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What is the primary toxic effect of plant glycosides?
What is the primary toxic effect of plant glycosides?
Historically, what was a common application of plant-derived toxins?
Historically, what was a common application of plant-derived toxins?
In what way was ouabain traditionally employed in eastern Africa?
In what way was ouabain traditionally employed in eastern Africa?
What is the source of Ouabain?
What is the source of Ouabain?
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What is the effect of the plant derived toxins in the given text?
What is the effect of the plant derived toxins in the given text?
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What is a key characteristic of cardiac glycosides in terms of their effects on the heart?
What is a key characteristic of cardiac glycosides in terms of their effects on the heart?
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Which statement best describes the source of cardiac glycosides?
Which statement best describes the source of cardiac glycosides?
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What is a typical effect of cardiac glycosides on the heart?
What is a typical effect of cardiac glycosides on the heart?
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Which of the following is a primary concern when considering the clinical use of cardiac glycosides?
Which of the following is a primary concern when considering the clinical use of cardiac glycosides?
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What term is used to collectively describe the class of drugs that are mentioned in the text?
What term is used to collectively describe the class of drugs that are mentioned in the text?
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What kind of ring fusion is characteristic of the aglycone nucleus in cardiac glycosides?
What kind of ring fusion is characteristic of the aglycone nucleus in cardiac glycosides?
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What is the primary action of digoxin immune fab?
What is the primary action of digoxin immune fab?
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If digoxin immune fab binds molecules of digoxin, what is a direct outcome?
If digoxin immune fab binds molecules of digoxin, what is a direct outcome?
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Which of the following is a structural feature associated with the aglycone nucleus of cardiac glycosides?
Which of the following is a structural feature associated with the aglycone nucleus of cardiac glycosides?
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What is the mechanism of action of digoxin immune fab?
What is the mechanism of action of digoxin immune fab?
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What is a notable characteristic of the individual's paintings during the later years of his life?
What is a notable characteristic of the individual's paintings during the later years of his life?
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Which of the following best describes the individual's state of mental health based on the provided information?
Which of the following best describes the individual's state of mental health based on the provided information?
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What is implied about the individual's mental state, given his final artistic period?
What is implied about the individual's mental state, given his final artistic period?
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Besides depression and insanity, what other significant mental health-related problem is mentioned in the individual's history?
Besides depression and insanity, what other significant mental health-related problem is mentioned in the individual's history?
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What specific color is explicitly mentioned as being characteristic of the individual's paintings during his last years?
What specific color is explicitly mentioned as being characteristic of the individual's paintings during his last years?
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What are some of the reasons critics have attributed to Van Gogh's aberrations?
What are some of the reasons critics have attributed to Van Gogh's aberrations?
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What is xanthopsia?
What is xanthopsia?
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What is a potential side effect of digitalis intoxication that Van Gogh might have experienced?
What is a potential side effect of digitalis intoxication that Van Gogh might have experienced?
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Which of the following did critics NOT ascribe as a cause of Van Gogh's visual aberrations?
Which of the following did critics NOT ascribe as a cause of Van Gogh's visual aberrations?
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According to the content, what are 'coronas'?
According to the content, what are 'coronas'?
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Which plant family is specifically mentioned as a source of squill?
Which plant family is specifically mentioned as a source of squill?
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What is the primary plant part of Urginea maritima used to produce squill?
What is the primary plant part of Urginea maritima used to produce squill?
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What is the therapeutic application of the compounds found in squill?
What is the therapeutic application of the compounds found in squill?
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The text identifies ‘Scillarins’ primarily as a:
The text identifies ‘Scillarins’ primarily as a:
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Which family is Urginea maritima classified under?
Which family is Urginea maritima classified under?
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Study Notes
Cardiac Glycosides
- Cardiac glycosides are a class of naturally occurring drugs, impacting the heart with both beneficial and toxic effects. They are plant-derived, acting specifically on the heart.
Historical Use
- Traditionally used as arrow poisons in Eastern Africa for hunting and warfare.
- Used to assassinate people.
Modern Use
- Treating congestive heart failure (dropsy/edema).
- Treating atrial fibrillation and irregular heartbeats (HR).
- Diuretic agent.
Sources (examples)
- Digitalis lanata: (Total glycosides, 1.5%), primary glycosides are Lanatosides A-E and digoxin.
- Digitalis purpurea: (Total 0.5%), primary glycosides are Purpural glycosides A, B & E, digitoxin, gitoxin and gitraloxin.
Pharmacology and Mode of Action
- Act directly or indirectly on the failing heart.
- Increase contractility (positive inotropic effect) of heart muscle.
- Slow heart rate (antiarrhythmic effect) by affecting atrioventricular conduction.
- Have a diuretic effect on the kidney.
Mechanism of Action
- Inhibit the sodium pump (Na+/K+ adenosine triphosphatase).
- Accumulate intracellular sodium, triggering sodium/calcium exchange.
- Increase calcium levels in heart cells, enhancing contractile force.
- Also stimulate the vagus nerve, so decreasing the heart rate.
Chemical Structure - Aglycone Moiety
- Steroidal nucleus.
- Unsaturated lactone ring attached to C-17.
- A tertiary β-hydroxyl group attached to C-14.
- Cis-junction of rings C/D and A/B is essential for cardiac activity.
- A/B cis fused rings, are more potent than A/B trans.
SAR-Aglycone Moiety
- Oxygen substitution in the steroidal nucleus influences distribution and metabolism (e.g., more -OH groups cause quicker action and removal from the body.)
- Replacing -OH groups at C-3 or C-14 with Hydrogen atoms reduces potency.
- β orientation of C-17 is necessary for activity. 17 α-cardenolides are inactive.
Structure-Activity Relationship (SAR)
- Cardioactivity depends on the aglycone moiety.
- Pharmacokinetic behavior is influenced by the glycone moiety (sugar). This affects aspects such as polarity, onset of action and excretion.
SAR-Sugar Moiety
- The sugar moiety is generally inactive but when attached to the steroid moiety, it affects the activity and pharmacokinetic behavior.
- Free aglycones are less potent than their glycosides.
- Sugar type and number influence potency.
- Digoxin, with 6-deoxy sugars is usually more potent than its 6-CH2OH counterpart.
Digitalis Glycosides - Source (examples)
- D lanata: Primary glycosides are Lanatosides A-E and digoxin.
- D purpurea: Major glycosides are A, B, E, digitoxin, gitoxin and gitaloxin.
Cardiac Glycosides from Oleander
- Nerium oleander's active part are its leaves, sourced from the Apocynaceae family.
- Contains cardioactive compounds like Thevetioside, and Oleandrin.
- These are highly toxic and even small amounts produce symptoms like skin rash, blurred vision, nausea, abdominal pain, etc.
- Yellow oleander (Thevetia peruviana) is rich in Thevetin A.
Bufadinolides
- Less widely distributed in nature than cardenolides.
- These are found in Liliaceae and Ranunculaceae
- Rarely used therapeutically as cardioactive drugs.
Squill
- Dried sliced bulbs (used part) of Urginea maritima.
- Liliaceae family.
- Contains scillarins (like scillaren A and proscillaridin A).
Toad Venom Posioning
- Similar to digitalis toxicity, carrying high mortality.
- Venom gland of cane toads contains significant amounts of cardiac glycosides.
Comparison between Digoxin/Digitoxin
- Digoxin:
- Usually administered orally.
- Shorter onset of action.
- Shorter half-life in the bloodstream.
- Eliminated via kidney.
- Digitoxin:
- Usually administered orally.
- Longer onset of action.
- Longer half-life in the bloodstream.
- Eliminated via liver.
Digoxin Toxicity and Antidote
- Digoxin immune fab (digoxin antibody) binds to and removes digoxin from the body.
Mechanism of Action and Side Effects (general)
- Cardiac glycosides inhibit the Na+/K+ ATPase enzyme.
- Side effects are variable, but some common ones are visual disturbances, nausea, vomiting, anxiety, and potentially fatal arrhythmias.
- Preferred treatments: ACE inhibitors, beta blockers.
- Contraindications: Ventricular fibrillation.
Xanthopsia (Yellow Vision)
- Possible symptom of digoxin intoxication.
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Description
Test your knowledge on the effects, sources, and applications of plant glycosides and cardiac glycosides. This quiz covers their historical uses, primary concerns in clinical contexts, and key characteristics. Perfect for students studying pharmacology or toxicology.
