ANTIBIOTICS OF ACTINOMYCETES 211 



petroleum ether, and benzene. Maximum light absorption at 270 and 

 430 m/x. Unstable substance with maximum stability on the acid side, 

 m.p. 199-200°C with decomposition. C 2 3H 29 N09. 



Biological activity: Active mainly against gram-positive bacteria and myco- 

 bacteria. Very limited activity against the enterobacteriaceae but 

 active against Hemophilus and Brucella. Development of resistance 

 slow. Active in vivo against B. melitensis, H. pertussis, and pneumo- 

 cocci. 



Toxicity: LD 6 o (mice), subcutaneous and intravenous, about 10 mg/kg. 



Utilization: Unknown. 



Reference: Hata, T., Ohki, N., and Higuchi, T., Kitasato Arch. Exp. Med., 

 82, 1949, 229-242; J. Antibiotics (Japan), 3, 1950, 313-325; 5, 1952, 

 529-534; Sano, Y., ibid., 535-538. 



Mannosidostreptomycin 



Produced by: Streptomyces griseus. 



Synonym: Streptomycin B. 



Method of extraction: Mannosidostreptomycin can be separated from strep- 

 tomycin by chromatography over acid-washed alumina. 



Chemical and physical properties: Mannosidostreptomycin is a D-mannoside 

 of streptomycin, m.p. 178-179°C with decomposition; [a] 2 D 5 = 47° 

 in water. C27H49O17N7. 



Biological activity: Same spectrum as streptomycin but four to eight times 

 less active than streptomycin on a weight basis. In experimental in- 

 fections mannosidostreptomycin is about three times less active than 

 streptomycin. 



Toxicity: LD 6 o (mice), intravenous, 250 mg/kg. 



Utilization: None. 



Reference: Fried, J., and Titus, E., J. Biol. Chem., 168, 1942, 391-392; 

 J. Am. Chem. Soc, 70, 1948, 3615-3618; Rake, G., McKee, C. M., 

 Pansy, F. E., and Donovick, R., Proc. Soc. Exptl. Biol. Med., 65, 

 1947, 107-112. 



Microcin A, B 



Produced by: Micromonospora sp. 



Method of extraction: Extraction from broth filtrate at pH 2.0 with ethyl 

 acetate. Back extraction of ethyl acetate with phosphate buffer (pH 

 7.0). Ethyl acetate fraction contains microcin A; the buffer, microcin B. 



Chemical and physical properties: Microcin A: neutral, reddish violet, in- 

 soluble in water. Microcin B: acid, yellowish red, slightly soluble in 

 water. 



Biological activity: Active against fungi, gram-positive and gram-negative 

 bacteria. 



