BIOSYNTHESIS OF CONIUM ALKALOIDS USING CARBON-14 DIOXIDE . KINETICS OF 14C INCORPORATION INTO KNOWN ALKALOIDS AND SOME NEW ALKALOIDS

The kinetics of 14C incorporation into the alkaloidal fraction of two varieties of Conium maculatum (10-12- weeks old) were followed for periods of 0-7 days after 1-hr photosynthesis in an atmosphere of 14CO2. The specific activity time curves, their crossover points, and specific activity to pool ratios were consistent with the biosynthetic sequence: CO2 → → γ-coniceine → coniine → N-methylconiine. Minimum calculated rates of synthesis for γ-coniceine and coniine were about 4 mμmole/hr per g of fresh plant for Leetes’ Minnesota variety and 35 mμmole/hr per g for our California variety. The oxygenated bases conhydrine and pseudoconhydrine were not synthesized at a detectable rate, though similar as yet unidentified compounds were. A rapidly labeled compound, accounting for 95% of the 14C in the alkaloidal fraction and turning over completely in 1-2 days was detected in both varieties of Conium as well as in Sedum sarmentosum and Punica granatum, strongly suggesting it may be an intermediate prior to γ-coniceine. No trace was found of the reported precursors, cadaverine, or Δ1-piperideine, or of valerolactam or 3-ketoindolizidine. © 1969, American Chemical Society. All rights reserved.