Glycoside esters

Hydrolases such as the digestive enzymes amylase and lactase catalyse hydrolysis of glycosides, esters, anhydrides and amides. 

Yokoyama, A., G. Sandmann, T. Hoshino, K. Adachi, M. Sakai, and Y. Shizuri. 1995. Thermozeaxanthins, new carotenoid-glycoside-esters from thermophilic eubacterium Thermus thermophilus. Tetrahedron Lett. 36 4901 1904. 

Pro-drugs are conjugates of drugs with carrier molecules mostly of inert nature. The microbial enzymes in the colon are responsible for the cleavage of the drug-carrier bond. A variety of pro-drugs have been synthesized, mainly azo compounds, glycosides, esters and amides [24]. 

Gudej, J. and Nazaruk, J., Apigenin glycoside esters from flowers of Beilis perennis L., Acta Pol. Pharm., 54, 233, 1997. 

I, 2-rrani-linked glycosides and glycosidic esters, Tetrahedron Lett. 37 1331 (1990). 

G. H. Veeneman, S. H. van Leeuwen, and J. H. van Boom, lodonium ion promoter reactions at the anomeric centre. II. An efficient thioglycoside mediated approach toward the formation of 1,2-irons linked glycosides and glycosidic esters, Tetrahedron Lett. 3/ 1331 (1990). 

Nature provides us with many glycoside esters in which the acyl group is attached to the sugar portion an example is the compound vacciniin already mentioned. However, the largest group of natural acyl derivatives of sugars is to be found in the gallotannins and related substances. 

Hydrolysis occurs at all glycosidic, ester, and amide linkages. The products are as follows ... 

Polysaccharides are differentially stable to cold dilute alkali, which facilitates classification as alkali-stable and alkali-sensitive (Reeves and Blouin, 1957). High concentrations of alkali swell fibrils, shift conformation, and depolymerize the primary structure. The 1,4-(3 bonds are more alkali-resistant than the 1,4-a bonds. Nonreducing glycosides are more stable than reducing glycosides. Ester and sulfate groups are easily hydrolyzed. 

It is clear that an accurate prediction of the CP, PP, or CFPP is almost impossible, certainly since presence of crystallizable minor components can have a significant effect. Some of these components, such as phytosterol glycoside esters in soy-based FAME, can speed nucleation and crystallization other molecules creating steric hindrance in the growing nucleus will retard crystallization. Such components are often added to biodiesel to reduce the size of crystals or inhibit crystal formation by preventing nucleation. 

Among the water-soluble bases of Aspidosperma polyneuron there has been isolated an ester which after methanolysis yielded the known compound 3-carbomethoxyharman (CCCXXXIX) which was recognized by its NMR- and mass spectra (180, 181, Tables IV and V). The natural alkaloid is presumably a glycosidic ester of the corresponding acid. 

C-Glycosidic esters are not the only functional groups accessible by Wittig and related methodologies. As shown in Scheme 2.8.8, Barnes, ef a/.,129 effected... 

Deoxy-3-0-methyl-D- (or l)-glucose [d- (or l)-thevetose] Pachycarpus lineolatus Asdepias glaucophyUa ester glycosides ester glycosides 190 156... 

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