This document provides an introduction to secondary metabolites called alkaloids, including their definition, classification, properties, chemical tests for identification, and extraction methods. It defines alkaloids as naturally occurring basic compounds containing nitrogen found in plants that often have pharmacological effects. Alkaloids are classified based on their molecular precursors, structures, origins, pharmacology, taxonomy, and as either typical (containing nitrogen in a heterocyclic ring) or atypical alkaloids. Their key properties and chemical tests for identification are also outlined, along with common extraction methods involving the use of alkalis and organic solvents.

1. INTRODUCTION TO SECONDARY
METABOLITES
PREPARED BY
MRS. MEGHA S SHAH
ASSISTANT PROFESSOR, DEPARTMENT OF PAHARMACOGNOSY
AISSMS COLLEGE OF PHARMACY, PUNE
1

2. DEFINITION, CLASSIFICATION, PROPERTIES AND
TEST FOR IDENTIFICATION OF ALKALOIDS
2

3. DEFINITION
Alkaloids —‘as naturally occurring plant compounds having a basic character and
containing at least one nitrogen in a heterocyclic ring.’
With the advent of recent advanced knowledge in the chemistry of various alkaloids two more
inevitable characteristic features were logically and justifiably added to the definition of
alkaloids, namely:
(a) Complex molecular structure, and (b) Significant pharmacological activity.
Furthermore, it was broadly observed that the basic properties of the alkaloids is solely by
virtue of the presence of N-atom embedded into the five-or six- membered ring.
Therefore, the alkaloids are now generally defined as,—‘physiologically active complex
molecular structure basic compounds of plant origin, in which at least one nitrogen atom
forms part of a cyclic system, giving pharmacological action even at very low
concentration’
3

4. CLASSIFICATION 1
Alkaloids are generally classified by their common molecular precursors, based on the
biological pathway used to construct the molecule.
From a structural point of view, alkaloids are divided according to their shapes and
origins. There are three main types of alkaloids:
(1) True alkaloids
(2) protoalkaloids
(3) pseudoalkaloids.
True alkaloids and protoalkaloids are derived from aminoacids, whereas
pseudoalkaloids are not derived from these compounds.
4

5. True Alkaloids
True alkaloids derive from amino acid and they share a heterocyclic ring with nitrogen.
These alkaloids are highly reactive substances with biological activity even in low doses.
All true alkaloids have a bitter taste and appear as a white solid, with the exception of
nicotine which has a brown liquid.
True alkaloids form water-soluble salts.
Most of them are well-defined crystalline substances which unite with acids to form salts.
True alkaloids may occur in plants (1) in the free state, (2) as salts and (3) as N-oxides.
5

6. These alkaloids occur in a limited number of species and families, and are those
compounds in which decarboxylated amino acids are condensed with a non-
nitrogenous structural moiety.
The primary precursors of true alkaloids are such amino acids as L-ornithine, L-
lysine, L-phenylalanine/L-tyrosine, L-tryptophan and L-histidine.
Examples of true alkaloids include such biologically active alkaloids as cocaine,
quinine, dopamine and morphine.
6

7. Protoalkaloids
Protoalkaloids are compounds, in which the N atom derived from an amino acid is not
a part of the heterocyclic.
Such kinds of alkaloid include compounds derived from L-tyrosine and L-tryptophan.
Protoalkaloids are those with a closed ring, being perfect but structurally simple
alkaloids.
They form a minority of all alkaloids.
Hordenine, mescaline and yohimbine are good examples of these kinds of alkaloid.
7

8. The new alkaloids, stachydrine and 4-hydroxystachydrine, derived from Boscia
angustifolia, a plant belonging to the Capparidacea family.
These alkaloids have a pyrroline nucleus and are basic alkaloids in the genus Boscia.
The species from this genus have been used in folk medicine in East and South Africa.
Boscia angustifolia is used for the treatment of mental illness, and occasionally to
combat pain and neuralgia.
8

9. Pseudoalkaloids
Pseudoalkaloids are compounds, the basic carbon skeletons of which are not derived
from amino acids.
In reality, pseudoalkaloids are connected with amino acid pathways.
They are derived from the precursors or post-cursors (derivatives the indegradation
process) of amino acids.
They can also result from the amination and trans-amination reactions of the different
pathways connected with precursors or post-cursors of amino acids.
These alkaloids can also be derived from nonaminoacid precursors.
9

10. The N atom is inserted into the molecule at a relatively late stage, for example, in the
case of steroidal or terpenoid skeletons.
Certainly, the N atom can also be donated by an amino acid source across a trans-
amination reaction, if there is a suitable aldehyde or ketone.
Pseudoalkaloids can be acetate and phenylalanine derived or terpenoid, as well as
steroidal alkaloids.
Examples of pseudoalkaloids include such compounds as coniine, capsaicin,
ephedrine, solanidine, caffeine and theobromine.
10

11. CLASSIFICATION 2
(a) Biosynthetic Classification: In this classification precursor from which the alkaloids in
question are produced in the plant biosynthetically. Therefore, it is quite convenient and also
logical to group together all alkaloids having been derived from the same precursor but
possessing different taxonomic distribution and pharmacological activities.
Examples
(i) Indole alkaloids derived from tryptophan.
(ii) Piperidine alkaloids derived from lysine.
(iii) Pyrrolidine alkaloids derived from ornithine.
(iv) Phenylethylamine alkaloids derived from tyrosine.
(v) Imidazole alkaloids derived from histidine.
11

12. (b) Chemical Classification: It is probably the most widely accepted and common mode of
classification of alkaloids for which the main criterion is the presence of the basic heterocyclic
nucleus (i.e., the chemical entity).
Examples
(i) Pyrrolidine alkaloids e.g., Hygrine;
(ii) Piperidine alkaloids e.g., Lobeline;
(iii) Pyrrolizidine alkaloids e.g., Senecionine;
(iv) Tropane alkaloids e.g., Atropine;
12

13. (v) Quinoline alkaloids e.g., Quinine;
(vi) Isoquinoline alkaloids e.g., Morphine;
(vii) Aporphine alkaloids e.g., Boldine;
(viii) Indole alkaloids e.g., Ergometrine;
(ix) Imidazole alkaloids e.g., Pilocarpine;
(x) Diazocin alkaloids e.g., Lupanine;
(xi) Purine alkaloids e.g., Caffeine;
(xii) Steroidal alkaloids e.g., Solanidine;
(xiii) Amino alkaloids e.g., Ephedrine;
(xiv) Diterpene alkaloids e.g., Aconitine.
13

14. (c) Pharmacological Classification:
 Interestingly, the alkaloids exhibit a broad range of very specific pharmacological
characteristics.
 Perhaps this might also be used as a strong basis for the general classification of the wide-
spectrum of alkaloids derived from the plant kingdom, such as: analgesics, cardio-vascular
drugs, CNS-stimulants and depressants, dilation of pupil of eye, mydriatics, anticholinergics,
sympathomimetics, antimalarials, purgatives, and the like. However, such a classification is not
quite common and broadly known.
14

15. (i) Morphine as Narcotic analgesic;
(ii) Quinine as Antimalarial;
(iii) Strychnine as Reflex excitability;
(iv) Lobeline as Respiratory stimulant;
(v) Boldine as Choleretics and laxatives;
(vi) Aconitine as Neuralgia;
(vii) Pilocarpine as Antiglaucoma agent and miotic;
(viii) Ergonovine as Oxytocic;
(ix) Ephedrine as Bronchodilator;
(x) Narceine as Analgesic (narcotic) and antitussive.
15

16. (d) Taxonomic Classification
 This particular classification essentially deals with the ‘Taxon’ i.e., the taxonomic category. The
most common taxa are the genus, subgenus, species, subspecies, and variety.
 Some ‘phytochemists’ have even gone a step further and classified the alkaloids based on their
chemotaxonomic classification.
 Therefore, the taxonomic classification encompasses the plethora of alkaloids exclusively based
on their respective distribution in a variety of Plant Families, sometimes also referred to as the
‘Natural order’. A few typical examples of plant families and the various species associated
with them are stated below, namely:
16

17. (i) Cannabinaceous Alkaloids: e.g., Cannabis sativa Linn., (Hemp, Marijuana).
(ii) Rubiaceous Alkaloids: e.g., Cinchona Sp. (Quinine); Mitragyna speciosa Korth (Katum, Kratum,
Kutum); Pausinystalia johimbe (K. Schum) (Yohimbe).
(iii) Solanaceous Alkaloids: e.g., Atropa belladona L., (Deadly Nightshade, Belladona);
Brunfelsia uniflorus (Pohl) D. Don (Manaca, Manacan); Capsicum annuum L., (Sweet Peppers, Paprika);
Datura candida (Pers.) Saff. (Borrachero, Floripondio); Duboisia myoporoides R. Br. (Corkwood Tree,
Pituri); Hyoscyamus niger L. (Henbane, Henblain, Jusquaime); Mandragora officinarum L. (Mandrake,
Loveapple); Nicotiana glauca R. Grah. (Tree Tobacco); Seopolia carniolica Jacq. (Scopolia); Solanum
dulcamara L., (Bittersweet, Bitter Nightshade, Felonwood); Withania somniferum (Ashwagandha)
17

18. CLASSIFICATION 3
Atypical alkaloids
These are also known as nonheterocyclic alkaloids and contain nitrogen in aliphatic chain.
18
Typical alkaloids
These are also known as heterocyclic alkaloids and contain nitrogen in heterocyclic ring system.

19. 19

20. 20

21. 21

22. PROPERTIES
Solubility (Physical Properties): The free bases of alkaloids are soluble in organic, non-polar
immiscible solvents but they are either practically insoluble or very sparingly soluble in water.
In contrast, the salts of most alkaloids are soluble in water, relatively less soluble in alcohol
and very sparingly soluble in organic solvents.
E.g atropine sulphate and morphine hydrochloride are freely soluble in water than their
corresponding bases ie atropine and morphine.
Some protoalkaloids and pseudo alkaloids show higher solubility in water. E.g, colchicine is
soluble in alkaline water, acid or water. caffeine is freely soluble in water.
22

23. Chemical Properties: The normal elements present in the alkaloids are carbon, hydrogen and
oxygen but every alkaloid should essentially contain at least one nitrogen atom. They are basic
in reaction, due to the availability of a lone pair of electrons on nitrogen.
The nitrogen in the alkaloids may be primary amine (RNH2) e.g mescaline, as secondary amine
(R2NH) e. ephedrine, tertiary amine (R3N) e.g morphine and quaternary ammonium compounds
(R4N+X) e.g tubocurarine chloride. (The alkaloids containing quaternary bases are only water
soluble.)
23

24. Sensitivity to heat and light (stability): Most of them are susceptible to destruction by heat
and most of them undergo decomposition or degradation by exposure to air and/or light.
They are colorless, crystalline solids with a definite melting point or decomposition range, and
are non-volatile in nature.
Exceptions: Berberine: Yellow in colour. Betanidine: Red in colour.
Nicotine and conine: Liquid and volatile in nature.
Some alkaloids are amorphous and gummy in nature.
24

25. Optical activity: They are usually laevorotatory in nature. A few exceptions are papaverine
which is optically inactive and conine which is dextrorotatory.
Pharmacological activity: Most alkaloids exert some definite pharmacological action. In many
cases, a small quantity of alkaloid brings about a rather pronounced pharmacological effect on
various organs and tissues of animal and human bodies.
Most alkaloids are also chiral molecules which mean they have non-superimposable mirror
images. This results in isomers that have different chemical properties. For example, one isomer
may have a physiological function while the other does not.
25

26. CHEMICAL TESTS
The chemical tests are performed from neutral or slightly acidic solution of drug.
Dragendroff’s Test
Drug solution + Dragendroff ’s reagent (Potassium Bismuth Iodide), formation of
Orangish red colour.
Mayer’s Test
Drug solution + few drops of Mayer’s reagent (potassium mercuric iodide), formation
of creamy-white precipitant.
Hager’s Test
Drug solution + few drops of Hagers reagent (Saturated aq. Solution of Picric acid),
formation of crystalline yellow precipitate.
26

27. Wagner’s Test
Drug solution + few drops of Wagner’s reagent (dilute Iodine solution), formulation of
reddish-brown precipitate.
Tannic Acid Test
Drug solution + few drops of tannic acid solution, formation of buff coloured precipitate.
Ammonia Reineckate Test
Drug solution + slightly acidified (HCl) saturated solution of ammonia reineckate,
formation of pink flocculent precipitate.
27

28. Marme’s Reagent (Potassium-Cadmium Iodide Reagent):
Drug solution + Cadmium Iodide + Potassium Iodide+ water PPT
Scheibler’s Reagent (Phosphotungstic Acid Reagent):
Drug solution + Sodium Tungstate + Disodium Phosphate + water PPT
Sonnenschein’s Reagent (Phosphomolybdic Acid): A 1% (w/v) solution of phosphomolybdic
acid in ethanol.
Bertrand’s Reagent (Silicotungstic Acid): A 1% (w/v) solution of silicotungstic acid in distilled
water.
28

29. Important other specific reactions
Vitali Morin Test: This test is positive for solanaceae family drugs such as Belladona,
Datura, Henbane, Mandrake, Tobacco etc.
Test: Sample alkaloid mixed with fuming nitric acid, evaporated to dryness. Dissolved residue in
acetone and added methanolic solution of KOH. It produced violet colour. It indicates the
presence of tropane group.
Van Urk’s Test: This test is positive for Ergot alkaloid.
Test: Sample reacts with para-dimethyl amino benzaldehyde and dilute sulphuric acid and gives
blue colour. It indicates the presence of indole group especially clavine group of alkaloids.
29

30. Froehd’s Test: This test is positive for opioid alkaloids.
Sample reacts with Froehd’s reagent (sodium molybdate in concentrated sulphuric acid) and
forms brownish black colour due to presence of Isoquinoline group.
Thalloquin Test: This test is positive for Quinine alkaloid.
Cinchona powder react with bromine water in presence of strong ammonia and gives emerald
green colour due to presence of quinoline group.
Rosequin Test: This test is also known as Erythroquinine test. This test is positive for Quinine.
30

31. Test: Sample solution added with dilute acetic acid and few drop of bromine water, added a drop of
solution of potassium ferrocyanide and added a drop of strong ammonia solution. The solution turns
to red colour. In this solution, few ml of chloroform is added then chloroform layer became red
colour.
Murexide Test: positive for purine derivative alkaloids, e.g Caffeine.Test: Caffeine sample is taken in
China dish,added potassium chlorate and dilute HCl. Evaporated to drynesss, produces red colour.
Further expose the China dish on strong ammonia vapour. The red colour is converted into purple or
violet colour. When caffeine reacts with HCl it forms tetramethylalloxanthine which further in
presence of ammonia forms ammonium salt of tetramethylpurpuric acid (Murexide).
31

32. EXTRACTION OF ALKALOIDS
A) stage1:--Powdered material is moistened with water and mixed with alkali like
sodium & potassium carbonate , ammonia, lime. Make a paste with water ,dry ,
repowder.
Reason :--Lime(calcium hydroxide),combines with acid , tannins, and other phenolic
substances and sets free alkaloids.
32

33. B).Stage2:-- extract the free alkaloids by hot continous percolation with chloroform or
any other organic solvents.
Reason:-the free alkaloids dissolve together with other substances soluble in solvent.
C).Stage3:--agitate the chloroform soln. With successive portion of dil.Sulphuric acid
separating the aqueous layer before adding the next portion of acid.
Reason:-the alkaloids are converted into alkaloidal sulphates, which being soluble in
water,pass into aqeous layer.
33

34. D)Stage4:--Make the mixed aqueous liquid alkaline with ammonia, collect the precipitate
that forms, wash with water and dry.
Reason:- Ammonia decomposes the alkaloidal sulphates forming ammonium sulphates ,
soluble in water ,and the free alkaloid which being practically insoluble in water is
precipitated.
34

35. 35

36. DEFINITION, CLASSIFICATION, PROPERTIES AND
TEST FOR IDENTIFICATION OF GLYCOSIDES
36

37. DEFINITION
A glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to
another group via glycosidic bond.
A glycosidic bond is a certain type of chemical bond that joins a sugar molecule to another
molecule.
Specifically, a glycosidic bond is formed between the hemiacetal group of a saccharide (or a
molecule derived from a saccharide) and the hydroxyl group of an alcohol.
A substance containing a glycosidic bond is a glycoside. The glycone and aglycone portions can
be chemically separated by hydrolysis in the presence of acid.
37

38. There are also numerous enzymes that can form and break glycosidic bonds.
The sugar group is known as the glycone and the nonsugar group as the aglycone or genin
part of the glycoside.
The glycone can consist of a single sugar group (monosaccharide) or several sugar groups
(oligosaccharide).The sugars found in glycosides may be glucose and rhamnose
(monosaccharides) or, more rarely, deoxysugars such as the cymarose found in cardiac
glycosides.
In plants glycosides are both synthesized and hydrolysed under the influence of more or less
38

39. PROPERTIES
They are crystalline or amorphous substances that are soluble in water or alcohols and insoluble in
organic solvents like benzene and ether.
They are hydrolysed by water, enzymes and mineral acids.
They are optically active. While glycosides do not themselves reduce Fehling’s solution, the simple
sugars which they produce on hydrolysis will do so with precipitation of red cuprous oxide.
The sugars present in glycoside are of two isomeric forms, that is, α-form and β-form, but all the
natural glycosides contain β-type of sugar.
The aglycone part is soluble in organic solvents like benzene or ether.
39

40. CLASSIFICATION
The glycosides can be classified by the glycone, by the type of glycosidal linkage, and by
the aglycone.
On the Basis of Glycone
If the glycone group of a glycoside is glucose, then the molecule is a glucoside; if it is
fructose, then the molecule is a fructoside; if it is glucuronic acid, then the molecule is a
glucuronide, etc.
40

41. On the Basis of Glycosidic Linkage
1. O-glycosides: Sugar molecule is combined with phenol or –OH group of aglycon, for
example, Amygdaline, Indesine, Arbutin, Salicin, cardiac glycosides, anthraquinone
glycosides like sennosides etc.
2. N-glycosides: Sugar molecule is combined with N of the –NH (amino group) of
aglycon, for example, nucleosides
3. S-glycosides: Sugar molecule is combined with the S or SH (thiol group) of aglycon,
for example, Sinigrin.
4. C-glycosides: Sugar molecule is directly attached with C—atom of aglycon, for
example, Anthraquinone glycosides like Aloin, Barbaloin, Cascaroside and Flavan
glycosides, etc.
41

42. 42

43. 43
O-glycosides C-glycosides
S-glycosides N-glycosides

44. 44
:
Class Examples
Anthraquinone glycosides Senna, Aloe, Rhubarb, etc.
Sterol or Cardiac glycosides Digitalis, Thevetia, Squill, etc.
Saponin glycosides Dioscorea, Liquorice, Ginseng, etc.
Cyanogenetic and Cyanophoric glycosides Bitter almond, Wild cherry bark,
Thiocynate and Isothiocynate glycosides Black mustard
Flavone glycosides Ginkgo
Aldehyde glycosides Vanilla
Phenol glycosides Bearberry
Steroidal glycosides Solanum
Bitter and Miscellaneous glycosides Gentian, Picrrohiza, Chirata, etc.
Coumarin and Furanocoumarin glycoside Cyanidin, malvidin
On the Basis of Aglycone
The various classes according to aglycone moiety are given below

45. On the Basis of Pharmacological activity
Purgative Glycoside : Aloe, senna
Cardiac glycoside: Digitalis, Thevetia
Diuretic: Gokhru
45

46. STAS-OTTO METHOD FOR EXTRACTION
The drug containing glycoside is finely powdered and the powder is extracted by continuous hot
percolation using soxhlet apparatus with alcohol as solvent.
During this process, various enzymes present in plant parts are also deactivated due to heating.
The thermolabile glycosides, however, should be extracted at temperature preferably below 45°C.
The extract is treated with lead acetate to precipitate tannins and thus eliminate nonglycosidal
impurities.
The excess of lead acetate is precipitated as lead sulphide by passing hydrogen sulphide gas
through solution.
The extract is filtered, concentrated to get crude glycosides. From the crude extract, the
glycosides are obtained in pure form by making use of processes like fractional solubility,
fractional crystallization and chromatographic techniques such as preparative thin layer and
column chromatography.
46

47. 47

48. CHEMICAL TESTS
Chemical Tests for Saponin Glycosides
Haemolysis test
A drop blood on slide mixed with few drops of aq. Saponin solution, RBC’s becomes
ruptured in presence of saponins.
Foam test
To 1 gm of drug add 10–20 ml of water, shake for few minutes, formation frothing
which persists for 60–120 sec in presence of saponins.
48

49. Chemical Tests for Steroid and Triterpenoid Glycosides
Libermann burchard test: Alcoholic extract of drug was evaporated to dryness and extracted
with CHCl3, add few drops of acetic anhydride followed by conc. H2SO4 from side wall of
test tube to the CHCl3 extract. Formation of violet to blue colored ring at the junction of two
liquid, indicate the presence of steroid moiety.
Salkowaski test: Alcoholic extract of drug was evaporated to dryness and extracted with CHCl3,
add conc. H2SO4 from sidewall of test tube to the CHCl3 extract. Formation of yellow colored
ring at the junction of two liquid, which turns red after 2 min, indicate the presence of steroid
moiety.
49

50. Antimony trichloride test: Alcoholic extract of drug was evaporated to dryness and extracted
with CHCl3, add saturated solution of SbCl3 in CHCl3 containing 20% acetic anhydride.
Formation of pink colour on heating indicates presence of steroids and triterpenoids.
Trichloro acetic acid test: Triterpenes on addition of saturated solution of trichloro acetic acid
forms colored precipitate.
Tetranitro methane test: It forms yellow colour with unsaturated steroids and triterpenes.
Zimmermann test: Meta dinitrobenzene solution added to the alcoholic solution of drug
containing alkali, on heating it forms violet colour in presence of keto steroid.
50

51. Chemical Tests for Cardiac Glycosides
Keller-kiliani test: To the alcoholic extract of drug equal volume of water and add 0.5 ml of
strong lead acetate solution, shake and filtered. Filtrate extract with equal volume of
chloroform. Chloroform extract evaporate to dryness and obtained residue dissolve in 3 ml of
glacial acetic acid followed by addition of few drops of FeCl3 solution. The resultant solution
transfer to a test tube containing 2 ml of conc. H2SO4. Reddish brown layer is formed, which
turns bluish green after standing due to presence of digitoxose.
51

52. Legal test: To the alcoholic extract of drug equal volume of water and 0.5 ml of strong lead
acetate solution was added, shake and filtered. Filtrate was extracted with equal volume of
chloroform and the chloroform extract was evaporated to dryness. The residue dissolve, add 2
ml of pyridine and sodium nitropruside 2 ml, followed by addition of NaOH solution to
make alkaline. Formation of pink colour in presence of glycosides or aglycon moiety.
3,5-dinitro benzoic acid test: To the alcoholic solution of drug few drops of NaOH followed by
add 2% solution of 3,5-dinitro benzoic acid. Formation of pink color indicates presence of
cardiac glycosides.
52

53. Baljet test: Thick section of leaf of digitalis or the part of drug containing cardiac glycoside, when
dipped in sodium picrate solution, it forms yellow to orange colour in presence of aglycones
or glycosides.
Kedde’s Test: Chloroform extract of drug mixed with 90% alcohol and 2% 3,5-dinitrobenzoic
acid. add 7% NaOH. The solution turns to blue or violet colour. This confirms the presence of
cardenolide aglycone.
53

54. Antimony Trichloride Test: To a powdered drug add solution of antimony trichloride and
trichloroacetic acid then heated the mixture. The solution appears blue or violet colour. This
indicates the presence of Cardenolides and Bufadienolides.
Raymond’s Test: Small quantity of powdered drug dissolved in ethanol. In this solution, 1%
solution of m-dinitrobenzene, methanol and few drops of sodium hydroxide are added.
Violet color confirms the presence of cardiac glycosides. After standing, the violet colour
slowly changes to blue colour. This indicates presence of methylene group at C-21 position
in the lactone ring.
54

55. Test for Cyanogenetic Glycoside:
Sodium Picrate Test: Drug is mixed with dilute sulphuric acid. After the addition of
sodium picrate red colour is produced. This indicates presence of cyanogenetic
glycoside.
Mercuric Acetate Test: Drug solution is mixed with mercuric acetate and forms drug
acetate and mercury is separated out. This confirms the presence of cyanogenetic
glycoside.
55

56. Chemical Tests for Coumarin Glycosides
FeCl3 test: To the concentrated alcoholic extract of drug, add few drops of alcoholic FeCl3
solution. Formation of deep green colour, which turned yellow on addition of conc. HNO3,
indicates presence of coumarins.
Fluorescence test
The alcoholic extract of drug mixe with 1N NaOH solution (one ml each). Development of blue-
green fluorescence indicates presence of coumarins.
56

57. Chemical Tests for Cynophoric Glycoside
Sodium picrate test
Powdered drug moistened with water in a conical flask, add few drops of conc. Sulphuric
acid. Filter paper impregnated with sodium picrate solution followed by sodium carbonate
solution trap on the neck of flask using cork. Formation of brick red colour due to volatile
HCN in presence of cynophoric glycosides takes place.
57

58. Chemical Tests for Flavonoid Glycosides
Ammonia test: Filter paper dipped in alcoholic solution of drug expose to ammonia vapor.
Formation of yellow spot on filter paper.
Shinoda test: To the alcoholic extract of drug magnesium turning and add dil. HCl, formation of
red color indicates the presence of flavonoids. To the alcoholic extract of drug zinc turning
and dil. HCl was added, formation of deep red to magenta color indicates the presence of
dihydro flavonoids.
Vanillin HCl test: Vanillin HCl add to the alcoholic solution of drug, formation of pink colour
due to presence of flavonoids.
58

59. Test for Anthraquinone Glycoside
Brontrager’s Test: This test is performed for the O-glycosides.e.g Senna. Powdered drug is dissolved in few
ml dilute H2SO4 and mixture is boiled. Filtered the solution, filtrate is then extracted with organic solvent
like CHCl3. CHCl3 layer is separated and to that ammonia is added. The ammonia layer gives rose pink
colour. This indicates the presence of O-glycosides.
Modified Brontrager’s Test: This test is performed for the presence of C-glycosides. E.g Aloes. Powdered
drug is mixed with dilute hydrochloric acid and FeCl3. This solution converts C-glycoside to O-
glycoside. Filtered the solution, filtrate is then extracted with organic solvent like CHCl3. CHCl3 layer is
separated and to that ammonia is added. The ammonia layer gives rose pink colour. This indicates the
59

60. DEFINITION, CLASSIFICATION, PROPERTIES AND
TEST FOR IDENTIFICATION OF FLAVANOIDS
60

61. DEFINITION
Flavonoids are polyphenolic compound and vastly available in maximum plant species.
They are generally yellow colored pigments.
They are larger group of glycoside.
They are 2-phenylbenzopyrones derivatives and produce a large number of
physiological activities.
They are largely found in Polygonaceae, Rutaceae, Fabaceae and Rosaceae families.
61

62. Flavonoids are the largest group of
naturally occurring phenols and occur in
free states in the plants as glycosides.
They may be described as a series of
C6-C3-C6 compounds.
62

63. PHYSICAL PROPERTIES
They are crystalline substances with certain melting point.
Catechins, Flavanes, Isoflavanes, Flavanones, Flavanoles are colourless crystals whereas
Flavones, Flavonols, Chalcones are yellow coloured crystals. Anthocyanidins are red in acidic
media and blue in alkaline media.
Anthocyanes are sap pigments. The actual colour of the plant organ is determined by the pH of
the sap. Example: Blue colour of the cornflower and red colour of roses are due to these
glycosides.
Flavonoid glycosides are generally soluble in water and alcohol but insoluble in organic
solvents.
63

64. Aglycone parts of flavonoids are soluble in diethylether, acetone, alcohols etc.
Flavanols are optically active. Flavanones and flavonones are unstable compounds.
Flavonoid O-glycosides are undergoes hydrolysis when treated with acid, alkali.
Rutin is yellow crystalline powder, soluble in alkali but slightly soluble in water.
Rutin on hydrolysis gives quercetin, rhamnose and glucose whereas hesperidin yields
hesperitin, rhamnose and glucose.
Under the UV light flavonoids shows fluorescence of different colours (yellow, orange,
brown, red).
64

65. CHEMICAL PROPERTIES
Chemically flavonoids are based upon a fifteen-carbon skeleton (C15) consisting of two
benzene rings (A and B) linked via a heterocyclic pyrane ring (C).
They occur as aglycones, glycosides and methylated derivatives.
Six-member ring condensed with the benzene ring is either a α-pyrone (flavonols and
flavanones) or its dihydroderivative (flavonols and flavanones).
65

66. The position of the benzenoid substituent divides the flavonoid class into flavonoids
(2-position) and isoflavonoids (3-position).
Flavonols differ from flavanones by hydroxyl group at the 3-position and a C2–C3
double bond.
Flavonoids are often hydroxylated at positions 3, 5, 7, 2, 3’, 4’, and 5’. Methyl ethers
and acetyl esters of the alcohol group are known to occur in nature.
The glycosidic linkage is normally located in flavonoid at positions 3 or 7.
66

67. CLASSIFICATION
Flavanoids
Based on
group
Flavone Flavonol Flavanol Flavanone
Based on place
of B-ring
location
True
flavanoid
Isoflavano
id
Neoflavan
oid
67

68. 1. Based on Groups:
Flavonoids are classified into flavones (e.g. apigenin, and luteolin), flavonols (e.g.
quercetin, kaempferol, myricetin, and fisetin), flavanones (hesperetin,naringenin) and
flavanols 9catechin, epigallocatechin).
68

69. 69
Flavone Apigenin
Apium
petroselinum
Luteolin
Salvia tomentosa
Flavanol Quercetin
Quercus alba
Kaempferol
Pinus sylvestris,
Aloe vera
Myricetin
Rosa damascene
Based
on
Groups

70. 70
Flavanol Catechin
Camellia sinensis
Epigallo catechin
Camellia sinensis
Flavanone Hesperetin
Citrus sinensis
Naringenin
Citrus paradise
Based
on
Groups

71. 2. As per the Place of B-ring location
As per the location of the B-ring, they are three types like true flavonoids, isoflavonoid
and neoflavonoid.
True Flavonoids are derived from 2-phenylchromen-4-one (2-phenyl-l,4 benzopyrone)
structure. True Flavonoids are also known as bioflavonoid due to origin from plants.
Isoflavonoids are derived from 3-phenylchromen- 4-one (3-phenyl-1,4-benzopyrone)
structure and Neo-flavonoids are derived from 4-phenylcoumarine (4-phenyl-1,2-
benzopyrone) structure.
71

72. 72
True Flavonoid Isoflavonoid Neoflavonoid
Apigenin
Apium petroselinum
Luteolin
Salvia tomentosa
Diadzein, Glycitein
Glycine max (Soya bean)
Calophyllolide
Calophyllum Inophyllum
Nivetin
Echinops niveus
Classification of flavonoids based on position of B-ring

73. CHEMICAL TESTS
Shinoda Test: The alcoholic solution of flavone or flavonol when treated with
metallic magnesium (or Zinc) and HCl gives an orange, red or violet colour. This test
is also known as cyanidin reaction.
Lead Subacetate Test: To small quantity of residue, add lead subacetate solution.
Yellow coloured precipitate is formed. Addition of increasing amount of sodium
hydroxide to the residue shows yellow colouration, which decolouration after
addition of acid.
73

74. Wilson’s Reaction: Flavonoids form complexes with boric acid which is not
destroyed by addition of citric acid alcoholic solution (or oxalic acid).
Antimony Pentachloride Test: Alcoholic solution of sample when reacts with
antimony pentachloride the solution produces red or violet colour.
74

75. FUNCTIONS
They act as powerful antioxidant like Quercetin, Xanthohumol, Isoxanthohumol etc.
They control the plant growth. They inhibit and activate plant enzymes.
They having a role in the biochemistry of reproduction.
They have fungicidal properties.
They protect the plant from parasites attack.
They are the pigments of flowers that attract insects for pollination.
They are having significant therapeutic efficacy such as antiviral, antiallergic, antiplatlets,
anti-inflammatory, antitumor etc.
75

76. 76

77. DEFINITION, CLASSIFICATION, PROPERTIES AND
TEST FOR IDENTIFICATION OF TANNINS
77

78. DEFINITION
Tannins are complex, organic, non-nitrogenous, polyphenolic substances of higher
molecular weight plant products, which generally have astringent properties.
These compounds comprise a large group of compounds that are widely distributed in
the plant kingdom.
The term ‘tannin’ denote, substances which have the ability to combine with animal
hides to convert them into leather which is known as tanning of the hide.
78

79. CLASSIFICATION
Tannins
True tannins
Complex
tannin
Condensed
tannin
Hydrolysable
tannin
Ellagitannin
Gallotannin
Pseudo
tannins
79

80. 80

81. CLASSIFICATION
The tannin compounds can be divided into two major groups on the basis of
Goldbeater’s skin test.
A group of tannins showing the positive tanning test may be regarded as true tannins,
whereas those, which are partly retained by the hide powder and fail to give the test,
are called as pseudotannins.
Most of the true tannins are high molecular weight compounds. These compounds are
complex polyphenolics, which are produced by polymerization of simple
polyphenols.
81

82. They may form complex glycosides or remains as such which may be observed
by their typical hydrolytic reaction with the mineral acids and enzymes.
Two major chemical classes of tannins are usually recognized based on this
hydrolytic reaction and nature of phenolic nuclei involved in the tannins
structure.
The first class is referred to as hydrolysable tannins, whereas the other class is
termed as condensed tannins.
82

83. Hydrolysable Tannins
As the name implies, these tannins are hydrolysable by mineral acids or enzymes such as
tannase.
Their structures involve several molecules of polyphenolic acids such as gallic,
hexahydrodiphenic or ellagic acids, bounded through ester linkages to a central glucose
molecule.
On the basis of the phenolic acids produced after the hydrolysis, they are further categorized
under gallotannins composed of gallic acid or ellagitannins which contains
hexahydrodiphenic acid which after intraesterification produces ellagic acid.
83

84. Hydrolysable tannins are sometimes
referred to as pyrogallol tannins as the
components of phenolic acids on dry
distillation are converted to
pyrogallol derivatives.
The hydrolysable tannins are soluble in
water, and their solution produces blue
colour with ferric chloride.
84

85. Nonhydrolysable or Condensed Tannins
Condensed tannins, unlike the previously explained group are not readily
hydrolysable to simpler molecules with mineral acids and enzymes, thus they are also
referred to as nonhydrolysable tannins.
The term proanthocyanidins is sometimes alternatively used for these tannins.
The compounds containing condensed tannins contain only phenolic nuclei which are
biosynthetically related to flavonoids.
85

86. Nonhydrolysable or Condensed Tannins
Catechin which is found in
tannins is flavan-3-o1,
whereas leucoanthocyanidins
are flavan-3,4-diol
structures.
86

87. Nonhydrolysable or Condensed Tannins
These phenolics are frequently linked to carbohydrates or protein molecules to produce
more complex tannin compounds.
When treated with acids or enzymes, they tend to polymerize yielding insoluble red
coloured products known as phlobaphenes.
The phlobaphenes give characteristic red colour to many drugs such as cinchona and
wild cherry bark.
On dry distillation, they yield catechol derivatives. Condensed tannins are also
soluble in water and produces green colour with ferric chloride.
87

88. The families of the plants rich in both of the above groups of tannins include
Rosaceae, Geraniaceae, Leguminosae, Combretaceae, Rubiaceae, Polygonaceae,
Theaceae, etc.
The members of families Cruciferae and Papaveraceae on the other hand are totally
devoid of tannins.
In the plants in which tannins are present, they exert an inhibitory effect on many
enzymes due to their nature of protein precipitation and therefore contribute a
protective function in barks and heartwood.
88

89. 89
Hydrolysable tannins Condense tannins (Non-hydrolysable)
They are known as pyrogallol tannins. They are known as catechol tannins.
They became hydrolysed with the help of acid
or enzyme.
They are resistance to hydrolysis
because glucose moiety is absent.
With 5% FeCl3 solution, it gives bluish
black colour.
With 5% FeCl3 solution, it gives
brownish green colour.
With bromine water it do not form
precipitate.
With bromine water it forms buff
coloured precipitate.
Examples: Arjuna, Tannic acid, Amla,
Myrobalan.
Examples: Ashoka, Black and Pale
Catechu.
Difference between Hydrolysable and Condense Tannins

90. 90
Difference between Gallotannins and Ellagitannins
Gallotannins Ellagitannins
Upon hydrolysis it gives gallic acid. Upon hydrolysis it gives ellagic acid.
It is rapidly soluble in water. It is slowly soluble in water.
Free gallic acid in plant is converted to
gluco-gallotannins.
Present in plant in open and ring forms as
hexa hydroxyl diphenic acid.
Galloyl groups are linked through
depside (polyphenolic compound having
linked with ester bond) bonds.
Galloyl group are linked through C-C
bonds.
More available in Clove, Rhubarb,
Hamamelis.
More available in Eucalyptus,
Promegranate.

91. Pseudotannins
Pseudotannins are simple phenolic compounds
of lower molecular weight. They do not
respond to the tanning reaction of Goldbeater’s
skin test.
E.g of pseudotanninn are Gallic acid,
Chlorogenicacid from Nux vomica and coffee,
or the simple phenolics such as catechin from
cocoa which are abundantly found in plants,
especially in dead tissues and dying cells.
91

92. EXTRACTION AND ISOLATION
Tannin compounds can be easily extracted by water or alcohol.
The general method for the extraction of tannic acid from various galls is either with water-
saturated ether, or with mixture of water, alcohol, and ether.
In such cases, free acids such as Gallic and ellagic acid go along with ether, whereas true
tannin gets extracted in water.
If the drug consists of chlorophyll or pigment, it may be removed by ether.
After extraction, the aqueous and ethereal layers are separately concentrated, dried, and
subjected to further isolation and purification using various separation techniques of
chromatography.
92

93. PROPERTIES
Tannins are colloidal solutions with water.
Non crystalline substance.
Soluble in water (exception of some high molecular weight structures), alcohol, dilute
alkali and glycerin.
Sparingly soluble in ethyl acetate.
Insoluble in organic solvents benzene, ether, chloroform, except acetone.
Molecular weight ranging from 500 to >20,000.
93

94. Oligomeric compounds with multiple structure units with free phenolic groups.
Can bind with proteins and form insoluble or soluble tannin—protein complexes.
They should posses tanning properties.
Tannin with ferric chloride gives blue, black, violet or green colour.
Tannins give precipitate with alkaloids and heavy metals therefore they are used as
antidotes in alkaloidal and heavy metal poisoning.
In aqueous solution tannins produce acidic reaction and heavy metal poisoning.
94

95. CHEMICAL TESTS
Goldbeater’s skin test:
Goldbeater’s skin is a membrane produced from the intestine of Ox. It behaves just like
untanned animal hide. A piece of goldbeater skin previously soaked in 2% hydrochloric
acid and washed with distilled water is placed in a solution of tannin for 5 minutes. It is
then washed with distilled water and transferred to 1% ferrous sulphate solution.
A change of the colour of the goldbeater’s skin to brown or black indicates the presence of
tannin. Hydrolysable and condensed tannins both give the positive goldbeater’s test,
whereas pseudotannins show very little colour or negative test.
95

96. Phenazone Test:
To 5 ml of aqueous solution of tannin containing drug, add 0.5 g of sodium acid
phosphate. Warm the solution, cool, and filter. Add 2% phenazone solution to the
filtrate. All tannins are precipitated as bulky, coloured precipitate.
Gelatin Test:
To a 1% gelatine solution, add little 10% sodium chloride. If a 1% solution of tannin
is added to the gelatine solution, tannins cause precipitation of gelatine from solution.
96

97. Test for Catechin (Matchstick Test):
Catechin test is the modification of the well-known phloroglucinol test for lignin.
Matchstick contains lignin. Dip a matchstick in the dilute extract of the drug, dry,
moisten it with concentrated hydrochloric acid, and warm it near a flame. Catechin in
the presence of acid produces phloroglucinol which stains the lignified wood pink or
red.
97

98. Test for chlorogenic acid:
A dilute solution of chlorogenic acid containing extract, if treated with aqueous
ammonia and exposed to air, slowly turns green indicating the presence of
chlorogenic acid.
Vanillin-hydrochloric acid test:
Drug shows pink or red colour with a mixture of vanillin: alcohol : dilute HCl in the
ratio 1:10:10. The reaction produces phloroglucinol which along with vanillin gives
pink or red colour.
98

99. DEFINITION, CLASSIFICATION, PROPERTIES AND
TEST FOR IDENTIFICATION OF VOLATILE OIL
99

100. DEFINITION
Volatile oils are odorous volatile principles of plant and animal source, evaporate when
exposed to air at ordinary temperature, and hence known as volatile or etheral oils.
These represent essence of active constituents of the plant and hence also known as
essential oils.
In most instances the volatile oil preexists in the plant and is usually contained in some
special secretory tissues, for example, the oil ducts of umbelliferous fruits, the oil cells,
or oil glands occurring in the sub-epidermal tissue of the lemon and orange, mesophyll
of eucalyptus leaves, trichomes of several plants, etc.
100

101. In few cases the volatile oil does not preexist, but is formed by the decomposition of
a glycoside. For example, whole black mustard seeds are odourless, but upon
crushing the seeds and adding water to it a strong odour is evolved.
This is due to allyl isothiocyanate (the main constituent of essential oil of mustard)
formed by decomposition of a glycoside, sinigrin, by an enzyme, myrosin
Glycoside and enzyme are contained in different cells of the seed tissue and are
unable to react until the seeds are crushed with water present, so that the cell contents
can intermingle.
101

102. CLASSIFICATION
Volatile oils are classified on the basis of functional groups present as given in Table
102
Sr no. Groups Example of Drugs
1 Hydrocarbons Turpentine oil
2 Alcohols Peppermint oil, Pudina, Sandalwood oil, etc.
3 Aldehydes Cymbopogon sp., Lemongrass oil, Cinnamon, Cassia and Saffron
4 Ketones Camphor, Caraway and Dill, Jatamansi, Fennel, etc.
5 Phenols Clove, Ajowan, Tulsi, etc.
6 Phenolic ethers Nutmeg, Calamus, etc.
7 Oxides Eucalyptus, Cardamom, and Chenopodium oil
8 Esters Valerian, Rosemary oil, Garlic, Gaultheria oil, etc.

103. PROPERTIES
Volatile oils are freely soluble in ether and in chloroform and fairly soluble in alcohol;
they are insoluble in water.
The volatile oils dissolve many of the proximate principles of plant and animal tissues,
such as the fixed oils and fats, resins, camphor, and many of the alkaloids when in the
free state.
These are chemically derived from terpenes (mainly mono and sesqui terpenes) and
their oxygenated derivatives.
103

104. These are soluble in alcohol and other organic solvents, practically insoluble in
water, lighter than water (Clove oil heavier), possess characteristic odour, have
high refraction index, and most of them are optically active. Volatile oils are
colourless liquids, but when exposed to air and direct sunlight these become darker
due to oxidation.
Unlike fixed oils, volatile oils neither leave permanent grease spot on filter paper
nor saponified with alkalis.
104

105. STORAGE OF VOLATILE OILS
Volatile oils are liable to oxidation on storage in presence of air, moisture, and light.
The oxidation is followed by the change in colour, increase in viscosity, and change in
odour.
Hence, volatile oils must be stored in well-closed completely filled containers and
away from light in cool places.
105

106. PHARMACEUTICAL APPLICATIONS
Volatile oils are used as flavouring agent, perfuming agent in pharmaceutical formulations,
foods, beverages and in cosmetic industries. These are also used as important medicinal agent
for therapeutic purposes like:
1. Carminative (e.g. Umbilliferous fruits) 2. Anthelminitic (e.g. Chenopodium oil)
3. Diuretics (e.g. Juniper) 4. Antiseptic (e.g. Eucalyptus)
5. Counter irritant (e.g. Oil of winter green) 6. Local anesthetic (e.g. Clove)
7. Sedative (e.g. Jatamansi) 8. Local irritant (e.g. Turpentine)
9. Insect repellent (e.g. Citronella) 10.Vitamin A source (e.g. Lemongrass)
106

107. MICRO-CHEMICAL TESTS
Presence of volatile oil in natural drugs can be detected by the following tests.
1. To a thin section of the drug, add an alcoholic solution of sudan III. A red
colour obtained by globules indicate the presence of volatile oil.
2. To a thin section of the drug, add a drop of tincture alkana; red colour
indicates the presence of volatile oil.
107

108. EXTRACTION AND ISOLATION
Extraction by Distillation
The distillation is carried out either by water or steam.
The volatile oils from fresh materials are separated by hydrodistillation, and volatile oils from
air dried parts are separated by steam distillation. However it is better to use fresh materials in
either case.
108

109. Extraction by Scarification/Expression
This method is used for the preparation of oil of lemon, oil of orange, and oil of
bergamot.
These oils are found in large oil glands just below the surface in the peel of the fruit.
The two principal methods of scarification are the sponge and the ecuelle method.
(a) Ecuelle Process:
In this process, the rinds are ruptured mechanically using numerous
pointed projections with a rotary movement and the oil is collected.
109

110. (b)Sponge Process:
In this process the contents of the fruit are removed after making longitudinal or transverse
cut, and the peel is been immersed in water for a short period of time.
Then it is ready for expression.
The operator takes a sponge in one hand and with the other presses the softener peel against
the sponge, so that the oil glands burst open and the sponge absorbs the exuded oil, which is
transferred to a collecting vessel.
The turbid liquid consisting of oil and water is allowed to stand for a short time, whereupon
the oil separates from water and is collected.
The whole of the above process is carried out in cool, darkened rooms to minimize the
harmful effects of heat and light on the oil.
110

111. Extraction by Non-Volatile Solvent
A nonvolatile solvent, for example, a fine quality of either lard or olive oil, is used in this process.
After saturation with the floral oil the lard or olive oil is sometimes used as a flavouring base for
the preparation of pomades, brilliantine, etc., or converted to a triple extract.
In the latter instance the lard or oil is agitated with two or three successive portions of alcohol,
which dissolve the odorous substances.
The mixed alcoholic solutions so obtained constitute the ‘triple extract’ of commerce.
There are three chief methods that come under this. enfleurage, maceration and spraying process.
111

112. Enfleurage:
In this a fatty layer is prepared using lard and the flower petals are spreaded over it, after the
imbibitions is over the fatty layer is replaced with fresh petals.
After the saturation of fatty layer the odorous principles are removed by treating with alcohol
and a triple extract then prepared.
When oil is used as a solvent the flowers are placed on an oil-soaked cloth supported by a
metal grid enclosed in a frame.
Fresh flowers are added as required, and finally the oil is expressed from the cloths. It may
then be used as perfumed oil, or extracted with alcohol to produce a triple extract.
112

113. Maceration:
This is also used to extract the volatile matters of flowers. The lard or oil is heated over a
water bath, a charge of flowers added and the mixture stirred continuously for some time.
The exhausted flowers are removed, pressed, the expressed fluid returned to the hot fat, fresh
flowers, added and the process continued until defined weights of flowers and solvent have
beenused.
Again, a triple extract is prepared by extracting the perfumed lard or oil with alcohol.
113

114. Spraying/Pneumatic method:
In this process a current of warm air is sprayed through a column of the flowers.
Then oil or melted fat is sprayed over this oil-laden air which absorbs and dissolves
most of the perfume, the collected oil or fat is then extracted with alcohol as described
above.
Extraction by Volatile Solvent
In this the flowers are extracted by using the solvent light petroleum and the latter is
distilled off at a low temperature, leaving behind the volatile oil.
114

115. DEFINITION, CLASSIFICATION, PROPERTIES
AND TEST FOR IDENTIFICATION OF RESINS
115

116. DEFINITION
Resins are amorphous mixtures of essential oils and oxygenated products of
terpenes, transparent or translucent solids, semi solid or liquid substances.
They have complex chemical nature and contains large no of carbon atoms.
116

117. CLASSIFICATION
Depending upon the type of the constituents
Resins are of three types:
1. Acid resins examples Colophony contains abietic acid, Copaiba (copaivic and
oxycopaivic acid), Myrrh (Commiphoric acid)
2. Ester resins examples Benzoin (Coniferyl benzoate), Storax (Cinnamyl cinnamate)
3. Resin alcohols examples Peru balsam (Peru resinotannol), Guaiacum resin (Guaic
resinol).
117

118. Depending upon combination with other Constituents:
1. Gum resin: Gum resins are in homogenous combination of gum and resin. These are
always associated with small quantities of other substances like bitter principle,
enzymes and volatile oils etc. It may consist of two or more glycosidal acids in various
proportions and contains trace amount of nitrogen e.g. Myrrh.
2. Oleo resin: When resins are in homogenous combination with volatile oils or oily
liquids, are called oleo resin. They are secreted in schizogenous or schizolysigenous
ducts. Ginger, Capsicum, Turpentine oil.
118

119. 3. Oleo gum resin: These resins are in homogenous combination with volatile oil and
gum. e.g. Asafoetida.
4. Balsam resin: Those oleo resins which contain aromatic acids like benzoic acid or
Cinnamic acid are known as balsam resin e.g. Benzoin.
5. Glycoresin: These are made up of resin along with sugars e.g. Jalap, Ipomoea.
Some resins are complex natural substances not having transpose any specific chemical
property, chemically inert and do not get hydrolysed are known as resenes. Few
examples are asafoetida, colophony etc.
119

120. PROPERTIES
These are amorphous and brittle in nature.
They occur in translucent hard solid form.
The resin softens and finally melted upon heating.
They have specific gravity ranges from 0.9 to 1.25.
When burnt, they produce smoky flame.
They are bad conductor of electricity.
120

121. PROPERTIES
They are soluble in organic solvents like alcohol, ether and chloroform.
They are insoluble in water.
The resin film formed upon drying becomes hard and transparent which is unaffected
by moisture and air.
Majority of resins undergo slow atmospheric oxidation which darkens its colour and
impaired solubility.
121

122. CHEMICAL TEST
Solubility test: Resin dissolves when treated with organic solvents like alcohol, ether
or chloroform etc.
Ignition test: They produces smoky flame upon burning.
HCl test: Drug is treated with hydrochloric acid which forms pink colour, ensures the
presence of resins.
Ferric chloride test: The greenish blue colour develops when drug is treated with
ferric chloride solution. This indicates the presence of resins.
122

123. EXTRACTION AND ISOLATION
Method A Powdered drug
Extract the resin with alcohol
Filter
Concentrate
Concentrate extract an excess of water; shake
Resins get precipitated
123

124. Method B Powdered drug containing Oleo-resin
Percolate the drug with non-polar solvents e.g. Acetone, Chloroform
Non-polar solvent
Steam distillation
Oleo-resin Volatile oils
124

125. QUESTION BANK
1. Explain classification and definition of alkaloids. 5 Marks
2. Explain classification and definition of Glycosides. 5 Marks
3. Explain classification and definition of Tannins. 5 Marks
4. Explain classification and definition of Resins. 5 Marks
5. Explain classification and definition of Flavonoids. 5 Marks
6. Explain classification and definition of Volatile oil. 5 Marks
7. Explain general chemical tests of Alkaloids and glycosides. 5 Marks
8. Explain general chemical tests of Tannins and Resins. 5 Marks
9. Explain general chemical tests of Flavonoids and Volatile oil. 5 Marks
125

126. QUESTION BANK
1. Explain general physical and chemical properties of glycosides and alkaloids. (5)
2. Explain general physical and chemical properties of Tannins and Flavonoids. (5)
3. Explain general physical and chemical properties of Volatile oil and Resins. (5)
4. Explain Alkaloids. 10 Marks
5. Explain Glycosides. 10 Marks
6. Explain Tannins. 10 Marks
7. Explain Volatile oils. 10 Marks
8. Explain Flavonoids. 10 Marks
9. Explain Resins. 10 Marks
126

127. 127