Phytochemical Screening

Marwa Al Barazi
2 May 201309:44
EducationalLearning
32 Likes 10 Comments

TLDRThe video script outlines a comprehensive guide to phytochemical screening of plants, focusing on identifying various chemical constituents such as carbohydrates, glycosides, tannins, and alkaloids. The process involves dividing powdered plant material into different sizes and subjecting them to a series of chemical tests. These include the Mish test for carbohydrates, which may yield a violet ring, and the tannin test, which differentiates between hydrolyzable and condensed tannins based on color change. The froth test is used for proteins, while acid and alkaloid tests are conducted using specific reagents like HCL and chloroform. The script also details the preparation of alcohol and aqueous extracts, and the application of tests like the Liebermann and Salkowski tests for alkaloids, and the anthraquinone glycosides test using ammonia. Each test is designed to reveal the presence of specific compounds, contributing to a deeper understanding of the plant's pharmacological activity.

Takeaways
  • 🌿 **Phytochemical Screening Process**: The script describes a detailed procedure for identifying various chemical constituents in plants using chemical tests.
  • 🧪 **Sample Preparation**: Plant samples are categorized into medium, small, and large sizes for different test procedures.
  • 💧 **Aqueous Extract**: A medium-sized portion of the plant is used to create an aqueous extract by boiling it in water.
  • 🔥 **Mish Test**: The presence of carbohydrates is tested by adding Molish reagent and concentrated H2SO4, with a violet ring indicating a positive result.
  • 🍇 **Tannin Test**: Tannins are identified by adding Fe3 to the aqueous extract, with a blue color indicating hydrolyzable tannins and green for condensed tannins.
  • 🌟 **Protho Test**: The test for proteins involves shaking an aqueous extract with 2 ml of HCL and observing froth formation for a positive result.
  • 🍂 **Acid Extract**: An acid extract is prepared for flavonoids testing, where a darker yellow color indicates a positive flavonoid test.
  • 🍾 **Alcohol Extract**: An alcohol extract is made using methanol for alkaloids testing, with the evaporation of the solvent before further tests.
  • 🧬 **Alkaloids Test**: The presence of alkaloids is tested using a capillary tube and filter paper, with a positive result differentiated by color change.
  • 🧪 **Liebermann's Test**: This test for alkaloids involves adding acetic anhydride and concentrated H2SO4, with a reddish-brown ring indicating a positive result.
  • 🔍 **Salkowski Test**: The test for alkaloids also includes the Salkowski test, which requires a reddish-brown ring without a green color in the upper layer for a positive result.
  • 🌹 **Anthraquinone Glycosides Test**: The presence of anthraquinone glycosides is tested with ammonia, where a rose color in the aqueous layer indicates a positive result.
Q & A

  • What is the purpose of phytochemical screening of plants?

    -The purpose of phytochemical screening is to identify and determine the nature of the active chemical constituents in plants, which can help in understanding their pharmacological activity.

  • What are the different sizes of plant portions mentioned in the script?

    -The script mentions three different sizes of plant portions: medium-sized, small-sized, and large-sized portions.

  • How much water is added to the beaker in the script for the aqueous extract preparation?

    -Around 70 mL of water is added to the beaker for the aqueous extract preparation.

  • What is the significance of the violet ring in the Msh test?

    -The appearance of a violet ring in the Msh test indicates the presence of carbohydrates in the aqueous extract of the plant.

  • What does the color change in the tannin test signify?

    -A blue color change signifies the presence of hydrolyzable tannins, while a green color indicates condensed tannins in the aqueous extract.

  • What is observed in a positive protein test using the froth test?

    -In a positive protein test, 1 to 2 cm of persistent froth is observed, which lasts for 2 to 5 minutes.

  • How long is the acid extract left for after adding HCL in the script?

    -The acid extract is left for 20 minutes after adding HCL.

  • What is the purpose of adding methanol to the large size portion of the plant?

    -Methanol is added to the large size portion to prepare the alcohol extract, which is used to identify the presence of different phytochemicals such as alkaloids.

  • What does the color change in the alkaloids test using a capillary tube indicate?

    -A color change in the alkaloids test using a capillary tube indicates the presence of alkaloids in the alcoholic extract of the plant.

  • What are the two tests mentioned for identifying alkaloids in the alcoholic extract?

    -The two tests mentioned for identifying alkaloids are the Liebermann's test and the Salkowski test.

  • What does the appearance of a reddish-brown ring in the Liebermann's test signify?

    -A reddish-brown ring in the Liebermann's test, without a green color in the upper layer, indicates a positive test for alkaloids.

  • How is the presence of anthraquinone glycosides tested in the alcoholic extract?

    -The presence of anthraquinone glycosides is tested by adding 2 ml of the alcoholic extract and 1 ml of ammonia, and observing a rose color in the aqueous layer.

Outlines
00:00
🌿 Phytochemical Screening and Testing of Plant Constituents

This paragraph outlines the process of phytochemical screening for various chemical constituents in plants. It begins with the division of coarse powdered plant material into different sizes for testing. The medium-sized portion is mixed with water and heated, while the preparation for cotton filtration is underway. Several tests are described, including the Mish test for total carbohydrates, the tannin test to differentiate between hydrolyzable and condensed tannins, the froth test for proteins, and the preparation of acid and alcohol extracts for further testing. Each test uses specific reagents and observations, such as the violet ring for the Mish test or the color change for the tannin test, to determine the presence of certain compounds in the plant extract.

05:03
🍷 Alcoholic Extract Preparation and Alkaloid Testing

The second paragraph details the preparation of an alcoholic extract using methanol and the subsequent tests for different classes of plant compounds. After allowing the methanol to extract compounds from the plant material for 30 minutes, the mixture is filtered and the solvent is evaporated. Tests for alkaloids, including the Liebermann and Dragendorff's reagent tests, are conducted using the alcoholic extract. The Liebermann test looks for a reddish-brown ring as a positive result, while Dragendorff's test is positive if the extract turns green. The Salkowski test is also mentioned for further alkaloid identification. Additionally, the presence of anthraquinone glycosides is tested, with a positive result indicated by a rose color in the aqueous layer. Each test is designed to identify specific types of compounds within the plant material.

Mindmap
Keywords
💡Phytochemical screening
Phytochemical screening is the process of identifying and analyzing the chemical constituents of plant materials. It is a crucial step in understanding the medicinal properties of plants and is central to the video's theme. In the script, this process involves various chemical tests to determine the nature of active constituents in plants, which is exemplified by the use of different portions of the plant for testing in beakers, test tubes, and flasks.
💡Chemical constituents
Chemical constituents refer to the various chemical compounds that make up a substance, in this case, plants. Understanding these constituents is vital for determining a plant's pharmacological activity. The script discusses identifying these constituents through chemical tests, highlighting their importance in the context of plant analysis.
💡Carbohydrates
Carbohydrates are a class of biomolecules that include sugars, starches, and cellulose. They are essential components in plants and can be identified through specific chemical tests. In the video, the presence of carbohydrates is tested using the Molish reagent, where a violet ring indicates a positive result, as mentioned in the script.
💡Tannins
Tannins are a group of naturally occurring polyphenols that are known for their astringent properties. They can be categorized into hydrolyzable and condensed tannins. The script describes a test for tannins where the color change (blue for hydrolyzable, green for condensed) indicates the type of tannins present in the plant extract.
💡Pharmacological activity
Pharmacological activity refers to the effects that a substance has on living organisms, particularly in the context of drugs and medications. The video's main theme revolves around determining this activity through the identification of plant constituents. The script outlines various tests that help in understanding how these plant constituents may interact with biological systems.
💡Aqueous extract
An aqueous extract is a liquid substance obtained by extracting components from a plant using water. It is a common method for preparing plant material for analysis. In the script, the aqueous extract is prepared by boiling plant material in water and then filtering it, which is a step towards identifying the plant's chemical constituents.
💡Molisch's test
Molisch's test is a specific chemical test used to detect the presence of carbohydrates. The script describes performing this test by adding Molish reagent and concentrated sulfuric acid to the aqueous extract, with the appearance of a violet ring indicating a positive result for carbohydrates.
💡Tannin test
The tannin test is used to identify the presence of tannins in a plant extract. As detailed in the script, the test involves adding a few drops of Fe3 to the aqueous extract, with a blue color indicating hydrolyzable tannins and a green color indicating condensed tannins.
💡Foam test
The foam test is a method used to detect the presence of saponins, which are compounds that can produce a stable foam when agitated. In the script, a positive test is shown by 1 to 2 cm of persistent foam, which is relevant to the analysis of plant constituents for their potential medicinal properties.
💡Acid extract
An acid extract is obtained by treating plant material with an acid, usually hydrochloric acid (HCL), to extract certain chemical constituents. The script mentions preparing an acid extract and using it for further tests, such as the flavonoids test, which helps in identifying the presence of flavonoids in the plant material.
💡Flavonoids
Flavonoids are a group of plant-derived compounds known for their antioxidant properties and are often associated with the color of plants. The script describes a test for flavonoids where the color change in the presence of NaOH indicates their presence, with a darker yellow color signifying a positive test.
💡Alcohol extract
An alcohol extract is prepared using alcohol, typically methanol, to extract certain chemical constituents that are soluble in alcohol. In the script, an alcohol extract is prepared and used for various tests, including the alkaloids test and the Liebermann's test, to further analyze the plant's chemical makeup.
💡Alkaloids
Alkaloids are a class of naturally occurring organic compounds that mostly contain basic nitrogen atoms. They are often of interest due to their pharmacological effects. The script describes an alkaloids test using a capillary tube and filter paper, where a positive test is indicated by a color change after spraying with Dragendorff's reagent.
💡Anthraquinone glycosides
Anthraquinone glycosides are compounds derived from anthraquinone, which can be found in some plants and are known for their laxative effects. The script mentions a test for these glycosides, where a positive result is indicated by a rose color in the aqueous layer after the addition of ammonia.
Highlights

Phytochemical screening of plants is conducted to determine the nature of active constituents and their pharmacological activity.

Plants are categorized into medium, small, and large size portions for different testing procedures.

Aqueous extracts are prepared by boiling plant material in water and then filtering.

Mish test is used to identify carbohydrates; a violet ring indicates a positive result.

Tannin test differentiates between hydrolyzable and condensed tannins based on the color change to blue or green.

Froth test is positive if 1 to 2 cm of persistent froth is observed, indicating the presence of proteins.

Acid extract preparation involves adding HCL to the test tube and observing any color changes after 20 minutes.

Flavonoids are detected through a color comparison test, where a darker yellow color signifies a positive result.

Alcohol extract is made by adding methanol to the large size portion of the plant and allowing it to steep.

Evaporation of the alcoholic extract is followed by the addition of chloroform and further testing.

Alkaloids are tested using a capillary tube and filter paper, with a positive test showing differentiation from a negative one.

Liverman's test and Liebermann-Burchard test are conducted to identify the presence of steroids and terpenoids, respectively.

Salkowski test is used for the detection of alkaloids, with a reddish-brown ring indicating a positive result.

Anthraquinone glycosides are tested with ammonia, where a rose color in the aqueous layer signifies a positive result.

The process involves multiple chemical tests to screen for various chemical constituents in plants.

Each test has specific reagents and procedures that lead to distinct visual indicators for the presence of certain compounds.

The use of color changes and ring formations is a common theme in identifying the presence of different phytochemicals.

The procedure requires careful observation, precise measurement, and the use of various reagents for accurate results.

The transcript outlines a comprehensive method for the identification and analysis of plant constituents using chemical tests.

Transcripts

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Related Tags
Phytochemical ScreeningChemical ConstituentsCarbohydratesTanninsAlkaloidsPlant AnalysisPharmacological ActivityMish TestFlavonoidsAcid ExtractionChloroform Test