monosaccharides and disaccharides their structure , role and importance in the body and other uses

1. Monosaccharide and
disaccharides

2. D-GLUCOSE (grape sugar)
• SOURCES
• Fruit juices, Cane / Beetroot, maltose, Lactose,
Hydrolysis of Starch.
• Main metabolic fuel------ (Blood sugar)
• Fasting Blood Glucose level (70-110 mg / dl )
• Principle Hexose utilized by the body to obtain
energy.
• Normally all of the Glucose is reabsorbed by the
renal tubules.
• TMG ---- 375 mg /min.
• Renal threshold ----- 180 mg / dl

3. Glucose is not a true aldehyde

5. • On oxidation Glucose gives 3 types of sugar acids.
• Glucoronic acid (oxidation product in humans) is
important for xenobiotic metabolism & GAGs’
synthesis.
• Sorbitol (reduction product) causes cataract.

6. D-FRUCTOSE (Fruit sugar)
• SOURCES
• Fruit juices, Honey, Cane / Beetroot, Sucrose,
Inulin & enzymatic isomerization of Glucose
syrup commercially.
• Readily metabolized in the body either directly
or via Glucose.
• Seminal fluid has Fructose as nutrient for
spermatozoa.
• Can occur in both Furanose & Pyranose forms.

8. • Keto Hexose, shows mutarotation.
• D- sugar. when free (Pyranose form ) ,it
occurs in Levorotatory form.
• Sucrose has Fructose in Furanose form,
which is Dextrorotatory.
• Sweetest of all sugars.
• Hereditary Fructose Intolerance (Aldolase
–B enzyme deficiency ) causes fasting
hypoglycemia & fructose accumulation.

9. D-GALACTOSE (MILK SUGAR )
• SOURCES
• Milk ,Hydrolysis of starch ,seeds of Legumes.
• Readily metabolized to Glucose in the liver .
• Synthesized in lactating mammary glands for milk
production.
• Required for synthesis of muco proteins .
• Constituent of Glycolipids &Glycoproteins.
• Epimer of Glucose at C-4.
• Dextrorotatory , shows muta rotation.
• CLASSICAL GALACTOSEMIA (GALT enzyme
deficiency)

10. D-MANNOSE
• SOURCES
• Hydrolysis of plant Gum Mannan ( not present
in free form) .
• Present in Glycoproteins& polysaccharides.
• Gets converted into Glucose in human body.
• C-2 epimer of Glucose.

11. DISACCHARIDES

12. DISACCHARIDES
• Sugars composed of two mono saccharide
units joined by α -Glycosidic bond.
• MALTOSE
• SUCROSE
• LACTOSE
• LACTULOSE
• TREHALOSE

13. MALTOSE

14. • COMPOSITION
• O α- D- Glucopyranosyl (1-4) α-D-
Glucopyranosyl
• MALT sugar
• SOURCES
• Malt, germinating cereals, enzymatic
hydrolysis of starch by salivary & pancreatic
Amylases.
• Maltase enzyme hdrolyzes Maltose into
Glucose.
• strong reducing agent.
• Shows muta rotation.
• Forms sun flower shaped Osazone crystals.

16. ISOMALTOSE
• Enzymatic hydrolysis of branch points of the
AMYLOPECTIN unit of Starch.
• Shows α-(1-6) linkage.

17. LACTOSE
• SOURCES
• Milk ,pharmaceutical preparations.
• COMPOSITION
• O-β -D- Galactopyranosyl (1-4)-β- D- Glucopyranosyl
• Synthesized in mammary glands ,can appear in the
urine of lactating mothers.---LACTOSURIA.
• COW S’ milk contains 45% Lactose.
• Human milk contains 74% Lactose.
• Reducing sugar ,shows muta rotation.

19. LACTOSE INTOLERANCE
• Lactase deficiency
• Diarrhea ,flatulence , dehydration .
• Treatment
• Stop breast feeding/ milk intake.
• Yoghurt ,cheese & green vegetables for Ca++
intake.
• Lactase pills.

22. LACTULOSE
• O-α –D Galactopyranosyl (1-4 )-β-D Fructopyranosyl
• SOURCES
• Heated Milk , synthetically produced .
• Can not be hydrolyzed by intestinal enzymes .
• Fermentation by intestinal bacteria .
• USES
• Mild Diuretic /osmotic laxative .

23. SUCROSE (TABLE SUGAR )
• O α -D –Glucopyranosyl (1-2) β- D- fructofuranose
sources
• Cane ,beetroot,sorgham,fruits & vegetables.
• Non reducing sugar ,
• Does not form Osazone crystals.
• Does not exhibit muta rotation .
• Dextro rotatory sugar ( + 66.5 )
• On hydrolysis it becomes strongly Levorotatory
(- 28.2)

25. • INVERT SUGAR
• Hydrolytic products of Sucrose are called invert sugars.
• Sucrose hydrolysis by Sucrase/ dilute acids liberates
one molecule each of α D- Glucopyranose & β –D
Fructofuranose.
• β D- Fructofuranose form is unstable & immediately
gets converted to β –D Fructopyranose form, which is
strongly Levorotatory ( -92 )
• Overall effect is INVERSION of dextro rotatory Sucrose
(+66.5) to Levorotatory.( - 22.8)
• Invert sugars are 33% more sweet than Sucrose i.e.
Honey

26. TREHALOSE
• O α-D Glucopyranosyl (1-1) α-D Glucopyranosyl
• SOURCES
• Fungi, yeast

27. OLIGO SACCHARIDES
• 3-10 carbohydrate units.
• Components of integral membrane proteins,
present on their extra cellular domain.
• Mostly contain Mannose /Sialic acid residues.
• Help in degradation of these integral proteins.
• EXAMPLES
• Glycoproteins
• Antibodies
• Coagulation factors