气相色谱-质谱法对当归及其炮制品挥发油的指纹图谱和潜在标志物研究

建立了一种基于气相色谱-质谱技术(GC-MS)的化学指纹图谱,以发现当归及其不同炮制品潜在标志物的方法.利用GC-MS获得当归及其不同炮制品挥发油化学指纹图谱,对产生的75样本×259变量数据进行归一化、修正80％规则和数据缩放等方法预处理,通过正交校正偏最小二乘法(OPLS)模式识别方法对样品进行模式识别,根据模型的变量重要性因子(VIP)和非参数检验结果筛选出12个潜在标志物.经相关分析和结构鉴定,其中11个化合物分别被鉴定为丁内酯、萜烯醇、6-丁基-1,4环庚二烯、2-壬酮、6-十一烷酮、2-甲氧基苯酚、δ-榄香烯、4,5,6,7-四甲基苯酞、Z-丁烯基酞内酯、亚油酸甲酯、1,7-异丙基-4-甲基-1,4,5,6,7,7a-六氢-2H-茚-2-酮.     

潮州老香黄、老药桔中矿物质元素的测定

潮州老香黄、老药桔是潮州凉果特产中的极品,但对于这两类凉果的研究工作却很少。用火焰原子吸收法测定了老香黄、老药桔中锌,锰,镉,钙,铜,镍,钴等微量元素的含量。本结果可供生产商作参考,以便对某些含量过高的有害元素在生产过程进行有效的控制,也可作为营养分析的参考依据,为其产品的进一步开发提供科学依据。     

基于超高效液相色谱-紫外检测定量指纹图谱结合化学模式识别的复方金钱草颗粒质量评价

复方金钱草颗粒具有利尿、抑制泌尿系结石形成、抗炎、抗氧化作用,且具有较大的市场需求。因此,采用超高效液相色谱-紫外检测(UPLC-UV)法建立定量指纹图谱,并结合化学模式识别技术对不同年份的复方金钱草颗粒进行质量评价,可为其质量控制提供依据。采用聚类分析(HCA)和主成分分析(PCA)等化学模式识别技术对35批复方金钱草颗粒样品的指纹图谱数据进行分析,筛选出质量差异标志物芒果苷和异芒果苷,并对二者进行含量测定。在复方金钱草颗粒指纹图谱中共指认出12个共有峰,且35批样品的相似度均在0.952以上。在HCA中,将35批样品分为了两类,其中2018年和2019年的样品为一类,2020年和2021年的样品为一类。此外,PCA结果显示了与聚类分析相同的聚类趋势。在此基础上,进一步通过正交偏最小二乘法分析 (OPLS-DA)筛选出了导致2018年、2019年与2020年、2021年的样品产生差异的差异标志物芒果苷和异芒果苷。以两个差异标志物芒果苷和异芒果苷为指标进行含量测定,结果显示色谱峰的分离度良好,线性关系良好,平均加标回收率分别为101.7%~105.6%和103.4%~105.5%,且相对标准偏差(RSD)均低于1.43%。在35批样品中,2020年、2021年的样品与2018年、2019年的样品相比,芒果苷与异芒果苷含量更高且波动范围更小。该研究建立了准确、可靠的复方金钱草颗粒质控方法,实现了对不同年份的复方金钱草颗粒样品合理、有效的质量评价,可为建立更系统、更全面的质量控制标准提供借鉴与参考。     

基于靶向质谱代谢组学的广陈皮年份鉴别研究

广陈皮的药用价值随着陈化年份增加而逐渐提高,其价格也随之上涨,导致市场上广陈皮年份欺诈问题严重。针对此问题,本研究选取陈化年份为7～17年的广陈皮作为研究对象,采用基于靶向质谱代谢组学的方法进行年份鉴别。首先,以《中国药典》规定的橙皮苷、橘皮素和川陈皮素等质量评价指标为靶向分析物,与已有研究结果进行对比,评估样品的真实性;然后,利用靶向质谱代谢组学方法计算广陈皮中6种黄酮类化合物的绝对含量以及63种黄酮类化合物和94种黄酮类与非黄酮类化合物的相对含量,结合正交偏最小二乘法判别分析（OPLS-DA）,筛选广陈皮中与年份相关的标志代谢物,用以鉴别广陈皮年份。研究结果表明,仅依赖于中国药典规定的3个质量评价指标在内的黄酮类代谢物无法有效鉴别广陈皮的陈化年份,而通过靶向质谱代谢组学方法成功地从广陈皮的94种黄酮类和非黄酮类化合物中筛选得到32种潜在的年份代谢标志物,其中包括荭草素和诺米林等化合物。这些标志物的发现为区分不同年份的广陈皮提供了参考,有望应用于广陈皮的年份鉴别。     

火焰原子吸收光谱法分析香青兰中微量元素的溶出特性及化学形态

结合香青兰的药用功效,对其铜、锌、锰、铁、镁、镍6种微量元素的含量和形态进行了分析.分别用0.45 μm滤膜、D101型大孔吸附树脂,将香青兰水煎液中铜、锌、锰、铁、镁、镍分为悬浮态和可溶态、有机态和无机态;并采取正辛醇-水分配体系模拟水煎液中铜、锌、锰、铁、镁、镍在人体胃肠中的分配情况,建立了上述6种元素的4种形态分离分析方法,用火焰原子吸收光谱法测定6种微量元素的含量、分布及其在不同溶剂中的溶出特性和化学形态.结果表明,方法的回收率在92%～106%范围内,相对标准偏差均在3.8%以下,铜、锌、锰、铁、镁、镍是各以某种形态为主的多种形态共存的混杂体系.     

基于UPLC-Q-TOF MS技术的陈皮陈化年份鉴别方法研究

建立了一种陈皮陈化年份的鉴定方法。利用超高效液相色谱-四极杆串联飞行时间质谱(UPLC-Q-TOF MS)对陈皮的主要化学成分进行鉴定,研究了不同陈化年份陈皮样品中化学成分的变化规律,结合统计分析方法发现了6个同分异构体在陈皮陈化过程中的相互转化规律。结果表明,6个分子式为C₂₀H₂₂O₇的五甲氧基黄烷酮同分异构体中,前3个化合物含量随年份的增加而降低,后3个化合物含量随年份的增加而升高,其比值与陈化年份具有显著的线性关系。利用该6个特征性成分的转化因子(S),建立了陈皮陈化年份计算模型,相关系数(r²)为0.90。训练集样品的年份预测误差均不大于2年。盲样测试结果中90.0%样品的年份预测误差不大于2年。该方法准确可靠,为陈皮陈化年份的鉴定提供了科学依据。     

RP-HPLC法测定不同生长年份栽培藏木香主要活性成分含量

采用RP-HPLC法测定不同生长年份栽培藏木香主要活性成分土木香内酯和异土木香内酯含量,并对其含量进行比较。异土木香内酯和土木香内酯质量浓度在9.34~46.67μg/mL,7.34~36.67μg/mL范围内与色谱峰面积均呈良好的线形关系,平均回收率分别为100.61%和100.34%,RSD为2.11%和1.89%。方法可用于栽培藏木香主要活性成分含量测定。测定结果表明,异土木香内酯含量高于土木香内酯,总量随生长年份不断增高,并主要存在于根部,茎叶未检测到。     

基于聚类分析的初三化学学业质量发展研究

以2013-2016年广州市各区（县级市）中考化学成绩的4种数据为指标，运用聚类分析研究广州市区域初三化学学业质量的发展状况。研究发现各区（县级市）主要分为3大类，部分区在不同年份的类别中移动，倾向于建立一个包括越来越多区域的第1大类。广州市区域初三化学学业质量逐步向优质均衡发展。系统的中学生化学探究活动和化学教师研训活动是实现这一发展的重要原因。     

不同产地白芷药材高效液相色谱指纹图谱研究

本文采用高效液相色谱-二极管阵列检测器(HPLC-DAD)法建立中药白芷的指纹图谱.应用化学计量学中两种不同的模式识别方法(主成分分析法和系统聚类分析法)对实验数据进行处理,以找出来自三个不同产地30个中药白芷样品间的相似性及差异性.两种模式识别方法均能成功地按样品的来源将不同产地的样品正确分类.建立了不同产地中药白芷的识别方法,该方法能有效地控制中药白芷的质量,并能为其它中药产品的化学模式识别提供参考.     

HSSPME-GC-MS联用分析墨吉对虾储藏过程挥发性有机物特征的变化

建立了顶空固相微萃取-气相色谱-质谱联用分析墨吉对虾挥发性有机物(VOCs)的方法,结合化学计量学方法解析了墨吉对虾储藏过程中VOCs特征的变化,初步研究了VOCs特征变化与其鲜度的关系.采用上述方法,在新鲜和变质墨吉对虾样品中分别检测到22种和16种VOCs组分.采用主成分分析解析新鲜、储藏过程及变质阶段对虾样品的VOCs色谱特征,结果表明墨吉对虾变质前后VOCs特征有明显不同的聚类规律,且对虾样品储藏过程中VOCs特征从新鲜到变质状态呈现逐步过渡的趋势,对虾储藏过程VOCs特征的变化可以提供更加准确的鲜度变化预警信息.最后,采用共有模式统计对比了新鲜和变质墨吉对虾VOCs特征聚类数据,获得对样品变质前后VOCs特征差异贡献前5位VOCs,可作为潜在的鲜度判别预警VOCs标志物.     

Total synthesis of naturally occurring 5,6,7- and 5,7,8-trioxygenated coumarins

The synthesis of five naturally occurring polyoxygenated coumarins is described. It concerns two 5,6,7-trioxygenated coumarins, i.e., 6-hydroxy-5,7-dimethoxycoumarin (fraxinol) 1 and 5,6,7-trimethoxycoumarin 2, and three 5,7,8-trioxygenated coumarins, i.e., 8-hydroxy-5,7-dimethoxycoumarin (leptodactylone) 3, 5,7,8-trimethoxycoumarin 4 and 8-(3-methyl-2-butenyloxy)-5,7-dimethoxycoumarin (artanin) 5. Key feature of the synthetic pathway is the synthesis of suitable tetraoxygenated benzaldehydes, which are then converted to the corresponding coumarins via a Wittig reaction.     

ISOLATION and CHARACTERIZATION OF THE PHOTOADDUCTS OF 5,7-DIMETHOXYCOUMARIN and ADENOSINE

The isolation and structural characterization of the photoadducts of 5,7-dimethoxycoumarin and adenosine are described. Two of the major photoadducts were isolated by preparative column chromatography and reverse-phase high performance liquid chromatography. Structure of the products was determined by UV, FT-IR, mass spectrometry, ¹H NMR and ¹³C NMR studies, including the homonuclear decoupling, COSY method and DEPT experiments. The photoadducts were not C₄-cycloadducts but simple addition products in contrast to pyrimidine base adducts. Covalent bonds were formed between the carbon-3 or carbon-4 of the pyrone ring of 5,7-dimethoxycoumarin and the carbon-5'of ribose ring in adenosine.     

PHOTOCYCLOADDITION OF 5,7-DIMETHOXYCOUMARIN TO THYMINE

Abstract— C₄-_-Photocycloaddition of 5,7-dimethoxycoumarin (DMC) to thymine (λ≥ 300 nm) was studied in dioxane-water solution, in aqueous frozen state, and solid film state. The major product was isolated and characterized by physical methods. Elemental analysis data, spectral analyses, and photo-splitting of the product indicate the product to be a 1:l C₄-_-cycloadduct of DMC and thymine.     

UPLC-Q-TOF-MS analysis of non-volatile migrants from new active packaging materials

Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07?±?0.01?μg/g), carvacrol (0.31?±?0.03?μg/g) and citral (0.20?±?0.01?μg/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials.     

Screening and characterizing the quality markers of Selaginella tamariscina (P. Beauv.) Spring using metabonomics and molecular networking

Quality control of traditional Chinese medicine (TCM) should be linked with the authentication and efficacy of TCM. Selaginella tamariscina is a frequently used traditional Chinese herbal medicine. However, its quality control is still difficult due to its multiple adulterants. We established quality markers (Q-markers) of S. tamariscina by using metabolomics, molecular networking and network pharmacology to improve the authenticity study and quality control of S. tamariscina. In this study, ultra high performance liquid chromatography-mass spectrum (UHPLC-MS) coupled with multivariate statistical analyses was applied to distinguish between S. tamariscina samples and their confusing adulterants. Principal component analysis, hierarchical clustering analysis (PCA), hierarchical clustering analysis (HCA) and partial least squares discriminant analysis (PLS-DA) were employed to screen the distinguishing markers from S. tamariscina samples and their adulterants. The top-2 distinguishing markers were isolated from S. tamariscina and identified by molecular networking together with nuclear magnetic resonance spectroscopy (NMR). Network pharmacology predicted the bioactivity and cytotoxicity of the top-2 distinguishing markers. The top-2 distinguishing markers were adopted as Q-markers of S. tamariscina for content determination. Based on the results of ultra performance liquid chromatography-quardrupole-time of flight mass spectrometry (UHPLC-QTOF-MS) metabolomics, we revealed that selaginellins could only be detected in S. tamariscina samples and contributed greatly to discriminating S. tamariscina samples from their confused species. The top-2 distinguishing markers were isolated and purified from S. tamariscina extract. Then, they were further identified as selaginellin and selaginellin A by molecular networking and NMR. Network pharmacology predicted the antitumor activity of selaginellin and selaginellin A, while the cytotoxicity assay verified their bioactivity. In conclusion, selaginellin and selaginellin A were selected as Q-markers for the determination and quality evaluation of S. tamariscina based on ultra performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QQQ-MS). The ranges of the concentrations of selaginellin and selaginellin A were 41.57–44.89 μg/g and 15.09–16.75 μg/g, respectively. This study provides a novel strategy combining Ultra performance liquid chromatography mass spectrometry based (UHPLC-MS-based) metabolomics with molecular networking for rapid species identification of S. tamariscina and discovery of the Q-markers of TCM.     

Isolation and structure elucidation of a new prenylcoumarin from Murraya paniculata var. omphalocarpa (Rutaceae)

A new C-8 prenylated 5,7-dimethoxycoumarin named omphamurrayin was isolated from the leaves of Murraya paniculata var. omphalocarpa, and its structure was established as 5,7-dimethoxy-8-(1-oxo-2-senecioyl-3-methyl-3-butenyl)-2H-1-benzopyran-2-one on the basis of the spectroscopic evidence. The taxonomic status of M. paniculata var. omphalocarpa is briefly discussed, along with its synonymity to M. paniculata from the chemosystematic viewpoint.     

STUDIES ON THE PHOTOTOXICITY OF COUMARIN DERIVATIVES — I. PHOTOCYCLODIMERIZATION OF 5,7-DIMETHOXYCOUMARIN

Abstract— 5,7-DimethoxJtcoumarin (DMC) dimerizes through the C₄-photo-cycloaddition of 3,4-double bonds to form a syn head-to-tail dimer on direct irradiation ( Λ≥ 300 nm) in acetonitrile or benzene solution. The quantum yield of the photocyclodimerization in acetonitrile is 0.068 which is greater than that of coumarin.
In the presence of triplet sensitizers such as benzophenone, 5,7-dimethoxycoumarin forms an anti dimer with the quantum yield greater than 0.08. The structure of the photodimers has been elucidated by IR, UV, NMR, and mass spectrometry. The results of luminescence studies, triplet quenching and sensitization revealed that the syn head-to-tail dimer was formed via an excited singlet precursor, while the anti dimer was formed via the excited triplet state.     

Chemical composition of essential oil and in vitro antioxidant activities of the essential oil and methanol extracts of Eucalyptus loxophleba

This study was designed to examine the chemical composition of the essential oil and the antioxidant activity of the essential oil and methanol extracts of Eucalyptus loxophleba Benth. subsp. The chemical composition of the essential oil of the leaves of E. loxophleba was analysed by GC and GC/MS. The main constituents of the oil were found to be 1,8-cineole (39.4%), methyl amyl acetate (19.8%) and aromadendrene (10%). Antioxidant activities of the samples were determined by two different test systems namely DPPH and β-carotene/linoleic acid. In the DPPH system, the highest radical-scavenging activity was shown by the polar subfraction of the methanol extract (15.2?±?1.7?μg?mL?1). Also, in the second case, the inhibition capacity (%) of the polar subfraction (94.1?±?1.3) was found to be stronger. In addition, the amounts of total phenol components in the polar subfraction (273.0?±?2.6?μg?mg?1) and nonpolar subfraction (146.3?±?2.5?μg?mg?1) were determined.     

HPLC-DAD结合交替三线性分解二阶校正方法进行中药葛根中主要有效成分同时测定

应用高效液相色谱-二极管阵列联用仪(HPLC-DAD)结合基于交替三线性分解(ATLD)算法的二阶校正方法快速测定了中药葛根样中主要活性成分葛根素、大豆苷和大豆苷元的含量,实现了同时定量分析.色谱条件:甲醇-水(体积比为53∶47),检测波长范围为190～380nm,柱温为30℃,流速为1.0mL/min,进样量为20.0μL.预测的实际样中三种目标分析组分葛根素、大豆苷、大豆苷元的含量分别为(0.465±0.023),(0.553±0.015)和(0.098±0.005)mg/g,它们的加标回收率分别为(101.1±3.2)%,(100.4±6.4)%和(100.1±4.9)%.     

PHOTOCYCLOADDITION REACTION OF 5,7-DIMETHOXYCOUMARIN TO THYMIDINE

Abstract— The photocycloaddition reaction of 5,7-dimethoxycoumarin to thymidine on direct irradiation (λ > 300 nm) is studied as a model for photosensitization reaction of furocoumarins. The major photoadducts were isolated by silica gel column and gel permeation chromatography. Each component of the photoadducts was further separated by reverse phase, paired-ion high performance liquid chromatography. The structure of these photoproducts isolated is consistent with 1:1 C₄-cycloadducts in accordance with characteristics of their UV, IR, NMR and mass spectra and elemental analysis data. The stereochemistry of each isomer was studied by Fourier transform NMR, UV and IR spectra. The fraction C has the anti head-to-tail configuration and the fraction D has the configuration of anti head-to-head. The fractions A and B probably have the syn configuration.