SMK HORLEY METHODIST TELUK INTAN
CHEMISTRY COURSEWORK (962/4) STPM 2017
TITLE: INVESTINGATING ALKALOIDS AS AN IMPORTANT CLASS OF METABOLITES FROM PLANTS.
GROUP MEMBERS’ NAME: CHAN VINZIE (981221-08-6030) CHAN VINKIE (981221-08-6102)
WONG WHUI DHONG (980727-08-6594) KONG WEI YUEN (980302-38-5089)
Content Pages 1.0 Introduction 1.1 Background 1-2 1.2 Literature review 3 2.0 Objectives of research 2.1 Problem statement 3 2.2 Research question 3 3.0 Methodology 3.1 Apparatus& material 4-5 3.2 Procedure 6-8 3.3 Data and observation 9-11 4.0 Bibliography 12
1.0 INTRODUCTION TO TITLE
1.1 BACKGROUND
The alkaloids represent the most diverse group of natural products in living organisms. Alkaloids are a class of naturally occurring organic nitrogen-containing bases
and as an important class of secondary metabolites from plants. This group contains carbon, hydrogen and nitrogen and may also contain oxygen, sulphur and more rarely other elements such as chlorine, bromine and phosphorus.
The name “alkaloid” was first introduced by the German Chemist Carl Friedrich Wilhelm Meissner. Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants and animals. The relationship between alkaloids and other nitrogen-containing compounds is not clear-cut. Some compounds like amino acids, amines peptides, proteins, nucleotides and antibiotics are usually not defined as alkaloids. However, some authors consider alkaloids as a special case of amines.
In general, alkaloids have found use in traditional, modern medicine and drugs. Some plants that containing alkaloids have been used by humans since ancient times for therapeutic and recreational purposes. For instants, the gift (Odyssey of Homer) which given to Helen by the Egyptian queen, a drug bringing oblivion is believed that was an opium-containing drug. A Chinese book on houseplants written in 1st-3rd centuries BC mentioned a medical use of Ephedra and opium poppies. Coca leaves have been used by South American Indians.
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Nowadays, alkaloids had a great impact on the early development of organic chemistry and pharmacy. This respect was the isolation of morphine (principium opii) by Friedrich Wilhelm Sertürner at the beginning of the nineteenth century. The isolation and description of many other pharmacologically active alkaloids soon followed. Alkaloids can be toxic, poisonous and has bitter taste. Many alkaloids dissolve poorly in water but
readily dissolve in organic solvents, such as diethyl ether, chloroform or 1,2-dichloroethane. Caffeine,[156] Most are weak base while some of them such
as theobromine and theophylline are amphoteric.
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2.0 OBJECTIVES
The purpose of this project is to investigate alkaloids as an important class of secondary metabolites from plants. By doing this project, we also can apply basic scientific skills and apply the basic principles and techniques through the investigation.
2.1 PROBLEM STATEMENT
What is the change of the mixture after the Mayer’s reagent is added in the extract of the plant if alkaloid is present?
2.2 LITERATURE REVIEW
According to the website https://en.wikipedia.org/wiki/Alkaloid ,the name "alkaloids" (German: Alkaloide) was introduced in 1819 by the German chemist Carl Friedrich Wilhelm Meißner, and is derived from late Latin root Latin: alkali (which, in turn, comes
from the Arabic al-qalwī – "ashes of plants") and the suffix Greek: -οειδής – "like".[nb 1] However, the term came into wide use only after the publication of a review article by
Oscar Jacobsen in the chemical dictionary of Albert Ladenburg in the 1880s. Alkaloid can be toxic, poisonous and has bitter taste. Many alkaloids dissolve poorly in water but readily dissolve in organic solvents, such as diethyl ether, chloroform or 1,
2-dichloroethane. caffeine, most weak base while some of them such as theobromine and theophylline are amphoteric.
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3.0 METHODOLOGY
APPARATUS
(i) Mortar and pestle (ii) Filter paper (iii) Filter funnel (iv) Conical flask (v) Cotton (vi) Test tube (vii) Stopper
(viii) Evaporating dish (ix) Electronic dish (x) Electronic Balance (xi) Separating Funnel (xii) Oven 4 MATERIAL (i) Soap (ii) Water (iii) Sand
(iv) Ammoniacal Chloroform (v) Sulphuric acid, H2SO4 (vi) Mayer’s reagent
(vii) Organic solvent, e.g. acetone, chloroform, methanol (viii) Dilute acid, eg: hydrochloride, HCl
(ix) Ammonia, NH3 (x) Litmus Paper
(xi) Tobacco Leaves (Nicotiana tabacum, family: Solanaceae) (xii) Pandan Leaves (Pandanus amaryllifolius, family: Pandanaceae) (xiii) Sweet Potato Leaves (Ipomoea batatas,family: Convolvulaceae) (xiv) Papaya Leaves (Carica papaya, family: Caricaceae)
(xv) Hibiscus Leaves (Hibiscus, family: Mallows)
3.2 PROCEDURE
3.2.1 Phytochemical screening for alkaloids
First, clean the mortar and pestle with soap and water to ensure them clean. Then, cut the samples of plants’ part into small pieces and crush it using a mortar and pestle. After that, grind the samples using a circular motion .To aid the crushing, you can add a little bit of fined, clean sand. Furthermore, add about 3 to 5 ml of ammoniacal chloroform to the crushed sample(Ammoniacal chloroform is 1% NH3 chloroform which made of 1ml concentrated ammonia in 1L chloroform). Next, stir and crush further of the mixture to form a loose paste. Then, filter the mixture with a bit of loosely packed cotton using filter funnel. Add 10 to 20 drops of 2M H2SO4 to the filtrate and shake gently to avoid
emulsion forming. Then, wait for the two layers to separate. Lastly, extract the organic
(xiii) (xiv) (xi) (xv) (xii)
layer (top layer) and transfer to a clean test tube as well as add 2 to 3 drops of Mayer’s reagent. If cream precipitate formed or the mixture turns into cloudy, alkaloid is present.
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3.2.2 Solvent Extraction
Firstly, pulverize a large amount of substance (enough for 1 conical flask) to fine powder. The substance can be dry or fresh. Secondly, add organic solvent (e.g.: acetone,
chloroform, methanol) to the substance and keep it stationary for a minimum of three days. Shake the mixtures from time to time. Thirdly, filter the mixture cotton and filter paper respectively. Then, allow the solvent to evaporate by placing it in the fume cupboard for a few days. Next, weight the product. The product is the crude extract. Lastly, record the extract in percentage (%) by mass dry sample, extract of methanol. Efficacy of the extraction may depend on solvent.
3.2.3Acid-Base Extraction
Firstly, extract the dry sample as usual by using ammoniacal chloroform and add 20ml 1M sulphuric acid to the filtrate. Then, transfer the mixture to a separating funnel and shake it. After that extract and keep the aqueous layer as well as add 20 ml 1M sulphuric acid as above to the layer and repeat. Next, test the aqueous layer for presence of alkaloid using Mayer’s reagent as well as extract and keep the aqueous layer. Repeat the
extraction using dilute acid until alkaloids are not detected with Mayer’s reagent. Then, put all the aqueous layers together and add a base to the aqueous layers such as ammonia to neutralize the acid. Furthermore, test the mixture with litmus paper to ensure it is
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neutral or slightly alkaline. Lastly, collect the white solid that float on the top and dry in oven about 50 degrees Celsius or in fume cupboard and weight it. The final product is the refined extract of alkaloids.
3.2.4 Preparation of Mayer’s Reagent
First, dilute 1.36g of HgCl2 with 60ml of H2O. Then, pour the aqueous HgCl2 into 5g of KI in 10 ml of water. Lastly, add water until reach 100ml (dilution).
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3.3
OBSERVATION
(i) Phytochemical Screening for alkaloids of plant parts
Plants samples Observation after the extracts reacted with
Mayer’s reagent
Deduction
1.Tobacco leaves
2.Papaya leaves
4.Pandan leaves
5.Hibiscus leaves
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(ii) Solvent extraction of a selected plant part with high alkaloid content
Plant samples Initial mass of extracts /gram (actual mass) Mass of crude extract after drying/gram (recovered weight) Percentage of recovered alkaloid contained the extracts recovered mass 100% initial mass 1.Tobacco leaves 2.Papaya leaves 3.Sweet potato leaves 4.Pandan leaves 5.Hibiscus leaves
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(iii) Acid-base extraction of alkaloids from the above extracts (only one plant sample is selected)
Actual weight of alkaloid/gram Weight of alkaloid recovered/gram Before drying After drying Colour Percentage of alkaloid recovered =(recovered weight/actual weight) x 100%
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4.0
BIBLIOLOGY
Definition of alkaloid 31/12/2016
https://en.m.wikipedia.org/org/wiki/alkaloid Side effects of alkaloid 3/1/2017
Https://www.drugs.com/sfc/metformin.side-effects-html Acid base extraction 5/1/2017
http://chem.libretexts.org/Core/Analytical_Chemistry/Lab_Techniques/Acid-Base_Extraction
http://medical-dictionary.the free dictionary.com/alkaloid
