anthracene glycosides lecture-2012-2013(1)
TRANSCRIPT
![Page 1: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/1.jpg)
ANTHRACENE GLYCOSIDES
• Contains anthraquinone derivatives as their
aglycone component
• Anthraquinones present either in their free
state or as glycosides
• They possess a laxative/cathartic effect
![Page 2: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/2.jpg)
![Page 3: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/3.jpg)
• They are present in:
• Senna /Cassia
• Cascara
• Aloes
![Page 4: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/4.jpg)
DISTRIBUTIONMonocots
• Found in the Liliaceae family
• As C-glycosides
• E.g barbaloin
![Page 5: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/5.jpg)
Dicots
• Occurs in the ff families:
• Rubiaceae
• Leguminosae
• Polygonaceae
• Rhamnaceae
• Ericaceae
• Euphorbiaceae
• Verbenaceae etc
![Page 6: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/6.jpg)
Mode of Action
• Absorbed first in the small intestines
• Hydrolysed in the colon by enzymes to the
pharmacologically active free aglycones
• Released anthraquinones irritate and
stimulate the colon• This enhances its peristaltic movements
leading to purgation
![Page 7: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/7.jpg)
• This usually produces their action in 8-12
hours after administration
• Causes appreciable griping effect
• Generally administered with carminatives
to counteract undesirable effects
![Page 8: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/8.jpg)
Derivatives of anthraquinones
• Anthranols
• Anthrones
• Oxanthrones
• And dianthrones exist
![Page 9: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/9.jpg)
Anthranols and anthrones
• They are reduced anthraquinone
derivatives
• May occur as free or combined as
glycosides
• The 2 are isomeric
• May be converted to the other in solution
![Page 10: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/10.jpg)
![Page 11: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/11.jpg)
Oxanthrones
• These are products obtained from
• Anthraquinones
• Present in cascara bark
![Page 12: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/12.jpg)
• Oxidation of oxanthrones produce
anthraquinones
• Oxidising agents e.g H2O2 may be used
![Page 13: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/13.jpg)
Test for Anthracene glycosides
Borntrager’s Test
• Boil powdered plant material in dil acid
• Filter hot
• Shake filtrate with organic solvent- e.g
chloroform, Ethylacetate, Ether
![Page 14: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/14.jpg)
• Separate organic layer
• Shake with dil ammonia
• Rose pink colour in aqueous layer shows
the presence of free anthraquinones
• Borntrager’s test distinguishes
anthraquinones from anthrones and
anthranols
![Page 15: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/15.jpg)
Modified Borntrager’s test
• Some C-glycosides eg Aloin/barbaloin
do not undergo hydrolysis using only acids or
bases
• Hydrolysis may be caused by using Ferric
chloride/HCl due to oxidative hydrolysis
![Page 16: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/16.jpg)
• Heat powdered drug with solutions of
FeCl3 + HCl on water bath
• Filter whilst hot
• Extract liberated anthraquinone with
organic suitable solvent e.g CHCl3 etc
• Shake organic layer with ammonia
solution
• Rose-pink colour confirms its presence
![Page 17: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/17.jpg)
• Anthrones and anthranols do not give the
test unless they are converted to
anthraquinone
• This is done by oxidation with mild
oxidants such as hydrogen peroxide
![Page 18: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/18.jpg)
Drugs containing Anthracene derivatives
Senna
• Consists of the dried leaflet of Cassia
senna /Alexandrian senna, (C.acutifolia),
Tinnevelly senna (C.angustifolia)
• Family:Leguminosa
• Contains sennoside A & B, C, D
![Page 19: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/19.jpg)
Cascara• The dried bark of Rhamnus purshiana
• Family Rhamnaceae
• Present as O-glycosides/C-glycoside
• Collection made at least one year before
bark is used
• Fresh bark contains emetic principles
• Possesses drastic cathartic action
![Page 20: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/20.jpg)
i) Cascara contains the ff glycosides:
• Cascarosides A & B = barbaloin
• Cascarosides C & D = chrysaloin
![Page 21: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/21.jpg)
Aloes• E.g Aloe vera, A. barbadensis etc
• Common in the liliaceae family
• Aloins are very resistance to hydrolysis
and are not easily hydrolysed to
corresponding anthraquinones
• Oxidative hydrolysis is employed
![Page 22: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/22.jpg)
Effect of storage on the activities of Anthracene glycosides
• Prolonged storage causes oxidation of
anthranols and anthrones to give the
relatively less drastic anthraquinones
• Thus, the degree of the drastic activity of
drugs decreases with time
![Page 23: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/23.jpg)
• Thus anthrones and anthranols are more
potent than their corresponding
oxanthrones
• Oxanthrones in turn are more active
than their corresponding anthraquinones
![Page 24: Anthracene glycosides lecture-2012-2013(1)](https://reader030.vdocuments.net/reader030/viewer/2022021417/588739261a28abc0748b64d9/html5/thumbnails/24.jpg)
Activity of Anthraquinone derivatives
• Anthrones and anthranols > Dianthrones >
Anthraquinones