Quantitative estimation of Holarrhena antidysenterica bark total alkaloids in crude drugs and in the body fluids of man and rat.

A turbidimetric method was developed for the quantitative estimation of the total alkaloids of kutaj bark (Holarrhena antidysenterica) in crude medicinal preparations and in the body fluids of man and rat. The alkaloids were colloidally precipitated with Dragendorff's reagent as complex salts of potassium iodobismuthate in extremely dilute solutions. The finely subdivided orange-brown precipitate gave a coloured, clear homogeneous suspension in the presence of gum arabic. Optical density of such suspensions changed linearly with the change in alkaloid concentration, when prepared within the standardized experimental conditions that included control of ion concentration and temperature of the reaction mixture. Observations revealed the reversible nature of the alkaloid-reagent reaction. Crude medicinal preparations from three different pharmaceutical sources contained varying concentrations of the alkaloids. Complete recovery of the alkaloids was possible from plasma and urine, while significant amounts of the alkaloids were lost to blood cells and faecal contents in man and rat.