Natural product analysis, nuclear

Yang Z. Online hyphenated liquid chromatography-nuclear magnetic resonance spectroscopy-mass spectrometry for drug metabolite and nature product analysis. J Pharm Biomed Anal 2006 40 516-527. 

Natural products—Analysis. 2. Nuclear magnetic resonance spectroscopy. I. Rahman. Atta-ur-, 1942- II. Ahmad, Viqar Uddin. III. Title Carbon-thirteen NMR of natural products. 

Gossi, A., Uta, S., and Gotz, S. 2012, Thin-layer chromatography-nuclear magnetic resonance spectroscopy—A versatile tool for pharmaceutical and natural products analysis, CHIMIA, 66 347-349. 

Within the past two decades, the importance of nuclear magnetic resonance (n.m.r.) spectroscopy has enlarged tremendously. Its advantages over other methods in the structural and conformational analysis of such complex molecules as natural products, and particularly with regard to the still-increasing importance of medical investigations using n.m.r. techniques, is abundantly evident. Because destruction of the sample is avoided, different n.m.r. experiments can be performed repeatedly, and... 

Use of an integrated system incorporating CCC separation, PDA detector, and LC-MS proved to be a valuable tool in the rapid identification of known compounds from microbial extracts.6 This collection of analytical data has enabled us to make exploratory use of advanced data analysis methods to enhance the identification process. For example, from the UV absorbance maxima and molecular weight for the active compound(s) present in a fraction, a list of potential structural matches from a natural products database (e.g., Berdy Bioactive Natural Products Database, Dictionary of Natural Products by Chapman and Hall, etc.) can be generated. Subsequently, the identity of metabolite(s) was ascertained by acquiring a proton nuclear magnetic resonance ( H-NMR) spectrum. 

From a medicinal chemist s perspective, nuclear magnetic resonance (NMR) was still the analytical tool of choice, whereas mass spectrometry, infrared (IR), and elemental analyses completed the necessary ensemble of analytical structure confirmation. Synthesis routines were capable of generating several milligrams of product, which is more than adequate for proton and carbon NMR experiments. For analyses that involved natural products, metabolites, or synthetic impurities, time-consuming and often painstaking isolation methods were necessary, followed by expensive scale-up procedures, to obtain the necessary amount of material for an NMR experiment. In situations that involved trace-mixture analysis, radiolabeling approaches were often used in conjunction with various formats of chromatographic separation. 

In 2002, through the use of nuclear magnetic resonance (NMR) and mass spectrometry/mass spectrometry (MS/MS) analysis, the planar and partial stereostructure of a SAAF from the egg-conditioning medium of C. intestinalis w s elucidated to be a previously uncharacterized sulfated steroid 3,4,7,26-tetrahydroxycholestane-3,26-disulfate (30).73 Its structure was deduced from only 4p.g (6 nmol) of sample. Thus, SAAF may represent the smallest amount of sample used in the structure elucidation of novel nonpeptidic or nonoligosaccharide natural products.74... 

In general, any analytical equipment or procedure used in the field of natural products chemistry and environmental engineering is also helpful in aroma analysis 64,65 The history and principles of such art are described in detail elsewhere and will not be featured here. Gas chromatography (GC), GC-mass spectrometry (MS), and nuclear magnetic resonance (NMR) are the most frequently used techniques along with rather specialized setups such as proton transfer reaction-mass spectrometry66 (PTR-MS) used in retronasal aroma analysis (see Chapters 9.02, 9.06, 9.10-9.11). 

Subsequently, shallow water collections of Lyngbya majuscula from Puerto Rico and the Dry Tortugas yielded additional supplies of ATX as well as a new congener termed antillatoxin B (Figure 6.10) [149]. The structure of the new metabolite was determined largely by comparison with the spectroscopic data set for ATX, and stereochemistry deduced by Marfey s analysis for L-alanine while the i-N-methyl homophenylalanine was proposed based on nuclear Overhauser effect (nOe) and bioassay results. Substitution of i-N-methyl homo-phenylalanine, an intriguing amino acid of quite rare occurrence in natural products, for i-N-methyl valine... 

Miraziridine A 7 is a pentapeptide natural product isolated from the marine sponge Theonella aff. mirabilis in Japan in 2000 [3], It was also isolated 12 years later from the red sea sponge Theonella swinhoei [4], Miraziridine A inhibits cathepsin B with an IC50 value of 1.4 pg/ml. The sequencing of the amino acid residues and the absolute stereochemistry of each residue were achieved by a combination of Marfey analysis and nuclear magnetic resonance (NMR) data and resulted in the following sequence (2/ ,3J )-aziridine-2,3-dicarboxylic acid (Azd) (CO)/L-leucine (Leu) (NH), Leu (CO)/(35,45)-statine (Sta) (NH), Sta (CO)/(5)-a-aminobutyric acid... 

Analytical Methods. Identification of Terpenols in Essential Oils by Trifluoroacetylation and F N.m.r. Spectroscopy . Chemical Study of Trifluoroacetyl Signal in the F N.m.r. Spectra of Trifluoroacetylated Natural Products . Structure Determination of Trifluoroacetyl Steroids by F N.m.r. ." Determination of Structure and Quantitative Analyses of Hydroxy Steroids in the Microgram Range. Analysis of Hydroxy Steroids by F N.m.r. Spectroscopy . Nuclear Magnetic Resonance Studies of the Interaction of... 

Life cycle assessment of SOFC technology is still uncommon due to the relatively early stage in technical development. However, several studies have been performed since the end of the 1990s. Since there is a lack of standard commercial equipment that could serve as a basis and reference point for analysis, LCA studies mostly refer to hypothetical concepts and/or extrapolate from laboratory and early market prototypes to commercial units. While the first studies had only little access to operation data at aU (for the fuel cell system itself but also for production processes), the main effort was set in the assessment of inventory data using assumptions, simplifications, and correlations [79, 80]. The main outcomes of these studies were the identification of weak points and the setting of benchmarks for further development. With more information about fuel cells available today and a simultaneous advancement in LCA methodology, the studies became more reliable and detailed, regarding system description [81] as well as the assessment of environmental impacts coimected with inputs and outputs [82]. Especially the extensive data of these two studies found their way to commercial databases for LCA [83] and thereby became available to LCA practitioners. In 2005, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)... 

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