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High School, Long Island
of Allicin: The
Active Ingredient in Garlic
drugs used by consumers for medicinal purposes are derived from plants.
Plants can be called the first chemists because they can synthesize large
molecules for biological activity. These
compounds are used by plants as defense against plant eating insects and other
are by-products of growth processes
of plants. A number of these plant
compounds have a property or chemical activity useful to humans.
I. Outside Research
Using outside sources, such as the library or
Internet determine the scientific name of garlic and the structural formula for
II. Laboratory Activity
a mortar and pistle, crush a clove of garlic
the crushed garlic and oil in a 50 ml beaker.
the crushed garlic and oil in 20 ml. of ethanol.
the beaker with a watch glass and allow it to stand for half an hour.
15 ml of hexane and 5 ml. of isopropanol in a beaker to produce a 3:1 hexane
the solvent mixture into a TLC chamber. No
more than ¼ of an inch of solvent should be added to the chamber.
a piece of filter paper into a rectangle that fits into the TLC chamber.
a pencil, draw a line approximately 3 cm. from the bottom of the filter paper.
a capillary spotter, place one drop of the garlic/ethanol mixture on the
penciled line of the filter paper.
Place the filter paper in the TLC chamber.
11. Allow it to stand until you see a clear colored band approximately half to three-fourths from the bottom of the paper.
III. Conclusion Questions
chemical causes the strong smelling odor in garlic?
the structural formula of Allicin.
does thin layer chromatography work?
do we use the 3:1 hexane isopropanol as the solvent in the thin layer
What are the other benefits of the ingestion of garlic?
6. What other compounds could you extract from plants? Using the space below, design an experiment to extract a compound of your choice. What kind of solvent would you use in the TLC chamber and why?
York State Standards
The above lesson plan satisfies a number of New York State Learning
Standards for mathematics, science, and technology.
1: Analysis, Inquiry, and Design
Students will use mathematical analysis, scientific inquiry, and
engineering design, as appropriate, to pose questions, seek answers, and develop
2: Information Systems
Students will access, generate, process, and transfer information using
Students will understand and apply scientific concepts, principles, and
theories pertaining to the physical setting and living environment and recognize
historical development of ideas in science.
National Research Council. National Science
Education Standards. National Academy
Press. Washington, DC.
Wilbraham, A.C., Staley, D.D, Matia, M.S., &
Waterman, E.L. Chemistry. Prentice
Hall. Palo Alto, California.
Fifth Edition. 2000.
Zubrick, J.W. The
Organic Chemistry Lab Survival Manual: A
Student Guide To Techniques. Fourth
Edition. Pg. 252-264.