471 Ergot Alkaloids 



ergot alkaloids.'-* Ci4-Labeled indole and serine, alone or 

 together, were not incorporated. 



Another artificial culture study in which the Claviceps 

 purpurea culture was grown saprophytically on a simple 

 galactose, ammonium succinate, mineral salts, biotin me- 

 dium to which D,L-/^-C"-tryptophan was added, found that 

 the tryptophan was an efficient precursor.^' Labeling was 

 about the same throughout the range of alkaloids isolated, 

 thus suggesting a common biogenesis. Supplementation 

 with L-tryptophan increased the yield and caused the for- 

 mation of elymoclavine and agroclavine, which were not 

 formed otherwise. 



Another (non-tracer) experiment in artificial culture 

 showed no increase in total alkaloid production on supple- 

 mentation with either tryptophan, hydroxytryptophan, in- 

 dole, 5-hydroxyindole or serotonin.^'' 



The consensus of the labeling experiments seems to be, 

 however, that tryptophan is a rather direct precursor of 

 the lysergic acid skeleton. 



Apparently there is no good evidence yet concerning the 

 origin of the remainder of the skeleton. The isoprenoid 

 precursor hypothesis is under investigation. •'• ^"^ This pro- 

 posal is buttressed by the structure of the mold metabolite, 

 echinulin, which has an indole nucleus bearing isoprenoid 

 attachments. 



CH3 



\ 



C=CH— CH, 

 CH3 r 1^ 11 CH3 CH.OH 



'CU... 



H 



^ C— CH=CH. C— CH3 



CH3 CH2 1 /" 



\ I CH3 HC NH-CH3 



c=c ^ 



CH3 .CHv O 



HN 



I 

 ^C NH 



CH3 



Echinulin 



kJ.J 



> 



H 



Chanoclavine 



" Aro Garo Paul, Dissertation Abstr. 17 2143 (1957). 



i*W. A. Taber and L. C. Vining, Chem. and Ind. 1218 (1959). 



1^ Ross M. Baxter, S. I. Kandel and A. Okany, Nature 185 241 

 (1960). 



^^ A. J. Birch, B. J. McLoughlin and Herchel Smith, Tetrahedron 

 Letters No. 7 1 (1960). 



