198 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



with those of the methyl streptobiosaminide dimethyl acetal hydro- 

 chloride reported by Brink et al. (85). The addition of picric or sulfuric 

 acid to an aqueous solution of the guanidine hydrochloride gives in- 

 soluble crystalline salts that are readily recrystallized from hot water. 

 The analytical data for the salts agree with those of a diguanidine base 

 of the composition C8H18N6O4. This compound has the same empirical 

 formula as that suggested by Brink et al. for streptidine, and is pre- 

 sumed to be identical with it. 



Streptidine sulfate was also obtained by allowing a solution of strep- 

 tomycin chloride in i N sulfuric acid to stand at 37° C. for 45 hours. 

 The sulfate was precipitated in crystalline form by adding 3 to 5 vol- 

 umes of acetone to the reaction mixture. 



Streptidine was hydrolyzed by refluxing for 48 hours with 6 N alkali 

 yielding four moles of ammonia and a new base, for which the name 

 streptamine was proposed. This base was isolated as the slightly soluble 

 sulfate by neutralizing the hydrolysis mixture with sulfuric acid and 

 adding an equal volume of methanol. The sulfate was purified by re- 

 crystallization from aqueous methanol. The hydrolysis of streptidine 

 proceeded as follows: 



CsHjsNeO^ -f 4H2O -> CoHi.NoO^ + 4NH3 -f 2CO2 

 Streptidine Streptamine 



These results appeared to establish the fact that the six nitrogen 

 atoms of streptidine are present as two monosubstituted guanidine 

 groups which are replaced by two primary amino groups in strepta- 

 mine. Further treatment with benzoyl chloride in pyridine yielded a 

 product melting at 350° to 351 ° C, the analyses of which agreed fairly 

 well for hexabenzoylstreptamine. 



Streptidine reduced two moles of periodatej streptamine, sixj diben- 

 zoylstreptamine, twoj no formaldehyde was formed from any of these 

 compounds. The fact that streptamine required six moles of periodate 

 suggested to Carter et al. (114) that the four hydroxyl and two amino 

 groups are located on adjacent carbon atoms, pointing to a cyclic struc- 

 ture, since an open chain molecule should have yielded at least two 

 moles of formaldehyde and required only five moles of periodate. 

 Streptidine and streptamine were assigned the following formula : 



