DESCRIPTIONS OF ANTIBIOTICS 



169 



Table 38 

 Percentage of actinomycins contained in various mixtures (62, 77)" 



" See references to "Actinomycins," Part A. 



* Roussos and Vining (62) described a VI component in the "B type" mixture, but this is not synony 

 lous with the VI of Waksman et al. (77). 

 ' tr. = trace. 



■^ Contain.s other minor components not listed in the table. 

 ' Probably represents X^ + Xoa + another less well defined fraction. 

 ■'■ Contains other major and minor components not listed in the table. 



CH, 



The polypeptide portions of the various actino- 

 mycins contain a variety of amino acids differing 

 in their identity, arrangement, and number. 

 Physical and chemical variations observed be- 

 tween various components appear to be caused by 

 these differences. To date, all actinomycins de- 

 scribed contain L-threonine and sarcosine (Table 

 39). 



The complete structures of actinomycins I to 

 VII are shown below, and some of their properties 

 are given in Table 40 (44, 57, 63, 65, 95, 101). 



— L-valine-N — CH3 N — CHrL- valine — , 



-L-threonine L-threonine- 

 CO 



CH3 ^ CH, 

 Basic structure of actinomycins 



Variations from one actinonivcin to the other 



occur at the locations marked .4, B, ('. and D as 

 follows: 



Actinomycin I: .1 = L-proline, B = hydroxy- 

 proline, C = D = D-valine (44). 

 Actinomycin II: A = B = sarcosine, C = D = D 



valine (101). 

 Actinomycin III: . I = proline, B = sarcosine, 



(' = JJ = D-valine (101). 

 Actinomycin IV: ,1 = B = L-proline, (' — D = D- 



valine (65). 

 Actinomycin V: .1 = proline,/? = 4-ketoproline, 



(• = JJ = D-valine (95). 

 Actinomycin VI: C = D-valine, D = D-alloiso- 



leucine,.! = B = L-proline (57). 

 Actinomycin VII: r = D = D-alloisoleucine, 



A = /i = L-proline (57). 

 Actinomycins which have been characterized 

 biologically are active on gram-positive bacteria, 

 less active on mycobacteria, and inactive on fungi 

 and gram-negative bacteria, although their activ- 

 ity varies quantitatively. One report of antiviral 

 activity exists (80). Many are active on tumors in 

 animals, and certain actinomycins have been re- 

 ported to have a temporary activity on neoplasms 

 in man (21, 27, 41-43, 49, 76). All are very toxic 

 substances. Many cause splenic atrophy in animals 

 after multiple doses (CO). 



Actinomycin-producers thus far reported are all 

 members of the family Streptomycetaceae. Some 

 actinomycin-producing cultures have been found 

 under various conditions to form the compo- 

 nents of their "mixtures" in proportions differing 

 from what was considered the norm, or even to 

 vield new actinomycins altogether. A certain 



