184 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



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 pigment. The solution 

 is then exhaustively extracted with 6 per cent sodium carbonate solu- 

 tion. The ether phase, on evaporation, yields gliotoxin. The sodium 

 carbonate solution is acidified and distributed several times with ben- 

 zene j 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 215-220° C, depending on the rate 

 of heating, [a]^^ =:= — 132 ± 2° (0.41 per cent in chloroform). The 

 ultraviolet absorption curve shows only strong end absorption below 

 260 m|_i with Ej^ =298 at 234 mp. Fumigacin is practically in- 

 soluble in water, sparingly soluble in cold methanol and ethanol, and 

 more readily soluble in acetone, ethyl acetate, benzene, and ether. It is 

 easily dissolved by chloroform, acetic acid, and dioxane. 



The following reactions are negative: ferric chloride. Legal, fuchsin 

 sulfurous acid, Tollens, Molisch, Rosenheim, Hammersten (for cholic 

 acid), Jaffe-Tortelli, digitonin. The Zimmerman reaction with m-dini- 

 trobenzene for ketones is strongly positive. In the Chabrol-Charonnet 

 test for bile acid (phosphoric acid and vanillin) a strong red color is 

 obtained. Likewise, the Liebermann-Buchard test gives an intense 

 blood-red color. Fehling's solution is slowly but perceptibly reduced 

 at 100° C. The formula that has been suggested is Cof)H..8-4o07. Puri- 

 fied fumigacin has recently been shown to be identical with helvolic acid, 

 isolated from a strain of A . jumigatus. 



Gliotoxin was isolated from cultures of Trichoderma, Gliocladium, 

 and A. jumigatus (459, 960, 961), as well as from other fungi (593, 

 933), the greatest activity being produced in 2 days. It was extracted 

 from the culture medium by the use of chloroform. The latter was dis- 

 tilled off, and the residue taken up in a small amount of hot benzene or 

 95 per cent alcohol, from which, on cooling, silky white needles crys- 

 tallized. It was recrystallized from benzene or alcohol. It was found 

 (965) to have a molecular weight of 347, an optical rotation of [a]^^ = 

 — 239°, and an m.p. of 121° to 122° C. It analyzed C14H16N0O4S0, 

 later shown (459) to be C13H14N2O4S0. 



