The synthesis of certain fatty acid ester derivatives of trehalose and an investigation of their emulsifying properties and bioactivities

Bio-based surfactants exerting both functional and nutritional properties are needed in the food industry. This study reports the one-pot synthesis, using a Novozym 435-catalyzed trans-esterification protocol, of a new family of such compounds, namely a homologous series of 6-O-acylated trehalose and 6,6 '-di-O-acylated trehalose derivatives incorporating long-chain fatty acid residues (12-22 carbons). These mono-and di-esters exhibited HLB values within the 8.3 to 14.7 range and their performance as surface-active compounds, penetration enhancers and anti-cancer agents have been evaluated. They were found to be excellent emulsifiers, maintaining oil-in water emulsions with 566-742 nm mean oil-particle sizes and with the stability of these only gradually deteriorating over a 15-day storage period and during in vitro digestion. Mono-esters 2-4 embodying shorter side chains (12-16 carbons) proved to be excellent foaming agents while congeners 4-6 incorporating longer side chains (16-20 carbons) served as penetration enhancers capable of reversibly opening tight junctions in Caco2 cell mono-layers. Mono-esters 5-7, as well as di-esters 11-13, exerted weak cytotoxic effects on seven human cancer cell lines. This work should serve as a useful guide for the development of the multi-functional properties of such trehalose esters in the food and related industries.