Mitragynine vs. 7-OH-Mitragynine: What Sets the Two Main Alkaloids Apart?
Anyone who takes a closer look at kratom will sooner or later encounter two names that keep coming up: mitragynine and 7-hydroxymitragynine – often abbreviated as 7-OH-MG. Both are alkaloids from the leaves of Mitragyna speciosa, both are being intensively researched, and both are chemically closely related – but not identical.
This article explains the differences in a factual way, without any claims about effects. The focus is exclusively on the chemistry and botany of these two compounds.
What is Mitragynine?
Mitragynine is the most abundant alkaloid by quantity in kratom leaves. Depending on origin, variety and processing, it can account for up to 66% of the total alkaloid content of a dried kratom leaf – some sources report even higher proportions.
Chemically, mitragynine belongs to the group of indole alkaloids and has a complex, multi-stage ring structure. Its molecular formula is C₂₃H₃₀N₂O₄ with a molecular weight of approximately 398.5 g/mol.
Mitragynine was first isolated from the kratom plant and structurally characterised as early as 1907. It is the compound most commonly cited as a reference value for commercial kratom products – for example as "225 mg mitragynine per bottle".
What is 7-Hydroxymitragynine?
7-Hydroxymitragynine (7-OH-MG) is, structurally speaking, an oxidation product of mitragynine – meaning it differs from mitragynine by an additional hydroxyl group (–OH) at position 7 of the molecule.
Its molecular formula is C₂₃H₃₀N₂O₅, with a molecular weight of approximately 414.5 g/mol – just one oxygen group more than mitragynine.
Although 7-OH-MG occurs in the natural kratom leaf in very small quantities – typically well below 1% of total alkaloid content – it has received considerable attention in the scientific literature. The reason: compared to mitragynine, it shows significantly higher affinity to certain receptors in laboratory studies.
How Does 7-OH-Mitragynine Form?
1. Biosynthetically within the plant: Mitragyna speciosa produces small amounts of 7-OH-MG directly in the leaves during normal plant metabolism – likely as a natural breakdown product of mitragynine through enzymatic oxidation.
2. Through oxidative degradation after harvest: After drying and storage, mitragynine can be converted to some degree into 7-OH-MG – particularly with heat, light and oxygen exposure. This is one reason why storage and processing of kratom products have quality relevance.
In kratom extracts, 7-OH-MG can be selectively concentrated, which explains why extracts frequently show different alkaloid profiles compared to raw powder.
The Chemical Difference at a Glance
| Property | Mitragynine | 7-OH-Mitragynine |
|---|---|---|
| Molecular formula | C₂₃H₃₀N₂O₄ | C₂₃H₃₀N₂O₅ |
| Molecular weight | ~398.5 g/mol | ~414.5 g/mol |
| Share in leaf | up to ~66% | below 1% |
| Origin | Primary alkaloid | Oxidation product / biosynthetic |
| First isolated | 1907 | 1994 |
Receptor Profile – What the Research Shows
Both alkaloids are described in pharmacology as partially selective agonists at the μ-opioid receptor (MOR). We have explained what this means in detail in our separate article on receptors.
In brief: higher affinity means that a compound can bind the receptor "better" or at lower concentrations. 7-OH-MG shows significantly higher affinity at the MOR in in-vitro studies than mitragynine – despite being far rarer in the leaf.
This is also why particular care regarding dosage accuracy is warranted in the development of 7-OH-mitragynine tablets or highly concentrated extracts.
Conclusion
Mitragynine and 7-OH-mitragynine are chemically closely related, but not identical. The main difference lies in a single hydroxyl group – which however has significant implications for receptor kinetics. Mitragynine dominates the alkaloid profile of the kratom plant by quantity; 7-OH-MG is the rarer but scientifically intensively discussed oxidation product.
Anyone buying kratom products should look for a complete COA that reports both values – because only then can the actual alkaloid composition of a product be properly assessed.
Legal Notice: This article is for informational purposes only and does not constitute legal advice. The content is not intended to encourage consumption. Laws may change; the applicable regulations and information from official authorities shall prevail. Image source: https://www.kratoein.com/