Pakistan Research Repository


Rahman, Salma (2000) LIPID STUDIES OF HORDEUM VULGARE OF THE FAMILY GRAMINEA. PhD thesis, University of the Punjab, Lahore.



Lipid studies of two varieties of Hordeum vulgare (Barley), viz, Jao 87 and Jao 83 have been carried out, with a view to investigate the classes and sub-classes of lipids present in them and to determine the structure of some of the constituent classes. For this purpose the above mentioned varieties of barley were procured from Agriculture Research Institute Faisalabad. The dried grains were crushed and the oil was extracted from the crushed grains with the help of a mixture of solvents, CHCl3 : CH3OH : H2O (1:1:0.9), at room temperature. Three main classes of lipids viz, neutral lipids, glycolipids and phospholipids, were then separated by column chromatography, on a silica gel column using diethyl either, acetone and methanol respectively as eluting solvents. Afterwards each class of lipid was further separated into its sub-classes using thin layer chromatography. The-neutral lipids were fractionated into hydrocarbons, sterol esters, -triglycerides, free fatty acids, diglycerides and sterols using solvent system, hexane: ether (85:15) and hexane: ether: acetic acid (80:20:2). The glycolipids were fractionated into monogalactosyldiglyceride and digalactosyldiglyceride by the solvent system CHCl3: CH3OH: H2O (75:25:3). Phospholipids, similarly, were separated into their sub-classes, viz, diphosphotidylglycerol, phosphotidylglycerol, phosphatidylethanalamine, phosphatidylinositol, phosphatidylserine, phosphatidylcholine and lysophosphatidylcholine, using CHCl3: CH3OH: NH3: H2O (65:35:4:0.2) as solvent system. During further investigations the fatty acid composition of all the classes were determined by gas chromatography. The neutral lipids were studied in detail. Triglycerides which comprised more than 50% of the neutral lipid class were investigated for the combination of fatty acids in their structures. This was done by collecting pure triglycerides by column chromatography using 2% diethyl ether in hexane as eluting solvent. Pure triglycerides were fractionated on AgNO3 plate. Silvernitrate impregnated TLC gave seven fractions, according to number of double bonds present in them, which were hydrolysed along-with the un-fractionated triglycerides using lipase, to obtain 2-mono-glycerides. The structure of the fatty acid attached at 2-position was determined by gas chromatography. The position of double bond present in the monoenoic fatty acids of triglycerides was found by oxidation of pure monoenoic acid using Von Rudolf technique. The mono and dicarboxylic acids produced as a result of oxidation were analyzed by gas chromatography and thus the information about the position of double bond present in the fatty acid was obtained. The identification of sterols present in neutral lipids was carried out in order to have an idea about the phytosterols of barley. The pure sterol fraction was obtained by saponifying the oil and extracting the unsaponifiable material with diethyl ether. The ethereal extract on TLC gave sterols and hydrocarbon. The pure sterols were then acetylated and fractionated by reversed phase thin layer chromatography as well as by gas chromatography. This gave three sterols which were identified as B-sito sterol, stigma sterol and compesterol. The hydrocarbon fraction was obtained by column chromatography, using hexane as eluting solvent, purified by TLC and was fractionated by argentation chromatography into four fractions using solvent system hexane:benzene (80:20). The whole hydrocarbons and its fractions were analyzed by GC and showed to give carbon chains from C13 to C37. The present investigations on the lipid classification of barley provides a first comprehensive study on the structure of triglyceride, position of double bond in monoenoic acids structure of sterols and the structure of hydrocarbons present in neutral lipids of Jao 87 and Jao 83, the two local varieties of Hordeum vulgare. These investigations also throw light on the relationship between the presence of useful constituents of lipids of barley and its importance as a nutritious as well as medicinal cereal.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Lipid Studies, Family Graminea, Hordeum Vulgare (Barley), Jao 87, Jao 83, Phospholipids, Glycolipids, Triglycerides, Sterols, Hydrocarbons, Neutral Lipids, Fatty Acid
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:343
Deposited By:Mr Ghulam Murtaza
Deposited On:27 Jun 2006
Last Modified:04 Oct 2007 21:00

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