Glycosides, enzymatic hydrolysis

The cyanogenic glycosides, phaseolunatin [554-35-8], C qH yNO, and vicianin [155-57-7], C2C)H25N02q, have been isolated from lima beans and vetch, respectively. Several studies have reported that heating (cooking) acts to decrease the quantity of HCN Hberated by these compounds upon enzymatic hydrolysis. 

The solubility of iridoids depends on their state (free, glycosylated, acetylated), but usually they are extracted with polar solvents methanol, ethanol, aqueous alcohols, and rarely acetone. Iridoid glycosides are more or less stable some of them are very sensitive to acids and alkalis. Some iridoid glycosides such as aucubin suffer color modification after chemical or enzymatic hydrolysis they give first a blue to green... 

Rubia tinctorum roots Alizarin, munjistin, purpurin, pseudopurpurin, lucidin, nordamnacanthal (as glycosides or aglycones) MeOH/H20, TFA, HCI, H20 (enzymatic hydrolysis) ACN/AcONH4 254 nm/ESI (+) Hydrolysis optimization, characterization of root components... 

G.C.H. Derksen, M. Naayer, T.A. van Beek, A. Capelle, I.K. Haaksman, H.A. van Doren and JE. Groot, Chemical and enzymatic hydrolysis of anthraquinone glycosides from madder roots, Phytochem. Anal., 14, 137 144 (2003). 

Identification of flavonoids Quantification of individual flavonoids depends heavily on the availability of standard references. Only a limited number of common flavonoids are commercially available as standards. Standard references for flavonoid glycosides are particularly difficult to find thus direct quantification of the native glycosides is nearly impossible. Analysis of the aglycones after acid or enzymatic hydrolysis is therefore common practice. When standard flavonoids are not available, or when unknown compounds are encountered in a particular fruit or vegetable, use of a DAD... 

Porphyrin S-glycosidcs can be considered to be good mimics of the O-glycoside derivatives with enhanced stability toward enzymatic hydrolysis.80... 

This type of reaction was used by Langenbeck24 to describe the mechanism underlying the enzymatic hydrolysis of a glycoside (Fig. 4). This... 

To detect the fate of liposomes, the nonfluorescent 4-methylumbelliferyl-p-D-glycoside [4MU-(3-D-glc)] can be encapsulated. 4MU-(3-o-glc) is a substrate for lysosomal 3-d-glycosidase that shows fluorescence after enzymatic hydrolysis to methylumbelliferone (125). 

This important concept was rapidly absorbed by the research community, providing fine-tuning of both glycosidase categorization and inhibitor design. In particular, subtle differences of xylosidase and xylanase specificities were probed, and they provided useful insights into the complex and finely tuned enzymatic hydrolysis of glycosides. 

The structures of oligosaccharides and polysaccharides are usually determined by a combination of methods specific enzymatic hydrolysis to determine stereochemistry and produce smaller fragments for further analysis methylation analysis to locate glycosidic bonds and stepwise degradation to determine sequence and configuration of anomeric carbons. 

Although some forms are detected when tomatine is extracted from the plant, these glycosides are probably either products of enzymatic hydrolysis during extraction or natural intermediates in the biosynthesis and/or degradation of tomatine. 

Black mustard is a light olive-brown powder obtained by grinding the dried ripe seeds of several varieties of plants of the Brassica genus moisture yields from this, through enzymatic hydrolysis of a contained glycoside, are about 0.6% of the volatile oil of mustard, which has as its main ingredient the irritant compound allyl isothiocyanate. Mustard is available in bulk and as the official plaster, the latter used only for the local irritant (counterirritant) properties it develops when applied to the skin after moistening with tepid water. 

IV. Mechanisms for the Enzymatic Hydrolysis ofthe Glycosidic Bond... 

The prevention of further deterioration requires arresting the chain scission reaction caused by acid or enzymatic hydrolysis of the glycosidic linkages. The reduction in DP through chain scission has a dual character to its negative effect upon properties. In addition to the inherent reduction in the tensile properties of the fibers, the lower DP enhances the opportunity for crystallization with resulting embrittlement. 

The sole Nano-probe paper published in 2004 of which the author is aware was the study by Claeyssens and co-workers220 of the enzymatic hydrolysis products of Nothogenia erinacea seaweed xylan, which is a linear homopolymer with mixed / — (1 —3)// — (1 —4) linkages. The sequence of the residues was determined from a combination of nuclear overhauser effect spectroscopy (NOESY) correlations between the anomeric protons and a proton of the residue to which it is glycosidically linked and gHMBC data, that were acquired using Nano-probe capabilities. Finally, in early 2005, Bradley et al.221 compared the ability of cryogenic, Nano- and conventional NMR probes to acquire diffusion-ordered spectroscopy (DOSY) spectra of dilute mixtures of compounds. 

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