ANTIBIOTICS OF ACTINOMYCETES 221 



Toxicity: LD (mice), subcutaneous, > 115.7 mg/kg; intraperitoneal, >29 



mg/kg. 

 Reference: Brown R., and Hazen, E. L., Antibiotics & Chemotherapy, 3, 



1953, 818-821. 



Picromycin 



Produced by: Streptomyces felleus. 



Synonym: Similar to proactinomycin. 



Method of extraction: Extraction with ether at weakly alkaline reaction, and 

 further purification by solvent fractionation and chromatography. 



Chemical and physical properties: Basic substance having a bitter taste. Un- 

 stable. Very soluble in acetone, benzol, chloroform and ethyl acetate. 

 Moderately soluble in ether and cold methanol. Slightly soluble in 

 carbon disulfide, petroleum ether and water. [af» = +8.2 (ethanol). 

 No typical ultraviolet absorption spectrum. C26H43NO7. 



Biological activity: Active against certain gram-positive bacteria. Limited 

 activity against M. tuberculosis. Very little activity against E. coli 

 and other gram-negative bacteria. 



Toxicity: MLD (mice), intravenous, about 150 mg/kg. 



Utilization: Favorable effect upon bacterial skin infections. 



Reference: Brockmann, H., and Henkel, W., Naturwiss., 37, 1950, 138-139; 

 Brockmann, H., Genth, H., and Stufe, R., Chem. Ber., 85, 1952, 426- 

 433; Suhren, O., Med. Klin. (Munich), 46, 1951, 722. 



Pleocidin, Pleocidin A 



Produced by: Organism resembling Streptomyces lavendulae. 



Synonym: Related to streptothricin. 



Method of extraction: Adsorption on Norit A, elution with acid methanol. 

 The filtered broth may also be cleared of Ca 44 " with sodium oxalate 

 and stirred at pH 8.0 with IRC 50; the elution is carried out with HC1 

 and the final neutralization done with IR4B. Further purification by 

 chromatography on Norit A, using methanol as a developer. Pleocidin 

 A can be separated from pleocidin by greater solubility of its heli- 

 anthate. 



Chemical and physical properties: Basic, white hygroscopic powder, maxi- 

 mum stability at pH 4 to 6. 



Biological activity: Active against gram-positive and gram-negative bac- 

 teria, mycobacteria, and fungi. The ratio of Escherichia coli to Bacillus 

 sublilis is 64 for pleocidin and 4 for streptothricin. Pleocidin A possesses 

 greater diffusibility than pleocidin, and is less active by dilution assay. 



Toxicity: LD 60 (mice), intraperitoneal, 3 mg/kg. No rabbit's eye toxicity. 



Utilization: Might find use in topical application. 



