Adjuvant Effects Of Eight Dammarane-type Of Ginsenosides

Adjuvant effects and structure-effect relations, as well as the haemolytic activities of eight dammarane type saponins from Panax ginseng were evaluated. Meanwhile, the adjuvant effect of Rgl+Alum was estimated, and the adjuvant mechanism of Rgl was investigated. The above results provided a basis for development and application of medicinal herbs in vaccine adjuvants.1. Evaluation of haemolytic activity of dammarane-type ginsenosidesThe haemolytic activities of Rbl and Rgl were detected, and compared with that of QA. Results demonstrated that Rb1 showed no haemolytic activity and Rg1 showed slight haemolytic effect (P< 0.05) with 5.28% haemolysis at the concentration of lmg/ml. However,100% haemolysis was observed at concentration of 8μg/ml of QA. The results indicated that ginsenosides could be safe for use as adjuvants.2. Adjuvant effects and structure-effect relations of dammarane-type saponins from ginseng rootsThe objective of this test was to characterize the adjuvant effects of protopanaxadiol saponins (Rg3, Rd, Rc, Rb1 and Rb2) and protopanaxatriol saponins (Rg1, Re and Rg2) isolated from the root of Panax ginseng C. A. Meyer. Fifty-five BALB/c mice were subcutaneously injected twice at a three-week interval with 0.89% saline or 0.89% saline containing 10μg of ovalbumin (OVA) or 0.89% saline containing 10μg of OVA plus 50μg of ginsenosides Rg3, Rd, Rc, Rb1, Rb2, Rg1, Re or Rg2 or Quil A. Two weeks after the boost, blood samples were collected for measuring specific total-IgG, IgG1 and IgG2a responses, and splenocytes were harvested for the detection of lymphocyte proliferation as well as Interferon-γ(IFN-γ) and Interleukin-5 (IL-5) production. The results indicated that OVA-specific antibody responses were significantly higher (P< 0.05) in mice immunized with OVA co-administered with Rg1, Re, Rg2, Rg3 and Rb1 but not with Rd, Rc and Rb2 (P> 0.05) when compared with the control (immunized with OVA alone). Significantly enhanced splenocyte proliferative responses to Concanavalin A (Con A), Lipopolysaccharide (LPS) and OVA (P<0.05) as well as the production of both IL-5 and IFN-y (P<0.05) stimulated by OVA were detected in mice immunized with OVA co-administered with Rg1 but not with Rb1, Re and Rg3 when compared with the control. Therefore, among the ginsenosides studied, Rg1, Re, Rg2, Rg3 and Rb1 are more potent adjuvant than the others, indicating that they are the major constituents contributing to the adjuvant activities of total ginseng saponins. Variety of ginsenosides in adjuvant activity might be attributed to the variety of molecular conformations determined by the side sugar chains attaching to their dammarane skeleton.3. Ginsenoside Rgl combined with Alum promoted a balanced Thl and Th2 immune responses to ovalbumin in mice.In present work, the adjuvant potential of Rgl and Rgl+Alum on Thl and Th2 immune responses of BALB/c mice against ovalbumin (OVA) were evaluated. Results demonstrated that Rgl showed adjuvant effects on Thl/Th2 immune responses by enhancing both IgGl (P< 0.05 or P< 0.01) and IgG2a (P< 0.01 or P< 0.001) levels, as well as DTH (delayed-type hypersensiticity) reaction (P< 0.01). Furthermore, the antigen-induced cytokine secretions (IFN-γand IL-5) in splenocyte culture were significantly enhanced by Rgl compared with OVA control (P< 0.05). Interestingly, Rg1 (50μg) combined with Alum (200μg) showed significant increase in OVA-specific antibody responses, DTH reaction and cytokine secretions (IFN-y and IL-5). In conclusion, results suggest that Rgl alone or plus Alum could be used as a safe adjuvant via up-regulating both Th1- and Th2-like immune responses.4. Possible mechanisms of adjuvant activity of RglThe aim of this study was to evaluate the effects of Rgl on mRNA levels of Toll-like receptor 4 (TLR 4) and inducible nitric oxide synthase (iNOS) in mouse peritoneal Mcp. The results showed that Rgl significantly increased the mRNA levels of TLR 4 (P< 0.01) and iNOS (P< 0.05) of Mcp treated with Rgl for 12 h. It is probably that Rgl could activte the innate immune system and showed immune modulate effects by raising the mRNA level of TLR gene.