General Methods for Phytochemical Investigation of Herbal Products

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Questions and Answers

What is a general solvent for many plant constituents, except for most fixed oils?

Alcohol

What is typically necessary for the extraction of organic bases using a water-immiscible solvent?

Basification of the plant material

What is the purpose of ultrasound in the extraction process?

To enhance the extraction process

What is the purpose of a spouted bed unit in extraction?

To remove the pigment layer of the seed-coat Signup and view all the answers

What is the advantage of using a spouted bed unit over solvent extraction?

It produces a less impaired product Signup and view all the answers

What is the purpose of identifying substances like calcium oxalate in drugs?

To detect adulteration Signup and view all the answers

What is the purpose of repeated maceration with agitation in extraction?

To perform the extraction process Signup and view all the answers

What is a Soxhlet extractor used for?

To perform continuous extraction Signup and view all the answers

What is the primary focus of the phytochemical investigation of a plant?

Biological activity of the plant extract Signup and view all the answers

Why is it essential to authenticate the plant material before extraction?

To prevent the examination of material of doubtful origin Signup and view all the answers

What is the primary focus of phytochemical investigation of herbal products?

Understanding the pharmacological properties of plant metabolites Signup and view all the answers

What is the typical procedure for preparing dried plant materials for extraction?

Powdering the material before extraction Signup and view all the answers

What type of plant compounds were previously considered the principal plant drugs in the allopathic system of medicine?

Glycosides and alkaloids Signup and view all the answers

What is the significance of the realization that many plant constituents have medicinal properties?

It has widened the scope of plant metabolites considered worthy of investigation Signup and view all the answers

What is the purpose of investigating the biosynthetic pathways of particular compounds?

To understand the mechanism of compound formation Signup and view all the answers

What is the purpose of extraction of plant material in phytochemical investigation?

To prepare plant material for further analysis and investigation Signup and view all the answers

When is the pharmacological assessment of the separated components typically performed?

Parallel to the characterization of the isolated compounds Signup and view all the answers

What is the purpose of quantitative evaluations in phytochemical investigations?

To measure the amount of compounds present in the plant Signup and view all the answers

What are the non-pharmacological properties of plant metabolites that are of interest to pharmacognosists?

Nutritional and dietetic importance Signup and view all the answers

What is the significance of the observation that many plant constituents have medicinal properties that manifest themselves in subtle ways?

It has widened the scope of plant metabolites considered worthy of investigation Signup and view all the answers

What are the general methods associated with the phytochemical investigation of herbal products?

Extraction, separation, and isolation of constituents Signup and view all the answers

What is the critical state of a substance?

The state where the gas and liquid phases both possess the same density Signup and view all the answers

What is the critical temperature of water?

374°C Signup and view all the answers

What is the primary advantage of using supercritical fluid carbon dioxide for extraction?

It leaves no solvent residues in the product Signup and view all the answers

What is the purpose of adding a modifier to supercritical fluid carbon dioxide?

To make it more polar Signup and view all the answers

What is a characteristic of supercritical fluids?

They have properties intermediate between those of the liquid and gaseous phases Signup and view all the answers

What is the critical pressure of carbon dioxide?

74 atm Signup and view all the answers

Why is supercritical fluid carbon dioxide used for the extraction of labile fragrances and medicinal phytochemicals?

It allows for a low temperature process Signup and view all the answers

What was reported by Cagniard de la Tour in 1822?

The existence of a critical state above which substances do not condense or evaporate Signup and view all the answers

What is the primary advantage of using supercritical fluid extraction in phytochemistry?

It maximizes the extraction of plant constituents Signup and view all the answers

What is the significance of the critical state of a substance?

It is the state where the gas and liquid phases both possess the same density and no division exists between the two phases. Signup and view all the answers

What is the primary advantage of using supercritical fluid carbon dioxide in phytochemistry?

It leaves no solvent residues in the product and has a low environmental impact. Signup and view all the answers

At what temperature and pressure does water exist as a supercritical fluid?

374°C and 220 atmospheres. Signup and view all the answers

What is the primary role of a modifier in supercritical fluid extraction?

To render the supercritical fluid more polar. Signup and view all the answers

Why is supercritical fluid extraction a valuable technique for extracting labile fragrances and medicinal phytochemicals?

Because it allows for the extraction of compounds that are sensitive to heat and decomposition. Signup and view all the answers

What is the critical temperature of carbon dioxide?

31°C. Signup and view all the answers

What is the primary reason why supercritical fluid extraction is of increasing economic interest?

Because it has a lower environmental impact compared to traditional methods. Signup and view all the answers

What is the significance of the density of the gas and liquid phases in the critical state?

They have the same density. Signup and view all the answers

What is the primary advantage of using supercritical fluid extraction for industrial purposes?

It has a lower environmental impact compared to traditional methods. Signup and view all the answers

What is the purpose of using supercritical fluids in phytochemistry?

To extract compounds from plant products. Signup and view all the answers

Study Notes

General Methods in Phytochemical Investigation

The phytochemical investigation of a plant involves four stages: authentication and extraction of the plant material, separation and isolation of the constituents, characterization of the isolated compounds, and investigation of the biosynthetic pathways to particular compounds.
Not all plant compounds are of equal interest; initially, 'active' principles like alkaloids and specific glycosides with pronounced pharmacological properties were prioritized.
However, it is now recognized that many other plant constituents, particularly those associated with herbal medicine, have medicinal properties that manifest in more subtle and less dramatic ways.

Extraction of Plant Material

Plant material should be properly authenticated to avoid wasting time and money on material of doubtful origin.
The choice of extraction procedure depends on the nature of the plant material and the components to be isolated.
Dried materials are usually powdered before extraction, whereas fresh plants can be homogenized or macerated with a solvent like alcohol.
Alcohol is a general solvent for many plant constituents, but may give problems in the subsequent elimination of pigments, resins, etc.

Types of Extraction

Spouted bed extraction: a physical removal of the pigment layer of the seed-coat, yielding a less impaired product than solvent extraction.
Supercritical fluid extraction: uses supercritical fluids to maximize the extraction of plant constituents, with properties intermediate between those of the liquid and gaseous phases.
Supercritical fluid carbon dioxide has an environmental advantage over many common organic solvents and leaves no solvent residues in the product.

Supercritical Fluid Extraction

The critical state occurs when a single substance does not condense or evaporate but exists as a fluid, above a certain temperature and pressure.
For water, the critical conditions are 374°C and 220 atmospheres, and for carbon dioxide, 31°C and 74 atm.
Supercritical fluids can be used to extract a range of materials, including plant products of medicinal, flavouring, and cosmetic interest.

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