Parthenium integrifolium

Some echinacea-containing products have been found to be contaminated with Parthenium integrifolium, a plant of the same family that has no known pharmacologic activity (Anonymous, 1996). 

The thin-layer chromatography (TLC) analysis of echinacea, including identification of the adulterant Parthenium integrifolium, has been described (Bisset, 1994). 

By HPLC analysis (RP 18 solvent gradient 40-80% acetonitrile/water flov 1.0 ml/min) and photodiode array detection, the different types of alkamides can easily be identified by their retention times and UV-spectra [30]. HPLC analysis is therefore especially suitable for the identification of . angustifolia roots in phytopreparations (see Fig. 2). It is also the most reliable way for the discrimination of extracts from . angustifolia and . pallida roots (see Fig. 7) [31] and for the detection of adulterations with roots of Parthenium integrifolium (Fig. 10) [32]. Also TLC can be used (silica gel solvent -hexane-ethylacetate (2 1) detection anisalde-hyde/sulfuric acid), but with less significance [30]. 

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. 

HPLC separation of a lipophilic extract from Parthenium integrifolium roots, with UV-spec-tra of the main compounds. Separation parameters see Fig. 2. From [32]. 

Bauer R, Khan lA, Wagner H (1987) Echinacea - Nachweis einer Verfalschung von Echinacea purpurea (L.) MOENCH mit Parthenium integrifolium L. Dtsch Apoth Ztg 127 1325-1330... 

Khan lA (1987) Neue Sesquiterpenester aus Parthenium integrifolium L. und Polyacetylene aus Echinacea pallida NUTT. PhD thesis, Universitat Miinchen... 

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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