Taken from the
mitragynine wiki
"Research on mitragynine
structure–activity relationships have led to discovery of new potent opioid agonists, notably some C10-halogen and 2,3-ethylene glycol bridged
derivatives of 7-hydroxymitragynine. The most potent one is the 10-fluoro ethylene glycol adduct of 7-hydroxymitragynine with a potency 4-fold higher than 7-hydroxymitragynine. Other modification led to 2,3-dihydro derivatives such as MGM-15, prepared by reduction of 7-hydroxymitragynine with
sodium borohydride. The antinociceptive effect of MGM-15 is between 15 and 50 times more potent than that of morphine after subcutaneous and oral administration.
[13]"
interesting....
Anyways, CNS depression is not the only way to die from kratom overdose. "According to clinical reviews, a kratom overdose can cause
liver toxicity,
seizures,
coma, and death." I'd guess whatever is causing the liver toxicity is the culprit.
The mechanism won't change because of isolation, although it may with higher dosages. I don't think partial agonist become full though, as that is largely dependent upon the shape of the molecule and it's ability to bind to receptors. Full agonist are full agonist at low doses, as far as I'm aware. The part that would change would be in relation to enzymatic function, or lack of due to high doses. Or other parts of the body's chemistry that is changed due to the presence of the drug. The change due to body chemistry may not be a good/pleasureable one either.
On alkaloid extraction, from wiki:
"Because of the structural diversity of alkaloids, there is no single method of their extraction from natural raw materials.[175] Most methods exploit the property of most alkaloids to be soluble in organic solvents but not in water, and the opposite tendency of their salts.
Most plants contain several alkaloids. Their mixture is extracted first and then individual alkaloids are separated.
[176] Plants are thoroughly ground before extraction.
[175][177] Most alkaloids are present in the raw plants in the form of salts of organic acids.
[175] The extracted alkaloids may remain salts or change into bases.
[176] Base extraction is achieved by processing the raw material with alkaline solutions and extracting the alkaloid bases with organic solvents, such as 1,2-dichloroethane, chloroform, diethyl ether or benzene. Then, the impurities are dissolved by weak acids; this converts alkaloid bases into salts that are washed away with water. If necessary, an aqueous solution of alkaloid salts is again made alkaline and treated with an organic solvent. The process is repeated until the desired purity is achieved.
In the acidic extraction, the raw plant material is processed by a weak acidic solution (
e.g.,
acetic acid in water, ethanol, or methanol). A base is then added to convert alkaloids to basic forms that are extracted with organic solvent (if the extraction was performed with alcohol, it is removed first, and the remainder is dissolved in water). The solution is purified as described above.
[175][178]
Alkaloids are separated from their mixture using their different solubility in certain solvents and different reactivity with certain reagents or by
distillation"
According to the
mitragynine wiki page, it is an
indole alkaloid.
Looking at the indole alkaloid page shows "Depending on their biosynthesis, two types of indole alkaloids are distinguished; isoprenoids and non-isoprenoids" followed by a list of both.
Looking back at the mitragynine page, it shows "It is structurally related to
yohimbine but shows a totally different pharmacology", which is one of the chemicals listed under isoprenoid.
I'm am getting over my head here, but I believe that to be the info needed. Based on the info on these two wiki pages, and largely the fact that people commonly report making "kratom tea" with success, it seems mytragynine is water soluble. If a high level of purity isn't the end goal, one could potentially forego all the above info and just make a tea and reduce it via evaporation.
EDIT: Obviously more info would help here, but I am reaching the limits of my chemistry understanding. It might be possible to do an alkaloid extraction like that described in the wiki article, but it would have to be modified to account for mitragynine being soluable in water.