Introduction of Glycosides
Session 27: Introduction of Glycosides
Total Session Time: 60 minutes
Prerequisites
Learning Tasks
By the end of this session students are expected to be able to:
Resources Needed
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |05 Minutes |Presentation |Introduction, Learning Tasks |
|2 |15 Minutes |Presentation |Meaning and Characteristics of |
| | | |Glycosides |
|3 |30 Minutes |Presentation |Classification of Glycosides |
|4 |05 Minutes |Presentation |Key Points |
| 5|05 Minutes |Presentation |Evaluation |
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: Meaning and Characteristics of Glycosides (15 minutes)
|Activity: Brainstorming (5 minutes) |
| |
|Ask students to brainstorm on the following question: |
| |
|What is a glycoside? |
| |
|ALLOW few students to respond |
| |
|WRITE their responses on the flip chart/ board |
| |
|CLARIFY and SUMMARIZE by using the content below |
← Glycosides are molecules in which a sugar part (sugar moiety called the
glycone) is bound to a non-sugar part (non-sugar moiety called the
aglycone) joined together by glycosidic bond
← Glycosides play numerous important roles in living organisms
← Many plants store important chemicals in the form of inactive
glycosides
← Many such plant glycosides are used as medications
← Characteristics of glycosides include;
o Glycosides are soluble in water but insoluble in organic solvents
solvents
solvents
o Glycosides are ccolorless (except flavonoid- yellow, anthraquinone-red
or orange)
o They are solid, amorphous and nonvolatile
o They give a positive reaction with Molisch's and Fehling's solution
test (after hydrolysis).
o Most glycosides have bitter taste
o They are oodorless except saponin (glycyrrhizin).
o Glycosides with lots of sugars have increased solubility in water
o Glycosides hydrolyzed by using mineral acids and temperature or by
using enzymes
STEP 3: Classification of Glycosides (30 minutes)
← Glycosides can be classified base on the following basis:
o Based on therapeutic effects
o Based on glycone moiety
o Based on glycosidic linkage/bond
o Based on chemical nature of the aglycone
STEP 4: Key Points (5 minutes)
← Glycosides are made up of a glycone and aglycone moieties
← Glycosides are water soluble
← Glycosides are hydrolysed by acids, bases and acids into their
components
STEP 5: Evaluation (5 minutes)
← What is a glycoside?
← What are characteristics of glycosides
← What are the classes of glycosides
References:
Gleadow, RM; Møller, BL (2014). "Cyanogenic glycosides: synthesis,
physiology, and phenotypic plasticity". Annual Review of Plant
Biology. 65: 155–85. doi:10.1146/annurev-arplant-050213-
040027. PMID 24579992.
Sun, Hong-Xiang; Xie, Yong; Ye, Yi-Ping (2009). "Advances in saponin-based
adjuvants". Vaccine. 27 (12): 1787–1796. doi:10.1016/j.vaccine.01.091.
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.
Churchill Livingstone/Elsevier.
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