Principle of the bark of Phellodendron amurense to suppress the cellular immune response: effect of phellodendrine on cellular and humoral immune responses.

Previously we have isolated the quaternary base alkaloids, magnoflorine and phellodendrine, from Phellodendri Cortex (cortex of Phellodendron amurense Rupr., Rutaceae) as the biologically active principles to suppress local graft-versus-host (GvH) reactions in mice. In this paper, we focus on phellodendrine. Phellodendrine suppressed local semisyngeneic GvH reactions and systemic allogeneic GvH reactions in X-ray irradiated recipient mice. Phellodendrine also suppressed the induction phase of sheep red blood cell (SRBC)-induced delayed type hypersensitivity in mice and tuberculin-induced delayed type hypersensitivity in guinea pigs, but did not suppress the effector phase of these reactions. Surprisingly, phellodendrine, unlike prednisolone and cyclophosphamide, did not affect antibody production in mice to SRBC. Phellodendrine was expected to be a valuable new type of immunosuppressor against the cellular immune response.