ANTIBIOTICS OF ACTINOMYCETES 193 



Utilization: None. 



Reference: Berger, J., Rachlin, A. I., Scott, W. E., Sternback, L. H., and 

 Goldberg, M. W., J. Am. Chem. Soc, 73, 1951, 5295-5298. 



Antibiotic X-464 



Produced by: Streptomyces sp. 



Method of extraction: Most of the antibiotic present in the cells. Extrac- 

 tion for the mycelium with methanol, concentration in vacuo. Extrac- 

 tion of concentrate with butyl acetate, concentration in vacuo. Extrac- 

 tion of residue with petroleum ether, concentration in vacuo. Residual 

 oil partitioned between aqueous methanol and petroleum ether. By 

 successive aqueous methanol extraction most of the activity is col- 

 lected in the methanol, which is concentrated in vacuo. The residue is 

 dissolved in benzene and chromatographed over alumina. 



Chemical and physical properties: Colorless organic acid. m.p. 170-172°C 

 with decomposition. No characteristic absorption in the ultraviolet 

 light. C26H40O7. 



Biological activity: Active in vitro against gram-positive bacteria and myco- 

 bacteria. Not active in vivo against bacterial and protozoal infections. 



Toxicity: LD 6 o (mice), intraperitoneal, 2.5 mg/kg. 



Utilization: None. 



Reference: Berger, J., Rachlin, A. I., Scott, W. E., Sternback, L. H., and 

 Goldberg, M. W., J. Am. Chem. Soc, 73, 1951, 5295-5298. 



Antibiotic X-537A 



Produced by: Streptomyces sp. 



Method of extraction: Most of the antibiotic present in the cells. Extraction 

 of cell material with butyl alcohol, concentration in vacuo, washing 

 with sodium carbonate, drying to solid. Extraction of this solid in a 

 Soxhlet apparatus with petroleum ether. Concentration in vacuo, 

 crystallization from petroleum ether. 



Chemical and physical properties: Colorless organic acid. m.p. 100-109°C. 

 [a]p 6 —7.2° in methanol. Maximum light absorption at 317 and 249 

 m/x in isopropyl alcohol. Soluble in organic solvents and insoluble in 

 water. Maximum light absorption of the sodium salt at 308 and 245 

 m/x. C34H52O8. 



Biological activity: Active in vitro against gram-positive bacteria and myco- 

 bacteria. No activity in vivo against bacterial and protozoal infections. 



Toxicity: LD50 (mice), intraperitoneal, 40 mg/kg. 



Utilization: None. 



Reference: Berger, J., Rachlin, A. I., Scott, W. E., Sternback, L. H., and 

 Goldberg, M. W., J. Am. Chem. Soc, 73, 1951, 5295-5298. 



