Ginkgolides and platelet-activating factor binding sites.

Publisher Summary The chapter presents a study on ginkgolides and platelet-activating factor (PAF) binding sites. This chapter examines ginkgolide interactions with PAF binding sites in the following three different preparations: rabbit platelet membranes, gerbil brain tissue, and rabbit iris and ciliary body. Progress has been made in the formulation of a model of the PAF receptor by studies with various compounds that can specifically antagonize PAF-induced biological effects both in vitro and in vivo . Among these compounds, the unique 20-carbon cage molecules named ginkgolides have been shown to specifically inhibit PAF-induced actions, such as platelet aggregation, hypotension, bronchoconstriction, and to exert a protective effect in experimentally induced diseases, such as brain ischemia and eye inflammation. At the present time, five ginkgolides (A, B, C, M, and J) have been identified. Coded BN 52020, BN 52021, BN 52022, BN 52023, and BN 52024, respectively. The interaction of ginkgolides with PAF binding sites has been investigated in various tissues by binding studies using tritiated PAF ([3H]PAF), because high specific activity radiolabeled ginkgolides are not currently available. Ginkgolides are specific PAF antagonists isolated from the roots and leaves of the fossil tree Ginkgo biloba. The chapter states by concluding that the identification of specific PAF binding sites in various cells and tissues and their blockade by ginkgolides explains the beneficial effects of ginkgolides in numerous experimental diseases and highlights their potential as valuable therapeutic agents for man.