The inhibitory effect of Sinomenine on immunological function in mice

Abstract Sinomenine, an alkaloid isolated from the stem of Sinomenium acutum (Thunb.) Rehd. et Wils., is reported to have clinically good curative effects on arthritis and rheumatoid arthritis. Our investigation has shown that sinomenine inhibits both the humoral and cellular immunity of mice. The weights of spleen and thymus of mice treated with sinomenine (50–150 mg/kg/d, i.p.) were drastically reduced. The antisheep red blood cell antibody production and delayed‐type hypersensitivity reaction induced by sheep red blood cells were inhibited by sinomenine at doses of 50, 100 and 150 mg/kg/d; and the survival time of split‐heart transplants was also prolonged. In vitro, sinomenine suppressed the proliferation of splenic cells stimulated with LPS and ConA. These immunosuppressive actions of sinomenine afford a reasonable explanation for its clinical effects in the treatment of arthritis and rheumatoid arthritis.