Vitamins & Lipids

1. BIOCHEMISTRY
VITAMINS
and
LIPIDS

2. fat soluble
Vitamins
water soluble

3. Vitamin A (Wald’s visual cycle)
Retinol (vitamin A alcohol)
Retinal (vitamin A aldehyde)
Retinoic acid (vitamin Aacid)
β-carotene (provitaminA)
Carotenes are hydrolysed by
β-carotene 15-15‘-dioxygenase
Vit.A released from liver as free retinol,and
transported in the plasma by the plasma
retinol binding protein associated withpre-
albumin, target tissues cells contain cellular
retinol binding protein.
George Wald (NP1968)
rods and cones (types of retina cells)
Rods are involved in dim light vision, cones are
responsible for bright light and colour vision

4. Vitamin D
Ergocalciferol (plants)
and Cholecalciferol (in
animals) are sources for
vitamine D activity and
are reffered to as
provitamins. Vitamine D
is regarded as sun-shine
vitamine.
Concentration of 1,25-
DHCC is regulated by
plasma calcium and
phosphate. Low plasma
phosphate increase the activity of
25-hydroxycholecalciferol 1-
hydroxylase. Low plasma calcium
enhances the production of
parathyroid hormone, which in turn
activate 1-hydroxylase.

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6. Vitamin E Anti-sterility vitamin
(group of tocopherols:
α, β, γ, δ etc.
derivatives of 6-
hydroxy chromane
[tocol] ring)
α-tocopherol is most active.
Most of the function are released
to its antioxidant property –
preventing the non-enzymatic
oxidation by molecular oxygen
and free radicals. Protecta the
polyunsaturated fatty acids from
peroxidation reactions – it acts as
a scavenger and gets itself
oxidized (to quinon form).

7. Vitamin K1(philoquinone, menaquinone, menadone)
Vitamine K required for the
production of blood clotting
factors, essencial for coagulation(in
German-Koagulation – hence the name K for
this vitamine. It brings about the post-
translational (after protein biosynthesis inthe
cell) modification of certain blood clotting
factors. Also acts as a coenzyme for the
carboxylation of glutamic acid residues
present in the proteins and this reaction is catalysedby
a carboxylase (microsomal). It involves the conversion of
glutamate (Glu) to γ-carboxyglutamate (Gla) and requires
vitamin K, O2 and CO2. The formation of Gla is inhibited by
dicumarol, and anticoagulant found in the spoit sweet clover
(Warfarin is its synthetic analogue)

8. Vitamin B1 (Thiamine, Thiamine pyroposphate [TPP])
anti-beri-beri vitamin
The alcohol (OH) group of
thiamine is esterfied [catalysed by
thiaminepyrophosphate transferase] with
two phosphate forming
coenzyme thiamine
pyrophosphate (TPP)

9. Vitamin B1(Biochemical functions)
Biochemical functions
1.The enzyme pyruvate dehydrogenase catalyses (oxidative
decarboxylation) the irreversible conversion of pyruvate to acetyl CoA.
This reaction is dependent on TPP (thiamine pyrophosphate), besidesthe
other coenzymes.
2.α-ketoglutarate dehydrogenese (citric acid cycle)
3.Transketolase dependent on TPP (hexose monophosphate shunt)
4.The branch chain α-keto acid dehydrogenase (decarboxylase) request
TPP [in catalyses of axidative decarboxylation of branched chain amino
acids: vali, leucin, isoleucin] to the respective keto acids.
5.TPP plays an important role in the transmission of nerve impulse.

10. Vitamin B1 cocarboxylase: thiamine pyrophosphat
(TPP) – associated with carbohydrate metabolism
Pyruvate
dehydrogenase
α-ketoglutarate
dehydrogenase
Transketolase

11. Vitamin B2 (riboflavin) I
Riboflavin contain 6,7-dimethyl
isoalloxazine (a heterocyclic 3 ring
structure) attached to D-ribitol by a
nitrogen atom. Ribitol is an open chain
form of sugar ribose with the aldehyde
group (CHO) reduced to alcohol (CH2OH).

12. Vitamin B2 (riboflavin) –
flavin mononucleotide (FMD)
flavin adenin dinucleotide (FAD)
are two coenzymes forms
take part in redox reactions which are
responsible for energy production
Enzymes that use flavin coenzymes are called
flavoproteins
The functional unit of both the coenzymes is
isoalloxasine ring which serves as an acceptor of two
hydrogen atoms (with electrons). FMD and FAD
undergo identical reversible reactions formingFMNH2
of FADH2.

13. Vitamin (B3) niacine (nicotinamide) vitamin PP
Pellagra preventive (PP) factor of
Goldberg (identified by him).
The coenzymes of niacin (NAD+ and NADP+) can be
synthesized by essencial amino acid, tryptophan

14. Vitamin B3 (PP)
NAD (nicotinamide adenine dinucleotide)
Vit

15. Vitamin B5 (pantotenate)

16. Vitamin B6 (pyridoxine)i
Pyridine derivatives:
Pyridoxine
Pyridoxal
Pyridoxamine

17. Vitamin B6 (pyridoxine)ii
Piridoxal phosphat the coenzyme
which takes part in
transaminations, decarboxylation,
deamination, transsulfuration,
condensation

18. Vitamin C
(Ascorbinic acid)
Is a hexose derivative and
closely resembles
monosaccharides.

19. Vitamin C [biochemical function]i
1.Collagen formation (plays the role of coenzyme in
hydroxylation of proline and lysine while protocollagen is converted
to collagen [i.e. post-translational modification]; the hydroxylation
reaction is catalysed by lysyl hydroxylase (for lysine) and prolyl
hydroxylase (for proline). This reaction is dependent on vitamin C
molecular oxygen and α-ketoglutarate. Hydroxyproline and
hydroxylisine are essencial for the collagen cross-lincing and the
strength of the fiber. In this way, vitamin C is necessary form
maintenance of notmal connective tissue and wound healing process.
2.Bone formation (bone tissue possess an organic matrix,
collagen and the inorganic calcium, phosphate etc.)
3.Iron hemoglobine metabolism (enhances iron
absorption by keeping it in the ferros form – due to reduction property of
vitamin C. It helps in the formation of ferritin [storage form of iron]and
mobilization of iron from ferritin)

20. Vitamin C [biochemical function]ii
4.Tryptophan metabolism (vitamin C is essencial for the hydroxylation of tryptophan [enzyme-
hydroxylase] to hydroxytryptophan in the synthesis of serotonin)
5.Tyrosine metabolism (vitamin C is required for the oxidation of p-hydroxy phenylpyruvate[enzyme
hydroxylase] to homogetisic acid in tyrosine metabolism)
6.Folic acid metabolism (The active form of the vitamin folic acid is tetrahydrofolate [FH4] vitamin C is
needed for the formation of FH4 [enzyme-folic acid reductase]. Further, in association with FH4, ascorbic acid is involved in
the maturation of erythrocytes)
7.Peptide gormone synthesis (many peptide hormones contain carboxyl terminal amide which is derived
from terminal glycin. Hydroxylation of glycine is carried out by peptidylglycine hydrolase which requires vitamin C)
8.Synthesis of corticosteroid hormones (adrenal gland possesses high levels of ascorbinicacid,
particularly in periods of stress. It is believed that vitamin C is necessary for the hydroxylation reactions in the synthesis of
corticosteroid hormones)
9.Sparing action of other vitamins (strong antioxidant)
10.Immunological function (in synthesis of immunoglobulins)
11.Preventive action on cataract (reduces the risk of cataract)
12 .Preventive action on chronic diseases (antioxidant action)

21. Para aminobenzoic acid (PABA)
Regarded as a vitamin
in another vitamin
(in folic acid)

22. Lipids
The general rule of shorthand notation representing
fatty acid is to show the number of carbon atoms first,
followed by number of double bonds and finally the
(carbon) position of double bonds, starting from the
carboxyl end.
[saturated: palmic acid as 16:0;
oleic acid as 18:1; 9;
arachidonic acid as 20:4; 5, 8, 11, 14]

23. Lipids (conventional names)
There are other convention of representing the double
bond by writingΔ.
Δ9 indicates that the double bond is between 9 and 10
carbon of fatty acids.
ω9 – represents the double bond position (9 and 10)
from the ω end.

24. Lipids (table of main)

25. Some important fatty acids
Suturated fatty acids
Acetic acid [etanolic acid] 2:0 CH3COOH
Propionic acid [n-Propanolic acid] 3:0 CH3CH2COOH
Butyric acid [n-Butanolic acid] 4:0 CH3(CH2)2COOH
Valeric acid [n-Pentanoic acid] 5:0 CH3(CH2)3COOH
Capronic acid [n-Hexanoic acid] 6:0 CH3(CH2)4COOH
Caprylic acid [n-Octanoic acid] 8:0 CH3(CH2)6COOH
Capric acid [n-Decanoic acid] 10:0 CH3(CH2)8COOH
Lauric acid [n-Dodecanoic acid] 12:0 CH3(CH2)10COOH
Myristic acid [n-Tetradecanoic acid] 14:0 CH3(CH2)12COOH
Palmitic acid [n-Hexadecanoic acid] 16:0 CH3(CH2)14COOH
Stearic acid [n-Octadecanoic acid] 18:0 CH3(CH2)16COOH
Arachidonic acid [n-Eicosanoic acid] 20:0 CH3(CH2)18COOH
Behenic acid [n-Docosanoic acid] 22:0 CH3(CH2)20COOH
Lignoceric acid [n-Tetracosanoic acid] 24:0 CH3(CH2)22COOH

26. Unsaturated fatty acids
Palmitoleic acid [cis-9-Hexadecienoic acid]
16:1;9 CH3(CH2)5=CH(CH2)7COOH
Oleic acid [cis-9-Octadecienoic acid]
18:1;9 CH3(CH2)7=CH(CH2)7COOH
Linoleic acid [all cis, cis-9,12-Octadecadienoic acid]
18:1,9,12 CH3(CH2)4=CHCH2CH=CH(CH2)7COOH
Arachidonic acid [all cis, cis-5,8,11,14-Eicosatetranoic acid]
20: 5,8,11,14 CH3(CH2)4=CHCH2CH=CH(CH2)7COOH

27. Isomerism of fatty acids
Usually fatty acids exhibit
geometric isomerism
depending on the orientation of groups
around the double bond axis.
Most of the natural occurring unsaturated fatty acids exist as CIS
forms.
CIS isomers are less stable than TRANS isomers.

28. Essential fatty acids
Fatty acids that cannot be synthesized by the body and, therefore,
must be supplied in the diet – are known as
essential fatty acids [EFA].
Chemically, they are polyunsaturated fatty acids
Linoleic acid and linolenic acid
are essential since humans lack the enzymes that can introduce
double bonds beyond carbons 9 and 10.
The deficiency of EFAresults in phrynoderma and toad skin,
characterized by the presence of horny eruptions on the posterior
and lateral parts of limbs, on the back and buttocks, loss of hair and
poor wound healing.

29. Ionized form of fatty acids (Palmitate, Oleate)

30. Triacylglycerols (triacylglicerides, acylglycerols) are
the esters of glycerol with fatty acids.
Are abundant group of lipids that primarily function as
fuel reserves of animals.
Fats primarily occur in adipose tissue.

31. Triacylglycerols (triacylglicerides, acylglycerols) are
presented by
monoacylglycerols
diacylglycerols
triacylglycerols

32. Simple triacylglycerols Mixed triacylglycerols
Simple triacylglycerols contains the same type of fatty
acid residue at all three carbons.
Mixed triacylglycerols are more common. They
contain 2 or 3 different types of fatty acid residue.
In general, fatty acid attached to C1 is saturated, than
attached to C2 is unsaturated while that on C3 can be
either.
Triacylglycerols are named according to placement of
acyl radical on glycerol.

33. Properties of triacylglycerols
-hydrolysis (catalysed by lipases)
-saponification (hydrolysis by alkali [NaOH] produces
glycerol and soaps)
-rancidity (deterioration of fats and oils resulting in an
unpleasent taste) substances which can prevent the occurrence
of oxidative rancidity are known as antioxidants
[tocopherols (vitamin E), hydroquinone, gallic acid, α-naphtol;
propyl gallat, butylated hydroxyanisole (BHA), butylated
hydroxytoluene (BHT) – used in food preservation]
In the living cells, lipids undergo oxidation to produce
peroxides and free radicals which can damage the tissue

34. Tests to check purity of fats and oils
-iodine number grams [number] of iodine absorbed by
100 grams of fat – is useful to know the relative unsaturation of fats, and is directly
proportional to the content of unsaturated bonds in fatty acids
-saponification number – it is difined as the mg
[number] of KOH required to hydrolyse (saponify) ome
gram of fat or oil. It is a measure of the average molecular
size of the fatty acids present. The value is higher for fats containing short
chain fatty acids
-Reichert-Meissl (RM) number – it is defined as
number of ml 0.1 KOH required to completely neutralize
the soluble volatile fatty acids distilled from 5grams of
fat. RM – useful in testing the purity of butter since it contais a good concentration of valatile fatty acids
(i.e. butiric acid, caproic acid and caprylic acid) – this is in contrast to other fats/oils which have a neglible
amount of volatile fatty acids – adulteration of butter can be tested (if it is decrease).

35. Phospholipids (phosphoglycerides)
compound lipids containing phosphoric acid, in
addition to fatty acids, nitrogenous base and alcohol.
There are two classes of phospholipids:
-(A) glycerophospholipids (phosphoglycerides)
-(B) sphingophospholipides (sphingomyelins)
Principal structure of
phospholipids
(phosphoglyceride)

36. Phosphatidate (diacylglycerol 3-phosphate)

37. -(A) glycerophospholipids (phosphoglycerides)1
[contain glycerol and alcohol]
-consists of glycerol 3-phosphate esterified at its C1
and C2 with fatty acids. Usually, C1 contains a
saturated fatty acid, while C2 contains an unsaturated
fatty acid

38. Glycerophospholipids (phosphoglycerides)
They consist of glycerol 3-phosphate esteriffied its C1 and C2 with fatty
acids.
Usually C1 contains a saturated fattyacid
while C2 contains an unsaturated fatty acid.
1.Phosphatidic acid
2.Lecitins (phosphatidylcholin)[dipalmitol lecitin;
lysolecitin]
3.Cephalins (phosphatidylethanolamine)
4.Phosphatidylinositol
5. Phosphatidylserin
e 6.Plasmalogens
7.Cardiolipins

39. 1.Phosphatidic acid glycerophospholipids (phosphoglycerides)1
-phosphatidic acid – simplest phospholipid, does not occur in
good concentration in the tissues – basically it is an
intermediate in the synthesis of triacylglycerols and
phospholipids
Other glycerophospholipids containing different nitrogeneous bases or other groups

40. 2.Lecitins (phosphatidylcholin)[dipalmitol lecitin;
lysolecitin] glycerophospholipids (phosphoglycerides)2
-lecithins (phosphatidiylecholine) – [λεκιθος – agg yolk]
– storage form of body’s choline [dipalmitoyl lecithin – in
lungs; lysolecithin – is formed by removal of fatty acid either
at C1 or C2 of lecithin]

41. a phosphatidylcholine (lecine)
[1-palmitoyl-2-oleoil-phosphatidyl choline] and a space-filling model

42. 3.Cephalins (phosphatidylethanolamine)
glycerophospholipids (phosphoglycerides)3
-cephalins (phosphatidylethanolamine) – ethanolamine is
the nitrogenous base present; lecitine and cephaline differ with regardto
the base

43. 4.Phosphatidylinositol glycerophospholipids
(phosphoglycerides)4
-phosphatidylinosotol – important component of cell membranes
– stereoisomer myo-inositol is attached to phosphatidic acid.

44. 5. Phosphatidylserine glycerophospholipids (phosphoglycerides)5
-phosphatidylserine – amino acid serin is present in it

45. 6.Plasmalogens glycerophospholipids (phosphoglycerides)6
-plasmalogens – fatty acid is attached by an ether linkage at C1 of
glycerol in the glycerophospholipids.
(choline, inositol, serin may substitute ethanolamine in plasmalogens)

46. 7.Cardiolipins glycerophospholipids (phosphoglycerides)7
-cardiolipin – first isolated from heart muscle – consists of two
molecules of phosphatidic acid held by an additional glycero through
phoshate group

47. Components of phosphatidyls
(serine, ethanolamine, choline, glycerol, inositol)

48. Phoshatidyls (serine, ethanolamine, choline,
inositol,cardiolipin [diphosphatidil glycerol])

49. -(B) sphingophospholipides (sphingomyelins)1
[do not contain glycerol, but contain sphingosine and amino alcohol which are
attached by an amide linkage to a fatty acid]
-sphingosine
-cersamide

50. -sphingophospholipides (sphingomyelins)1 (space-
filling model of molecule)

51. Sphingophospholipides (sphingomyelins)
contains amino alcohol
-ceramide – containing 30-carbon fatty acid – is a
component of skin
ceramide (acts as a second messenger – signaling
molecile – which can regulate programmed cell death
[apoptosis])

52. Function of phospholipids
-they are forming the structural componentsbof mambranes and regulatemembrane
permeability;
-in the mitochondria (lecithins, cephalins and cardiolipins) maintain the conformation of
electron transport chain components;
-participate in the absorbtion of fat from intestine;
-are essential for the synthesis of different lipoproteins (participate in the transportof
lipids);
-are regarded as lipotropic factors in liver preventing accumulation of fat init
(preventing fatty liver);
-arachidonic acid (as unsaturated fatty acid liberated from phospholipids) serves as a
precursor for the synthesis of eicosanoids (prostaglandins, prostaciclins,thromboxans
etc.)
-participate in the reverse cholesterol transport and thus help in the removalof
cholesterol from the body;
-phospholipids act as surfactants (agents lowering surface tension) [inrespiratory
distress syndrome];
-cephalins are important lipids participate in blood clotting;
-phosphatidylinositol is the source of secondary messengers (inositol triphosphate and
diacylglycerol are involved in the action of some hormones

53. Glycolipids (contain a ceramide – sphingosine
attached to fatty acid)
Glycolipids – (glycosphignolipids) – important constituents of cell
membraine and nervous tissue (particulary in the brain).
Cerebrosides are the simpest form of glycolipids. They contain ceramide
(sphignosine attached to a fatty acid) and one or more sugars.
Gangliosides – predominantly found in ganglions – are the most complex
form of glycosphignolipids. They are the derivatives of cerebrosides and
contain one or more molecules of N-acetylneuramatic acid (NANA), the
most important sialic acid.
The most important gangliosides present in the brain are GM1, GM2,
GD, and GT (G represents ganglioside while M, D and T indicatemono-
di- or tri- sialic acid residues) and number denotes the carbohydrate
sequence attached to the ceramide

54. Lipoproteins (complexes of lipids with proteins)
Lipoproteins – are molecular complexes of lipids with
proteins.
They are the transport vehicles for lipids in the circulation.
There are five types of lipoproteins, namely:
-chylomicrons
-very low density lipoproteins (VLDL)
-low density lipoproteins (LDL)
-high density lipoproteins (HDL)
-free fatty acid-albumin complexes

55. Steroids
Steroids are the compounds containing a cyclic steroid
nucleus (or ring) namly
cyclopentanperhydrophenantren [CPPP]
It consists of a phenanthrene nucleus (rings A, B and
C) to which a cyclopentane ring (D) is attached

56. Cholesterol (χολε-bile) [C27H46O]
Exclusively found in animals, is the most abundant animal sterol.
Was first isolated from bile.
Cholesterol literally means ‘solid alcohol from bile’
It has one hydroxyl group at C3 and
double bond between C5 and C6.
An 8 carbon aliphatic side chain is attachanded to C17,
it also contains a total 5 methyl groups (C18, C19, C21, C26, C27)

57. Cholesterol (main properties and reactions)
Cholesterol is a yellowish crystalline solid, insoluble in water but
soluble in organic solvents (chloroform, bebzene, ether etc.).
Salkowski’s test
Liebermann-Burchard reaction
Zak’s test
are used for qualitative identification and quantitative estimation
Due to poor conduction of heat and electricity (it has a high
dielectric constant) cholesterol is present in abundance in nervous
tissues – it appears that it plays an insulating cover for transmission
of electrical impulses in the nervous tissue.
It is precursor in synthesis of bile acids, hormones (sex and
cortical) and vitamin D.

58. Ergosterol
Occur in plants, also found as a structural constituent of membranes in
yeast and fungi – is an important precursor for vitamin D. when rxposed
to light, the B ring of ergosterol opens and it is converted to
ergocalciferol, a compound containing vitamin D acivity.

59. Amphipatic lipids in the formation of
micelle and lipid bilayer
Per definition, - lipids are insoluble in water
(hydrophobic). This primary due to the prebolinant
presence of hydrocarbon groups. However, some of the
lipids possess polar of hydrophilic groups which tend to be
soluble in water. Molecules which contain both
hydrophobic and hydrophilic groups are known as
amphipatic (greek αμφι – both; παϑος – passion)

60. β-oxidation of fatty acids 1 (whole)

61. β-oxidation of fatty acids (I phase) activation

62. β-oxidation of fatty acids (II phase)

63. fatty acids acyls transport (through membrane) into
mitochondria (second phase) Transport

64. β-oxidation of fatty acids (III phase)
Beta oxidation
oxidation
hydration
oxidation
cleavage

65. Thank You for attention…