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LIPIDS
Introduction
Definition: water insoluble compounds• Most lipids are fatty acids or esters of fatty
acids• They are soluble in non-polar solvents such
as petroleum ether, benzene, chloroform
1. Store energy: fat cells
2. Chemical messengers: find in nerve fibers and hormones.
3. Parts of membranes: insoluble in water
Lipids
4. Precursors of hormones (steroids
and prostaglandins)
Functions
Thermal blanket
LipidsThere are 2 types of lipids; •those that contain the structural component of a fatty acid; and
•those that contain the structural component of a four member steroid molecule.
Lipids
1. Simple lipids:
Triglycerides (Fats & Oils), Waxes
2. Complex lipids Glycerophospholipids
Steroids (Cholesterol & steroid hormones)
3. Eicosanoids
Store energy, insulation
Cell
membrane
Chemical messenger
Cell membrane
Pain, fever, inflammation
Sphingolipids
Lipids with fatty acids
Lipids without fatty acids
Properties of fats and oils
• fats are solids or semi solids
• oils are liquids
• melting points and boiling points are not usually sharp (most fats/oils are mixtures)
• when shaken with water, oils tend to emulsify
• pure fats and oils are colorless and odorless
(color and odor is always a result of contaminants) –i.e. butter (bacteria give flavor, carotene gives color)
Lipids can be categorized as:
1. Hydrolyzable lipids can be converted into small
molecules by aqueous hydrolysis.
Lipids
Lipids can be categorized as:
2. Nonhydrolyzable lipids cannot be cleaved into smaller
molecules by aqueous hydrolysis.
Lipids
Hydrolysis: reaction with water.
(breaking a bond and adding the elements of water)
RCOR'
O
RC-OH
O
H-OR'
An alcoholA carboxylic acidAn ester
+ H2O +Heat
H+ or enzyme
Hydrolysis
Most hydrolyzable lipids contain an ester.
Fatty acids
• Fatty acids can be classified either as:➢saturated (C-C bonds) or unsaturated (also C=C)
➢according to chain length:• short chain FA: 2-4 carbon atoms
• medium chain FA: 6 –10 carbon atoms
• long chain FA: 12 – 26 carbon atoms
➢ essential fatty acids vs those that can be biosynthesized in the body:
– linoleic and linolenic are two examples of essential fatty acid
– oleic, stearic – nonessential
Fatty acids
• Carboxylic acid are derivatives of long chain hydrocarbons
– Nomenclature
• Stearate – stearic acid – C18:0 – n-octadecanoic acid
– General structure of saturated fatty acids:
Cn H2n+1 COOHn - carbon atoms in a molecule
COOH
COOH
COOH
COOH
Stearic acid (18:0)
(mp 70°C)
Oleic acid (18;1)
(mp 16°C)
Linoleic acid (18:2)
(mp-5°C)
Linolenic acid (18:3)
(mp -11°C)
Nomenclature of fatty acids
SATURATED FATTY ACIDS
Common name Systematic name Formula
C4:0 Butyric Butanoic acid C3H7COOH
C6:0 Caproic acid Hexanoic acid C5H11COOH
C8:0 Caprylic acid Octanoic acid C7H15COOH
C10:0 Capric acid Decanoic acid C9H19COOH
C12:0 Lauric acid Dodecanoic acid C11H23COOH
C14:0 Myristic acid Tetradecanoic acid C13H27COOH
C16:0 Palmitic acid Hexadecanoic acid C15H31COOH
C18:0 Stearic acid Octadecanoic acid C17H35COOH
C20:0 Arachidic Eicosanoic acid C19H39COOH
C24:0 Lignoceric acid Tetracosanoic acid C23H47COOH
C16:0 Palmitic acid (C15H31COOH)
Structural formula of palmitic acid
CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 COOH
CH3(CH2)14COOH
Condensed structural formula of palmitic acid
Skeletal formula of palmitic acid
C
O
OH
Fatty acids
Fatty acids are:
• Long-chain unbranched carbon
attached to a carboxyl group (-COOH).
• Typically 12-20 carbon atoms.
• They have an even number of C atoms.
• Insoluble in water.
COOH
COOH
COOH
COOH
Stearic acid (18:0)
(mp 70°C)
Oleic acid (18;1)
(mp 16°C)
Linoleic acid (18:2)
(mp-5°C)
Linolenic acid (18:3)
(mp -11°C)
COOH
COOH
COOH
COOH
Stearic acid (18:0)
(mp 70°C)
Oleic acid (18;1)
(mp 16°C)
Linoleic acid (18:2)
(mp-5°C)
Linolenic acid (18:3)
(mp -11°C)
Cis
Hydrolyzable lipids are derived from fatty acids.
Fatty acids
nonpolar portion = hydrophobic
polar portion = hydrophillic
CH3(CH2)14COOH (palmitic acid)
Hydrophobic portion is much bigger than hydrophilic portion.
Insoluble in water
Saturated and unsaturated Fatty acids
Saturated fatty acids have no double bonds in their long hydrocarbon
chains.
COOH
COOH
COOH
COOH
COOH
Packed together
They are solids at room temperature.
Stearic acid: CH3(CH2)16COOH
Unsaturated fatty acids have 1 or more double bonds (generally cis) in their
long hydrocarbon chains.
Saturated and unsaturated Fatty acids
COOH
COOH
COOH
COOH
COOH
They can not pack together
They are liquids at room temperature.
Oleic acid: CH3(CH2)7CH=CH(CH2)7COOH
Kinks
Unsaturated fatty acids
• Various conventions are in use for indicating the number and position of the double bond(s)
HC CH(CH2)7COOH(CH2)7H3C
1918
10
18:1,9 or 9 18:1
H3C CH2CH2CH2CH2CH2CH2CH2CH CH(CH2)7COOH
191017n
2 3 4 5 6 7 8 9 10 18
9, C18:1 or n-9, 18:1
In chemistry
n (Δ) designation:
In biochemistry:
ω designation
Carbon atom numbering starts from COOH group
Carbon atom numbering starts from CH3 group
ω = omega
Δ = delta
• The human body is capable of synthesizing most fatty acids
from carbohydrates or other fatty acids.
• Humans do not synthesize sufficient amounts of fatty acids
that have more than one double bond.
• More than one double bond fatty acids are called essential
fatty acids and they must be provided by the diet.
Fatty acids
Linoleic acid Linolenic acid
(Omega 6)Fatty acids that contain at least two double bonds, one of them at C6 (carbon atom numbering starts from CH3 group).
LINOLEIC ACID 18:2 (9,12) is main representative acid of this group
(Omega 3)Fatty acids that contain at least two double bonds, one of them at C3 (starting from CH3 group)
LINOLENIC ACID 18:3 (9,12,15) is the basic acid of this group
The Essential Fatty Acids (EFA) are a group of fatty acids that are essential to human
health
CH7
CH2
CH CH
(CH2)7 COOH18
CH6
CH25
CH4
CH3
CH22
CH31
CH7
CH28
CH9
CH10
(CH2)7 COOH18
CH6
(CH2)4CH31
Linoleic acid is called an omega-6 acid, because of the
position of the first C=C in the nonpolar chain.
Essential Fatty acids
Omega-n acids n: the position of the first double bond
carbon atom numbering startsfrom CH3 group
Linolenic acid is called an omega-3 acid, because of the
position of the first C=C in the nonpolar chain.
Essential Fatty acids
Omega-3 sources:Flaxeed oil/canola oil
Fish liver oils/Fish eggs
Human Milk
Seafood/Fatty fish
- albacore tuna
- mackerel
- salmon
-sardines
Omega-6 sources:Corn oil
Peanut oil
Cottonseed oil
Soybean oil
Many plant oils
➢Proper n-6 to n-3 ratio in a diet is 4:1
Fatty acids
• Common medium-chain saturated fatty acids:
C5H11COOH caproic acid (hexanoic acid)
C7H15COOH caprylic acid (octanoic acid)
C9H19COOH capric acid (decanoic acid)
CH36
CH25
CH24
CH23
CH22
COOH1 caproic acid
➢ liquid (C1 to C6), solid (from C7)
• C3H7COOH butyric acid (butanoic acid) – short chain FA
Fatty acids
• common long-chain saturated FA’s:
C11H23COOH : lauric acid (n-dodecanoic acid; C12:0)
C13H27COOH : myristic acid (n-tetradecanoic acid; C14:0)
C15H31COOH : palmitic acid (n-hexadecanoic acid; C16:0)
C17H35COOH; stearic acid (n-octadecanoic acid; C18:0)
C19H39COOH; arachidic (eicosanoic acid; C20:0)
C23H47COOH; lignoceric acid
C25H51COOH; cerotic acid
Less common fatty acids
• iso – isobutyric acid
• odd carbon fatty acid – propionic acid
• hydroxy fatty acids – ricinoleic acid, dihydroxystearicacid, cerebronic acid (found in higher plants)
• cyclic fatty acids – hydnocarpic, chaulmoogric acid(nonedible fat and oil isolated from chaulmoogra oil, used in LEPROSY treatment)
R
H3C
H3C H3C
R
CH3
(CH2)12-CO2H (CH2)10-CO2H
chaulmoogric acid hydnocarpic acid
R= COOH
MonoUnsaturated fatty acidsMUFA
• Monoenoic acid (monounsaturated) Cn H2n-1 COOH
There is free rotation about C-C bonds in the fatty acid hydrocarbon, except where there is a double bond.
• C18H34O2
• C17H33 COOH
Double bond is always
cis in natural fatty acids.
COOH
Elaidic acid
18:1 (9trans)
C10
C9
CH211
CH28
(CH2)6CH318
(CH2)6 COOH1
H H
Oleic acid 18:1 n-9(cis) or 18:1 (Δ9)
Chemical formula
Unsaturated fatty acids
• Dienoic acid: linoleic acid 18:2 (9cis, 12cis)
(CH2)4CH3 CH=CH CH2 CH=CH (CH2)7 COOH
cis
linoleic acid
Trienoic acid: linolenic acid 18:3 (9cis, 12cis, 15cis)
Chemical formula
C18H32O2
C17H31COOH
PolyUnsaturated fatty acidsPUFAs
• Polyenoic acid (polyunsaturated, tetranoic acid)
COOH
CH3
Arachidonic acid 20:4 (Δ 5,8,11,14)
PUFAs are fatty acids that contain more than one double bond in their backbone
CH3-(CH
2)7-CH=CH-(CH
2)7-COOH
UNSATURATED FATTY ACIDS
Oleic acid 18:1 ω-9 cis Δ9
Elaidic acid 18:1 ω-9 trans Δ9
Linoleic acid (LA) 18:2 ω-6 cis Δ 9,12
γ-Linolenic acid (GLA) 18:3 ω-6 cis Δ6,9,12
α-Linolenic (ALA) 18:3 ω-3 cis Δ 9,12,15
Arachidonic acid 20:4 ω-6 cis Δ 5,8,11,14
Eicosapentaenoic acid (EPA) 20:5 ω−3 cis Δ 5,8,11,14,17
Docosahexaenoic acid (DHA) 22:6 ω−3 cis Δ 4,7,10,13,16,19
COOH18 9
COOH
18
9
CH3-(CH
2)7-CH=CH-(CH
2)7-COOH
COOH9
18
12 CH3-(CH
2)4-(CH=CH-CH
2)2-(CH
2)6-COOH
COOH
9
18
12 6 CH3-(CH
2)4-(CH=CH-CH
2)3-(CH
2)3-COOH
COOH18 9
CH3-CH
2-(CH=CH-CH
2)3-(CH
2)6-COOH
COOH8
20
11 514 CH3-(CH
2)4-(CH=CH-CH
2)4-(CH
2)2-COOH
COOH820 11 51417 CH
3-CH
2-(CH=CH-CH
2)5-(CH
2)2-COOH
4
COOH
19 101316 722 CH3-CH
2-(CH=CH-CH
2)6-CH
2-COOH
Comparison of melting points
Melting Points of Saturated vs. Unsaturated Fatty Acids:
the unsaturated fatty acids have lower melting points than the
saturated fatty acids.
The molecular structure allows many fatty acid molecules to be rather closely "stacked" together. Close intermolecular interactions result in relatively high melting points.
The introduction of one or more doublebonds in the hydrocarbon chain inunsaturated fatty acids results in one ormore "bends" in the molecule. Thesemolecules do not "stack" very well. Theintermolecular interactions are muchweaker than saturated molecules. As aresult, the melting points are much lowerfor unsaturated fatty acids.
Comparison of melting pointsMelting Points of Saturated vs. Unsaturated Fatty Acids:
the unsaturated fatty acids have lower melting points than the
saturated fatty acids.
COOH
COOH
COOH
18:0 18: 1 18:3
Melt.p. 70oC 16oC -11oC
Comparison of melting points
Saturated FA (highest melting point)
Unsaturated trans (intermediate m.p.)
Unsaturated cis (lowest m.p.)
Function of EFAs
• Formation of healthy cell membranes
• Proper development and functioning of the brain and nervous system
• Production of hormone-like substances called Eicosanoids –Thromboxanes
–Leukotrienes
–Prostaglandins
They are responsible for regulating blood pressure, blood viscosity, immune and inflammatory responses.
Long-chain alcohol Fatty acidEster bond
Waxes
Wax is an ester of saturated fatty acid and long chain alcohol.
Acid
Long-chain alcohol
Because of their long nonpolar C chains, waxes are very hydrophobic.
Waxes
Beeswax(myricyl palmitate)
CH3(CH2)14 C
O
O(CH2)29CH3
hydrophobic
regionhydrophobic
region
They form protective coatings:
- In plants, they help prevent loss of water and damage from pests.
- In humans and animals, provide waterproof coating on skin and fur.
Beeswax CarnaubaCoating
Jojoba
Lanolin from wool lotions
Waxes
Hydrolysis reaction: like other esters, waxes are hydrolyzed.
Heat
Sodium soaps1,2,3-Propanetriol
(Glycerol; glycerin)A triglyceride
( a triester of glycerol)
+saponification
+
CH2 OCR
CH2 OCR
CHOH
CH2 OH
CH2 OH
RCOCH 3 NaOH 3 RCO-Na
+O
O
O
O
Soaps
Hydrophobic part: nonpolar
Hydrophilic part: polar (remains in contact with environment)
a soap is
a salt of
a fatty acid
Soaps
++
+
+
+ +
+
+
+
+ +
+
Na+
fat
waterO
HH
Soaps solution
- a micelle
(emulsion type o/w)
Organization of soaps
molecules in water
When soap is mixed with dirt (grease, oil, and …), soap
micelles “dissolve” these nonpolar, water-insoluble molecules.
Soaps
soft
-potassium soaps, e.g shampoo,
shaving soaps, liquid soaps
C17H35COO-K+
Soaps
hard
-sodium soaps
e.g. soap bar
C17H35COO-Na+
water insoluble-barium, magnesium, calcium soaps
(C15H31COO)2Ba
Soaps don’t work effectively
in hard water!
Amphipatic (amphiphilic)
nature of a soap
water soluble
polar hydrophilic
carboxylate group COO-
nonpolar hydrophobic
hydrocarbon chain
e.g. stearate C17H35-
Detergents➢ Synthesis of detergents
(CH2)n-CH3
n=10-20
H2SO
4
OSO2H
(CH2)n-CH3NaOH
OSO2 Na+
(CH2)n-CH3
_
alkylbenzene alkylbenzenesulfonic acid sodium salt
of alkylbenzenesulfonic acid
➢ Detergents work effectively in hard water –
their barium or magnesium salts are water
soluble
These substances are usually alkylbenzenesulfonates
Polar sulfonate (of detergents) is less likely than the
polar carboxylate (of soap) to bind to calcium and other ions found
in hard water.
Simple lipids
• Glycerides (fats and oils)– Glycerol
– Esters of glycerol - monoglycerides, diglycerides and triglycerides
• Waxes – simple esters of long chain alcohols and long chainfatty acids
C OHH
CH2OH
CH2OH
glycerol
GLYCERIDES
Function: storage of energy in compact form and cushioning
CH2
C
CH2
O
OH
OH
H
C
O
(CH2)14 CH3
*
CH2
C
CH2
OH H
O C
O
O C
O
(CH2)14 CH3
(CH2)14 CH3
CH2
C
CH2
O H
O C
O
OH
C
O
(CH2)16
(CH2)7CH CH (CH2)7 CH3
CH3*
CH2
C
CH2
O H
O C
O
O C
O
(CH2)14 CH3
(CH2)14 CH3
C
O
(CH2)14CH3
1-palmitomonoglyceride
1-oleo-2-stearodiglyceride
Triglyceride (tripalmitin)
1,3-dipalmitodiglyceride
Triglycerides
1-stearoyl-2,3 linoleoyl glyceride
Triglycerides chemical properties
➢Acidic hydrolysis (reaction reversible)
➢ Basic hydrolysis (SAPONIFICATION, reaction irreversible)
+ +3H2O
CH2
CH
CH2 O H
O H
O HCH2
CH
CH2 O C
O C
O C
O
R1
O
R2
O
R3
C R1
HO
O
C R2
HO
O
C R3
HO
O
H+
Triglyceride fatty acids glycerol
+ +3NaOH
CH2
CH
CH2 O H
O H
O HCH2
CH
CH2 O C
O C
O C
O
R1
O
R2
O
R3CR3
ONa
O
CR1
ONa
O
CR2
ONa
O
Triglyceride salts of fatty acids glycerol
(soaps)
➢ Enzymatic hydrolysis (reaction reversible) – a STEREOSELECTIVE reaction
Fatty acids of
carbons C1 i C3
+
CH2
CH
CH2 O H
O C
O H
O
R2
CH2
CH
CH2 O C
O C
O C
O
R1
O
R2
O
R3
CR3
OH
O
CR1
OH
O lipase
+ 2H2O
Triglycerides chemical properties
Triglyceride 2-monoglyceride
After ca. 5 minutes isomerization of a fatty acid group from C2
to C1 position occurs.
Afterwards hydrolysis of the last FA group happens.
➢ Hardening (hydrogenation)
Triolein Tristearin
(liquid plant fat) (solid fat: margarine)
The fastest hydrogenation occurs at position C-1 and C-3 and for
fatty acids rests containing four-three double bonds
Negative side effects: trans fatty acids obtaining, changing of double
bond positions, polimerization of double bonds
CH2
C
CH2
O H
O C
O
O
C
O
(CH2)7
(CH2)7 CH
CH
C
O
CH
(CH2)7CH3
CH
(CH2)7
CH3
(CH2)7 CH CH
(H2C)7 CH3
CH2
C
CH2
O H
O C
O
O
C
O
(CH2)16
(CH2)16 CH3
C
O
(CH2)16 CH3
CH3
Ni+ 3H2
Triglycerides chemical properties
+NaOH
CH2
CH
CH2 O C
O C
O C
O
C15H31O
C17H33
O
C15H31
CH2
CH
CH2 O C
O C
O C
O
C17H35O
C17H33
OC17H29
+
CH2
CH
CH2 O C
O C
O C
O
C15H31O
C17H33
O
C17H29
CH2
CH
CH2 O C
O C
O C
O
C17H35O
C17H33
O
C15H31
substitute of cocoa butter
Triglycerides chemical properties
➢Transesterification – to make fats more nutritious and healthy, to introduce
omega-3 and omega-6 fatty acids to the structure of edible fats.
➢ No unfavourable side effects during synthesis.
➢It is the source of structured fats.
CH2
CH
CH2
O
O
O
O
O
O
SHORT/MEDIUM CHAIN FATTY ACID
OMEGA-3 or -6 FATTY ACID
SHORT/MEDIUM CHAIN FATTY ACID
1-stearo-2-oleo-3-palmitin
Types of Fatty Acid Lipids
Phospholipids
phospate phospate
Phospholipids
Phospholipids are lipids that contain a P atom.
Two common types:
They are the main component of most cell membranes.
Structurally, they resemble a triacylglycerol, except the third fatty
acid has been replaced with a phosphodiester bonded to an
alcohol.
Phospholipids
Amino alcohol
Fatty acid
Fatty acid
1. Phosphoacylglycerols (glycerophospholipids):
Phospholipids - main components
Phosphoric acid
CH2 OH
C H
CH2 OH
HO
Glycerol
P
O
OH
OH
OH
➢ Hydroxyl compounds:
choline
inosytol
CH2 CH
NH2
COOHOH
OHOH
OH
OH
OHOH
CH2 CH2 NH3OH+
CH2 CH2 N+
HO
CH3
CH3CH3
ethanolamine
serine
1. Phosphoacylglycerols:
Phospholipids
CholineEthanolamine
Phosphatidylserine (cephaline)
Phosphatidylethanolamine (cephaline)
Phosphatidylcholine (lecithine)
Ester bond
CH2 CH
NH2
COOH
CH2 CH2 N+
CH3
CH3CH3
CH2 CH2 NH3
+
CH2
C
O
O
CH2 O
H
P
O
O
OH
C
O
C15H31
C
O
C17H35
R
*
Phospholipids
Their names depending on R:
1. Phosphoacylglycerols:
- phosphatidylcholine (-lecithine)
-phosphatidylethanolamine
(- cephaline)
*
CH2
C
O
O
CH2 O
HC
O
C17H35
C
O
C15H31
P
O
O
OH
CH2 CH2 N(CH3)3
+
Natural phospholipids are L i .
*
CH2
C
O
O
CH2 O
H
C
O
C15H31
P
O
O
C
O
C15H31
OH
CH2CH2H3N+
hydrophilic hydrophobic
Phospholipids
ester bond
phosphoester bond
1. Phosphoacylglycerols:
2 Plasmalogens
- form 10% of brain and muscles phospholipids
ethanolamine
Ether bond
Ethanolamine plasmalogen
R1 – rest of an alcohol
(mainly unsaturated)
R – rest of fatty acids*
C
C
O
O
CH2 O
H
P
O
O
OH
C
O
R
CH2 CH2 NH3
C CH R1
H
H
H
+
Phospholipids
They have anticancer properties.
Ethalomine
Serine
Choline
Inositol
Phospholipids
3. Sphingolipids (Sphingomyelins): They differ in two ways:
1. They do not contain a glycerol backbone, they have a
sphingosine backbone instead.
sphingosine
2. They do not contain an ester; their single fatty acid is bonded to
the backbone by an amide bond.
Phospholipids
3. Sphingolipids (Sphingomyelins)
The myelin sheath, the coating that surrounds nerve cells, is rich in
sphingomyelins.
CH3(CH2)12
C CCH CH
NH2
OH
CH2 OHH
H CH3(CH2)12
C CCH CH
NH
OH
CH2 OHH
H C
O
R
-forms the myeline sheath around the axon of a neuron. It is essential for
the proper functioning of the nervous system.
Sphingosine Ceramide
Sphingomieline
Amide bond
Ester bond
R – rests of fatty acids
CH3(CH2)12
C CCH CH
NH
OH
CH2 OH
H C
O
R
P
O
OH
O R1
R1 – rests of
choline, serine,
ethanolamine
Phospholipids
3. Sphingolipids (Sphingomyelins)
Phospholipids
Sphingomieline
3. Sphingolipids (Sphingomyelins)
Glycolipids
CH3(CH2)12
C CCH CH
NH
OH
CH2O
H
H C
O
(CH2)OH (CH2)21 CH3
C O
C
CC
C
H
HH
H
OH
OH
H OH
CH2 OH
Sugar, e.g. gluctose
Fatty acid,
e.g. Cerebronic acid
sphingosine
➢ Cerebrosides - is a sphingolipid (ceramide) with a monosaccharide such as
glucose or galactose as polar head group.
➢ gangliosides – a polar head group that is a
complex oligosaccharide.
Cerebrosides and gangliosides, collectively called
glycosphingolipids, are commonly found in the
outer leaflet of the plasma membrane bilayer, with
their sugar chains extending out from the cell
surface.
Component Structures of Some Important Membrane Lipids
Prostaglandins-prostanoids (eicosanoids)
A prostaglandin is any member of a group of lipid compounds that
are derived enzymatically from fatty acids.
Every prostaglandin contains 20 carbon atoms, including a 5-carbon
ring.
They are local hormones and have a wide variety of actions:
- cause constriction or dilation in vascular smooth muscle cells
- cause aggregation or disaggregation of platelets
- sensitize spinal neurons to pain
- decrease intraocular pressure
- regulate inflammatory mediation
- regulate calcium movement
- control hormone regulation
- control cell growth
8
12 20
COOH1
Prostanoic acid
Linoleic acid (18:2)
COOH1
58
11 1420
COOH1
5
68
10
12 14
20
OH
OH
O
O 13
5 COOH1
15
20
OH
COOH16
11
9
13 15
20
O
O
OHOH
11
9
13 15
20
OH
OHOH
5 COOH1
PGH2
Arachidonic acid(20:4)
LTB4 (leukotriene)
6-keto-PGF1
(prostacyclin)
PGF2 (prostaglandin)
TXB2 (thromboxane)
14 16
21
OH
5 COOH1
O
11
9
OH
OH
acyclic compound
Cyclic compounds
Prostaglandins-prostanoids (eicosanoids)
CYCLOOXYGENASE aspirine inhibits it
Prostaglandins and Leukotrienes are two types of
eicosanoids (20 C atoms derived from the fatty acids).
Eicosanoids
- All eicosanoids are very potent compounds, which are not
stored in cells, but rather synthesized in response to external
stimulus.
- Unlike hormones they are local mediators, performing their
function in the environment in which they are synthesized.
Prostaglandins
Prostaglandins are responsible for inflammation.
- Aspirin and ibuprofen relieve pain and inflammation by blocking
the synthesis of these molecules.
- Prostaglandins also decrease gastric secretions, inhibit blood
platelet aggregation, stimulate uterine contractions, and relax
smooth muscles.
- There are two different cylcooxygenase enzymes
responsible for prostaglandin synthesis called COX-1 and
COX-2.
Prostaglandins
COX-1 is involved in the usual production of
prostaglandins.
COX-2 is responsible for additional prostaglandins in
inflammatory diseases like arthritis.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and
ibuprofen inactivate both COX-1 and -2, but increase risk for
stomach ulcer formation.
- Drugs sold as Vioxx, Bextra, and Celebrex block only the
COX-2 enzyme without affecting gastric secretions.
Leukotrienes are molecules that contribute to the asthmatic
response by constricting smooth muscle of the lung.
Asthma is characterized by chronic inflammation, so inhaled
steroids to reduce this inflammation are commonly used.
New asthma drugs act by blocking the synthesis of
leukotriene C4, which treat the disease instead of just the
inflammation symptoms.
Leukotrienes
Steroids have:
• A steroid nucleus which is
4 carbon rings.
• Attached groups that make the different types of compounds.
• No fatty acids.
Steroids
(steroid nucleus)
Steroids ➢ the group of naturally occuing compounds (plants, animals,
microorganisms)
All of them possess the 4-ring skeleton of STERAN (1,2-cyclopentano-
perhydrofenantrene).
10
5
1
4
2
3
8
7
9
6
13
14
12
1117
16
15
A B
C D
Steroids differ in: mutual arrangement of condensed rings– A/B, B/C and C/D,
degree of unsaturation, and type and length of side chains R1, R2 and R3.
Steran
➢ sterols –steroids contaning -OH group in the C3 position
10
5
1
4
2
3
8
7
9
6
13
14
12
1117
16
15
R1
R2
R3
A B
C D
Common steroids’ skeleton
R1, R2 – mainly
CH3 groups
R3 – hydrocarbon
chain of different
length
Cholesterol and cholesterol esters
The hydroxyl at C-3 is hydrophilic; the rest of the
molecule is hydrophobic (amphipatic molecule);
also 8 centers of asymmetry
10
53
6
1317
CH3
CH3
CH2
CH2CH3
CH2
CHCH3
CH3
OH
xx
x
x
x
x
x
x
CH3
CH3
CH3CH2CH3
CH3 CH3
OH
CH3
CH3
CH3CH3
CH3 CH3
OH-Sitosterol(phytosterol, in plants)
(to progesteron production)
Ergosterol, in fungi
(to vit. D2 production)
Functions:
-serves as a component of cell membranes (moderates
membrane fluidity)
-precursor to steroid hormones
-storage and transport – as cholesterol palmitate esters or
esters with linolenic acid
Cholesterol sources, biosynthesis and degradation
• diet: only found in animal fat
• biosynthesis: primarily synthesized in the liver from acetyl-coA; biosynthesis is inhibited by LDL (low density lipoprotein) uptake
• degradation: only occurs in the liver
Cholesterol:
• Is the most abundant steroid in the body.
• Insoluble in water (need a water soluble carrier).
• Has methyl CH3- groups, alkyl chain, and -OH
attached to the steroid nucleus.
CH3
CH3CH3
CH3
HO
CH3
Cholesterol
Triacylglycerols
Lipoproteins
Transporting lipids through the bloodstream to tissues where they are stored,
Used for energy, or to make hormones.
Spherical particles
Polar surface and nonpolar inner
Water-soluble form of lipids
(soluble in blood)
Lipoproteins
VLDL: very-low-density lipoprotein
LiverFat storage
cells
Heart and
muscles
LDL
VLDL
HDLEnergyIntestine
and
elimination
Triglycerides and Cholesterol
LDL: low-density lipoprotein (bad Cholesterol) Cholesterol
Chylomicrons Triglycerides and Cholesterol
HDL: high-density lipoprotein (good Cholesterol) Cholesterol
Recommended levels are: HDL > 40 mg/dL, LDL < 100 mg/dL, total serum cholesterol < 200 mg/dL.
1. Sex hormones
2. Adrenal Cortical Steroids
Steroid Hormones
A hormone is a molecule that is synthesized in one part of an
organism, which then elicits a response at a different site.
Two types of steroids hormones:
Estrogens & progestins in females
Androgens in males
Sex Hormones
The estrogens estradiol and estrone control development of secondary
sex characteristics, regulate the menstrual cycle, and are made in the
ovaries.
Estrogens (Female Sex Hormones):
Sex Hormones
Progestins (Female Sex Hormones):
The progestin progesterone is called the “pregnancy hormone”; it is
responsible for the preparation of the uterus for implantation of a fertilized
egg.
Sex Hormones
Androgens (Male Sex Hormones):
Testosterone and Androsterone are androgens made in the testes.
They control the development of secondary sex characteristics in males.
Adrenal Cortical Steroids
Aldosterone regulates blood pressure and volume by controlling the
concentration of Na+ and K+ in body fluids.
Cortisone and cortisol serve as anti-inflammatory agents, which also
regulate carbohydrate metabolism.
aldosteronecortisone
cortisol
They are organic compounds required in small quantities for normal
metabolism.
Vitamins are either water soluble or fat soluble.
The four fat-soluble vitamins (A, D, E, and K) are lipids and
nonpolar.
Excess vitamins are stored in adipose cells to be used when needed.
Vitamins
They must be obtained from the diet (our cells cannot synthesize them).
They are found in fruits, vegetables, fish, liver, and dairy products.
Vitamins
It is found in liver, fish, and dairy products, and is made from β-carotene
(the orange pigment in carrots).
It is needed for vision and for healthy mucous membranes.
Vitamin A deficiency causes night blindness and dry eyes and skin.
Vitamin A
Vitamins
Vitamin D
Vitamin D can be synthesized from cholesterol. It is produced
in the skin on exposure to UV radiation
It can be obtained in the diet from many foods, especially milk, and
helps regulate Ca and P metabolism.
Is necessary for normal bone growth and function.
A deficiency of vitamin D causes rickets (bone malformation).
Vitamins
Vitamin E
Vitamin E is an antioxidant, protecting unsaturated side chains in
fatty acids from unwanted oxidation.
Deficiency of vitamin E causes numerous neurological problems,
although it is rare.
Vitamin K
Vitamin K regulates the synthesis of clotting proteins (prothrombin),
and deficiency of this leads to excessive or fatal bleeding.
Vitamins
Schematic Diagram of a Cell Membrane
The phospholipid bilayer with embedded cholesterol and protein
molecules.
Short oligosaccharide chains are attached to the outer surface.
Lipid bilayer
➢ Main components of lipid bilayer are: phospholipids, glycosphingolipids
and cholesterol (all lipids from 20 to 75%), proteins (ca. 50%), carbohydrates
➢ The bilayer has LIQUID-CRYSTAL CHARACTER
➢ In the liquid crystal state, hydrocarbon chains of
phospholipids are disordered and in constant motion
➢At lower temperature, a membrane containing a single
phospholipid type undergoes transition to a crystalline state
in which fatty acid tails are fully extended, packing is highly
ordered
Extracellular
matrixGlycoprotein
Carbohydrate
Plasma
membrane
Microfilaments
of cytoskeleton
Phospholipid
Cholesterol
Proteins
Cytoplasm
Glycolipid
Lipid bilayer
➢ Cholesterol inserts into bilayer membranes with its hydroxyl group oriented toward the aqueous phase and its hydrophobic ring system is very close to fatty acid chains of phospholipids
➢ Cholesterol regulates bilayer fluidity - interaction with the relatively rigid
cholesterol decreases the mobility of hydrocarbon tails of phospholipids
➢ In the absence of cholesterol, such membranes would crystallize at
physiological temperatures
Saponification number• the highest mass of a triglyceride, the lowest saponification
number• defined as the number of milligrams of KOH needed to neutralize the
fatty acids in 1 gram of fat
• butter (large proportion of short chain FAs) sap. no. 220 – 230
• oleomargarine (long chain FAs) sap. No is 195 or less
CH2
C
CH2
O H
O C
O
O C
O
C15H31
C15H31
C
O
H31C15+
CH2
CH
CH2 O H
O H
O H
CH31C15
O
O
K
CH31C15
O
O
K
CH31C15
O
O
K+ 3 KOH
806 g tripalmitin - 3 . 56 g KOH
1 g - x
x = 0,208 g = 208,4 mg
Iodine number• measures the degree of unsaturation in a given amount of fat or oil
• the iodine number is the number of grams of iodine absorbed by 100 grams of fat
• Cottonseed oil: 103 –111
• Olive oil: 79 – 88
• Linseed oil: 175 –202
• frequently used to determine adulteration of commercial lots of oils (older fats have lower iodine numbers)
+
CH2
C
CH2
O H
O C
O
O
C
O
(CH2)7 CH CH
(CH2)7
CH3
(CH2)7
CHCH
CH2
CHCH
CH2
CHCH
CH3
C15H31
4I2
CH2
C
CH2
O H
O C
O
O
C
O
(CH2)7 CH CH (CH2)7 CH3
(CH2)7
CHCH
CH2
CHCH
CH2
CHCH
CH3
C15H31
I I I I I I
I I
dioksan
854 g glyceride - 4 . 254 g iodine
100 g - x
x = 119,9 g
Thank You