In the Laboratory edited by
Second-Year and AP Chemistry
John Fischer Ashwaubenon High School Green Bay, WI 54303-5093
Modeling the Drug Discovery Process: The Isolation and Biological Testing of Eugenol from Clove Oil
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William H. Miles* Department of Chemistry, Lafayette College, Easton, PA 18042;
[email protected] Patricia M. Smiley* Southern Lehigh High School, Center Valley, PA 18034;
[email protected] Chemistry plays a vital role in the discovery and development of pharmaceuticals (1). One important source of new drugs for the pharmaceutical industry is from nature (2). Although college students in organic chemistry often isolate chemicals from natural sources such as cloves, orange peels, and cinnamon (3), these types of experiments are also appropriate for second-year or advanced placement chemistry students in a high school setting (4a). If the isolation of a natural product is also coupled with biological testing (4), then the students can “discover” a biologically active compound. These experiments expose students to the fact that chemistry and biology are commonly integrated in a research environment and allows them to apply chemical concepts to a practical problem. Clove oil, the essential oil isolated by steam distillation of cloves, is an excellent starting point. It has significant antiseptic activity owing to the presence of eugenol, which is easily separated and purified using a chemically active extraction procedure. We have found that the antibiotic behavior of clove oil is readily assayed using Bacillus cereus. Cultures were prepared with simple techniques and the bioassay was completed within one day. When the students tested eugenol and the neutral compounds (eugenol acetate and β-caryophyllene) from clove oil using B. cereus, they discovered that the active compound in clove oil is eugenol (Fig. 1). This experiment illustrates the principles of modern drug discovery for second-year and advanced placement high school chemistry students. We ran this experiment with AP chemistry students after the AP exam when the demand for specific experiments was reduced. An interdisciplinary experiment appealed to students with varied interests and, in particular, to potential science majors. The class responded enthusiastically to this experiment and was highly satisfied with isolating and identifying a biologically active compound. Hazards This experiment should be conducted in a well-ventilated room with eye and hand protection. Clove oil and its constituents are irritants. Hexane is highly flammable. Aqueous solutions of sodium hydroxide and hydrochloric acid are caustic and corrosive and will cause serious burns. Acknowledgments We would like to thank the following AP chemistry students at Southern Lehigh High School for their helpful 90
Figure 1. Test disks (clockwise from top) of a control, clove oil, neutral compounds from clove oil, and eugenol from clove oil against Bacillus cereus on a nutrient agar plate. Inhibition of bacterial growth is seen as a clear halo around the disk.
comments and their enthusiasm for trying this procedure: Scott Breloff, Stefan de Biasi, Dennis Farley, Mark Fuggiti, Sarah Robertson, Ryan Stellar, Travis Thatcher, Agata Bielska, Alix Edwards, Alec Fenstermaker, Chris Halleman, Steve Ilyes, Chris Kubek, Audrey Moore, Eric Pukszyn, Dave Stein, Jason Strobl, and Andy Walker. W
Supplemental Material
Background information, experimental procedures, notes for the instructor, photographs, and a lab report form are available in this issue of JCE Online. Literature Cited 1. Breslow, R. J. Chem. Educ. 1998, 75, 705–717. 2. Agosta, W. C. J. Chem. Educ. 1997, 74, 857–860. 3. Ntamila, M. S.; Hassanali, A. J. Chem. Educ. 1976, 53, 263. Palleros, D. R. Experimental Organic Chemistry; Wiley: New York, 2000. 4. For some examples of chemistry experiments incorporating bioassays, see (a) Krantz, A.; Jesaitis, R. G. J. Chem. Educ. 1973, 50, 76–78. (b) Thadeo, P. F.; Mowery, D. F. J. Chem. Educ. 1984, 61, 742. (c) Beatty, J. H. J. Chem. Educ. 1986, 63, 768–769. (d) Russo, R. N.; Parrish, S. J. Chem. Educ. 1995, 72, 49–50. (e) Lieberman, M. J. Chem. Educ. 1999, 76, 1689–1691.
Journal of Chemical Education • Vol. 79 No. 1 January 2002 • JChemEd.chem.wisc.edu
