Riau University stated that the scales of Sunda pangolin (Manis javanica) are containing the active substance named Tramadol HCl which is a particle binder of psychotropic substances contained in the type of methamphetamine. Tramadol HCl is also an active substance contained in one of the analgesic drug used to treat severe pain either acute or chronic and postoperative pain.
http://bukitlawang.asia/...ficked-mammal-pangolin/

Abstract
RATIONALE:
Polydrug abuse is a common phenomenon in human drug addicts. Previous studies have shown that both tramadol (TRAM) and methamphetamine (METH) share the ability to modulate brain monoaminergic (dopamine, 5-hydroxytryptamine, and noradrenaline) systems that may be involved in behavioral sensitization to METH. Therefore, we hypothesized that there would be an interaction between TRAM and METH on behavioral sensitization induced by METH.
OBJECTIVES:
To investigate whether TRAM affects METH-induced behavioral sensitization.
METHODS:
Male Kunming mice were subjected to two regimens of drugs: (1) Mice were injected with TRAM (1-16 mg/kg, i.p.) alone or a combination of TRAM and METH (1 mg/kg, i.p.) once daily for 7 days. After 7 drug-free days (on day 15), animals were challenged with the corresponding TRAM dose or METH (1 mg/kg, i.p.). On days 1, 7, and 15, locomotion was monitored in the open field test after the last injection. (2) Mice received METH (1 mg/kg, i.p.) once daily for 7 days, followed by 7 drug-free days. On day 15, a challenge of TRAM (1-16 mg/kg, i.p.) or TRAM plus METH (1 mg/kg, i.p.) was given and then locomotor activity was quantified.
RESULTS:
TRAM or METH challenge did not induce hyperlocomotion in mice chronically treated with TRAM, and TRAM challenge was insufficient to induce subsequent hyperlocomotion in METH-sensitized mice. However, TRAM significantly increased METH-induced hyperlocomotion. TRAM plus METH-sensitized mice showed a significantly greater hyperlocomotor response to METH challenge than METH-sensitized mice. Furthermore, TRAM (16 mg/kg, i.p.) plus METH (1 mg/kg, i.p.) challenge enhanced the sensitized locomotor response compared to METH-alone (1 mg/kg, i.p.) challenge in METH-sensitized mice.
CONCLUSIONS:
TRAM fails to produce behavioral sensitization, and there is no apparent cross-sensitization between TRAM and METH. However, TRAM can increase METH-induced hyperlocomotion and potentiate the development and expression of behavioral sensitization to METH.
otentiating effect of tramadol on methamphetamine-induced behavioral sensitization in mice.

I seriously doubt that pangolins naturally produce tramadol in their scales. This may be a case of environmental contamination if pangolins come into contact with the urine of tramadol users. Maybe the poor creatures are attracted to tramadol-tainted urine

Last year I mentioned a paper that described the well-known drug tramadol as a natural product, isolated from a species of tree in Cameroon. Rather high concentrations were found in the root bark, and the evidence looked solid that the compound was indeed being made biochemically.
Well, thanks to chem-blogger Quintus (and a mention on Twitter by See Arr Oh), I’ve learned that this story has taken a very surprising turn. This new paper in Ang. Chem. investigates the situation more closely. And you can indeed extract tramadol from the stated species – there’s no doubt about it. You can extract three of its major metabolites, too – its three major mammalian metabolites. That’s because, as it turns out, tramadol is given extensively to cattle (!) in the region, so much of it that the parent drug and its metabolites have soaked into the soil enough for the African peach/pincushion tree to have taken it up into its roots.I didn’t see that one coming
http://blogs.sciencemag....tural_product_after_all

That's exactly the reference I was thinking of. Thanks for digging it up!

Next we'll find that pangolins love eating some part of the pincushion tree or live among its roots...

I'm still curious as to why extraction of tramadol from pangolin scales is preferred to synthesis of the compound...

Because - assuming you can get hold of a ready supply of pangolins - it's easier?