There is no doubt precursor compounds which may vary from plant to plant or even time of collection.In the absence of a complete scientific assay of many samples, I would not discount an additional active component(s) with a variable structure and activity level in Mimosa.There are too many subjective differences to the experience between spice from Psychotria and spice from Mimosa. Psychotria produces a consistent product with consistent effects. With Mimosa it seems to be a bit different with each extract. Then there is the fact that Mimosa ,at least when fresh and cold water extracted is orally active. This would require another active agent to occur. With Mimosa there is more than just spice involved.