Search the word pseudoindoxyl and you land in a strange mix of chemistry abstracts, forensic laboratory bulletins, and product pages, rarely with anyone stopping to explain what the molecule actually is. This page is that explanation. Where mitragynine pseudoindoxyl comes from structurally, how it differs from mitragynine and 7-hydroxymitragynine, why it has a research paper trail stretching back to the 1990s, and what a laboratory has to do to tell it apart from its closest chemical relative on a certificate of analysis.

The short version: Mitragynine pseudoindoxyl (formula C23H30N2O5, about 414.5 daltons) is a rearranged form of the mitragynine skeleton. Mitragynine oxidizes at the indole ring to give 7-hydroxymitragynine, and that intermediate can rearrange into a spiro-linked pseudoindoxyl core. Because it is a rearrangement rather than an addition, pseudoindoxyl and 7-OH are isomers with identical molecular formulas, which is exactly why some analytical methods cannot separate them. As of July 30, 2026, mitragynine pseudoindoxyl is not federally scheduled in the United States, though DEA published a notice of intent on July 6, 2026 that could change that. Details and dates below.

What exactly is mitragynine pseudoindoxyl?

It is an indole alkaloid derivative built on the same carbon framework as mitragynine, the principal alkaloid of Mitragyna speciosa, but with the ring system rearranged. Its molecular formula is C23H30N2O5, with a molecular weight of roughly 414.5 daltons.

The defining structural feature is in the name. Mitragynine carries a conventional indole ring system. Pseudoindoxyl carries a pseudoindoxyl core, an indolin-3-one, joined to the rest of the molecule at a single shared carbon atom. That shared-carbon junction is what chemists call a spiro center, and it forces the two ring systems into perpendicular planes rather than the flat, fused arrangement of an indole. The Center for Forensic Science Research and Education gives the full systematic name as methyl (E)-2-(6-ethyl-4'-methoxy-3'-oxo-spiro[3,5,6,7,8,8a-hexahydro-2H-indolizine-1,2'-indoline]-7-yl)-3-methoxy-prop-2-enoate, which is a mouthful that mostly just spells out the spiro junction and the ester and methoxy groups hanging off it.

Worth stating plainly, because the search results muddle it: "pseudoindoxyl" is a description of a ring system in organic chemistry. It is not a plant, not a strain, and not a category of leaf material.

How does mitragynine turn into pseudoindoxyl?

Two steps, and the intermediate is the compound most people already know.

Step one is oxidation. Mitragynine (C23H30N2O4) picks up an oxygen at position 7 of the indole ring, producing 7-hydroxymitragynine. This happens in the body through hepatic enzyme activity, and it also happens in the bottle, since the indole position is chemically vulnerable to oxidation over time.

Step two is a skeletal rearrangement. The hydroxy-imine created in step one is unstable, and under acidic conditions the molecule reorganizes: a bond migrates, the ring system contracts and re-forms, and the result is the spiro pseudoindoxyl core. The published chemistry describes this as a 1,2-semipinacol or pinacol-type rearrangement, the same class of reaction taught in second-year organic chemistry.

The consequence of that mechanism matters more than the mechanism itself. A rearrangement shuffles atoms, it does not add or subtract them. So 7-hydroxymitragynine and mitragynine pseudoindoxyl end up with the same molecular formula and the same nominal mass. They are structural isomers of each other. Hold onto that, because it drives the entire analytical problem discussed further down.

In the laboratory, chemists first reached the compound through biomimetic semisynthesis from mitragynine, essentially running the same oxidation-then-rearrangement sequence in glassware. Those early routes were low yielding. More recent work has produced enantioselective total syntheses that build the molecule from simpler starting materials rather than starting from plant alkaloid.

Pseudoindoxyl versus mitragynine versus 7-OH: what changes?

Three compounds, three different skeletons, one shared ancestry.

  • Mitragynine. C23H30N2O4, about 398.5 daltons. Indole core. The dominant alkaloid in raw Mitragyna speciosa leaf.
  • 7-hydroxymitragynine (7-OH). C23H30N2O5, about 414.5 daltons. One oxygen heavier than mitragynine, built on an indolenine core. Present in leaf at trace levels and formed from mitragynine metabolically.
  • Mitragynine pseudoindoxyl. Same formula and mass as 7-OH, different skeleton. Spiro pseudoindoxyl core.

Natural occurrence is where sources genuinely diverge, so here is the honest read. Older pharmacology literature describes pseudoindoxyl as an oxidative rearrangement product of mitragynine and treats it as a minor constituent associated with the plant. The 2025 forensic monograph from the Center for Forensic Science Research and Education takes a narrower position, classifying the material appearing in consumer products as a semi-synthetic analogue of mitragynine and noting that it can also form as a metabolite by way of 7-OH. What both accounts agree on is that it is nowhere near a major component of raw leaf. If a finished product contains a meaningful quantity of it, that quantity did not come from simply grinding leaves.

Why does this compound keep appearing in research papers?

Because medicinal chemists found it structurally interesting a long time before the consumer market did.

A 1998 paper in Life Sciences compared the opioid receptor agonistic characteristics of mitragynine pseudoindoxyl against mitragynine, and reported that the rearranged compound bound opioid receptors far more tightly in their assays than the parent alkaloid did. Follow-up work by the same Japanese group, published in the Journal of Medicinal Chemistry in 2002, reported that the compound's effect in an animal model did not scale with those receptor numbers, which is a useful reminder that binding affinity measured in a dish is a laboratory measurement and not a prediction of anything else.

The compound resurfaced prominently in 2016, when Váradi, Majumdar and co-authors at Memorial Sloan Kettering Cancer Center published work in the Journal of Medicinal Chemistry characterizing mitragynine and corynantheidine pseudoindoxyls as mu-opioid receptor agonists and delta-opioid receptor antagonists that did not recruit β-arrestin-2 in their assays. That combination is why the scaffold drew attention from drug-discovery groups.

Everything in the preceding two paragraphs is preclinical laboratory research on an isolated compound, published for medicinal chemistry purposes. None of it describes a consumer product, and none of it should be read as a statement about what any product does for anyone.

Is mitragynine pseudoindoxyl legal right now?

As of July 30, 2026, mitragynine pseudoindoxyl is not a federally scheduled controlled substance in the United States. That status has an active federal proceeding attached to it, so the date on that sentence is doing real work.

On July 6, 2026, the Drug Enforcement Administration published a notice of intent in the Federal Register, docket DEA-1644, proposing to temporarily place mitragynine pseudoindoxyl, MGM-15 (dihydro-7-hydroxymitragynine) and MGM-16 (9-fluoro-7-hydroxymitragynine) into Schedule I of the Controlled Substances Act. A companion notice published the same day addresses 7-hydroxymitragynine above a specified threshold. Under the temporary scheduling procedure, DEA indicated an order could be published on or after August 5, 2026, would take effect on its publication date, and would remain in effect for two years, with a possible one-year extension if permanent scheduling proceedings are underway.

We are not going to forecast whether, when, or in what form that order issues. Read the docket yourself if you want the primary source. Separately, state and municipal law on kratom-derived alkaloids moves on its own schedule and does not wait for federal action, so a compound's federal status tells you only part of what applies where you live. We track current federal and state status on our regulation terminal, and any product page here reflects what is lawful to ship at the time you are reading it.

How do laboratories identify pseudoindoxyl on a COA?

This is where the isomer problem from earlier becomes practical. Since pseudoindoxyl and 7-OH share a molecular formula, they share a mass, and mass alone cannot tell an analyst which one is in the vial.

The Center for Forensic Science Research and Education has published on exactly this, reporting that the two compounds co-elute and are effectively indistinguishable under traditional gas chromatography mass spectrometry, and that liquid chromatography quadrupole time-of-flight mass spectrometry was required to identify and differentiate them. Their monograph lists a protonated molecular ion of 415.2227 for pseudoindoxyl. Separation depends on the chromatography, not on the mass detector alone. The same laboratory reported its first confirmed identification of mitragynine pseudoindoxyl in commercial products marketed as kratom alternatives in September 2025.

For anyone reading a certificate of analysis, that translates into four things to check:

  • The analyte is named. A line reading "total alkaloids" or "7-OH" without a stated method does not resolve the isomer question.
  • The method is stated. LC-MS/MS or LC-QTOF-MS can distinguish these compounds; a GC-MS-only result generally cannot.
  • The lot identifier on the COA matches the lot you are holding. An undated, unlinked PDF proves nothing about your unit.
  • The laboratory is named, so the result can be traced to an accountable party.

Every lot we sell has its COA posted at /pages/lab-results, matched to the lot, so those four checks can be run before anyone spends a dollar. Items we group by this alkaloid class sit in the pseudo collection, and availability there follows whatever the law permits at the time.

What is actually worth remembering

Pseudoindoxyl names a rearranged ring system, not a plant or a product line. It sits one skeletal rearrangement past 7-hydroxymitragynine and two chemical steps past mitragynine, and it carries the same molecular formula as 7-OH, which is why the analytical method used on a COA matters as much as the number printed on it.

Its legal status carries a date, and that date is July 30, 2026. Anything you read about this compound without a date attached, including this article a year from now, should be verified against the current Federal Register and your own state's statutes before you act on it.

This article is for informational purposes only. These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Products are intended for adults 21 years of age or older. Check your state and local laws before purchasing.