1. Faculty of Medicine, U of D
Lipid Biochemistry
For nurse Faculty
By Dr Rehab Omer
Faculty of Medicine, U of D

2. LIPIDS
Are groups of heterogeneous compounds characterized by their solubility properties.
They are insoluble in water, but are soluble in organic solvents such as ether, chloroform, and benzene…

3. Biomedical Importance of Lipids
1. Important dietary constituents
2. High energy content; labile and storage
3. Fat-soluble vitamins; A, D, E and K.
4. Important cellular constituent (membrane structure)
5. Thermal insulators in subcutaneous tissues
6. Electrical insulators (Myelinated nerves)
7. Precursors of various hormones (steroid hormones and Eicosanoids).
8- Knowledge of lipid biochemistry is necessary in understanding many important biomedical areas, eg, obesity, diabetes mellitus, atherosclerosis

4. Classification of Lipids
1. Simple 1 Lipids
a. Fats and (triacylglycerol or triglyceride)
b. Waxes
2. Complex Lipids
a. Phospholipids
b. Glycolipids
3. Derived lipids or lipids with specific biological activity.

5. Classification Simple lipids: fatty acids + alcohol.
Fats: Esters of fatty acids with glycerol. Oils are fats in the liquid state.
Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols.
Complex lipids: fatty acids + alcohol + additional group (AG)
Phospholipids: Fatty Acid + Alcohol + phosphoric acid + AG

6. Classification
glycerophospholipids the alcohol is glycerol and in sphingophospholipids the alcohol is sphingosine.
Glycolipids (glycosphingolipids): fatty acid + sphingosine + carbohydrate
Precursor and derived lipids: These include fatty acids, glycerol, steroids, ketone bodies, lipid-soluble vitamins, and hormones

7. Simple lipids

8. Fats or oils; Acylglycerols such as Triacylglycerols
Esters of fatty acids with glycerol; mono-di- or triacylglycerol (TAG).
The main storage form of fuel in animals is TAG.
It is stored in adipose tissues.
It is hydrophobic molecule, therefore it is transported in blood by the lipoprotein particles mainly chylomicrons and very low density lipoprotein (VLDL)

9. Fat: A mixture of triacylglycerols that is solid because it contains a high proportion of saturated fatty acids.

10. Oil: A mixture of triacylglycerols that is liquid because it contains a high proportion of unsaturated fatty acids.

11. Properties of Fats and Oils:
Triacylglycerols in natural fats and oils are nonpolar, hydrophobic molecules with no ionic charges (uncharged) neutral lipid.

14. Atif Hassan Khirelsied
Fatty acids
Long chain carboxylic acids.
Structural components and precursors of different lipids
Naturally occur as even No. carbon compounds.
Fatty acids that occur in natural fats are usually straight-chain (not branched)
Transported in blood bound to albumin because they are hydrophobic
May be saturated or unsaturated.
Atif Hassan Khirelsied

15. Fatty Acids Are aliphatic carboxylic acids The chain may be
saturated (containing no double bonds)
Pamitic Acid
or Unsaturated (containing one or more double bonds).
Palmitoleic Acid

16. Atif Hassan Khirelsied

17. Fatty Acids Unsaturded fatty are further divided into:
(1) Monounsaturated (monoethenoid, monoenoic) containing one double bond.
(2) Polyunsaturated (polyethenoid, polyenoic) containing two or more double bonds.
And into Cis and Trans forms

18. Fatty Acids Nomenclature
-oic being substituted for the final –e of the name of carbon atoms (eg, Propionic acid)
Saturated acids end in -anoic, eg, octanoic acid, and unsaturated acids with double bonds end in -enoic, eg, octadecenoic acid (oleic acid)
Carbon atoms are numbered from the carboxyl carbon (carbon No. 1)

19. Atif Hassan Khirelsied
Fatty acids
The carbon atoms adjacent to the carboxyl carbon (Nos. 2, 3, and 4) are also known as the α, β, and γ carbons
The terminal methyl carbon is known as the ω or n-carbon
Atif Hassan Khirelsied

20. The numeric designations
The numeric designations used for fatty acids come from the number of carbon atoms, followed by the number and sites of unsaturation (eg, palmitic acid is a 16-carbon fatty acid with no unsaturation and is designated by 16:0).
Atif Hassan Khirelsied

21. Fatty Acids Nomenclature
Δ for indicating the number and position of the double bonds
eg, Δ9 indicates a double bond between carbons 9 and 10 of the fatty acid
18:1;9 or Δ9 18:1
ω9 indicates a double bond on the ninth carbon counting from the ω- carbon
ω9,C18:1 or n–9, 18:1

22. The numeric designations
The site of unsaturation in a fatty acid is indicated by the symbol ∆
The number of the first carbon of the double bond (e.g. palmitoleic acid is a 16-carbon fatty acid with one site of unsaturation between carbons 9 and 10, and is designated by (16:1; ∆9).
Atif Hassan Khirelsied

23. Arachiodonic acid poly unsaturated fatty acid with 20 carbons and four double bonds between 5 and 6, 8 and 9, 11 and 12, 14 and 15;
20:4Δ5,8,11,14

24. Physiologically Important Fatty Acids Saturated
12: Dodecanoic Acid Lauric Acid
14: Tetradecanoic Myristic Acid
16: Hexadecanoic Palmitic Acid
18: Octadecanoic Stearic Acid
20: Eicosanoic Arachidic Acid

25. Physiologically Important Fatty Acids Unsaturated
cis-9-Hexadecenoic Palmitoleic acid
cis-9-Octadecenoic Oleic acid
cis-,cis-9,12-Octadecadienoic Linoleic acid
All Cis, 9,12,15 Octadecatrienoic acid Linolenic acid
All Cis 5,8,11,14-Ecosatetraenoic acid Arachidonic acid

26. Fatty acids
Saturated fatty acids of less than eight carbon atoms are liquid at physiological temperature, whereas those containing more than ten are solid.
The presence of double bonds in fatty acids significantly lowers the melting point relative to a saturated fatty acid.

27. Atif Hassan Khirelsied
Fatty acids
Are synthesize in the body
Some are not synthesized in animal body, thus are dietary essential, linoleic acid and linolenic acid, containing unsaturation sites beyond carbons 9 and 10
linoleic,(ω6) found in vegetable oil eg olive oil soyabean corn oil it lower serum LDL cholesterol and so cardiovascular disease and precursor of eicosanoid.
linolenic acids (ω3) found in fish important for brain development in infant and precursor of eicosanoid.
Atif Hassan Khirelsied

28. Waxes: Biological waxes are esters of long-chain (C14 to C36) saturated and unsaturated fatty acids with long-chain (C16 to C30) alcohols.

29. Beeswax

30. Complex lipids

31. phospholipids

32. Sphingophospholipids
Glycerophosphlipids
Phospholipids
Sphingophospholipids
Atif Hassan Khirelsied

33. Atif Hassan Khirelsied
Phospholipids
Are important constituents of cellular membranes.
Are classified to glycerophospholipids
and sphingophospholipids according to their alcoholic constituent.
Atif Hassan Khirelsied

34. Phosholipids are the main lipid constituents of membranes
Phosholipids are the main lipid constituents of membranes. Derivatives of phosphatidic acid.

36. Phosphatidic acid:
Glycerol + 2 fatty acids + phosphoric acid

39. Atif Hassan Khirelsied
What do we mean by a nitrogenous base and additional group?
Choline
Ethanolamine
Serine.
Inositol.
Atif Hassan Khirelsied

40. Phosphatidyl choline (lecithins):
Phosphtidic acid + choline

41. Phosphatidyl choline (lecithin) occur in the cell membranes.

42. Atif Hassan Khirelsied1.
Lecithins
Are important constituent of plasma membrane.
Are particularly abundant in nerve tissues
Store choline required for the formation of acetylcholine in CNS.
Lecithin
Atif Hassan Khirelsied

43. Dipalmitoyl lecithin is the major constituent of the lung surfactant preventing adherence due to surface tension of the inner surface of the lungs.
Deficiency of the lung surfactant may seen in preterm new born, which causes infant respiratory distress syndrome (IRDS)

44. Phosphatidylethanolamine(cephalin):
Phosphatidic acid + ethanolamine
Found in cell membranes.

46. Phosphatidyl serine: Found in cell membranes.
Phosphtidic acid + serine
Found in cell membranes.

48. Phosphatidyl inositol:
Phosphatidic acid + inositol

50. A precursor of second messenger
A precursor of second messenger. Important constituent of cell membrane phospholipids.

51. Plasmalogens: Brain & Muscles,10% of their phospholipids.
Structurally plasmalogens resemble phosphatidyl ethanolamine but have ether link at C1(NOT ester).

53. Cardiolipin: 2 phosphatidic acid + glycerol
Diphosphatidyl glycerol→
2 phosphatidic acid + glycerol
Major lipid of mitochondrial membrane

55. Are intermediates in the metabolism of phosphoglycerols
Lysophospholipids
Are intermediates in the metabolism of phosphoglycerols

57. Sphingomyelins: Brain & nerve tissue
Sphingosine + fatty acid + phosphoric acid+ choline.
Sphingosine + fatty acid→ Ceramide

59. Glycolipids : Glycosphingolipids
Classes of glycosphingolipids:
Cerebrosides: Ceramide + Glucose or Galactose.
Sulfatides: sulfuric acid esters of galactocerebrosides.
Globosides: contain 2 or more sugars.
Gangliosides: similar to globosides except also contain sialic acid.

60. Ceramide + one or more sugars

61. Galactosylceramide: Galactose + ceramide
is a major glycosphingolipid of Brain & Nerve tissue.

62. Sulfatides: Sulfogalactosylceramide
present in high amount in myelin.

64. Gangliosides
Glycoshingolipids derived from glucosylceramide that contain one or more molecules of sialic acid (neruaminic acid).

66. Ganglioside

67. Gangliosides present in high concentration in nervous tissues.

68. Lipoproteins
Combinations of lipid and protein for transporting lipids in the blood.

69. Lipoproteins

70. Lipoproteins
1.Chylomicron
2.VLDL
3.LDL
4.HDL

71. Precursor & derived lipids
Fatty acids
Glycerol
Steroids
ketone bodies
Lipid-soluble vitamins

73. Cholesterol
Amphipathic lipid
Sterol
Derived from the steroid nucleus

77. Importance Constituent of cell membrane Synthesis of steroid hormones
Synthesis of vitamin D
Synthesis of bile salts

78. Eicosanoids (local hormones)
They are derivatives of arachidonic acid
Include:
Prostaglandins
Prostacyclins
Thromboxanes
Leukotrienes
lipoxins

79. Amphipathic lipids self-orient at oil: water interface.

82. Lipids Peroxidation
Peroxidation (Auto-oxidation) is the exposure of lipids to oxygen
Responsible for deterioration of foods (rancidity)
For damage to tissues in vivo, where it may be a cause of cancer, inflammatory diseases, atherosclerosis, and aging
The deleterious effects are considered to be caused by free radicals (ROO•, RO•, OH•)
Vitamin C and E are used as antioxidant