Glycoside structural elucidation

Goto, T., Takase, S., and Kondo, T., PMR spectra of natural acylated anthocyanins determination of stereostructure of awobanin, shisonin and violanin (Commelina communis, Viola tricolor, Perilla orimoides). Tetrahedron Lett, 27, 2413, 1978. Agrawal, P.K., NMR spectroscopy in the structural elucidation of ohgosaccharides and glycosides, Phytochemistry, 31, 3307, 1992. 

The main approaches for the structure elucidation of the resin glycosides involve the use of degradative chemical reactions or the application of high-resolution spectroscopic and spectrometric techniques and combining both has proven to be the best way for total characterization of these complex molecules. 

Complete structure elucidation of individual resin glycoside constituents is now achieved readily by the use of a combination of high-resolution mass spectrometry and NMR spectroscopy. These methods are applicable to the isolated natural products or to their peracetylated and methylated derivatives. 

Noda N, Ono M, Miyahara K, Kawasaki T, Okabe M (1987) Resin Glycosides. I. Isolation and Structure Elucidation of Orizabin-I, II, III and IV, Genuine Resin Glycosides from the Root of Ipomoea orizabensis. Tetrahedron 43 3889... 

The application of MS in structural elucidations of flavonoids has increased dramatically with recent developments related to soft ionization techniques, mass analyzers, and coupled MS techniques (see Sections 2.3.1 and 2.3.2). Based on relatively small flavonoid quantities, reports have provided the molecular mass in addition to structural information about the flavonoid aglycone attachment points of glycosidic res-... 

Brunner, G. et al., A novel acylated flavonol glycoside isolated from Brunfelsia grandiflora ssp. Grandiflora. Structure elucidation by gradient accelerated NMR spectroscopy at 14T, Phytochem. Anal., 11, 29, 2000. 

Materska, M. et al.. Isolation and structure elucidation of flavonoid and phenolic acid glycosides from pericarp of hot pepper fruit Capsicum annum L., Phytochemistry, 63, 893, 2003. 

Besides the structural elucidation of glycosides, research is focused on the application of glycosidases to liberate the aroma-active aglycons from their bound forms. The development of a continuous process of enzymatic treatment (simultaneous enzyme catalysis extraction) [50] opened the doors for the industrial large-scale production of aroma compounds from their non-volatile conjugates. 

Osterdahl, B.-G. Chemical Studies on Bryophytes. 19th Application of l3C NMR. In. Structural Elucidation of Flavonoid C-Glycosides from Hedwigia ciliata1, Acta Chemica Scandinavica B32, 1978, pp. 93-97 (occurrence, I3C-NMR)... 

The structures of the compounds were elucidated by a combination of NMR techniques (lH-, 13C-, and 13C-DEPT NMR) and chemical transformation, enzymatic degradation, and as well as mass spectrometry, which gives information on the saccharide sequence. A more recent approach consists of an extensive use of high-resolution 2D NMR techniques, such as homonuclear and heteronuclear correlated spectroscopy (DQF-COSY, HOHAHA, HSQC, HMBC) and NOE spectroscopy (NOESY, ROESY), which now play the most important role in the structural elucidation of intact glycosides. These techniques are very sensitive and non destructive and allow easy recovery of the intact compounds for subsequent biological testing. 

Studies of other Polygonum species are under way to establish the presence of homologs of the vanicosides. Isolation and structure elucidation of these homologs, along with the preparation of derivatives by synthetic methodology, will facilitate the establishment of a library of compounds which will be screened for PKC inhibitory activity. The results will produce a better understanding of the structure-activity relationships inherent in this class of phenylpropanoid glycosides. 

As a complete structural elucidation of complex glycosidic compounds cannot be achieved by one-dimensional H-NMR spectra, which are provided by on-flow LC-NMR (13C-NMR data are still required for an unambiguous assignment of resonances), two approaches have proven to be effective in the case of asterosaponins in order to identify new compounds for a subsequent semi-preparative isolation ... 

R. Vleggaar, F. R. van Heerden, and L. A. P. Anderson, Toxic constituents of the Asckpiadaceae. Structure elucidation of Sarcovimiside A-C, pregnane glycosides of Sarcostemma viminale, J. Chem. Soc. Perkin Trans. I (1983) 483 187. 

J. Thiem, J. Schwentner, E. Schuttpelz, and J. Kopf, Synthesis, structure elucidation and conformational studies of 1 - 4-linked disaccharide glycosides, Chem. Ber., 112 (1979) 1023-1034. 

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