CHEMICAL NATURE OF ANTIBIOTICS 



51 



Aureothricin-type Coiiipoiinds 



Three antibacterial and antifungal anti- 

 biotics have the same molecular skeleton, 

 composed of two rings formed of five atoms 

 of carbon, two of sulfur, and one of nitrogen. 

 The nitrogen-containing ring is of the 

 pyrrolidine type: 



,S R 



S 



/ 



\- 



Aureothricin 



Thiolutiii : 



Ri 



R = NHCOCH.CH, 



R, = CU, 



R = NHCOCH:, 



]{, = CH;, 



Holomyciii: R = NHCOCH3 

 R, = H 



Aurcothricin and thioiutin differ only in one 

 C'Ho group in the side chain R. Holomycin 

 is des-X-methyl thioiutin. Acid hydrolysis 

 of aurcothricin and thioiutin yields a weak 

 amine, pyrrothine (CeHeXoOS^). The hy- 

 drolysis of holomycin yields des-N-methyl- 

 pyrrothine, which is called holothin and 

 which has some antibiotic activity of its 

 own. 



Other sulfur-containing compounds of dif- 

 ferent types were isolated from cultures of 

 actinomycetes. They include lavendvilin 

 (C49H6:i6i8Ni3S:0, suifactin {C^rjUio^HOS-.d, 

 thiostrepton (7.4 per cent S), and sulfocidin. 

 Thioaurin (Ci4Hi2X404vS4) is an orange- 

 yellow substance active against gram-posi- 

 tive and gram-negative bacteria but not 

 against fungi. 



Compounds Containing a Purine or a 

 Pyriniidine Base 



A few products of actinomycetes contain a 

 purine nucleus. They include puromycin, 



nucleocidin, psicofuranin(% and the angust- 

 mycins. Thi'ee of these substances, angust- 

 mijcui (\ antibiotic U 9586, and psicofura- 

 nine, are presum(>d to have the same struc- 

 ture: 



NH., 



N 



-N 



N N 



y^ 



OHCHo 



>— CH.CJH 



OH OH 



Their molecule contains two moieties, 

 adenine (()-aminoj)urine) and the keto- 

 hexose, D-psicose. The special configuration 

 of the atoms in the molecule of these three 

 compounds must vary from one to the other, 

 since their biological activity differs. Angust- 

 mycin C has no known biological activity. 

 Antibiotic U OoSl) has some activity against 

 bacteria and tumors, and psicofuranine has 

 some activity against tumors and liacteria 

 in nro. In vitro antil)acterial activity was 

 demonstrated when a special medium con- 

 taining liver extract was used. 



Anduxtmt/cin A differs from the previous 

 compounds in \hv sugar attached to the 6- 

 amin()i)urine, which is called angustose: 



O 



^— CH:, 

 J— OH 



OH 



OH 



Angustmycin A is active mainly against 

 mycobacteria. 



Tubercidin and toi/ocami/cin are similar 

 compounds with an adenine and a D-ribose 

 moiety. 



Pnromi/cin has a more complicated mole- 

 cule. It is composed of three moieties: (1) 

 G-dimethylamino purine, (2) D-8-amino- 

 ribose, and {'^) o-methyl-L-tyrosine: 



