Echinacea, standardization

Perry, N.B., Burgess, E.J., and Glennie, V.L., Echinacea standardization Analytical methods for phenolic compounds and typical levels in medicinal species, J Agric Food Chem, 49, 1702, 2001. 

Morazzoni, P. et al., In vitro and in vivo immune stimulating effects of a new standardized Echinacea angustifolia root extract (Polinacea), Fitoterapia, 76, 401, 2005. 

The purple coneflower Echinacea purpura, and its close relatives, E. angustifolia and E. pallida, are the source of the herb Echinacea, which is widely popular as a nonspecific immune stimulant. These perennials are native to the prairies of North America and are now widely grown garden ornamentals. The root and aerial parts of the plant are the portions used, and the preparation s potency can be verified by the transient tingling sensation produced when it is tasted. Echinacea contains alkamides, caffeic acid esters (echinacoside, cichoric acid, caftaric acid), polysaccharides (heteroxylan), and an essential oil. Some echinacea products are standardized for their echinacoside content. In the past, adulteration with American feverfew (Parthenium integri-folium) was common. Echinacea is now sold either by itself or in combination with golden seal or zinc for the treatment of colds and influenza. 

Finally, even if all garlic preparations were standardized to allicin content, currently the standardization practices and therefore the standardized content can vary significantly from one manufacturer to another, while product inconsistency has not been demonstrated for garlic preparations, there is literature data on the disparity of constituent content among different echinacea products (20) and ginseng products (21) (refer to Chapter 2 for further details). As such, the choice of a specific botanical product or preparation may make a difference in the presence and magnitude of a botanical product rug interaction. 

The three most widely used species of Echinacea are Echinacea purpurea, E pallida, and E angustifolia. The chemical constituents include flavonoids, lipophilic constituents (eg, alkamides, polyacetylenes), water-soluble polysaccharides, and water-soluble caffeoyl conjugates (eg, echinacoside, chicoric acid, caffeic acid). Within any marketed echinacea formulation, the relative amounts of these components are dependent upon the species used, the method of manufacture, and the plant parts used. Epurpurea has been the most widely studied in clinical trials. Although the active constituents of echinacea are not completely known, chicoric acid from E purpurea and echinacoside from E pallida and E angustifolia, as well as alkamides and polysaccharides, are most often noted as having immune-modulating properties. Most commercial formulations, however, are not standardized for any particular constituent. 

The variation in phytochemical levels between Echinacea preparations is apparent. Many researchers have suggested that standardization of phytochemicals in Echinacea products is needed. However, standardization of the products is difficult due to the complexity of the phytochemicals, the lack of understanding regarding interaction between individual phytochemicals... 

One issue not resolved by the DSHEA, specifically for botanical or herbal dietary products, is the lack of standardization of the active component. As mentioned previously, the standardization of Echinacea products is based on the level of plant material rather than one specific compound. In many cases, the specific compound responsible for the health benefit has not been fully characterized. In addition, many phytochemical constituents may participate in an observed health benefit. The lack of standardized preparations may, in fact, be responsible for the conflicting reports surrounding the biological activity of Echinacea. 

From the clinical evaluations reported to date, no clear recommendation can be drawn with regard to the effectiveness of Echinacea in clinical environments. However, the use of Echinacea as a treatment for colds or symptoms of colds are more strongly supported by clinical studies than using Echinacea as a prophylactic. The use of standardized extracts and dosages may be a better approach for evaluating Echinacea in clinical studies. 

Bauer, R. 1999b. Standardization of Echinacea purpurea expressed juice with reference to cichoric acid and alkamides. J. Herbs Spices Med. Plants 6, 51—61. 

Health Canada, 1999. Echinacea Root Labelling Standards. Health Canada Therapeutic Products Programme, Ottawa, Ontario. 

There are several limitations that lead to potential for patient harm with the current regulation of herbals under the DSHEA. First, botanical nomenclature is not standardized. Common names for herbals may vary depending on the region of the country. A single herb may have more than a dozen common names (e.g., echinacea), or one common herbal name may refer to several different species (e.g., yellowroot and snakeroot). To avoid confusion, the American Herbal Products Association (AHPA) has published Herbs of Commerce, a text of more than 500 herbs with the preferred common name, Latin binomial, and appropriate synonyms. 

Consumer Reports analyzed 19 different Echinacea products in its February 2004 issue to determine content and potency. As a primary standard they used the phenolic content as a measure of potency. The products varied with their phenolic content, some from bottle to bottle of the same manufacturer. Some of the combination products that were tested were found to have unacceptable lead levels according to California standards. Only three of the products were deemed to have adequate labeling with regards to precautions (5). 

Standardization of echinacea R44 Xiping Wang/Gaia Herbs, Inc. Prepare raw material and collect data on plant identity Prepare marker compounds and testing methods Test marker compounds to identify promising end products using different extraction methods Evaluate optimum delivery presentation and product stability... 

Cichoric acid has been the target of many analytical methods as a means to standardize Echinacea preparations. The method of Bauer (1999b) illustrates the most common method used to evaluate cichoric acid and other CADs via HPLC. A reversed-phase (LiChroCART 125-4 column) system with gradient elution was used to complete the separation within 12 min. The gradient system included water plus 0.1% orthophosphoric acid (85%) as eluent A and acetonitrile plus 0.1% orthophos-... 

The evaluation of alkamides, as an indicator for standardization, in Echinacea preparations is commonly completed using HPLC. The method of Bauer (1999b) illustrates the most common method to evaluate alkamides using reverse-phase HPLC. In this method, the lipophilic components are separated by gradient elution using water (eluent A) and acetonitrile (eluent B) linearly from 40% to 80% eluent B at 1 ml/min. The separation was completed on a C18 reverse-phase column and detection was at 254 nm. Thin-layer chromatography using silica 60 plates with... 

Echinacea is sold as a dietary supplement in the United States and as natural health products in Canada, while in Germany and many European countries, Echinacea products are sold as drugs in pharmacies (Bauer, 2000). There are a number of products on the market, which include dried herbal and root, alcohol tinctures and extracts, and expressed juice products, thus, standardization would be a difficult task. However, regulation would be less difficult because all of these products would fall under a dietary supplements category. 

The standardization of Echinacea products based on cichoric acid and alkamides has been proposed (Bauer 1999a,b Perry et al 2000, 2001). The CADs are also commonly used as marker compounds and labeled as phenolics on many dietary supplements. The main reason for standardization is that the level of the active components varies based on plant material, age of the Echinacea, and method of preparation. However, the specific compounds responsible for the immune-enhancing activity of Echinacea are not fully understood. Echinacoside has been used to standardize many preparations, but the lack of immune-enhancing activity of this component... 

Some of the most popular nutraceutical products marketed today are botanicals such as St. John s wort, echinacea, ginkgo biloba, saw palmetto, and ginseng. Unfortunately, manufacturers are not required to prove their safety or efficacy before marketing them. Dosages are not standardized. The quality of the raw source and the plant parts used are not regulated. And, unlike prescription drugs or over-the-counter medicines, there is no federal quality... 

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