CHEMISTRY OF LIPIDS. Dr. Huda Hania. Lipid chemistry . Lipid chemistry . Definition . Lipid compounds including: . Fats and Oils (triglyceride) Waxes Steroids Fat- soluble vitamins Phospholipid Mono- di glycerides . Classification of Lipids. Simple lipids.
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CHEMISTRY OF LIPIDS Dr. Huda Hania
Lipid chemistry Definition
Lipid compounds including: • Fats and Oils (triglyceride) • Waxes • Steroids • Fat- soluble vitamins • Phospholipid • Mono- di glycerides
Simple lipids The type of alcohols these are subclassified as They are esters of FA with various alcohols
Neutral Fats or Oils • Fats and oils are • also called triglycerides. • esters of glycerol+ 3 FA
WAXES When hydrolysis of waxes gives : one fatty acid + alcohol • EXAMPLES • Beeswax
Complex lipids Result of hydrolysis gives FA with alcohol and containing additional[prosthetic] groups. Subclassified according to the type of prosthetic group
Phospholipids FA + ALCOHOL + PHOSPHORIC ACID They frequently have nitrogen containing bases
Phospholipids Phospholipids may be classified on the basis of the type of alcohol present
A. Glycerophospholipids Alcohol is GLYCEROL Alcohol is SPINGOSINE • B. Spingophospholipids • Examples • Plasmalogens • Cardiolipins • Examples • Spingomyelins
Glycolipids FA + ALCOHOL[SPINGOSINE] +CARBOHYDRATE WITH NITROGEN BASE • They do not contain phosphate group • Example • Cerebrosides • Gangliosides
Lipoproteins • Chylomicrons • Very low density lipoprotein • (VLDL) • Low density lipoprotein (LDL) • High density lipoprotein (HDL) Lipid with prosthetic group PROTEIN
Derived lipids Derived from lipids (simple or complex)or precursors of lipids
Fatty acidsare • long-chain carboxylic acids. • typically 12-18 carbon atoms. • insoluble in water. • saturated or unsaturated.
Fatty acids are saturated with all single C–C bonds. unsaturated with one or more double C=C bonds. are solids at room temperature • are liquids at room temperature.
Chemical tests for: • Precursor of many steroid hormones, vitamin D • Solubility in polar and nonpolar solvent • Emulsification • Oxidation of unsaturation FA • Qualitative analysis of detection in natural products ( salkowski reaction)
Solubility in polar and nonpolar solvent • Reagents • Olive oil (vegetable oil), butter (animal fat), • stearic acid (saturated fatty acid), oleic acid (unsaturated fatty acid), • Solvents: dilute acid and alkali solutions, cold alcohol, hot alcohol, benzene, chloroform, ether and carbon tetrachloride. • Procedure • 1. Add a 2drops of the liquid fat or 0.1 g of the solid fat in labeled test tubes. • 2. To each test tube add a 1 ml of solvent and write down your observations. • 3. Repeat the experiment with a different solvent and make your observations.
2- Emulsification Reagents • Neutral olive oil, 0.5 % Na2C03, Rancid olive oil Procedure 1. Shake up a drop of neutral olive oil with a little water in a test tube, the fat becomes finally divided forming an emulsion, upon standing fat separates and rises to the top. 2. To 5 ml water in a test tube add 2 to 3 drops of 0.5 percent Na2CO3. Introduce a drop of neutral olive oil and shake, the emulsion is not permanent and is not so transitory. 3. Repeat step 2 using rancid olive oil. In this case the alkali combines with the free fatty acids to form soap and the soap being an emulsifying agent, it emulsifies the fat.
2- Emulsification • An emulsion is a mixture of two or more liquids that are normally immiscible(no mixable). • Bile Salts Synthesized from cholesterol and stored in the gallbladder When you eat fat, the bile salts act as soap and help emulsify the large globules of fat. A. Two immiscible liquids, not yet emulsifiedB. An emulsion of Phase II dispersed in Phase IC. The unstable emulsion progressively separatesD. The surfactantstabilizing the emulsion
Oxidation of unsaturation FA • Into test tube place one drop of oil and 3 ml of Na2CO3 • Warm it slightly and drop solution KMnO4 .after each drop the violet color disappear • The end of the reaction recognized by ppt brown solid MnO2
4-Qualitative analysis of detection in natural products ( salkowski reaction)
O R O R C O R OH C H R O Carboxylic Acid Alcohol Ester