Herbs: Challenges in Chemistry and Biology - American Chemical

Chapter 8

Need for Analytical Methods and Fingerprinting: Total Quality Control of Phytomedicine Echinacea Jatinder Rana and Amitabh Chandra Downloaded by STANFORD UNIV GREEN LIBR on July 7, 2012 | http://pubs.acs.org Publication Date: January 12, 2006 | doi: 10.1021/bk-2006-0925.ch008

Department of Analytical Services, Access Business Group, 7575 Fulton Street East, Ada, MI 49355

Increased popularity of phytoceutical products has generated interest in the benefits of products such as Echinacea as a dietary supplement. Echinacea phytomedicines and herbal preparations are widely used for the treatement of colds and influenza. Echinacea contains a variety of phytochemicals with demonstrated biological activities, which are suitable "markers" for quality assurance. The need for analytical methods for qualitative and quantitative analysis of these markers in herbal and botanical products has increased and is very challenging. Challenges in analytical method development, isolation of markers, and their identification using fingerprinting to identify different species has been used as a quality control tool for many herbal preparations.

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© 2006 American Chemical Society

In Herbs: Challenges in Chemistry and Biology; Wang, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2006.

Downloaded by STANFORD UNIV GREEN LIBR on July 7, 2012 | http://pubs.acs.org Publication Date: January 12, 2006 | doi: 10.1021/bk-2006-0925.ch008

Ill Echinacea, one of the most popular herbs in the United States marketplace is the Native American medicinal plant. In recent years, Echinacea products have been the best-selling herbal products in natural food stores in the U S (1-4). The term refers to several plants in the genus Echinacea, derived from the aboveground parts and roots of Echinacea purpurea (L.) Moench, E. angustifolia D.C., and E. pallida (Nutt.) Nutt. [Fam. Asteraceae]. Herbalists and pharmacognosists point out the irony that almost all of the scientific research on this medicinal plant has been conducted not in the United States but in Germany. Echinacea preparations have become increasingly popular in Germany since the early 1900s. The herb was first analyzed and tested for homeopathic purposes in Germany and its medical use was later investigated by Dr. Gerhard Madaus in 1938 (5). Echinacea was formerly used in the United States by Native Americans and by Eclectic physicians in the late 1800s and early 1900s. Preparations made from various plants and plant parts of the genus Echinacea constituted the topselling herbal medicine in health food stores in the United States (4). Echinacea is used for preventing and treating the common cold, flu, and upper respiratory tract infections (URIs) (5). It is also used to increase general immune system function and to treat vaginal candidiasis. The clinical literature tends to support the treatment for symptoms of colds, the flus, and URIs (6). Recent studies do not support its use to prevent URI (7). The genus Echinacea is assigned to the Heliantheae that is the largest tribe within the Compositae (Asteracea) family. The current taxonomy of the genus Echinacea, also used in the present National list of Scientific Plant Names, is based on a comparative morphological and anatomical study, according to which the genus comprises nine species and two varieties. But, only E. purpurea (L.) Moench E. angustifolia D C . and E. pallida (Nutt) is widely used as medicinal plants (7,8). The phytochemical constituents of Echinacea species range over a wide range of polarity, from the polar polysaccharides and glycoproteins, via the medium polar, caffeic acid (phenolic acid) derivatives and flavonoids to the lipophilic polyacetylenes and isobutyl amides commonly known as alkamides. The pungent property of the Echinacea roots is due to the presence of alkamides. E. purpurea herb contains caffeic acid derivatives, mainly cichoric acid (1.2-3.1% in the flowers), caftaric acid and chlorogenic acid (Figure 1); 0.0010.03% alkamides, mainly isomeric dodeca-2£,4£,8Z,10£/Z-tetraenoic acid isobutylamides (Figure 2); water soluble polysaccharides, including PS I (a 4-0methylglucoronylarabinoxylan) and PS II (an acidic rhamnoarabinogalactan), fructans. Echinacea angustifolia root contains caffeic acid derivatives, mainly echinacoside (0.3-1.7%) followed by chlorogenic acid, isochlorogenic acid, and its characteristic constituent cynarin (1,5-O-dicaffeoyl-quinic acid); flavonoids of the quercetin and kaempferol type in free and glycoside forms, including rutoside, luteolin, kaempferol, quercetin, apigenin and Isorhamnetin; polysaccharides, including inulin (5.9%) and fructans; glycoproteins comprised


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of approximately 3% protein of which the dominant sugars are arabinose (6484%), galactose (1.9-5.3%) and glucosamines (6%); 0.01-0.15% alkamides, mainly derived from undeca- and dodeca-noic acid, primarily the isomeric dodeca-2£,4£,8Z,10£/Z-tetraenoic acid isobutylamides.

R = Glucose (1,6-) & R = Rhamnose (1,3-) 1

CHLOROGENIC ACID

Figure I.: Chemical structures of Echinacea polyphenols

Dodeca-2E,4E,8Z,10E-tetraenoic acid isobutylamide

Dodeca-2E,4E,8Z,10Z- tetraenoic acid isobutylamide Figure 2. Chemical structures of major isobutylamides in Echinacea spp. Echinacea pallida herb contains caffeic acid derivatives, including cichoric acid, caftaric acid, echinacoside, verbascoside, chlorogenic acid, and isochlorogenic acid; flavonoids mainly rutoside; alkamides, mainly of the 2,4-



113 diene type with the isomeric mixture of dodeca-2£,4£,8Z,102?/Z-tetraenoic acid isobutylamides; and

Herbs: Challenges in Chemistry and Biology - American Chemical

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