Abstract

Saponins (designated SP) were isolated and purified from the sepals of the mature fruit ofPhysalis alkekengi L. var. francheti (Mast.) Makino which is a traditional Chinese medicine herb. Immunologic enhancement of the SP was evaluated in this paper. Male ICR mice were immunized subcutaneously with ovalbumin (OVA) alone or with OVA containing SP in doses of 0.63, 1.25, 2.50 mg/kg body weight (BW), or QuilA in doses of 0.5, 1.0 mg/kg BW 2 times at 14-day interval. The mice were sacrificed two weeks after the last immunization to analyze humoral and cellular immunity. Delayed-type hypersensitivity (DTH) response was further detected. The results showed that SP (1.25 mg/kg BW) significantly enhanced OVA-specific antibody titers (IgG, IgG1, IgG2b) in serum, the concanavalin (ConA), lipopolysaccharide (LPS), OVA-induced splenocyte proliferation, proportions of CD4⁺ and CD8⁺ T lymphocytes in spleen, delayed-type hypersensitivity (DTH) response when compared with OVA-injected mice (P<0.05 or P<0.01). More importantly, haemolytic activity assay indicated SP had lower haemolytic effect than QuilA. Therefore, SP evoked both humoral immunity and cellular immunity, and can be considered as a promising adjuvant eliciting both Th1 and Th2 responses to improve the efficacy of vaccine.

Key words: Herbal medicine, saponin, humoral response, cellular response, adjuvant.

Abbreviation

OVA, Ovalbumin; SP, saponin purified from the sepal of Physalis alkekengi L. var. francheti (Mast.) Makino fruit; OVA/QuilA (0.5, 1.0), ICR mice immunized with OVA (5 mg/kg body weight) and QuilA 0.5, 1.0 mg/kg body weight respectively; OVA/SP (0.63, 1.25, 2.50), ICR mice immunized with OVA (5 mg/kg body weight) and SP 0.63, 1.25, 2.50mg/kg body weight respectively; IFT, increase in footpad thickness.