Article pubs.acs.org/jchemeduc
Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX
Plants in Medicine: An Integrated Lab−Lecture Project for Nonscience Majors Annette W. Neuman* and Brenda B. Harmon Department of Chemistry, Oxford College of Emory University, Oxford, Georgia 30054, United States
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S Supporting Information *
ABSTRACT: An integrated lab−lecture project, known as the mini research project, was developed for a medicinal chemistry course for nonscience majors. In the lecture component of this project, students choose a plant essential oil with documented biological activity and prepare a literature review describing the importance, history, and current use of the essential oil as well as identifying the chemical substance responsible for its biological activity. The laboratory component is a four-week experience in which students isolate the essential oil from their chosen plant, analyze its composition by thin-layer chromatography and infrared spectroscopy, and test its antibacterial activity. The objectives of this project are to help students develop the tools to explain structure−function relationships, improve skills in finding sources and evaluating their credibility, and increase student interest and engagement in the lecture and laboratory. Evidence from the final research paper and student surveys indicates that the mini research project was successful in helping students meet these objectives. KEYWORDS: First-Year Undergraduate/General, Curriculum, Laboratory Instruction, Organic Chemistry, Communication/Writing, Inquiry-Based/Discovery Learning, Applications of Chemistry, Medicinal Chemistry, Nonmajor Courses, Plant Chemistry
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students connect chemistry concepts to the real world. Recent papers have described successful theme-based courses focused on food chemistry,6,7 forensics,8,9 perfume chemistry,10 environmental chemistry,11 and drug discovery.12 With our background in medicinal chemistry and the interdisciplinary nature of the topic, this seemed like a natural fit. Some students who take the course are interested in healthcare careers; students who are not interested in healthcare nonetheless find medicinal chemistry to be an applicable and relatable topic. The course is designed to help students answer the question, “How does chemical structure determine function?” Chemistry 120 is structured in three units, as shown in Table 1. Because the course does not have a prerequisite, it begins with an overview of general and organic chemistry topics. The introductory topics are limited to those necessary for a basic understanding of drug discovery and drug action. While medicinal chemistry topics are studied in depth at the
ngaging nonscience majors in the chemistry classroom and laboratory can be a challenge. For example, nonchemistry majors often have negative attitudes toward chemistry, and many students associate the study of science with the memorization of facts and concepts rather than the authentic practice of science.1,2 Guided-inquiry instruction methods have been reported to enhance student engagement in science courses, but a majority of these studies have focused on courses for science majors.3,4 Encouraging students to make connections between science course material and their lives promotes both interest and performance for all students.5 Oxford College, one of the nine academic divisions of Emory University, is a liberal arts college for first- and secondyear students. Science classes are limited to 24 students, and faculty teach both lecture and laboratory. Oxford’s focus on inquiry-guided learning made the development of an integrated lab−lecture project an appealing objective in the improvement of the course. Chemistry 120 at Oxford College is a one-semester survey of chemistry. It has evolved from a survey of organic and biochemistry serving Emory’s nursing school to a general education course. During this transition, we noticed that students’ background in chemistry decreased; their interest in the subject matter also declined as we began to serve a broader group of students. The current student population in Chemistry 120 includes a mixture of prospective science and nonscience majors as well as prenursing, premedical, and prebusiness students. In an effort to enhance student interest and performance in the course, we decided to develop a theme-based approach that would help students connect chemistry to their lives. Theme-based courses are a popular approach for nonmajor courses as they facilitate student engagement while helping © XXXX American Chemical Society and Division of Chemical Education, Inc.
Table 1. Overview of Topics in Chemistry 120 Unit 1 2 3
Title Structures of atoms and molecules Tools for studying chemistry Medicinal chemistry
Sample Topics Bonding, Lewis structures, molecular geometry, electronegativity, polarity, structures of organic compounds, isomers Thermodynamics, types of chemical reactions, attractive forces, acids and bases Drug discovery and development, amino acids and proteins, enzymes, receptors, pharmacokinetics, intellectual property
Received: July 20, 2018 Revised: November 13, 2018
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DOI: 10.1021/acs.jchemed.8b00583 J. Chem. Educ. XXXX, XXX, XXX−XXX
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end of the semester, drug molecules are woven into the entire semester to illustrate various concepts. For example, the chemical structure of emtricitabine (an HIV drug invented by scientists at Emory University) is examined on the first day of class as an example of how chemists represent molecular structure. We utilize a variety of activities and assessments to encourage students to think about chemistry in different ways, including weekly problem sets, case studies, a mini research project, and a capstone literature research project. Syllabi for the lecture and laboratory components of the course can be found in the Supporting Information. In this paper, we describe the mini research project, which provides a foundation for the skills students will hone as they complete their final project.
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DEVELOPMENT OF THE MINI RESEARCH PROJECT For several years, Chemistry 120 had concluded with a capstone literature research project in which students were tasked with providing a literature-based explanation of how a particular topic in organic chemistry affects personal or public health. Students were given the freedom to choose their own topic and wrote about subjects such as the neurotransmitter dopamine and the breast cancer drug tamoxifen. After reading these papers, we noticed that many students were writing a few paragraphs about the structural features of their chosen molecule and then a separate section about its relevance to health. Many students were not addressing the connection between chemical structure and biological function that was at the heart of the course. To address this deficiency, we clarified the assignment for the final project: students in recent semesters have been asked to complete a literature-based paper about an FDA-approved medicine of their choice addressing the question, “How does the chemical structure of this drug determine its biological function?” The full assignment details can be found in the Supporting Information. At the same time, we noticed that students had difficulty finding sources, evaluating their credibility, and properly citing them. An analysis of final papers from Spring 2015 (n = 12) revealed that students relied heavily on Internet and media sources of varying reliability (Figure 1). Even though the assignment information stated that students were required to cite at least one scholarly work (this was defined as a book or journal article), only half the class met this criterion. Students were not convinced of the value of journal articles and did not know how to find or use them. Furthermore, 16% of students did not cite any sources in their final papers. These observations illuminated the need for an introduction to the research process before students embarked on their final paper. To address the challenges above as well as our desire to increase student engagement in the course, we developed the mini research project. In this project, a literature review is integrated with a laboratory project in order to help students connect the concepts of medicinal chemistry with experimental techniques of separation and identification.
Figure 1. Students cited, on average, 6.9 sources in their final papers. Internet and media sources were classified as “high-quality” or “lowquality” according to their currency, reliability, authority, and point of view. Media sources more than 10 years old and peer-reviewed articles more than 20 years old were classified separately.
semester. This integrated lab−lecture project involves students in the authentic practice of science and gives them an opportunity to practice their skills in writing a literature review and a lab report. In this project, students choose a plant with medicinal activity and research its historical use in folk medicine. They submit a literature review of the subject and also isolate and analyze the essential oil from their plant of choice in the lab. Students are introduced to this project in the first week of lab with a discussion of how illness and injury were treated before the development of modern medicine. Herbal remedies were an important component of early medicine and have been used by humans since prehistoric times.13 Herbal remedies remain popular in modern times; even among modern drugs, around a quarter are derived from plants.14 In many cases, the medicinal compounds are contained in the plant’s essential oil. This introduction also includes a discussion about valid sources. Students are introduced to the CRAP test, a tool for evaluating the credibility of a source according to its currency, reliability, authority, and point of view.15 The handout used for evaluating sources can be found in the Supporting Information. For this project, students are tasked with choosing a medicinal essential oil to study. In the fourth week of the semester, they submit a mini research paper; in the lab, they subsequently isolate and analyze the essential oil. The goals of this project are to help students develop the tools to explain structure−function relationships, improve skills in finding sources and evaluating their credibility, and increase student interest and engagement in the lecture and laboratory. The mini research paper is a two- to three-page paper in which students provide a literature-based description of their chosen medicinal plant. Students address the importance, history, and current use of the essential oil and identify the chemical substance responsible for its biological activity. At this point in the semester, we have studied chemical bonding and representations of chemical structures, but students are not yet equipped to understand how chemical structure determines biological activity. Students are required to use valid sources: peer-reviewed journal articles and/or media reports that pass the CRAP test. Further training on finding
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THE MINI RESEARCH PROJECT In a study of student interest in science, Yang recommended that science educators design assignments that engage students in scientific inquiry projects led by their own interests.2 With this in mind, we designed a “mini research” project that Chemistry 120 students complete in the first half of the B
DOI: 10.1021/acs.jchemed.8b00583 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Table 2. Chemistry 120 Laboratory Schedule Week
Title
1 2
Introduction Thin-Layer Chromatography (TLC) Isolation of Caffeine from Tea Isolation of Clove Oil from Cloves Isolation of Essential Oils from Plants Biological Testing Infrared (IR) Spectroscopy Writing Workshop Isolation of Carvone Polarimetry Combinatorial Synthesis of Antibiotics Biological Testing of Antibiotics
3 4 5 6 7 8 9 10 11 12 a
b
Details
c
Introduction to the chemistry lab; introduction to herbal medicine; evaluating the credibility of sources TLC analysis of analgesics Liquid−liquid extraction and TLC analysis of caffeine Steam distillation, liquid−liquid extraction, and TLC analysis of clove oila Steam distillation and liquid−liquid extraction of the essential oil from the student’s medicinal plant of choice;a TLC analysis of essential oil Kirby−Bauer disk-diffusion assay of essential oil activity against Bacillus cereusb,c Inquiry-based introduction to IR spectroscopy;d analysis of essential oil Peer evaluation of lab reports according to a rubric provided by the instructor Steam distillation, liquid−liquid extraction, and TLC analysis of the two stereoisomers of carvonea Polarimetric analysis of the two stereoisomers of carvone Synthesis of a small library of hydrazonese Kirby−Bauer disk-diffusion assay of hydrazone activity against Escherichia colie d
See ref 19. See ref 20. See ref 21. See ref 22. eSee ref 23.
worked with. We provide a generic procedure and allow the students to work in pairs to carry out the experiments using their chosen plants. The generic procedure is provided in the Supporting Information. Students have selected plants such as eucalyptus, lavender, rosemary, and peppermint. Students typically obtain 3−10% recovery, depending on the type of plant used and the quality of their technique. This provides sufficient essential oil for the subsequent analyses. When students have difficulty with the isolation, we provide them with a sample of bottled essential oil for the analyses. The success of this project at meeting learning objectives was assessed via student performance on the final paper and responses to pre- and postproject surveys (Table 3). While
and reading peer-reviewed journal articles comes through a library session later in the semester, so students are not required to use them for this assignment. The full assignment details can be found in the Supporting Information. The laboratory component of the mini research project is inspired by experiments that offer “research-like” experiences for students.12 In considering how to incorporate components of research into a nonmajors course, we knew that such an experience would require a higher level of structure than research projects in more advanced courses. Furthermore, the laboratory environment is crucial to a successful research-like experience. We are careful to project a culture of curiosity in which unexpected results are approached with openness rather than criticism. This helps students to be relaxed in the lab rather than worry that their experiments will not yield acceptable data. An important feature of Chemistry 120 Lab is the focus on building a small number of skills, rather than providing a broad overview of many experimental techniques. Therefore, the laboratory component of the mini research project is situated in the middle of the semester, in weeks five through eight (Table 2). This gives students an opportunity to develop their skills and confidence in the lab before embarking on the research-like experience. Several experiments with essential oils have been reported;16−18 we use a procedure adapted from O’Shea et al.19 Students work in pairs to first isolate the essential oil from the leaves of their plant and subsequently analyze the chemical composition and biological activity of the isolated oil. Students are given information about how to carry out each experiment: more detailed procedures for new techniques and reminders for previously introduced methods. Because students are given the freedom to choose their own topics, each group’s separation and analysis process is different. Detailed instructor notes are available in the Supporting Information.
Table 3. Student Achievement of Mini Research Project Learning Objectives Assessment Mechanism
Student Achievementa
1. Develop the tools to explain structure−function relationships 2. Effectively find sources and evaluate their credibility
Final paper
32% mastery, 23% above average, 18% satisfactory
Final paper
3. Increase student interest and engagement in the lecture and laboratory
Surveys
Students used an average of 4.3 peer-reviewed sources. Survey responses indicated a high level of student engagement.
Learning Objective
a
Based on 22 students.
students were not expected to analyze structure−function relationships in the mini research paper, we hoped that this introduction to research would lead to higher-quality final papers when students analyzed the structure−function relationships of prescription drugs. The mastery of structure−function relationships in the final paper was evaluated according to the rubric in Figure 2. When evaluating the final papers using these criteria, 32% of students displayed mastery in describing structure−function relationships. Among papers that were above average and satisfactory in their analysis of structure−function relationships, many students identified the biological target and structural features of the drug molecules but neglected to explain how those features allowed the compound to interact with its biological target. Six of 22 papers (27%) were
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RESULTS In this project, students are given the freedom to choose an essential oil to study. The only restrictions are that the essential oil must have documented medicinal uses (even if only a folk remedy), and it must come from a readily available plant. As a result, each time we conduct the mini research project, we are faced with plant choices that we have never C
DOI: 10.1021/acs.jchemed.8b00583 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 2. Rubric for the evaluation of students’ use and explanation of structure−function relationships for their chosen drug in the final research paper.
20 responded to the postproject survey. The greatest gains were in the students’ confidence in “Clearly and concisely expressing my findings in a research paper”: in the preproject survey, only 38% of respondents agreed with this statement; in the postproject survey, 85% of respondents agreed. Students also increased their confidence in evaluating the credibility of sources: in the preproject survey, 63% reported that they could do this; in the postproject survey, 85% reported that they could. The postproject survey asked students about their attitudes toward the project itself, as shown in Figure 4. The majority of respondents (80%) felt that the project helped them see the relevance of chemistry in the real world. Most (85%) reported that they understood how scientists use TLC, IR, and biological assays to understand the properties of matter. Most (75%) felt that the project should be continued. The surveys also included open-ended questions in which students were asked to share their perceptions of the mini research project. Several themes emerged from a qualitative analysis of student responses; samples of supporting quotes are provided below. (1) The in-depth knowledge of a plant and essential oil gained from the literature review allowed students to approach the laboratory work in a way that made it more relevant, engaging, and exciting. • The project was awesome. It was so cool to see it play out over the weeks and bring to life something we researched and read about. • I liked how lecture related to lab. It’s nice to really understand something before having to work with it in a lab setting. • I liked being able to research a plant of my choosing and then extracting the essential oils f rom the plant. It was a great way to validate my research and actually handle the materials I discussed in my paper. (2) Students were highly motivated by being able to select their own medicinal plant. • The ability to choose which plant we worked with made the experiment much more engaging. • I enjoyed choosing and researching a plant, then being able to work with the plant in lab. I liked the freedom to choose the plant. • I enjoyed being able to pick my own essential oil rather than conduct an experiment on a random one that I didn’t care much about. (3) The laboratory was designed in a way that emphasized depth of skill over breadth, allowing students to slowly
evaluated as unsatisfactory in this objective; these students identified the biological target but did not identify structural features of the drug molecules. We recognize that such a detailed analysis was not possible for all topics as the specific mechanism of action is not known for all drugs; this likely contributed to the lower scores that some papers were assigned for this objective. Excerpts from student papers can be found in the Supporting Information. Students who had completed the mini research project showed surprising levels of comfort with the scientific literature (Figure 3). Despite only being required to cite one peer-
Figure 3. Students cited, on average, 10.6 sources in their final papers. Internet and media sources were classified as “high-quality” or “lowquality” according to their currency, reliability, authority, and point of view. Media sources more than 10 years old and peer-reviewed articles more than 20 years old were classified separately. One patent and one documentary were cited; these were classified as “other”.
reviewed article in their final papers, these students (n = 22) used an average of 4.3 peer-reviewed articles, comprising more than 40% of their total sources. While many of them did use media sources that were classified according to the CRAP test as low-quality, such sources made up a relatively small portion of their total citations. Furthermore, students reported in a postproject survey that they realized the importance of citing credible and reliable sources. We used pre- and postproject surveys to evaluate student interest and engagement in the lecture and laboratory for the mini research project. These surveys contained statements on attitudes toward studying science and chemistry in particular; responses were gathered with a five-point Likert scale ranging from 1 = “strongly disagree” to 5 = “strongly agree.” There were 24 students who responded to the preproject survey, and D
DOI: 10.1021/acs.jchemed.8b00583 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 4. Student response frequencies for evaluation of the mini research project.
The Kirby−Bauer disk-diffusion assay, while a simple method, has several steps that may lead to aberrant results. This can be challenging in a chemistry lab because the students and instructor may have limited familiarity with the method. We have found it most helpful to have a student assistant who is proficient in the disk-diffusion assay protocol (typically from their biology laboratory courses) and to check the plates after 2 or 3 days to ensure bacterial growth. The most common problems we have encountered are inadequate inoculation, contamination of the disks, and bacterial species that are not susceptible to the substances being tested. More information about the assay is available in the Supporting Information.
develop confidence with the skills necessary for isolating and identifying components of the essential oils. The student level of confidence in their laboratory abilities increased their enjoyment of the entire project. • I enjoyed combining all of the lab skills I have learned this semester into one interesting experiment. It solidif ied my understanding of the lab techniques in a f un and engaging way. • I felt comfortable with the procedures. This experiment was a great way to synthesize all of the skills we had learned so far in lab! • The most interesting new concept that I have mastered as a result of taking this class are lab skills. I f ind it fascinating that I now know how to do extractions, steam-distillations, TLC, and bacterial assays.
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AVENUES FOR MODIFICATION This project could be modified for use in a standard general, organic, and biochemistry (GOB) course; a first-year seminar; a second-year organic chemistry course; or a biology course. In a higher-level chemistry course, students could separate the components of the essential oil by chromatography and carry out a more extensive characterization using nuclear magnetic resonance (NMR) spectroscopy. The disk-diffusion assay has been carried out successfully with nonmajors and second-year organic chemistry students; it requires little background in biology and is rewarding for students to observe the activity of substances they isolated.
(4) Students valued the writing experience.
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• I think my scientific writing has improved significantly because of this course. • I really liked the research paper because it was dif ferent than a normal chem class.
CHALLENGES Allowing students to choose their own topic is integral to the level of engagement observed in this project. At the same time, this approach can lead to increased chaos in the lab as it is likely that some students will choose plants that the instructor has not worked with. We have found a go-with-the-flow attitude to be helpful in the lab; since we have not isolated the essential oils from all of the students’ chosen plants, we do not require a particular threshold of yield. In a multiweek lab project, it is important to have a back-up plan so that groups who do not successfully isolate enough essential oil from their plant can still complete the subsequent experiments. We have purchased small bottles of each chosen essential oil, which are used for comparison in the TLC experiment and also serve as a safety net for students to analyze in the event that they do not isolate sufficient essential oil.
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CONCLUSION
The mini research project provides a way to introduce students to the field of medicinal chemistry by studying a medicinal plant through a literature review and a series of laboratory experiments. Students develop skills in explaining structure− function relationships and learn how to effectively find sources and evaluate their credibility, and they are engaged and excited about the practice of science. In addition, feedback from students was very positive through written evaluations. Greater intentionality in course design, through the mini research project as well as the library session and revision of the E
DOI: 10.1021/acs.jchemed.8b00583 J. Chem. Educ. XXXX, XXX, XXX−XXX
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assignment for the final paper, resulted in students achieving the desired learning objectives.
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(15) CCCOnline Library. Learn about Evaluating Sources: CRAP Test. http://ccconline.libguides.com/c.php?g=242130&p=2185475 (Accessed October 26, 2018). (16) Ciaccio, J. A.; Alam, R.; D’Agrosa, C. D.; Deal, A. E.; Marcelin, D. Isolation and Identification of Nepetalactone Diastereomers from Commercial Samples of Nepeta cataria L. (Catnip): An Introductory Organic Laboratory Experiment. J. Chem. Educ. 2013, 90 (5), 646− 650. (17) Barcena, H.; Chen, P. An Anesthetic Drug Demonstration and an Introductory Antioxidant Activity Experiment with “Eugene, the Sleepy Fish. J. Chem. Educ. 2016, 93 (1), 202−205. (18) Just, J.; Bunton, G. L.; Deans, B. J.; Murray, N. L.; Bissember, A. C.; Smith, J. A. Extraction of Eugenol from Cloves Using an Unmodified Household Espresso Machine: An Alternative to Traditional Steam-Distillation. J. Chem. Educ. 2016, 93 (1), 213−216. (19) O’Shea, S. K.; Von Riesen, D. D.; Rossi, L. L. Isolation and Analysis of Essential Oils from Spices. J. Chem. Educ. 2012, 89 (5), 665−668. (20) Bauer, A. W.; Kirby, W. M. M.; Sherris, J. C.; Turck, M. Antibiotic Susceptibility Testing by a Standardized Single Disk Method. Am. J. Clin. Pathol. 1966, 45 (4), 493−496. (21) Miles, W. H.; Smiley, P. M. Modeling the Drug Discovery Process: The Isolation and Testing of Eugenol from Clove Oil. J. Chem. Educ. 2002, 79 (1), 90. (22) Bennett, J.; Forster, T. IR Cards: Inquiry-Based Introduction to Infrared Spectroscopy. J. Chem. Educ. 2010, 87 (1), 73−77. (23) Wolkenberg, S. E.; Su, A. I. Combinatorial Synthesis and Discovery of an Antibiotic Compound: An Experiment Suitable for High School and Undergraduate Laboratories. J. Chem. Educ. 2001, 78 (6), 784−785.
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.8b00583. Course and laboratory syllabi, course and laboratory handouts, instructor notes, and excerpts from student papers (PDF, DOCX)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Annette W. Neuman: 0000-0002-1170-1107 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We are grateful to the Emory University Center for Faculty Development and Excellence, which supported this work through a Fund for Innovative Teaching grant. We also thank our lab assistants, Augustine Kang and Karine Kasti, who helped us design and carry out the laboratory component of the mini research project.
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REFERENCES
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