Glycosides Saponins Flashcards
Secondary plant metabolites formed from one or more sugar molecules added to a non-sugar biologically active molecule
Glycosides
That is the sugar and the aglycone in glycosides
Sugar is glucose
aglycone may be
•amino acid derivatives
•steroids
•triterpenes
Types of glycosides
- Saponins
- Glucosinolates
- Cardiac Glycosides (Cardenolides)
- Cyanogenetic Glycosides
- Anthraquinone Glycosides
What is the commonest use of saponins
Combination of hydrophobic terpene with a hydrophillic sugar produces compounds that act as surfactants (detergents)
in Europe the root of Saponaria officinalis (Caryophyllaceae) and in South America the bark of Quillaja saponaria (Rosaceae).
Have high saponins and produce soapy froth upon agitation
Are saponins dangerous
When taken by mouth it is harmless Sarsaparilla, for example, is rich in saponins but is widely used in the preparation of nonalcoholic beverages.
When injected, due to their HAEMOLYTIC properties are highly toxic
Are all haemolytic substances saponins
The fact that a plant contains haemolytic substances is not proof that it contains saponins, and in the species examined by Wall (1961) only about half of those containing haemolytic substances actually contained saponins.
Three properties of saponins
As glycosides they are hydrolysed by acids to give an aglycone (sapogenin) and various sugars and related uronic acids
- Saponins have a high molecular weight and a high polarity and their isolation in a state of purity presents some difficulties.
- Often they occur as complex mixtures with the components differing only slightly from one another in the nature of the sugars present, or in the structure of the aglycone.
What is the aglycone in saponin called
Sapogenin
According to the structure of the sapogenin, what kinds of saponin are recognized
steroidal (commonly tetracyclic triterpenoids)
•pentacyclic triterpenoid types
What is common btn steroidal saponin and pentacyclic triterpenoid
Both of these have a glycosidal linkage at C3 and have a common biogenetic origin via mevalonic acid and isoprenoid units.
compound that contains a cyclopentanoperhydrophenathrene nucleus.
Steroid
What are steroidal alkaloids
distinct subgroup of the steroidal saponins which possess a heterocyclic nitrogen containing ring, giving the compounds basic properties ( e.g. solasodine)
Btn steroidal saponins and pentacyclic triterpenoid which is more widely distributed
pentacyclic triterpenoid
which monocotyledons can you find steroidal saponins
- Dioscoreaceae (e.g. Dioscorea spp.)
- Agavaceae (e.g. Agave and Yucca spp.)
- Smilacaceae (Smilax spp.)
Which dicots are steroidal saponins present
diosgenin in fenugreek (Leguminosae) and of steroidal alkaloids in Solanum (Solanaceae)
well noted for their production of the C27 steroidal alkaloids. These include solasodine and solanidine
Solanum spp
the principal sapogenin used by industry and obtained mostly from yams, from which it is initially isolated.
•Contain a mixture of sapogenins in the glycosidic form.
Diosgenin
Steroidal saponins are of great pharmaceutical importance because…?
sex hormones, cortisone, diuretic, steroids, vitamin D and the cardiac glycosides.
Btn steroidal and pentacyclic which one is common in monocotyledons
Steroidal
What are the dicots pentacyclic steroids are common
- Caryophyllaceae
- Sapindaceae
- Polygalaceae
- Sapotaceae
What are the three groups of pentacyclic saponins
α-amyrin, β-amyrin and lupeol.
How are triterpinoids acid formed in a pentacyclic triterperoid saponin
by replacement of a methyl group by carboxylic acids in positions 4, 17 or 20.
Some usesful tannins
Saponins from yam - Disocorea spp. are the source of steroids used for human hormones
•Birth control pills - most synthetic but some still use natural hormones
•Anti-inflammatory steroids
•Liquorice - Glycyrrhiza glabra produces saponins that possibly help gastric ulcers because they suppress prostaglandins
- Liquorice has long been employed in pharmacy as a
- flavouring agent, demulscent and mild expectorant.
•Glycyrrhizin gel serves as an excellent vehicle for drugs used topically and also has antiviral and anti-inflammatory effects.
herbaceous perennial and has been used as a flavoring agent in foods and medicinal remedies for thousands of years.It’s root has been widely used around the world to treat cough since time immemorial.
Liquorice
Liquorice and glycerrhetinic acid is used to treat…?
rheumatoid arthritis,
•Addison’s disease
•and various inflammatory conditions because of their inhibitory effects of deoxycorticosterone conjugation.
What does high intake of liquorice and glycerrhezinic acid cause
leads to lowered potassium levels, hypertension and muscle weakness
•Glycyrrhizinic acid in liquorice deactivates the protective enzyme in the kidney. Without this enzyme present to break down cortisol, cortisol successfully signals to the kidneys to get rid of potassium and retain sodium and water.
the chief sweet-tasting constituent of Glycyrrhiza glabra root. Structurally, it is a saponin used as an emulsifier and gel-forming agent in foodstuffs and cosmetics.
Glycyrrhizin
Effects of saponins in animals
Highly toxic to fish - used as fish poison (pisicidal)
- Have a bitter acrid taste and cause severe gastric irritation if ingested
- Implicated in livestock poisoning – alfalfa
- Will haemolyze red blood cells if injected into blood stream - because of the detergent properties
- Saponins readily foam in water - Combination of hydrophobic terpene with a hydrophilic sugar produces compounds that act as surfactants (detergents)
- Due to their surface active property they are used as natural surfactants in shower gels, foam baths, lotions, shampoos, etc.
- Have cholesterol lowering activities and so useful in hypercholesterolemia
Three important groups of sulphur containing compounds
- simple hydrocarbon sulphides,
- thiophenes (cyclic examples) and
- glucosinolates.
What species are lachrymators and have pungent odours.
Allium spp
Are Sulphur and nitrogen containing compounds in the mustard family
Glucosinolates
Uses of glucosinolates
Used as condiments e.g., horseradish (responsible for the flavor of cabbages, broccoli, etc)
Many glucosinolates have anti-thyroid and goitre-inducing effects in man
What enzyme hydrolyzes glucosinolates
Myrosinase
What does Enzymatic breakdown of glucosinolates lead to
various bioactive products including isothiocyanates, oxazolidine-2-thiones, nitriles, thiocyanate ion and indole products.
are considered natural protectors of the plants containing them.
•They are produced by higher plants to increase their resistance to predators, microbes and pests.
act as insect repellents, and so are used as bio-fumigants.
•They may be a source of sulphur supply for growing plants
Glucosinolates
Why are plants that contain glucosinolates avoided during feeding of farm animals.
bind iodine and prevent thyroidal gland from iodine uptake.
glycosides that yield hydrogen cyanide or hydrocyanic acid (HCN) as one of the products of hydrolysis.
Cyanogenic
Cyanogenic glycosides derived from the nitrile of ___ acid
of mandelic acid
The Two enzymes involved in cyanogenic glycosides breakdown are?
And when are they brought together
- b-glycosidase releases the sugars
- Hydroxynitrile lyase releases HCN
Only when the cells clash
What is the effect of HCN on ETC
completely inhibits the transfer of electron to oxygen by cytochrome oxidase – final step in the ETS
What type of cyanogenic glycoside is present in Rocaceae
- amygdalin
How can the toxic HCN glycpsides in food be overcome
By selection of cultivars with a low concentration of HCN
• By scientific breeding for a low content
• By developing methods of processing that
reduce the content of unwanted compounds
• By selection of well producing, good tasting
less toxic cultivars to process!
In monocots, anthraquinone derivative are found only in the family___?
Lilaceae, in the form of the unusual C-glycoside barbaloin.
What plants are anthraquinone glycosides absent
absent from the Bryophyta, Pteridophyta and gymnosperms but appear in certain fungi and lichens
What pathways are Natural anthraquinones synthesized
via acetate-malonate pathway or they are derived from shikimate and mevalonate.
What drugs are anthraquinones in
Senna, Aloes, Rhubarb, cochineal etc.
Properties of anthraquinone derivatives
usually orange-red compounds
- They are soluble in hot water or dilute alcohol
- Borntrager’s test is often used for their detection
- When the alcohol powdered drug is treated with ammonia or a pink, red or violet colour is formed
How do you separate Anthraquinone containing a free carboxylic acid group(e.g. rhein) from other anthraquinones
by extraction from an organic solution with sodium bicarbonate
Between Anthranols and anthrones which is soluble in alkali
Anthranols
What are intermediate products between anthraquinones and anthranols which produce anthraquinone on oxidation
Oxanthrones
compounds derived from two anthrone molecules, which may be identical or different
Dianthrones
