Pfizer Handbook of Microbial Metabolites 80 



composed of three acetate units, while the A part is probably 

 derived from another source related to carbohydrate biosynthe- 

 sis. It would seem as if in the case of carlosic acid the A portion 

 were derived from oxaloacetic acid, and in carolic acid from 

 lactic or pyruvic acids. 



Inspecting other structures it appears (formally at least) that 

 in zymonic acid, isolated by Stodola from many yeasts, the A 

 portion could be from tartronate. 



O 



I / il 



HO— C=^=C— CH3 HO— C=^C— C— CH3 



I ! I I i I 



HOOC— CH I C=0 CH \ C=0 



y CH3— CH2— CH z 



I " 



CH3 



Zymonic Acid Tenuazonic Acid 



HOOC— C=4=C— CH3 



I I 



CH3-(CH2)i2— CH ! C=0 



Lichesterinic Acid 

 There are other possibilities in this case, however. Tenuazonic 

 acid, a lactam similar to the tetronic acids, must surely be de- 

 rived from isoleucine and acetoacetate.* Lichesterinic acid 

 apparently is the result of a condensation between pyruvate and 

 3-oxypalmitate. Nephromopsic acid, which sometimes is found 

 with lichesterinic acid, may be a reduction product. 



I 

 HOOC— CH CH— CH3 HO— C=[^CH 



CH3— (CH2)i2— CH C=0 CH3— CH i C=-0 



\o/^ ^Y 



Nephromopsic Acid 7-Methyltetronic 



Acid 



OH 



HOOC— CH— C— CH2COOH 



I I 

 CH3— (CH2)i2— CH2 C=0 



I 

 OH 



Caperatic Acid 



It is interesting to note the co-occurrence of nephromopsic acid 

 and caperatic acid, the former being (apparently) a condensa- 

 * See addendum. 



