Synthesis and Characterization of Dioctanoyl Glycerate as Water-soluble Trypsin Inhibitor.

Glyceric acids (GAs) esterified with long acyl chains (> C16) exhibit antitrypsin activity (Folia Microbiol. 46, 21-23 (2001)). However, their hydrophobic nature, derived from the long acyl chains, has limited the number of studies on their physical and biological properties. To improve the water solubility of diacyl GAs, GA was esterified with octanoyl groups (C8), and its physical properties were investigated. Synthesized dioctanoyl GA was not water-soluble, whereas its sodium salt was. Surface tension measurements of dioctanoyl GA sodium salt (diC8GA-Na) in water revealed that the critical micelle concentration (CMC) was 0.82 mM, and surface tension at the CMC was 25.5 mN/m. Additionally, diC8GA-Na inhibited casein digestion by trypsin to a greater extent than dioleoyl GA. These data suggest that water-soluble diacyl GAs may have utility as surfactants and bioactive compounds.