Understanding Medicinal Plants: Their Chemistry and Therapeutic Action
Prof. Bryan Hanson
Instructor's Resource Page for Chapter 7
Key Points
Chapter 7 presents three different case studies about how specific plant drugs work on a molecular level. Each case study involves a different mechanism of action so that students are exposed to varied ways in which drugs act. Each case study is discussed in light of concepts learned earlier but also builds the context needed to understand each particular case. The main point of the chapter as a whole is that the structure of a drug determines how it can bind to its target (Structure Activity Relationships or SAR). This idea was introduced briefly in Chapter 6 in the discussion of targets and receptors, but is pursued in more detail here. The need to compare biological activity in light of three dimensional structure is highlighted.
Learning Objectives
In addition to the objectives listed below for each particular case study, after completing this chapter and seeing concepts from the entire book applied in context, students should be much more independent in their ability to think about how a plant may work. As a non-scientist audience, students are naturally not expected to be self-starters in this area, but with proper background and guidance they should be able to follow the logic and explain some straight-forward data sets. A particular objective of this entire chapter is to convince students that an understanding of the structure of a molecule and a consideration of actual or potential receptors can lead one to understand the true basis for a medicinal plant’s action.
Ayahuasca and The Central Nervous System
After completing this case study, students should:
- Have an appreciation for the traditional cultural context of Ayahuasca
use.
- Understand what is meant by the terms set and setting.
- Be able to describe the major functional categories of the CNS (autonomic,
sympathetic etc).
- Understand and be able to explain the process of nerve impulse travel,
both in the nerve cell and at the synapse.
- Be able to describe some of the targets within the synaptic region where
drugs may act.
- Be able to define the term neurotransmitter.
- Know that the action of Ayahuasca requires two molecules, each with a
specific role, and be able to describe the role of each.
- Continue to develop the ability to study a group of structures and discern the common structural features that might be responsible for their action (SAR).
Ginkgo and Brain Health
Note: in order for students to fully understand this section, they should have read the section on antioxidants in Chapter 5.
After completing this case study, students should:
- Be able to describe the three ways by which the molecules in ginkgo help
to protect the brain.
- Understand the normal role of PAF and how interupting its action can
be beneficial.
- Continue to develop the ability to study a group of structures and discern
the common structural features that might be responsible for their action
(SAR).
- Be able to describe the overall flow of genetic information in a cell and indicate at what points plant drugs might be used to interfere for a useful medicinal effect.
Cancer Treatments from Plants: Interupting the Cell Cycle
After completing this case study, students should:
- Be able to describe the major aspects of the cell cycle and how cells
may become cancerous.
- Be able to describe the structural hierarchy of microtubules, their natural
history and their role in cells.
- Be able to describe different ways in which plant drugs may act on microtubules.
- Describe the process of intercalation and processes in the cell where
it would be important.
- Continue to develop the ability to study a group of structures and discern the common structural features that might be responsible for their action (SAR).
Teaching Ideas, Activities & Resources
In addition to the example cited in the ginkgo case study, another good example of plant extracts affecting expression of brain chemistry can be found in "Proteomic Analysis of Rat Brain Protein Modulations by Grape Seed Extract" Deshane et al Journal of Agricultural and Food Chemistry vol 52 (2004) pgs 7872-7883.
- See the movie recommendations on my Medicinal Plants Bibliography page.
The background on this page is a 19th century woodcut of Phytolacca americana.
Last updated Thursday, September 1, 2011 . Contents & layout copyright 2011 Prof. Bryan Hanson