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Phytochemical Pattern of Echinacea Species

Each of the three Echinacea species commonly used has a distinct phytochemical profile, described briefly in this section.

Caffeic Acid Derivatives

Echinacea angustifolia Roots

Echinacoside is the main polar constituent in Echinacea angustifolia roots, where it is present at a concentration of 0.3% to 1.7% (Schenk and Franke, 1996). Echinacoside also occurs in E. pallida roots; thus it cannot be used to discriminate these two species. However, they can be easily differentiated by the presence of cynarin (1.3-dicaffeoyl-quinic acid), which is typical of E. angus-tifolia roots.

Echinacea pallida Roots

Echinacoside has been found in E. pallida roots at levels comparable to those measured in E. angustifolia roots. However, the presence (although at lower levels) in E. pallida roots of another phenolic, 6-O-caffeoylechinacoside (Cheminat et al., 1988) permits identification of this species.

Echinacea purpurea roots and aerial parts

The roots of E. purpurea are characterized by the presence of cichoric acid (2R,3R-dicaffeoyl-tartaric acid) and caftaric acid (monocaffeoyl-tartaric acid). The content of cichoric acid is in the range of 0.6% to 2.1% in fresh plant material, but decreases during manufacturing. Indeed, cichoric acid is sensitive to enzymatic degradation, and this may explain the differences in content reported for E. purpurea preparations. Cichoric acid is quite abundant also in the flowers of E. purpurea, but much less has been found in leaves and stems (Bauer, 1997).

Alkamides

Echinacea angustifolia roots

In total, 14 alkamides have been identified in E. angustifolia roots. They are mainly undeca- and dodecanoic acid derivatives, and differ in the number and configuration of the double bonds. The major representatives are 2-monoene-8,10-dynoic acid isobutylamides, and the main constituents (0.01% to 0.15%) are the isomeric dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides (8/9). However, this pair occurs also in E. purpurea roots (Bauer and Reminger, 1989) and, consequently, it cannot be used to discriminate between the two species. Nevertheless, since a number of other alkamides, namely the alkamides 12 to 19, are typical of E. angustifolia roots, identity as well as possible adulteration with Parthenium integrifolium roots can be ascertained.

A similar pattern of alkamides has been described for E. angustifolia aerial parts, but the content of 8/9 is lower (0.001% to 0.03%).

Echinacea purpurea roots

In contrast to E. angustifolia, most of the 11 alkamides identified in E. purpurea roots have a 2,4-diene moiety, representing the main representative alkamides 8/9 and the less abundant 1 to 5 and 10. These last alkamides have UV spectra different from those of alkamides (12 to 19)

OH O

OH O

8-hydroxytetradeca-9E-ene-11,13-diyn-2-one 20

8-hydroxytetradeca-9E-ene-11,13-diyn-2-one 20

OH O

8-hydroxypentadeca-9£-ene-11,13-diyn-2-one tetradeca-8Z-ene-11,13-diyn-2-one

8-hydroxypentadeca-9£-ene-11,13-diyn-2-one tetradeca-8Z-ene-11,13-diyn-2-one

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