In vivo evaluation of immunomodulatory properties of crude extracts of Echinacea species and fractions isolated from Echinacea Purpurea

摘要

This thesis describes the in vivo evaluation of orally administered extracts of Echinacea species, and fractions obtained from Echinacea purpurea for specific immunostimulatory function induced in Balb/c mice by immunization with microbial vaccines. Two vaccines were used for this purpose in this study. The first vaccine used consisted of whole-cell formalin-killed Salmonella typhimurium vaccine, which is known to induce production of specific antibodies but no delayed-type hypersensitivity response considered as an indicator of the cell-mediated immune response. The second vaccine was a commercial acellular pertussis vaccine (DTaP) consisting of inactivated diphtheria and tetanus toxoids and native or inactivated virulence factors of Bordetella pertussis (the etiological agent of whooping cough) which is known to induce a humoral immune response but with controversial reports about performance in the induction of cell-mediated immunity. Both vaccines were administered intraperitoneally, whereas the herbal extracts and fractions were administered by oral gavage. The phytochemical profile of the ethanolic extracts of Echinacea purpurea, Echinacea pallida, Echinacea angustifolia and one commercial product 'Echinacea Triplex' and three fractions prepared from Echinacea purpurea, namely polysaccharides, phenolics and alkylamides, was determined by thin-layer chromatography, high-performance liquid chromatography and/or by chemical analytical techniques. Statistically significant increases in specific anti-Salmonella typhimurium serum antibody were obtained for the Echinacea purpurea, Echinacea angustifolia and Echinacea Triplex [Trade Mark] treatment groups, and also for groups receiving treatment with fractions obtained from Echinacea purpurea, namely, polysaccharide, alkylamide and phenolic fractions. Statistically significant increases in the anti-B pertussis serum antibodies were also obtained in the young Echinacea Triplex [Trade Mark] group vaccinated with the DTaP vaccine. Significant enhancement of serum interleukin-12 titres was observed in the Echinacea Triplex [Trade Mark] as well as the phenolic fraction treatment groups which were vaccinated with killed Salmonella typhimurium vaccine. Of the groups vaccinated with the DTaP vaccine, only Echinacea Triplex [Trade Mark] displayed statistically significant increases in mean interleukin-12 titre compared to the placebo in both young and old groups, however Echinacea purpurea, and Echinacea angustifolia both displayed significant increases in mean interleukin-12 titre in the young treatment mice. Increases in interferon-gamma levels in mice orally dosed with phenolic, polysaccharide or alkylamide fractions of Echinacea purpurea and vaccinated with the killed Salmonella typhimurium vaccine were also observed, however these need to be repeated for confirmation, and statistical analysis.