Differential Hydrogen Exchange During Biosynthesis of Cytochalasins B and D

Sodium 2-¹³C,2-²H₃]acetate was incorporated into cytochalasin B( 1 ) by Phoma exigua and into cytochalasin D ( 2 ) by Zygosporium masonii. The ¹³C-NMR. and ²H-NMR. of the metabolites showed that most of the deuterium was lost except at carbon atoms which are in polyketide chain-initiating units.