Last year a French - Cameroonian - Swiss team reported they had isolated the compound tramadol (0.4% by weight) from the root bark of the Cameroonian medicinal plant Nauclea latifolia (Boumendjel et al. DOI). This is unexpected because tramadol was until then only known as a synthetic pain-killer as a simplified morphine derivative.
The finding was also somewhat expected because in Cameroon the root bark is used in traditional medicine in pain relief. With hindsight, the finding that the compound was isolated as a racemate just like synthetic tramadol should be a warning sign. On the other hand the researchers did make an effort to exclude the possibility of contamination by synthetic tramadol by isotope analysis.
Brand new research by a German - Cameroonian team now expresses serious doubt (Kusari et al. DOI). Their interest in the Boumendjel work was triggered by the isotope results and on re-examination with fresh samples they found: 1] much less tramadol (up to 0.0000017% by weight) in samples from one region and 2] no tramadol at all in samples from another region. Another finding explains it all: in the first region, local farmers were found to deploy synthetic tramadol as stamina enhancers for themselves and for their cattle when used as draft animals. In region number two this practice was unknown.
The team then went on to isolate tramadol from ground samples and water samples in general and were then confident to conclude that the tramadol found in the plant sample had originated from from synthetic tramadol passed through the urine of humans and cattle.
Note added: removed comment on enantiomeric composition