Tramadol Is Contaminant, Not Natural Product

A study confirms that the opiate tramadol recently found in trees is not a natural product, as controversially suggested in the past, but is instead human contamination (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201508646). Chemists were surprised by the discovery of tramadol, which is a synthetic compound, in Sarcocephalus latifolius, a tree native to Cameroon and neighboring countries. The results suggested that tramadol might be a newly discovered natural product and added to the list of opiates produced by plants (Angew. Chem. Int. Ed. 2013, DOI: 10.1002/anie.201305697). However, Michael Spiteller of the Technical University of Dortmund and colleagues argued that farmers, who feed tramadol to cattle to help them tolerate extreme heat, released the compound into the environment (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201406639). Now, Spiteller’s team reports the final nail in the coffin: The tramadol molecules from environmental samples contain no ¹⁴C. The abundance of ¹⁴C and other isotopes in molecules produced by living plants should match that of Earth’s atmosphere. The complete absence of ¹⁴C proves that the molecules are synthetic, the authors say.