Digitonin derivatives of low toxicity: potential solubilizers for lipophilic compounds

Digitoxin was modified by condensation with propylene oxide or with 1,4-butanediol diglycidyl ether in aqueous alkali, yielding products in which some of the CH2OH groups of digitonin were converted to CH2OCH2CHOHCH3 or to CH2OCH2CHOHCH2O(CH2)4OCH2CHOHCH2OH groups, respectively. These modified digitonins were very soluble in water and chloroform and effectively solubilized lipophilic compounds into aqueous solutions; e.g., 2 mg of vitamin A or 0.6 mg of cholecalciferol could be dissolved per 1 mL of 5% aqueous solutions of modified digitonins. Compared with the toxicity of digitonin (LD50 4 mg/kg iv), the toxicity of modified digitonin was greatly reduced: doses of 500 mg/kg by intravenous infusion were not lethal for mice.