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: speciogynine is a naturally occurring monoterpene indole alkaloid in Mitragyna speciosa leaf. It has the same molecular formula and atom-to-atom connectivity as mitragynine but a different three-dimensional arrangement. That stereochemical difference changes how the molecule fits receptors, enzymes and proteins. For the wider chemical context, see Kiody’s kratom leaf alkaloids evidence map.
Speciogynine has been measured in authentic leaves and many commercial whole-leaf samples. Laboratory studies report serotonin-receptor binding, weak or assay-dependent opioid-receptor signaling and moderate inhibition of selected drug-metabolizing enzymes. A six-participant human study measured speciogynine after one characterized leaf preparation, but no controlled human trial has established what purified speciogynine does clinically. Receptor activity in cells or behavior in rodents is not evidence that speciogynine—or kratom leaf—treats pain, mood disorders, substance use or any other condition.
Speciogynine is one constituent, not another name for kratom
Kratom is the leaf of Mitragyna speciosa (Korth.) Havil., the accepted botanical name in Kew’s Plants of the World Online. The leaf contains many indole and oxindole alkaloids. Mitragynine is usually the most abundant measured alkaloid, while speciogynine, paynantheine and speciociliatine are frequently among the more prominent minor constituents.
“Minor” is relative. It means less abundant than the dominant constituent in a given sample; it does not mean inactive, harmless or unimportant. Nor is there one fixed speciogynine percentage for every tree, harvest or product. Genetics, leaf development, season, growing conditions, post-harvest processing and analytical method can all affect a result.
| Material | What it can answer | What it cannot establish alone |
|---|---|---|
| Authenticated leaf | Whether and how much speciogynine was measured in a defined plant sample | A universal concentration for all leaf |
| Commercial powder or tea | The profile of the submitted product and lot | Every package, vendor or preparation |
| Broad-spectrum extract | Which compounds were transferred or concentrated by a specified process | Equivalence to an equal mass of leaf |
| Purified speciogynine | Compound-specific receptor, enzyme, metabolism or animal findings | The combined effect of botanical leaf |
| Human plasma or urine | Exposure to speciogynine and its metabolites under defined conditions | Which compound produced a reported effect |
| Concentrated 7-OH or another derivative | A separate formulation with different composition and pharmacology | Anything specific about ordinary speciogynine-containing leaf |
How much speciogynine is in kratom leaf?
No single number describes natural leaf. A 2022 study led by Preston Manwill used high-performance liquid chromatography and multivariate analysis to compare authenticated plants and products. In one U.S.-grown “Rifat” plant set, speciogynine was unusually prominent, ranging from approximately 7.9 to 11.6 milligrams per gram in the sampled material. That finding demonstrates a possible chemotype; it is not a specification for all kratom and should not be transferred to a different cultivar or retail lot. Read Manwill et al., 2022.
A 2025 University of Florida experiment studied two cultivated varieties across two seasons and defined combinations of withering time and drying temperature. In the “Hawaii” cultivar, a particular low-temperature, short-withering treatment increased measured speciogynine relative to the comparison condition. The pattern did not justify a universal processing rule: cultivar, season and handling interacted, and only two varieties were tested. The authors reported no commercial financial conflict; one disclosed an editorial-board role. Read Zhang et al., 2025.
These studies explain why a lot-specific laboratory result is stronger evidence than an internet “typical percentage.” The unit and denominator also matter. Percent of dry leaf, milligrams per gram of finished product and percent of a total-alkaloid fraction are different quantities. Kiody’s kratom alkaloid-results guide explains how to compare them.
What a large U.S. product study found
Sharma and colleagues analyzed 341 product samples supplied by 330 participants from a 357-person, 15-day observational study. Most were described as whole-leaf products rather than extracts. Across ten quantified alkaloids, the samples were generally similar and closely matched the expected chromatographic–mass-spectrometry fingerprint of Mitragyna speciosa leaf. Speciogynine was part of that multi-alkaloid assessment.
This is supportive evidence that many sampled U.S. whole-leaf products shared a recognizable botanical pattern. It does not prove that every market product is authentic, consistent or uncontaminated; participants supplied products they were already using, and the sample was not a random market census. The study was NIH/NIDA-supported. Kirsten Smith disclosed paid advisory work for two botanical organizations, Smith and Christopher McCurdy disclosed expert-witness work involving kratom, and Erin Berthold disclosed a natural-products consulting company. Read Sharma et al., 2025.
Chemistry: speciogynine is a diastereomer of mitragynine
Speciogynine and mitragynine have the same molecular formula and the same sequence of bonded atoms. They differ in spatial configuration at one stereochemical center. Chemists call molecules with that relationship diastereomers. Kiody’s mitragynine guide explains the dominant leaf alkaloid separately.
A three-dimensional change can alter the orientation of functional groups when the molecule approaches a receptor or enzyme. It can also affect solubility, protein binding, membrane partitioning, distribution and clearance. Two diastereomers can therefore share a mass-spectrometry transition while behaving differently in chromatography and biology.
This is not merely a naming detail. A laboratory method that cannot chromatographically separate speciogynine from mitragynine or other related isomers can misidentify or misquantify them. In a biological sample, overlapping metabolites add another layer of difficulty.
How laboratories distinguish speciogynine
Targeted liquid chromatography–tandem mass spectrometry is commonly used to measure speciogynine in leaf, extracts and biological specimens. Sharma and colleagues published a 2019 UPLC–MS/MS method for ten kratom alkaloids, including speciogynine. The method used chromatographic separation to resolve diastereomers and compounds sharing ion transitions, followed by validation for accuracy, precision, robustness and stability. It was applied to alkaloid-rich fractions, ethanolic extracts, lyophilized teas and commercial products. The authors declared no conflicts. Read Sharma et al., 2019.
A defensible certificate of analysis should identify the sample, lot, method, result, unit, reporting basis and applicable detection or quantification limit. “Total alkaloids” does not reveal speciogynine unless the report defines which compounds were included. “Not detected” means below a stated method boundary in that sample, not absolute chemical zero. Kiody’s full-panel kratom COA guide provides a broader laboratory-document checklist.
Early opioid-receptor studies did not agree on a simple label
In 2016, Kruegel and colleagues synthesized and tested several Mitragyna alkaloids in human opioid-receptor systems. Speciogynine showed no measurable agonist response in the functional assay reported there. That result is one reason it should not be described as a smaller copy of mitragynine. Read Kruegel et al., 2016.
A later study by Gutridge and colleagues used cAMP inhibition and beta-arrestin-2 recruitment at mu-, delta- and kappa-opioid receptors. In that platform, purified speciogynine inhibited cAMP production with relatively low potency and did not measurably recruit beta-arrestin-2. The same paper included mouse experiments, but those animal results cannot establish a human effect or justify a product claim. Two authors disclosed that they co-founded Sparian Biosciences, a company developing opioid-related compounds. Read Gutridge et al., 2020.
A March 17, 2026 study again profiled purified kratom alkaloids using radioligand binding, cAMP, beta-arrestin-2 and GTP-gamma-S assays at human opioid receptors. Speciogynine produced assay-dependent binding and signaling results and again lacked measurable beta-arrestin-2 activity in the reported platform. High Point University and NIH centers supported the work; the authors declared no commercial financial relationships, and one author disclosed a journal editorial-board role. Read Hemby et al., 2026.
These differences are not necessarily contradictions caused by error. Functional readouts can change with receptor density, cell background, probe ligand, incubation time, signaling pathway and reference agonist. “Inactive,” “weak agonist” and “biased ligand” are meaningful only when the assay is named.
Serotonin-receptor findings are more prominent
León and colleagues tested purified kratom alkaloids at serotonin receptors in cells and then conducted behavioral experiments in rats. Speciogynine and paynantheine bound with relatively high affinity to human 5-HT1A and 5-HT2B receptors, unlike mitragynine in that assay set. Binding is not the same as activating a receptor.
The parent alkaloids did not activate 5-HT2B in the functional assay. In rats, speciogynine produced lower-lip retraction and antinociceptive responses that were blocked by a selective 5-HT1A antagonist rather than by an opioid antagonist. Follow-up cell tests indicated that the 5-HT1A agonist-like activity may have come from 9-O-desmethylspeciogynine, a metabolite, rather than from the parent compound. The metabolite also did not activate 5-HT2B in that experiment.
This is valuable mechanistic evidence, but it remains preclinical. Receptor binding, a rat behavioral proxy and antinociception do not demonstrate mood improvement, pain relief or psychiatric benefit in people. NIH agencies funded the study, and the authors declared no competing financial interest. Read León et al., 2021.
| Study | Material and system | Main finding | Boundary |
|---|---|---|---|
| Kruegel et al., 2016 | Purified compounds; human opioid-receptor cell assays | No measurable speciogynine agonism in the reported functional assay | One platform cannot define every signaling pathway |
| Gutridge et al., 2020 | Purified compounds; opioid-receptor assays and mice | Low-potency cAMP signaling without measurable beta-arrestin-2 recruitment | Preclinical; company-founder conflict disclosed |
| León et al., 2021 | Purified compounds and metabolites; serotonin assays and rats | 5-HT1A/5-HT2B binding; metabolite-dependent 5-HT1A functional hypothesis | No human administration or clinical outcome |
| Hemby et al., 2026 | Purified compounds; multiple human opioid-receptor readouts | Assay-dependent activity with no measurable beta-arrestin-2 recruitment | Cell signaling does not predict whole-leaf safety or benefit |
Why “beta-arrestin-free” does not mean safe
The absence of measurable beta-arrestin-2 recruitment in one assay is a mechanistic observation, not a safety certificate. A compound can produce effects through G proteins, metabolites, non-opioid receptors or pathways not measured in the experiment. Low potency can also become relevant if exposure is high enough, but cell concentrations do not translate directly into a serving or human effect.
Researchers continue to debate how much signaling bias, intrinsic efficacy and receptor reserve contribute to the adverse effects of opioid ligands. No speciogynine study has established a universal human safety threshold. Whole-leaf outcomes also reflect mitragynine, other alkaloids, contaminants, medications, alcohol and individual physiology.
Metabolism: the parent compound does not remain unchanged
Philipp and colleagues administered purified speciogynine to rats, identified nine phase-I and eight phase-II metabolites in rat urine, and then looked for corresponding compounds in human urine collected after kratom use. They identified three phase-I and five phase-II metabolites in the human samples. Improved liquid-chromatographic separation was required to distinguish speciogynine and its metabolites from mitragynine-related diastereomers.
The human urine samples documented metabolism after use of a multi-alkaloid preparation; they were not a controlled administration of isolated speciogynine. The rat experiment used what the authors described as a rather high purified-compound exposure. Species, route and exposure differences prevent conversion into human guidance. Read Philipp et al., 2010.
León’s later serotonin study provides a functional reason to care about those metabolites: 9-O-desmethylspeciogynine showed 5-HT1A agonist activity in vitro when the parent compound did not. That does not prove the metabolite reaches a human receptor at an active concentration after botanical-leaf use. It identifies a testable pathway.
What the first human pharmacokinetic study measured
In 2022, Tanna and colleagues administered one well-characterized dried-leaf product prepared as tea to six healthy adults. They measured speciogynine along with mitragynine, paynantheine, mitraciliatine, speciociliatine and isopaynantheine in plasma and urine. Five participants completed the full urine collection.
Speciogynine grouped with mitragynine and paynantheine as a 3S-configured alkaloid. In noncompartmental comparisons, the 3S group reached observed peak concentrations earlier, had lower overall plasma exposure, a longer terminal phase and a larger apparent terminal distribution volume than the 3R group. The authors’ follow-up experiments suggested that metabolism, protein binding, blood-to-plasma partitioning and physicochemical distribution could help explain the stereochemical differences.
The study is the strongest direct human speciogynine pharmacokinetic evidence identified for this guide, but it is intentionally narrow: six healthy adults, one leaf lot, one tea preparation and one exposure. It was not designed to determine therapeutic effects, long-term safety, dependence risk or rare adverse outcomes. NIH/NCCIH funded the work, and the authors declared no conflicts. Read Tanna et al., 2022.
| Observation | Supported conclusion | Unsupported leap |
|---|---|---|
| Speciogynine appeared in plasma after characterized leaf tea | The compound was absorbed from that preparation | It caused any particular subjective effect |
| A terminal phase could be estimated | Concentrations declined over multiple phases in the sampled adults | A universal personal detection window |
| 3S and 3R alkaloids differed | Stereochemistry was associated with distinct pharmacokinetic patterns | One stereochemical group is categorically safer |
| Metabolites appeared in human urine after kratom use | People metabolize speciogynine through multiple pathways | The amount or effect of each metabolite in every user |
| Only one characterized product was administered | The results are traceable to a defined preparation | Equivalence across powders, capsules, extracts or enhanced products |
Enzyme inhibition: a laboratory signal, not a complete interaction map
Kamble and colleagues tested six purified kratom alkaloids in human liver microsomes against major cytochrome P450 enzymes. Speciogynine moderately inhibited CYP2D6 and CYP2C19 activity under the study conditions. Mitragynine and corynantheidine were the stronger CYP2D6 inhibitors in that experiment.
These results identify interaction potential, not a proven clinical interaction caused by speciogynine. A microsomal concentration does not equal the free concentration at a person’s liver after leaf use. Product composition, intestinal exposure, protein binding, repeated use, other alkaloids and the companion medicine’s therapeutic margin all matter. NIH/NIDA supported the study, and the authors declared no conflicts. Read Kamble et al., 2020.
The cautious practical conclusion is that whole-leaf kratom can contain multiple enzyme-active constituents, so an interaction cannot be predicted from speciogynine alone. People who use medications should discuss kratom with a qualified clinician or pharmacist. Kiody’s kratom interaction evidence guide separates cell studies from clinical findings.
Speciogynine is not concentrated 7-OH
Speciogynine, 7-hydroxymitragynine, mitragynine pseudoindoxyl, MGM-15 and MGM-16 are distinct molecules. Their names, abundance, receptor profiles and legal treatment should not be blended.
Ordinary leaf contains a variable multi-alkaloid mixture in which speciogynine may be measurable. A concentrated or manufactured 7-OH product deliberately changes the alkaloid balance and can create a very different exposure. A result from a purified 7-OH experiment says nothing specific about speciogynine. Kiody’s botanical leaf versus concentrated 7-OH guide explains the product boundary, while the 7-OH formation guide separates leaf measurement, post-harvest chemistry, metabolism and deliberate concentration.
Claim check: what the evidence supports
| Claim | Best available evidence | What it does not establish |
|---|---|---|
| “Speciogynine is just weak mitragynine.” | It is a mitragynine diastereomer with distinct receptor and pharmacokinetic findings. | One alkaloid can substitute for the other. |
| “All kratom leaf contains the same amount.” | Plant, seasonal, post-harvest and product studies show substantial variation. | A universal percentage or strain-based prediction. |
| “Speciogynine is inactive at opioid receptors.” | One assay found no measurable agonism, while other platforms detected low-potency or pathway-specific signaling. | A single permanent receptor label independent of assay design. |
| “Serotonin binding proves an antidepressant effect.” | Purified speciogynine binds selected serotonin receptors; metabolite-dependent activity appeared in cells and rat behaviors. | Clinical efficacy, a psychiatric indication or a human dose. |
| “No beta-arrestin signal means no adverse effects.” | Several assays found little or no beta-arrestin-2 recruitment. | Universal safety, absence of dependence, interactions or impairment. |
| “Speciogynine has been proven safe in people.” | A six-person leaf-tea study measured pharmacokinetics. | Long-term safety, rare risks or isolate safety. |
| “Speciogynine explains every effect of leaf.” | It is one absorbed, metabolized constituent in a multi-alkaloid 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 speciogynine or for the amount of speciogynine 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.
Research gaps that matter next
- Independent surveys of authenticated fresh and dried leaves across more genotypes, climates, seasons and plant ages.
- Matched studies following speciogynine from living leaf through withering, drying, storage and common preparation methods.
- Interlaboratory validation using shared reference materials and methods that resolve diastereomers.
- Larger controlled human pharmacokinetic studies using multiple fully characterized botanical-leaf lots.
- Direct human measurement of 9-O-desmethylspeciogynine and other metabolites with validated stability controls.
- Standardized receptor studies that compare the same cell background, receptor density, reference agonist and signaling readouts.
- Clinical interaction research capable of separating speciogynine from the combined effects of mitragynine and other leaf alkaloids.
- Long-term observational work with verified product chemistry, frequency, co-use and health data.
Frequently asked questions
Is speciogynine naturally present in kratom leaf?
Yes. It has been identified and quantified in authenticated Mitragyna speciosa leaf. Its concentration varies among plants, harvests and products, so a lot-specific measurement is more informative than a universal internet average.
Is speciogynine the same as mitragynine?
No. They have the same molecular formula and connectivity but differ in three-dimensional configuration, making them diastereomers. That difference affects chromatography, receptor behavior and human pharmacokinetics.
Is speciogynine an opioid?
Purified speciogynine interacts weakly or in an assay-dependent way with opioid receptors. Some assays detected no measurable agonism; others detected low-potency G-protein signaling. It should not be described as pharmacologically identical to mitragynine, 7-OH or classical opioids.
Does speciogynine affect serotonin receptors?
Cell studies found relatively high binding affinity at 5-HT1A and 5-HT2B receptors. Functional and rat experiments suggest that a metabolite may account for 5-HT1A agonist-like effects. This is preclinical evidence, not proof of a mood or pain benefit in people.
Has speciogynine been studied in humans?
Yes, but narrowly. A six-participant study measured speciogynine in plasma and urine after one characterized dried-leaf tea. Human urine studies have also identified metabolites after kratom use. Neither design tested purified speciogynine as a treatment.
Can speciogynine interact with medications?
Interaction potential cannot be ruled out. Purified speciogynine moderately inhibited CYP2D6 and CYP2C19 in human liver microsomes. That laboratory signal does not predict every clinical combination, and whole leaf contains other enzyme-active alkaloids.
Can a COA distinguish speciogynine from mitragynine?
Yes, if the method has adequate chromatographic separation and appropriate reference standards. Because these compounds are diastereomers and can share mass transitions, an unexplained mass-spectrometry peak is not enough.
Is speciogynine the dangerous ingredient in kratom leaf?
The evidence does not support reducing leaf risk to one constituent. Speciogynine has measurable pharmacology, but mitragynine, other alkaloids, metabolites, interactions, contaminants, adulterants, product format and co-exposures also matter.
Primary evidence trail
- Philipp AA, et al. Phase I and II Metabolites of Speciogynine Identified in Rat and Human Urine. Journal of Mass Spectrometry. 2010. Purified-compound rat experiment plus human urine after kratom use; analytical metabolism evidence, not a clinical trial.
- Kruegel AC, et al. Synthetic and Receptor Signaling Explorations of the Mitragyna Alkaloids. Journal of the American Chemical Society. 2016. Purified compounds in human opioid-receptor assays; no human administration.
- Sharma A, et al. Simultaneous Quantification of Ten Key Kratom Alkaloids. Drug Testing and Analysis. 2019. Validated UPLC–MS/MS method applied to multiple kratom matrices; authors declared no conflicts.
- Gutridge AM, et al. G Protein-Biased Kratom Alkaloids and Synthetic Carfentanil-Amide Opioids. British Journal of Pharmacology. 2020. Opioid-receptor assays and mouse experiments; two authors disclosed founding an opioid-drug-development company.
- Kamble SH, et al. Cytochrome P450 Inhibition Mediated Drug-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. September 2021. Cell and rat studies of parent alkaloids and metabolites; NIH-funded; no competing financial interest declared.
- Tanna RS, et al. Clinical Pharmacokinetic Assessment of Kratom. Pharmaceutics. March 2022. Six healthy adults, 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 products; chemotype evidence, not a universal leaf 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 participant-supplied products; NIH-supported with disclosed advisory, expert-witness and consulting relationships.
- Zhang M, et al. Alkaloid Biosynthesis in Kratom Varies With Postharvest, Genetic and Seasonal Factors. Frontiers in Plant Science. 2025. Two cultivars and two seasons under controlled withering and drying conditions.
- 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 conflicts declared.
- National Institute on Drug Abuse. Kratom research overview. Official evidence summary reviewed September 15, 2026.
Editorial boundary: this guide explains evidence; it does not claim that kratom or speciogynine treats, cures or prevents a condition. It provides no dosing, lethal-dose or overdose 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.