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Polar Lipids from Oat Kernels

¹USDA-ARS Wheat Quality Laboratory, Harris Hall, North Dakota State University, Dept 7640, P.O. Box 6050, Fargo, ND. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.²Corresponding author. E-mail: douglas.doehlert@ndsu.edu³USDA-ARS, Eastern Regional Research Center, Wyndmoor, PA.⁴Kansas Lipidomics Research Center, Division of Biology, Kansas State University, Manhattan, KS.⁵Department of Plant Sciences, North Dakota State University, Dept 7670, P.O. Box 6050, Fargo, ND.

Oat (Avena sativa L.) kernels appear to contain much higher polar lipid concentrations than other plant tissues. We have extracted, identified, and quantified polar lipids from 18 oat genotypes grown in replicated plots in three environments to determine genotypic or environmental variation in these lipids. Validation experiments indicated a solid phase silica gel extraction step elution provided excellent and clean separation of extracted lipids into neutral lipid, glycolipid, and phospholipid fractions. Analysis of phospholipids by HPLC (normal phase, diol column) indicated phosphatidylethanolamine, phosphatidylcholine, phosphatidic acid, phosphatidylglycerol, phosphatidylinositol, and lyso- forms but very little genotypic or environmental variation. Di, tri and tetragalactosyl-diacylglycerols were quantified in the glycolipids, along with their mono-, di-, and triacyl estolides. Most of these exhibited significant genotypic variation. Molecular species analysis of the glycolipids in the Morton cultivar by direct infusion electrospray ionization tandem mass spectrometry confirmed the enormous diversity of galactosyl-lipids in oats. Analyses indicated total lipid of ≈8.3% (dry weight basis), of which ≈10% was phospholipid and 11% was glycolipids. These results indicate that oats are a rich source of polar lipids and contain an extremely rich diversity of galactosyl-lipids.