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Lipid chemistry V2 By Dr Anurag Yadav
- 1. MNR MEDICAL COLLEGE & HOSPITAL Dr Anurag Yadav MBBS, MD Assistant Professor Department of Biochemistry Instagram page –biochem365 Email: [email protected]
- 2. OBJECTIVE Why do we need to study lipid chemistry Definition Functions Classification Fatty Acid
- 3. Constituents of diet Carbohydrates Proteins Lipids Vitamins Minerals water
- 4. Why do we need to study lipid chemistry
- 9. DEFINITION: The lipids are a heterogeneous group of compounds, have the common property of being (1) relatively insoluble in water and (2) soluble in non-polar solvents such as ether, benzene and chloroform.
- 10. Functions of lipids 1) Structural components of cell membranes (phospholipids, cholesterol) 2) Storage form of energy (triglycerides).
- 11. 3) Provides insulation against changes in external temperature. 4) Give shape and contour to the body. 5) Protect internal organs by providing a cushioning effect
- 12. 6) Acts as surfactant, prevents lung collapse. 7) They act as metabolic regulators (Steroid hormones & Prostaglandinds- local hormones) 8) Helps in absorption of fat soluble vitamins in food.
- 13. 9) Acts as electrical insulators – helps in propogation of nerve 10) Lipids gives taste and palatability to food.
- 14. Cell membrane Energy Insulation Shape Protects organs Surfactant Metabolic regulators Fat soluble vitamins Tasty food
- 16. SIMPLE LIPIDS Esters of Fatty acid with alcohol Ex- Fats & Oil Waxes
- 19. PHOSPHO LIPIDS NITROGEN CONTAINING GLYCEROPHOSPHO LIPIDS LECITHIN CEPHALIN NON NITROGEN GLYCERPHOSPHO LIPIDS PHOSPHATIDYL INOSITOL PHOSPHATIDYL GLYCEROL DIPHOSPHATIDYL GLYCEROL PLASMALOGENS CHOLINE PLASMALOGEN ETHANOLAMINE PLASMALOGEN PHOSPHO SPHINOSIDES SPINGOMYELIN
- 21. CLASSIFICATION OF LIPIDS. LIPIDS SIMPLE TAG WAX COMPOUND PHOSPHOLIPIDS NON-PHOSPHOLIPIDS DERIVED FATTY ACIDS STEROIDS PROSTAGLANDINS OTHERS LIPOPROTEINS
- 22. FATTY ACIDS DEFINITON: fatty acids carboxylic acids with hydrocarbon side chain General formula: R-CO-OH.
- 23. CLASSIFICATION OF FATTY ACIDS FATTY ACID TOTAL NO.OF C ATOMS EVEN CHAIN ODD CHAIN LENGTH OF CHAIN SHORT CHAIN MEDIUM CHAIN LONG CHAIN VERY LONG CHAIN NATURE OF HYDRO CARBON SATURATED UNSATURATED BRANCHED CHAIN HYDROXY FA
- 24. TOTAL NO.OF C ATOMS EVEN CHAIN • C4 butyric acid • C6 caproic acid • C8 caprylic acid • C10 capric acid • C12 lauric acid • C14 myristic acid • C16 palmitic acid • C18 stearic acid • C20 arachidic acid ODD CHAIN • C3 propionic acid
- 25. LENGTH OF CHAIN
- 26. SATURATED FATTY ACIDS Saturated FA do not contain double bonds General formula: CH3-(CH2)n-COOH.
- 29. UNSATURATED FATTY ACIDS FATTY ACIDS containing one or more double bonds Subdivide as follows- 1. Monounsaturated- contain 1 double bond. 2. Polyunsaturated – contain 2 or more double bonds 3. Eicosanoids- derived from eicosa polyenoic fatty acids, comprise of prostanoids(PG,PGI,TX), leukotrienes, lipoxins.
- 31. MONO UNSATURATED FA Contains one double bond. Eg: • C16 palmitoleic acid • C18 oleic acid
- 32. PUFA Contain 2 or more double bonds Examples- linoleic acid 18C, 2 double bond, ω6 family. linolenic acid18C, 3 double bond, ω3 family. arachidonic acid 20C, 4 double bond, ω6 family. Nutritionally essential, hence called ESSENTIAL FATTY ACIDS. PG,PGI,TX are derived from arachidonic acid . Docosa hexa enoic acid (DHA) present in fish oil. High concentration found in retina, cerebral cortex, sperms.
- 34. Essential fatty acids DEFINITION: These fatty acids cannot be synthesized by the body and therefore should be supplied in the diet. found in vegetable oils fish oils. EX: Linoleic acid, linolenic acid , arachidonic acid FUNCTIONS: ➢ Synthesis of eicosanoids. ➢ PUFA -EFA are required for membrane structure and function. Increase fluidity of membrane because of cis configuration
- 35. ➢ Esterification of cholesterol & excretion or transport of cholesterol. They are hypocholesterolemic and hence anti- atherogenic effect. ➢The omega-3 FA decrease VLDL and LDL. lowers the risk of cardiovascular diseases ➢Prevents dermatitis, eczema in children. ➢Excess of PUFA may lead to production of free radicals.
- 36. Clinical significance Deficiency of EFA causes acanthocytosis, hyperkeratosis, acrodermatitis, hypercholesterolemia. EFA deficiency is linked with heart attacks, insulin resistance, obesity.
- 38. PROPERTIES OF FATTY ACIDS HYDROGENATION: Hydrogenation of double bonds. Unsaturated→ saturated fatty acids Ex: Linolenic→linoleic→oleic→stearic. HALOGENATION: When treated with halogens, unsaturated fatty acid take up 2 halogen atom at double bond to form Halogenated Derivative of fatty acid. Ex: oleic acid +I2→ Di-iodo oleic acid. Index of unsaturation.
- 39. MELTING POINT :at 25oC Short & medium chain FA – liquids Long chain FA—solids UNSATURATED FA→ LOWER MELTING POINT compared to SATURATED FA. SALT FORMATION: SATURATED & UNSATURATED FA form salts with alkali. Sodium ,potassium, Calcium ,Magnesium salts of long chain FA called→ SOAPS.
- 40. ESTER FORMATION: SATURATED & UNSATURATED FA form ester with alcohols. OXIDATION OF FA: All FA undergo beta oxidation in body to give energy .
- 41. NEUTRAL FATS/TAG Simple and mixed TAG Simple- Tripalmitin, Triolein Mixed – 1,3 dipalmitoyl-2-olein Physical properties of TAG -HYDROPHOBIC -oils are liquids at room temp -fats are solids at room temp Storage form of energy in 70kg man 11kg is TAG
- 42. Properties of fats 1. Melting point- TAG of saturated FA → have higher melting points and TAG of unsaturated FA→ have lower melting point. 2. Solubility – fats are insoluble in water but soluble in nonpolar organic fat solvents.
- 43. Micelle Emulsification • on adding emulsifying agents each fat droplet gets covered on its surface by thin layer of the emulsifying agent whose polar group are oriented towards the surrounding aqueous phase. Such molecular aggregates are called micelles, remain stable in water to form aqueous emulsion of fat.
- 44. 4. Hydrolysis - Lipases 5. Saponification- alkaline hydrolysis of fats resulting in soap formation is known as Saponification. Saponification number – defined as the number of milligram of KOH required to saponify 1gm of fat. Saponification number is inversely proportional to the chain length. Its an indication of molecular weight of fat. Example: Human fat-194-198 Butter 210-230 Coconut oil 252-262
- 45. 6.IODINE NUMBER :of a fat is defined as the number of grams of iodine taken up by 100 grams of fat. It is the index of the degree of unsaturation & is directly proportional to the content of the unsaturated fatty acids. Higher the iodine number, higher is the degree of unsaturation. Example: Coconut oil 7-10 Butter 28 Sunflower oil 145-150
- 46. 7. RANCIDITY Appearance of unpleasant smell and taste of fats and oils on standing. it occurs on exposure to air, moisture, warm temperature, uv light. a. hydrolytic rancidity. b. oxidative rancidity.
- 47. Hydrolytic rancidity -is due to the partial hydrolysis of TAG molecules due to traces of hydrolytic enzymes present in naturally occurring fats/oils. Oxidative rancidity -is the result of partial oxidation of unsaturated FA with resultant formation of epoxides and peroxides of small molecular weight FA by peroxides and free radicals. short chain aldehydes and ketones are formed.
- 48. Waxes Are esters of higher fatty acids(FA) with higher monohydroxy aliphatic alcohols. They have very long straight chains. eg beewax, lanolin(bootwax).
- 49. PHOSPHOLIPID
- 50. GLYCEROPHOSPHOLIPIDS Phosphatidic acid. Phosphatidyl choline(lecithin). Phosphatidyl ethanolamine(cephalin). Phosphatidyl serine. Phosphatidyl inositol. Phoshatidyl glycerol(cardiolipin). Plasmalogens.
- 52. Phosphatidic acid It is made up of one glycerol to which two FA residues are esterified to carbon atoms 1 and 2 and the third hydroxyl group is esterified to a phosphoric acid.
- 53. Lecithin They have a nitrogenous base choline bound to the phosophate group. Predominant glycerophospholipid in cell membrane
- 54. FUNCTIONS Acts as storage for body's choline reserve Helps cholesterol dissolve in bile Emulsification of lipids & its absorption in GI tract The lecithin-sphingomyelin ratio of the amniotic fluid is a index of fetal maturity. Estrification of cholesterol As part of lipoprotein it helps transport of fat Provides arachidonic acid for Eicosanoid synthesis
- 55. A1 – Acylglycerophosphoryl choline + FA A2 – lysoleithin + FA C – 1,2 diacylglycerol + PhosphorylCholine D – phosphaitdic acid + Choline CHOLIN Action of Phospholipase
- 56. LUNG SURFACTANT CONSTITUENTS Dipalmitoyl lecithin - Cholesterol Surfactant protein A, B, C - Phosphotidyl glycerol Produced by – Alveolar epithelial cells It decreases the surface tension of aqueous layer of the lung & prevents collapse of lung alveoli Fetal life before 28wks Sphingomylein Matured fetus more Lecithin The lecithin –Sphingomylein (L/S) ratio of amniotic fluid – INDEX OF FETAL MATURITY
- 57. RESPIRATORY DISTRESS SYNDROME Defect in synthesis of DIPALMITOYL LECITHIN Premature infants – higher incidence
- 58. Cephalin They have nitrogenous base ethanolamine bound to the phosphate group. It is found in biomembranes.
- 59. Phosphatidyl serine Here amino acid serine is esterified to the phosphate residue. They occur in brain, erythrocytes.
- 60. Phosphatidyl inositol Here phosphatidic acid is esterified to inositol. Phosphatidyl inositol biphosphate or PIP-2 is present in biomembranes. This compound plays a vital role in the mediation of harmone action on biomembranes.
- 61. SPHINGOPHOSPHOLIPIDS These phospholipids carry sphingosine(is a nitrogenous dihydroxy, C 18 alcohol).
- 62. Sphingomyelin occurs in brain, liver, cardiac muscle. Sphingomyelins are located in the nerve cell membranes. They account for 25% of lipids in myelin sheath. Acts as an emulsifying agent and detergent. The ratio of proportion of lecithin and sphingomyelin is important in biological fluids like bile amniotic fluid etc.
- 63. FUNCTIONS OF PHOSPHOLIPID Component of cell membrane – regulate cell permeability Amphipathic in nature
- 64. MICELLAR FORMATIO Phospholipids in water – micelle formation Involved in solublization of lipids in aqueous medium & help in digestion & absorption of Lipids
- 65. LIPOSOMES Sonication of mixture of Phospholipid & cholesterol Microscopic spherical vesicles Drugs, proteins, enzymes, genes – carried to target organs Important application in Cancer chemotherapy, Gene therapy, Vaccines, Diagnostic imaging
- 66. Couple oxidative phosphorylation – ETC Source of Arachidonic acid – precursor of Eicosanoids Second mesanger – Phosphatidyl Inositol Role in blood coagulation Surfactant Transport of Cholesterol
- 67. GLYCOLIPIDS These are carbohydrate lipid complexes. Each molecule contains sphingosine, a fatty acid molecule and a carbohydrate molecule. CEREBROIDES GLOBOSIDES GANGLIOSIDES Carbohydra te
- 68. Lipoproteins Macromolecular complex of lipid & protein that transport insoluble lipids through the blood b/w different organs & tissues Consists of lipid core – TAG & Cholesterol esters Single layer of Amphiphatic phospholipids & free cholesterol with some proteins
- 69. The protein part of the lipoprotein is called as apolipoprotein 4 major types Apo A , Apo B, Apo C, Apo E 3 subgroups I, II, III
- 70. Classification of lipoproteins Chylomicrons VLDL or pre beta lipoproteins. LDL or beta lipoproteins. HDL or alpha lipoproteins.
- 72. Chylomicrons Transport form of dietary triglycerides to be delivered to adipose tissue for storage and to muscle & heart for their energy needs. Synthesized in the Intestine The TAG, cholesterol ester and phospholipid molecules along with apoproteins B48, apo- C are incorporated into chylomicrons. The half life of chylomicrons in blood is about 1 hr.
- 74. VLDL Major carriers of endogenous TG from Liver to peripheral tissues Synthesized in the liver Contains apo-B-100, C-II, apo-E Half life 1-3hrs.
- 75. LDL Cholesterol rich lipoproteins containing only apo-B-100. About 75% of plasma cholesterol is incorporated into LDL particles. Most of the LDL is derived from VLDL Half life 2 days. LDL transports cholesterol from liver to the peripheral tissues. LDL concentration in blood has a positive co- relation with the incidence of cardiovascular disease. BAD cholesterol.
- 77. HDL Main transport form of cholesterol from peripheral tissues to liver. It is anti-atherogenic. HDL<35mg/dl increase risk of CVD. HDL>60mg/dl protects from CVD.
- 78. LIPOPROTEIN a Variant of LDL Synthesized in Liver Composition – same as LDL but ApoB 100 is linked by disulphide bond to Apoa (Glycoprotein) Interferes with fibrinolysis Plasma levels <0.3gm/dL Elevated levels --- increased risk of CVD
- 79. STEROLS Sterols are structural lipids present in the membrane of most of the eukaryotic cells Cholesterol is a major animal Sterol
- 80. CHOLESTEROL It is a derived lipid. Consists of sterol nucleus Total cholesterol <200mg/dL Structure- CPPP Most of it is as Cholesterol ester
- 81. CH3 CH3 HO Steroid ring 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 A B C D CYCLOPENTANOPERHYDROPHENANTHRENE
- 83. Functions 1) Structural component of cell membranes- influences membrane permeability 2) Insulator for nerve fibers 3) Precursor for synthesis of biologically important products Steroid hormones Glucocorticoids, Mineralocorticoids, Androgens, Estrogen, Progesterone Bile acids – acts as emulsifying agents, helps in digestion & absorption of dietary fats Vitamine D – regulates Calcium & Phosphorus metabolism
- 84. 4) Essential ingredient of lipoproteins. 5) Fatty acids are transported to liver as cholesterol esters. 5) The level of cholesterol in blood is of primary importance due to its role in the development of atherosclerosis.
- 85. Bile acids: They are produced from oxidation of cholesterol in the liver producing cholic and chenodeoxycholic acids that are conjugated with glycine or taurine to produce glycocholic, glycochenodeoxycholic, taurocholic and taurochenodeoxycholic acids. They react with sodium or potassium to produce sodium or potassium bile salts.
- 86. Function is as follows: 1.Emulsification of lipids during digestion. 2.Help in digestion of the other foodstuffs. 3.Activation of pancreatic lipase. 4.Help digestion and absorption of fat- soluble vitamins. 5.Solubilizing cholesterol in bile and prevent gall stone formation. 6.Choleretic action (stimulate their own secretion).
- 87. EICOSANOIDS Biologically active molecules Types Prostaglandins (PG) Prostacyclins (PI) Thrombaxanes (TX) Leukotrines (LT)
- 88. Biosynthesis of Eicosanoids PHOSPHOLIPASE A2 ATTACKS MEMBRANE PHOSPHOLIPID RELEASE OF ARACHADONIC ACID CYCLOOXYGENASE lipoxygenase PG’S TX LEUKOTRINES
- 89. ARACHADONIC ACID Cyclooxygenase Lipooxygenase PGG2 5-Hydroxyecosatetraenoic acid Peroxidase LTA4 PGH2 LTB4 LTC4 LTD4 LTE4 TXA2 PGE2 PGF2a PGI2 PGD2
- 90. BIOLOGICAL ACTIONS & CLINICAL SIGNIFICANCE 1. Inflammation 2. Regulation of BP 3. Effect on platelet aggregation 4. Effect on Uterus 5. Effect on Gastrointestinal system 6. Effect on Respiratory system 7. Effect on Metabolism 8. Effect on Renal system
- 91. Inflammation Eicosanoids are mediators of inflammation Effect on platelet aggregation Thrombaxanes TXA2 causes platelet aggregation Prostacyclins PGI2 inhibit Platelet aggregation
- 92. Effect on Respiratory system PGE -- Bronchodilator PGF – Bronchoconstrictor Effect on Metabolism PGE – decreases lipolysis, increases glycogenesis Effect on Renal system PGE – increases glomerular filtration rate
- 93. Effect on Uterus Stimulates uterine contraction Effect on GI system Increases intestinal motility and inhibit gastric acid secretion
- 94. TYPE SITE FUNCTION PGE2 MOST TISSUES VASODILATION , SMOOTH MUSCLE RELAXATION INDUCE LABOUR PGF2a MOST TISSUES VASOCONSTRICTION, SMOOTH MUSCLE CONSTRICTION BRONCHOCONSTRICTION , STIMULATES UTERINE CONTRACTIONS PGI2 ENDOTHELIUM OF VESSELS VASODILATION INHIBITS PLATLET AGGREGATION TXA2 PLATELETS PLATELET AGGREGATION, VASOCONSTRICTION, SMOOTH MUSCLE CONSTRICTION, BRONCHOCONSTRICTION LT LEUCOCYTES, PLATELETS VASOCONSTRICTION, BRONCHOCONSTRICTION , INCREASE CELLULAR PERMEABILITY
- 95. Spingolipidosis or lipid storage disorders
- 96. Dr Anurag Yadav MBBS, MD Assistant Professor Department of Biochemistry Instagram page –biochem365 Email: [email protected]