2. CChheemmiissttrryy ooff LLiippiiddss
Definition:
- Lipids are organic compounds formed mainly from
alcohol and fatty acids combined together by ester
linkage.
O
OH C R
R CH2
Fatty alcohol
HO
Fatty acid
+
H2O
O
R CH2 O C R
Esterase (lipase) ester (lipid)
3. - Lipids are insoluble in water, but soluble
in fat or organic solvents (ether,
chloroform, benzene, acetone).
- Lipids include fats, oils, waxes
and related compounds.
They are widely distributed in nature
both in plants and in animals.
4. Bi ol ogi cal Import ance
of Li pi ds :
1. They are more palatable and storable to unlimited amount
compared to carbohydrates.
2. They have a high-energy value (25% of body needs) and they
provide more energy per gram than carbohydrates and
proteins but carbohydrates are the preferable source of
energy.
3. Supply the essential fatty acids that cannot be synthesized by
the body.
4. Supply the body with fat-soluble vitamins (A, D, E and K).
5. They are important constituents of the nervous system.
6. Tissue fat is an essential constituent of cell membrane and
nervous system. It is mainly phospholipids in nature that are
not affected by starvation.
5. 7-Stored lipids “depot fat” is stored in all human cells acts as:
A store of energy.
A pad for the internal organs to protect them from outside
shocks.
A subcutaneous thermal insulator against loss of body heat.
8-Lipoproteins, which are complex of lipids and proteins, are
important cellular constituents that present both in the
cellular and subcellular membranes.
9-Cholesterol enters in membrane structure and is used for
synthesis of adrenal cortical hormones, vitamin D3 and bile
acids.
10- Lipids provide bases for dealing with diseases such as
obesity, atherosclerosis, lipid-storage diseases, essential
fatty acid deficiency, respiratory distress syndrome
6. CCllaassssiiffiiccaattiioonn ooff LLiippiiddss
1. Simpl e l i pi ds ( Fat s &
Waxes )
2. Compl ex ( compound or
conj ugat ed l i pi ds )
3. Deri ved Li pi ds
4. Li pi d- as soc i at i ng
subs t ances
8. FFaattttyy aallccoohhoollss ((ggllyycceerrooll &&
sspphhiinnggoossiinnee))
Glycerol:
a trihydric alcohol (i.e., containing
three OH groups) and has the popular
name glycerin.
It is synthesized in the body from
glucose.
It has the following properties:
9. 1. Colorless viscous oily liquid with
sweet taste.
2. On heating with sulfuric acid or
KHSO4 (dehydration) it gives
acrolein that has a bad odor. This
reaction is used for detection of free
glycerol or any compound
containing glycerol.
CH2 OH
CH
CH2 OH
HO
CHO
CH
CH2
2 H2O
Heating, KHSO4
Glycerol Acrolein
10. 3-It combines with three molecules of nitric
acid to form trinitroglycerin (TNT) that is
used as explosive and vasodilator.
4-On esterification with fatty acids it gives:
Monoglyceride or monoacyl-glycerol: one
fatty acid + glycerol.
Diglyceride or diacyl-glycerol: two fatty
acids + glycerol.
Triglyceride or triacyl-glycerol: three fatty
acids + glycerol.
5-It has a nutritive value by conversion into
glucose and enters in structure of
phospholipids.
11. UUsseess ooff GGllyycceerrooll::
1. pharmaceutical and cosmetic
preparations.
2. Reduces brain edema in cerebrovascular
disease.
3. Nitroglycerin is used as vasodilator
especially for the coronary arteries, thus it
is used in treatment of angina pectoris.
4. explosives manufacturing.
5. treatment of glaucoma (increased
intraocular pressure)due to its ability to
dehydrate the tissue from its water
content.
12. SSpphhiinnggoossiinnee::
- the alcohol(monohydric) present in
sphingolipids.
- synthesized in the body from serine
and palmitic acid.
It is not positive with acrolein test.
CH CH NH2
CH2OH
CH3 (CH2)12 CH CH
OH
Sphingosine
13. FFaattttyy AAcciiddss
DDeeffiinniittiioonn:
aliphatic mono-carboxylic acids that
are mostly obtained from the
hydrolysis of natural fats and oils.
the general formula R-(CH2)n-COOH
and mostly have straight chain (a few
exceptions have branched and heterocyclic chains).
"n" is mostly an even number of
carbon atoms (2-34)
15. 1-Saturated Fatty Acids
no double bonds with 2-24 or more
carbons.
solid at RT except if they are short
chained.
may be even or odd numbered.
molecular formula, CnH2n+1COOH.
20. 2-Unsaturated Fatty
Acids
- contain double bond
- TYPES:
A. monounsaturated
they contain one double bond .
(CnH2n-1 COOH)
B. polyunsaturated
they contain more the one double bond
(CnH2n-# COOH).
21. A-Monounsaturated fatty acids:
1-Palmitoleic acid :
It is found in all fats.
It is C16:1Δ9, i.e., has 16 carbons
and one double bond located at
carbon number 9 and involving
carbon 10.
CCHH33--(( CCHH22 ))55CCHH == CCHH--((CCHH22))77 ––CCOOOOHH
23. 3-Nervonic acid
(Unsaturated lignoceric acid).
It is found in cerebrosides.
It is C24:1D15, i.e., has 24 carbons
and one double bond located at
carbon number 15 and involving
carbon 16.
CCHH33 –– ((CCHH22))77 CCHH== CCHH –– ((CCHH22))1133-- CCOOOOHH
24. B-Polyunsaturated fatty acids :
(Essential fatty acids):
Definition:
They are essential fatty acids that
can not be synthesized in the
human body and must be taken in
adequate amounts in the diet.
They are required for normal growth
and metabolism
25. Source: vegetable oils such as corn oil,
linseed oil, peanut oil, olive oil, cottonseed
oil, soybean oil and many other plant oils,
cod liver oil and animal fats.
Deficiency: Their deficiency in the diet leads
to nutrition deficiency disease.
SSyymmppttoommss:: poor growth and health with
susceptibility to infections, dermatitis,
decreased capacity to reproduce, impaired
transport of lipids, fatty liver, and lowered
resistance to stress.
26. FFuunnccttiioonn ooff EEsssseennttiiaall FFaattttyy AAcciiddss::
1.They are useful in the treatment of atherosclerosis by
help transporting blood cholesterol and lowering it and
transporting triglycerides.
2.The hormones are synthesized from them.
3.They enter in structure of all cellular and subcellular
membranes and the transporting plasma
phospholipids.
4.They are essential for skin integrity, normal growth
and reproduction.
5.They have an important role in blood clotting
(intrinsic factor).
6.Important in preventing and treating fatty liver.
7.Important role in health of the retina and vision.
8.They can be oxidized for energy production.
27. POLYUnsat FA:
11--LLiinnoolleeiicc::
C18:2D9, 12.
It is the most important since other
essential fatty acids can be
synthesized from it in the body.
CCHH33--((CCHH22))44--CCHH == CCHH--CCHH22--CCHH==CCHH--((CCHH22))77--
CCOOOOHH
29. POLYUnsat FA:
33--AArraacchhiiddoonniicc aacciidd:
C20:4D5, 8, 11, 14.
It is an important component of
phospholipids in animal and in peanut
oil from which prostaglandins are
synthesized.
CCHH33--((CCHH22))44--CCHH==CCHH--CCHH22--CCHH==CCHH--CCHH22--
CCHH==CCHH--CCHH22--CCHH==CCHH--((CCHH22))33--CCOOOOHH
30. CCllaassssiiffiiccaattiioonn ooff LLiippiiddss
1. Simpl e l i pi ds ( Fat s &
Waxes )
2. Compound or conj ugat ed
l i pi ds
3. Deri ved Li pi ds
4. Li pi d- as soc i at i ng
subs t ances
33. They are esters of glycerol with various ffaattttyy aacciiddss..
SSiinnccee tthhee 33 hhyyddrrooxxyyll ggrroouuppss ooff ggllyycceerrooll aarree eesstteerriiffiieedd,,
tthhee nneeuuttrraall ffaattss aarree aallssoo ccaalllleedd ““TTrriiggllyycceerriiddeess””..
EEsstteerriiffiiccaattiioonn ooff ggllyycceerrooll wwiitthh oonnee mmoolleeccuullee
ooff ffaattttyy aacciidd ggiivveess mmoonnooggllyycceerriiddee,, aanndd tthhaatt
wwiitthh 22 mmoolleeccuulleess ggiivveess ddiiggllyycceerriiddee..
H2C O
O C H
H2C
C
C
O C
R1
R3
R2
O
O
O
+
3 H2O
CH2 OH
HO C H
CH2 OH
O
HO C R1
O
HO C R2
O
HO C R3
Fatty acids Glycerol Triglycerides
(Triacylglycerol)
35. CH2 O
O C H
CH2
C
C
O C
(CH2)14
O
O
O
Tripalmitin
(simple triacylglycerol)
CH3
CH3 (CH2)14
(CH2)14 CH3
CH2 O
O C H
CH2
C
C
O C
(CH2)16
O
O
O
1-Stearo-2,3-diolein
(mixed triacylglycerol)
CH3
CH3 (CH2)7 CH CH (CH2)7
(CH2)7 CH CH (CH2)7 CH3
CH2 O
O C H
CH2
C
C
O C
(CH2)14
O
O
O
1-palmito-2-oleo-3-stearin
(mixed triacylglycerol)
CH3
(CH2)16 CH3
CH3 (CH2)7 CH CH (CH2)7
37. PPhhyyssiiccaall pprrooppeerrttiieess ooff ffaatt aanndd
ooiillss::
1. Freshly prepared fats and oils are colorless,
odorless and tasteless.Any color, or taste is due
to association with other foreign substances, e.g.,
the yellow color of body fat or milk fat is due to
carotene pigments(cow milk).
2. Fats have specific gravity less than 1 (one) and,
therefore, they float on water.
3. Fats are insoluble in water, but soluble in organic
solvents as ether and benzene.
4. Melting points of fats are usually low, but higher
than the solidification point,
38. CChheemmiiccaall PPrrooppeerrttiieess ooff ffaattss aanndd
ooiillss:
11--HHyyddrroollyyssiiss::
hhyyddrroollyyzzeedd iinnttoo tthheeiirr ccoonnssttiittuueennttss ((ffaattttyy aacciiddss aanndd ggllyycceerrooll)) bbyy
hheeaatteedd sstteeaamm,, aacciidd,, aallkkaallii oorr eennzzyymmee ((ee..gg..,, lliippaassee ooff ppaannccrreeaass))..
-- DDuurriinngg tthheeiirr eennzzyymmaattiicc aanndd aacciidd hhyyddrroollyyssiiss ggllyycceerrooll aanndd ffrreeee
ffaattttyy aacciiddss aarree pprroodduucceedd..
CH2 O
O C H
CH2
C
C
O C
R1
R3
R2
O
O
O
Lipase or Acid O
3 H2O
H2C OH
HO C H
H2C OH
O
R1 C OH
+ R2 C OH
O
R3 C OH
Triacylglycerol Glycerol Free fatty acids
39. 2-Saponification.
>>Alkaline hhyyddrroollyyssiiss pprroodduucceess ggllyycceerrooll aanndd ssaallttss ooff
ffaattttyy aacciiddss ((ssooaappss))..
SSooaappss ccaauussee eemmuullssiiffiiccaattiioonn ooff ooiillyy mmaatteerriiaall tthhiiss hheellpp
eeaassyy wwaasshhiinngg ooff tthhee ffaattttyy mmaatteerriiaallss
CH2 O
O C H
CH2
C
C
O C
R1
R3
R2
O
O
O
H2C OH
HO C H
H2C OH
O
R1 C ONa
O
+ R2 C ONa
O
R3 C ONa
Triacylglycerol Glycerol Sodium salts of
fatty acids (soap)
3 NaOH
43. 55--OOxxiiddaattiioonn ((RRaanncciiddiittyy))
This toxic reaction of triglycerides leads to
unpleasant odour or taste of oils and fats developing
after oxidation by oxygen of air, bacteria, or
moisture.
Also this is the base of the drying oils after exposure
to atmospheric oxygen.
Example is linseed oil, which is used in paints and
varnishes manufacturing
= RANCID
46. CH2 O
O C H
CH2
C
C
O C
R1
R3
R2
O
O
O
Lipase O
3 H2O
H2C OH
HO C H
H2C OH
O
R1 C OH
+ R2 C OH
O
R3 C OH
Triacylglycerol Glycerol Free fatty acids
(volatile, bad odor)
48. Polyunsaturated fatty acid
Oxidant, O2
Peroxyradical
Hydroperoxide
Hydroxy fatty acid
Cyclic peroxide
Aldehydes
such as malondialdehyde
Other fragments
such as dicarboxylic acids
53. TTyyppee ooff WWaaxxeess:
- Waxes are widely distributed in nature
such as the secretion of certain insects as
bees-wax, protective coatings of the skins
and furs of animals and leaves and fruits
of plants. They are classified into true-waxes
and wax-like compounds as
follows:
AA--TTrruuee wwaaxxeess: include:
BBeeeess--wwaaxx is secreted by the honeybees
that use it to form the combs. It is a
mixture of waxes with the chief
constituent is mericyl palmitate.
61. AA--GGllyycceerroopphhoosspphhoolliippiiddss
11--PPhhoosspphhaattiiddiicc aacciiddss::TThheeyy aarree mmeettaabboolliicc
iinntteerrmmeeddiiaatteess iinn ssyynntthheessiiss ooff ttrriiggllyycceerriiddeess
aanndd ggllyycceerroopphhoosspphhoolliippiiddss iinn tthhee bbooddyy aanndd
mmaayy hhaavvee ffuunnccttiioonn aass aa sseeccoonndd mmeesssseennggeerr..
TThheeyy eexxiisstt iinn ttwwoo ffoorrmmss aaccccoorrddiinngg ttoo tthhee
ppoossiittiioonn ooff tthhee pphhoosspphhaattee
a
CH2 O
b
O C H
a
CH2
C
C
O
O P
R1
R2
O
O
OH
OH
a-Phosphatidic acid
Saturated
Polyunsaturated fatty acid
fatty acid
Phosphate
a
CH2 O
C H
CH2
C
O
R1
O
Saturated
fatty acid
Polyunsaturated
fatty acid
O
PhosphateHO P
O
OH
O
C R2
b
a
b-Phosphatidic acid
63. LLyyssoolleecciitthhiinn ccaauusseess hheemmoollyyssiiss ooff RRBBCCss.. TThhiiss
ppaarrttiiaallllyy eexxppllaaiinnss ttooxxiicc eeffffeecctt ooff ssnnaakkee
vveennoomm,,.. TThhee vveennoomm ccoonnttaaiinnss lleecciitthhiinnaassee,,
wwhhiicchh hhyyddrroollyyzzeess tthhee ppoollyyuunnssaattuurraatteedd
ffaattttyy ccoonnvveerrttiinngg lleecciitthhiinn iinnttoo llyyssoolleecciitthhiinn..
LLyyssoolleecciitthhiinnss aarree iinntteerrmmeeddiiaatteess iinn
mmeettaabboolliissmm ooff pphhoosspphhoolliippiiddss.
CH2 O
O C H
CH2
C
C
O
O P
R1
R2
O
O
O
OH
a-Lecithin
CH3
CH2 CH2 N
CH2 O
C H
CH2
+
CH3
C
O
CH3
R1
O
O
P
OH
b-Lecithin
O
C R2
CH3
+
N CH2 CH2 O
CH3
CH3
Choline
Choline
O
68. Properties: SSiimmiillaarr ttoo lleecciitthhiinnss.
CH2
O C H
CH2
C
O CH CH R1 fatty alcohol
O
O P
R2
O
O
OH
a,b-Unsaturated
CH2 CH2 N
a-Plasmalogen
CH3
CH3
+
CH3
69. 55--IInnoossiittiiddeess:
DDeeffiinniittiioonn::
- TThheeyy aarree pphhoosspphhaattiiddyyll iinnoossiittooll..
SSttrruuccttuurree: TThheeyy aarree ssiimmiillaarr ttoo lleecciitthhiinnss oorr
cceepphhaalliinnss bbuutt tthheeyy hhaavvee tthhee ccyycclliicc ssuuggaarr
aallccoohhooll,, iinnoossiittooll aass tthhee bbaassee.. TThheeyy aarree
ffoorrmmeedd ooff ggllyycceerrooll,, oonnee ssaattuurraatteedd ffaattttyy aacciidd,,
oonnee uunnssaattuurraatteedd ffaattttyy aacciidd,, pphhoosspphhoorriicc aacciidd
aanndd iinnoossiittooll
CH2
O C H
CH2
C
O
O C R1
O
O P
R2
O
OH OH
O
1
H H OH
H
a-Phosphatidylinositol
H
OH
2 3
OH
H
OH H
4
6 5
71. 66--CCaarrddiioolliippiinnss::
DDeeffiinniittiioonn: TThheeyy aarree ddiipphhoosspphhaattiiddyyll--
ggllyycceerrooll.. TThheeyy aarree ffoouunndd iinn tthhee iinnnneerr
mmeemmbbrraannee ooff mmiittoocchhoonnddrriiaa iinniittiiaallllyy iissoollaatteedd
ffrroomm hheeaarrtt mmuussccllee ((ccaarrddiioo)).. IItt iiss ffoorrmmeedd ooff 33
mmoolleeccuulleess ooff ggllyycceerrooll,, 44 ffaattttyy aacciiddss aanndd 22
pphhoosspphhaattee ggrroouuppss..
FFuunnccttiioonn:: UUsseedd iinn sseerroollooggiiccaall ddiiaaggnnoossiiss ooff
aauuttooiimmmmuunniittyy ddiisseeaasseess..
CH2
O C H
CH2
C
O
O C R1
O
O P
R2
O
Cardiolipin
O
OH
CH2
H C OH
CH2
H C O
CH2 CH2
C
P O
R3
O
O
OH
O
R4 C O
O
75. 11--CCeerreebbrroossiiddeess::
Occurrence: They occur in myelin sheath of nerves and
white matter of the brain tissues and cellular
membranes. They are important for nerve conductance.
Structure: They contain sugar, usually b-galactose and
may be glucose or lactose, sphingosine and fatty acid,
but no phosphoric acid.
Sphingosine
CH CH NH
CH2
CH3 (CH2)12 CH CH
OH
O
C R1
O
CH2OH
OH O
Galactose
H H
H OH
H H OH
Psychosin
Fatty acid
Ceramide
Cerebroside
82. PPhhyyssiiccaall pprrooppeettiieess::It has a hydroxyl group
on C3, a double bond between C5 and C6, 8
asymmetric carbon atoms and a side chain
of 8 carbon atoms.
It is found in all animal cells, corpus luteum
and adrenal cortex, human brain (17% of
the solids).
In the blood (the total cholesterol amounts
about 200 mg/dL of which 2/3 is esterified,
chiefly to unsaturated fatty acids while the
remainder occurs as the free cholesterol.
CH3
CH3
HO
CH3
CH3
CH3
Cholesterol
83. CChheemmiiccaall pprrooppeerrttiieess IInntteessttiinnaall bbaacctteerriiaa
rreedduuccee cchhoolleesstteerrooll iinnttoo ccoopprroosstteerrooll aanndd
ddiihhyyddrroocchhoolleesstteerrooll..
-- IItt iiss aallssoo ooxxiiddiizzeedd iinnttoo 77--
DDeehhyyddrroocchhoolleesstteerrooll aanndd ffuurrtthheerr uunnssaattuurraatteedd
cchhoolleesstteerrooll wwiitthh aa sseeccoonndd ddoouubbllee bboonndd
bbeettwweeeenn CC77 aanndd CC88.. WWhheenn tthhee sskkiinn iiss
iirrrraaddiiaatteedd wwiitthh uullttrraavviioolleett lliigghhtt 77--
ddeehhyyddrroocchhoolleesstteerrooll iiss ccoonnvveerrtteedd ttoo vviittaammiinn
DD33.. TThhiiss eexxppllaaiinnss tthhee vvaalluuee ooff ssuunn lliigghhtt iinn
pprreevveennttiinngg rriicckkeettss..
CH3
CH3
HO
CH3
CH3
CH3
H
Coprosterol,
in feces
CH3
CH3
HO
CH3
CH3
CH3
H
Dihydrocholesterol,
in blood and other tissues
88. CH3
CH3
HO
CH3
C
Sodium-tauro or
glyco-cholate
R1 or R2 R1 or R2
O O
CH3
CH3
HO
CH3
C
Sodium-tauro or
glyco-chenodeoxycholate
OH
OH OH
H 2N
CH2 COO -Na+ H 2N (CH2)2 SO3
-Na+ Sodium glycate Sodium taurate
R1 R2