Sugar fatty acid esters applications

There has been a resurgence in the study and use of natural surfactants in recent years. The primary reasons are that these surfactants are generally viewed as possessing the potential to have less adverse impact on the environment and to be nontoxic. Sugar fatty acid esters are one group that has been receiving renewed attention for these very reasons. Condensation of one of the reactive sugar hydroxyl functionalities with a fatty acid yields a biosurfactant that has potential application in food, cosmetics, and pharmaceuticals. 

Perhaps the most extensive area of research for sugar fatty acid esters is formulation of microemulsion systems. The potential applicability of these low-toxicity surfactants in the areas of cosmetics and food products has been the principle driving force for this research. 

Garti et al. have studied extensively the growing potential for microemulsions based on sugar fatty acid esters for utility in food products and have published a fairly recent review on the subject [94]. Since that review their work has continued in this important area of application for these materials, with a number of publications in the past 3 years. 

Drummond, C. J., Fong, C., Krodkiewska, I. et al. (2003) Sugar fatty acid esters, in Novel Surfactants Preparation, Applications, and Biodegradability, 2nd edn. Revised and Expanded (ed. K. Holmberg), Surfactant Science Series 114, Chapter 3, Marcel Dekker, New York, pp. 95-128. 

The selective enzyme-catalyzed acylation of carbohydrates is of great interest, as of carbohydrates fatty acid esters of carbohydrates have important applications in detergents, cosmetics, foodstuff, and pharmaceuticals because of their surface-active properties. Monoacylated sugars have been synthesized by lipase-catalyzed transesterifications of activated esters in pyridine and by protease-catalyzed esterifications in DMF. A most remarkable new development... 

One area of rapidly expanding interest is the use of reverse micellar systems of sugar-based surfactants in the extraction of proteins and other sensitive materials. The use of hydrophilic, nonionic, sugar-based surfactants for membrane protein extraction is well known to be effective due to the mild, nondenaturing properties of these surfactants when compared with ionic surfactants or polyoxyethylene derivatives. For the same reasons, protein extraction into reverse micellar systems is now becoming a popular medium for such applications. Alkyl sorbitan esters and ethoxylated sorbitan esters, such as Tween 85 [107] and Span 60 [108], have been used successfully to form reverse micellar systems for protein extraction. Blends of Tween and Span have also been found to be effective for this purpose [109]. More recently, commercially available sucrose fatty acid esters have been shown to form biocompatible reverse micellar systems into which cytochrome c is effectively extracted [110]. 

An early application is the preparation of 6-O-acylglucopyranosides (sugar esters) (Scheme 13.1). CALB was found to chemoselectively esterify the primary 6-OH with fatty acids. Ethyl D-glucopyranoside was initially selected due to improved solubility in neat fatty acid [44], but reactions with unmodified mono- and disaccharides suspended in acetone, tert-butyl alcohol or DMSO-mixtures have also been reported [45], The products have found applications as non-ionic tensides. 

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