Plant Glycosides Flashcards
1
Q
glycosides contain a sugar molecule and a non-sugar molecule called an
A
aglycone
2
Q
there are 4 ways in which the sugar and aglycone are linked those include:
A
- C glycosides
- Carbon/carbon bond
- resist acid and base hydrolysis
- O glycosides
- linked by oxygen, stable in acid solution
- acid or enz hydrolysis
- N glycosides
- linked by amino group
- S glycosides
- linked through S atom, usually thiol group
3
Q
what is the most prominant type of glycosides in nature are
A
O-glycosides
4
Q
the sugars found in glycosides are generally
A
- 4-5 carbon sugars
- in alpha or beta form (most beta)
- primarily glucose, can also include rhamnose or galactose
5
Q
the role of the sugar in glycosides is primarily to
A
- aid in absorption
- protect the aglycone moiety from premature metabolism
6
Q
the number of sugars in the molecule impact these three things
A
- polarity, solubility and chromatographic characteristics
7
Q
glycosides are commonly extracted with
A
- dilute alcohol solutions
- freed from contaminants by lead acetate precipitation
- and individual components isolated by preparative chromatography
8
Q
there are 5 groups of glycosides based upon the aglycone group present, these four groups are
A
- cyanogenetic glycosides
- Isothiocyante glycosides
- Antrhacene glycosides
- Phenol glycosides
- steroid glycosides
9
Q
phenol glycosides are further subclassed to include these four groups
A
- simple phenols
- phenolic acids
- flavanoids
- coumarins
10
Q
steriod glycosides include these 4 subcategories
A
- cardenolides
- bufadienolides
- steroid saponins
- triterpene saponins
11
Q
cyanoglycosides have this effect in humans
A
poisonous
12
Q
what are examples of plants that contain cyanide
A
- the seeds of apricots, peaches, cherries and almonds
- cassava
13
Q
what are the glycosides from almonds, cherry bark and linseed that are considered poisonous
A
- amygdalin
- prunasin
- linamarin
14
Q
what are cyanogentic glycosides commonly used for
A
flavouring agents with expectorant properties
15
Q
Anthracene glycosides are commonly used as (2 things) and include the following sources (5)
A
- laxatives or purgatives
- cascara, senna, frangula bark, rhubarb, aloe
16
Q
anthracenes are 3 fused rings of
A
benzene
17
Q
two common glycosides from senna and cascara are
A
sennosides
cascarosides
18
Q
anthracene glycosides are in the
A
- leaves, fruits, barks, rhizomes or juice of plants
19
Q
what is the mecahnism of action of anthrcene glycosides
A
- more active as anthrone glycoside than free anthriquinone
- prevents metabolism of the molecule until it reaches the colon where it gradually releases the anthrone stimulating the intestine to act, in the case of sennosides, defecate
20
Q
what is the most active anthracene
A
sennosides
21
Q
what assay is used to assess anthracene glycosides
A
- qualitative colour test called Borntragers test
- pink red colour obtained when anthraquinone form reacts with alkali
- intensity of colour directly proportional to concentration of anthraquinone
22
Q
what are two analytical challenges in trying to assay senna
A
- separation of sennoside from inactive anthraquinone is difficult, giving higher values
- conversion of the dianthrone to quinone
23
Q
how is the assay for senna performed
A
- extract into ether
- react with magnesium acetate
- measure in spectrophotometer against standard or calibration curve
24
Q
phenolic glycosides include (5)
A
- simple phenols
- tannins
- flavanoids
- coumarins
- lignans
25
simple phenols have wide pharmacological activity including (5 properties)
1. antibacterial
2. anti-inflammatory
3. antipyretic
4. antiemetic
5. antivrial and antirheumatic
26
thymol is isolated from \_\_\_\_\_\_\_\_plant and has this pharmacological effect
rosemarinic acid is isolated from \_\_\_\_\_\_\_\_plant and has this pharmacological effect
* thyme & antibacterial
* lemon balm, rosemary and comfrey & antiviral and anti-inflammatory
27
what is the mechanism of action of rosemarinic acid
* inhibits classical and alternative pathways of complement activation and
* scavenges toxic oxygen from activated polymorphonuclear leucocytes
* antiviral activity - inhibits binding of virus to host cell
28
this group of phenolic glycosides are polymers of simple phenols
tannis
29
tannins can cross link with protein in animal skin to form leather, how is the action of significance for its clinical use
* it provides a barrier to infections for wounds or burns allowing the healing process to occur
30
what are two categories of tannins
* hydrolysable and condensed aka proanthrocyanidins
31
what are some concerns over tannins in herbal teas. Are these concerns valid, why?
* may interfere with drug absorption or minerals/vitamins
* carcinogenic effects
* not valid because regular tea has more tannins than herbal tea
32
flavanoids are the smallest or largest group of naturally occurring phenols
largest
33
most flavanoids exist as C,O,N, or S glycosides
O and C
34
this group of glycosides is found universally in plants
flavanoids
35
flavanoids have these properties (4)
1. antiallergic - Quercetin
2. antispasmotic - Chamomile
3. cardiotonic - hawthorn
4. cerebrovasular - Gingko
36
what is the mechanism of action of the flavanoid quercetin
* inhibition of lipoxygenage, inhibits release of leukotrienes from mast cells
37
this group of phenolic glycosides are Benz - alpha-pyrones
coumarins
38
coumarins have these physiological effects
* inhibt grouwth of bacteria, yeast fungi
* anticoagulant effect
39
Lignans are complex dimeric molecules containing
two phenylpropanoid units linked by a C-c bond
40
what is the best known lignan
podophyllotoxins
41
podophyllotoxins possess this physiological effect
name two podophyllotoxins
* cytotoxic
* etoside and teniposide are used in chemotherapy
42
what are three classes of steroid glycosides
* Cardiac Glycosides
* Steroid Saponins
* Triterpene Saponins
43
steroid glycosides are produces via which pathway
mevalonic
44
cardiac glycosides have this effect
increase pumping action of heart
45
what is the source of the most important cardiac glycoside
* digitalis (foxglove) e.g. digoxin
* also adonis, oleander, and lily of the valley
46
cardiac glycosides contain two aglycones that are cardioactive
* cardiotonic and cardiotoxic glycosides
47
cardiac glycosides can be subcategorized as
* cardenolides and
* bufadienolides
48
cardiac glycosides contain this number of carbons
C23 or C24
49
this is the primary aglycone in cardiac glycosides
cardenolides
50
cardenolides contain this type of lactone ring and Bufadienolides contain this type of lactone ring
* C5
* C6
51
sugar moieties found in cardiac glycosides are (4 - two of which are primarily found)
* digitose\*
* cymerose\*
* glucose
* rhamnose
52
Digitalis glycosides contain this number of glycosides
5
vary with number of OH groups
53
purpea glycosides are also known as
deslanosides
54
what is the activity of glycosides due to
the presence of a lactone ring
55
what is the key element in the attachment of the glycoside to the receptor
carbonyl functional unit of the lactone ring
56
effectiveness of glycoside is depenent upon
sugars which make the glycoside more soluble and assist in binding to cardiac muscle
57
Digitoxin is most widely used because
it is more rapidly absorbed from G.I.T than purpurea glycosides
58
Bufadienolide glycosides are less widely used becaus of
toxicity
59
what plant contains bufadienolides
squill
60
Chemical assays for cardiac glycosides are based on
chromogenic ID tests
61
which reagent is used in TLC separation of digitalis glycosides
Kaiser's reagent
62
this reagent is most commonly used
baljet test detects lactone ring
63
Saponin glycosides are water soluble and have these common characteristics making them easily identifiable
* cause frothing by reducing surface tension
* hemolyze RBCs by forming a complex with cholesterol from the RBC wall
* paralyze fish gills
64
what are the two types of sapogenins (aglycones) in saponin glycosides
* steroidal
* triterpenoidal
65
steroidal saponins are isolated from \_\_\_\_\_\_while triterpene saponins are isolated from\_\_\_\_\_\_\_\_
* monocots such as agave
* dicots such as yams
66
which is the most widely used sapogenin
Diosgenin from mexican yam
67
what are steroidal glycosides commonly used for
precursors for steroidal hormones such as cortisone, estrogens, progesterones etc
68
two main types of triterpenoid saponins include
* tetracyclic triterpenese (trimethylsteroids) C27
* pentacylic triterpenes (C30)
69
pentacyclic triterpenoidal saponin glycosides include these four series of sapogenins. which is the most significante
* ursane
* hopane
* lupane and
* oleanane series\*
70
Oleanane sapogenins are isolated from
senega, primrose, horse chesnut and quillaia ivy
71
triterpenoidal saponins have these physiological effects
* antimitotic
* anti-cancer
* anti inflammatory
* analgesic
* antipyretic
* anti ulcerogenic
* sedative
* cardiac
* antithrombotic
* molluscicidal
* spermicidal
72
aescin from horse chestnut is used for treatment of\_\_\_\_\_\_\_\_\_because of its \_\_\_\_\_\_\_effect
* hemorrhoids
* antagonist effect on edema of blood vessels
73
an important triterpenoid is\_\_\_\_\_\_because of its \_\_\_\_\_\_\_\_\_properties it can be used to treat this parasitic disease
* ginsing
* molluscidal
* schistosomiasis
74
ginsing is sourced from leaves of\_\_\_\_\_\_\_\_\_\_and is widely used because of its\_\_\_\_\_\_\_\_\_effects
* panax ginseng
* protective effects on the body against fatigue and stress, slowing down the degenerative effects of ageing
75
liquorice root contains the glycoside\_\_\_\_\_\_\_\_\_\_which is used to treat\_\_\_\_\_\_\_\_\_\_\_
* glycrrhizin
* ulcers and inflammation
76
what are some common side effects of glycrrhizin
* hypertension
* adreno and mineral corticoid activity
