carbohydrates with their brief introduction and their classification. then structural features of carbohydrates

2. CARBOHYDRATES
• Aldehyde or Ketone derivatives of polyhydroxy
alcohols.
General formula
(CH2O)n

3. BIO MEDICAL IMPORTANCE
• Most abundant bio molecules.
• Main source of energy (4 kcal/gm) .
• Absolutely required for RBCs’ & brain cells.
• Storage form of energy i.e. starch & glycogen.
• Required for oxidation of fats.
• Excess CHO are converted into fats.
• Glyco protein & Glyco lipids are components of cell
membrane.
• Structural basis of many organisms.
• Used as drugs i.e. antibiotics & cardiac Glycosides.

4. CLASSIFICATION
• Monosaccharides
• Disaccharides
• Oligosaccharides
• Polysaccharides
• Derived carbohydrates

5. MONOSACCHARIDES
• Simplest sugars, cant be hydrolyzed into simpler
molecules.
• Further classified as,
Aldoses
Ketoses

6. NAME GENERAL
FORMULA
ALDOSES KETOSES
TRIOSES C3H6O3 GLYCER-
- ALDEHYDE
DIHYDROXY-
-ACETONE
TETROSES C4H8O4 ERYTHROSE ERYTHROLUSE
PENTOSES C5H10O5 RIBOSE RIBULOSE
HEXOSES C6H12O6 GLUCOSE FRUCTOSE
HEPTOSES C7H14O7 SEDOHEPTOLUSE
NONOSES C9H18O9 NEURAMINIC-
-ACID

7. DISACCHARIDES
• Condensation products of 2 monosaccharide units.
MALTOSE (D Glucose + D Glucose)
SUCROSE (D Glucose + D Fructose)
LACTOSE (D Glucose + D Galactose)

8. OLIGO SACCHARIDES
• Condensation products of 3-10 mono saccharide units,most
of them are not digested by human enzymes.
α DEXTRINS
MALTO TRIOSE

9. POLY SACCHARIDES
• Condensation products of > 10 mono saccharide
units.
HOMO POLY SACCHARIDES
HETRO POLY SACCHARIDES

10. HOMO POLYSACCHARIDES
• Have only one type of mono saccharide units.
• STARCH GLYCOGEN
• CELLULOSE INULIN
• DEXTRIN DEXTRAN
• CHITIN

11. HETRO POLYSACCHARIDES
MUCO POLY SACCHARIDES
• Also known as Glycosaminoglycan.
• Hyaluronic Acid,Chondriotin sulfate, Heparin sulfate,
Keratin sulfate, Dermatin sulfate, Blood group
substances.
GLYCO CONGUGATES
• Proteo glycans
• Glyco lipids
• Glyco proteins

12. DERIVED CARBOHYDRATES.
• Reduction products i.e. Polyols (glycerol)
• Oxidation products i.e. sugar acids
• Deoxy sugars i.e. DNA

13. MONOSACCHARIDES
TRIOSES
• Glyceraldehyde & Dihydroxy acetone.
1 Intermediates of glycolysis.
2 Precursor of Glycerol
TETROSES
• Erythrose-4-PO4
1 Intermediate of HMP shunt.

17. DEOXY SUGARS
• L- Fucose
• Deoxy Glucose
• D- Ribose
• L- Arabinose
• D- xylose

20. HEXOSES
• Glucose
• Fructose
• Galactose
• Mannose

21. MONOSACCHARIDES

22. PHYSICAL PROPERTIES
• Colorless, crystalline solids , sweet taste, water
soluble compounds.
• Aldoses
• Ketoses
• Poly Hydroxy alcohols i.e. having (OH-) groups
• Depending upon the no. of (OH-) groups, they
contain one or more centre of Asymmetry, which
affects their optical & biological activity.

23. • Dihydroxy acetone (ketotriose) is an exception,
(does not have any asymmetric carbon).
• Glyceraldehyde (aldotriose) is called as the
“REFERENCE SUGAR”.
Carbonyl carbon
Asymmetric carbon

24. STRUCTURAL ASPECTS
• ISOMERISM IN MONOSACCHARIDES
1. Stereo isomerism
2. Enantiomers
3. D & L isomers
4. Optical isomers
5. Aldose-Ketose isomers
6. Anomers
7. Epimers
8. Pyranose & Furanose isomers

25. STEROISOMERISM
• 2 or more Monosaccharides having same formula, but
differing from each other in structural configuration i.e.
spatial arrangement of H or OH atoms in their structure.

26. ASYMMETRICAL(CHIRAL) CARBON
• 4 different groups attached to the same carbon .
• Parent compound (reference molecule) is
• Glyceraldehyde (1 asymmetric C).

28. • In general a molecule with n chiral center can have 2n stereo
isomers.
• Glyceraldehyde 21
• Glucose 2 4

29. ENANTIOMERS
These are mirror images of
each other.
They form D & L isomers.
All mono saccharides can
be considered to be
derived from
Glyceraldehyde.

31. • The configuration of H & OH groups at the second Carbon
atom of Glyceraldehyde forms D & L sugars.
• Penultimate carbon atom is the reference carbon for
naming D & L mirror images.

32. • Non super imposable complete mirror images, differ
in configuration at every chiral center.
• In D form OH group is on the RIGHT , while in L
form OH group is on the LEFT of the chiral carbon.
• D & L isomers differ from each other by orientation
around PENULTIMATE CARBON
(C -5 in case of Glucose molecule)
,farthest from the carbonyl(C= O)carbon.
• Human body can metabolize D-sugars only.
• Naturally occuring sugars are D-sugars except
L-Arabinose .

34. OPTICAL ISOMERISM
• Presence of asymmetric C atom confers optical
activity to the carbohydrates.
• When a beam of plane polarized light is passed
through a carbohydrate solution
• It will rotate the light either
• to right DEXTRO ROTATORY(+)
• to left LEVO ROTATORY (-)

35. OPTICAL ISOMERISM
• The direction of rotation of plane polarized light is
independent of the stereo-chemistry of sugar.
• Sugar may be designated as,
D(-) ,D(+) or L(-) ,L(+)
• Naturally occuring form of Fructose is D but it is levo
rotatory. i.e. ( D-)
• Glucose is D sugar, but dextro rotatory i.e. (D+)

36. • Plane polarized light does not rotate to right or left, if
• Compound does not possess plane of asymmetry.
• Equal amounts of dextro or levo isomers are present
RECEMIC MIXTURE.
• Meso compounds having asymmetric carbon but due
to internal compensation i.e. Meso tartaric acid.

37. EPIMERS
• Sugars that differ only in the configuration
around one Carbon atom (other than
reference carbon).

39. ALDOSE-KETOSE ISOMERS

40. CYCLIC STUCTURE OF MONO
SACCHARIDES

41. • Cyclic structures are formed by the reaction between
an ALDEHYDE/KETONE group and a HYDROXYL group
in a monosaccharide with 5 or more carbon atoms.
• Cyclic structure is thermodynamically favored and accounts for many properties of mono -
saccharides

42. • The open chain form (FISCHER PROJECTION) is found in <
0.1% of the molecules in an aqueous solution.
• An intra molecular reaction in which one of the OH group
of the sugar is added to the Aldehyde/ Ketone group of
the same molecule ---- forms a cyclic structure.
• The cyclic (ring) structure is called ----------- HAWORTH
PROJECTION.
• The carbonyl carbon(C-1 of Aldose /C-2 OF KETOSE) in ring
structure is called ANOMERIC CARBON

43. HEMI ACETAL LINKAGE

44. HEMIKETAL LINKAGE

49. HEMI KETAL LINKAGE
• Condensation between Ketone group and a OH group forms
the hemi Ketal linkage.
• Condensation between the Aldehyde/Keto group is in 1:1.
• As a result of these linkages ANOMERIC CARBON gives an
additional asymmetric carbon.
• Depending upon the configuration, OH group are found
above or below the ring.
• OH group on the right in Fischer projection appear under
the ring in Haworth projection ,while those on the left are
above the ring.

50. • OH group at C-5 / C-6 reacts with the Keto group at C-
2, forming a FURANOSE/PYRANOSE cyclic structure
having a hemi Ketal linkage.
• D-Fructose readily forms the Furanose ring.
• Common anomer of Fructose is the β - D Fructose.

52. • In Aldohexoses the OH group at C-5 reacts with the c=o
group and forms a six member
• ring---PYRAN RING .
• Sugars having this ring are called PYRANOSES.
• If the OH group at C-4 reacts, a five member ring---
FURAN RING is formed &
• Sugars are called FURANOSES.
• OH group to the right is below the plane----α
• Oh group to the left is above the plane of symmetry---β

55. ANOMERS
• Anomeric carbon by giving an additional chiral carbon
makes the total isomers 25. (32)
• Anomeric carbon gives 2 stereo isomers i.e.
α & β ANOMERS .
• α & β forms are not Enantiomers.
• They differ only in respect to configuration around
Anomeric carbon.
• They are present only in cyclic form, & do not show
the Aldehyde group normally present in Glucose.
• Ring structure is also called AMYLENE OXIDE .
•

56. MUTA ROTATION
• In Glucose solution ,2/3 of sugar exist as β form,&
1/3 as α form.
• Inter conversion of α & β forms is called
MUTA ROTATION .
• In the solution there is opening of Hemiacetal ring
to form traces of Aldehyde sugar & then Re
condensation to the cyclic form.

59. • When plane polarized light is passed through a Molar
solution of D- Glucose, Its specific rotation keeps on
changing
• α- D Glucose in the solution shows --+112˳ while β-
Glucose shows ---- +19˳. After a
certain period of time two forms reach at an end point----
+19˳.
Mutarotation leads to an equilibrium between α & β forms
in which 62% of the molecules are present in the β form ,
while 38% in the α form.
a

60. CLINICAL SIGNIFICANCE
• α
& β Anomers can be obtained in pure forms.
•
• It is possible to determine the sugar content of
different beverages.

61. PYRANOSE/FURANOSE ISOMERS

63. BOAT & CHAIR ISOMERS

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