Structure and action of saikosaponins isolated from Bupleurum falcatum L. II. Metabolic actions of saikosaponins, especially a plasma cholesterol-lowering action.

Several metabolic actions of saikosaponins isolated from the root of Bupleurum falcatum L. were examined using albino rats. Hepatic protein synthesis from leucine-14C(U) was enhanced. Glycogen content in the liver was increased, but oxidation of glucose-14C(U) in the liver was not changed. Elevation of plasma levels of cholesterol, triglycerides and p-ospholipids by cholesterol feeding was reduced. Although hepatic lipogenesis and cholesterogenesis from acetate-1-14C of glucose-14C(U) were stimulated, the elimination of i.p. injected cholesterol-4-14C from plasma was acclerated. Fecal excretion of i.p. injected cholesterol-4-14C, expressed as total-14C including bile acids-14C and neutral sterols-14C, was increased. Among the saikosaponins isolated from Bupleurum falcatum L., saikosaponins a and d, but not c, had metabolic actions as well as anti-inflammatory action. These metabolic actions and anti-inflammatory action of saikosaponins may confirm the clinical application of Bupleurum falcatum L, which has been widely used in the prescriptions of the oriental medicine, and may suggest possible mechanisms for the actions of its active principles.