Polysaccharides, echinacea

Echinacea-polysaccharide II consists of arabino-3,6-P-galactan part, rhamnogalacturonan part and arabinan part [5], therefore it is suggested that the polysaccharide may be certain ramified region of pectic polysaccharide. 

Wagner et al. obtained immunostimulating pectic polysaccharides from plant cell culture of Echinacea purpurea [5]. From the extracellular polysaccharide... 

Roesler, I. et al., Application of purified polysaccharides from cell cultures of the plant Echinacea purpurea to mice mediates protection against systemic infections with Listeria monocytogenes and Candida albicans, Int J Immunopharmacol, 13, 27, 1991. 

Steinmuller, C. et al., Polysaccharides isolated from plant cell cultures of Echinacea purpurea enhance the resistance of immunosuppressed mice against systemic infections with Candida albicans and Listeria monocytogenes, Int J Immunopharmacol, 15, 605, 1993. 

The purple coneflower Echinacea purpura, and its close relatives, E. angustifolia and E. pallida, are the source of the herb Echinacea, which is widely popular as a nonspecific immune stimulant. These perennials are native to the prairies of North America and are now widely grown garden ornamentals. The root and aerial parts of the plant are the portions used, and the preparation s potency can be verified by the transient tingling sensation produced when it is tasted. Echinacea contains alkamides, caffeic acid esters (echinacoside, cichoric acid, caftaric acid), polysaccharides (heteroxylan), and an essential oil. Some echinacea products are standardized for their echinacoside content. In the past, adulteration with American feverfew (Parthenium integri-folium) was common. Echinacea is now sold either by itself or in combination with golden seal or zinc for the treatment of colds and influenza. 

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 effect of echinacea on the immune system is controversial. In vivo human studies using commercially marketed formulations of E purpurea have shown increased phagocytosis, total circulating white blood cells, monocytes, neutrophils, and natural killer cells but not immunostimulation. In vitro, Epurpurea juice increased production of interleukins-1, -6, and -10, and tumor necrosis factor- by human macrophages. Enhanced natural killer cell activity and antibody-dependent cellular toxicity was also observed with E purpurea extract in cell lines from both healthy and immunocompromised patients. Studies using the isolated purified polysaccharides from Epurpurea have also shown cytokine activation. Polysaccharides by themselves, however, are unlikely to accurately reproduce the activity of the entire extract. 

There is no doubt, though, that echinacea has physiological activity. Researchers have cured rodents infected with bacteria by injecting them with echinacea solutions. But this is not the same as a human taking an oral preparation. The polysaccharides, which are widely regarded as active molecules, probably do not survive digestion. Test-tube studies also indicate that a number of echinacea preparations can increase the activity of certain white blood cells that have immune function, but human evidence is harder to come by. Conflicting studies... 

Wagner et al. 33) have shown that two distinct polysaccharide fractions from Echinacea purpurea exhibited pronounced activities characterized by a high rate of phagocytosis stimulation. One polysaccharide was shown to be a heteroxylan of molecular weight 35000 and an arabinorhamnogalactan of molecular weight 450000. The main characteristics of these polysaccharides from Echinacea were the optimal solubility in water, the high content of uronic acids, and the very complex structure. 

FIG. 3 Example of polysaccharide obtained from Echinacea and cell cultures of Echinacea. Partially characterized structures (adapted from Wagner et al., 1988 Melchart and Linde, 1999). 

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

In general, polysaccharides tend to be more stable than alkamides and CAP, but their presence in Echinacea preparations is somewhat dictated by processing conditions. For example, one would expect dried plant material to contain the highest polysaccharide levels, followed by expressed juice preparation and alcohol tincture. Limited data are available regarding the effects of post-harvest handling and processing on polysaccharide levels. 

Luettig, B., Steinmiiller, C., Gifford, G., Wagner, H., and Lohmann-Matthes, M. 1989. Macrophage activation by the polysaccharide arabinogalactan isolated from plant cell cultures of Echinacea purpurea. J. Natl Cancer Inst. 81, 669-675. 

Melchart, D., Clemm, C., Weber, B., Draczynski, T., Worku, F., Linde, K., Weidenhammer, W., Wagner, H., and Sailer, R. 2002. Polysaccharide isolated from Echinacea purpurea herba cell cultures to counteract undesired effects of chemotherapy—a pilot study. Phytother. Res. 16, 138-142. 

Tubaro, A., Tragni, E., Del Negro, P., Galli, C., and Loggia, R. 1987. Anti-inflammatory activity of a polysaccharidic fraction of Echinacea angustifolia. J. Pharm. Pharmacol. 39, 567-569. 

Wagner, H., Stuppner, H., Schafer, W., and Zenk, M. 1988. Immunologically active polysaccharides of Echinacea purpurea cell cultures. Phytochemistry 27, 119-126. 

Echinacea species (coneflower, black Sampson hedgehog, Indian head, snakeroot, red sunflower, scurvy root) have become increasingly popular, particularly for the prophylaxis and treatment and prevention of cold and flu symptoms. However, the claimed efficacy of Echinacea in the common cold has not been confirmed in a randomized, double-blind, placebo-controlled trial (20) or a systematic review (21). Echinacea is claimed to have antiseptic and antiviral properties and is under investigation for its immunostimulant action. The active ingredients are glycosides (echinacoside), polysaccharides, alkamides, and flavonoids. 

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