Lipids are non-polar compounds that include fatty acids, triglycerides, phospholipids, and sterols. They function in energy storage, cell membrane structure, insulation, and hormone production. Fatty acids are the building blocks of lipids and contain long hydrocarbon chains with a carboxyl group at one end. Saturated fatty acids contain only single bonds while unsaturated have one or more double bonds. Phospholipids like phosphatidylcholine are amphipathic and form bilayers that make up cell membranes. Membrane lipids also include cholesterol and sphingolipids such as sphingomyelin and cerebrosides.

1. Introduction
 Definition: water insoluble compounds
 Most lipids are fatty acids or ester of fatty acid
 They are soluble in non-polar solvents such as petroleum ether,
benzene, chloroform
 Functions




Energy storage
Structure of cell membranes
Thermal blanket and cushion
Precursors of hormones (steroids and prostaglandins)
 Types:
 Fatty acids
 Neutral lipids
 Phospholipids and other lipids

2. Classification:
Saponifiable—can be hydrolyzed by
NaOH to make soap
Non-saponifiable—cannot be
hydrolyzed, includes sterols such as
cholesterol
Saponifiable lipids are further subdivided:
Simple- made of fatty acids plus
alcohol
Compound- either phospho- or
glyco- lipids, which contain phosphate or
sugar groups as well as fatty acids

3. Lipids are non-polar (hydrophobic) compounds, soluble in organic solvents.
Most membrane lipids are amphipathic, having a non-polar end and a polar end.
Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end.
-
A 16-C fatty acid: CH3(CH2)14 COO
Non-polar
-
polar
A 16-C fatty acid with one cis double bond between
represented as 16:1 cis ∆ 9.
C atoms 9-10 may be

5. Double bonds in fatty acids
usually have the cis configuration.
Most naturally occurring fatty
acids have an even number of
carbon atoms.
γ
4
β
3
α
2
O
C
1
O−
fatty acid with a cis-∆9
double bond
Some fatty acids and their common names:
14:0 myristic acid; 16:0 palmitic acid; 18:0 stearic acid;
18:1 cis∆9 oleic acid
18:2 cis∆9,12 linoleic acid
18:3 cis∆9,12,15 α-linonenic acid
20:4 cis∆5,8,11,14 arachidonic acid
20:5 cis∆5,8,11,14,17 eicosapentaenoic acid (an omega-3)

7. γ
4
β
3
α
2
O
C
1
O−
fatty acid with a cis-∆9
double bond
There is free rotation about C-C bonds in the fatty acid
hydrocarbon, except where there is a double bond.
Each cis double bond causes a kink in the chain.
Rotation about other C-C bonds would permit a more
linear structure than shown, but there would be a kink.

9. Fats & Oils
Simplest lipids, called triacylglycerols or
simply triglycerides. Main form of fat
storage in plants, animals, and man.
Males store 21% fat on average, females
26%.

10. Essential Fatty
Acids
Fatty acids which cannot be made by the body, but are
important for health and growth are called essential.
Linolenic acid, found mostly in vegetable oils, is an
important reducer of LDL (low density lipoproteins),
which help to take cholesterol into the blood and
cause atherosclerosis (buildup of plaque in the blood
vessels) a prime cause of heart attacks
Arachidonic acid is important in making eicosanoids,
molecules which regulate and protect the body from
invasion by microorganisms.

11. Simple Lipids—Fatty Acids
Simple triglycerides contain the same fatty
acid in all three positions; mixed
triglycerides contain two or three different
fatty acids
Fatty acids are carboxylic acids with from 4 to
20 carbons in the chain. The chain can be
saturated (only single bonds) or
unsaturated (one or more double bonds in
the chain), Saturated are usually solid at
room temperature, unsaturated are usually
liquid

13. Less common fatty acids
H3 C
 iso – isobutyric acid
 anteiso
R
H3 C
R
H3C
CH3
 odd carbon fatty acid – propionic acid
 hydroxy fatty acids – ricinoleic acid,
dihydroxystearic acid, cerebronic acid
 cyclic fatty acids – hydnocarpic, chaulmoogric
(CH2)12-CO2H
(CH2)10-CO2H
acid
chaulmoogric acid
hydnocarpic acid

14. H3C
COOH
CH3
CH3
CH3
CH3
PHYTANIC ACID
A plant derived fatty acid with 16 carbons and branches at C 3, C7, C11 and
C15. Present in dairy products and ruminant fats.
A peroxisome responsible for the metabolism of phytanic acid is defective
in some individuals. This leads to a disease called Refsum’s disease
Refsum’s disease is characterized by peripheral polyneuropathy, cerebellar
ataxia and retinitis pigmentosa

15. Less common fatty acids
H3C
(CH2)10 C
C
(CH2)4 COOH
TARIRIC ACID
H2C
CH
(CH2)4 C
C
C
C
(CH2)7 COOH
ERYTHROGENIC ACID
These are alkyne fatty acids

16. Unsaturated fatty acids
 number and position of the double
bond(s)Various conventions are in use for
indicating the
18
H3C (CH2)7
H
C
1
9
CH(CH2)7COOH
10
9
18:1,9 or ∆ 18:1
ω
H3C
n
2 3 4
5 6 7 8 9
10
CH2CH2CH2CH2CH2CH2CH2CH
17
ω
9, C18:1 or n-9, 18:1
18
CH(CH2)7COOH
10
9
1

17. Unsaturated fatty acids
 Monoenoic acids (one double bond):
 16:1, 9 ω7: palmitoleic acid (cis-9-hexadecenoic acid
 18:1, 9 ω9: oleic acid (cis-9-octadecenoic acid)
 18:1, 9 ω9: elaidic acid (trans-9-octadecenoic acid)
 22:1, 13 ω9: erucic acid (cis-13-docosenoic acid)
 24:1, 15 ω9: nervonic acid (cis-15-tetracosenoic acid)

18. Unsaturated fatty acids
 Trienoic acids (3 double bonds)
 18:3;6,9,12 ω6 : γ-linolenic acid (all cis-6,9,12octadecatrienoic acid)
 18:3; 9,12,15 ω3 : α-linolenic acid (all-cis-9,12,15octadecatrienoic acid)
 Tetraenoic acids (4 double bonds)
 20:4; 5,8,11,14 ω6: arachidonic acid (all-cis-5,8,11,14eicosatetraenoic acid)

19. Unsaturated fatty acids
 Pentaenoic acid (5 double bonds)
 20:5; 5,8,11,14,17 ω3: timnodonic acid or EPA
(all-cis-5,8,11,14,17-eicosapentaenoic acid)*
 Hexaenoic acid (6 double bonds)
 22:6; 4,7,10,13,16,19 ω3: cervonic acid or DHA
(all-cis-4,7,10,13,16,19-docosahexaenoic acid)*
Both FAs are found in cold water fish oils

20. Waxes
Waxes are simple lipids which are esters of long chain
alcohols and fatty acids. Beeswax is a 30 C alcohol
connected to a 16 C fatty acid
Waxes are completely water resistant and make the
coatings on leaves, skin, feathers, fur, and fruit. They
can be used on floors and furniture for the same
protecting quality.

21. 4. Membrane lipids
1) phospholipids
- phosphoglyceride: phosphatidyl serine (ethanolamine,
choline, inositol)
- sphingolipid: spingosine → sphingomyelin
2) glycolipids
- sugar-containing lipids
- cerebrosides
- gangliosides
3) cholesterol

23. BIOLOGICAL MEMBRANES
O
Triacyl glycerol
HO
HO
CH2
O
C
C
CH2
O
CH2
CH
R1
O
H2 C
OH
OH
HC
CH2
O O
R2
C
H2C
GLYCEROL
O R1
C
CH
C
R2
O
O
O
O
C
R3
TRI ACYL GLYCEROL ( TRIGLYCERIDE)
R3

24. Glycerol phospholipids
O
O
O
O
R
CH2 O O
O
HC
CH2 O
R
R
P
OH
CH2 O O
O
HC
CH2 O
OH
O
O
R
CH2 O O
O
HC
CH2 O
O
CH3
+
N
CH2
P
OH
H3C
R
CH2
CH3
R
OH
NH2
CH2
P
O
CH2

25. O
O
R
CH2 O O
R
O
HC
CH2 O
CH2
P
O
OH
Phosphotidyl serine
NH2
HC
COOH
O
O
R
CH2 O O
R
O
HC
CH2 O
HO
P
O
OH
CH
OH
CH
Phosphotidyl Inositol
CH
CH
CH
CH
HO
OH
OH
O
O
R
CH 2 O O
R
O
HC
HC
P
CH 2 O
HO
OH
OH
O
Phosphatidyl glycerol
CH2
HC
OH
O
O
O
R
R
CH2 O O
O
HC
CH2 O
O
OH
R
HC
P
OH
O
CH2
HC
OH
O O
CH
P
O
CH2
O
HO
Diphosphatidylglycerol (cardiolipin)
CH2
O
R

26. O
O
O
H 2C
H2
C
C
H
O
O
P
H2
C
O
H2
C
NH2
OH
Phosphotidyl Ethanolamine
O
O
O
H2C
C
H
O
O
H2
C
O
CH3
P
H2
C
O
H2
C
OH
O
N
CH3
CH3
Phosphotidyl Choline
O
HO
O
H 2C
O
C
H
OH
O
H2
C
O
O
P
OH
OH
HO
O
OH
Phosphotidyl Inositol
O
O
H2C
O
C
H
NH2
O
H2
C
O
O
P
OH
H2
C
CH
C
O
OH
Phosphotidyl Serine

27. O
R
H2 C
O
R
O
C
H
OH
O
H2
C O
P
H
C
O
OH
H2
C
C
H
OH
OH
O
Phosphotidyl Glycerol
O
O
R
H2 C
R
O
O
C
H
H2
C O
OH
O
P
O
OH
H
C
C
H
H2
C
OH
O
OH
P
O
O
H2
C CH
O
O
CH2
R
O
O
Diphosphotidyl Glycerol
R

28. Ether glycerophospholipids
 Possess an ether linkage instead of an acyl
group at the C-1 position of glycerol
 PAF ( platelet activating factor)
 A potent mediator in inflammation, allergic response
and in shock (also responsible for asthma-like
symptom
 The ether linkage is stable in either acid or base
 Plasmalogens: cis α,β-unsaturated ethers

The alpha/beta unsaturated ether can be hydrolyzed more easily

29. Ether
glycerophospholipids
O
-
O
P
O
H2C
O
CH
O
CH3
O
CH2
CH2
N
-O
CH3
O
CH3
H2C
CH2
H
O
O
CH
O
CH2
CH2
N
CH3
CH2
O
C
C
P
CH3
O
O
H
CH3
A choline plasmalogen
platelet activating factor or PAF
CH3

30. Phospholipase A1
Phospholipase A2
O
O
CH2 O
R
O
HC
CH2 O
O
P
OH
R
O
X
Phospholipase C
Phospholipase D
SURFACTANT ( DIPALMITOYL PHOSPHATIDYL CHOLINE
O
O
CH2 O
PALMITIC
O
HC
CH2 O
O
P
OH
PALMITIC
H3C
N
CH2
O
CH3
+
CH2
CH3

31. SPHINGOLIPIDS
H 3C
SPHINGOMYELIN
CH2
CH2
CH2
CH2
CH2
CH2
CH2 O
CH2
CH2
CH2
CH2
CH2
CH2
CH2
C
Palmitic acid
HO
+
Hydrophobic end
1
CH2
R
CH2
CH2
NH2
H3C
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH
OH
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH
CH2
Sphingosine
OH
O
C
NH
R
CH
CH
HC
CH
O
CH2
O
CH2
P
OH
CH3
OH
+
CH2
N
O
CH3
CH3
CERAMIDE
Hydrophilic end
SPHINGOLIPIDS
H3C
CH2
CH2
CH2
CH2
CH2
CH2
CH2 O
CH2
CH2
CH2
CH2
CH2
CH2
CH2
C
NH
H3C
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH
OH
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH
CH2
Ceramide
Acylated Sphingosine
O
HO
Palmitic acid
+
NH2
OH
Sphingosine
OH
OH
O
NH
R
1
OH
CH2
CH2 O
CH2
C
Ceramide
OH
Acylated Sphingosine
NH
R
CH
CH
HC
OH
CH
CH2
OH
Ceramide
R
O
1
NH
R
OH
OH
Ceramide

32. SPHINGOLIPIDS
O
HO
Palmitic acid
+
NH2
OH
Sphingosine
OH
O
NH
OH
Ceramide
OH
Acylated Sphingosine
R
O
1
R
OH
OH
Ceramide

33. SPHINGOLIPIDS
CEREBROSIDES
Galactocerebroside
R
O
H3C
C
H3C
CH
O
OH
CH 2
O
CH
CH
OH
OH
OH
Glucocerebroside
O
R
1
O
H3C
HN
R
CH2
HC
(CH2) 12
R
HO
NH
C
H3C
CH
CH
CH2
O
CH
OH
OH
OH
OH
HO
CH 2
O
CH
(CH 2) 12
OH
HO
NH
Lactosyl ceramide
R
O
H3C
C
H3C
CH
CH 2
O
CH2
O
CH
(CH 2) 12
HO
NH
CH
CH
OH
OH
OH
HO
O
O
OH
CH2
OH
OH
HO
O
Trihexosyl ceramide
R
H3C
H3C
CH2 NH
C
CH
(CH 2)12
HO
CH
CH2
HO
O
CH
CH
O
OH
CH2
OH
OH
OH
O
O
OH
CH2
O
OH
OH
CH2
OH

34. Some Galactocerebrosides are sulfated at
position 3 of the galactose
CH2
R
1
CH2
CH2
O
HO
C
O
NH
R
CH
CH
O
HC
CH
OH
CH2
H
H
OH
HO
H
H
OSO3H
H

35. GANGLIOSIDES
HO
HO
HO
O
R
NH
H2
C
Cer
(CH2)12
O
O
Glc
OH
OH
O
OH
Gal
OH
GalNAc
O
NANA
NANA
CerGlcGalGalNAcGal
O C
CH3
O
H2
C
Gal
HO
HO
GM3
O
NH
GM1
GM2
OH
CH2
O
CH2
O
CH2
O
HO
OH

36. OH
Globoside Gb3
OH
O
HO
OH
OH
OH O
O
HO
OH
OH
O
O
O
HO
OH
HN
O
OH
OH
O
HO
NH
OH
Globoside Gb4
OH
O
O
OH O
O
O
HO
OH
OH
OH
OH
O
O
HO
O
OH
HN
O

37. THE
UNIVERSAL
BLOOD
GROUP
ANTIGENS
ARE
SPHINGOLIPIDS WHICH ARE EXPRESSED ON THE SURFACE
OF ERYTHROCYTES
Fuc(a1-2)
Gal(B1-4)GalNAc(B) O
Cer
GalNAc(a1-3)
Blood Group A
Fuc(a1-2)
Gal(B1-4)GalNAc(B) O
Cer
Gal(a1-3)
Blood Group B
Fuc(a1-2)
Gal(B1-4)GalNAc(B) O
Blood Group O
Cer

38. 26
21
CH3
18
12
11
2
9
10
3
8
5
4
Polar Head
H
7
CH
16
14
H
HO
17
H
19
1
13
CH3
CH2
CH2
CH2
20
22
23
24
15
HC
25
CH3
27
CHOLESTEROL
6
Non polar Head

39. Steroids

40. Cholesterol, an
important constituent of cell
membranes, has a rigid ring
system and a short branched
hydrocarbon tail.
HO
Cholesterol
Cholesterol is largely
hydrophobic.
But it has one polar group,
a hydroxyl, making it
amphipathic.
PDB 1N83
cholesterol

41. HO
Cholesterol
Cholesterol
in membrane
Cholesterol inserts into bilayer membranes with its
hydroxyl group oriented toward the aqueous phase &
its hydrophobic ring system adjacent to fatty
acid chains of phospholipids.
The OH group of cholesterol forms hydrogen bonds
with polar phospholipid head groups.

42. Interaction with the relatively rigid cholesterol decreases the
mobility of hydrocarbon tails of phospholipids.
Cholesterol
in membrane
But the presence of cholesterol in a phospholipid membrane interferes with close
packing of fatty acid tails in the crystalline state, and thus inhibits transition to the
crystal state.
Phospholipid membranes with a high concentration of cholesterol have a fluidity
intermediate between the liquid crystal and crystal states.

44. OUT
IN

47. peripheral
Membrane proteins may
be classified as:
 peripheral
 integral
 having a lipid anchor
lipid
anchor
lipid bilayer
integral
Membrane
Proteins
Peripheral proteins are on the membrane surface.
They are water-soluble, with mostly hydrophilic surfaces.
Often peripheral proteins can be dislodged by conditions
that disrupt ionic & H-bond interactions, e.g.,
extraction with solutions containing high concentrations
of salts, change of pH, and/or chelators that bind
divalent cations.

48. peripheral
lipid
anchor
lipid bilayer
integral
Membrane
Proteins
Integral proteins have domains that extend into the
hydrocarbon core of the membrane.
Often they span the bilayer.
Intramembrane domains have largely hydrophobic
surfaces, that interact with membrane lipids.

51. lipid
anchor
membrane
cysteine
residue
palmitate
Some proteins bind to membranes via a covalently
attached lipid anchor, that inserts into the bilayer.
A protein may link to the cytosolic surface of the plasma
membrane via a covalently attached fatty acid (e.g.,
palmitate or myristate) or an isoprenoid group.
Palmitate is usually attached via an ester linkage to the
thiol of a cysteine residue.
A protein may be released from plasma membrane to
cytosol via depalmitoylation, hydrolysis of the ester link.

52. CH3
CH3
H3C
C
CH
CH2
CH2
C
CH3
CH
CH2
CH2 C
CH
CH2
Protein
S
farnesyl residue linked to protein via cysteine S
An isoprenoid such as a farnesyl
residue, is attached to some proteins
via a thioether linkage to a cysteine
thiol.
lipid
anchor
membrane

57. Glycosylphosphatidylinositols (GPI) are complex
glycolipids that attach some proteins to the outer surface
of the plasma membrane.
The linkage is similar to the following, although the
oligosaccharide composition may vary:
protein (C-term.) - phosphoethanolamine – mannose - mannose mannose - N-acetylglucosamine – inositol (of PI in membrane)
The protein is tethered some distance out from the
membrane surface by the long oligosaccharide chain.
GPI-linked proteins may be released from the outer
cell surface by phospholipases.

58. Lipid storage diseases




also known as sphingolipidoses
genetically acquired
due to the deficiency or absence of a catabolic enzyme
examples:




Tay Sachs disease
Gaucher’s disease
Niemann-Pick disease
Fabry’s disease
 http://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid

59. What are Lipid Storage Diseases?
Lipid storage diseases are a group of inherited metabolic disorders in
which harmful amounts of fatty materials (called lipids) accumulate in
some of the body’s cells and tissues. Over time, this excessive storage of
fats can cause permanent cellular and tissue damage, particularly in the
brain, peripheral nervous system, liver, spleen, and bone marrow. Lipid
storage diseases are inherited from one or both parents who carry a
defective gene. Symptoms may appear early in life or develop in the
teen or even adult years. Neurological complications of the lipid storage
diseases may include ataxia, eye paralysis, brain degeneration, seizures,
learning problems, spasticity, feeding and swallowing difficulties, slurred
speech, loss of muscle tone, hypersensitivity to touch, burning pain in
the arms and legs, and clouding of the cornea

60. Genetic defects in
ganglioside metabolism
 leads to a buildup of gangliosides
(ganglioside GM2) in nerve cells, killing them
enzyme that hydrolyzes here (beta hexosaminodase)
is absent in Tay-Sachs disease
Gal
NAc Gal Gal Glu
NAcNeu
CER

61. Tay-Sachs disease
 a fatal disease which is due to the deficiency of




hexosaminidase A activity
accumulation of ganglioside GM2 in the brain of
infants
mental retardation, blindness, inability to
swallow
a “cherry red “ spot develops on the macula
(back of the the eyes)
Tay-Sachs children usually die by age 5 and often
sooner

62. Genetic defects in
globoside metabolism
 Fabry’s disease:
 Accumulation of ceramide trihexoside in kidneys of
patients who are deficient in lysosomal αgalactosidase A sometimes referred to as ceramide
trihexosidase
 Skin rash, kidney failure, pains in the lower
extremities
 Now treated with enzyme replacement therapy:
agalsidase beta (Fabrazyme)

63. Genetic defects in
cerebroside metabolism
 Krabbe’s disease:
 Also known as globoid leukodystrophy
 Increased amount of galactocerebroside in the white matter of the
brain
 Caused by a deficiency in the lysosomal enzyme galactocerebrosidase
 Gaucher’s disease:
Caused by a deficiency of lysosomal glucocerebrosidase
Increase content of glucocerebroside in the spleen and liver
Erosion of long bones and pelvis
Enzyme replacement therapy is available for the Type I disease
(Imiglucerase or Cerezyme)
 Also miglustat (Zavesca) – an oral drug which inhibits the enzyme
glucosylceramide synthase, an essential enzyme for the synthesis of
most glycosphingolipids





64. Miglustat (Zavesca)

65. Genetic defects in
ganglioside metabolism
 Metachromatic leukodystrophy
 accumulation of sulfogalactocerebroside (sulfatide) in the
central nervous system of patient having a deficiency of a
specific sulfatase
 mental retardation, nerves stain yellowish-brown with cresyl
violet dye (metachromasia)
 Generalized gangliosidosis
 accumulation of ganglioside GM1
 deficiency of GM1 ganglioside: β-galactosidase
 mental retardation, liver enlargement, skeletal involvement

66. Niemann-Pick disease
 principal storage substance: sphingomyelin
which accumulates in reticuloendothelial cells
 enzyme deficiency: sphingomyelinase
 liver and spleen enlargement, mental
retardation

68. Prostaglandins and other
eicosanoids (prostanoids)
 local hormones, unstable, key mediators of
inflammation
 derivatives of prostanoic acid
9
8
COOH
20
11 12
15
prostanoic acid

69. Prostaglandins

71. O
O
O
R
O
OO
O
P
X
H20
phospholipase A2 (enzyme that hydrolyzes
at the sn-2 position - inhibited
indirectly by corticosteroids)
O
COOH
CH3
COX is inhibibited by
aspirin and other NSAIDs
very unstable
bond
prostaglandin synthase
(also known as cyclooxygenase)
O
COOH
O
PGH2
OH

72. O
COOH
O
OH
PGH2
O
HO
COOH
COOH
HO
OH
PGE2
key mediator of inflammation
HO
OH
PGF2α

73. O
O
O
HO
R1
R1
R1
R1
R2
R2
R2
R2
PGB
PGA
O
R1
O
PGC
PGD
HO
R1
R1
R1
O
O
R2
HO
R2
O
R2
HO
PGE
PGG and PGH
PGFa
R2
HO
PGI
R1
OH
O
R1
R1
R1
O
R2
O
PGJ
R2
O
R2
HO
O
O
PGK
TXA
TXB
SUBSTITUTION PATTERN OF PROSTANOIDS
R2

74. Prostacyclins, thromboxanes
and leukotrienes
 PGH2 in platelets is converted to thromboxane A2
(TXA2) a vasoconstrictor which also promotes
platelet aggregation
 PGH2 in vascular endothelial cells is converted to
PGI2, a vasodilator which inhibits platelet
aggregation
 Aspirin’s irreversible inhibition of platelet COX
leads to its anticoagulant effect

75. Functions of eicosanoids
 Prostaglandins – particularly PGE1 – block gastric
production and thus are gastric protection
agents
 Misoprostol (Cytotec) is a stable PGE1 analog that
is used to prevent ulceration by long term NSAID
treatment
 PGE1 also has vasodilator effects
 Alprostadil (PGE1) – used to treat infants with
congenital heart defects
 Also used in impotance (Muse)

76. Functions of eicosanoids
 PGF2α – causes constriction of the uterus
 Carboprost; “Hebamate” (15-Me-PGF2α) – induces
abortions
 PGE2 is applied locally to help induce labor at
term

77. Leukotrienes
Non-peptidoleuktrienes: LTA4 is formed by dehydration of
5-HPETE, and LTB4 by hydrolysis of the epoxide of LTA4
O
COOH
C5H11
HO
COOH
LEUKOTRIENE A4 (LTA4)
C5H11
OH
LEKOTRIENE B4 (LTB4)

79. Biological activities of
leukotrienes
1. LTB4
2. LTC4
3. LTD4
4. LTE4
- potent chemoattractent
- mediator of hyperalgesia
- growth factor for keratinocytes
- constricts lung smooth muscle
- promotes capillary leakage
1000 X histamine
- constricts smooth muscle; lung
- airway hyperactivity
- vasoconstriction
- 1000 x less potent than LTD4
(except in asthmatics)

80. Leukotrienes
Leukotrienes are derived from arachidonic acid via the enzyme
5-lipoxygenase which converts arachidonic acid to 5-HPETE
(5-hydroperoxyeicosatetranoic acid) and subsequently by
dehydration to LTA4
OH
OH
COOH
COOH
H
C5H11
H
S
Cys
gGlu
LEUKOTRIENE F4 (LTF4)
peptidoleukotrienes
C5H11
S
Cys
Gly
gGlu
LEUKOTRIENE C4 (LTC4)

81. Leukotrienes
Leukotrienes are synthesized in neutrophils, monocytes, macrophages,
mast cells and keratinocytes. Also in lung, spleen, brain and heart.
A mixture of LTC4, LTD4 and LTE4 was previously known as the
slow-reacting substance of anaphylaxis
OH
OH
COOH
COOH
H
C5H11
H
S
Cys
LEUKOTRIENE E4 (LTE4)
peptidoleukotrienes
C5H11
S
Cys
Gly
LEUKOTRIENE D4 (LTD4)