Of glycosidic compounds

In general, SPE provides high recoveries of most fermentative volatiles in wine (80-100%), but requires longer times and is quite solvent consuming. On the other hand, the main advantage of this approach is to allow separation of the fraction of glycoside compounds that can be analyzed as aglycones after an enzymatic hydrolysis. 

The methanolic extract is applied in a comer on a 10 x 10 cm commercial glass plate and developed over 9 cm in the system described for the separation of glycosidic compounds. After development, the plate is thoroughly dried and placed in a desiccator containing a beaker with 25% HCI. The air outlet must be open, and a tube is used to lead acid fumes into a beaker containing 10% aqueous sodium hydroxide. The apparatus is placed in an oven and the hydrolysis is completed after heating for 35 min at 90°C. The plate is carefully removed and dried in a nitrogen stream. Second-direction development is performed with petroleum ether (40-60 Q-ethyl acetate-formic acid (75 25 1) as the mobile phase. 

The amidmes (98) have been thesized firom nojirunycin (97) as shown in Scheme 23, and isolated as their stable hydrochloride salts. These amidines are analogues of the presumed oxonium ion intermediates in enzymic t drolysis of glycosides compound (98 R s H) was found to be a potent competitive inhibitor of sweet almond -glucosidase and mannose- and galactose-processing enzymes. ... 

Pvranoid Compounds.- A review has appeared on anomeric free radicals which encompasses the synthesis of -glycosidic compounds. ... 

Identification, isolation, and removal of (polyhydroxy)benzenes from the environment have received increased attention throughout the 1980s and 1990s. The biochemical activity of the benzenepolyols is at least in part based on thek oxidation—reduction potential. Many biochemical studies of these compounds have been made, eg, of enzymic glycoside formation, enzymic hydroxylation and oxidation, biological interactions with biochemically important compounds such as the catecholamines, and humic acid formation. The range of biochemical function of these compounds and thek derivatives is not yet fully understood. 

Glycosides, particularly of phenoHc compounds, are widely distributed in plant tissues (2,10). Glycosides of anthocyanidins, flavones, flavanols, flavanones, flavanonols, stilbenes and saponins, gaUic acid derivatives, and condensed tannins are all common. 

The present work involves the study of methyl glycosides and O-isopropylidene ketals of various isomeric deoxy sugars by mass spectrometry. Several of the compounds selected for the present study have free hydroxyl groups, and interpretation of their mass spectra shows the scope of the study of these and related deoxy sugar derivatives by mass spectrometry without prior substitution of all hydroxyl groups. Some of the candidates (compounds 4, 7, 8 and 10) are structurally related to biologically-derived deoxy sugars. 

The widespread occurrence and biological significance of polyoxygenated carbocycles provided the impetus to apply RCM to sugar-derived dienes. Carbohydrate carbocyclization based on a sequence of Vasella reductive opening of iodo-substituted methyl glycosides [25], and RCM of the dienes available from the resulting unsaturated aldehydes, were used to prepare a series of natural compounds (Schemes 5-7). 

Sweetness is a quality that defies definition, but whose complexity can be appreciated merely by examining the molecular structures of those compounds that elicit the sensation. They come in all molecular shapes and sizes, and they belong to such seemingly unrelated classes of compounds as aliphatic and aromatic organic compounds, amino acids, peptides and proteins, carbohydrates, complex glycosides, and even certain inorganic salts. 

Bitter taste, like sweet taste, is exhibited by a very diverse group of chemical compounds. Because the bitter taste is generally regarded as unpleasant, and because it is often associated with such compounds as those alkaloids and glycosides that are harmful to man, detailed studies have been minimal. There is thus very little information available from which to deduce the chemical grouping common to those compounds eliciting the bitter response. 

Knowledge of the identity of phenolic compounds in food facilitates the analysis and discussion of potential antioxidant effects. Thus studies of phenolic compounds as antioxidants in food should usually by accompanied by the identification and quantification of the phenols. Reversed-phase HPLC combined with UV-VIS or electrochemical detection is the most common method for quantification of individual flavonoids and phenolic acids in foods (Merken and Beecher, 2000 Mattila and Kumpulainen, 2002), whereas HPLC combined with mass spectrometry has been used for identification of phenolic compounds (Justesen et al, 1998). Normal-phase HPLC combined with mass spectrometry has been used to identify monomeric and dimeric proanthocyanidins (Lazarus et al, 1999). Flavonoids are usually quantified as aglycones by HPLC, and samples containing flavonoid glycosides are therefore hydrolysed before analysis (Nuutila et al, 2002). 

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