Evaluation of the immunomodulatory properties in mice and in vitro anti-inflammatory activity of cycloartane type saponins from Astragalus species.

ETHNOPHARMACOLOGICAL RELEVANCE: Astragalus roots are used to treat leukemia and for their wound healing properties in Southeast Anatolia-Turkey. MATERIALS AND METHODS: In vivo studies to investigate the effects of two Astragalus saponins were carried out on the immune response cytokines by using six to eight weeks old male Swiss albino mice. The production of IL-1ß, TGF-1ß, TNF-α, IL-2, IL-4 and IFN-γ cytokines was determined by ELISA. The spleen and lymph nodes, isolated from the mice subjects, were analyzed to realize induction of the surface antigen productions for IL-2Rα (CD25) and CD69. In addition, their effects on the targets of inflammation such as NF κB, iNOS and NAG-1 were investigated in cell-based assays. RESULTS: The results suggested that AST VII and Mac B had positive effect on Th1 cytokine release (IL-2 and IFN-γ), and suppression on Th2 cytokine production (IL-4). The immunohistochemical results exhibited induction of both IL-Rα (CD25) and CD69 surface receptors justifying the Th1 cytokine release. The compounds did not affect NF-κB or NAG-1 activity but iNOS activity was inhibited by Mac B with an IC(50) of 156 µg/ml. CONCLUSIONS: The results show that Ast VII and Mac B create powerful immunoregulatory effects without the stimulation of inflammatory cytokines in mice, and have no significant effect on the inflammatory cellular targets in vitro.

Adjuvant effects of Astragalus saponins macrophyllosaponin B and astragaloside VII.

AIM OF THE STUDY: The present study was undertaken to evaluate the hemolytic activities of two immunomodulator Astragalus saponins [Macrophyllosaponin B (MacB) from Astragalus oleifolius DC. and Astragaloside VII (Ast VII) from Astragalus trojanus Stev.], and their adjuvant potentials on the cellular and humoral immune responses of Swiss albino mice against BSA. MATERIALS AND METHODS: The hemolytic activity of Mac B and Ast VII was determined using 0.5% rabbit red blood cell. For adjuvant activity, Swiss albino mice were immunized subcutaneously with BSA 100 µg alone or with BSA 100 µg dissolved in saline containing Ast VII (30, 60, 120 and 240 µg), Mac B (30, 60, 90 and 120 µg) or Freund's adjuvant on Days 1 and 15. Sera and splenocytes were collected 2 weeks after the last immunization for concanavalin A (Con A)-, lipopolysaccharide (LPS)- and BSA-stimulated splenocyte proliferation assay and measurement of BSA-specific antibodies in serum. RESULTS: Mac B and Ast VII showed a slight hemolytic effect, with 0.42% and 0.54% values, respectively, at the highest concentration of 500 µg/ml. Mac B and Ast VII significantly enhanced the Con A-, LPS-, and BSA-induced splenocyte proliferation in the BSA-immunized mice especially at 120 and 240 µg (P<0.001), and 60, 90 and 120 µg (P<0.05, P<0.01 or P<0.001) doses, respectively. BSA-specific IgG, IgG1 and IgG2b antibody titers in serum were also significantly enhanced by Ast VII (120 µg), Mac B (90 µg) and Freund's as compared to the control group (P<0.01 or P<0.001). Moreover, the IFN-γ and IL-4 levels in the sera were detected using ELISA two weeks after the last immunization. Ast VII and Mac B were also found to stimulate IFN-γ production such as Freund's, two weeks after the last immunization at doses of 120 µg and 90 µg, respectively, as compared to the control. CONCLUSION: Results show that Ast VII and Mac B generate important specific antibody and cellular response against BSA in mice, proving their potentials as a new class saponin adjuvant.