Isolation and characterization of novel naturally occurring sophorolipid glycerides

Abstract

Sophorolipids are promising glycolipid biosurfactants as they are readily produced and functional. Lactonic and acidic sophorolipids are well-known. Here, we used chromatography and suitable solvent systems to find and characterize novel, naturally occurring sophorolipid-glyceride derivatives from a Starmerella bombicola product. The sophorolipid-tri-glyceride and -di-glyceride are highly water soluble; they are more bulky and have a higher molecular weight than typical sophorolipids. Furthermore, the surface tension of the purified tri- and di-glyceride aqueous solutions decreases to approximately 40 mN/m, similar to that of conventional acidic sophorolipids. The tri-glyceride of the two sophorolipids and a fatty acid is more lipophilic, with oily properties and little surface activity. These sophorolipid-glycerides are the third-most abundant component after the well-known sophorolipids in S. bombicola products (the lactone:acid:glyceride component ratio in our samples was 49.2:33.5:17.3), and synergistic effects are expected when these sophorolipids are mixed.