Mona Farouktec.horus.edu.eg/wp-content/uploads/2018/03/glycoside-3... · 2018-03-06 · 1,...
Transcript of Mona Farouktec.horus.edu.eg/wp-content/uploads/2018/03/glycoside-3... · 2018-03-06 · 1,...
Vice chairman of quality assurance and accreditation unit
Supervisor for EPSF-Mansoura
Lecturer - Pharmacogosy department,
Faculty of Pharmacy, Mansoura University
3
Mona Farouk 2
Classification according to chemical nature
Holosides
the aglycone is sugar
Heterosides
the aglycone is not a sugar
Alcoholic
(e.g: Salicin)
Aldehydic(e.g: Gluco-vanillin)
Phenolic
Simple phenolic
(e.g: Arbutin) Anthracene or
anthraquinone
(e.g: Gluco-aloe-emodin)
Flavonoidal
(e.g: Rutin)
Coumarin
(e.g: umbelliferon
SteroidalSaponin
Cyanogenetic
(e.g: Amygdalin
Thio-glycosides
(e.g: Sinigrin).
The phenolic aglycones are classified into:
1. Simple phenolic glycosides.
2. Coumarin glycosides
3. Lignans and neolignans xxx
4. Anthraquinones glycosides
5. Flavones and related flavonoid glycosides
1-Salicin 2-Coniferin 3. Arbutin
Source: bearberry (Uva ursi) leaves.
Hydrolysis: acids or emulsin it yields hydroquinone
and glucose.
Chemical test: + FeCl3 gives violet col.
Uses:
1. diuretic
2. renal antiseptic is due to the
hydroquinone given by
hydrolysis.
3. Arbutin is used for skin whitening. It is proved to be a good
inhibitor for melanin synthesis and may be used in
hyperpigmentation disorders.
These constitute a group of glycosides, of which the aglycone is
either coumarin or
a coumarin derivative (Hydroxy and methoxy coumarins).
Coumarin umbelliferon Daphinin
Detection: The aqueous solution of all coumarins and its derivatives
have blue or violet fluorescence in UV 366 nm.
Intensifies by aq. ammonia solution.
Umbelliferon is a natural coumarin
Source: in some resins of Galbanum, and Asafetida
Coumarin importance
A natural fragrant substance has a sweet odor,
and has been used in perfumes industry.
Coumarin is used in the pharmaceutical industry as a precursor
in the synthesis of a number of synthetic anticoagulant
pharmaceuticals similar to dicoumarol, e.g. warfarin, they act
in the liver by interfering with the action of vitamin K.
Coumarins e.g:diosmin, are an edema modifier. They stimulate
macrophages to degrade extracellular albumin, allowing faster
resorption of edematous fluids.
Its strong absorption of ultraviolet light at several wavelengths
led to its use as a sunscreen agent.
Anthraquinones are widely distributed in plants.
Mainly used as purgative drugs
e.g: Senna, Rhubarb, Cascara, Frangula and Aloes
These anthraquinone derivatives, occur
in both the free state and as glycosides
Properties of Anthrquinone derivatives:
They are usually red or yellow colored.
When free, they are of low solubility in water.
These for mentioned subgroups may occur in the form :
1) Free aglycones: e.g: anthraquinones.
2) O-glycosides. 3) C- glycosides
They are usually more soluble in hot water and dilute
alcohols, glycosides show greater solubility in water.
Anthraquinone derivatives give reddish coloration with
alkali, a fact on which Borntrager’s Reaction is based
Tests for identity:
1)Bornträger’s test: pink or red in aqueous layer.
2)Modified Bornträger’s test: pink or red in aqueous layer.
3)Micro-sublimation: The sublimate form needle crystals that
acquires red color with a drop of alkali
Quantitative determination of anthracene glycosides
Colorimetric method:
After hydrolysis with acid, the aglycone is allowed to react with
KOH to give red or violet color.
The intensity of this color is directly proportional to the
concentration of anthraquione, and can be measured
colorimetrically.
Anthranol contents can, similarly, be determined but after
oxidation with FeCl3 or H2O2
1, 8-anthraquinone derivatives exert a more or less violent laxative or
purgative activity.
Anthraquinone glycosides may be considered prodrugs: the sugar
moiety is essential for the pharmacological action, as it serves to
transport the aglycone to the site of action in the large intestine.
They exert their action by:
(A) Increasing the peristaltic movement of the large
intestine causing soft evacuation.
(B) Stimulate the secretion of water and electrolytes into the large
intestine.Side effect:
Habit-forming, and long-term use may result in
laxative dependence and loss of normal bowel function.
Pharmacological properties:
i) Emodin:
Frangulin: gives on hydrolysis frangula-emodin and rhamnose
Aloe-emodin: in Cascara bark, Senna leaves and Aloes
ii) Rhein: found in rhubarb.
They are reduced form of anthraquinone.
During storage of crude drugs:
Anthranols Anthraquinones (by oxidation).
Tests for identity: Borax test: Extract + borax Green fluorescence
e.g: Chrysarobin:
Use: Keratolytic in cases of psoriasis and skin dermatitis.
3) Oxanthrones: Rarely found
They are derived from two anthrone molecules which may be identical
(e.g. two rhein anthrone moieties .... and called Homo-dianthrone) or
Different (e.g., one rhein anthrone linked to one aloe-emodin-anthrone
moiety……and so called Hetero-dianthrone).
Homo-Dianthrones (Dimers of two similar anthrone moieties)
One of the best known example is senna that contains sennoside
(A or B) derived from molecule of glucose and molecules of rhein-
anthrone. On hydrolysis, sennoside (A or B) yields the
corresponding aglycones sennidine (A or B). Each sennidin
molecule (A or B) is formed of two rhein anthrone moieties.
Hetero-Dianthrones
(Dimers of two different anthrone moieties)
Beside sennoside A and sennoside B, senna contains
sennoside C and sennoside D, which are the glycoside of genins,
named sennidin C and sennidin D, built up of a rhein anthrone +
an aloe-emodin anthrone.