1 Classification of Classification of Glycosides Glycosides . On the basis of sugar moiety such as glucoside , rhamnoside, etc. n the basis of therapeutic activity such as Cardiac glycosides, e.g. Digitalis, Strophenthuss, etc. Laxative glycosides, e.g. Aloe, Senna, Cascara sagrada, etc. CH 2 OH O C 6 H 11 O 5 O OH O H OH OH H O H CH 2 OH H H OH Salicin (saligenin + glucose) Arbutin (hydroquinone + glucose)
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Classification of GlycosidesClassification of Glycosides
A.A. On the basis of sugar moiety such as glucoside , rhamnoside, etc.
A.B. On the basis of therapeutic activity such as - Cardiac glycosides, e.g. Digitalis, Strophenthuss, etc.- Laxative glycosides, e.g. Aloe, Senna, Cascara sagrada, etc.
CH2OH
O C6H11O5
O
OH
O
H
OH
OH
HO
H
CH2OH
HH
OH
Salicin (saligenin + glucose)
Arbutin (hydroquinone + glucose)
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C. On the basis of linkage of sugar molecule with the aglycon a) O- Glycosides: here the sugar is combined with the
alcoholic or phenolic hydroxyl group of the aglycone.
RO
R = Glucose in daucosterol
ORO
OH O
OCH3
OHR = Rhamnose - glucose
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b) N- Glycosides: In these glycosides the amino group (-NH2 / -NH-) is condensed with the sugar, e.g. nucleosides, coenzyme, etc.
N
N
N
N
NH2
H
H H
OCH2OH
H
OH OH
N
NN
N
NH2
H
O OH
H HCH2
P
O
O-O
O
PH O-HO
O
PH
CH2
O-HO
CH3C CH3
CHO CH
H
HN
OH
CH
OH
HN
SH
H
O
Adenosine (Adenine + ribose)
Coenzyme A
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d) C- Glycosides: Condensation of a sugar directly to a carbon atom of the aglycone gives c-glycosides, e.g. aloin, chrysaloin, etc.
OH O OH
H C6H11O5
CH2R
O
CH3
C6H11O5
HO CH3
O
OR = OH, Barbaloin H, Chrysaloin
Aloesin
c) S- Glycosides: These glycosides contain a sugar moiety attached to the sulfur of the aglycone, e.g. isothiocyanate glycosides.
C3H5 C
N
S C6H11O5
O SO3K
Sinigrin
HO CH2 C
S
N O
C6H11O5
SO2-O-K
Sinalbin
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D) On the basis of the chemical nature of aglycone, the glycosides can be classified into following groups:
An acetal is a molecule with two single bonded oxygen attached to the same carbon atom.
Hemiacetals and hemiketals are compounds derived from aldehyde and ketones respectively. These compounds are formed by formal addition of an alcohol to the carbonyl group.