Glycolipids of soft wheat flour. I. Isolation and characterization of 1-O-(6-O-acyl-β-D-galactopyranosyl)-2,3-di-O-acyl-D-glyceritols and phytosteryl 6-O-acyl-β-D-glucopyranosides

Abstract

Two groups of glycolipids were isolated from soft wheat flour. The first group, 1-0-(6-0-acyl-B-Dgalactopyranosy1)-2,3-di-0-acyl-D-glyceritols (I), was saponified to yield fatty acids and 1-0-B-Dgalactopyranosyl-D-glyceritol in the molar ratio 3:l. Methylation of 1 followed by saponilkation of the methylated product gave 1-0-(2,3,4-tri-O-methyl-~-~-ga~actosyl)-~-glyceritol which provided 2,3,4-tri-0-methyl-D-galactose and glyceritol upon hydrolysis. In periodate oxidation studies 1 consumed two moles of oxidant and yielded tri-0-acyl dialdehydes (6) without liberating fatty acids. Sodium borohydride reduction of 6 followed by saponification, acid hydrolysis, and another borohydride reduction gave glyceritol and ethylene glycol in the expected manner.The second group of glycolipids, phytosteryl 6-0-acyl-P-D-glucopyranosides, was methylated and the products were saponified to give phytosteryl 2,3,4-tri-0-methyl-a-D-glucopyranosides (12) and fatty acids. Methanolysis of 12 gave principally B-sitosterol, campesterol, and methyl 2,3,4-tri-0-methyl-a-and B-D-glucosides.

Acylated monogalactosyl diacylglycerol: prevalence in the plant kingdom and identification of an enzyme catalyzing galactolipid head group acylation in Arabidopsis thaliana

“…Grains contain substantial amounts of plastid associated galactolipids and any ‘wet’ processing of these without previous heat inactivation is likely to trigger head group acylation of galactolipids which could substantially alter the properties of the product. The occurrence of head group acylated galactolipids has in fact already been described in wheat flour (Myhre, ; Macmurray and Morrison, ).…”

Determination of Polar Lipids in Wheat and Oat by a Complementary Approach of Hydrophilic Interaction Liquid Chromatography and Reversed-Phase High-Performance Liquid Chromatography Hyphenated with High-Resolution Mass Spectrometry

“…The structural derivatives have received little attention in studies to date, which is why little is known about their biological functions. The glycosyldiacylglycerols MGDG and DGDG, which can be classified as glycolipids, account for the majority of membrane lipids in plastids as well as the majority of membrane lipids in amyloplasts. − While the glycosyldiacylglycerols of plastids predominantly carry linolenic acid as a fatty acid, linoleic acid makes up a large proportion of the fatty acids in glycosyldiacylglycerols in amyloplasts. , Furthermore, structural derivatives, such as acyl-MGDG, acylated at the C-6 position are also found in plants. , The acylation of MGDG is thought to be triggered by cell rupture. , However, homogenization of plant leaves and thawing of the plant after snap freezing also lead to an increase in acyl-MGDG. , In their study, Vu et al showed that the acyl-galactose unit of the formed acyl-MGDG species in different plant species deviated after the same stress treatment, but also the type of stress treatment influenced the formation of the diverse acyl-MGDG species . Heinz et al proposed three separate formation pathways based on the quantitative determination of glycosyl diacylglycerols and glycosyl monoacylglycerols as a result of incubation experiments.…”

Head-Group Acylation of Chloroplast Membrane Lipids

“…In 1967, Heinz reported the discovery of a glycolipid more hydrophobic than MGDG, with a 1:1:3 molar ratio of glycerol, galactose, and fatty acids in spinach leaf homogenates [ 11 ]. Soon a similar lipid was discovered in wheat flour [ 12 ]. The lipid from both sources was shown to be MGDG with a third acyl group esterified to the carbon at the 6-position of the galactose [ 12 , 13 ] ( Figure 1 a).…”

“…Soon a similar lipid was discovered in wheat flour [ 12 ]. The lipid from both sources was shown to be MGDG with a third acyl group esterified to the carbon at the 6-position of the galactose [ 12 , 13 ] ( Figure 1 a).…”

“…While extra-plastidic head-group acylated polar lipids, such as N-acyl phosphatidylethanolamine, also have been identified in plants (as well as in animals), the focus of this review is the head-group acylated lipid classes of the plant chloroplast. 12,15 ) and (c) acylated phosphatidylglycerol (acPG), i.e., 1-,2,di-O-acyl-sn-glycero-3-phospho-(3-acyl)-1-glycerol (sn1 = 18:3 ∆9, 12,15 , sn2 = 16:1 ∆3trans , 3′ = 18:3 ∆9, 12,15 ).…”