Phytochemical screening tests

Phytochemical screening tests

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  Phytochemical Screening Tests By HalavathRamesh Research Scholar Department of Chemistry Loyola College-Chennai University of Madras E-mail:[email protected]
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  Introduction • Phytochemicals arechemical compounds produced by plants. • Challenges in the field phytochemistry including isolating specific compounds and determining their structure and identifying what specific Phytochemical is primarily response in biological activity. • In India Herbal medicines play an important role in the treatment of various diseases by trational methods practiced such as Ayurveda , Unani and Siddha. • Over 2,48,000 species of the higher plants have been identified 12,000 plants are known to have medicinal properties. • The knowledge of pharmacology in essential for understanding action of drugs on animals and human system. • The specific natural products of the primary and secondary metabolites are very important for chemists.
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  Hot maceration methodusing Soxhlet apparatus • Freshly collected plant materials were dried in shade and then coarsly powdered in a blender. • 100g of the coarse powder was extracted successively with 250 ml of various solvents in a soxhlet apparatus for 24 h. All the extracts were filtered through whatman No.41filter paper separately and all the extracts were subjected to qualitative tests for the identification of various phytochemical constituents as per the standard procedures. • The extract were concentrated in a rotary evaporator. The concentrated extracts were used for further analysis.
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  Preliminary Phytochemical Screeningof different extracts The chemical tests for various phytoconstituents present in the extracts were carried out as described below : Test for Alkaloid: The test solution was mixed with little amount of dilute hydrochloric acid and Mayer’s reagent. Formation of a white precipitate indicates the presences of alkaloids. Test for Anthraquinone(Borntrager’s Test): A few drops of magnesium acetate solution were added to the test solution. Pink colour formation shows the presences of anthroquinone.
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  Test for Catechin: Take2ml of test solution, a few drops of Echrlich reagent and concentrate hydrochloric acid were added. Appearance of pink colour indicates the presences of catechin. Test for Coumarin: Take 2ml of test solution, a few drops of alcoholic sodium hydroxide were added.Appearance of yellow colour indicates the presence of coumarin. Test for Flavonoid(Shindo’s test): Take 2 ml of the test solution, a few magnesium turnings and a few drops of concentrate hydrochloric acid were added and boiled for 5 minutes. Appearance of red or orange red colour indicates the presences of flavonoid.
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  Test for Phenol: Take2 ml of the test solution, a few drops of ferric chloride solution were added.Bluish green or red colour indicate the presences of phenol. Test for Quinone: The test solution was treated with a few drops of concentrate sulphuric acid or aqueous sodium hydroxide solution.Colour formation indicate the presence of quinoid compound. Test for Saponin: The test solution was shaken with water. Copious lather formation indicates the presences of saponin.
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  Test for Steroid(Libermann-BurchardTest): Take 2 ml of the test solution , a few drops of chloroform,3-4 drops of acetic anhydride and one drop of concentrate sulphuric acid were added. Appearance of purple colour, which changes to blue or green colour , shows the presences of steroid. Test for Tannin: The test solution was mixed with basic lead acetate solution.Formation of a white precipitate indicates the presences of tannin. Test for Terpenoid(Noller’s Test): The Test solution was warmed with a piece of tin and a few drops of thionyl chloride.Violet or purple colouration indicates the presence of terpenoid.
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  Test for Sugar: Thetest solution was mixed with equal volumes of Fehling’s solution A and Fehling’s solution B and heated. Formation of red colour is the indication of the presence of sugars. Take 2 ml of the test solution, a very small quantity of anthrone and few drops of concentrate sulphuric acid were added and heated. Green to purple colouration indicates the presence of sugars. Test for Glycoside: The extract was mixed with a little anthrone on a watch glass.One drop of concentrate sulphuric acid was added and made into a paste and warmed gently over the water bath.Dark green colouration indicates the presence of glycosides.
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  Test for Xanthoprotein: Tothe test solution, a few drops of concentrate nitric acid and few ml of ammonia were added. Appearance of a red precipitate indicates the presence of xanthoprotein. Test for Fixed oil(Spot test): A small quantity of power/extract was pressed between the filter papers. Formation of grease spot indicate the presence of fixed oils and fats.
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  Bibliography: 1. Anonymous.1990.Phytochemical investigationof certain medicinal plants used in Ayurveda.Central Council for Research in Ayurveda and siddha, New Delhi. 2. Lala PK: Lab manuals of Pharmacognosy CSI Publishers and Distributers,kolkata,1993. 3. Brinda,P., Sasikala,P. And Purushothaman,K.K. 1981.Pharmacognostic studies on merugan kizhangu.Bull.Med.Ethnobot.Res.3:84-96.