The biosynthesis of tropic acid: the (R)-D-phenyllactyl moiety is processed by the mutase involved in hyoscyamine biosynthesis in Datura stramonium

Abstract

Incubations of (R)-D-phenyl[2-¹³C, ²H]lactic acid 5a and (S)-L-phenyl[2-¹³C, ²H]lactic acid 5b with transformed root cultures of Datura stramonium have revealed that the ¹³C–²H bond is retained, intact at C-3 of the tropate moiety of hyoscyamine, only in the case of the (R)-D enantiomer 5a( the deuterium is lost from the (S)-L-enantiomer 5b); therefore, it is the (R)-D-phenyllactate moiety of littorine which is the enantiomer processed by the mutase in hyoscyamine biosynthesis.