ANALOGS OF KIBOFLAVIN AND FAD 



537 



Ribityl 



H,CCH. 



H3CCH; 





6, 7 -Diethyl analog 

 of riboflavin 



Ribityl 



6-Chloro analog 

 of riboflavin 



Ribityl 



I 



H,C 



A^. 



H NH, 



2, 4-Diamino-7, 8- 



dimethyl-10- 



ribityl-5, lO-dihydrophenazine 



Sorbityl 



Flavotin 



H,N 



NH, 



H,N 



Acriflavine 

 (trypaflavine, euflavine) 



NH, 



Proflavine 



CH, 



A number of analogs have been found to inhibit the growth of Lacto- 

 bacillus casei, the standard test organism: isoriboflavin, the 6-chloro and 7- 

 chloro analogs of riboflavin (Lambooy, 1955), the 2,4-diaminophenazine 

 analog (Woolley, 1944 b), and riboflavin-5'-sulfate (Egami et al., 1956). 

 Other bacteria are occasionally inhibited, for example S. aureus and Str. 

 plantarum by dichlororiboflavin (Lambooy, 1955). The acridines, proflavine 

 and 5-aminoacridine, suppress the growth of L. casei but this is not coun- 

 teracted by increasing the riboflavin concentration, so the mechanism is 



