CHEMOTHERAPY 133 



less toxic than sulphathiazole and is active 

 against streptococci, pneumococci, staphylococci 

 and gonococci. 

 (d) Acyl. About 35 are known, of which sulpha- 



guanidine, NHa^^ Ns02.N=C , is very 



NH2 

 useful for intestinal diseases, including bacillary 

 dysentery, since it is only slowl}^ absorbed from 

 the gut, and sulphacetamide, 



NH2<^ ^SOa.NH.COCHg, 



(albucid, sulamyd) which is of value in gonorrhoea 

 and urinary infections . 

 N"^ derivatives. 



About 550 have been made. It appears that only 

 those which can break down in the body to give sul- 

 phanilamide or an active derivative of it are of chemo- 

 therapeutic use. Prontosil, prontosil soluble, 

 OH 

 CH3CO.XH 1^^ —'N^^/ ^SOj.NHj, 



proseptasine, <^ \CH2.isrH<^ \SO2.XH2, 



and soluseptasine (^ \cH.CH2.CH.NH-<^ \sO2.NH2, 



SOgNa SOsNa 



are examples. Long chain alkyl or sulphonyl derivatives 



are not broken down in this way and are, therefore, 



inactive. 



N^K* derivatives. 



The activities of substances of this type are what 

 would be expected from considerations of the effect of 



