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Questions and Answers
What are the two principal types of hydrolysable tannins?
What are the two principal types of hydrolysable tannins?
- Catechin and proanthocyanidin
- Cinnamoyl and flavonoid tannins
- Gallitannins and ellagitannins (correct)
- Quercetin and resveratrol
Gallitannins are primarily composed of which type of acid?
Gallitannins are primarily composed of which type of acid?
- Acetic acid
- Tannic acid
- Hexahydroxy-diphenic acid
- Gallic acid (correct)
Which acid is associated with ellagitannins?
Which acid is associated with ellagitannins?
- Gallic acid
- Caffeic acid
- Hexahydroxy-diphenic acid (correct)
- Citric acid
Which of the following statements regarding hydrolysable tannins is accurate?
Which of the following statements regarding hydrolysable tannins is accurate?
What common characteristic do gallitannins and ellagitannins share?
What common characteristic do gallitannins and ellagitannins share?
What type of linkages unite phenolic acids to a glucose molecule?
What type of linkages unite phenolic acids to a glucose molecule?
Which of the following phenolic acids is specifically mentioned as being part of the structure?
Which of the following phenolic acids is specifically mentioned as being part of the structure?
Which of these compounds is formed from phenolic acids and glucose?
Which of these compounds is formed from phenolic acids and glucose?
What is the structural role of glucose in the formation of tannins?
What is the structural role of glucose in the formation of tannins?
Which of the following correctly describes the composition of tannins?
Which of the following correctly describes the composition of tannins?
What distinguishes 2-non-hydrolysable tannins from hydrolysable tannins?
What distinguishes 2-non-hydrolysable tannins from hydrolysable tannins?
Which of the following correctly describes 2-non-hydrolysable tannins?
Which of the following correctly describes 2-non-hydrolysable tannins?
Which term is synonymous with 2-non-hydrolysable tannins?
Which term is synonymous with 2-non-hydrolysable tannins?
What is a property that 2-non-hydrolysable tannins do NOT exhibit?
What is a property that 2-non-hydrolysable tannins do NOT exhibit?
Which of the following statements about 2-non-hydrolysable tannins is correct?
Which of the following statements about 2-non-hydrolysable tannins is correct?
What is the chemical structure of gallic acid?
What is the chemical structure of gallic acid?
In what situation is gallic acid commonly used?
In what situation is gallic acid commonly used?
What occurs when gallic acid crystallizes?
What occurs when gallic acid crystallizes?
Which property is NOT associated with gallic acid?
Which property is NOT associated with gallic acid?
What type of acid is gallic acid classified as?
What type of acid is gallic acid classified as?
What role do tannin solutions play in the treatment of alkaloidal poisoning?
What role do tannin solutions play in the treatment of alkaloidal poisoning?
Which statement accurately describes the structure formed when tannin interacts with alkaloids?
Which statement accurately describes the structure formed when tannin interacts with alkaloids?
In which scenario would tannin solutions be considered valuable?
In which scenario would tannin solutions be considered valuable?
What is the primary mechanism through which tannin solutions treat alkaloidal poisoning?
What is the primary mechanism through which tannin solutions treat alkaloidal poisoning?
What type of compounds are tannins described as in their action against alkaloids?
What type of compounds are tannins described as in their action against alkaloids?
What is true regarding the presence of tannins in plant species?
What is true regarding the presence of tannins in plant species?
Which statement accurately describes the distribution of tannins?
Which statement accurately describes the distribution of tannins?
In which way is the predominance of tannin types characterized in plants?
In which way is the predominance of tannin types characterized in plants?
Why might one type of tannin predominate in a particular plant part?
Why might one type of tannin predominate in a particular plant part?
What can be inferred about plant species concerning tannin types?
What can be inferred about plant species concerning tannin types?
Flashcards
Tannins
Tannins
Complex molecules formed from phenolic acids like gallic acid and hexahydroxy-diphenic acid linked to a glucose molecule.
Phenolic Acids
Phenolic Acids
Organic acids containing a phenol ring structure, found in tannins and other plant compounds.
Gallic Acid
Gallic Acid
A phenolic acid that is a building block for tannins.
Hexahydroxy-diphenic Acid
Hexahydroxy-diphenic Acid
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Ester Linkages
Ester Linkages
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Hydrolysable Tannins
Hydrolysable Tannins
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Gallitannins
Gallitannins
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Ellagitannins
Ellagitannins
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Classes of tannins
Classes of tannins
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Condensed tannins
Condensed tannins
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Distribution of tannins in plants
Distribution of tannins in plants
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Non-hydrolysable tannins
Non-hydrolysable tannins
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Proanthocyanidins
Proanthocyanidins
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What is the difference between hydrolysable and non-hydrolysable tannins?
What is the difference between hydrolysable and non-hydrolysable tannins?
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What is the common name for non-hydrolysable tannins?
What is the common name for non-hydrolysable tannins?
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Alkaloidal Poisoning
Alkaloidal Poisoning
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Tannin Solutions
Tannin Solutions
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Insoluble Tannate
Insoluble Tannate
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Antidotally Treatment
Antidotally Treatment
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How do tannin solutions work in alkaloidal poisoning?
How do tannin solutions work in alkaloidal poisoning?
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Alkaloidal Precipitant
Alkaloidal Precipitant
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What does 'crystallizes with one molecule of water' mean?
What does 'crystallizes with one molecule of water' mean?
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3,4,5-trihydroxybenzoic acid
3,4,5-trihydroxybenzoic acid
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Study Notes
Tannins
- Tannins are complex plant substances widely distributed in many plant families.
- They are commonly found in leaves, fruits, barks, and stems.
- Chemically, tannins are usually mixtures of polyphenols.
- They are categorized into two classes: hydrolysable and non-hydrolysable tannins.
Hydrolysable Tannins
- These tannins can be broken down (hydrolyzed) by acids or enzymes like tannase.
- They are formed from multiple phenolic acids (like gallic acid and hexahydroxydiphenic acid) linked to a glucose molecule.
- Two main types are gallitannins (gallic acid) and ellagitannins (hexahydroxydiphenic acid).
- Examples of plants containing hydrolysable tannins include rhubarb, hamamelis, cloves, chestnut, pomegranate rind, pomegranate bark, and oak bark.
Non-hydrolysable Tannins (Condensed Tannins)
- Unlike hydrolysable tannins, these don't break down easily into simpler molecules.
- They lack a sugar moiety and related to flavonoid pigments.
- They have polymeric flavan-3-ol structures.
- Treatment with acids or enzymes convert them into red insoluble compounds called phlobaphenes.
- Phlobaphenes give a characteristic red color to some drugs (e.g., red cinchona bark).
Plant Sources Rich in Tannins
- Barks of cinchona, oak, and cinnamon
- Roots/rhizomes of krameria
- Flowers of lime and hawthorn
- Seeds of cocoa and areca
- Fruits of grapes
- Leaves of hamamelis and hawthorn
- Extracts/dried juice of catechu and acacia
Tannin Properties
- Form colloidal solutions in water with an acidic reaction and a puckering/sharp taste.
- Precipitate gelatin and alkaloids.
- Form deep red or greenish-black soluble compounds with ferric salts.
- Also react with potassium ferricyanide and ammonia, forming a deep red color.
- Precipitated by copper, lead, tin, and potassium dichromate.
- In alkaline solutions, many of their derivatives readily absorb oxygen.
- Precipitate proteins from solution and combine with them, making them resistant to protein-digesting enzymes.
Tannin Uses
- Astringent action: Applied to living tissues to reduce/stop bleeding or inflammation; basis for therapeutic applications.
- Tanning leather: Vegetable tanning converts animal hides to leather by affecting pliancy and toughness, also acts as a preservative.
- In inks: Deeply colored compounds with iron salts are used in ink production.
- Reagent in labs: Used to detect gelatin, proteins, and alkaloids.
- Treatment of Poisoning: Solutions are used to deactivate alkaloids.
- Medicine: Used as astringents in the gastrointestinal tract and on skin abrasions (e.g., burns)
- Other preparations: Part of products for hemorrhoids, insect bites/stings, and teething.
Nutgalls
- Excrecence (growth) from twigs of specific oak trees (Quercus infectoria).
- Formed due to infestation by insects (Cynips tinctoria).
- Main component is tannic acid (50-70%).
- Additional components include gallic acid, ellagic acid, starch, and resin.
- Used in tanning, dyeing, and ink production.
Tannic Acid
- Usually extracted from nutgalls.
- Extraction process involves mixing powdered nutgalls with a mixture of ether, alcohol, and water.
- Liquid separates into layers, with aqueous layer containing gallotannin and ethereal layer containing free gallic acid.
- Gallotannin is then evaporated to purify tannic acid.
- Is an astringent.
- Formerly used to treat burns, now mainly for minor wounds or ulcerations.
- Used as a precipitant for alkaloid poisoning.
Gallic Acid
- 3,4,5-trihydroxybenzoic acid.
- Crystallizes with one water molecule.
- Found in nutgalls.
- Can be prepared from tannic acid by hydrolysis.
- Used by ostomates for odor control (with bismuth subgallate).
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Description
Explore the fascinating world of tannins, complex plant substances found in various plant parts like leaves and fruits. Learn about the two main classes of tannins—hydrolysable and non-hydrolysable—along with their chemical compositions and examples of plants that contain them.
