Haemolytic activity and adjuvant effect of notoginsenoside K from the roots of Panax notoginseng.

Notoginsenoside K (1), a saponin isolated from the roots of Panax notoginseng (Burk.) F. H. Chen, was evaluated for its haemolytic activity and adjuvant potential on specific antibody and cellular response to ovalbumin (OVA) in mice. Compound 1 showed a slight haemolytic effect, its concentration inducing 50% of the maximum haemolysis (HD50 value) being 318+/-13 microg/ml, on a 0.5% suspension of red blood cells. Compound 1 significantly increased the concanavalin A (Con A)-, lipopolysaccharide (LPS)-, and OVA-induced splenocyte proliferation in OVA-immunized mice (P<0.05, P<0.01, or P<0.001). The OVA-specific serum IgG, IgG1, and IgG2b antibody levels were also significantly enhanced by 1, especially at a dose of 25 mug compared to an OVA control group (P<0.001). Moreover, the enhancing effect of 1 on the OVA-specific IgG2b antibody responses to OVA in mice was more significant than that of Alum (AlOH gel; P<0.01). These results suggest that 1 exhibits a slight haemolytic activity and a significant adjuvant effect on specific antibody and cellular response against OVA in mice.