Biogenesis of nicotine.

Radioactive nicotine was synthesized by Nicotiana rustica L. which was fed sodium acetate-1-C(14), sodium acetate-2-C(14), sodium pyruvate-1-C(14), or sodium pyruvate-3-C(14). Acetate-2-C(14) and pyruvate-3-C(14) were converted to nicotine with the least dilution of radioisotope, whereas pyruvate-1-C(14) was incorporated with a relatively large dilution. When acetate-1-C(14) was administered to the plants the nicotine contained C(14) only in the pyrrolidine ring. After acetate-2-C(14) was fed, C(14) was located in both the pyrrolidine and pyridine rings.