Rapid identification of triacylglycerol-estolides in plant and fungal oils

► Presence of TAG-estolides in plant and fungal oils was demonstrated using non-destructive 1H MAS-NMR and intact seeds or fungal material. ► Presence of TAG-estolides in oils was demonstrated using MALDI-TOF MS with a THAP matrix made up in sodium chloride-saturated solvent. ► TAG-estolide structure was determined using MALDI-TOF MS/MS and diagnostic ions are described. Triacylglycerol-estolides are components of the storage oil of certain plant and fungal species and are generally associated with the presence of fatty acids containing hydroxyl groups. These unusual acyl-glycerols can easily go undetected when oils are analyzed by gas chromatography of fatty acid methyl esters, or by thin layer chromatography if the TAG-estolides and TAG have similar polarity. We describe the detection of TAG-estolides in intact seeds of Lesquerella lyrata and whole sclerotia of the ergot fungus Claviceps purpurea using 1H MAS-NMR for nondestructive analysis. We also conducted analysis of small amounts of oil by MALDI-TOF MS to clearly show the presence of TAG-estolides and to rapidly characterize their acyl composition. The matrix used in this work was 2,4,6-trihydroxyacetophenone (THAP) made up in sodium chloride-saturated solvent. We were able to confirm the presence of TAG-estolides with no free hydroxyl groups in the fungal oil, and TAG-estolides with free hydroxyl groups in the oil of L. lyrata. The development of a technique for the rapid identification of TAG-estolides in oil samples will simplify the detection of these novel lipids in plant and fungal species.