SUBSTANCES PRODUCED BY FUNGI 211 



phosphoric acid and extracted three times with ether, the combined ex- 

 tracts equalling the volume of the filtrate. The ether is evaporated to 

 one-tenth of its volume and the concentrate is shaken repeatedly with 

 saturated sodium bicarbonate solution, which removes a dark-red pig- 

 ment. The solution is then exhaustively extracted with 6 per cent so- 

 dium carbonate solution. The ether phase, on evaporation, yields glio- 

 toxin. The sodium carbonate solution is acidified and distributed several 

 times with benzene 5 the partly crystalline residue from the benzene 

 (7-12 mg. per i L of culture filtrate), on repeated recrystallization 

 from methanol, yields pure fumigacin in the form of filamentous 

 needles. Fumigacin melts with some decomposition at 2i5°-220° C, 

 depending on the rate of heating. [oi]'J — — 132 ±: 2° (0.41 per cent 

 in chloroform). The ultraviolet absorption curve shows only strong 

 end absorption below 260 mp with E 'J^^^ = 298 at 234 mp. 



Fumigacin is markedly bacteriostatic against gram-positive bacteria, 

 but not against the gram-negative forms. It is also active against tuber- 

 cle bacilli, giving complete inhibition in a dilution of i : 10,000, and par- 

 tial inhibition in i :ioo,000 dilutions (464). It is not very toxic to ani- 

 mals (126). 



Gliotoxin 



Gliotoxin is produced by various species of Trichoderma, Glio- 

 cladium, Asfergillus {A.fumigatus) and PenicilUum {P. obscurum) j2iS 

 well as various other fungi. It has been analyzed as C13H14O4N2S2 

 (474). It is rapidly produced in an acidified (/)H 3.0 to 3.5) synthetic 

 medium when grown in a submerged or shaken condition for 2 to 4 

 days. It is extracted from the culture medium by the use of chloroform. 

 The latter is distilled off, and the residue is taken up in a small amount 

 of hot benzene or 95 per cent alcohol, from which, on cooling, silky 

 white needles crystallize. It is recrystallized from benzene or alcohol. 

 It has an optical rotation of WY^ — — 2,39°, and an m.p. of 121° to 

 122° C. (991). 



Gliotoxin is frequently accompanied by one or more other antibiotic 

 substances, A. jumigatus producing as many as three others. P. ob- 

 scurum also produces one other. The removal of both from the medium 

 is brought about by extraction, at ^H 2, with benzene. The addition of 



