(CHINESE) HERB NEWS
in this issue:
What is ‘turmeric?’
The past several years have seen the sudden appearance of the buzz word ‘antioxidant.’ Even a well-known one-a-day vitamin formula, manufactured by a major drug company, all of a sudden started advertising its formula as “antioxidant” despite the fact that the formula had not been changed and the advertised antioxidants (vitamins E and C and β-carotene) had always been there. It all shows the important functions of antioxidants, which used to be relegated to the domain of alternative medicine and health foods, are now considered mainstream. And other less conventional antioxidant phytochemicals other than the vitamins, such as lutein, lycopene, and curcumin, are slowly being accepted into the family of nutritional chemicals.
Because of the potential importance of antioxidants in health maintenance and disease prevention/treatment, the National Institutes of Health has awarded grants to researchers to study them. I was recently asked to recommend a source of ‘turmeric’
Dr. Leung is author of the Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics (Wiley-Interscience), which was published in 1980 and revised in 1996. He is also creator of PHYTOMED, a prototype computer database on Chinese herbal medicine developed under contract with the National Cancer Institute.
from China for such research. I believe my response was that I could not recommend one unless the requester specified what and which ‘turmeric’ was being sought, because it could be any one of several different materials, even though they all come from a handful of well-known Curcuma species. Since I am currently working on a project on reference herbs from China, and drugs derived from Curcuma spp. will be among the ones we study, I think it is appropriate time for me to provide some information on the rather complicated subject of ‘turmeric’ and/or related drugs derived from the same and related Curcuma species. Hopefully this information will be utilized by those doing research on ‘turmeric’ to source the correct materials.Because of the potential importance of antioxidants in health maintenance and disease prevention/treatment, the National Institutes of Health has awarded grants to researchers to study them. I was recently asked to recommend a source of ‘turmeric’ from China for such research. I believe my response was that I could not recommend one unless the requester specified what and which ‘turmeric’ was being sought, because it could be any one of several different materials, even though they all come from a handful of well-known Curcuma species. Since I am currently working on a project on reference herbs from China, and drugs derived from Curcuma spp. will be among the ones we study, I think it is appropriate time for me to provide some information on the rather complicated subject of ‘turmeric’ and/or related drugs derived from the same and related Curcuma species. Hopefully this information will be utilized by those doing research on ‘turmeric’ to source the correct materials.
For years, I have repeatedly stressed, both in my writings and speeches, the importance of pinning down precisely what a particular herb or herbal drug is, before subjecting it to any scientific study. Many failures in clinical trials and resulting controversies are due to the researchers’ imprecise definition of the herbal drugs they studied. One of the most common mistakes or misconceptions about botanical identity/definition of an herbal drug is to rely solely on the use of Latin binomials supported by voucher specimens. As in the story I told in the last issue of this Newsletter (Issue 37, p. 3), Latin binomials are only the first step in defining an herbal material and they are only valid when used by a competent scientist (botanist, pharmacognosist, etc.). For this reason, I advocated the identification and naming of the expert (taxonomist, pharmacognosist or herbalist) who authenticated such a botanical material in every scientific publication on natural products. Unfortunately, too often, the terms “Latin binomials” and “voucher specimens” are used, or grandiosely thrown about, by people who have no concept what these terms mean, except that they sound so impressively ‘scientific.’ There is no lack of research publications where voucher specimens were used which had nothing to do with the research at hand. A recent typical example involves feverfew research in which the authors deposited a ‘voucher specimen’ in an herbarium, which had nothing to do with the feverfew samples being analyzed: “Samples were obtained from different brands of feverfew available commercially. A voucher specimen (CH156 l1) was deposited in the herbarium of the Department of Pharmacy, King’s College London UK.” Since the samples of the commercial brands used in this study apparently were in tablet form, did the authors deposit a single bottle of one of the brands as “a voucher specimen” in the college herbarium or did they have a typical voucher specimen of Tanacetum parthenium deposited?1 In either case, their logic escapes me! There is no way their experimental results can be duplicated by other researchers without having access to all the retained samples that have been analyzed by the authors, irrespective of the “voucher specimen” (tablets or plant material) deposited by the authors.
Now back to antioxidant, specifically turmeric. But what is ‘turmeric?’ The turmeric most Americans know usually comes from India. It is the yellow cured (boiled, cleaned and sun-dried) and polished rhizome (underground stem – not the root) of Curcuma longa L. of the ginger family. It is a common spice in Asia, especially India where it is used as an ingredient in curry. Apparently, ‘the’ turmeric we use as a common spice is only derived from C. longa. It is, I repeat, the rhizome and not the root tuber of this plant, as the latter is a completely different drug and spice, called yujin in Chinese. In China, turmeric is called jianghuang (literally ‘ginger yellow’) and the plant (C. longa) whose rhizome supplies the spice/drug is also called jianghuang, which contributes to the confusion. For clarity, unless otherwise noted, the word “turmeric” used in the following will refer to the drug/spice, not to the plant.
Turmeric and yujin have quite different properties and uses. Turmeric is mainly used for menstrual problems (including hemorrhage and pain) and rheumatic pain, while yujin is more often used for jaundice, epilepsy, and depression/mania. The latter is also used as a folk remedy for treating crankiness in young children. I remember once in a while my grandmother used to cook thin slices of yujin with pig’s liver to serve as soup on the family dinner table; and only later, when I was in my teens, that I learned it was in fact, surreptitiously, for young children, and in our case, one of my much younger siblings. Of all the remedies my grandma used, this one seems to stand out for me. My siblings and I must have been a bunch of really cranky children.
Although defining an herbal material by its Latin binomial is certainly better than by its commercial name, it is far from adequate when certain Chinese herbs are concerned. This is especially true in the case of Curcuma species. The following are some whose rhizome and root tuber yield 3 different drugs – turmeric (jianghuang), yujin, and ezhu:
Drug Source Plant Plant part
(Rhizoma Curcumae Longae) *Curcuma longa L. rhizome
Yujin (Radix Curcumae) *C. longa root tuber
*C. wenyujin Y.H. Chen & C. Ling root tuber
*C. kwangsiensis S.G. Lee & C.F. Liang root tuber
*C. phaeocaulis Val. root tuber
C. aeruginosa Roxb. root tuber
C. aromatica Salisb. root tuber
Ezhu (Rhizoma Curcumae) *C. wenyujin rhizome
*C. kwangsiensis rhizome
*C. phaeocaulis rhizome
C. aeruginosa rhizome
C. aromatica rhizome
*Official in the Chinese Pharmacopoeia 2000
As one can see, turmeric, yujin, and ezhu are 3 different drugs that are traditionally used for different indications. Yet they are all derived from closely related plants of the genus Curcuma. Although the rhizome of several Curcuma species constitutes ezhu, only the rhizome of C. longa is turmeric. Turmeric and ezhu have similar yet distinctly different chemical compositions; and in the Chinese Pharmacopoeia, tumeric (jianghuang) is specified to contain at least 7.0% (ml/g) volatile oil while ezhu only a minimum amount of 1.5% (ml/g). These minimal levels of volatile oils were established following analyses of different commercial samples of the 2 drugs from different growing regions (Fujiang, Sichuan, and Guangxi): 21 samples of jianghuang (turmeric) contained volatile oil ranging from 5.2% to 14.5% (average 8.0%) and 34 samples of ezhu contained 0.7% to 4.9% (average 1.41%) of volatile oil.2 On the other hand, the volatile oil content of yujin (the root tuber of Curcuma spp.) is in general lower than that in turmeric and ezhu, ranging from 0.1% to 1.5%.4
Drug Volatile oil (ml/g)
Turmeric (Rhizoma Curcumae Longae) 5.2% - 14.5%
Ezhu (Rhizoma Curcumae) 0.7% - 4.9%
Yujin (Radix Curcumae) 0.1% - 1.5%
Although most of the reports on chemical investigations of ezhu and yujin are found in the Chinese literature, much of the chemical literature on turmeric is in English, which can be readily accessed elsewhere. Consequently, I have only included the Chinese literature in this report.
The major compounds present in the volatile oils include turmerone, ar-turmerone, curzerenone, cineole, curdione, germacrone, borneol, and curcumol, among many others.3 Their proportions differ among the 3 drugs. In addition to the volatile oil, other important compounds include the curcuminoids, with curcumin (a strong antioxidant and a yellow coloring agent) as the major one. The concentration of curcumin is highest in turmeric, at between 2% and 4%, and lowest in yujin at about 0.1%,4 while that of ezhu (rhizome of Curcuma spp. other than C. longa) lies somewhere between those of turmeric and yujin.
Considering the 3 drugs being derived from such closely related plants and/or plant parts, it’s not surprising to discover that their reported chemistry is often complex and confusing. I suspect much of the complexity and confusion, as in many natural products, can be traced back to the wrong identity of the herb being studied, which led to wrong conclusions. Add to that the innate and environmental factors influencing the chemical profiles of volatile oils, and we have an extremely complex problem on our hands. While the difference in chemical components can be fairly well defined between the root (yujin) and the rhizome (turmeric and ezhu), it is much more difficult to differentiate among the rhizomes from different Curcuma species, such as C. longa (turmeric) vs other Curcuma species (ezhu). In addition, the neglect of attention to whether one is studying the fresh, dried, or boiled and dried materials, further complicates the matter, because the components present in any one of these are certainly different from those of the other, especially in their volatile oils and more labile compounds.
In Western countries, turmeric is used as a spice and colorant primarily in foods. Because of its intense yellow color (due primarily to curcumin), it is frequently used as a coloring agent in curry, pickles, and prepared mustard. In Asian countries, especially India and China, turmeric is also used as a medicine. In China, while turmeric and ezhu have similar indications (menstrual difficulties, amenorrhea, abdominal mass, etc.) they also have different ones. Thus, rheumatism, shoulder pain, and pain due to traumatic injuries are usually treated by turmeric, while abdominal pain caused by indigestion and early uterine cervix cancer are treated by ezhu. On the other hand, the major indications of yujin are depression, mania, jaundice, and epilepsy which are different from those of the other 2 drugs.
The history of turmeric in traditional Chinese medicine can be traced back to its first written record in the Xin Xiu Ben Cao (659 AD)[also known as Tang Ben Cao, compiled by court physicians and is probably the first official pharmacopoeia in the world] during the Tang Dynasty, while that of ezhu to the 5th century (Lei Gong Pao Zhi Lun)[Lei Gong’s Treatise on Materia Medica] and yujin to the Yao Xing Lun (951-960 AD)[Treatise on the Properties of Materia Medica]. Their properties and uses have been developed through practical clinical experience over a long period of time and have not been arbitrarily assigned. For this reason, when we investigate herbs like these, their traditional properties, methods of preparation and administration, and indications must be carefully considered. We cannot afford to be sloppy by simply considering the plant species (or genus) as the herbal drug, without specifically defining the part used or how it is prepared. Here are a few other such examples where their precise identification and definition are frequently lacking: Asian ginseng root (yang properties) vs ginseng leaf (yin properties) – not just ‘ginseng,’ unless it has already been earlier defined; ephedra stem (causes perspiration, also has stimulant effects due to ephedrine) vs ephedra root (stops perspiration, contains no ephedrine); aloe vera gel (healing gel with no cathartic principles such as aloins) vs aloe latex (cathartic drug containing aloins used in laxatives); and cured fo-ti (specially prepared Polygonum multiflorum root – a tonic) vs raw fo-ti (dried P. multifllorum root – a laxative and detoxicant, many times more toxic). Another, much more dramatic, example is the common yew (also known as English or American yew). While its red fruit pulp is edible, chewing on a small twig may easily kill a child. Yet both the fruit and the twig can be correctly identified by its Latin binomial, Taxus baccata L. Hence, per the deficient logic so far used in reporting research in CAM materials by many scientists, we could say that the English yew (Taxus baccata) is edible!
(1) N.J.C. Bailey et al., “Multi-Component Metabolic Classification of Commercial Feverfew Preparations via High-Field 1H-NMR Spectroscopy and Chemometrics,” Planta Medica, 68:734-738 (2002); (2) Bureau of Drug Administration, Chinese Ministry of Health and Chinese Institute for the Analyses of Drugs and Biologicals, Eds., Modern Practical Herbal, Vol. 1, People’s Health Press, Beijing, 1997, pp. 553-559, 587-593; (3) W. Tang and G. Eisenbrand. 1992. Chinese Drugs of Plant Origin. Springer-Verlag, New York, pp. 401-415; (4) Bureau of Drug Administration, Chinese Ministry of Health and Chinese Institute for the Analyses of Drugs and Biologicals, Eds., Modern Practical Herbal, Vol. 1, People’s Health Press, Beijing, 1997, pp. 531-539.
Use of Latin drug names
Most of this problem of nonspecific definition of herbal materials can be alleviated, if not eliminated, by returning to the use of Latin pharmaceutical names. I don’t know why this fell out of favor during the past few decades in the United States. Could it be because we have been sidetracked by pursuing active principles during this time and found it no longer necessary to specifically name the plant part? After all, as long as one can obtain, say, ephedrine from an Ephedra species, what does one care which part of the plant it comes from? And for that matter, which plant species yields it? However, natural medicines have recently made a comeback and are here to stay. Unfortunately, most modern scientists trained in botany and pharmacognosy have no training and experience in the practice of traditional herbal medicine. They may be excellent botanists or phytochemists, but they don’t have the relevant comprehensive training and knowledge to deal with herbal medicines except using them as raw material sources for pharmacologically active chemicals. The most relevant modern field appears to be ethnobotany, pioneered by the late Dr. Richard Evans Schultes. Since most of the research and subjects in this field relate to jungle medicines, it is imperative to be able to return to the same location and collect the same plant material, should preliminary chemical and pharmacological results indicate it to be promising as a modern pharmaceutical agent, hence the ‘voucher specimen,’ deposited in a reputable herbarium. This system was pioneered by Dr. Schultes, and, for the past 4 to 5 decades, has served us well as the gold standard in phytochemical research. However, this system does not address the needs of traditional herbal medicines of the Old World such as China and India where the resources of herbal medicines are well documented and a single plant species often supplies 2 or more drugs that are sometimes very different, or different plant species supplying the same drug. This Latin-binomial-and-voucher-specimen system can only serve as one of several elements for defining a particular herbal drug. Consequently, in the current scientific research in the validity of traditional herbal medicines, just assigning an herbal drug a Latin binomial and depositing a voucher specimen of the plant in an herbarium is not enough and often is not even relevant. We must specific clearly from what part of the plant and how it has been prepared. It appears that we are the only major country in the world which does not use Latin pharmaceutical names. China does, and so does Germany. It’s time we realized the importance of plant parts in modern CAM research and relearned Latin drug names and started to use them in our research and publications in this field.
I goofed. In Issue 36, I
referred to lycium fruit in Chinese pin-yin simply as gouqi 3
times. It should be gouqizi (zi meaning fruit). I don’t
know how I did that, especially it’s such an obvious thing. I have to
eat humble pie for this. Which again shows how easy it is for one to
make a mistake in the definition of an herbal drug material.