Last reviewed September 15, 2026. Educational content for adults 21+. This article is not medical advice and does not recommend a dose or use. Kiody does not sell concentrated 7-hydroxymitragynine (7-OH) products.
The short answer: paynantheine is a naturally occurring monoterpene indole alkaloid found in Mitragyna speciosa leaf. It is one part of the broader kratom leaf alkaloid profile and is structurally related to mitragynine but contains a carbon–carbon double bond where mitragynine has an ethyl group. That small chemical difference changes the molecule’s shape, mass, metabolism and behavior in experimental systems.
Paynantheine has been measured in authenticated plants, leaf powders, teas, extracts and human biological samples after kratom use. The strongest direct human evidence is pharmacokinetic: researchers measured how paynantheine appeared and declined in plasma after six healthy adults received one characterized dried-leaf tea. Laboratory and animal studies suggest opioid- and serotonin-receptor activity, but those findings do not establish a clinical effect, medical use or safety profile for purified paynantheine—or for botanical kratom leaf.
Paynantheine is part of kratom leaf, not a synonym for kratom
Kratom refers to the leaf of Mitragyna speciosa (Korth.) Havil., the accepted botanical name recorded by Kew’s Plants of the World Online. The leaf is a multi-constituent botanical matrix. Mitragynine is commonly the most abundant quantified alkaloid, while paynantheine, speciogynine and speciociliatine are often among the more prominent secondary alkaloids.
A result for purified paynantheine answers a compound-level question. It does not reproduce the balance of constituents in leaf, and it cannot show how the complete botanical mixture behaves in a person. Conversely, a whole-leaf observation cannot identify paynantheine as the cause of an effect unless the study was designed to isolate that relationship.
| Material or system | Question it can address | What it cannot establish alone |
|---|---|---|
| Authenticated fresh or dried leaf | Whether paynantheine occurs in a defined plant sample and at what measured level | A universal concentration for every tree, harvest or product |
| Commercial whole-leaf powder | The alkaloid fingerprint of the submitted lot | Consistency across all packages or vendors |
| Tea or other preparation | What transferred into that preparation under defined conditions | Equivalence to the starting powder or another preparation |
| Broad-spectrum extract | Composition after a specified extraction process | Equal exposure from the same mass of ordinary leaf |
| Purified paynantheine | Compound-specific chemistry, receptor, enzyme, metabolism or animal findings | The combined activity of botanical leaf |
| Human plasma or urine | Absorption, disposition or metabolite detection under defined conditions | Which constituent caused a subjective or clinical outcome |
| Concentrated 7-OH or another derivative | The properties of a chemically different product category | Anything specific about ordinary paynantheine-containing leaf |
How abundant is paynantheine?
There is no scientifically defensible percentage that applies to every natural leaf. Plant genetics, leaf maturity, geography, season, cultivation, post-harvest handling and analytical method can all change a measurement. The denominator matters too: percent of dry leaf, percent of a finished product, milligrams per gram and percent of an isolated total-alkaloid fraction are not interchangeable.
A validated 2019 UPLC–MS/MS study measured ten alkaloids across alkaloid-rich fractions, ethanolic extracts, lyophilized teas and commercial products. In that deliberately mixed set of matrices, paynantheine ranged from 0.3% to 12.8% by weight. The high end should not be presented as a normal leaf value because concentrated fractions and extracts were included. The study’s real lesson is that material identity must accompany every number. The method was validated for accuracy, precision, robustness and stability, and the authors declared no conflicts. Read Sharma et al., 2019.
A 2022 analysis of authenticated plants and retail materials likewise found that paynantheine and other major alkaloids varied across samples and chemotypes. The design was valuable for distinguishing botanical patterns, but it was not a random census of the worldwide crop or U.S. market. Read Manwill et al., 2022.
The most useful consumer-facing question is therefore not “What is the universal paynantheine percentage?” It is “What did a suitable method measure in this identified lot, in which unit, and relative to what denominator?” Kiody’s guide to reading kratom alkaloid results explains those distinctions.
What a large U.S. whole-leaf study adds
Sharma and colleagues published an analysis of 341 participant-supplied product samples from 330 people enrolled in a 357-person ecological momentary assessment. Most samples were described as whole-leaf products rather than extracts. The researchers quantified ten alkaloids, including paynantheine, and reported that the sampled products were broadly similar to one another and closely matched the expected chromatographic–mass-spectrometry fingerprint of Mitragyna speciosa leaf.
That is meaningful supportive evidence for the recognizable chemistry of many sampled U.S. whole-leaf products. It does not prove that every retail lot is authentic, accurately labeled, uncontaminated or chemically equivalent. Participants supplied products they were already using; this was not a randomized market-surveillance program. Read Sharma et al., 2025.
The research was supported by the NIH National Institute on Drug Abuse. Kirsten Smith disclosed paid scientific-advisory work for two botanical organizations; Smith and Christopher McCurdy disclosed expert-witness work in kratom cases; and Erin Berthold disclosed a natural-products consulting company. Disclosures do not invalidate a study, but readers should consider them alongside sampling, methods and reproducibility.
Chemistry: a vinyl analog with a stereochemical partner
NIH’s PubChem record lists paynantheine as C23H28N2O4. Mitragynine is C23H30N2O4. The two-hydrogen difference reflects a carbon–carbon double bond in paynantheine’s vinyl substituent. For that reason, researchers describe paynantheine as a dehydro or vinyl analog of mitragynine. View the NIH PubChem record.
Paynantheine also has a stereochemical relative called isopaynantheine. They share the same molecular formula and atom-to-atom connectivity but differ in three-dimensional configuration, making them diastereomers. The six-person pharmacokinetic study classified paynantheine with the 3S group and isopaynantheine with the 3R group. Their different plasma profiles demonstrate that three-dimensional arrangement can matter even when molecular mass and many mass-spectrometry fragments match.
This distinction is central to good analysis. A laboratory that reports only an ion transition without demonstrating chromatographic separation may combine, confuse or misassign related compounds. A label that says “paynantheine” is not proof that isopaynantheine, metabolites or co-eluting peaks were excluded.
How laboratories identify and quantify paynantheine
Targeted liquid chromatography coupled to tandem mass spectrometry is a common approach. The chromatography separates compounds in time; the mass spectrometer then measures selected ions and fragments. For paynantheine, sufficient chromatographic resolution is essential because isopaynantheine can share mass transitions and because biological samples contain related metabolites.
The 2019 ten-alkaloid method used a C18 column and a 22.5-minute gradient to resolve diastereomers and compounds with common ion transitions. A 2026 University of Florida-led method expanded the human-plasma panel to 12 parent alkaloids—including paynantheine and isopaynantheine—plus five mitragynine-related metabolites. The method was validated over a reported 1–250 ng/mL plasma range and applied to samples from four regular kratom users in a clinical study. This was an analytical-method paper, not proof that paynantheine produced any clinical effect. Read Kanumuri et al., 2026.
A useful certificate of analysis should identify the sample and lot, matrix, preparation, extraction procedure, method, reference standard, result, unit and reporting limits. “Total alkaloids” is not a paynantheine result unless the report defines which compounds were included and how each was measured. “Not detected” means below a stated method boundary in that sample; it does not mean absolute chemical absence. Kiody’s full-panel COA checklist explains what to look for.
Opioid-receptor findings depend on the assay
Gutridge and colleagues tested purified paynantheine, speciogynine, mitragynine, 7-OH and two alkaloid extracts. In cells expressing mouse mu-, delta- or kappa-opioid receptors, paynantheine inhibited cAMP production at all three receptors but was much less potent than standard reference agonists. In separate human-receptor cell lines, it did not produce measurable beta-arrestin-2 recruitment under the reported conditions. Read Gutridge et al., 2020.
The same paper injected purified paynantheine into mice and observed reduced voluntary alcohol intake without a statistically significant locomotor change at the lowest effective exposure tested. That is an animal behavioral finding, not evidence that paynantheine treats alcohol use disorder in people. The route bypassed ordinary oral consumption, and the study was not designed to establish human safety or efficacy. Two authors disclosed that they co-founded Sparian Biosciences, a company developing opioid-related compounds.
A March 17, 2026 investigation profiled a wider panel of purified kratom alkaloids across human opioid-receptor binding and signaling assays. Paynantheine produced measurable activity in some mu- and/or kappa-receptor readouts, while the magnitude and classification depended on the assay. The study again found no simple basis for treating all kratom alkaloids as pharmacologically identical. University and NIH centers supported the work; the authors reported no commercial financial relationships, and one disclosed a journal editorial-board role. Read Hemby et al., 2026.
These findings justify the careful phrase “assay-dependent opioid-receptor activity.” They do not justify calling paynantheine a proven human opioid medicine, a harmless antagonist or an equivalent of 7-OH. Cell background, receptor species, receptor density, reference agonist, incubation time and measured signaling pathway can all alter the apparent result.
| Study | Tested material and model | Finding | Evidence boundary |
|---|---|---|---|
| Gutridge et al., 2020 | Purified paynantheine; opioid-receptor cell systems and injected mice | Low-potency cAMP signaling, no measurable beta-arrestin-2 recruitment, and altered alcohol intake in mice | Different receptor species across assays; animal behavior is not clinical efficacy |
| León et al., 2021 | Purified parent alkaloids and metabolites; serotonin-receptor assays and rats | High-affinity 5-HT1A/5-HT2B binding with a metabolite-dependent 5-HT1A explanation | No human administration of purified paynantheine |
| Tanna et al., 2022 | One characterized dried-leaf tea; six healthy adults | Paynantheine was absorbed and showed a 3S-type plasma profile | Pharmacokinetics, not proof of compound-specific effects |
| Hemby et al., 2026 | Purified alkaloids; multiple human opioid-receptor assays | Measurable, assay-dependent mu- and/or kappa-receptor activity | Cell signaling cannot establish whole-leaf benefit or safety |
Serotonin evidence may be more distinctive than the opioid label
León and colleagues compared several purified kratom alkaloids at serotonin receptors. At 100 nanomolar, paynantheine displaced about 69% of a 5-HT1A radioligand and about 54% of a 5-HT2B radioligand in the reported binding screens. Those results indicate binding affinity; binding alone does not show whether a compound activates, blocks or otherwise changes receptor signaling.
In functional assays, the parent paynantheine molecule did not activate human 5-HT1A or 5-HT2B receptors under the tested conditions. Yet injected paynantheine produced a rat behavioral response associated with 5-HT1A activation, and a selective 5-HT1A antagonist reduced that response. The researchers investigated the mismatch and found that 9-O-desmethylpaynantheine—also called gambireine in the paper—acted as a 5-HT1A agonist in cells. The metabolite behaved as an inverse partial agonist rather than an agonist at 5-HT2B in that platform. Read León et al., 2021.
This is a coherent metabolism-first hypothesis: the parent compound binds, while a metabolite may carry more of the observed functional activity. It remains preclinical. The study did not establish the concentration of that metabolite at human receptors after ordinary leaf use, demonstrate a therapeutic effect, or define long-term cardiovascular risk. NIH agencies funded the work, and the authors declared no competing financial interest.
Why a “no beta-arrestin” result is not a safety claim
Beta-arrestin-2 is one signaling route used in opioid-receptor research. Failure to detect its recruitment in a particular cell assay says only that the experiment did not measure that signal under those conditions. Paynantheine can still signal through G proteins, be transformed into active metabolites, bind non-opioid receptors or affect targets not included in the panel.
It is also inappropriate to infer respiratory safety from paynantheine’s weaker cell potency. No controlled human respiratory study of purified paynantheine was identified for this guide. A result involving isolated mitragynine, 7-OH, a synthetic analog or a mixed extract cannot be assigned to paynantheine. Whole-leaf risk also depends on other constituents, product chemistry, co-exposures and the individual.
Metabolism: paynantheine becomes a family of compounds
Philipp and colleagues isolated paynantheine from kratom leaf, administered the purified compound to rats and used liquid chromatography with low- and high-resolution ion-trap mass spectrometry to map its metabolites. They identified nine phase-I products, including O-demethylated, carboxylated and reduced forms. Several metabolites were also present as glucuronide or sulfate conjugates. Read Philipp et al., 2010.
The investigators then compared those patterns with urine from people who had used kratom preparations. Paynantheine-related compounds helped explain dehydro analogs previously observed in human urine. This did not constitute a controlled human administration of isolated paynantheine: the human donors used multi-alkaloid kratom, and the purified-compound experiment was conducted in rats. The research supports metabolite identification, not a universal human elimination timeline.
A 2011 follow-up studied isopaynantheine, paynantheine’s low-abundance diastereomer. Its rat pathways were broadly comparable to those of paynantheine, while fewer metabolites could be detected in human urine because isopaynantheine was present at much lower amounts. The study also showed why chromatographic separation is required to distinguish parent diastereomers and their overlapping metabolite families. Read Philipp et al., 2011.
What the six-person human pharmacokinetic study actually showed
Tanna and colleagues administered one characterized Indonesian dried-leaf product prepared as tea to six healthy adults. The product’s paynantheine content was about 30% of its mitragynine content. Researchers collected plasma over multiple days and urine from five participants who completed the full collection. They measured paynantheine, isopaynantheine and four other parent alkaloids rather than treating kratom as a single chemical. Read Tanna et al., 2022.
Paynantheine grouped with mitragynine and speciogynine as a 3S-configured alkaloid. Compared as groups, the 3S compounds reached their observed plasma peaks earlier, had lower overall exposure, longer terminal phases and larger apparent terminal distribution volumes than the 3R compounds mitraciliatine, speciociliatine and isopaynantheine. Follow-up laboratory work suggested metabolism, protein binding, blood-to-plasma partitioning and physicochemical distribution may contribute to those differences.
For paynantheine specifically, a lower amount in the starting product did not translate proportionally into a tiny plasma signal; the authors reported trends in peak concentration and overall exposure resembling those of the more abundant mitragynine. That observation is a reminder that leaf abundance is only one determinant of systemic exposure.
The study’s limits are substantial and transparent: six healthy adults, one product, one preparation, one administration and no purified-paynantheine comparison arm. It did not measure long-term use, rare events, dependence, clinical efficacy or every possible product format. NIH/NCCIH supported the work, and the authors declared no conflicts of interest.
| Observation | Reasonable conclusion | Conclusion the study cannot support |
|---|---|---|
| Paynantheine appeared in plasma after leaf tea | It was absorbed from that characterized preparation | It caused any particular reported sensation |
| Paynantheine and isopaynantheine had different profiles | Stereochemistry affects disposition | One diastereomer is categorically safe or beneficial |
| A terminal phase was measured | Concentrations declined over more than one kinetic phase | A universal personal detection window |
| One defined lot was used | Exposure can be tied to known product chemistry | Equivalence across leaf powders, capsules, extracts and enhanced products |
| Six adults participated | The study provides direct preliminary human pharmacokinetics | Population-wide safety, rare-risk incidence or clinical effectiveness |
Enzyme inhibition: a signal that still needs clinical translation
Kamble and colleagues incubated six purified kratom alkaloids with human liver microsomes and enzyme-selective probe substrates. Paynantheine showed moderate inhibition of CYP2D6 activity under the study conditions. Mitragynine and corynantheidine were the more potent CYP2D6 inhibitors in the same experiment. NIH/NIDA supported the research, and the authors declared no conflicts. Read Kamble et al., 2020.
A microsomal inhibition result is not a confirmed medication interaction in a person. Clinical importance depends on free concentrations at the enzyme site, absorption, protein binding, repeated exposure, intestinal metabolism, other leaf constituents and the companion medicine’s therapeutic margin. Whole leaf contains several compounds that can affect drug-metabolizing systems, so paynantheine cannot be evaluated in isolation when predicting a product-level interaction.
The responsible takeaway is uncertainty, not reassurance or alarm. People who take medication should disclose kratom use to a qualified clinician or pharmacist, especially when a medicine has a narrow therapeutic range. Kiody’s kratom interactions guide separates human interaction studies from cell and microsomal signals.
Paynantheine is not 7-OH, pseudoindoxyl or a synthetic derivative
For the separate chemistry of trace leaf measurements, post-harvest formation and human metabolism, see Kiody’s 7-hydroxymitragynine formation guide.
Paynantheine, 7-hydroxymitragynine, mitragynine pseudoindoxyl, MGM-15 and MGM-16 are different molecules. They must not be grouped merely because their names appear in kratom discussions or because some interact with opioid receptors.
Ordinary botanical leaf is a variable multi-alkaloid material in which paynantheine commonly appears alongside mitragynine and other constituents. Concentrated or manufactured 7-OH products deliberately alter that balance. Mitragynine pseudoindoxyl and the MGM compounds have separate structures and current federal treatment. Results from those derivatives cannot establish paynantheine’s potency, safety or legal status. Kiody’s botanical leaf versus concentrated 7-OH guide provides a format-level comparison.
Claim check: paynantheine statements that need correction
| Claim | Best available evidence | What remains unproven |
|---|---|---|
| “Paynantheine is just a weaker form of mitragynine.” | It is a vinyl analog with different mass, metabolites, receptor findings and human disposition. | That either compound can substitute for the other. |
| “Every leaf contains the same percentage.” | Authenticated-plant and product studies show variable multi-alkaloid profiles. | A universal value or reliable prediction from a color or variety name. |
| “It is definitely an opioid agonist.” | Some cell assays detected low-potency opioid signaling; results depend on receptor and readout. | A single assay-independent label or a defined human opioid effect. |
| “Serotonin binding proves a mood benefit.” | Paynantheine binds selected serotonin receptors, and a metabolite activated 5-HT1A in cells. | Antidepressant, anti-anxiety, analgesic or other clinical efficacy. |
| “No beta-arrestin signal means no respiratory risk.” | Several assays reported no measurable beta-arrestin-2 recruitment. | Respiratory safety, absence of impairment or protection against interactions. |
| “Human trials prove paynantheine is safe.” | A six-person study measured pharmacokinetics after one leaf preparation. | Long-term safety, rare-event risk or isolate safety. |
| “Paynantheine is concentrated 7-OH.” | They are chemically and analytically distinct compounds. | Transfer of 7-OH findings or rules to paynantheine. |
| “Paynantheine explains the effects of kratom leaf.” | It is one absorbed and metabolized constituent within a complex matrix. | Causation for any individual effect or outcome. |
Why animal findings cannot be converted into human guidance
Purified-compound animal experiments can help identify metabolism, receptor pathways and hypotheses for later study. They do not establish a validated human threshold for purified paynantheine or for the amount of paynantheine within ordinary botanical leaf.
Direct conversion would ignore species, administration route, absorption, metabolism, product chemistry and the multi-alkaloid leaf matrix. This guide therefore reports study design and evidence boundaries without turning preclinical exposures into serving advice.
The research questions that should come next
- Independent mapping of paynantheine across authenticated genotypes, locations, seasons, leaf ages and harvest practices.
- Matched studies following the same leaves through withering, drying, storage and common preparation methods.
- Interlaboratory comparison using certified reference materials and chromatography that resolves paynantheine from isopaynantheine.
- Larger human pharmacokinetic studies with several fully characterized botanical-leaf lots and prespecified sex, age and metabolic analyses.
- Validated human measurement of 9-O-desmethylpaynantheine and other paynantheine metabolites after ordinary leaf preparations.
- Standardized receptor experiments that use the same species, cell background, receptor density, reference compounds and signaling endpoints.
- Clinical interaction research capable of separating paynantheine’s contribution from mitragynine and the rest of the leaf matrix.
- Longitudinal observational studies pairing verified product chemistry with frequency, co-use, medications and health outcomes.
Frequently asked questions
Is paynantheine naturally present in kratom leaf?
Yes. Researchers have isolated it from Mitragyna speciosa leaf and quantified it in authenticated plants, whole-leaf products, teas and extracts. Its level varies, so a lot-specific result is more informative than a universal average.
Is paynantheine the same chemical as mitragynine?
No. Paynantheine is a vinyl or dehydro analog of mitragynine and has two fewer hydrogen atoms. The molecules are related but analytically, metabolically and pharmacologically distinct.
What is isopaynantheine?
Isopaynantheine is a diastereomer of paynantheine: the two compounds have the same formula and connectivity but different three-dimensional configuration. They can share mass transitions, so adequate chromatographic separation is important.
Does paynantheine activate opioid receptors?
Some cell systems detected relatively low-potency G-protein signaling at opioid receptors, while the apparent activity varied by receptor and assay. No measurable beta-arrestin-2 recruitment appeared in the 2020 platform. These are laboratory findings, not a defined human effect.
Does paynantheine interact with serotonin receptors?
It bound with relatively high affinity to 5-HT1A and 5-HT2B receptors in a 2021 study. The parent compound did not activate the canonical pathways tested, while its 9-O-desmethyl metabolite activated 5-HT1A in cells. Human clinical relevance is not established.
Has paynantheine been measured in people?
Yes. A six-participant study measured it in plasma and urine after one characterized dried-leaf tea. Older human urine work also identified paynantheine-related metabolites after kratom use. Neither study administered purified paynantheine as a treatment.
Could paynantheine interact with medication?
It moderately inhibited CYP2D6 in human liver microsomes. That identifies interaction potential but does not predict a clinical outcome. Whole leaf also contains other enzyme-active constituents, so medication questions should be discussed with a clinician or pharmacist.
Is paynantheine the only constituent that matters for leaf risk?
No. Available evidence does not support assigning botanical-leaf risk to paynantheine alone. Product format, total alkaloid profile, metabolites, individual susceptibility, medications, other substances, adulterants and contaminants can all matter.
Primary evidence trail
- Philipp AA, et al. Use of LC–Mass Spectrometry for Studying the Metabolism of Paynantheine in Rat and Human Urine. Analytical and Bioanalytical Chemistry. 2010. Purified-paynantheine rat metabolism plus comparison with human urine after kratom use; not a controlled human isolate study.
- Philipp AA, et al. Metabolism of Mitraciliatine and Isopaynantheine in Rat and Human Urine. Journal of Chromatography B. 2011. Diastereomer and metabolite-separation evidence; purified compounds were administered to rats, not people.
- Sharma A, et al. Simultaneous Quantification of Ten Key Kratom Alkaloids. Drug Testing and Analysis. 2019. Validated UPLC–MS/MS across multiple matrices; mixed products and extracts do not define ordinary-leaf ranges.
- Gutridge AM, et al. G Protein-Biased Kratom Alkaloids and Synthetic Carfentanil-Amide Opioids. British Journal of Pharmacology. 2020. Purified compounds in receptor assays and mice; company-founder interests disclosed.
- Kamble SH, et al. Cytochrome P450 Inhibition-Mediated Interaction Potential of Kratom Alkaloids. Toxicology Letters. 2020. Purified alkaloids in human liver microsomes; NIH/NIDA-funded; no conflicts declared.
- León F, et al. Activity of Kratom Alkaloids at Serotonin Receptors. Journal of Medicinal Chemistry. 2021. Binding and functional cell assays plus rat experiments; NIH-funded; no competing financial interest declared.
- Tanna RS, et al. Clinical Pharmacokinetic Assessment of Kratom. Pharmaceutics. March 2022. Six healthy adults and one characterized dried-leaf tea; NIH/NCCIH-funded; no conflicts declared.
- Manwill PK, et al. Kratom Validation: Quantitative Analysis Reveals Chemotypes of Plants and Products. Planta Medica. 2022. Authenticated plants and retail products; composition evidence, not a universal specification.
- Sharma A, et al. Chemical Analysis and Alkaloid Intake for Kratom Products Available in the United States. Drug Testing and Analysis. 2025. Ten-alkaloid analysis of 341 primarily whole-leaf samples; NIH-supported with advisory, expert-witness and consulting disclosures.
- Hemby SE, et al. Multifaceted Modulation of Human Opioid Receptors by Kratom Alkaloids. Frontiers in Pharmacology. March 17, 2026. Purified alkaloids across multiple human-receptor assays; university and NIH support; no commercial financial relationships declared.
- Kanumuri SRR, et al. Simultaneous Quantification of Seventeen Kratom Alkaloids and Metabolites in Human Plasma. Pharmaceutical Biology. 2026. Validated 12-parent-alkaloid plus five-metabolite plasma method applied to four regular users; analytical evidence, not an effects trial.
- National Institute on Drug Abuse. Kratom research overview. Official background and evidence-gap summary reviewed September 15, 2026.
Editorial boundary: this guide explains evidence; it does not claim that kratom or paynantheine treats, cures or prevents a condition. It provides no dosing or animal-to-human conversion instructions. If you take medication, have a health condition, are pregnant or breastfeeding, or experience concerning symptoms, consult a qualified health professional. Do not drive or operate heavy machinery while impaired.