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Oh J, Bowling JJ, Carroll JF, Demirci B, Başer KHC, Leininger TD, Bernier UR, Hamann MT. Natural product studies of U.S. endangered plants: volatile components of Lindera melissifolia (Lauraceae) repel mosquitoes and ticks. PHYTOCHEMISTRY 2012; 80:28-36. [PMID: 22704653 PMCID: PMC4144860 DOI: 10.1016/j.phytochem.2012.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 03/27/2012] [Accepted: 05/01/2012] [Indexed: 06/01/2023]
Abstract
The number of endangered plant species in the U.S. is significant, yet studies aimed towards utilizing these plants are limited. Ticks and mosquitoes are vectors of significant pathogenic diseases of humans. Repellents are critical means of personal protection against biting arthropods and disease transmission. The essential oil and solvent extracts from Lindera melissifolia (Walt.) Blume (Lauraceae) (pondberry) drupes were gathered and analyzed by GC and GC-MS. The essential oil obtained from this endangered plant showed a significant dose dependent repellency of ticks and a moderate mosquito repellent effect while the subsequent hexanes extract was completely ineffective. Fractional freezing enriched the tick repellent components of the essential oil. Several known tick repellent components were recognized by the GC-MS comparison of the resulting fractions and β-caryophyllene, α-humulene, germacrene D and β-elemene warrant evaluations for tick repellency. Identifying pondberry as a potential renewable source for a broad spectrum repellent supports efforts to conserve similar U.S. endangered or threatened plant species.
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Xu YJ, Foubert K, Dhooghe L, Lemière F, Maregesi S, Coleman CM, Zou Y, Ferreira D, Apers S, Pieters L. Rapid isolation and identification of minor natural products by LC-MS, LC-SPE-NMR and ECD: isoflavanones, biflavanones and bisdihydrocoumarins from Ormocarpum kirkii. PHYTOCHEMISTRY 2012; 79:121-128. [PMID: 22575670 DOI: 10.1016/j.phytochem.2012.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 04/02/2012] [Accepted: 04/05/2012] [Indexed: 05/31/2023]
Abstract
The combination of the hyphenated techniques LC-MS and LC-SPE-NMR constitutes a powerful platform for the rapid isolation and identification of minor components from natural sources. Electronic circular dichroism (ECD) is a useful tool to determine the absolute configuration of small quantities of chiral molecules. In order to search for minor constituents present in an Ormocarpum kirkii extract, these techniques were applied for the separation and structure elucidation of a series of isoflavanones, biflavanones and biscoumarins. After optimization of chromatographic conditions and subsequent isolation, MS and 1D and 2D NMR data were collected. Experimental and calculated ECD spectra were used in conjunction with NMR data to confirm the absolute configuration of these compounds. Eight compounds were identified for the first time and six have been previously reported. The present approach offers a strategy for accelerating research on natural products.
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Edwards JE, Brown PN, Talent N, Dickinson TA, Shipley PR. A review of the chemistry of the genus Crataegus. PHYTOCHEMISTRY 2012; 79:5-26. [PMID: 22608128 DOI: 10.1016/j.phytochem.2012.04.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 12/09/2011] [Accepted: 04/17/2012] [Indexed: 05/07/2023]
Abstract
Since the 1800s, natural health products that contain hawthorn (Crataegus spp.) have been used in North America for the treatment of heart problems such as hypertension, angina, arrhythmia, and congestive heart failure. Traditionally, Native American tribes used hawthorn (Crataegus spp.) to treat gastrointestinal ailments and heart problems, and consumed the fruit as food. Hawthorn also has a long history of use in Europe and China for food, and in traditional medicine. Investigations of Crataegus spp. typically focus on the identification and quantification of flavonoids and anthocyanins, which have been shown to have pharmacological activity. The main flavonoids found in Crataegus spp. are hyperoside, vitexin, and additional glycosylated derivatives of these compounds. Reviewed herein are the botany, ethnobotany, and traditional use of hawthorn while focusing on the phytochemicals that have been reported in Crataegus species, and the variation in the described chemistry between individual species.
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Pauli GF, Chen SN, Friesen JB, McAlpine JB, Jaki BU. Analysis and purification of bioactive natural products: the AnaPurNa study. JOURNAL OF NATURAL PRODUCTS 2012; 75:1243-55. [PMID: 22620854 PMCID: PMC3381453 DOI: 10.1021/np300066q] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Based on a meta-analysis of data mined from almost 2000 publications on bioactive natural products (NPs) from >80000 pages of 13 different journals published in 1998-1999, 2004-2005, and 2009-2010, the aim of this systematic review is to provide both a survey of the status quo and a perspective for analytical methodology used for isolation and purity assessment of bioactive NPs. The study provides numerical measures of the common means of sourcing NPs, the chromatographic methodology employed for NP purification, and the role of spectroscopy and purity assessment in NP characterization. A link is proposed between the observed use of various analytical methodologies, the challenges posed by the complexity of metabolomes, and the inescapable residual complexity of purified NPs and their biological assessment. The data provide inspiration for the development of innovative methods for NP analysis as a means of advancing the role of naturally occurring compounds as a viable source of biologically active agents with relevance for human health and global benefit.
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Hou Y, Braun DR, Michel CR, Klassen J, Adnani N, Wyche TP, Bugni TS. Microbial strain prioritization using metabolomics tools for the discovery of natural products. Anal Chem 2012; 84:4277-83. [PMID: 22519562 PMCID: PMC3352271 DOI: 10.1021/ac202623g] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 04/22/2012] [Indexed: 12/16/2022]
Abstract
Natural products profoundly impact many research areas, including medicine, organic chemistry, and cell biology. However, discovery of new natural products suffers from a lack of high throughput analytical techniques capable of identifying structural novelty in the face of a high degree of chemical redundancy. Methods to select bacterial strains for drug discovery have historically been based on phenotypic qualities or genetic differences and have not been based on laboratory production of secondary metabolites. Therefore, untargeted LC/MS-based secondary metabolomics was evaluated to rapidly and efficiently analyze marine-derived bacterial natural products using LC/MS-principal component analysis (PCA). A major goal of this work was to demonstrate that LC/MS-PCA was effective for strain prioritization in a drug discovery program. As proof of concept, we evaluated LC/MS-PCA for strain selection to support drug discovery, for the discovery of unique natural products, and for rapid assessment of regulation of natural product production.
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Cappiello A, Tirillini B, Famiglini G, Trufelli H, Termopoli V, Flender C. Determination of natural pyrethrins by liquid chromatography-electron ionisation-mass spectrometry. PHYTOCHEMICAL ANALYSIS : PCA 2012; 23:191-196. [PMID: 21774016 DOI: 10.1002/pca.1342] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 05/03/2011] [Accepted: 05/09/2011] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Pyrethrum extract is a mixture of six insecticidal compounds from the flower heads of Chrysanthemum cinerariaefolium L.. Since they only have low to moderate mammalian toxicity they can be used as natural insecticides in agriculture or to develop low cost and safe dermatological formulations. Because of the thermal instability of pyrethrins, analytical methods based on liquid chromatography (LC) are preferred over those based on gas chromatography (GC). A few applications using LC with mass spectrometry detection are presented in the literature. Current protocols for their characterisation by LC rely on the use of less sophisticated detectors such as UV detection. OBJECTIVE To develop the first liquid chromatography-electron ionisation-mass spectrometry (LC-EI-MS) method for pyrethrins detection and quantitation in pyrethrum extracts. METHODOLOGY A commercial pyrethrum extract and various samples of flower heads from C. cinerariaefolium L. were investigated using reversed-phase nano-liquid chromatography coupled to direct electron ionisation-mass spectrometry (nanoLC-direct EI-MS). The eluted compounds were identified through searches of the US National Institute of Standards and Technology (NIST) library, exploiting the direct EI capability to produce high quality EI mass spectra. RESULTS The method demonstrated satisfactory sensitivity (limit of detection (LOD) range: 0.04-0.38 mg/g), linearity (R² range: 0.9740-0.9983) and precision (RSD% range: 4-13%) for the quantitation of the natural pyrethrins in extracts from C. cinerariaefolium L. CONCLUSION The nanoLC-direct EI-MS technique can be a useful tool for the detection of pyrethrins.
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Adnani N, Michel CR, Bugni TS. Universal quantification of structurally diverse natural products using an evaporative light scattering detector. JOURNAL OF NATURAL PRODUCTS 2012; 75:802-6. [PMID: 22471612 PMCID: PMC3338159 DOI: 10.1021/np300034c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Indexed: 05/31/2023]
Abstract
A lack of good methods for absolute quantification of natural products has limited the accuracy of high-throughput screening. Many currently used methods for quantification are either too slow or not amenable to the structural diversity of natural products. Recent developments in low-temperature evaporative light scattering detectors (ELSD-LT) have overcome several historical limitations of ELSDs, including analyte decomposition and low sensitivity. Primarily, ELSDs have been used for relative quantification and detection of compounds that lack a UV chromophore. In this study, we employ an ELSD-LT for absolute quantification of natural products. Calibration curves were constructed using a weighted least-squares analysis for a diverse set of natural products and other compounds. An average calibration curve was evaluated for the "universal" quantification of natural products. Optimization of ELSD-LT hardware and parameters improved sensitivity and throughput and established the utility of ELSD-LT for quantification of large natural product libraries.
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Straub JO, Gysel D, Kastl U, Klemmer J, Sonderegger M, Studer M. Environmental risk assessment for ancillary substances in biotechnological production of pharmaceuticals. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2012; 31:681-687. [PMID: 22189954 DOI: 10.1002/etc.1733] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 10/13/2011] [Accepted: 11/04/2011] [Indexed: 05/31/2023]
Abstract
An increasing number of pharmaceutical active substances are produced through biotechnological processes. For sustained and safe growth of the host organisms as well as optimal expression, purification, and formulation of the product, biotechnological manufacturing processes need optimal and robust environmental conditions, which are attained through the use of buffers, chelators, and antibiotics, beside nutrients. These ancillary substances are drained with the wastewater to a wastewater treatment plant (WWTP) and are released after treatment with the effluent to receiving waters. The potential risks of such substances to WWTPs and surface waters were investigated. Three common buffers (morpholinoethane sulfonic acid [MES], morpholinopropanesulfonic acid [MOPS], 1,4-piperazine (diethanesulfonic acid) [PIPES]), one chelator (ethylenediaminetetraacetic acid [EDTA]), and one antibiotic (gentamycin) were searched in the literature for environmental data or tested for biodegradability and inhibition of activated sludge as well as acute toxicity to algae, daphnids, and fish. Amounts of the ancillary substances used in the European biotechnological production plants of F. Hoffmann-La Roche Ltd in Basle (Switzerland) and Penzberg (Germany), and actual wastewater fluxes through the respective WWTP, as well as realistic dilution factors for the local receiving water, were documented. Based on this information, site-specific predicted environmental concentrations (PECs) for the WWTPs and surface waters in Basle and Penzberg were extrapolated. These PECs were compared with predicted no effect concentrations (PNECs) for the WWTP and surface waters, derived from sludge inhibition and ecotoxicity results, respectively. For all five ancillary substances investigated, all PEC/PNEC risk characterization ratios are <1, indicating no significant risk to the WWTPs or the receiving waters at both sites.
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Pangallo KC, Reddy CM, Poyton M, Bolotin J, Hofstetter TB. δ¹⁵N enrichment suggests possible source for halogenated 1'-methyl-1,2'-bipyrroles (MBPs). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:2064-2070. [PMID: 22268675 DOI: 10.1021/es203143c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Polyhalogenated 1'-methyl-1,2'-bipyrroles are natural products that biomagnify into upper trophic levels of marine food webs. Here we demonstrate that they are unusually enriched in (15)N (δ(15)N from +19.3‰ to +28.1‰) relative to other biosynthetic organic compounds measured to date and the mammals from which the compounds were isolated. We argue the (15)N enrichment likely stems from enriched precursors and/or fractionation during biosynthesis and is not from MBP degradation. We also consider possible sources of MBPs in light of these results.
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Goodwin CR, Fenn LS, Derewacz DK, Bachmann BO, McLean JA. Structural mass spectrometry: rapid methods for separation and analysis of peptide natural products. JOURNAL OF NATURAL PRODUCTS 2012; 75:48-53. [PMID: 22216918 PMCID: PMC3267852 DOI: 10.1021/np200457r] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A significant challenge in natural product discovery is the initial discrimination of discrete secondary metabolites alongside functionally similar primary metabolic cellular components within complex biological samples. A property that has yet to be fully exploited for natural product identification and characterization is the gas-phase collision cross section, or, more generally, the mobility-mass correlation. Peptide natural products possess many of the properties that distinguish natural products, as they are frequently characterized by a high degree of intramolecular bonding and possess extended and compact conformations among other structural modifications. This report describes a rapid structural mass spectrometry technique based on ion mobility-mass spectrometry for the comparison of peptide natural products to their primary metabolic congeners using mobility-mass correlation. This property is empirically determined using ion mobility-mass spectrometry, applied to the analysis of linear versus modified peptides, and used to discriminate peptide natural products in a crude microbial extract. Complementary computational approaches are utilized to understand the structural basis for the separation of primary metabolism derived linear peptides from secondary metabolite cyclic and modified cyclic species. These findings provide a platform for enhancing the identification of secondary metabolic peptides with distinct mobility-mass ratios within complex biological samples.
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Abstract
A technique where a separation technique is coupled with an online spectroscopic detection technology is known as hyphenated technique, e.g., GC-MS, LC-PDA, LC-MS, LC-FTIR, LC-NMR, LC-NMR-MS, and CE-MS. Recent advances in hyphenated analytical techniques have remarkably widened their applications to the analysis of complex biomaterials, especially natural products. This chapter focuses on the applications of hyphenated techniques to pre-isolation and isolation of natural products, dereplication, online partial identification of compounds, chemotaxonomic studies, chemical finger-printing, quality control of herbal products, and metabolomic studies, and presents specific examples. However, a particular emphasis has been given on the hyphenated techniques that involve an LC as the separation tool.
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187
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McAlpine JB, Friesen JB, Pauli GF. Separation of natural products by countercurrent chromatography. Methods Mol Biol 2012; 864:221-254. [PMID: 22367899 DOI: 10.1007/978-1-61779-624-1_9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Countercurrent Chromatography (CCC) provides the natural product chemist with a high-resolution separatory method, which is uniquely applicable to sensitive (unstable) compounds and which allows virtually quantitative recovery of the load sample. Different instruments use different means of retaining a stationary liquid phase. The solvent system (SS) can be chosen to optimize the separatory power and the number of systems available is limitless. Several examples are provided to illustrate the power of the method and to guide the chemist in choice of an appropriate SS.
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Abstract
Chromatography is a process for the separation of compounds from the mixtures. Gas chromatography (GC) is one of the most important and common techniques in separation science. The main focus of this chapter is to demonstrate a hands-on approach to preparative gas chromatography (Prep-GC) technique and its use for the isolation of natural products, particularly terpenes and other volatiles. Starting from the classification of GC separations, columns, and stationary phases, sampling techniques, mobile phases, detectors, and fraction collector systems of analytical and preparative gas chromatographic separations are comparatively covered in this chapter.
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Abstract
In principle, the isolation of secondary metabolites from microbes does not differ from their isolation from other organisms. The extraction procedure may of course be quite different, especially if it is carried out in an industrial scale, but when an extract containing the metabolites of interest is at hand, it is the same palette of adsorbents and chromatographic techniques that provide the major tools for the fractionation and eventual isolation of the pure compounds. Compared to plants, in which one is sure to find secondary metabolites of certain types, e.g., flavonoids, microbes can be expected to produce virtually anything and it is important to go about the fractionation procedure with an open mind. This chapter presents an overview of preparation of extracts from microbial sources, and various methods and strategies involved in the isolation and characterization of microbial natural products.
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Abstract
Natural products play a vital role in drug discovery. They have served as the basic reference and initiators in drug discovery programs. Natural products as pure compounds have been involved in western medicine as drugs or lead compounds for drug discovery and development. In traditional medicine, they have been involved for a very long time as medicinal extracts, infusions, decoctions, or other therapeutic preparations. Modern drug discovery programs require an arsenal of drug candidate molecules in pure form whose activities (usually against cells or enzymes) are rapidly determined using high-throughput screening (HTS) and activities are expected in micro- (μM) to nanomolar (nM) levels. The difficulty in meeting today's standards for drug candidate molecules poses the question: are natural products still relevant in modern drug discovery programs? This and other issues, including the spectroscopic investigation of crude extracts, are discussed.
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Abstract
Supercritical fluids (SCFs) are increasingly replacing the organic solvents, e.g., n-hexane, chloroform, dichloromethane, or methanol, that are conventionally used in industrial extraction, purification, and recrystallization operations because of regulatory and environmental pressures on hydrocarbon and ozone-depleting emissions. In natural products extraction and isolation, supercritical fluid extraction (SFE), especially employing supercritical CO(2), has become a popular choice. Sophisticated modern technologies allow precise regulation of changes in temperature and pressure, and thus manipulation of solvating property of the SCF, which helps the extraction of natural products of a wide range of polarities. This chapter deals mainly with the application of the SFE technology in the natural products extraction and isolation, and outlines various methodologies with specific examples.
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Yang SC, Chang SS, Chen CYC. Identifying HER2 inhibitors from natural products database. PLoS One 2011; 6:e28793. [PMID: 22174899 PMCID: PMC3236219 DOI: 10.1371/journal.pone.0028793] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 11/15/2011] [Indexed: 01/09/2023] Open
Abstract
The relationship between abnormal HER2 expression and cancer is important in cancer therapeutics. Formation and spread of cancer cells may be restricted by inhibiting HER2. We conducted ligand-based and structure-based studies to assess the potency of natural compounds as potential HER2 inhibitors. Multiple linear regression (MLR) and support vector machine (SVM) models were constructed to predict biological activities of natural compounds, and molecular dynamics (MD) was used to assess their stability with HER2 under a dynamic environment. Predicted bioactivities of the natural compounds ranged from 6.014–9.077 using MLR (r2 = 0.7954) and 5.122–6.950 using SVM (r2 = 0.8620). Both models were in agreement and suggest bioactivity based on candidate structure. Conformation changes caused by MD favored the formation of stabilizing H-bonds. All candidates had higher stability than Lapinatib, which may be due to the number and spatial distribution of additional H-bonds and hydrophobic interactions. Amino acids Lys724 and Lys736 are critical for binding in HER2, and Thr798, Cys805, and Asp808 are also important for increased stability. Candidates may block the entrance to the ATP binding site located within the inner regions and prevent downstream activation of HER2. Our multidirectional approach indicates that the natural compounds have good ligand efficacy in addition to stable binding affinities to HER2, and should be potent candidates of HER2 inhibitors. With regard to drug design, designing HER2 inhibitors with carboxyl or carbonyl groups available for H-bond formation with Lys724 and Lys736, and benzene groups for hydrophobic contact with Cys805 may improve protein-ligand stability.
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Li L, Xiao Y, Yu D, Ma Y, Huang W, Tian G, Chen L. [Determination of three organic acids in Schisandrae Chinensis Fructus by HPLC]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 2011; 36:3286-3289. [PMID: 22393736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
OBJECTIVE To establish an HPLC method for determination of three organic acids in Schisandrae Chinensis Fructus. METHOD The separation was performed on a C18 column with acetonitrile-15 mmol x L(-1) KH2 PO4 (1:99) and methanol-0.5% acetic glacial as the mobile phrase to determine the content of kinic acid, citric acid, and protocatechuic acid. RESULT Three kinds of organic acid can be detective in different samples, and the average content of the three organic acids were about 18%, among which the citric acid was the highest (18%). CONCLUSION Since organic acids is an important parts of the material basis in Schisandrae Chinensis Fructus, it is necessary to carry out the pharmacological research associated with the function of Schisandrae Chinensis Fructus. Further, it will provide scientific basis for the drug relevance research between material basis and efficiency, as well as the foundation for the relevance research on the properties and Five Tastes of traditional Chinese medicine.
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Nielsen KF, Månsson M, Rank C, Frisvad JC, Larsen TO. Dereplication of microbial natural products by LC-DAD-TOFMS. JOURNAL OF NATURAL PRODUCTS 2011; 74:2338-2348. [PMID: 22026385 DOI: 10.1021/np200254t] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Dereplication, the rapid identification of known compounds present in a mixture, is crucial to the fast discovery of novel natural products. Determining the elemental composition of compounds in mixtures and tentatively identifying natural products using MS/MS and UV/vis spectra is becoming easier with advances in analytical equipment and better compound databases. Here we demonstrate the use of LC-UV/vis-MS-based dereplication using data from UV/vis diode array detection and ESI+/ESI- time-of-flight MS for assignment of 719 microbial natural product and mycotoxin reference standards. ESI+ was the most versatile ionization method, detecting 93% of the compounds, although with 12% ionizing poorly. Using ESI+ alone, 56.1% of the compounds could be unambiguously assigned based on characteristic patterns of multiple adduct ions. Using ESI-, 36.4% of the compounds could have their molecular mass assigned unambiguously using multiple adduct ions, while a further 41% of the compounds were detected only as [M - H]-. The most reliable interpretations of conflicting ESI+ and ESI- data on a chromatographic peak were from the ionization polarity with the most intense ionization. Poor ionization was most common with small molecules (<200 Da). In ESI-, these were often polar and basic, while in ESI+ they were small aromatic acids or anthraquinones. No single ion-source settings could be applied over a m/z 60-2000 range. However, continuous switching among three settings (e.g., for 0.5 s each) during the chromatographic run allowed MS of both small labile molecules and large peptides, and pseudo MS/MS data on labile molecules since the settings for large molecules often induce fragmentation into small molecules.
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Kiselev D, Bonacina L, Wolf JP. Individual bioaerosol particle discrimination by multi-photon excited fluorescence. OPTICS EXPRESS 2011; 19:24516-24521. [PMID: 22109478 DOI: 10.1364/oe.19.024516] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Femtosecond laser induced multi-photon excited fluorescence (MPEF) from individual airborne particles is tested for the first time for discriminating bioaerosols. The fluorescence spectra, analysed in 32 channels, exhibit a composite character originating from simultaneous two-photon and three-photon excitation at 790 nm. Simulants of bacteria aggregates (clusters of dyed polystyrene microspheres) and different pollen particles (Ragweed, Pecan, Mulberry) are clearly discriminated by their MPEF spectra. This demonstration experiment opens the way to more sophisticated spectroscopic schemes like pump-probe and coherent control.
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Xu Y, Wu F, Yao Z, Jiang MZAS. Synthesis of quinoxaline 1,4-di-N-oxide analogues and crystal structure of 2-carbomethoxy-3-hydroxyquinoxaline-di-N-oxide. Molecules 2011; 16:6894-901. [PMID: 21841728 PMCID: PMC6290564 DOI: 10.3390/molecules16086894] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/03/2011] [Accepted: 08/08/2011] [Indexed: 11/16/2022] Open
Abstract
A series of quinoxaline 1,4-di-N-oxide analogues were prepared from benzofurazan N-oxide derivatives and β-diketone ester compounds by the improved Beirut reaction. The structures of the target products were characterized by NMR, MS, IR and elemental analysis measurements, and that of 2-carbomethoxy-3-hydroxyquinoxaline- di-N-oxide was further confirmed by single-crystal X-ray diffraction. Its crystal structure belongs to the monoclinic system, space group C2/c with a = 14.4320 (12) Å, b = 10.7514 (9) Å, c = 13.2728 (11) Å, V = 1958.5 (3) Å 3, Z = 8. The X-ray crystallographic analysis reveals that quinoxaline 1,4-di-N-oxide displays acyloin-endiol tautomerism.
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197
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Al-Amiery AA, Musa AY, Kadhum AAH, Mohamad AB. The use of umbelliferone in the synthesis of new heterocyclic compounds. Molecules 2011; 16:6833-43. [PMID: 21832973 PMCID: PMC6264737 DOI: 10.3390/molecules16086833] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 07/22/2011] [Accepted: 08/01/2011] [Indexed: 11/16/2022] Open
Abstract
New coumarin derivatives, namely 7-[(5-amino-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one, 5-[(2-oxo-2H-chromen-7-yloxy)methyl]-1,3,4-thiadiazol-2(3H)-one, 2-[2-(2-oxo-2H-chromen-7-yloxy)acetyl]-N-phenylhydrazinecarbothioamide, 7-[(5-(phenylamino)-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one and 7-[(5-mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methoxy]-2H-chromen-2-one were prepared starting from the natural compound umbelliferone. The newly synthesized compounds were characterized by elemental analysis and spectral studies (IR, ¹H-NMR and ¹³C-NMR).
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Simpson JR, McPherson EG. The tree BVOC index. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2011; 159:2088-93. [PMID: 21435760 DOI: 10.1016/j.envpol.2011.02.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 02/22/2011] [Accepted: 02/24/2011] [Indexed: 05/03/2023]
Abstract
Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes in BVOC emissions are calculated as the result of transitioning to a lower-emitting species mix in future planting. A simplified method for calculating the emissions reduction and a Tree BVOC index based on the calculated reduction is described. An example illustrates the use of the index as a tool for implementation and monitoring of a tree program designed to reduce BVOC emissions as a control measure being developed as part of the State Implementation Plan (SIP) for the Sacramento Federal Nonattainment Area.
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Rossano R, Larocca M, Riccio P. Digestive enzymes of the crustaceans Munida and their application in cheese manufacturing: a review. Mar Drugs 2011; 9:1220-1231. [PMID: 21822412 PMCID: PMC3148499 DOI: 10.3390/md9071220] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/27/2011] [Accepted: 06/29/2011] [Indexed: 11/30/2022] Open
Abstract
Crustaceans Munida (fam. Galatheideae, ord. Decapodi) were fished in the Southern Adriatic Sea and their proteolytic activities were characterized and tested for potential application in cheese manufacturing. Enzymes extracted from whole crustaceans, mainly serine proteases, showed high caseinolytic and moderate clotting activities. Analysis by 2D zymography of the digestive enzymes extracted from Munida hepatopancreas, showed the presence of several isotrypsin- and isochymotrypsin-like enzymes in the range of 20–34 kDa and 4.1–5.8 pI. Moreover, specific enzymatic assays showed the presence of aminopeptidases and carboxypeptidases A and B. Overall, optimum activity was achieved at pH 7.5 and 40–45 °C. Caseinolytic activity, determined both spectrophotometrically and by SDS gel electrophoresis, indicated higher activity on β-casein than on α-casein. Miniature cheddar-type cheeses and Pecorino-type cheeses were manufactured by adding starter, rennet and Munida extracts to milk. Reverse-phase HPLC and MALDI-ToF mass spectrometry showed a more complex pattern of proteolytic products in cheeses made using Munida instead of chymosin. Munida extracts were found to degrade the chymosin-derived β-casein fragment f193–209, one of the peptides associated with bitterness in cheese. In conclusion, Munida digestive enzymes represent a promising tool for development of new cheese products and shorten cheese ripening when used either alone or in addition to calf rennet.
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Bundgaard Jensen T, Pasternak A, Stahl Madsen A, Petersen M, Wengel J. Synthesis and structural characterization of 2'-fluoro-α-L-RNA-modified oligonucleotides. Chembiochem 2011; 12:1904-11. [PMID: 21728225 DOI: 10.1002/cbic.201100161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Indexed: 11/07/2022]
Abstract
We describe the synthesis and binding properties of oligonucleotides that contain one or more 2'-fluoro-α-L-RNA thymine monomer(s). Incorporation of 2'-fluoro-α-L-RNA thymine into oligodeoxynucleotides decreased thermal binding stability slightly upon hybridization with complementary DNA and RNA with the smallest destabilization towards RNA. Thermodynamic data show that the duplex formation with 2'-fluoro-α-L-RNA nucleotides is enthalpically disfavored but entropically favored. 2'-Fluoro-α-L-RNA nucleotides exhibit very good base pairing specificity following Watson--Crick rules. The 2'-fluoro-α-L-RNA monomer was designed as a monocyclic mimic of the bicyclic α-L-LNA, and molecular modeling showed that this indeed is the case as the 2'-fluoro monomer adopts a C3'-endo/C2'-exo sugar pucker. Molecular modeling of modified duplexes show that the 2'-fluoro-α-L-RNA nucleotides partake in Watson--Crick base pairing and nucleobase stacking when incorporated in duplexes while the unnatural α-L-ribo configured geometry of the sugar is absorbed by changes in the sugar-phosphate backbone torsion angles. The duplex behavior of our new nucleotide follows that of α-L-LNA, by and large.
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