キラヤサポニン経口投与による自然免疫の活性化効果

Abstract

Quillaja saponin (QS) is a food ingredient that contains triterpenoid saponins extracted from the cortex of the South American tree (Quillaja saponaria Molina), a member of the family Rosaceae. Aqueous extracts from the bark of the tree have world widely been used as an emulsifier and a foaming agent, par-ticularly in soft drinks. The present study examined an immunological function of QS as an activating agent for macrophage that is a principal phagocyte in natural immunity to prevent host from infectious pathogens. After 24 hours of oral administration of QS to mice (dose:0.5 mg/kg), both chemotactic and phagocytic activities of the macrophage prepared from either spleen cells or peritoneal exudate cells of mice tested were increased by 2-7 times in comparison to those of control mice. In addition to these results, the mice orally administered the QS shown much higher survival rate for 5 days (80%) than that of control mice (30%), when these mice were infected withE.coli (C11 strain) by intraperitoneal injection after 24hours of the oral administration of the QS. Since QS is a food additive used in the food industry, these results in the present study might lead to develop new physiological functional foods that activate natural immunity. Thus, taking foods containing QS might prevent human, especially elder people whose natural immunity is weaken by aging, from many infectious diseases.