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Questions and Answers
Which extraction method uses gentle heat to enhance solvent efficiency?
Which extraction method uses gentle heat to enhance solvent efficiency?
The decoction method involves boiling the crude drug in a solvent for a specified time.
The decoction method involves boiling the crude drug in a solvent for a specified time.
True
What is the main disadvantage of the maceration extraction method?
What is the main disadvantage of the maceration extraction method?
Not all compounds can be extracted.
The _____ method involves packing the material to be extracted in a column and allowing the solvent to trickle through.
The _____ method involves packing the material to be extracted in a column and allowing the solvent to trickle through.
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Match the following extraction methods with their characteristics:
Match the following extraction methods with their characteristics:
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Which extraction method is specifically suitable for heat-stable, water-soluble constituents?
Which extraction method is specifically suitable for heat-stable, water-soluble constituents?
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Infusion requires the plant material to be soaked in cold solvent.
Infusion requires the plant material to be soaked in cold solvent.
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What is the purpose of the reflux condenser in the Soxhlet extraction method?
What is the purpose of the reflux condenser in the Soxhlet extraction method?
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What is a major disadvantage of the solvent extraction method?
What is a major disadvantage of the solvent extraction method?
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Steam distillation requires separation or filtration steps for effective extraction.
Steam distillation requires separation or filtration steps for effective extraction.
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What method is used to extract volatile oils from plants?
What method is used to extract volatile oils from plants?
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The process of extracting plant constituents by mixing an extract with a less polar solvent is called __________.
The process of extracting plant constituents by mixing an extract with a less polar solvent is called __________.
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Which of the following oils is not obtained from a plant source?
Which of the following oils is not obtained from a plant source?
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Increasing the polarity of the solvent improves the extraction efficiency in solvent extraction.
Increasing the polarity of the solvent improves the extraction efficiency in solvent extraction.
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What happens to the solubility of extracted compounds as the solvent becomes more concentrated?
What happens to the solubility of extracted compounds as the solvent becomes more concentrated?
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What is one disadvantage of the hydrodistillation method?
What is one disadvantage of the hydrodistillation method?
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Hydrodistillation can be performed on any part of the plant without size reduction.
Hydrodistillation can be performed on any part of the plant without size reduction.
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What is the process called when plant material must be subjected to size reduction before hydrodistillation?
What is the process called when plant material must be subjected to size reduction before hydrodistillation?
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The boiling point of turpentine oil is about _____ °C.
The boiling point of turpentine oil is about _____ °C.
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Which hydrodistillation method does not involve keeping water in the bottom of the still?
Which hydrodistillation method does not involve keeping water in the bottom of the still?
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Match the methods of hydrodistillation with their descriptions:
Match the methods of hydrodistillation with their descriptions:
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The process of returning distillation water back to the still is known as cohobation.
The process of returning distillation water back to the still is known as cohobation.
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What is the purpose of an oil separator in the hydrodistillation process?
What is the purpose of an oil separator in the hydrodistillation process?
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Which of the following statements about true alkaloids is correct?
Which of the following statements about true alkaloids is correct?
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All alkaloids are basic in nature.
All alkaloids are basic in nature.
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Name one family of plants that is rich in alkaloids.
Name one family of plants that is rich in alkaloids.
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The sugar part of a glycoside is called the ______.
The sugar part of a glycoside is called the ______.
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Match the following alkaloid types with their characteristics:
Match the following alkaloid types with their characteristics:
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Which statement is true regarding the distribution of alkaloids in plants?
Which statement is true regarding the distribution of alkaloids in plants?
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Glycosides are only found in plant tissues.
Glycosides are only found in plant tissues.
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What role do alkaloids play in plants against herbivores?
What role do alkaloids play in plants against herbivores?
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Study Notes
Plant Extracts and Herbal Preparations
- Extraction procedures are methods for obtaining plant extracts
- Many procedures exist, including:
- Maceration
- Infusion
- Percolation
- Digestion
- Decoction
- Continuous hot extraction
- Solvent-solvent precipitation
- Liquid-liquid extraction
- Distillation
- Specific procedures
Maceration
- Involves placing a crude drug (whole or powdered) in a stoppered container with a solvent and allowing to stand at room temperature for at least 3 days with frequent agitation.
- The mixture is strained, marc (solid material) is pressed, and the liquid is clarified by filtration or decantation.
- Advantage: no degradation of extracted products since no heat is used.
- Disadvantage: not all compounds can be extracted.
Infusions
- The plant material is left to soak in a pre-heated solvent (e.g., hot water) at room temperature.
- The plant debris is separated from the solvent.
- Can be done with or without intermittent stirring.
Digestion
- Similar to maceration but gentle heat is used during extraction.
- Increases solvent efficiency.
Decoction
- Boiling the crude drug in a specified volume of water for a defined time.
- The mixture is then cooled and strained or filtered.
- Suitable for extracting water-soluble and heat-stable constituents.
Percolation
- The material is packed in a column with a filter to prevent solid material escape.
- The solvent (room temperature) is poured on top and allowed to trickle through the plant material.
Continuous Hot Extraction (Soxhlet)
- Uses Soxhlet apparatus to continuously extract plant material with a solvent.
- Plant material is placed in a porous thimble.
- The solvent is boiled and flows through the thimble, extracting plant material, and then collecting in a flask.
- Repetitive process, solvent continuously extracts material.
Solvent-Solvent Precipitation
- Dissolving an extract in a suitable solvent, then mixing with another less polar solvent.
- This causes the precipitation of less soluble components.
Steam Distillation
- Method for extracting volatile oils from plants
- Plant material is mixed with water and heated to boiling.
- The emergent vapors are collected and condensed, separating the oil from the water.
- Can be direct, using steam from a separate generator.
Disadvantages of Distillation
- High temperatures in the presence of water can cause hydrolysis of esters, removal of water soluble compounds, and loss of volatile components.
Volatile Oils
- Obtained by steam distillation or pressing.
- Some types include Musk, from deer; Amber, from whale.
Methods of Volatile Oil Preparation
- Hydrodistillation
- Scarification/Expression
- Extraction with solvents
- Enzymatic hydrolysis
- Supercritical methods
- Method choice depends on plant material condition, oil location, oil amount, and oil constituent nature.
Hydrodistillation (Details)
- The principle is that a mixture of water and immiscible volatile oil boils at a lower temperature than water's boiling point.
- The boiling point of turpentine oil is about 160° C, but when mixed with water and heated, the mixture boils at around 95.6°C.
- The choice of method depends on plant condition and oil location.
- Three types exist.
Water Distillation
- Direct mixing of plant material and water directly in a still pot.
Water and Steam Distillation
- Plant material placed on a perforated screen above the still's bottom to prevent direct water contact.
Direct Steam Distillation
- No water in the bottom of the still
- Steam from separate generator directly passes through plant material.
The Oil Separator
- Separates oil from water after condenser passage.
- Usually done with a Florentine receiver, separating lighter than water oils.
Cohobation (Redistillation of Water)
- The distillation water, containing trace amounts of dissolved volatile oil, is returned to the distillation still to recover the oil.
Alkaloids
- Plant compounds that are basically in nature, derived from amino acids present in plants.
- Contain one or more nitrogen atoms (usually in a heterocyclic ring).
- Have marked physiological action on humans or animals.
Differences from Alkaloids
- Some alkaloids may not be basic.
- The nitrogen atom in some alkaloids might not be part of a heterocyclic ring.
Types of Alkaloids
- True alkaloids: Nitrogen part is part of heterocyclic ring. Derived amino acid.
- Proto alkaloids: Do not have heterocyclic ring with nitrogen but derived from nitrogenous compounds.
- Pseudo alkaloids: Nitrogen is part of heterocyclic ring but not derived from amino acids.
Distribution of Alkaloids
- Found in higher plants (10-25%).
- Dicots tend to have more alkaloids than monocots.
- Families rich in alkaloids (e.g., Apocynaceae, Loganiaceae, Liliaceae, Rubiaceae, Solanaceae, Papaveraceae).
Function of Alkaloids in Plants
- Protective against insects/herbivores (bitter taste).
- Nitrogen source in nitrogen deficiency cases.
- Growth regulators in certain metabolic systems.
- Energy source in carbon dioxide assimilation deficiency.
Glycosides
- Organic compounds with a sugar portion (glycoside) attached to a non-sugar component (aglycone or genin).
- Usually aromatic in nature
- Hydrolyzed by acid, alkali, or enzymes.
Glycosides in Plants
- Occur in small amounts in plants, fungi, and animals.
- Can be used for detoxifying materials.
- Some used for transferring water-insoluble components.
- Act as energy sources, storing harmful products, and aiding in regulation (growth) and coloration.
- Some have antibacterial activity to protect from bacteria and diseases.
- Formed by biochemical reactions transforming water-insoluble compounds into more polar water soluble molecules.
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Description
Test your knowledge on various extraction methods used in herbal medicine. This quiz covers techniques such as decoction, maceration, and Soxhlet extraction, along with their advantages and disadvantages. Understand the specific applications of these methods in extracting plant constituents effectively.
