296 BACTERIOLOGICAL CHEMISTRY 



C = 

 OH H.CHOH /\ 



/ \ -2H2O / \ 



HC C.OH > CH C.OH 



II + II +iO, II II 



CHoOH.C CH CH2OH.C CH 



\ / \ / 



OH HO 



Penicillic and Mycophenolic Acids. — In 1890 Gosio 

 isolated moulds from diseased maize which gave rise to 

 products, giving a blue colour with ferric chloride, which 

 were thought to be toxic substances causing pellagra, 

 now known to be a deficiency disease due to lack of 

 nicotinamide. Later P. puherulum giving an acid, 

 penicillic acid, C8H10O4, and P. stoloniferum giving 

 mycophenolic acid, Ci7H2oOe, were isolated from mouldy 

 maize. Penicillic acid has been shown to have the 

 constitution y-keto- p-methoxy- S-methylene-Aa-hexenoic 

 acid which exists in both the keto and lactone forms, the 

 latter being p-methoxy- y-hydroxy- y-zsopropylidene 

 tetronic acid : — 



CH3. CHgv 



>.C0.C(0CH3) =CH.COOH ^-=^ \C.C.(0H).C(0CH3) =CH.CO 



CH,^ CH.^ I I 



'. ^ 



The constitution of mycophenolic acid has not yet been 



fully worked out, but it contains the following nucleus 



which represents the demethylated acid : — 



C.OH CO 



HOOC.C ^ 



HO.C 



C.H 



5^^12 



Tetronic Acids. — Carolic, carolinic, carlic and carlosic 

 acids, produced by P. cliarlesii when grown on glucose 

 as the sole source of carbon, are condensation products 



