Failure of 3-hydroxy-3-phenylpropanoic acid and cinnamic acid to serve as precursors of tropic acid in Datura innoxia

Datura innoxia plants were fed the R- and S-isomers of 3-¹⁴C]-3-hydroxy-3-phenylpropanoic acid, and 3-¹⁴C]cinnamic acid along with dl-4-³H]phenylalanine. The hyoscyamine and scopolamine isolated from the plants 7 days later were labeled with tritium, but devoid of ¹⁴C, indicating that 3-hydroxy-3-phenylpropanoic acid and cinnamic acid are not intermediates between phenylalanine and tropic acid. The ³H] tropic acid obtained by hydrolysis of the hyoscyamine was degraded and shown to have essentially all its tritium located at the para position of its phenyl group, a result consistent with previous work.