Immunosuppressive flavones and lignans from Bupleurum scorzonerifolium.

Two lignans, isochaihulactone and chaihunaphthone, together with eleven known compounds were isolated from the root of Bupleurum scorzonerifolium. Their structures were established on the basis of spectral evidence. In biological testing, eugenin and saikochromone potently inhibited CD28-costimulated activation of human peripheral blood T cells.