Biosynthesis of Radioactive Nicotine

Abstract

Randomly labeled radioactive nicotine, free of nornicotine, was prepared by biosynthesis. Nicotiana rustica was used because it has a very high nicotine-nornicotine ratio. Young, actively-growing plants were placed in cylindrical Pyrex jars 2 ft. tall and 12 in. in diam. The top was covered with a circular glass plate and sealed with caulking compound. Inlets for the introduction of C14O2 and nutrient soln. were provided. Temp. was maintained between 65[degree]-75[degree]F; 300-foot candles of illumination was provided by white fluorescent lights. After 4-6 weeks plants were harvested, and the nicotine was extracted and purified by procedures described in the text. The purity of the radioactive nicotine was proved by spectrophoto-metric absorption curves, by its precipitation and solubility properties, by mixed melting point detns. and by biological tests. Pure unlabeled nicotine was used as standard. The high-est rate of nicotine formation occurs during early growth period. The radioactivity in the nicotine was roughly proportional to the amt. of C14O2 taken up by the growing plants. The highest activity of radioactive nicotine was 501,000 c.p.m./mg. (0.3503 uc./mg.).