What Is Pseudoindoxyl? Mitragynine Pseudoindoxyl, the Compound Behind the New Jersey Listing, and Why It Is Not a Leaf Alkaloid

Mitragynine pseudoindoxyl is a molecule nobody has shown the kratom plant to make. The products that carry it are made in a laboratory by rearranging one of the leaf's own alkaloids, it binds the mu-opioid receptor far harder than mitragynine does, and since 26 August 2026 it has been a Schedule I controlled substance in the United States, with New Jersey following automatically on 25 September. This page is the chemistry, the potency figures with their assays attached, the numbers the DEA used to schedule it, the two related compounds scheduled with it, and what all of that means for a company that sells concentrated leaf extracts, which is us.

What the DEA says it is

The cleanest description is the regulator's own. The DEA's temporary scheduling order of 26 August 2026 says that, unlike the alkaloids that occur naturally in the plant, mitragynine pseudoindoxyl, MGM-15 and MGM-16 "are produced through synthetic modifications of purified mitragynine isolates" or of another purified kratom alkaloid. Its July notice of intent calls mitragynine pseudoindoxyl a chemical rearrangement product of one of the leaf's minor alkaloids.

So the family tree runs like this. The leaf makes mitragynine. A small fraction of mitragynine oxidizes, in the drying leaf and in the body, into a minor alkaloid. Rearrange that minor alkaloid's ring system and you get a spiro-pseudoindoxyl core, a different shape of molecule with a different name. The DEA notes that "The first mention of mitragynine pseudoindoxyl in scientific literature dates to 1974 when mitragynine pseudoindoxyl was isolated as a metabolite from bio transformed mitragynine." For fifty years it was a curiosity in a journal. Then, per the DEA, "The first confirmed appearance of mitragynine pseudoindoxyl in consumer products was reported in 2024."

CFSRE, a forensic laboratory that tracks new drugs in the United States, agrees on the classification. The CFSRE monograph, dated 7 November 2025, opens: "Mitragynine pseudoindoxyl is categorized as a semi-synthetic analogue of mitragynine, the primary psychoactive component in Mitragyna speciosa (Kratom)." It gives the formula, C23H30N2O5, a molecular weight of 414.5, and the appearance in which it reached the laboratory: "Pills and tablets".

Not in the leaf, but made in the body, and that is the complication

Here is the part that makes this compound harder to write about than a plain synthetic. In 2020, a group publishing in ACS Pharmacology and Translational Science, Kamble and colleagues, incubated the leaf's minor oxidation alkaloid in the blood plasma of five species. In mouse, rat and monkey plasma it was largely stable, and in dog plasma moderately so. In human plasma it was not: after two hours, 53.8 percent of it had converted to mitragynine pseudoindoxyl, against 1.7 to 4.3 percent in the other four species. The authors write that the conversion "is irreversible" and that, as far as they knew, rearrangements of this kind "have not been previously described to occur in mammalian plasma."

Two of their sentences belong on any honest page about this molecule. First: "mitragynine pseudoindoxyl biosynthesis has not even been reported in Mitragyna speciosa". No one has reported the plant making it. Second: "the absolute conversion rate" of the parent "to mitragynine pseudoindoxyl is unknown", and the reaction "may be catalyzed by a genetically polymorphic enzyme or enzymes, which would potentially lead to substantial variability in an individual's relative exposure". In plain words, the compound is not in the leaf, but some of it may form inside some people after they take leaf, and nobody has measured how much or in whom. Both halves are true, and vendors tend to quote whichever half suits the sale.

How potent, with the assay attached

Every potency number you will read about this compound is true in one assay and wrong in another, so here they are with their owners. The DEA's summary: "mitragynine pseudoindoxyl is about 100 times more potent than mitragynine at the MOR", the mu-opioid receptor, from preclinical data. Kamble and colleagues, summarizing earlier studies, cite two figures from two different assays: in a receptor activation assay, "119-fold greater than mitragynine"; in the guinea pig ileum, a tissue model, "20-fold more potent than morphine at inhibiting contractions and 100-fold more potent than mitragynine". Same compound, three numbers, three methods. "A hundred times stronger than kratom" is none of them.

The paper that first characterized the pharmacology, Varadi and colleagues in the Journal of Medicinal Chemistry in 2016, measured binding affinity at 0.8 nanomolar for the mu receptor, against 230 for mitragynine and 4.6 for morphine in the same table, and reported that in mice the compound was "1.5-fold more potent than morphine after intracerebroventricular administration" and "3-fold more potent following subcutaneous" dosing. The same paper found it "developed analgesic tolerance more slowly than morphine, showed limited physical dependence, respiratory depression, constipation", which is the sentence most easily misread as a safety claim. Read what follows it: those are mouse findings for a research compound at controlled doses, in a paper whose stated hope was "novel antinociceptive drug candidates". The authors were describing a possible future medicine, not a chewable tablet in a gas station, and at a higher dose the same paper recorded that the compound "transiently lowered the respiratory rate".

The DEA's read of the dependence question, ten years and a consumer market later, is the opposite of reassuring: "chronic twice-daily administration of mitragynine pseudoindoxyl in rodents induces signs of opioid physical dependence and withdrawal symptoms in morphine addiction rodent models as evidenced by increased diarrhea, jumping, and rearing frequency occurring when naloxone was administered or when treatment with this alkaloid was tapered."

MGM-15 and MGM-16, the other two

The same order scheduled two related compounds. MGM-15 is, like pseudoindoxyl, made in a laboratory from a purified kratom alkaloid, and MGM-16 is a fluorinated version of MGM-15. The order lists each by a chemical name as well as its nickname, and covers them whatever numbering convention a laboratory uses. The DEA says "MGM-15 and MGM-16 are about 50 and 240 times more potent than morphine in animal models, respectively." Those are animal figures, with the same caution as above.

The DEA dates MGM-15's arrival precisely: "The emergence of MGM-15 in commercially available products was in September 2025." Its toxicology figure is the starkest in the order: "From February through April 2026, DEA TOX detected MGM-15 in 17 overdose cases, 16 resulting from a fatal event." MGM-16 is different. The DEA found "no evidence" of it on the consumer market and scheduled it anyway, because leaving it out "would create a regulatory loophole that manufacturers are already poised to exploit."

One difference matters for anyone reading a certificate. The Department of Justice's trace-amount policy, covered below, is about pseudoindoxyl only. It says in terms that it does not apply to MGM-15 or MGM-16.

What the products looked like

A study the DEA cites looked at 51 products sold online. "Seventy-six percent (39 of 51) of these products were chewable tablets, 18 percent were liquids (9 of 51), and the remaining three were either dried ice cream cones with ice cream (two products) or a chocolate bar (one product)." Thirty-five "had an appealing flavor", from berry and watermelon to pink lemonade and vanilla bean. For pseudoindoxyl and MGM-15 tablets generally, the DEA says prices ran "from about $2-4 per tablet or $34.99 per pack", and the notice lists several brand names they were sold under.

Most of them were not pseudoindoxyl alone. The DEA reports that 71 percent combined it with another concentrated kratom alkaloid, while 24 percent contained mitragynine pseudoindoxyl only. The marketing, in the DEA's account, promised the kind of effects no product in this category should promise. And then the line that tells you the vendors knew what they were selling: "Notably, vendors acknowledge significant public health risks, advising users to monitor for "habit-forming behavior," "high euphoria," "dependence," "overdose," and "death"."

The word "kratom" on those packages is the reason this page exists. The DEA: "Analysis of marketed mitragynine pseudoindoxyl products revealed misleading marketing strategies with claims that the products are "kratom."" And: "The branding creates a false sense of safety for unknowing consumers who may equate the term "botanical" with lower risk." The United Nations Office on Drugs and Crime made the same point in an early warning notice on 29 August 2025, describing products that mislead "consumers who intend to use a "low-potency botanical supplement" but instead end up with an opioid-like NPS." A new psychoactive substance, in a leaf's clothing.

The numbers the DEA scheduled it on

A temporary scheduling order has to rest on a finding of "imminent hazard to public safety", and the figures underneath that finding are worth reading because they are smaller and stranger than the headlines. Forensic laboratories: "there have been 19 reports of mitragynine pseudoindoxyl in Arkansas (n = 15), New York (n = 1), Ohio (n = 1), and Wyoming (n = 2) (queried June 23, 2026)." Toxicology: "a CFSRE trend report identified mitragynine pseudoindoxyl in 103 toxicology specimens and 12 drug materials". And the most serious: "between February 2025-May 2026, mitragynine pseudoindoxyl has been identified in at least 56 overdose cases, of which 48 were fatal events."

Two cautions. The first is the DEA's: the forensic count may be low partly because laboratories lacked the reference standards to see these compounds and faced "other analytic challenges", and because "closely related compounds require specific method and instrumentation for accurate identification". CFSRE only "first identified" the compound in its own laboratory "in September 2025". The UN notice lists the same problem: "poor stability especially in biological samples and limitations of some standard methods such as GC-MS". A compound that standard methods struggle to resolve from its parent is, by definition, one that a standard certificate of analysis may not have been looking for. Hold that thought.

The second caution is ours. The order also cites kratom-wide figures, "1,690 exposure calls involving kratom" in the first seven months of 2025 and a rise of over 1,200 percent in poison center calls over a decade. Those count every kratom product in the country. They are not pseudoindoxyl numbers, and a reader who sees them beside the 56 cases can come away thinking the compound is behind all of them. It is not, and the DEA does not say it is.

What the order does, and what New Jersey added

The order adds three paragraphs to 21 CFR 1308.11 and is deliberately wide. Pseudoindoxyl is listed "including its isomers, esters, ethers, salts, and salts of isomers, esters, and ethers", and because "nomenclature of this substance is not internationally standardized, compounds of this structure, regardless of numerical designation of atomic positions are covered". There is no threshold, no natural-occurrence carve-out and no testing limit anywhere in the text. "Possession of any quantity of mitragynine pseudoindoxyl, MGM-15, or MGM-16 in a manner not authorized by the CSA on or after August 26, 2026 is unlawful". The order runs "for two years, with a possible extension of one year, pending completion of the regular (permanent) scheduling process", and "Temporary scheduling orders are not subject to judicial review."

The Department of Justice's announcement of the order added a sentence that matters to anyone who sells extracts: federal prosecutors "will exercise enforcement discretion when only incidental trace amounts of MGPI are confirmed in a product otherwise consistent with botanical kratom", while noting that this "does not create a legal exemption and does not change MGPI's status as a schedule I controlled substance." The same release explains why: "The published scientific literature has not established MGPI as a naturally occurring kratom alkaloid. However, scientific and analytical questions remain about whether MGPI may be reported at incidental trace levels in some botanical products as a result of processing, storage or analytical conditions." That is prosecutorial policy, not law, it is federal, and it "does not apply to MGM-15 or MGM-16, or products containing manufactured, concentrated, fortified or intentionally added MGPI."

New Jersey added nothing and subtracted nothing. Its Controlled Dangerous Substances Act makes a federally scheduled substance controlled in the state 30 days after the Federal Register order unless the Director of the Division of Consumer Affairs objects. He did not, and on 25 September 2026 the Attorney General announced that the three compounds "will be illegal to possess and sell in New Jersey", that "Natural kratom and other synthetic kratom-related compounds not scheduled will not be illegal in New Jersey as a result of this change", and that "Any individual or business found violating this ban could face criminal charges." The New Jersey release carries no trace-amount statement of any kind. Federal Schedule I already applies in every state; whether other states also add the compounds to their own schedules depends on each state's law.

What this means for an extract, and for ours

An extract concentrates the leaf's alkaloids. No source we have read shows extraction itself producing pseudoindoxyl; the DEA describes the compound as made "through synthetic modifications of purified mitragynine isolates", and we do not add it to anything. But the Department of Justice's own sentence, quoted above, leaves the question open for botanical products, and the only honest answer to an open question about a product is a certificate.

There is one more honest point, and it comes from the plasma study rather than from any regulator. If some fraction of the leaf's minor alkaloid converts to pseudoindoxyl in human blood, then a more concentrated extract delivers more of the parent and, in some people, more of the product. Nobody has measured that in a person; the authors say so. But it is the reason our piece on mitragynine toxicity refuses to treat potency as a free variable, and the reason this one does too.

How to tell what you are holding

The three scheduled compounds travel under their own names and one nickname. Look for "pseudoindoxyl", "pseudo" or "MGM-15" on the label, in the product name, or in the marketing; MGM-16 has not been found in products but is covered too. The DEA's product table lists items labeled with MGM-15 by name and milligram amount, and others sold as "Pseudo" blends in tablet and liquid shot form. If any of those words is on the package, it is being sold as a Schedule I substance, which is unlawful to possess anywhere in the United States and, since 25 September, under New Jersey law too. If the label lists only kratom, Mitragyna speciosa or mitragynine, that is the seller's claim, not proof, because the DEA found pseudoindoxyl products marketed "with claims that the products are "kratom."" Ask for a certificate for that lot whose panel names all three.

If you have been taking pseudoindoxyl tablets and this page is the first you have heard that they are now contraband, the numbers in the red box are the right next call, and the order's own case report is the reason: a man who moved from leaf powder to concentrated tablets to pseudoindoxyl, eventually taking it many times a day, who "attempted to reduce dose and frequency of use but was unsuccessful", and who presented "with a clinical opiate withdrawal scale score of 31 (categorized as severe)". That is not a reason to switch to a more concentrated leaf extract, ours included. It is a reason to talk to a clinician who can prescribe the medicines that work for opioid withdrawal, which leaf is not. If you find a figure on this page that its source no longer supports, tell us; it gets corrected with the date on it.

Disclaimer: this page summarizes publicly available material as of 28 September 2026 and links to primary sources so you can check them. Potency figures are quoted with the assay they come from and are preclinical. It is general information, not legal or medical advice, and no substitute for counsel in your jurisdiction or for a clinician. Statements about botanical products have not been evaluated by the Food and Drug Administration, and no product is intended to diagnose, treat, cure or prevent any disease.