS）快速测定红薯叶中15种功效成分的分析方法。样品用80%（v/v）甲醇水溶液提取后,采用C₁₈色谱柱（100 mm×2.1 mm,1.8 μm）进行分离,以乙腈-0.15%（v/v）甲酸水溶液为流动相进行梯度洗脱,在电喷雾电离（ESI）源、负离子扫描模式下,通过多反应监测（MRM）模式检测各物质分子的离子峰。在各自的范围内15种功效成分线性关系良好,相关系数（r）为0.9995~0.9998;在3个加标水平下,15种化合物的回收率为82.2%~131.4%,相对标准偏差为3.6%~8.3%;方法的检出限为0.13~0.64 μg/L。该方法前处理简单,灵敏度高,适用于红薯叶中功效组分的快速分析,定量分析结果显示咖啡奎宁酸类物质是红薯叶中的主要功效成分。     

Phytochemical analysis of non-polar solvent extracts of the Wisteria sinensis leaves

A comparative study on the phytochemical composition of the n-hexane and chloroform extracts from Wisteria sinensis leaves collected in June and October is described. Continuous extraction in Soxhlet apparatus, as well as ultrasound-assisted technique, was used for the preparation of the extracts. All the extracts were analysed by GC/MS method. As a result, α-tocopherol was identified as the main component (56%) of the extracts from October leaves, whereas, β-sitosterol was identified as the main compound (47%) in the extracts from the June leaves. Additionally, pure α-tocopherol was isolated from n-hexane extract of the October leaves using column chromatography. A total of 6.25 mg of α-tocopherol was isolated from 1 g of dried leaves. The presence of the vitamin E in extracts from W. sinensis leaves is described here for the first time.     

烟草中钾含量测定的研究

研究了在聚乙烯醇介质中,利用钾离子与四苯硼钠形成稳定的胶体沉淀可测定钾含量,钾量在0－1.0mg/25mL内符合比耳定律。方法可用于烟草制品中 钾含量的测定,结果满意。     

Fingerprint and multicomponent quantitative analysis for the quality evaluation of Sibiraea angustata leaves by HPLC-DAD and HPLC-ESI-MS/MS combined with chemometrics

Sibiraea angustata leaves, known as a traditional Tibetan medicine, have been specially used in the treatment of indigestion and obesity. In the study, a simple and sensitive high-performance liquid chromatography (HPLC) method with a diode array detector (DAD) was established to solve the problem of lacking quality standard of S. angustata leaves, including the fingerprint analysis and quantification of six characteristic components. The analytical method was validated for linearity, repeatability, stability, recovery, and specificity. Seventeen raw samples and 1 processed sample of S. angustata leaves were collected from different locations of China to establish the fingerprint. The chemometric methods, including similarity analysis (SA), principal component analysis (PCA), and hierarchical clustering analysis (HCA), were applied to distinguish the 18 batches of S. angustata samples. The results successfully sorted these samples into five clusters and kept in line with each other. According to the result of the fingerprint analysis, 21 peaks were extracted to be the common peaks and most of them were identified by mass spectrometry (MS) with electron-spray ionization (ESI) in the negative mode. Meanwhile, the loading plot of PCA further indicated that the peaks of neochlorogenic acid, chlorogenic acid, ferulic acid, rutin, hyperin, and isoquercitrin played a greater role in the discrimination among the 21 peaks. So the six components mentioned above were investigated as index constituents to evaluate the quality of S. angustata leaves from different locations. The study demonstrated that the developed new method was a beneficial approach for authentication and quality evaluation of S. angustata leaves.     

A rapid method for the determination of methoprene in tobacco by high performance liquid chromatography

Summary A rapid sample preparation procedure combined with a short reversed-phase HPLC separation for the quantitation of methoprene residue in tobacco samples is described. A ground tobacco sample of 0.5 g is mixed with 3 mL of 2-propanol. The mixture is extracted for twelve minutes with the aid of sonication at an elevated temperature (45–55°C) and then filtered through a 0.45 m disposable filter prior to injection on HPLC. No sample cleanup or solvent evaporation step is required. Chromatographic analysis is performed on a C-18 column and the analysis time is 12.5 minutes. The detection limit for methoprene in tobacco samples is one part per million (g/g).     

Quantitative images of metals in plant tissues measured by laser ablation inductively coupled plasma mass spectrometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for quantitative imaging of toxic and essential elements in thin sections (thickness of 30 or 40 μm) of tobacco plant tissues. Two-dimensional images of Mg, Fe, Mn, Zn, Cu, Cd, Rh, Pt and Pb in leaves, shoots and roots of tobacco were produced. Sections of the plant tissues (fixed onto glass slides) were scanned by a focused beam of a Nd:YAG laser in a laser ablation chamber. The ablated material was transported with argon as carrier gas to the ICP ion source at a quadrupole ICP-MS instrument. Ion intensities of the investigated elements were measured together with ¹³C⁺, ³³S⁺ and ³⁴S⁺ within the entire plant tissue section. Matrix matching standards (prepared using powder of dried tobacco leaves) were used to constitute calibration curves, whereas the regression coefficient of the attained calibration curves was typically 0.99. The variability of LA-ICP-MS process, sample heterogeneity and water content in the sample were corrected by using ¹³C⁺ as internal standard. Quantitative imaging of the selected elements revealed their inhomogeneous distribution in leaves, shoots and roots.     

荧光法测定香烟烟气中总的多环芳烃含量

有机溶剂萃取不同香烟烟气焦油中有机物 ,用荧光法分析了烟草的总体特征光谱 ,同时以多环芳烃菲作参比 ,定量分析了各种品牌香烟在去掉过滤嘴和保留过滤嘴条件下 ,烟气在溶剂中的多环芳烃含量 ,为卷烟品质、烟气中有害物质的评价提供了一种实用的测定方法     

Olive-Derived Triterpenes Suppress SARS COV-2 Main Protease: A Promising Scaffold for Future Therapeutics

SARS CoV-2 pandemic is still considered a global health disaster, and newly emerged variants keep growing. A number of promising vaccines have been recently developed as a protective measure; however, cost-effective treatments are also of great importance to support this critical situation. Previously, betulinic acid has shown promising antiviral activity against SARS CoV via targeting its main protease. Herein, we investigated the inhibitory potential of this compound together with three other triterpene congeners (i.e., ursolic acid, maslinic acid, and betulin) derived from olive leaves against the viral main protease (M^pro) of the currently widespread SARS CoV-2. Interestingly, betulinic, ursolic, and maslinic acids showed significant inhibitory activity (IC₅₀ = 3.22–14.55 µM), while betulin was far less active (IC₅₀ = 89.67 µM). A comprehensive in-silico analysis (i.e., ensemble docking, molecular dynamic simulation, and binding-free energy calculation) was then performed to describe the binding mode of these compounds with the enzyme catalytic active site and determine the main essential structural features required for their inhibitory activity. Results presented in this communication indicated that this class of compounds could be considered as a promising lead scaffold for developing cost-effective anti-SARS CoV-2 therapeutics.     

GC-MS同时测定番石榴叶中的齐墩果酸和熊果酸

建立了测定番石榴叶中齐墩果酸和熊果酸的气相色谱-质谱（GC-MS）方法.以双（三甲硅烷）三氟乙酰胺（BSTFA）为衍生化试剂,将齐墩果酸和熊果酸制成三甲基硅烷衍生物后,在DB-5 MS毛细管柱上进行分离.柱升温程序为：柱初温100 ℃,恒温保持2 min, 以10 ℃/min的速度升温至300 ℃,保持14 min.通过与标准样品对照比较保留时间和质谱确认样品中齐墩果酸和熊果酸的色谱峰.以峰面积进行定量测定,齐墩果酸和熊果酸的线性范围分别为4.1～102 μg/mL和4.7～114 μg/mL,回收率分别为77.1%和89.4%,6次平行测定的相对标准偏差分别为3.7%和3.5%.     

Liquid chromatography/mass spectrometry-based metabolic profiling to elucidate chemical differences of tobacco leaves between Zimbabwe and China

An approach was developed for extracting and analyzing the chemical components of tobacco leaves based on solvent extraction and rapid & resolution liquid chromatography/quadrupole time-of-flight mass spectrometry analysis. Two solvents with different polarities were used to extract hydrophilic components and hydrophobic components, respectively, the combined analytical data can provide a "global" view of metabolites. Based on the evaluation of parallel samples, it was found that this approach provided good repeatability, accurate and reliable profiling data, and is suitable for the metabolomics study of tobacco leaves. In order to find the chemical component differences of tobacco leaves, 56 samples from Zimbabwe and China were analyzed using the developed method. The metabolite data were processed by multivariate statistic technique; an obvious group classification between Zimbabwe and China was observed, 14 significantly changed compounds were found, and 9 of them were identified.