Pfizer Handbook of Microbial Metabolites 460 



H 



in which R — CH — CH — CHO is any of several sugars. 



OH OH 



It may be that other derivatives of anthranihc acid can 

 participate in this route, too. For example 5-hydroxyan- 

 thranilic acid would give rise to the 5-oxyindole derivatives 

 found in nature. It is notable that this acid is a growth 

 promoter for an Escherichia coli mutant.^ 



Ascorbigen, a bound form of ascorbic acid isolated from 

 plants of the cabbage family, has one of the structures:* 



CH2— C^=CH CH2— C=CH 



oa< > CD 



H 



HO— C CH or H CH C— OH 



/ \ 



CHo— CH— CH C=0 0==C CH— CH— CH2 



OH OH \^/ \^/ OH OH 



O 



Ascorbigen 

 (alternate structures) 



The presumptive precursor is 3-indolylacetol, analogous to 

 an intermediate in histidine biosynthesis, and it is interest- 

 ing to speculate as to whether this is an offshoot of the 

 biosynthetic route to tryptophan or whether it is formed by 

 way of tryptophan. 



The mold product, echinuhn, has an unusual structure, 



apparently involving the indole synthesis, terpenoid and 



amino acid precursors. Gliotoxin, on the other hand, is 



almost entirely derived from amino acids, and it could 



have been classified as a polypeptide. C"-Labeling studies 



have demonstrated the following biosynthetic pathway for 



gliotoxin : ^ 



3H. Niemer and A. Oberdorfer, Z. physiol. Chem. 308 51 (1957). 



■* Z. Prochazka, V. Sanda and F. Sorm, Coll. Czech. Chem. Comm. 



22 654 (1957). 



s J. A. Winstead and R. J. Suhadolnik, J. Am. Chem. Soc. 82 1644 

 (1960); R. J. Suhadobiik, A. Fischer and J. Wilson, Federation Proc. 

 19 8 (1960). 



