Effect of Variations in the Fatty Acid Residue of Lactose Monoesters on Their Emulsifying Properties and Biological Activities

Abstract

Lactose fatty acid esters are high-value-added derivatives of lactose and represent a class of biodegradable, nonionic, low-molecular-weight surfactants (emulsifiers) that have considerable potential in the food, cosmetic, and pharmaceutical industries. Certain lactose esters have also garnered attention for their biological activities. In this work, we detail syntheses of a homologous series of 6′-O-acyllactose esters of varying alkyl chain length (from 6 to 18 carbons) and report on their activities as surfactants as well as their antimicrobial and cytotoxic properties. The structure−property profiles established in this work revealed that while the medium-chain esters displayed excellent emulsifying properties and moderate antimicrobial activities, their longer chain congeners exhibited the highest cytotoxicities. As such, we have established that certain 6′-O-acyllactose esters are superior to their sucrose-derived and commercially exploited counterparts. These results will serve as a useful guide for the development of lactose esters as, inter alia, emulsifiers in the food industry.

Fatty acid ester surfactants derived from raffinose: Synthesis, characterization and structure-property profiles

“…We have found that such raffinose esters embodying appropriately hydrophobic acyl side-chains display distinctive and excellent surfactant effects, especially in oil-in-water emulsions. Previously, we have shown that certain disaccharide (lactose, maltose)-derived esters exhibit emulsifying properties superior to those of their commerciallydeployed and sucrose-based counterparts [4,8]. Similar to such earlier observations [4,8,25], we have now found that the performance of raffinose monoesters as surfactants is largely determined by the length of the associated acyl chain.…”

“…It is one of the standard means for classifying surfactants, with a high HLB value being above 11 and a low one being below 9 [26]. Usually, HLBs are predicted by assigning values, as described by Griffin [27], to the given structure or by experimental measurement using, for example, the water number method [8]. Since raffinose is a trisaccharide containing a sucrose substructure, the higher hydrophilicity of raffinose (relative to sucrose) would be expected to result in higher HLB values for the corresponding esters.…”

“…Since sugar esters are converted in vivo, by pancreatic lipase, into their constituent sugar and fatty acid building blocks they are regarded as readily biodegradable, non-toxic and non-irritating surfactants [5]. In addition, many such sugar esters display a variety of attractive biological activities including antimicrobial [6][7][8], antitumor [9], permeability-enhancing [1,10] and other ones [11,12]. Sugar esters currently produced at commercial scale include those derived from sucrose and sorbitan (span).…”

Synthesis and Evaluation of Saccharide-Based Aliphatic and Aromatic Esters as Antimicrobial and Antibiofilm Agents

“…Finally, although some of the sugar-based esters here presented have already been published for other applications and also as possible antibacterial agents [22][23][24][29][30][31][32][33], a detailed comparative study concerning the properties of a relative large number of both aliphatic and aromatic amphiphilic carbohydrate esters as antimicrobial (Gram-positive, Gram-negative, and fungi) and mostly antibiofilm agents is still lacking.…”

“…In these few cases, chemical esterification could be the main road to explore. Among all sugar-based surfactants, sucrose and glucose esters are the most studied and applied derivatives [21][22][23][24], while other derivatives, such as lactose esters, which can be easily obtained from waste whey, and mannose esters, have received less attention.…”