Phytochemical variation and immunopharmacology of Panax quinquefolius L. (American ginseng)

The ethnopharmacological use of Panax quinquefolius L. (American ginseng) led to assessment of the immunostimulating properties of this eastern North American herb, and to investigate the phytochemical variation in its associated North American Araliaceae relatives. An analysis of the effect of different processing methods on ginsenoside content, a determination of the bioactive compounds in ginseng, and testing of an HPLC method were also undertaken in this thesis.; A survey of wild North American P. quinquefolius populations showed phytochemical variation exemplified by differences in the levels of major ginsenosides between populations.; The investigation of the phytochemical variation in eastern North American Araliaceae revealed the presence of ginsenosides in Aralia nudicaulis L. (Wild sarsaparilla) and Aralia racemosa L. (Spikenard). Major ginsenosides were also quantified in P. quinquefolius stem, and the ginsenoside-R_b2 was shown to be a significant saponin in P. quinquefolius leaves.; Although the results obtained for system suitability, intea-laboratory repeatability, and inter-laboratory reproducibility were generally consistent among the collaborators, the HPLC method was held not to be rigorous enough for the analysis of R_g1 and R_e. The second investigation of ginsenoside analyses examined the effect of different processing methods. The results for this investigation indicated that the most promising processing method for obtaining the highest levels of total ginsenoside content and the best quantities of R_b1, R_g1 and R_d was drying at high temperature, as performed to obtain white ginseng. A pre-steam treatment before drying to obtain red ginseng and particularly freeze-drying yielded lower ginsenoside levels.; Aqueous extracts from a four-year old cultivated root significantly stimulated the release of immunoreactive tumour necrosis factor alpha (TNFα) in culture.; The crude extractable polysaccharide fraction was analysed, and was found to contain glucose, uronic acid, galactose, arabinose, rhamnose, fucose and mannose. (Abstract shortened by UMI.)...