DESCRIPTIONS OF ANTIBIOTICS 



315 



Mcthtjtylycosides: These are termed methyl neo- 

 hiosaminides B and C, and can be differentiated 

 by paper chromatography and specific rotation. 

 P'ehling's and Tollen's reagents reduced. Contain 

 primary amino groups. C12H24N2O8 : 



^ OCH3 



C6H,03(NH2)2'' 



Diaminohexose 



OH OH 

 D-Ribose 



Chemically, neomycins B and C differ only in the 

 diaminohexose (neosamine) portion of the neo- 

 biosamine portion of their molecules (I). Neos- 

 amines B and C are isomeric (1). The structure of 

 methyl neobiosaminide C, neobiosamine C, and 

 neosamine C (2) : 



CHjNHR' 



Neosamine C 

 R' = H 



Neobiosamine C: R = R' = H 



Methyl neobiosamide C: R = CH3; R' = H 



Tentative structure of neomycin: 



CeHgOaCNHj), Q 



neomycin and viomycin, streptothricin, strepto- 

 mycin, and the mild silver protein Argyrol. The 

 activity of neomycin B is greater than that of C, 

 and there are some qualitative differences between 

 their activities. Neomycin is active tn vivo against 

 a variety of infections, including those caused by 

 Neisseria intracellularis, K. pneumoniae, Fasten - 

 reiki mulfocida, H. influenzae, V. cholerae, and Pr. 

 vulgaris. It is also effective against salmonellosis, 

 plague, and anthra.x, but not promising against 

 tuberculosis or infections with gram-positive 

 cocci, except SUtph. aureus. Active on rickettsial 

 pox in pigs, and on amebiasis in rats (2). Anti- 

 fungal activity of endomycin enhanced by the 

 neomycins (4). Neamine has little biological ac- 

 tivity, being active mainly against gram-positive 

 bacteria. 



Toxicity: Subcutaneous LDin (mice) of neomy- 

 cins B and C hydrochlorides are 220 and 290 mg 

 per kg, respectively. Intravenous LD50 of com- 

 mercial neomycin as sulfate (mostly neomycin B) 

 is 26.2 to 42.5 mg base per kg. Local toxicity is 

 slight. Nephrotoxic. Causes loss of hearing (2). 

 Neamine: LD.s,, (mice) 320 mg per kg intrave- 

 nously, 1250 mg per kg subcutaneously. 



Utilization: Urinary infections refractory to 

 other antibiotics. Infantile tliarrhea. Intestinal 

 asepsis. Topical applications (.2). 



References: 



1. Waksman, S. A., ed. Neomycin. Rutgers 



Univ. Press, New Brunswick, N. J., 1953. 



2. Waksman, S. A., ed. Neomycin; its nature 



and practical applications. The Williams 

 & Wilkins Co., Baltimore, 1958. 



3. Rinehart, K. L., Jr. et al. J. Am. Chem. 



Soc. 80: 6462, 1958. 



4. Rinehart, K. L., Jr. and Woo, P. W. K. J. 



Am. Chem. Soc. «(): 6463-6464, 1958. 



5. Trai Joun-chen et al. AntilMotiki 3(2): 



27-28, 1958. 



H H 



C6H802(NH2)2---0 



NH, 



OH H 



Biological activity: Active on most gram-positive 

 and gram-negative rods, many gram-positive 

 cocci, mycobacteria, and actinomycetes. Slightly 

 active on certain algae and yeasts. Not active on 

 viruses, protozoa, filamentous fungi, or Clostridia. 

 Cross-resistance exists, in certain cases, between 



6. Kotchetkova, Ci. \'. and Popoba,0. L. Anti- 



liiotiki ] (4): 37-40, 1956. 



7. (iause, G. F., ed. The antibiotic colimycin 



and its clinical application. Moscow, 1959. 



8. Sokolski, W. T. and Burch, M. R. Anti- 



biotics & Chemotherapy 10: 157-162, 1960. 



