T he Yellow Emperor?s Internal Classics, an 18-volume medical reference work, was published some 2000 years ago in China. Written by several generations of traditional Chinese medicine (TCM) practitioners, it describes--with remarkable accuracy--the human body in terms of its anatomy, physiology, and psychology.

The book also focuses a great deal of attention on the medicinal uses of plants--particularly herbs. Together with The Yellow Emperor?s Internal Classics, contemporary books such as The Poetry Classics and The Mountain and Sea Classics identified close to 200 therapeutic plants, including herbs with tonic, contraceptive, antidotal, and antiparasitic effects. There are now over 9000 reports of TCM medicines; however, only about 500 of these are commonly used by TCM practitioners, and only 80 or so (see the box for some examples) have amply demonstrated pharmacological effects--from the perspective of ?modern? medicine.

Herbs That Work

Name of the herb

Ailments it treats

Rhizoma Coptidis (coptis root)

Bacterial infection of alimentary canal

Radix et Rhizoma Rhei (rhubarb root)

Constipation, hepatic jaundice

Herba Ephedrae (Ma Huang Herb)

Hypotension, asthma

Radix Puerariae (Pueraria root)

Ischemic heart diseases such as angina pectoris

Bupleuri (bupleurum)

Common cold

Radix Sophorae Flavescentis

(flavescent sophora root)

Ventricular arrhythmia

Folium Isatidis (isatin leaf)

Respiratory infection

Radix Notoginseng (notoginseng root)

Hemorrhagic peptic ulcer and hemoptysis

Rhizoma Ligustici Chuanxiong

(Chinese lovage root)

Thrombosis

Radix Salviae miltiorrhizae (salvia root)

Coronary heart disease and oxidative stress

Folium Ginkgo (ginkgo leaf)

Coronary and cerebrovascular disease

Radix Ginseng (ginseng root)

Hemorrhagic and infectious shock

Radix Astragalis (astragalus root)

Immunologic inadequacy

These pharmacological effects typically mirror those originally described for the herbs by the Chinese physicians of 2000 years ago, although modern studies have in some cases revealed new pharmacological benefits that were not previously recognized by TCM doctors.

Medicine and Sorcery

If only 80 or so of the 500 medicines routinely prescribed by TCM practitioners have clinical effects that have been validated according to modern scientific criteria, how can TCM doctors bring themselves to recommend medicines that have not yet been fully evaluated on this basis?

Medicine?s origins typically overlap with those of sorcery, and TCM is not an exception. Nevertheless, about 2500 years ago, Bian Que--a physician who refused to treat patients who trusted in sorcery--began to apply the principles of clinical observation to his practice.

Why We Study Medicinal Herbs

Anything in nature has its reason to be there. The study of the interactions of plants with the human body by many generations of ancient doctors through the ages had enabled a compilation of a database of medicinal herbs with details on their effects on the human body. The value of this ?database? is evident from the successful development of several important drugs from there [see sidebar].

Modern Drugs From Chinese Herbs

Artemisia annua L. was described as an antimalarial in Compendrum of Materia Medica published in 1570. Four hundred years later, in the 1970s, artemisinine, a natural chemical isolated from Artemisia annua L., was shown to exhibit strong antimalarial properties.

Datura metel L. contains atropine, a cholinoceptor blocker.

The sources of digoxin include white and purple foxglove ( Digitalis lanata and D purpurea), Mediterranean sea onion, Strophanthus gratus, oleander, and numerous other tropical and temperate zone plants.

However, the lack of technology in olden days limited the accomplishments of TCM doctors, leaving much of what?s in their ?database? to be reevaluated and reestablished from a modern science?s point of view. Because TCM research and practice have not been interrupted for some 2500 years, the accumulated database is huge and reliable. The pioneers of TCM used to try the candidate herbs on themselves before treating their patients. Some early TCM practitioners were even poisoned by their herbs several times within a normal working day. The effects of the herbs on TCM practitioners and their patients were literally recorded to form the early pharmacological literatures--for example, the Shennong?s Pharmacopoeia--that have been attested, amended, and built on by many generations of successors, based on their clinical observations of numerous patients suffering from various kinds of diseases.

Generally, effective elements constitute about 0.1% to 10% of the dry weight of the herb. However, the TCM database provides no answer as to which natural chemicals account for the therapeutic effects of the herb, or how the natural chemicals interact with the human body and cure diseases. Therefore, TCM doctors and medical scientists like those in our research group choose to work in the area of isolation of effective natural chemicals from medical herbs and demonstration of their mechanisms of actions.

All members of our research group are trained in modern medical science. However, we assume that the way of thinking of modern medical science may undergo a vicissitude. For example, the treatment of hypertension went through several significant changes from the days of the a-adrenoceptor antagonists to that of the latest generation of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers. An important distinction between TCM and ?modern? medicine is the holistic approach inherent to TCM. In the treatment of cardiovascular diseases, the holistic approach, with the combined methodology of modern science and TCM, appeals to us.

Another reason that makes us interested in therapeutic herbs is the potential long-term harm of synthetic drugs. A case in point is the recent finding of feminized frogs in the United States, the result, it is thought, of residual estrogen in the water supply in that country. Although new synthetic drugs are closely evaluated for high specificity, high efficacy, low toxicity, and good pharmacokinetics, little attention is paid to the possibility that the chemically synthesized drugs may eventually be discharged from the human body into the environment in their original and/or metabolized forms. This is in stark contrast to regulations governing, for example, nondegradable packaging materials, which are strictly limited in many countries. Herbs, being natural and less likely than synthetic drugs to accumulate in the environment, attract our interest.

Our Area of Interest

As pharmacologists, our interest is primarily in the mechanisms and therapeutics of ischemic heart diseases, and we have been working on the cardiovascular effects of herbs according to modern scientific criteria. Our studies involve the use of a whole-cell patch clamp, an electrophysiological approach to measure the transmembrane current of a single cell, to identify the effects of herbs on the cardiovascular system. This has enabled us to identify some specific effects of compounds derived from herbs such as Folium Ginkgo (ginkgo leaf), Radix Sophorae Flavescentis (flavescent sophora root), and Salvia miltiorrhiza (salvia root) (see suggested readings).

Trends of Modern TCM Research

Because a majority of the herbs used in TCM have not been extensively evaluated, the current research trend is toward the isolation and elucidation of the chemical structure of all elements contained in the herbs. If the three-dimensional structures of the herb elements are elucidated, and a database of them can be established, it may facilitate computer-assisted imitation of docking between the herb element and physiologically important cell membrane proteins such as receptors, ion channels, and transporters. Future studies may include demonstration of the combined effects of different elements isolated from the same herb and the degradation property of the TCM elements in the environment.

In light of the promises of modern TCM research and a general preference for TCM treatment amongst Chinese communities, a clear career track in this field has taken shape. In today?s China, a new generation TCM doctors must be trained in TCM colleges where courses in modern medical science are taught along with TCM knowledge. According to a 1999 statistic published in the Health Almanac of China (People?s Health Press, 2000), there were 1,292,290 doctors and 151,600 pharmacists of ?modern? medicine in China. In addition, 337,503 doctors and 159,900 pharmacists were licensed to practice TCM. We assume that both modern medicine and TCM have their merits. TCM is evolving and benefiting from the rapid development of modern medicine and in turn may contribute as an alternative approach for treating human diseases.

Suggested readings

  • Xin-Yan Ji, Benny K-H Tan, Yi-Zhun Zhu, "Salvia miltiorrhhiza and ischemic diseases," Acta Pharmacologica Sinica 21(12), 1089 (2000)

  • Diederik Schowanek and Simon Webb, "Exposure simulation for pharmaceuticals in European surface waters with GREAT-ER," Toxicol Lett. 10;131(1-2):39-50, (2002)

  • Reinhard Lange R, Daniel Dietrich, "Environmental risk assessment of pharmaceutical drug substances--conceptual considerations," Toxicol Lett. 10;131(1-2):97-104 (2002)