HEMOLYTIC ACTIVITIES OF PLANT SAPONINS AND ADJUVANTS - EFFECT OF PERIANDRA-MEDITERRANEA SAPONIN ON THE HUMORAL RESPONSE TO THE FML-ANTIGEN OF LEISHMANIA-DONOVANI

An 87.7% (P<0.01) and 84% (P<0.001) of protection against visceral lei shmaniasis was achieved in CB hamsters and Balb/c mice, respectively, with saponin combined to the fucose-mannose ligand of Leishmania donov ani (FML). However, an undesirable haemolytic effect was described for several saponins. Aiming to improve the formulation with FML/saponin, we comparatively analysed the haemolytic potential of recently charac terized plant saponins and currently used adjuvants. The haemolytic ac tivity of steroidic saponins from Agave sisalana; Smilax officinalis a s well as commercial saponin (Riedel De Haen's), was higher than that of triterpenoid ones (Bredemeyera floribunda; Periandra mediterranea) and the Freund's complete adjuvant. The concentration resulting in 50% haemolysis was 500 mu g ml(-1) for aluminum hydroxide. The low haemol ytic effect of P. mediterranea saponin was abolished by removal of its glycidic moiety and its sapogenin fraction as well as the Freund's In complete Adjuvant were non-haemolytic within this range. Furthermore, the adjuvant effect of three doses of P. mediterranea saponin injected with the FML antigen oft. donovani, was assayed in mice, either by) t he intraperitoneal (i.p.) or the subcutaneous (s.c.) route. The anti-F ML IgG antibody levels increased and detectable levels were observed u p to 3 months in the s.c. group. The response was expanded in both gro ups after an injection with a fourth vaccine dose. The IgG response sh owed increased levels of IgG2a only in the i.p. group, while IgC2b and IgG1 but not IgG3 antibodies were higher than controls in both groups . In conclusion, the results suggest that the recently described trite rpenoid functions of P. mediterranea can be safely used as adjuvant wi th low or non-haemolytic effect. (C) 1997 Elsevier Science Ltd.