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Scientific Approaches to Quality Assessment of Botanical Products
Scientific Approaches to Quality Assessment of Botanical Products

A conference and workshop titled “Scientific Approaches to Quality Assessment of Botanical Products” was held at and hosted by the National Center for Natural Products Research, School of Pharmacy, University of Mississippi in Oxford, Mississippi, on September 7-9, 2004.

The purpose of the workshop was to review and discuss methods used in determining the identity, purity, quality, and strength of botanical preparations marketed as dietary supplements (DS) in the United States. The workshop is the third in a series funded cooperatively by the Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition (CFSAN) and the National Institutes of Health (NIH) Office of Dietary Supplements (ODS). Previous workshops have dealt with “The Evaluation of Basic Criteria for Authentication of Botanicals,” hosted by the National Center for Natural Products Research (NCNPR), August 9-11, 2002, and “Hepatotoxicity Assessment for Botanical Dietary Supplements,” which was held in Bethesda, Maryland, September 2003.1

The first session of the 2004 workshop, “Approaches to Establishing Identity,” dealt with quality issues and standards and was chaired by Susan Walker, MD, of FDA’s CFSAN. Gabriel Giancaspro, PhD, of the United States Pharmacopeia (USP) spoke about “Setting Standards for Botanical Quality,” discussing the various approaches used by USP to develop standards monographs in the establishment of public quality control standards for botanical materials, extracts, and dosage forms. He outlined USP’s Dietary Supplement Verification Program (DSVP), offered by USP for DS manufacturers to help ensure quality by conducting audits for good manufacturing practices (GMPs), reviewing analytical and manufacturing documentation, and testing specific products according to USP methods described in USP monographs.

Paul But, PhD, a world-renowned authority on Chinese medicinal plants from the Chinese University of Hong Kong, described state-of-the-art molecular and genetic methods in his talk, “Approaches to Establishing Identity through Molecular Means.” He focused on DNA-related techniques to determine accurate identities of botanical materials, using the relatively new genetic technique called PCR (polymerase chain reaction). He showed examples of various species of the Chinese herb stemona (i.e., Stemona >japonica, S. sessilifolia, and S. tuberosa in the family Stemonaceae) and the orchid dendrobium (Dendrobium officinale, plus D. nobile, D. chrysanthum, D. fimbriatum,D. loddigesii, and sometimes substituted with D. monilifome in the family Orchidaceae). Both of these herbal materials are utilized in traditional Chinese medicine and are described in standard monographs in the Pharmacopoeia of the People’s Republic of China; they have been frequently adulterated with a type of asparagus (Asparagus filicinus Buch.-Ham ex D. Don, Liliaceae) and a member of the genus Pholidota (Orchidaceae), respectively. As important as DNA procedures are to determine positive identity, they cannot be used as a reasonable determinant of quality, he told the audience.

The University of Mississippi’s Ikhlas Khan, PhD, the conference organizer, spoke on “The Role of Fingerprinting in Quality Assessment of Botanicals.” His presentation covered research-based initiatives needed to assure quality botanical products, including the need for authenticated plant materials and related botanical products, macroscopic/microscopic techniques to identify botanicals, reference/marker standards, putative “active” constituents, and the genetic profiling of botanicals. He also stressed the need to identify known adulterants/contaminants, misidentified species, toxic constituents, heavy metals, and pesticides. He stressed the need for the development of analytical methods for the assessment of botanicals to provide a fingerprint profile and gave examples of studies on species in the genera Ephedra (Ephedraceae) and Citrus (Rutaceae). Dr. Khan also stated that only through a thorough examination of botanical products using all the tools available to researchers will it be possible to adequately assure their quality.

Dean Gray, of the Midwest Research Institute, Kansas City, Missouri, discussed the “Development of Analytical Methods for Analysis of Complex Crude Materials and Finished Products.” He explained the significance of developing validated analytical methods and how they can be useful for determining various aspects of quality of a botanical material, i.e., in determining the levels of particular compounds that can help characterize quality. However, he noted that many of these same methods are not guarantees of proper identity. In other words, he proposed that a validated quantitative method that helps determine phytochemical quality is not necessarily appropriate for identity and that a mixture of quantitative and qualitative assays are generally necessary.

Continuing on the theme of the difficulties and challenges in characterizing chemically complex botanical ingredients and preparations, the highly renowned Ezio Bombardelli, PhD, of Indena (Milan, Italy), the world’s largest producer of chemically standardized botanical extracts, discussed “Approaches to Establishing Quality of Biologically Complex Materials.” Much of Dr. Bombardelli’s presentation covered material he discussed in his acceptance speech for a research award at the American Society of Pharmacognosy’s annual meeting in July 2004.

The panel discussion recapping the morning sessions focused on whether the gene sequencing techniques described by Dr. But can provide a way to help determine plant chemistry. For example, does a particular gene have an effect on a plant’s chemistry? The consensus answer is that this is not known; a particular gene has not yet been correlated to the presence of a particular chemical, as plant chemistry is probably the function of the presence of multiple genes.

The second session, “International Approaches to Establishing Quality of Botanical Products,” was chaired by Jeanne Rader, PhD, of FDA’s CFSAN. Jim Miller, PhD, of the Missouri Botanical Garden in St. Louis (MoBot), spoke on the value and importance of “Reference Collections and Identity of Medicinal Plants.” MoBot is one of the world’s largest research programs in plant science and one of the 6 largest herbaria in the world, with a collection of more than 6 million specimens. Dr. Miller used black cohosh (Actaea racemosa L., Ranunculaceae, syn. Cimicifuga racemosa [L.] Nutt.) as an example of how simple botanical methods can be used to help differentiate between one species of Actaea versus another: A. racemosa has much wider xylem wedges than A. pachypoda. He then explained why identification and verification of botanical identity provides unique and important data to quality control evaluations. This emphasizes the need for proper voucher specimens: a voucher is retained botanical material from a single gathering episode, collected at the same time and place.

One of the most interesting presentations from a macro perspective was delivered by the esteemed Professor Gerhard Franz of the University of Regensburg, Germany: “Quality Monographs for Herbal Medicinal Products (HMPs) in Europe.” The term botanicals is not used in the EU, where the term Herbal Medicinal Products (HMPs) is preferred. In its approach to the regulation of herbal medicines and related plant-derived preparations used for health or therapeutic purposes, the EU employs the therapeutic/medicinal concept, not the food/dietary supplement concept used in the United States, so the EU sees herbs mostly as medicinal agents, i.e., drugs. The recognition and use of the European Pharmacopoeia (EP) standards monographs are mandatory in EU countries. EP establishes a legal and scientific basis for quality control of herb materials used in phytomedicines sold in EU countries. There about 2500 total monographs in the EP; less than 10% of these monographs are HMPs. The German Pharmacopoeia (DAB) is losing importance as DAB monographs are being transferred to the EP, with about 150 DAB monographs being retained in Germany. An exception to this is the DAB Ginkgo extract monograph which is still in the DAB but not in the EP, due to debate about ginkgolic acid toxicity (other EU countries say that it’s not toxic). The fifth edition of the EP is expected to come out in 2005 (in hardcover book and CD-ROM). It still contains raw plant materials used in isolation of conventional drugs, e.g., digitalis leaf (Digitalis spp., Scrophulariaceae) for digoxin, opium poppy (Papaver somniferum L., Papaveraceae) for morphine and codeine, etc. From an EU perspective, the extract, even if it’s from a multi-component preparation (i.e., multiple herbs) is the active ingredient. He clarified the distinction between a standardized extract and a quantified extract, according to EP. Since 2000, the EP definition of standardized relies on the specific adjustment of a known active compound(s), while a quantified extract refers to one in which there is a specified level of a marker or compound that does contribute to the activity and/or efficacy of the product (e.g., hypericins in SJW). This is different from the position of the industry in the United States where standardization can refer to either the known active compound(s) or marker(s).

G.N. Qazi, PhD, Director of the Regional Research Laboratory (CSIR, Jammu-Tawi, India) spoke on “Contemporary Approaches for Quality Assessment of Botanical Drugs.” Dr. Qazi provided a broad, Indian perspective about the global market for complementary medicine and later provided some examples of herbs being clinically tested to help validate their benefits. The traditional knowledge database documenting the many uses of botanicals in various forms is the starting point in a unique validation process called “Reverse Pharmacology.” This approach is conducted by a blend of traditional and modern clinicians and groups of scientists engaged in natural drug development for degenerative disorders under the New Millennium Indian Technology Leadership Initiative (NMITLI) launched by the Indian Government. A comprehensive standardization program of botanicals as per the international standards using contemporary analytical tools then follows. The Direct phase-III clinical trials would enable introduction of safe botanicals for a large section of the Indian population in the shortest possible time frame. These validated botanical drugs would then also be offered to the global market. Dr. Qazi presented an impressive list of multi-center clinical trials in progress under this reverse pharmacology program. Traditional knowledge, modern science, and modern medicine form a golden triangle, he said, a research paradigm followed by various Indian research organizations for the rediscovery of effective botanicals.

Robin Marles, PhD, of the Natural Health Products Directorate (NHPD) of Health Canada spoke on “Quality Requirements for Canadian Natural Health Products.” He stated that about 50,000 natural health products (NHPs) are currently on the market in Canada. The regulatory target date is December 31, 2009, to bring all products into compliance and registration. He gave an overview of NHPD policies and programs and acknowledged, in particular, the American Herbal Pharmacopoeia (AHP) monographs as an excellent source of quality control information.

Yukihiro Goda, PhD, head of the Division of Pharmacognosy, Phytochemistry and Narcotics at the National Institute of Health Sciences, Japan, described the “Quality Control of Herbal Medicines in Japan.” He said that most of the herbal medicines sold in Japan are employed as Kampo medicine preparations. Kampo is the Japanese traditional medicine which is refined and improved from Chinese traditional medicine via clinical experience by Japanese practitioners. Presently, Kampo medicines are distributed mainly in the form of ready-made granules, containing a spray-dried decoction of crude drug combinations. The total retail value of the ready-made Kampo drugs is about 1 billion dollars (US). The qualities of more than 200 crude drugs themselves are controlled by standards established in the Japanese Pharmacopoeia (JP) and the Japanese Herbal Medicine Codex (non-JP crude drug standard). The qualities of the ready-made Kampo preparations are controlled by the letters of approvals from the government and the GMPs for Kampo extract preparation.

Session 3 covered the topic “Approaches to Verifying Purity and Assessing Strength” and was chaired by Edward Croom Jr., PhD, of the University of Mississippi. The first speaker, ethnobotanist Trish Flaster, president of Botanical Liaisons in Boulder, CO, expanded on the theme introduced previously by Jim Miller of MoBot. She elaborated important concepts of botany and taxonomy in her talk—“Plants Can’t Tell Us Their Name.” Ms. Flaster reviewed the use of botanical procedures for proper documentation of plant identity and described the role played by botanical voucher specimens in helping to ensure proper botanical identification. She explained the specific standard operating procedures (SOPs) for shipping and receiving vouchers. (For more on the development of an in-house herbarium of botanical voucher specimens and their role in good manufacturing practices [GMPs] for quality control, see her article on Botanical Identity in HerbalGram 63.2) Chemical data can help characterize plant material but they cannot authenticate it; for that one needs to use botanical approaches, including the use of voucher specimens.

Joseph M. Betz, PhD, from the Office of Dietary Supplements at the National Institutes of Health, used a salient case history to explain an unfortunate case of accidental poisoning from an herbal product in his presentation, “Determination of Natural Toxins in Botanical Products.” He explained the so-called “Chompers case,” whereby a product formerly sold in the US market in the late 1990s as plantain leaf (Plantago spp., Plantaginaceae) was adulterated with yellow foxglove leaf (Digitalis lanata Ehrh., Scrophulariaceae)—a result of poor quality control with some of the companies in the herb industry in both the US (importers and resellers) and in Europe (the gatherer and exporter) during those times. Dr. Betz also spoke about the availability of inexpensive tests for molds and mycotoxins. He cautioned that companies should examine every batch of high-risk materials, even from “trusted sources.”

Aviva Romm of the American Herbalists Guild (AHG) gave a characteristically lively presentation from the herbal clinicians’ and small producers’ perspectives in a talk titled, “Determination of Botanical Medicine Quality by Herbal Practitioners and Small Manufacturers.” Ms. Romm, midwife and editor of the AHG journal, represented the perspective of “herbalists/manufacturers”—practicing herbalists who produce small batches of herb products, either for dispensing to patients/clients, or more often, small businesses run by herbalists who produce herb products and are considered “small businesses.” She explained the mindset of the herbalist in viewing commercial herbal products. Most herbalists would customize formulas for their clients based on individual prescribing techniques. Formulas may be comprised of commercially obtained herbs combined by the herbalist, or professional level proprietary blends. She stressed that the herbs that are the most popular in the United States and in the international trade are not necessarily the herbs most often used by herbalists. Herbalists use traditional evidence and empiricism as a basis for their selection of herbs, even though many of these herbs may not have been well researched according to western scientific and clinical trial methods. She stated that, “Herbalists intrinsically employ a form of their own good manufacturing and good collection practices in their herbal practices.” She added that herbalists, using good organoleptic techniques (sensory evaluation, e.g., color, fragrance, taste), often do not use analytical techniques, usually preferring observational techniques.

David Bunting, herbalist and production manager at HerbPharm in Williams, OR, one of America’s leading producers of medicinal quality herbal extracts, shared some of his expertise in making medicines by explaining some important variables in different types of extracts in “Strength of Liquid and Solid Botanical Extracts: The Herb to Extract Ratio.” He explained how the extract ratio is assessed in solid extracts, liquid extracts, etc., in order to express the relative strength of an extract. The preferred method for liquid extracts is based on the weight of herb to volume of extract; although FDA regulations allow weight to weight, this is seldom done in the American industry. Tinctures generally have a denominator greater than one (i.e., dilutions of the starting botanical strength); 1:1 is a concentrated fluid extract; 1:2 is the standard for fresh plant tincture; 1:5 is the standard for dry plant tincture; 1:10 is standard for more potent botanicals. “Concentration methods must be carefully chosen to protect extract integrity and strength ratio accuracy.” Bunting made a distinction of the potency of chamomile extract (if concentrated too much the volatile oils might be compromised) and its strength. Strength ratio cannot be verified by analytical chemical means in the laboratory.

Cindy Angerhofer, PhD, Director of Botanical Research at the Aveda Corporation in Minneapolis, MN, presented on the subject of the “Evaluation of Botanical Raw Materials and Finished Products for Potency.” There are ways to quantify organoleptic assessments, she stated. Also, companies can use in vitro bioassays to measure various types of biological activity of herbs. Dr. Angerhofer, a pharmacognosist, showed an example of 2 chemotypes of rosemary oil (Rosmarinus officinalis L., Lamiaceae) in which one was able to demonstrate antifungal activity in a bioassay where the other did not, based on the presence (or absence) of specific monoterpenes. She spoke about various bioassays that deal with free radical quenching (e.g., the ORAC test), inhibition of biomarker oxidation, enzyme inhibition, inhibition of cellular response, etc.

David Pasco, PhD, a molecular biologist at the National Center for Natural Products Research at the University of Mississippi, presented some new research on Echinacea in his “Biological Standardization of Immune Enhancing Botanicals and Botanical Extracts.” Pasco proposed that the approach to standardizing botanical products by measuring bioactivity can be done in the same way as conventional pharmaceutical products such as insulin or cytokines. Examples given that demonstrated the usefulness of this approach included microalgae polysaccharides, Aloe polysaccharides (from Aloe vera [L] Burm. f., Aloaceae), and a new immune-enhancing polymer—melanin. He discussed the mucosal immune system found in the gastrointestinal tract and various methods to test the immune-stimulating activity of orally administered polysaccharide and melanin preparations on mice. He also discussed the characterization of a newly discovered polysaccharide within aloe called Aloeride. The Aloeride polysaccharide is an extremely potent activator of monocytes in vitro. “Acemannan”—normally considered the immune-stimulating polysaccharide fraction in aloe gel and juice—showed no ability to activate monocytes in vitro and has a completely different carbohydrate composition than Aloeride. Regarding melanin, Pasco said that this is a new class of immunostimulatory polymer found in many botanicals traditionally used to enhance immune function. The content of melanin within botanicals varies 2- to 4-fold while its activity can vary 100 to 10,000 times.

The last session entitled “Approaches to Characterizing Study Material,” chaired by this writer, began with a presentation by Mary Hardy, MD, of the UCLA Center for Dietary Supplement Research, who spoke on the “Challenges in Validating Study Material for Botanical Research.” She criticized the lack of specificity in the Materials and Methods section of many clinical trials reported in the conventional medical literature. Much of the herbal materials are inappropriately and inadequately described and characterized, she charged, adding that in clinical trials analyzed for a RAND review of Ayurvedic botanicals, materials were more completely described in Indian journals than journals in the US and the UK. She described how UCLA went through a lengthy and detailed process in procuring, analyzing, and documenting the identity of its botanical materials used in its in vitro, pharmacological, and clinical trials, including determination for any potential pesticide and heavy metal contamination. UCLA also employed botanical voucher samples to ensure botanical identity.

Cynthia Smith, PhD, of the National Institute of Environmental Health Sciences, discussed the “Characterization of Botanical Supplements for Safety Assessment Studies Conducted by the National Toxicology Program.” NTP reviews candidates for safety evaluations as recommended by many segments of the general public, including medical and health professional groups, trade associations, government agencies, et al. At the time of the conference, the NTP had been evaluating goldenseal (Hydrastis canadensis L., Ranunculaceae), milk thistle (Silybum marianum [L.] Gaertn., Asteraceae), kava (Piper methysticum Forst., Piperaceae), (presumably Asian) ginseng (Panax ginseng C.A. Meyer, Araliaceae), pulegone (a key compound from pennyroyal herb [Mentha pulegium L., Lamiaceae]), thujone (a key compound in wormwood [Artemisia absinthium L., Asteraceae], and ginkgo (Ginkgo biloba L., Ginkgoaceae) extract. NTP has completed safety assessment of goldenseal root and berberine (its primary active isoquinoline alkaloid). NTP/NIEHS (National Institute of Environmental Health Sciences) is not a regulatory agency; it merely attempts to provide objective information to other branches of government and scientific and medical communities. NTP reviews all old pharmacopeias, current monographs, and other authoritative sources for methods and information, and NTP is careful to purchase high-quality chemical reference standards to be used in the analyses. NTP even tests shelf-life stability. She acknowledged the American Herbal Pharmacopoeia (AHP) for its monographs from which NTP employed methods in its chemical testing programs, and Chromadex International for developing custom chemical reference standards for some of NTP’s studies. NTP is open to public suggestions regarding which botanicals it will evaluate in the future. Nominations of a botanical for review by NTP can be posted on its Web site at

The final presentation was made by R. Kenneth Marcus, PhD, of Clemson University’s Department of Chemistry and affiliate of the Center for Nutraceutical Research. He presented data on “New Methods in Heavy Metal Determination and Metal Speciation.” His bottom line: “It’s not the element that kills you; it’s the chemical form.” He tests botanical materials for total heavy metal (elemental) analysis, i.e., the first level of testing. The second level is basic elemental speciation: use of chemical separation methods to sequentially determine the levels in a botanical material. Dr. Marcus said that it is highly important to speciate the element before public health policies are set to determine allowable limits in foods or other substances.

On the day after the conference, many conference attendees met to discuss the possible development of a new Global Consortium on the Science of Botanicals, the purpose of which is “to identify and overcome the intrinsic scientific challenges of botanicals in research and commercialization.” This consortium would be intended to initially consist of numerous groups, including international overseas academic institutions, industry groups, government agencies, etc. Various academic, nonprofit, and government organizations from the US and other countries (e.g., Austria, China, India, Malaysia, Pakistan, Thailand, and Turkey) have already indicated their interest in joining the collaboration.

The fourth conference and workshop in this series is scheduled for August 2005, also at the University of Mississippi. Details are available at


1. Walker LA. Hepatotoxicity Assessment for Botanical Dietary Supplements. HerbalGram. 2005;No. 65:64-66.

2. Flaster T, Lassiter J. Quality Control in Herbal Preparations: Using Botanical Reference Standards for Proper Identification. HerbalGram. 2004;No. 63:32-37.