Alkaloids

Pharmacognosy and phytochemistry
Sem-4

1. ALKALOIDS
Name:-Gourav Singh
Department of Pharmacognosy-ii

2. INTRODUCTION
Introduced:-W. Meissener
Century:-19
th
Define:-An alkaloid is a nitrogenous organic molecule
that has a pharmacological effect on humans and
animals.
Derivatives:-Amino acid
Designate:-Natural substances reacting like base.
Found:-Secondary metabolite plants, fungi
Taste:-Very bitter taste
Kingdom:-Vegetable
Used:-medicine as analgesic (pain reliever) or
anesthetics.
2

3. Physical
Properties
Properties Description
Condition Most alkaloids are crystalline solids.
Fewalkaloids are amorphous solid
e.g. emetine.
Some are liquids that are either:
Volatile e.g. nicotine or non-volatile
e.g. pilocarpine
Color Majorityof alkaloids are colorless
but some are colored e.g. Colchicine
and berberine are yellow, canadine
is orange
Solubility oBoth alkaloidalbases and their salts
are soluble in alcohols.
oGenerally, bases are soluble in
organic solvents and insoluble in
water
3

4. Chemical
Properties
Nitrogen:-
Oxygen:-
Types of amines Digramatic Examples
Primaryamines ??????−????????????
2 Norephedrine
Secondary amines ??????
2−???????????? Ephedrine
Tertiary amines ??????
3−?????? Atropine
Quaternary amine ??????
4−?????? D-Tubocurarine
AlkaloidsContainsNature Example
Most
alkaloids
Oxygen Solid Atropine
Some
alkaloids
Free from
oxygen
Liquid Nicotine,
Coniine
4

5. Chemical
Properties
Basicity:-
R
2−NHR−NH
2>R
3−N
Saturated hexacyclic amines is more basic than
aromatic amines.
According to basicity Alkaloids are classified into:
1)Weak bases e.g. :-Caffeine
2)Strong bases e.g.:-Atropine
3)Carboxylic groups e.g.:-Narceine
4)Neutral alkaloids e.g.:-Colchicine
5

6. Chemical
Properties
Stability:-
1)Effect of heat:-Alkaloids are decomposed by heat,
except strychnine and caffeine (sublimable)
2)Reaction with acids:-
Salt formation
Dil acids hydrolyze Ester Alkaloids e.g. Atropine
6

7. CLASSIFICATION
7

8. Pharmacological
Depending upon Physiological response, the alkaloids
are classified under various pharmacological
categories.
Like:-CNS stimulant, or depressant, sympathomimetics,
analgesic, purgatives etc.
Drawbacks:-Of the system is that it does not take into
consideration about chemical nature of crude drug.
Within the same drug the individual alkaloids may
exhibit different action.
Example:-Morphine is narcotics and analgesic while
codeine is mainly antitussive.
8

9. Taxonomic
This method classifies the vast number of alkaloids
based on their distribution in various plant families like
solanaceous alkaloids in Solanaceae family.
The grouping of alkaloids are done as per the name of
genus in which they occur like Ephedra, cinchona etc.
9

10. Biosynthetic
Methods:-gives the significance to the precursor from
which the alkaloids are biosynthesized in the plants.
The variety of alkaloids with different taxonomic
distribution and physiological activities can be brought
under some group if they are derived from same
precursor.
10

11. Chemical
Classification of alkaloids which basically depends on
ring structure present in the alkaloids.
The alkaloids drugs are broadly categorized into two
division.
True alkaloids (subdivided into 12 groups)
Proto alkaloids or biological amines and pseudo
alkaloids.
11

12. True alkaloids
Characteristics:-
1)Sufficient toxicity
2)Wide range of physiological activity
3)Basic nature
4)Presence of nitrogen atom in the hetrocyclic ring
5)Obtained from amino acids
6)Limited taxonomic distribution
7)Occurs in plants in the form of organic acid salt
Exception:-
Colchicine and aristolochic acid are acidic alkaloids
with no nitrogen atom in their heterocyclic ring.
12

13. Classification of
True Alkaloids
Type:-Pyridine and Piperidine
Structures:-
Example:-nicotine, anabasine(tobacco), and lobeline
(lobelia).
13

14. Classification of
True Alkaloids
Types:-Tropane
Structures:-
Examples:-atropine, hyoscine, hyoscyamine
(belladonna, datura), and cocaine (coca)
14

15. Classification of
True Alkaloids
Types:-Quinoline
Structures:-
Examples:-quinine, quinidine, cinchonine, and
cupreine(cinchona).
15

16. Classification of
True Alkaloids
Types:-Isoquinoline
Structures:-
Examples:-morphine, codeine, narcotine, narceine
(opium)emetine, and cephaline (ipecac)
16

17. Classification of
True Alkaloids
Types:-Indole
Structures:-
Examples:-ergotamine, ergometrine (ergot), reserpine
(rauwolfia), vincristine, vinblastine (vinca), strychnine,
and brucine (nux-vomica)
17

18. Classification of
True Alkaloids
Types:-Imidazole
Structures:-
Examples:-pilocarpine and isopilocarpine (pilocarpus)
18

19. Proto alkaloids
The amino acid nitrogens is not situated in the
hetrocyclic ring, hence are characterized as simple
amines.
These alkaloids are synthesized from amino acids and
are basic in nature.
Proto alkaloids are also termed as biological amines
Example:-mescaline, ephedrine etc.
19

20. Classification of
Proto Alkaloids
Types:-Alkylamine
Structures:-
Examples:-ephedrine and pseudoephedrine.
20

21. Pseudo
alkaloids
These basic natured pseudo alkaloids are not derived
from amino acid precursor and are sub-divided into:
i) Steroidal Alkaloids: These alkaloids, e.g., conessine,
have a steroidal moiety.
ii) Purine Bases: These alkaloids, e.g., caffeine, contain a
purine moiety
21

22. Classification of
Pseudo alkaloid
Type:-Purine
Structures:-
Examples:-caffeine, theophylline, and theobromine
22

23. Classification of
Pseudo alkaloid
Type:-Steroidal
Structures:-
Examples:-conessine, protoveratrine
23

24. Classification of
Pseudo alkaloid
Types:-Diterpene
Structures:-C
20H
32
Examples:-aconitine, aconine,and hypoaconine.
24

25. BIOSOURCES
Alkaloids are present in varying quantities, such as:
1) More in dicots than in monocot plants.
2) Lesser common in lower plants.
3) Apocynaceae, Rubiaceae, Solanaceae, and
Papaveraceae families have abundance of alkaloids, while
Rosaceae and Labiatae families are free from alkaloids.
25

26. DISTRIBUTION
IN PLANTS
Sr.
no.
Alkaloids found Plants
01 All plant Datura
02 Barks Cinchona
03 Seeds Nux vomica
04 Roots Aconite
05 Fruits Black pepper
06 Leaves Tobacco
07 Latex Opium
26

27. FORMS OF
ALKALOIDS
Forms of Alkaloids Examples
Free bases
Salts withorganic acids Oxalic ,acetic acids
Salts with inorganic acidsHCl, H
2SO
4
Salts with special acidsMeconic acid in opium
Quinic acid in Chinchona
Glycosidal form Solaninein solanum
27

28. CHEMICAL TEST
28
PRECIPITATION REACTION:
1)Mayer’s or Valser’s reagent
Reagents:-Potassium mercuric iodide solution
Composition:-
Mercuric chloride 1.36
Potassium iodide 5.00 g
Water to make 100 ml
Reaction:-
Test:1ml of extract + 1ml of mayer’s regent Whitish/
yellow or cream coloured precipitate indicates the
presence of alkaloids.

29. CHEMICAL TEST
2)Wagner’s regent
Reagents:-Iodine—potassium iodide
Composition:-
Iodine 1.3g
Potassium iodide 2.0 g
Water to make 100 ml
Reaction:-
Test:1ml of extract + 2ml of Wagner’s reagents
Reddish brown
29

30. CHEMICAL TEST
3)Dragendorff’s or Krauts regent
Reagents:-Potassium iodide + bithmus nitrate
Composition:-
Bismuth nitrate 8.0g
Nitric acid 20.5g
Potassium iodide 27.2g
Water to 100ml
Reaction:-
Test: 1ml of extract + 1ml of Dragendorff’s reagent
Orange-red
30

31. CHEMICAL TEST
4)Hager’s regents
Reagents:-Saturated aqueous solution of picric acid
Reaction:-
Test:1ml of extract + 3ml of Hager’s reagent Yellow
31

32. CHEMICAL TEST
5)Tannic acid solution
Reagents:-Freshly prepared 5% saturated solution of
tannic acid
Composition:-
Tannic acid 5%
Water to 100 ml
Reaction:-
Test: 1ml of extract + 1ml tannic acid reagent Buffer
32

33. CHEMICAL TEST
6)Ammonium reineckate solution
Reagents:-Reineckate Salt Solution
Composition:-
Ammonium Reineckate (NH4 [Cr. (NH3)2 (SCN)4) 1.0gm
Hydroxylamine HCl 0.3gm
Ethanol 100ml
33

34. CHEMICAL TEST
COLOUR REACTION:
1)Van—Urkstest:-(Para-dimethyl-amino-benzaldehyde
+ sulphuric acid)---(for Ergot alkaloids),--gives Blue
colour.
2)Vitali—Morin test:-Test for solanaceous alkaloids
gives violets colour when treated with conc.nitricacid
and alcoholic KOH.
34

35. EXTRACTION
AND ISOLATION
In general, alkaloids may be extracted by any of the
following three well-defined and widely accepted
processes:
1)STAS-OTTO METHOD
2)MANSKE’S METHOD
3)KIPPENBERGER’S PROCESS
35

36. STAS-OTTO
METHOD
36
Technique involves the
distribution of alkaloidal bases
between acid or aqueous solution
and immiscible organic solvent.

37. STAS-OTTO
METHOD
37

38. MANSKE’S
METHOD
38

39. KIPPENBERG’S
PROCESS
39

40. VINCA
Biological Source:-Dried whole plants of Catharanthus
roses
Family:-Apocynaceae
Geographical source:-It is indigenous to Madagascar
and cultivated in south Africa, India, USA, Europe, and
Australia
Macroscopy Character---
1.Color:-Green (leaves)
Pale grey (Roots)
pinkish white or caraminered (flowers)
2.Odour:-Characteristic
3.Taste:-Bitter
40

41. Vinca
4.Leaves:-Simple, peptiolate, ovate or oblong
5.Flower:-Bracteate, pedicellate, complete and
hermaphrodite
6.Fruits:-Follicles with many black seeds.
Chemical constituents:-mainly contain Indole group
with oncocyticaction like vincristine, vinblastine,
ajmacine.
Dose:-Vincristine-10 to 30 mg/body wt: Vinblastine
100 µg/body wt
Microscopy:-
1.Upper surface is single layered rectangular in shape
2.Epidermis consist of unicellular.
41

42. Vinca
3.Covering trichomes
4.Palisade is single layered
5.5-8 layered spongy parenchyma is present
6.Mid rib consist of collenchyma, xylem
7.Phloem present in centre
8.Stomata is of cruciferous
9.Lower epidermis contains calcium oxalate crystals
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43. VINCA
ChemialTest:-Mayer’s, Dragendroff’s, Hager’s,
Wagner’s test
Uses:-
1.Hepatoprotective
2.Anti-allergic
3.Diuretic
4.Anticancer
5.Anti-asthamatic
6.Cardiac activity
7.Imunomodulatoryactivity
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44. VINCA
Cultivation and Collection:-
1)It require dry or moist soil and can tolerate drought.
2)It is cultivated either by directly sowing the seed.
3)Nursery sowing method is found to be economical and
the fresh seed are sown in nursery in the month of
February or march.
4)The seedling attain a height of 5-8 cm after two month
and then they are transplanted into a field at a distance
of 45 cm x 30 cm
5)In order to collect the whole plants, the stem are first
cuts about 10 cm above the ground and leaves, seeds,
stems are separated and dried.
6)The root are collected by plugging which are later
washed and dried under shade and packed.
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45. BELLADONNA
Synonyms:-Belladonna leaf, Deadly night shade
Biological source:-Belladonna herb consist of dried
leafs and other aerial parts of Atropabelladonna
Family:-Solanaceae
Geographical Sources:-Central and south Europe,
England, Germany, America, India(kulu, Kashmir, simla)
Chemical Constituents:-l-Hyoscyamine, Belladonine,
Scopolamine
Dose:-0.6-1 ml Belladonatincture 4 times/day
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46. BELLADONNA
Macroscopy characterstics:-
1.Color:-green to brownish (leaves)
Purple to yellowish (Flowers)
green to brown (Fruits)
2.Odour:-slight and characteristics
3.Taste:-bitter acrid
4.Size:-Leaves(5 to 25 cm long, 2.5 to 12 cm wide)
Flower(corolla 3 cm long 2 cm wide)
Fruits(10 cm diameter)
5.Shapes:-leaves are ovate, lanceolate, acuminate
6.Flowers:-campanulate, small
7.Fruits:-Berries, subglobular
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47. BELLADONNA
Cultivation and collection:-
1)Seed sawn in nursery, then seedling transplanted in
deep well drained, moist, calcareous soil, and loamy
soil in april.
2)Weeding & fertilizing are needed
3)Leaves collected in dry summer weather next 4 ft.
height, flowring15
th
juneto 15
th
july.
4)From 2
nd
cut plants harvesting are done in August and
September and something in October.
5)Root are drug out at 4
th
year
6)Drug dried at 40-60 0C in dark sheds.
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48. BELLADONNA
Microscopy:-
1)Epidermal cells are slightly anticlinical
2)Anisocyticstomata is present, uniserrate, covering
trichomes also present Palisade ration is 5-7
Uses:-
1)Parasympatholytic,
2)Anti-cholinergic
3)Reduce sweat
4)Saliva
5)Gastric juice
6)Spasm
7)Antidote
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