GYLCOSIDES. Presented by BAHADUR SINGH HOD Department of Pharm. Sciences Govt. Polytechnic college for Girls Patiala. Glycoside Definition. A substance which on hydrolysis yields a reducing sugar
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Department of Pharm. Sciences
Govt. Polytechnic college for Girls
A substance which on hydrolysis
Glycoside = Broad & general termEmbraces all the many various combinations of sugars & aglyconese.g. Cardiac glycosides, flavonoidglycosides, phenolic glycosides etc
important to determine which isomer has the activityα or βglycosidal bond from an α or βpyranose sugar ringnatural glycosides tend to have β-linkageacid hydrolysis to cleave α or β glycosidesidentify component part of moleculecheck stereochemistry with β-glucosidase
Type of the glycosidic linkage:a- glycosidesb- glycosidesBotanical source:Digitalis glycosidesSenna glycosides.Therapeutic use:Analgesic glycosides.Purgative glycosides.Cardiac glycosides.Chemical nature of the aglycone:Flavone glycosides.Steroidal glycosides.Aldehydic glycosides.MOST COMMONLY USED
1- Effect of acid hydrolysis:
2- Effect of alkaline hydrolysis:
A- Strong alkalis:
B- Mild alkalis:
3- Enzymatic hydrolysis:Split the sugars stepwise starting from the terminal sugars.All plants producing glycosides have enzyme that can hydrolyze these glycosides.Enzymes are specific for the type of glycosidic linkages:Emulsin can hydrolyze b- glycosidesInvertase can hydrolyze a- glycosidesMyrosin can hydrolyze s-glycosides.
Maintenance of neutral conditions:Neutral pH should be assured before and during extraction because:Acidity may result in hydrolysis. This is overcome by addition of CaCO3. Mild alkalinity may sometimes produce racemization.Defatting of fat-rich organs (e.g. seeds) before extraction:High amounts of lipoids hinder glycoside extraction. Defatting is usually carried with petroleum ether
Source: UvaUrsi (Bearberry leaves).
Nature: Primary Phenolic glycoside (monoside).
Uses: Diuretic- Bactericidal.
These include (but are not limited to cardiac glycosides or cardenolides)
Cardenolides are steroidal glycosides exert a slowing and strengthening effect on the failing cardiac muscle.Cardio-Active Glycosides
Steroids in nature exerts powerful action on the cardiac muscle, as a glycoside the sugar moeity is attached to the #3 position of the steroid nucleus2 types of steroid aglyconeCardenolide (C23) – C17 β side chain -- , - unsaturated 5 – membered ringBufadienolide (C24) – homolog of cardenolide, C17 unsaturated 6 – memberedlactone ring - origin prototype – bufalin (Toad – Bufo sp)
To obtain optimum cardiac activity – aglycone must possess an , unsaturated lactone ring on C17 of the steroid nucleus and A/B and C/D on cis – configuration (same side substituent)Sugar – confers the molecule's solubility property, its absorption and distribution in the body (O- hydroxyl group – rapid onset of action)
Description: A perennial herb growing up to 1.5 m from a large white (or red) bulb. It has a single flowering stem, a rosette of large basal leaves, and a dense spike of white flowers.Urginea maritima – (Liliaceae)
A brown ring obtained at the interface indicates the presence of glycosides.
The brown ring obtained is due to the presence of glycone sugar.
Deoxy sugars are sugars that have had a hydroxyl group replaced with a hydrogen. Keller's reagent describes its use to detect the principal components of digitalis: The reaction with this reagent is also known as the Keller-Kiliani reaction. Lack of the Keller-Kiliani reaction suggests the absence of 2-desoxysugar.
1.Glacial acetic acid
2.Ferric chloride solution
3.Concentrated sulphuric acid
B. Materials and Apparatus
1.Treat five ml of each extracts with 2ml of glacial acetic acid containing one drop of ferric chloride solution.
2.Underlay the mixture with 1 ml of concentrated sulphuric acid.
3.A brown ring of the interface indicates a deoxysugar characteristic of cardenolides.
4.A violet ring may appear below the brown ring, while in the acetic acid layer, a greenish ring may form just gradually throughout thin layer.
D. Positive Result
Presence of brown ring on the interface and greenish ring gradually forms on the upper phase.
E. Principle Involved
The brown ring indicates the presence of 2-deoxysugar in the glyconeportion of the cardiac glycoside.
Steroids are known to perform a variety of functions in higher animals. Steroid nucleus is composed of three six member rings and one five member ring.
2. Sulfuric acid
B. Materials and Apparatus
2. Test tubes
1. Add 1ml of the extract to 2ml of chloroform.
2. Carefully add H2SO4. A reddish brown color at the interface indicates
the presence of aglycone portion of cardiac glycoside.
D. Positive Result
Reddish-brown color at the interface
E. Principle Involved
In the Salkowski reaction based method, cholesterol is oxidized in the presence of an excess amount of phosphoric acid and ferric ions to give a reddish brown derivative.
The presence of the aglycone portion of the cardiac glycoside structure is detected. The aglycone part is the portion of the structure where there is the absence of sugar. The change of color into a reddish brown at the interface indicates the aglycone portion of the corchorin.
Lactone is a cyclic ester that can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule. It is identified by a closed ring consisting of two or more carbon atoms and a single oxygen atom, with a ketone group =O in one of the carbons adjacent to the latter. Two classes have been observed in nature - the cardenolides, which have an unsaturated butyrolactone ring and the bufadienolides, which have an a-pyrone ring.
D. Positive Result
Orange to deep red coloration
E. Principle Involved
Reactions due to (-CH2-) group of the lactone ring.
*cardenolide + Baljet's reagent (picric acid +NaOH) → orange or red.
Barfoed's Test is a chemical test used for detecting the presence of monosaccharidesin a solution. Reducing monosaccharidesare oxidized by the copper ion in solution to form a carboxylic acid and a reddish precipitate of copper (I) oxide within three minutes. Reducing disaccharides undergo the same reaction, but do so at a slower rate.
D. Positive result
Brick red precipitate
E. Principle Involved
Cardiac glycosides contain a sugar portion called glycone and a non sugar portion called the aglycone. The sugar present in Corchorin is olitoribiose. If a reducing sugar is present, a brick red precipitate of Copper (II) oxide is form. The reaction will be negative in the presence of disaccharide sugar as they are weaker reducing agents. One can distinguish monosaccharide from disaccharide based on how fast the brick red precipitate is form. Monosaccharide reacts within 2-3 minutes, whereas disaccharide takes longer. The reaction involved is oxidation in acidic medium.
Hetero-Dianthrones: The two anthrone moieties are different. e.g. Sennidins C&D and their corresponding glycosides Sennosides C&D. They are all formed of one Rhein and one Aloe-emodin monomers. The C group are (l)-form while the D group are meso compounds with zero optical rotation.
e.g. Cascarosides A & B. They are both O- and C-glycosides. Each one contain two sugar unites.
e.g. Barbaloin it is formed from the removal of one sugar from Cascarosides.
The major glycoside in Aloes is the C-glycoside Barbaloin.
Barbaloin is primary glycoside in Aloes.
The C-linked glucose at C-10 protect anthrones from oxidation.
Group of organic compounds that form persistent froth when shaken with water.
Saponins cause haemolysis of red blood cells.
The word Soap means Soap like.
Some are used as starting materials for the synthesis of these compounds.
Diosgenin is the main sapogenin used by industry .Significance of Steroidal Saponins
1. Amygdalin ------- mandelonitrile (aglycone)
2. Sambunigrin ------- S - mandelonitrile (aglycone)
amygdalin glucose + prunasin glucose +
mandelonitrile HCN + benzaldehyde
Synonym: wild black cherry, Virginian prune bark, rum or whisky bark
Origin: carefully dried stem bark of Prunusserotina (Rosaceae)
- also known as Prunusvirginiana (wild black cherry tree)
Constituent: prunasin ---partial H+---- HCN
p-coumaric acid, trimethylgallic acid
Use: flavoring vehicle (cough remedies)
sedative expectorant, antitussive, astringent
used for colds, bronchitis, whooping cough
Adverse: fatal poisoning when ingested in large amounts
Black Mustard NF XI (1960) Synonym: brown or chinese mustard, SinapisnigraOrigin: dried ripe seed of Brassicanigra or B. juncea(Brassicaceae)Constituent:sinigrin ---H+---- allylisothiocyanate + KHSO4 + glucose - sinigrin (potassium myronate) - allylisothiocyanate (mustard oil - volatile)Use: local irritant, emetic, externally: rubefacient, pulmonary congestion, rheumatic arthritis commercial: condiment
Flavonoids (or bioflavonoids) (from the Latin wordflavus meaning yellow, their colour in nature) are a class of plantsecondary metabolites.Flavonoids were referred to as Vitamin P (probably due to the effect they had on the permeability of vascular capillaries) from the mid-1930s to early 50s, but the term has since fallen out of use.According to the IUPACnomenclature, they can be classified into:flavones:derived from 2-phenylchromen-4-one (2-phenyl-1,4-benzopyrone) structure (examples:quercetin, rutin).isoflavonoids, derived from 3-phenylchromen-4-one (3-phenyl-1,4-benzopyrone) structureneoflavonoids, derived from 4-phenylcoumarine (4-phenyl-1,2-benzopyrone) structure
The three flavonoid classes above are all ketone-containing compounds, and as such, are flavonoids and flavonols. This class was the first to be termed "bioflavonoids." The terms flavonoid and bioflavonoid have also been more loosely used to describe non-ketonepolyhydroxypolyphenol compounds which are more specifically termed flavanoids, flavan-3-ols (or catechins).
Functions of flavonoids in plantsFlavonoids are widely distributed in plants fulfilling many functions.Flavonoids are the most important plant pigments for flower coloration producing yellow or red/blue pigmentation in petals designed to attract pollinator animals.In higher plants, Flavonoids are involved in UV filtration, symbiotic nitrogen fixation and floral pigmentation.They may act as a chemical messenger or physiological regulator, they can also act as cell cycle inhibitors.Flavonoids secreted by the root of their host plant help Rhizobia in the infection stage of their symbiotic relationship with legumes like peas, beans, clover, and soy. Rhizobia living in soil are able to sense the flavonoids and this triggers the secretion of Nod factors, which in turn are recognized by the host plant and can lead to root hair deformation and several cellular responses such as ion fluxes and the formation of a root nodule.
Potential effects on human healthFlavonoids (specifically flavanoids such as the catechins) are "the most common group of polyphenolic compounds in the human diet and are found in plants Flavonols, the original bioflavonoids such as quercetin, are also found ubiquitously, but in lesser quantities.The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plant compounds (for instance alkaloids) mean that many animals, including humans, ingest significant quantities in their diet. Preliminary research indicates that flavonoids may modify allergens, viruses, and carcinogens, and so may be biological "response modifiers". In vitro studies show that flavonoids also have anti-allergic, anti-inflammatory, anti-microbial, anti-cancer, and anti-diarrheal activities.
Antioxidant activity in vitroFlavonoids (both flavonols and flavanols) are most commonly known for their antioxidant activity in vitro. At high experimental concentrations that would not exist in vivo, the antioxidant abilities of flavonoidsin vitro may be stronger than those of vitamin C and E, depending on concentrations tested.Consumers and food manufacturers have become interested in flavonoids for their possible medicinal properties, especially their putative role in inhibiting cancer or cardiovascular disease. Although physiological evidence is not yet established, the beneficial effects of fruits, vegetables, tea, and red wine have sometimes been attributed to flavonoid compounds.
Potential anti-cancer activityFlavonoids might induce mechanisms that affect cancer cells and inhibit tumor invasion. In preliminary studies, Some cancer researchers proposed that smokers who ate foods containing certain flavonoids, such as the flavan-3-ols (catechins) found in strawberries and green and black teas, kaempferol from brussel sprouts and apples, and quercetin from beans, onions and apples, may have reduced risk of developing lung cancer.
Example flavonoidsQuercetinQuercetin, a flavonoid and more specifically a flavonol, is the aglycone form of other flavonoid glycosides, such as rutin and quercitrin, found in citrus fruit, buckwheat and onions. Quercetin forms the glycosides, quercitrin and rutin, together with rhamnose and rutinose, respectively. Although there is preliminary evidence that asthma, lung cancer and breast cancer are lower among people consuming higher dietary levels of quercetin, the U.S. Food and Drug Administration (FDA), EFSA and the American Cancer Society have concluded that no physiological role exists. The American Cancer Society states that dietary quercetin "is unlikely to cause any major problems or benefits.
EpicatechinEpicatechin may improve blood flow and has potential for cardiac health. Cocoa, the major ingredient of dark chocolate, contains relatively high amounts of epicatechin and has been found to have nearly twice the antioxidant content of red wine and up to three times that of green tea in vitro. In the test outlined above, it appears the potential antioxidant effects in vivo are minimal as the antioxidants are rapidly excreted from the body.Good sources of flavonoids include all citrus fruits, berries, ginkgo biloba, onions (particularly red onion, parsley, pulses, tea(especially white and green tea), red wine, seabuckthorn, and dark chocolate (with a cocoa content of seventy percent or greater).
The citrus bioflavonoids include hesperidin (a glycoside of the flavanonehesperetin), quercitrin, rutin (two glycosides of the flavonolquercetin), and the flavonetangeritin. In addition to possessing in vitro antioxidant activity and an ability to increase intracellular levels of vitamin C, rutin and hesperidin may have beneficial effects on capillary permeability and blood flow. They also exhibit anti-allergy and anti-inflammatory benefits of quercetin from in vitro studies. Quercetin can also inhibit reverse transcriptase, part of the replication process ofretroviruses. The therapeutic relevance of this inhibition has not been established. Hydroxyethylrutosides (HER) have potential for use in the treatment of abnormal capillary permeability, bruising, hemorrhoids, and varicose veins.
Origin: rind of unripe citrus fruits
synonym: hesperetin - 7 - rutinoside or hesperetin ,- 1 -rhamnoside - d - glucoside - methyl eriodictyol
hesperedin --H+ --- hesperetin + rutinose
Use: necessary for the retention of Vit C, catalyzes Vit C and protein to maintain normal capillary resistance (reduce capillary fragility)
- for common colds
Coumarinchemical compound in the benzopyrone chemical class, found in manyplants, notably in high concentration in the tonka bean (Dipteryxodorata), vanilla grass (Anthoxanthumodoratum), sweet woodruff ( Galiumodoratum), mullein (Verbascum spp.), sweet grass (Hierochloeodorata), cassia cinnamon (Cinnamomumaromaticum), melilot(Melilotus ssp.), PanicumClandestinum or 'Deers Tongue'
GYCOSIDAL BITTERS:These are the substances taken before meal to improve the appetite. These glycosides do not belong to the same chemical class but most of the drugs contain monoterpene irridoids with pyran cyclopentane ring. These have the stimulant effect on gustatory nerves in the mouth and lead to increase the gastric juice secretions. The drugs which contain these are:Genatin, Picrorrhiza, Chirata, Quasia, Kalmegh