164 BACTERIOLOGICAL CHEMISTRY 



and 5 per cent, of tri-ethanolamine buffer at ^^H 8-2 

 yields a product which is very similar to penicillin in 

 its properties. 



Gliotoxin. — GUodadiuyn fimbriatum, when grown in an 

 agitated culture medium containing sucrose and peptone 

 at 2^H 3 to 3-5, yields gliotoxin which can be extracted 

 with chloroform. It is also formed along with fumigacin 

 by A. fumigatus in surface or submerged cultures and 

 from an unidentified strain of Penicillium. The material 

 can be recrystallised from methanol and has m.p. 221°C. 

 (decomp). It is optically active, having [aj^f — 290° 

 in ethanol, —270° in pyridine, and —255° in chloroform. 

 In ethanol containing sodium hydroxide it undergoes 

 mutarotation from [aj^-f 111° to -|- 80° after 48 hours 

 and to 0° after 5 days. Gliotoxin has an ultra- 

 violet light absorption curve similar to those of 

 trjrptophane and indole. It is a neutral substance with 

 the composition C13H14N2O4S2. It appears to be an 

 indole derivative having a third 6-membered ring at 

 positions 1 and 2. The third ring contains the second 

 nitrogen atom, which carries a methyl group, and is 

 bridged by a clisulphide group. The oxygen is present in 

 the form of hydroxyl groups. On heating with hydriodic 

 acid or with dilute alkali, gliotoxin loses its sulphur to 

 give an a-pyrazindole derivative, C13H12O2N2, m.p. 

 122°C., which is biologically inactive. The carbon and 

 nitrogen skeleton of gliotoxin is prol)ably 2 : 3-dimethyl- 

 1:2:3: 4-tetrahydropyrazino-[l : 2]-indole : — 



In a concentration of 10/tg. j)oi- ml. gliotoxin preveiits the 



