Preparation and Properties of Actinomycin

antibiolicus is cultivated on a medium of 1 % peptone tryptone, 0.5 % starch, 0.2 % KjHP04, 0.2 % NaCl, 0.25 % agar, in distilled water. The rapid growth at 25-35° is accompanied by the formation of a dark brown soluble pigment. After 6 to 10 days, the culture medium is extensively extracted with ether. The ether extracts are evaporated and the dry residue is treated with petrol ether. The resultant residue contains 

Actinomycin A, thus prepared, is in the form of bright red crystalline platelets, melting at 250° with decomposition. The pigment is easily soluble in chloroform, benzene, or ethanol, less soluble in acetone and hot ethyl acetate, and slightly soluble in water and ether. Actinomycin A is levorotatory [ ]d = —320° (c = 0.25% in ethanol). It possesses a characteristic absorption spectrum in visible and in ultraviolet light (612), with maxima at 4500 A and between 2300 and 2500 A. 

Actinomycin A is stable in water-alcohol solution and can be boiled without destruction for 30 minutes. However, this stability decreases quite considerably in acid media and even more so in alkaline media. 

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