CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 177 



mation has been gained concerning the approximate chemical nature of 

 others j many others are still imperfectly known. On the basis of their 

 chemical nature, the antibiotic substances may be divided as follows : 



Lipoids and various microbial extracts removed by organic solvents, such 



as pyocyanase, pyolipic acid, and others 

 Pigments, namely pyocyanin, hemipyocyanin, prodigiosin, fumigatin, 



chlororaphin, toxoflavin, actinomycin, litmocidin, and others 

 Polypeptides, comprising tyrothricin, gramicidin, tyrocidine, colicines, 



subtilin, bacillin, and actinomycetin 

 Sulfur-bearing compounds, namely the different penicillins, gliotoxin, and 



chaetomin 

 Quinones and ketones, namely, citrinin, spinulosin, clavacin, and peni- 



ciHic acid 

 Organic bases, including streptothricin, streptomycin, and proactinomycin 



Oxford (701) classified the known antibiotic substances on the basis 

 of their chemical structure. Most of the antibiotic substances can thus be 

 grouped as follows : 



I. Compounds containing C, H, and O only 



1. Ce group: C6H6O4 — kojic acid 



2. C7 group: C7H6O4 — clavacin 



3. Cg group: CgHgOe — puberulic acid 



C8H8O4 — fumigatin 

 C8H10O4 — penicillic acid 



4. Cio group: C10H00O3 — pyolipic acid 



5. Ci3 group: C13H14O5 — citrinin 



6. Ci5 group: C15H14O6 — javanicin 



7- Ci7 group: C17H20O6 — mycophenolic acid 



8. C20 group: CgoHieOe — viridin 



9. C32 group: C32H44O8 — fumigacin, helvolic acid 



Various other compounds belonging to this group have been isolated, 

 such as gladiolic acid, CnHjoOg. 



II. Compounds containing C, H, O, and N 



* I. C12 group: C10H8ON2 — hemipyocyanin 



C12H8O4N2 — iodinin 

 C10H20O2N2 — aspergillic acid 



