Pharmacological Influence of Saikosaponins on Prostaglandin E₂ Production by Peritoneal Macrophages

Abstract

The effects of purified saikosaponins a, b₁, b₂, c and d on prostaglandin E₂ production by rat peritoneal macrophages were examined. Prostaglandin E₂ biosynthesis was stimulated by saikosaponins b₁, b₂ and d, while saikosaponins a and c were inhibitory. A mixture of saikosaponins a, c and d, of which ratio was adjusted to the same as in the crude saikosaponin fraction having anti-inflammatory effects (3:2:2, by weight), stimulated prostaglandin E₂ production reflecting strong stimulatory activity of saikosaponin d. Saikosaponin a, while inhibitory to the production of prostaglandin E₂, stimulated (³H)arachidonic acid release from pre-labeled macrophages and caused generation of a SRS-like substance in addition to the production of an unidentified substance capable of contracting isolated guinea-pig ileum in much more slow rate than synthetic leukotriene C₄ or D₄. Mechanisms of the anti-inflammatory action of saikosaponins are discussed.