The identification of mono-, di-, tri-, and tetragalactosyl-diacylglycerols and their natural estolides in oat kernels.
Oat kernels were extracted with methanol, and glycolipid-enriched fractions were prepared using silica solid phase extraction. Using direct infusion electrospray ionization (ESI) tandem mass spectrometry (MS), high performance liquid chromatography (HPLC)-ESI-MS, and HPLC-atmospheric pressure chemical ionization (APCI)-MS, we confirmed previous reports that digalactosyldiacylglycerol (DGDG) was the most abundant glycolipid in oat kernels and confirmed a previous report of the presence of a DGDG mono-estolide in oat kernels. In the current study we also identified several additional natural galactolipid estolides: two new DGDG estolides (di- and tri-estolides), two trigalactosyldiacylglycerol (TriGDG) estolides (mono- and di-estolides), and one tetragalactosyldiacylglycerol (TetraGDG) estolide (mono-estolide). The levels of total galactolipid estolides in oat kernels were estimated to be about 29% of the total glycolipid fraction. To our knowledge, this report is the first evidence of natural di- and tri-estolides of polar lipids.
Moreau
Robert A
RA
US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA 19038, USA. Robert.Moreau@ars.usda.gov
Doehlert
Douglas C
DC
Welti
Ruth
R
Isaac
Giorgis
G
Roth
Mary
M
Tamura
Pamela
P
Nuñez
Alberto
A
D001274:Atmospheric Pressure; D018554:Avena / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004075:Diglycerides / Q000032:analysis* / Q000737:chemistry / Q000145:classification; D021241:Spectrometry, Mass, Electrospray Ionization
D004075:Diglycerides