NTA Level 5 • Semester 2 • PST05210

Proto alkaloids

Basic Pharmacognosy • Source Session/Topic 26

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Session 26: Proto alkaloids

Total Session Time: 60 minutes

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define proto-alkaloids

• Explain natural source and uses of proto-alkaloids

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

• LCD Projector and Laptop

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing.

STEP 2: Introduction to Proto-alkaloids (10 minutes)

|Activity: Brainstorming (3 minutes) |

| |

|Ask students to brainstorm on the following question: |

| |

|What are the characteristics of proto-alkaloids? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARIZE by using the content below |

• Proto-alkaloids do not have nitrogen as part of the heterocyclic ring

• Proto-alkaloids include ephedrine adrenaline,

• Both cause dilation of the bronchi, increase heart rate and peripheral

vasoconstriction

STEP 3: Natural Sources of Proto-alkaloids (35 minutes)

• Ephedra

o Ephedra is a protoalkaloid obtained from dried young stems of Ephedra

gerardiana and Ephedra nebrodensis, family Ephedraceeae

o Its synonym is Ma-Huang

o Constituents

▪ Ephedrine

▪ Nor-ephedrine

▪ Pseudoephidrine

▪ N-methylephedrine

o Uses

▪ Included in asthma, colds, flu and Hayfever medications

• It is a bronchodilator

• Action is more prolonged than adrenaline

• Need not be given by injection, but can be administered orally

• Allopathic: Sinumed (dries a runny nose)

• Used as an anti-inflammatory.

• Used for weight loss

• Increases metabolism

• Decreases appetite

• CNS stimulant – acts on adrenergic receptors

• Colchicum

o Colchicum is the dried ripe seeds of Colchicum luteum and Colchicum

autumnale.

o Family: Liliaceae

o Constituents

▪ Colchicine (main constituent)

▪ Demecolcine

o Uses

▪ Relieves gout (used with caution – professional supervision)

▪ Also used in biological experiments to produce polyploidy

(multiplication of the chromosomes in a cell nucleus) in

horticulture and cultivation of medicinal plants

STEP 4: Key Points (5 minutes)

• Proto-alkaloids do not have nitrogen as part of the heterocyclic ring

• Ephedra is a protoalkaloid obtained from dried young stems of Ephedra

gerardiana and Ephedra nebrodensis

• Ephedrine is a bronchodilator which is included in asthma, colds, flu and

hay fever medications

STEP 5: Evaluation (5 minutes)

• What is the natural source of Ephedra?

• What are the uses of ephedrine?

References

Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans

pharmacognosy. London: Saunders.

Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical

Press

Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS.

Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996).

Pharmacognosy and pharmacobiotechnology. Baltimore: Williams &

Wilkins.

Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J.

D. (2012). Fundamentals of pharmacognosy and phytotherapy. Edinburgh:

Churchill Livingstone/Elsevier.

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