Secondary metabolites- Alkaloids Introduction

Definition, Classification, chemical test, properties , uses, Distribution and occurrence, Extraction isolation, chromatography methods of purification,Function of alkaloids.

1. ALKALOIDS
•Presented by:
•Roma M. Sharma
•Assistant Professor
•GES’s Sir Dr.M.S.Gosavi C.O.P.E.R
•Nashik

2. ALKALOIDS
•CONTENT
Definition
Classification
Functions in plant
characteristics of plant
Distribution and occurrence
Nomenclature

3. Alkaloids
Definition:theterm“alkaloid”(alkali-like)is
commonly usedtodesignatebasic
heterocyclicnitrogenouscompoundsofplant
originthatarephysiologicallyactive.

4. Deviation from Definition:
•Basicity: Some alkaloids are not basic e.g.
Colchicine, Piperine, Quaternary alkaloids.
•Nitrogen: The nitrogen in some alkaloids is
not in a heterocyclic ring e.g. Ephedrine,
Colchicine, Mescaline.
•Plant Origine: Some alkaloids are derived
from Bacteria, Fungi, Insects, Frogs,
Animals.

5. NewDefinition:Alkaloidsarecyclic
organic compounds containing
nitrogeninanegativestateofoxidation
withlimiteddistributionamongliving
organisms.

6. Classification:
•Truealkaloids: (from amino acids and
have nitrogen in a heterocyclic ring. e.g
Atropine
•Protoalkaloidsthat are derived from
amino acids and do not have nitrogen in a
heterocyclic ring. e.g Ephedrine
•Pseudo alkaloidsthat are not derived
from amino acids but have nitrogen in a
heterocyclic ring. e.g Caffeine
•False alkaloidsare non alkaloids give
false positive reaction with alkaloidal
reagents.

7. Function in Plants
•Theymayactasprotectiveagainstinsects
andherbivoresduetotheirbitternessand
toxicity.
•Theyare,incertaincases,thefinalproducts
ofdetoxification(wasteproducts).
•Sourceofnitrogenincaseofnitrogen
deficiency.
•They,sometimes,actasgrowthregulatorsin
certainmetabolicsystems.
•Theymaybeutilizedasasourceofenergyin
caseofdeficiencyincarbondioxide
assimilation.

8. Distribution in Plant:
•All Parts e.g. Datura.
•Barks e.g. Cinchona
•Seeds e.g. Nux vomica
•Roots e.g. Aconite
•Fruits e.g. Black pepper
•Leaves e.g. Tobacco
•Latex e.g. Opium

9. Physical Properties:
I-Condition:
•Mostalkaloids are crystalline solids.
•Few alkaloids are amorphous solids e.g. emetine.
•Some areliquidsthat are either:
Volatilee.g. nicotine and coniine, or
Non-volatilee.g. pilocarpine and
hyoscine.
II-Color:
The majorityof alkaloids are colorlessbut some are
colorede.g.:
•Colchicine and berberine are yellow.
•Canadine is orange.
•The salts of sanguinarine are copper-red.

10. Physical Properties:
III-Solubility:
•Bothalkaloidalbasesandtheirsaltsaresolubleinalcohol.
•Generally,thebasesaresolubleinorganicsolventsand
insolubleinwater
Exceptions:
•Basessolubleinwater:caffeine,ephedrine,codeine,
colchicine,pilocarpineandquaternaryammoniumbases.
•Basesinsolubleorsparinglysolubleincertainorganic
solvents:morphineinether,theobromineandtheophyllinein
benzene.
•Saltsareusuallysolubleinwaterand,insolubleor
sparinglysolubleinorganicsolvents.
Exceptions:
•Saltsinsolubleinwater:quininemonosulphate.
•Saltssolubleinorganicsolvents:lobelineandapoatropine
hydrochloridesaresolubleinchloroform.

11. Chemical Properties:
I-Nitrogen:
•Primary amines R-NH
2 e.g. Norephedrine
•Secondary amines R
2-NH e.g. Ephedrine
•Tertiary amines R
3-N e.g. Atropine
•Quaternary ammonium salts R
4-N e.g d-Tubocurarine
II-Basicity:
•R
2-NH >R-NH
2 >R
3-N
•Saturated hexacyclic amines is more basic than aromatic
amines.

12. •potassium
bismuth iodide
solution
•Observation :
orange
coloured
precipitate
•iodine in
potassium
iodide
•Observation :
red-brown
precipitate
•mercuric
potassium
iodide solution
•Observation:
white
precipitate
•picric acid
•Observation :
yellow
precipitate
HAGERS
REAGEN
T
MAYER
‘S
REAGEN
T
DRAGEN
DORFF'S
REAGEN
T
WAGNER
’S
REAGEN
T

13. Extraction, Purification and Isolation of Alkaloids
from Powdered plants
•Extraction and purification
Method I:
Thepowderistreatedwithalkalistoliberatesthefreebases
thatcanthenbeextractedwithwaterimmiscibleorganic
solvents.
Method II:
Thepowderedmaterialisextractedwithwateroraqueous
alcoholcontainingdiluteacid.Alkaloidsareextractedas
theirsaltstogetherwithaccompanyingsolubleimpurities.
MethodIII:
Thepowderisextractedwithwatersolubleorganicsolvents
suchasMeOHorEtOHwhicharegoodsolventsforboth
saltsandfreebases.

14. Plant material and solvent
Extract
Concentration
Acidified Extract (Alk. as salts)
Organic solvent dissove Impurities
Acidification
Alkalinization
Alkaline aqueous layer
Organic solvent dissove Alkaloids

15. •Chromatographic Methods
•1. Thin layer chromatography (TLC)-
imp tool for qualitative and quantitative analysis of natural
products like alkaloids, glycosides, isoprenoids.
•High performance thin layer chromatography( HPTLC)-
•Tech. applied for compilation of profiles pertaining to varied
range of bioconstituents such as berberine, quinine and
related alkaloids, opium alkaloid, colchicine and also for
detection of adulteration.

16. •Spectrophotometric Methods
1.UV Spectrophotometer
-A Variety of natural product of
pharmaceutical significance are analysed by
spectroscopic method.
e .g
Morphine 286nm,
Lobeline 249nm
Deserpine 268nm

17. •IR ( Infra-Red spectrophotometry)
•It is very evidance that the sample have
the same chemical structure. IR is very
useful tool for detection offunctional group
of biomolecule. E.g alkaloids, quinine
strychnine.

18. •Fluorescence analysis
•Organic molecule absorb the light usually
the specific range of wavelenght and re-
emit such radiation. E.g.
1. belladona leaf fluorescence in visible
range
2. Cinchona bark-no. of luminous yellow
and few light blue pathes.

19. •NMR (Nuclear Magnetic Resonance)
•–Used for the elucidation ofmolecular
structure, specially the stereochemistry
and configuration. and determination of
impurities and minor component.
•Mass Spectrometry-the most imp
application of mass spectrometry is in
determination of molecular weight of
compound.

20. Classification of Alkaloids

21. •Phenylalkylamines:
e.g. Ephedrine
•Pyridine and piperidine
e.g. lobeline, nicotine
•Tropane
e.g. Atropine.CH
2CHCH
3
NH
2 N N
H NCH
3 OH

22. •Quinoline
e.g.quinineandquinidine
•Isoquinoline
e.g.papaverine
•Phenantheren
e.g.MorphineN N

23. •Indole
e.g.ergometrine
•Imidazole
e.g.pilocarpine
•Purine
e.g.caffeineN
H N
N N
N
N
N
H
Purine
1
2
3
4
5
6
7
8
9

24. •Steroidal
e.g.SolanumandVeratrum
alkaloids
•Terpenoid
e.g.Taxol