The 7-acetoxy derivative of mitragynine is commercially available, but, although it is per-weight unit, more potent than mitragynine and.or 7-OH mitragynine itself, it does seem subjectively less satisfying, having done a bioassay on both materials, there seems to be something 'missing', I can't quantify it in words, but subjectively, it does not feel as good.
For both pain (I have a broken-off shard of bone floating around in my knee joint from a childhood fight and an accident) and for relaxation, I definately find that out of mitragynine, the hydroxylated, and the acetoxy derivative, the hydroxy substitution was preferable.
The full spectrum alkaloid extract rather than the pure compound though is more effective by far in my opinion, theres quite the mix of different indole alkaloids in Mitragyna Speciosa, mitragynine derivatives being responsible for the mu receptor agonism (I think its a partial agonist btw), there are adrenoreceptor ligands that act like yohimbine, but these comprise a fairly small quantity of the total alkaloidal profile, and, most interestingly, in kratom (M.Speciosa) that has been improperly stored/aged, a compound called mitragynine pseudoxindole forms, which is a delta selective agonist, which I am inclined to think, would boost the effective antinociceptive action of kratom quite some, as delta opioid receptors are involved in mediation of pain at the spinal level.
Not, mind you, that I have done a side-by-side comparison of old, mangy kratom and fresh stuff, although once I get enough money to afford some plants, I intend to do exactly that