Pfizer Handbook of Microbial Metabolites 



182 



COOH 



HO / 

 O 



CO~COOH 



OH 

 OH 



Labeling studies*- °' '^ show that acetate and formate are the 

 primary precursors rather than glucose. Tanenbaum, Bassett 

 and Kaplan found that stipitatic acid isolated from a Penicillium 

 stipitatum culture grown on 1-C'^-glucose had an activity about 

 five times as great as phenylalanine or tyrosine (shikimic acid 

 route) isolated from the same culture. Richards and Ferretti 

 grew Penicilliuvi aurantio-virens on media containing (a) 1-C^*- 

 acetate, (b) 2-C'*-acetate and (c) 1-C'^-glucose. Puberulic acid 

 and puberulonic acid were isolated, separated and degraded. 

 Their results, in agreement with Bentley's where the same pre- 

 cursors were used, indicate the incorporation of formate and 

 acetate as follows: 



OH OH 



@— ^ + A - 

 CH3— COOH formate 



HO 



1=0 HO-, 



/- 



® COOH 



Puberulic 

 Acid 



That is, Cj, C-., C-, and C,s of the tropolones (as numbered in the 

 puberulonic acid structure shown) are derived from the methyl 

 carbon atom of acetate, while C^,, C4 and C,j are from the acetate 

 carboxyl group carbon atom. The C- carbon atom of the trop- 

 olones was shown by Bentley" to be derived from formate. 

 The origin of the C9 carbon atoms present in puberulonic and 



* John H. Richards and Louis D. Ferretti, Biochem. and Biophys. 

 Res. Comms. 2 107 (1960). 



5 Ronald Bentley, Biochim. et Biophys. Acta 29 666 (1958). 



" S. W. Tanenbaum, E. W. Bassett and M. Kaplan, Arch. Bio- 

 chem. and Biophys. 81 169 (1959). 



