ER20-13T - PHARMACOGNOSY D.PHARM I YEAR CHAPTER - IV

1. Alkaloids
Presented by
M.Nithya., B.Pharm,
Lecturer, ECOP.

2. CONTENT
• Introduction
• Types
• Occurrence
• Distribution
• Isolation
• Identification test
• Therapeutic activity
• Pharmaceutical application

3. INTRODUCTION
DEFINITION:
• Alkaloids, which mean alkali-like substances, are basic
nitrogenous compounds of plant or animal origin and
generally possessing a marked physiological action on man
or animals, when used in small quantities.
• The nitrogen is usually contained in a heterocyclic ring
system and it mainly derived from amino acids.
• Alkaloids are found in animals, fungi & bacteria.

4. TYPES OF ALKALOIDS
True Alkaloids: Nitrogen founds in the heterocyclic ring and
originates from amino Acids. E.g. Nicotine, Atropine and
Morphine.
Proto – alkaloids: These are also called amino alkaloids; these are
the compounds that lack one or more of the properties of typical
alkaloids.
In proto alkaloids the nitrogen is outside the ring and derived from
amino acids. E.g. Ephedrine , Colchicines,.
Pseudo-Alkaloids: Do not originate from amino acids.
E.g. Caffeine, Theobromine, Theophylline, Steroidal Alkaloids etc.

5. OCCURRENCE
 Rare in lower plants.
 Dicots are more rich in alkaloids then monocots.
 Families rich in alkaloids: Apocynaceae, Rubiaceae,
Solanaceae and Papaveraceae.

6. DISTRIBUTION
All parts: e.g. Datura
Barks: e.g. Chichona
Seeds: e.g. Nuxvomica
Roots: e.g. Aconite
Fruits: e.g. Black pepper
Leaves: e.g. Tobacco
Latex: e.g. Opium

7. ISOLATION OF ALKALOIDS
Stas-Otto Process:

8. IDENTIFICATION TEST FOR ALKALOIDS
EXPERIMENT COMPOSITION OBSERVATION INFERENCE
Mayer’s Test:
To the few ml of
test sample add
Mayer's reagent.
Potassium
mercuric
iodide
solution.
Cream
coloured
precipitate.
Presence of
alkaloids
Dragendorff’s Test
To the few ml of
test sample add
Dragendorff’s
reagent.
Potassium
bismuth
iodide
solution.
Orange red
precipitate.
Presence of
alkaloids

9. Cont…
EXPERIMENT COMPOSITION OBSERVATION INFERENCE
Wagner’s Test:
To the few ml of
test sample add
Wagner's reagent.
Iodine
potassium
iodide
solution.
Reddish brown
coloured
precipitate.
Presence of
alkaloids
Hager’s Test
To the few ml of
test sample add
Dragendorff’s
reagent.
Saturated
solution of
Picric Acid
Yellow colour
precipitate.
Presence of
alkaloids

10. THERAPEUTIC ACTIVITY OF ALKALOIDS
• Alkaloids are Pre-infectional compounds which prevent
bacterial or fungal infections.
• They are used as analgesics or pain relievers.
E.g. Morphine and Codeine.
• Atropine and its synthetic derivatives are used in eye
examinations for eye dialation.
• Quinine is an Antimalarial drug
• Vincristine and Vinblastine are most effective
anticancerous agent.

11. PHARMACEUTICAL APPLICATIONS OF
ALKALOIDS
Alkaloids Application
Morphine Narcotic and analgesic
Codeine Expectorant and analgesic
Quinine Antimalarial
Cocaine CNS Stimulant
Ephedrine Hypertensive
Pilocarpine Miotic
Strychnine CNS Stimulant