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  • Author: U. Mothes x
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Experiments with Claviceps spec., strain SD 58, showed that L-tryptophan is a more immediate precursor of ergot alkaloids than D-tryptophan. With the exception of the carboxyl group all carbon, nitrogen and hydrogen atoms of the alanine side chain are incorporated into the alkaloids from L-tryptophan. In the case of D-tryptophan the nitrogen and the α-hydrogen of the side chain are lost during incorporation. Degradative studies confirmed that the tritium of DL-tryptophan- [alanine-2 -3H] is transferred to position 5 of the ergoline ring. The results show, that n-tryptophan is converted into the L-form via the keto acid prior to incorporation. The condensation reaction at the α-carbon of the tryptophan side chain during alkaloid biosynthesis probably involves a Waldeninversion. The mechanism of this reaction is discussed.

Bei zwei verschiedenenClaviceps-Stämmen werden die Einbauraten von markiertem 4-Dimethylallyl-tryptophan (II) und l- (β-Indolyl) -2-amino-5-methylhexen- (4) (I) in die Mutterkornalkaloide miteinander und mit denen des Tryptophans verglichen. II wird besser verwertet als I, jedoch schlechter als Tryptophan. Es wird untersucht, welche Faktoren die Verwertung der Verbindungen beeinflussen. Eine klare Entscheidung, ob I oder II Zwischenstufen der Ergolin-Biosynthese sind, kann nicht getroffen werden.

Elymoclavine-O-β-D-fructoside, a new type of ergot alkaloid, has been isolated from cultures of the ergot strain SD 58. Evidence is presented suggesting that this alkaloid is formed from elymoclavine and the sucrose of the medium by the action of invertase present in the fungal mycelia.

New experiments strengthen our earlier findings that 4-hydroxytryptophan is not a precursor of ergot alkaloids.