Echinacea species constituents

The roots of . purpurea do not contain echinacoside, but cichoric acid (2 ,3 -dicaffeoyl tartaric acid) and caftaric acid (monocaffeoyl tartaric acid) as shown in Figures 4 and 11. Cichoric acid was first found as a major constituent in the aerial parts of Echinacea species [82, 83]. Later it was found that it is abundant also in Echinacea purpurea roots and the content has been determined by HPLC to be 0.6-2.1% [84]. Schenk and Franke recently found 0.9% in cultivated material [15]. Cichoric acid undergoes rapid enzymatic degradation (see Echinacea purpurea aerial parts, section on caffeic acid derivatives and phenolic acids) [84]. Therefore, the quality of phytopreparations needs to be thoroughly checked. For analytical methods, see also Echinacea purpurea aerial parts. 

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 three most widely used species of Echinacea are Echinacea purpurea, Epallida, and E angustifolia. The chemical constituents include flavonoids, lipophilic constituents (eg, alkamides,... 

Three species are identified as echinacear" Echinacea an-gu. lifolia. E. pallitla. and E. purpura. All are used for medicinal purposes, and they have similar properties. There are slight differences among the species witlt regard tn the anatomical distribution of active constituents. 

When dealing with the pharmaceutical quality and pharmacological activity of Echinacea preparations, it is important to distinguish between the different species, parts of the plants, and the various extraction modes. Since aerial parts and roots of Echinacea purpurea, and the roots of Echinacea angustifolia and Echinacea pallida are the most important raw materials of Echinacea phytopharmaceuticals, the constituents and immunological effects of these parts shall be especially reviewed. 

Stoll et al. [39] isolated echinacoside from the roots of Echinacea angustifolia. It is the major polar constituent and is present at a concentration of 0.3-1.7% [15, 31, 39-41]. It occurs in . pallida at a similar concentration and is therefore not suitable for the discrimination of these two species [42]. However, they can be distinguished by the occurrence of 1,3- and 1,5-O-dicaffeoyl-quinic acids (Fig. 3), which are only present in the roots of . angustifolia [31]. 

Echinacea purpurea roots have been substituted for a long time with Partheni-um integrifolium. The sesquiterpene esters, echinadiol-, epoxyechinadiol-, echinax-anthol- and dihydroxy-nardol-cinnamate, described as constituents of Echinacea purpurea roots [81], were in fact derived from the adulterant Parthenium integri-folium which was mistakenly processed at that time. Since both species contain different constituents, HPLC and TLC methods have been developed to distinguish them [32]. Parthenium integrifolium is characterized by the sesquiterpene esters (Fig. 10) which cannot be found in Echinacea roots. 

Misidentification of source plants involved in chemical analysis before 1986, except for authenticated cultivated E. purpurea, renders earlier chemical studies unreliable. Components attributed to E. angustifolia, which may instead have involved E. pallida, include flavonoid components of the leaves essential oil constituents, including echinolone, humu-lene, caryophyllene epoxide, and various polyacetylene components. Four sesquiterpene esters (cinnamates of echinadiol, epox-yechinadiol, echinaxanthol, and dUiydroxy-nardol) attributed to E. purpurea in fact do not occur in Echinacea but are constituents of Parthenium integrifolium. Chemical work by R. Bauer and coworkers at Munich and Diisseldorf now makes distinction of source species in commercial supplies possible. 

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