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Published Reviews of Understanding Medicinal Plants by Bryan Hanson

Jump to reviews: Economic Botany, Journal of Ethnopharmacology, HerbalGram, Lloydiana, Herbal Therapeutics, Loescher, Quarterly Review of Biology, Community Pharmacy, Phytomedicine.

Review Published In: Economic Botany , Vol. 60, p. 298 (2006)
Reviewed by: Karol Chandler-Ezell, Stephen F. Austin State University

This book makes a unique and welcome contribution to the literature on medicinal botany.  It offers a thorough yet approachable primer to the chemistry of medicinal plants that fills a much-needed middle ground between herbals and more advanced texts on pharmacognosy.  Hanson’s experience as a chemistry teacher at DePauw University in Indiana comes through in his skill at presenting chemical concepts in an approachable, step-by-step way without compromising accuracy.  Hanson’s approach is put forward in the introduction as a balanced appreciation of all that both  medicinal plants and chemistry can offer.  He begins with a statement that will surely find resonance with professionals: “… Many people believe that medicinal plants have some special, mystical properties because they are natural, or organic, or God given.  For similar reasons, some folks reject anything considered a ‘chemical’ because they believe them to be fundamentally bad, or they reject mainstream medicines because they are synthetic… we should not label plants and natural, herbal treatments as superior in all cases.  Like it or not, virtually everything in the world is a chemical or composed of chemicals.”  (pp. 5-6)

Chapter 2 begins an introduction to chemical symbols and how to understand them.  He does a particularly good job of clearly and simply explaining how to understand and “read” chemical structures as they are commonly presented in pharmacognosy and chemical literature.  He then advances in Chapter 3 to basic ways molecules are formed, medicinally important families of chemicals (Chapter 4), and how these common arrangements are important to understanding how compounds work in the body (Chapters 5-6).  Chapter 3 is particularly helpful for the way it demystifies how chemicals interact with each other and why they form different types of arrangements as molecules.  Chapter 4 is probably the section that readers will return to again and again as a reference to understanding commonly encountered families of compounds, and the “family” approach is particularly helpful, as it provides a hierarchy and structure to these chemicals that will be familiar to those acquainted with botany.  Finally, Chapter 7 provides in-depth case studies of Ayahuasca, Ginkgo, and Cancer treatments as a way of demonstrating how the reader can apply their newly-acquired chemical understanding.  The concepts are well-illustrated with tables and figures displaying the chemical structures, bonding, and chemical interactions described.

This book is very well suited to students of ethnobotany, pharmacy, and medicine and would do very well as a text for classes – particularly for students who do not have a background in chemistry.  Readers should be able to use this book not only as a text but also as a valued reference.  I highly recommend it as an addition to the libraries of those who work with economically-important plants.

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Review Published In: Journal of Ethnopharmacology (2006)
Reviewed by:   Michael Heinrich, Centre for Pharmacognosy and Phytotherapy, School of Pharmacy, University of London

Teaching chemistry to anyone interested in medicinal plants has become more and more of a problem.  Students consider many of the classical textbooks as too difficult and, if one puts a chemical line drawing up, students tend to moan and get worried about its alleged complexity.  Therefore, this book comes as a handy addition to our libraries in natural product chemistry and is a very basic and well-presented text on natural products commonly found in medicinal plants.

Sadly the book is misnamed: it is not about understanding medicinal plants (i.e., the numerous aspects of medicinal plant research including pharmacognosy, biology and quality control) nor do their therapeutic actions feature prominently in the book.  Instead, it is specifically about the chemistry of natural products commonly found in these plants and the basic chemistry required to understand such compounds.  The examples are very well chosen and are presented in a very stimulating way.  Six main chapters (and an introduction) form the core of the book:

As the chapter titles suggest, it is a very hands-on approach, certainly useful for advanced college or secondary students or for first year university students.  Great care is taken in explaining the various ways to represent molecules (Lewis projections, space-filling 3D representations and others) and the process of abstraction which is the basis of these representations.  The examples chosen are ones which will certainly interest students (e.g., neuroactive compounds, Ginkgo, and anticancer natural products as part of the last chapter).  The last two chapters are very short and can certainly only provide a very basic introduction.  While the focus is on the chemistry, it brings this topic, which is considered to be too dry by many (not only students) to life and everyone will learn new things from the examples Bryan A. Hanson has chosen.

The book is illustrated with excellent chemical line drawings, numerous detailed graphs showing some experimental set ups and relevant data (e.g., NMR, IR) and some older botanical drawings, which, however, are of varying quality.  For such an introductory book one might have wanted more use of colour graphics and other forms of illustration, but this would have been difficult at this price range.

In sum, while the book certainly does not aim at achieving a comprehensive coverage of the field (as some excellent other ones do, like Dewick, 2002), it provides good introductory information and will hopefully help younger students to overcome their fear of chemistry.  Thus it is of interest for all health related disciplines including, medicine, pharmacy, and of course specifically ethnopharmacology.  In view of this, it is particularly disappointing that the book is (presumably for marketing purposes) misnamed.  This does not do justice to the importance of chemistry in medicinal plant research and use.

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Review Published In: HerbalGram , Vol. 70, p. 72-73 (2006)
Reviewed by: Exra Bejar, Director of Technical Services, Herbalife International Inc.

Are you passionate about learning the basic chemistry and pharmacology of medicinal plants? Were you frustrated by your college professor and then turned off for the rest of your life when dealing with chemistry and biomedical topics? If you say yes to one of these questions, then Understanding Medicinal Plants is the book for you.

This book is an excellent source of information for any college student who has a strong interest in the scientific knowledge required to understand the effects of herbs, as well as for those who are not so attracted to learning chemistry from traditional sources. It is also an exceptional foundation for lay people who want to expand their herbal chemistry and pharmacology knowledge beyond what they find in other magazines and publications.

Having taught physiology and pharmacology in several universities, I have personally witnessed many first-year undergraduate students who took an introductory course in chemistry or biology and then changed their academic goals to non-science. Perhaps these students would have chosen organic chemistry or pharmacology in their career paths if they had found a compassionate mentor, but instead they opted to discard the hard sciences from their curriculum altogether.

For us botanical scientists at heart, who religiously read HerbalGram, we learned chemistry and biology early in life. If we did not like a basic chemistry or biology topic, we would still swallow it as a bad prescription. We thought many of these concepts were absolutely necessary to understand the more complex and fascinating topics such as NMR spectroscopy, secondary metabolism in plants, toxicology, pharmacokinetics, and drug metabolism. If we were bored by the way they were presented, we took a deep breath and thought: “I’m sure this will expand my knowledge and horizons.” We made ourselves believe that the concepts were empowering tools to explore more complex and intricate subjects as we advanced into higher level classes.

However, let’s face it. For the bulk of college students, accustomed to quick visual streams of information and not as interested in science textbooks as many of us, digesting these basic concepts can be a source of frustration. Perhaps we have been taught to believe the hard sciences are just for a privileged group of geeks or those brave enough to pile stacks of information in their brain.

Fortunately, we now have an excellent book and a great teacher who understands college classroom realities in the 21st century and the challenges of teaching biomedical sciences. Dr. Hanson, a professor of chemistry at DePauw University in Greencastle, Indiana, introduces basic chemical and pharmacological concepts clearly and seamlessly, so that students can learn about chemical bonds, secondary metabolism in plants, neuropharmacology, and DNA replication, all from just one source. I have not been in Dr. Hanson’s classroom, but I am pretty sure his students don’t think these topics are boring.

The book includes, among other things, the symbolism of chemical structures, the origins of bonding and molecular properties, and a structural lexicon of medicinally important chemical families found in plants. It reviews the chemical behavior of medicinal molecules (often extracted and purified as drugs), as well their applications. The last two chapters are my favorites—and yes, I am showing a personal bias as a pharmacologist. Dr. Hanson explores the pharmacological action of plant molecules by touching on drug delivery and action, introducing the concept of receptors and molecular targets, as well as providing a clear explanation about levels of action. A very fascinating group of case studies of selected plant drugs is included, which I expect to be particularly appealing to students.

The last section addresses an all-time favorite—the traditional South American ritual concoction ayahuasca and its effects on the central nervous system. It touches on the complex chemistry and effects of B-carboline alkaloids, harmine, harmaline, and tetrahydroharmine, as well as the structural similarity of key ayahuasca molecules with lysergic acid (LSD) and serotonin. It also deals with the complexity of serotonin receptors and how various compounds in this complex plant mixture create the “therapeutic” effect, which is still far from being completely understood.

In an unassuming tone, the book also explains the complex chemistry of ginkgo (Ginkgo biloba, Ginkgoaceae) extract and its antioxidant and pharmacological effects on cerebral circulation, possibly contributing to the medicinal effects. It also describes a number of cancer treatments from plants and natural sources, including an explanation of cell cycle and DNA replication. Thus we learn about the effects of colchicine from autumn crocus (Colchicum autumnale, Liliaceae), paclitaxel from the Pacific yew tree (Taxus brevifolia, Taxaceae), vinca alkaloids from the Madagascar periwinkle (Catharanthus roseus, Apocynaceae), and camptothecin from the Chinese happy tree (Camptotheca acuminata, Nyssaceae).

Any undergraduate student can greatly benefit from this book. Not just the biology, chemistry, and pre-med or pre-pharmacy majors, but also the students studying general education, anthropology, or psychology.  Professional students already enrolled in pharmacy and medicine programs will also find invaluable details on the chemistry and pharmacology of medicinal plants, which can serve as an important source of reference in their careers.

I encourage any university program interested in attracting culturally diverse students to acquire the book. It is a useful reference for learning basic topics in chemistry and physiology, and it would be an asset to any college library that wants to offer more cultural and historical context about the science of medicinal plants.

An example of how the author engages people to learn is demonstrated by the way he describes how ginkgo fossils have been found that are 200 million years old and how this plant was rescued from becoming extinct by Buddhist monasteries in China.  This is followed by a brief discussion of its historical use in China and its more current use as a concentrated and chemically standardized extract in Europe and the United States, where it has been adapted to treat aging conditions and the early stages of Alzheimer’s disease. The historical and cultural references are an excellent way to motivate students to learn more about the chemistry and the pharmacology, which are presented later using a very readable format.

Congratulations to the author in accomplishing a powerful goal—bringing a simple message to students and lay people. Chemistry and pharmacology of medicinal plants really can be interesting and fun to learn!

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Review Published In: Phytomedicine , Vol. 15, No. 4 p. 310 (2008)
Reviewed by: Divya Iyera and Z. Jim Wang, both of the University of Illinois at Chicago.

“Anyone can make the complex complicated, but it takes real genius to simplify the complex.” This adage was the first thing that came to the mind while reading this book written by Bryan Hanson. Through this book, the author skillfully, yet simplistically, puts forth a comprehensive guide to understanding basic chemical and biological principles and applying them to the ultimate purpose of the book – understanding medicinal plants.

The book is broken down into seven chapters. It starts with a brief introduction to the purpose of the book and what a reader can expect to get out of it. A series of questions pertaining to use and science of St. John's wort (Hypericum perforatum L.) immediately catch readers’ eyes at the very beginning of the book. It appears that backgrounds in various areas are required to address these questions, which become the subjects of the book. Immediately followed are four chapters to introduce and prepare readers in several of these areas. Chapter 1 focuses on basic chemistry and structure. Chapter 2 covers rules of chemical bonding, functional groups, chemical nomenclature and molecular formulas. Chapter 3 deals with atoms, electrons and the periodic table. It talks about the formation of ions, the types of chemical bonds formed between atoms and the formation and geometry of molecules. The VSEPR theory and some very clear illustrations of the Newman projections and Sawhorse views of molecules are some of the tools used to explicate these concepts. Chapter 4 is a comprehensive list of the different chemical families such as alkaloids, lipids, etc., with several examples and illustrations of each classification. After the above introduction, the author then illustrates in Chapter 5 how various chemistry tools can be applied in the separation, isolation and structure-elucidation of active components from medicinal plants. A very brief section of bioassays is also included. Principles of pharmacokinetics, including absorption, distribution, metabolism and elimination, are covered in Chapter 6. This chapter also deals with pharmacodynamics by introducing receptors and mechanisms of action at the molecular level. Finally, the author presents several cases of well-known medicinal plants – with an emphasis on the relationship between chemical structures and actions of potential active constituents – including Ayahuasca, a complex mixture used by indigenous Amazonians for spiritual journeys, Gingko biloba, one of the most widely studied plants, and a number of naturally occurring chemotherapeutic agents.

The seamless integration of the tenets of biology and pharmacology with the underlying concept of chemistry is well achieved in the book. The author engages the audience by stories of historical anecdotes, usage and origin. Although the text follows a casual and conversational style, most of materials are well referenced by citations to scientific papers. The plentiful and fitting illustrations of plants (unfortunately not in colors) and chemical structures make the material easier to be comprehended. Each chapter is also followed up with a list of suggested reading, which becomes handy for curious and more advance-level readers who want to delve deeper into a particular area.

The book intends to provide a sound foundation in the understanding of the chemistry and action of medicinal plants, or “what's in them and how they work”, as the author puts it. It largely succeeds in this aspect, while managing to be non-tedious and engaging as well. These traits make it a must-read for budding medicinal chemists. However, this book is also suitable for health profession students, ethnobotanists or even a lay person – anyone seeking to gain some knowledge of the exciting and enigmatic world of natural medicines.

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Review Published In: Lloydiana , Vol. 9, No. 4, p. 8 (Fall 2005)
Reviewed by: Martha Graziano, Chemist, Biologist, and Independent Scholar

This introductory book was written to present information for Hanson’s university level “medicinal plants for poets” class, and anyone who is interested in learning about medicinal plants.  This book presents a general overview of chemical structures, chemical bonding principles, medicinally important classes of chemical actives, a brief survey of isolation and analysis of medicinally active compounds, drug delivery and actions, and case studies of three plant-derived drugs.

The basic chemistry is written in a clear and easy to understand format.  The chemical bonding section lays the groundwork for the rest of the book.

The chapter on medicinally important chemical families provides a brief overview of a vast body of important chemical classes.  Although this is an introductory text, it would be enhanced by a few more examples within these classes.  Some of the sections on the major families, such as terpenes, were a little brief.

In the chapter on chemical behavior and application of medicinal molecules, Hanson surveys various methods of isolating, analyzing, and identifying medicinally active compounds.  The book excels in the practical explanation of chemical procedures that can often be very dry to take in, such as extraction, chromatography, and infrared and mass spectroscopy of  active molecules.  Later in the chapter, the section on antioxidants and reactive oxygen goes into more depth compared to the rest of the book.  This section on antioxidants and metabolism might present a challenge to readers new to chemistry and metabolism.

The chapter on drug discovery and action is a good overview of the absorption, distribution, and metabolism of drugs.  However, the in-depth example of the molecular level of action on succinate dehydrogenase might be a little ambitious for the beginning reader, again compared to the level of the rest of the book.

The case studies of selected plant drugs help bring to life the wonder of medicinal plants and clearly comprise another highpoint of the book.  The case studies on the hallucinogenic South American ayahuasca and gingko are written very well, bringing accessible information around the actions of the plant actives.  Hanson brings the ayahuasca into the discussion after defining its original cultural context before launching into a fascinating discussion of the plant actives and actions.  The case study on ginkgo and brain health is well written and clearly describes the multiple actions of ginkgo in enhancing brain circulation from its antioxidant behavior and its interactions with platelet activating factor, and how ginkgo increases gene regulation of proteins that improve signaling and neurotransmission.  These case studies bring clarity and excitement about plant-derived drugs.

The illustrations of the chemical structures are given in more than one expression, from the stick Lewis structures, ball and stick, and occasionally the space-filling structures for complex macromolecules.  These illustrate the range of relatively simple to rather complex structures of the various active medicinal molecules.  The illustrations of the medicinal plants from classic sources [reproduced with permission from Lloyd Library and Museum resources] are excellent in showing both the beauty and the detail of many of the plants discussed in the text.  They serve as an enjoyable and useful visual to tie in the chemistry and actions of the active molecules to the actual live plants that provide the actives.  The glossary is a robust and useful section.

This book covers an ambitious amount of information from basic chemistry to complex metabolism.  It is a good starting point for those wanting to delve into the chemistry and action of medicinal plants.  The book should leave readers wanting to further explore medicinally active plant medicines.

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Review Published In: Community Pharmacy (www.communitypharmacy.coop/article.cfm?articleID=138)
Reviewed by: Ed Mish, Community Pharmacy book buyer

The author, a chemistry professor at DePaul [sic] University, developed a class for non-science majors called “Medicinal Plants for Poets.” This book, an erudite discussion of how chemicals in plants affect the body, is the natural by-product of that class. Dr. Hanson presents an immense amount of information in an appealing and accessible way. The book contains as much information as a graduate class in biochemistry, yet reads like a witty letter from a buddy who really loves plants.

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Review Published In: Herbal Therapeutics, Inc. on 8-16-05
Reviewed by: David Winston, Herbalist

Few herbalists have in-depth training in Phytochemistry. Is this a significant problem?  The answer is both no and yes.  A good herbalist can practice effectively without knowing the difference between an alkaloid and a flavonoid.  Taste, energetics, differential diagnosis can usually help to discern the appropriate herbs or herbs much more effectively the knowing the plant’s chemistry.  Be that as it may, in today’s increasingly complex world, it is a very good idea for an herbalist to know the difference between aristolochic acid and betulinic acid, between an isoquinoline alkaloid and a  pyrrolizidine alkaloid.  This book explains the chemical and phytochemical mechanisms of medicinal plants to those of us who avoided biochemistry and pharmacology classes in college.  The text is straightforward, with excellent graphics designed to help the chemically challenged grasp this important but daunting area of study.

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Review Published In: Choice: Current Reviews for Academic Libraries (March 2006)
Reviewed by: W. Loescher, Michigan State University

The plant kingdom is a remarkable medicinal resource.  Hanson (chemistry, DePauw Univ.) uses that fact to discuss not only medicinal plants and biological activity, but also organic and biological chemistry.  Although his text is aimed at nonscientists, professionals, pharmacologists, biochemists, and organic chemists may also find much of interest here, and some nonscience students may even rethink their career goals if they use this in a class.  Included are an introduction to chemical structures, with a little information on molecular properties and drug action; somewhat more on chemical behavior relevant to medicinal substances; and also something of a catalog of the  major and minor groups of chemical compounds found in plants.  Hanson explains analytical tools – and how and why they are used – in the context of chemical properties and behavior.  The listings of compounds and plants and their therapeutic properties are quite brief, but this is not an herbal medicine reference work or pharmacopoeia.  It is a quite readable introduction to these medicinal plant materials and their characteristics, particularly in the context of how they act as chemicals in biological systems.  Using a broad-based approach, Hanson subtly and effectively exposes readers to science and how it works. Summing Up:  Recommended.  Lower-level undergraduates through graduate students; practitioners; general readers.

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Review Published In: The Quarterly Review of Biology , Vol. 81, p. 65 (2006)
Reviewed by: N.D. Camper, Clemson  University

This well-written volume is intended for students and other individuals who want to understand how medicinal plants might work in the treatment of a disease or health problem.  It provides chemical, biochemical, and other scientific information that enables readers to understand how the medicinal plant or its constituents might work (i.e., their mode of action).  The text is particularly useful in that it presents chemical and biochemical background information that helps explain how a medicinal plant constituent or extract might act in the body.  The material is particularly appropriate for students as universities and colleges who are non-science majors but have an interest in alternative medicine and medicinal plants.  I would recommend this volume to first-year medical students.

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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