DE4138624

An extract is derived from a mixture of the bark of the genus Phellodendron and the defatted seed of the genus Croton and has excellent therapeutic activity in treating various disorders of the immune system. The extract is obtained by extracting the mixture with an organic solvent, filtering the resulting mixture to separate a residue, extracting the residue with hot water to obtain a water soluble solution, concentrating the solution under reduced pressure and saturating vapor pressure, and removing the resulting precipitates from the solution. If necessary, the obtained solution is again extracted with an organic solvent, the resulting organic solvent and water soluble layers separated, and the water soluble layer purified and lyophilized to obtain a yellowish brown powder which can be used as the effective ingredient in a pharmaceutical composition for treating a wide range of immune system disorders.