Understanding Medicinal Plants: Their Chemistry and Therapeutic Action
Prof. Bryan Hanson
Instructor's Resource Page for Chapter 6
Chapter 6 teaches students how to think on a molecular level about how drugs work, building upon the concepts in earlier chapters. First the general issues of adsorption, distribution, metabolism and excretion (ADME to the medicinal chemist) are covered, relying heavily on students’ understanding of how structure affects polarity (developed in Chapters 3 & 5). Then, the issues of how drugs bind to their targets are developed using some basic notions about complementary shapes and intermolecular attractions. This material is essential to understanding the case studies in Chapter 7.Learning Objectives
- Be able to define the terms pH, metabolism, equilibrium, enzymes, isozymes, target, receptors, ligand, substrate, hydrogen bonding, electrostatic interactions, hydrophobic attractions, chirality, and enantiomers.
- Understand that drugs given by different routes encounter different metabolizing enzymes and pH conditions, which in turn affect their action.
- Be able to explain the concept of a chemical equilibrium as it applies to the binding of drugs to circulating blood proteins, and how this affects the dosing of the drug. Also, extend this model to the interactions that result when both strong and weak binding drugs are present.
- Understand how drug structure and polarity affect transport across membranes, and realize that membranes in various organs may differ (the structure of membranes is covered in Chapter 5 in the section on antioxidants).
- Understand how the pH of various body fluids interacts with the functional
groups present in a drug molecule to increase or decrease polarity and
- Be able to state the general goal of metabolizing foreign substances
(drugs), and give examples of how this is accomplished in Phase I and II
- Be able to describe how inducible enzymes and isozymes affect the metabolism
- Be able to describe what is meant by a drug target, and give several
- Describe the two main means by which a receptor or enzyme recognizes
its ligand or substrate.
- List the three main types of attractive forces by which functional groups
may interact as part of a binding event.
- Decide, using the natural substrate as a reference point, which molecules
in a list might also bind to a given target.
- Understand the concept of chirality and explain why it is relevant to drug action. Be able to recognize a chiral center.
Teaching Ideas, Activities & Resources
- Prof. David Flockhart at IUPUI maintains a list of Cytochrome P450 isozymes that metabolise, induce and inhibit common drugs. This is a very useful resource for illustrating drug interactions. It includes a few examples of medicinal plants.
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