Echinacea glycoproteins

Of the phytochemical components in Echinacea, the glycoproteins and polysaccharide have been the least characterized. A general protocol... 

Echinacea is one of the best-selling herbal products in the United States (Brevoort, 1998) and is promoted as an immunostimulatory agent (Bauer, 1999a, 2000). The alkamides, caffeic acid derivatives (e.g., cichoric acid), glycoproteins, and polysaccharides are believed to be responsible for Echinacea s observed immunostimulatory activity. Bauer (1997) reported that the variation in alkamide concentrations of Echinacea products was due to a number of factors such as growing season, which part of the plant was utilized in the preparation of the commercial product,... 

Glycoproteins and polysaccharides are the final class of phytochemicals compounds important to Echinacea. The glycoproteins isolated from / . purpurea and / . angustifolia roots range from 17 to 30 kDa and contain 64-84% arabinose (Bauer, 1999a, 2000). Limited research has been completed on the glycoproteins, thus the reader is directed to the review by Bauer (1999a, 2000) for further information. 

A raw polysaccharide fraction of Echinacea angustifolia ( . pallida ) roots stimulated phagocytosis in mice, determined in the carbon-clearance assay, at a dosis of 10 mg/kg b.w. and also enhanced phagocytosis of human PMN in vitro by 32% at a concentration of 0.01 mg/ml [50]. Purified extracts containing a glycoprotein-polysaccharide complex exhibited B-cell stimulating activity and induced the release of interleukin 1, TNFa und IFNa,P both in vitro and in vivo [57-59]. 

Using an ELISA method which has been developed for the detection and determination of glycoproteins in Echinacea preparations [53], it was found that . pallida roots contain less glycoproteins than . angustifolia and . purpurea roots [57]. 

From pharmacological investigations it is obvious that not a single, but several constituents like the alkamides, cichoric acid, glycoproteins and polysaccharides, contribute to the immunostimulatory activity of Echinacea extracts (for summary see Tab. 1) [152,153]. Therefore the application of extracts is still reasonable and hence the native extract is regarded as the active principle for regulatory purposes by the health authorities [154]. However, standardization of these extracts is a must for a rational therapeutic application of phytopreparations [155, 156], and reproducible quality needs also to be documented from a regulatory point of view [157, 158]. 

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