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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

II) Hexoses

Practically, there are only two sugars (D-glucose and D-Fructose), which

occur in nature in the free state. D-Glucose and D-fructose as well as D-mannose,

D-galactose, L-galactose and some other sugars are occurring in combined form

in nature.

• Identification:

Test Result Positive with

Fehling’s red ppt is due to Cu 2O ppt monosaccharide and red. disaccharide

Barfoed’s red ppt is due to Cu 2O ppt monosaccharide only

Osazone Definite crystal shapes monosaccharide and red. disaccharide

e.g: Fructosazone

Test for Ketoses

Seliwanoff’s Red color fructose & sucrose

Cobalt Violet color fructose & sucrose

nitrate

1) D- (+)-Glucose:

• Other names (Synonyms): dextrose, grape sugar, corn sugar, blood sugar.

• The most common sugar in nature, it occurs either free or in combined form.

• D-glucose is found in ripe grapes, honey, most sweet fruits, plant starch,

cellulose, disaccharides (lactose, maltose, and sucrose). It is also a normal

constituent of blood and occurs in the urine of diabetics.

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