Guide to 40+ Kratom Alkaloids: Chemistry & Concentrations

Last Updated: April 2026

Kratom (Mitragyna speciosa) contains at least 54 identified alkaloids. Mitragynine is the most abundant, making up as much as 66% of total alkaloid content in some varieties, while dozens of other alkaloids are present in much smaller amounts. These compounds fall into two main structural categories: indole alkaloids (such as mitragynine) and oxindole alkaloids (such as mitraphylline). This guide is a composition reference: it describes what each alkaloid is, its chemical family, and its typical concentration in the plant.

I've spent 5 years studying kratom alkaloids because understanding them changed how I approach this plant entirely. When I first started working with kratom in 2021, I thought strain names told the whole story. They don't. The alkaloid profile does. After helping over 10,000 customers since 1999, we've learned that understanding even the basics of kratom chemistry helps people make more informed choices about which products suit their preferences.

This guide covers all 40+ major kratom alkaloids, their concentrations, and their chemical characteristics. I'll focus on what's actually practical and useful rather than just listing chemical formulas.

How Many Alkaloids Are in Kratom?

Scientists have identified at least 54 distinct alkaloids in kratom leaves, though most research focuses on fewer than 10. According to research published in ACS Chemical Neuroscience, these alkaloids fall into two main structural categories: indole alkaloids and oxindole alkaloids.

The number matters because kratom's character doesn't come from a single compound. Mitragynine alone doesn't explain why different batches feel different, or why the same strain from different vendors can produce noticeably different experiences. The interplay between dozens of alkaloids creates what researchers call the "entourage effect," where compounds are thought to work together.

Why Alkaloid Counts Vary

You'll see different numbers reported, from "over 40" to "54 or more." This variation comes from several factors:

• Detection methods improve over time: Better analytical equipment finds compounds previously missed
• Some alkaloids exist in trace amounts: Below detection thresholds in many samples
• Metabolites vs. native alkaloids: Some compounds form during processing or metabolism
• Regional and seasonal variation: Not all alkaloids appear in all samples

The practical takeaway: kratom contains dozens of distinct compounds, not just one or two. This complexity is why standardizing kratom products remains challenging and why batch-to-batch variation exists even within the same vendor.

The Two Main Categories: Indole vs. Oxindole Alkaloids

All kratom alkaloids belong to one of two structural families. Understanding this distinction helps make sense of the long list of compounds.

Indole Alkaloids

Indole alkaloids are the primary compounds in kratom and are the main contributors to the character users notice. They're defined by a specific chemical ring structure (the indole ring) that allows them to interact with several receptor systems.

Key indole alkaloids include:

• Mitragynine (most abundant, up to 66% of total alkaloids)
• 7-hydroxymitragynine
• Speciociliatine
• Speciogynine
• Paynantheine
• Mitraciliatine
• Corynantheidine
• Ajmalicine

Chemical family: Indole alkaloids are the primary structural class of compounds in kratom. Customers commonly describe indole-rich material as more energizing at lower amounts and more relaxing at higher amounts, as a subjective experience.

Oxindole Alkaloids

Oxindole alkaloids have a modified chemical structure with an additional oxygen atom. They are present in kratom in low amounts.

Key oxindole alkaloids include:

• Mitraphylline
• Speciofoline
• Corynoxine A and B
• Rhynchophylline
• Isorhynchophylline
• Isomitraphylline

Research context: Many oxindole alkaloids are also found in other plants and have been the subject of general pharmacology research. In kratom they occur in low amounts and are not considered primary contributors to the experience most users notice.

Quick Comparison

The 5 Major Alkaloids (Most Abundant)

These five alkaloids make up the vast majority of kratom's total alkaloid content. Understanding them gives you a solid foundation for understanding any kratom product.

1. Mitragynine (40-66% of Total Alkaloids)

Mitragynine is the star of the show. It's the most abundant alkaloid in kratom, typically comprising 1-2% of dry leaf weight and up to 66% of total alkaloid content in Thai varieties (though Malaysian varieties may contain only about 12%).

Concentration: 0.7-38.7% w/w in commercial products

Other pharmacology studied (laboratory research):

• Binds to alpha-1 and alpha-2 adrenergic receptors
• Binds to serotonin 5-HT1A and 5-HT2A receptors
• Binds to dopamine D1 receptors

What customers describe:

• A more energizing, brisk character at lower amounts
• A more relaxed, settled character at higher amounts
• An uplifted mood, as a subjective experience

Research note: Mitragynine is the most-studied kratom alkaloid and remains an active area of ongoing scientific research.

2. Paynantheine (3-12.8% of Total Alkaloids)

Paynantheine is the second most abundant alkaloid in most kratom samples. It's an indole alkaloid structurally related to mitragynine but with different chemical properties.

Concentration: 0.3-12.8% w/w in commercial products

Other pharmacology studied (laboratory research):

• Studied for smooth muscle relaxation
• Possible adrenergic activity

Research status: Less studied than mitragynine, but its high concentration suggests it plays a role in kratom's overall composition. Some researchers believe it modulates or extends the activity of other alkaloids.

3. Speciociliatine (3-12.3% of Total Alkaloids)

Speciociliatine is a diastereoisomer of mitragynine, meaning it has the same chemical formula but a different three-dimensional structure. This structural difference changes how it interacts with receptors.

Concentration: 0.4-12.3% w/w in commercial products

Chemistry note: Speciociliatine is a diastereoisomer of mitragynine, sharing its chemical formula but differing in three-dimensional structure.

Research status: Findings in the literature vary, which highlights the need for more standardized research on this minor alkaloid.

4. Speciogynine (2-5.3% of Total Alkaloids)

Speciogynine is another diastereoisomer of mitragynine and typically the fourth most abundant alkaloid in kratom.

Concentration: 0.1-5.3% w/w in commercial products

Other pharmacology studied (laboratory research):

• Significant binding at alpha-2A, 2B, and 2C adrenergic receptors

Research note: Speciogynine's strong adrenergic binding is often discussed in connection with the more energizing, focused character customers describe at lower amounts.

5. 7-Hydroxymitragynine (<0.05-2% of Total Alkaloids)

7-hydroxymitragynine (often called "7-OH") is a minor alkaloid that occurs in very low amounts in the natural leaf. It forms through oxidation of mitragynine during the drying process and also appears as a metabolite of mitragynine in the body.

Concentration: Typically <0.05% in fresh leaves; can be higher in processed products and extracts

Chemistry note (laboratory research):

• Shorter half-life than mitragynine (roughly 2-3 hours vs. 23-24 hours)
• Forms through oxidation of mitragynine and also appears as a metabolite

Regulatory note: As of August 2026, concentrated 7-hydroxymitragynine (7-OH) products above federal thresholds are being placed under DEA Schedule I; this article does not promote 7-OH products. Flavourz focuses on traditional whole-leaf kratom rather than concentrated 7-OH extracts.

The Big 5 Summary Table

Secondary Alkaloids (1-2% Each)

These alkaloids typically comprise less than 2% of total alkaloid content individually but collectively contribute to kratom's overall composition.

Corynantheidine

Concentration: <1% typically

Notes: Also found in yohimbe. It has been the subject of general pharmacology research published in Frontiers in Pharmacology.

Mitraciliatine

Concentration: <1% typically

Notes: A diastereoisomer of mitragynine. May contribute to kratom's distinctive alkaloid profile.

Isopaynantheine

Concentration: Variable, typically <1%

Notes: A diastereoisomer of paynantheine. Research into its chemistry is ongoing.

Corynoxine A and Corynoxine B

Concentration: 0.01-2.8% combined

Notes: These oxindole alkaloids contribute to kratom's overall composition.

Isocorynantheidine

Concentration: Variable, typically <1%

Notes: Similar structure to corynantheidine. Contributes to kratom's overall alkaloid profile.

Minor Alkaloids (<1% Each)

These alkaloids exist in smaller concentrations and are largely under-researched. Many are also found in other plant species, and the notes below describe their chemical family and research status rather than any effect in kratom.

Oxindole Group (also found in related plants)

Additional Minor Alkaloids

Other Notable Minor Alkaloids

Complete Alkaloid Master List

For reference, here's a more complete listing of identified kratom alkaloids. Research status varies widely, from well-characterized (mitragynine) to barely studied (many trace compounds).

Note: This list represents major identified compounds. Additional trace alkaloids, N-oxides, and metabolites bring the total count above 54 in comprehensive analyses.

How Alkaloids Interact With Receptor Systems

Kratom's complexity comes from its alkaloids interacting with multiple receptor systems at once. Understanding these systems, as studied in the laboratory, helps explain why the plant's character varies with dose, strain, and individual.

Structural Chemistry

Kratom's alkaloids fall into two structural families whose proportions differ from batch to batch:

• Indole alkaloids: The most abundant structural class, including mitragynine and 7-hydroxymitragynine.
• Oxindole alkaloids: Present in lower amounts, including mitraphylline and the corynoxines.
• Structural isomers: Many alkaloids are diastereoisomers that share a chemical formula but differ in three-dimensional shape.

Adrenergic Receptors

These receptors respond to adrenaline/noradrenaline and are involved in alertness. Research shows mitragynine and speciogynine bind to alpha-2A, 2B, and 2C adrenergic receptors. This binding is often discussed in connection with the more energizing character customers describe at lower amounts and why some strains feel more stimulating than others.

Serotonin Receptors

Mitragynine binds to 5-HT1A and 5-HT2A serotonin receptors. These receptors are involved in mood regulation. This binding is sometimes discussed in connection with the mood-related character some users report as a subjective experience.

Dopamine Receptors

Some kratom alkaloids interact with D1 and D2 dopamine receptors. Dopamine is involved in motivation and reward. This interaction is discussed in research on kratom's overall profile.

Other Systems

Alkaloids like rhynchophylline act as NMDA receptor antagonists and calcium channel modulators in laboratory studies. Ajmalicine and related compounds are studied in circulation research. These are minor components and are not the primary contributors to what users notice.

How Processing and Strain Affect Alkaloid Content

One question I hear constantly: "Do different strains actually have different alkaloids?" The answer is nuanced.

The Science of Strain Variation

Research published in Frontiers in Plant Science in 2025 showed that alkaloid content varies significantly based on:

• Cultivar (genetics): Different kratom tree varieties produce different baseline alkaloid profiles
• Harvest season: 7-hydroxymitragynine was detected only in specific seasons, varying by cultivar
• Postharvest processing: Withering and drying temperatures dramatically affect final alkaloid content
• Growing conditions: Shade vs. sun, soil composition, and humidity all influence alkaloid production

Processing Effects

The vein "color" of kratom (red, green, white) is primarily determined by processing, not the color of actual leaf veins:

Regional Variation

Thai kratom varieties typically contain up to 66% mitragynine, while Malaysian varieties may contain only about 12%. This dramatic difference comes from genetic variation between regional populations and different growing conditions, and users interested in how Thai genetics shape a specific red vein profile can learn from this detailed red kratom resource that covers Red Thai's character and dosing in depth.

Total alkaloid concentration in dried leaves ranges from 0.5% to 1.5% of leaf weight. This means a 5-gram serving contains roughly 25-75mg of total alkaloids, with mitragynine being the majority.

Practical Implications: What This Means for Users

Understanding alkaloids helps you make more informed decisions about kratom. Here's how to apply this knowledge:

Choosing Products

If a vendor provides alkaloid testing (mitragynine percentage), you can use this to compare products. Higher mitragynine doesn't automatically mean "better," but it indicates concentration. A product with 1.5% mitragynine will likely call for smaller servings than one with 0.7%.

Understanding Your Response

Individual response to kratom varies because people metabolize alkaloids differently. The enzyme CYP3A4 converts mitragynine to 7-hydroxymitragynine. People with higher CYP3A4 activity may experience a different response from the same serving.

Tolerance and Rotation

Different strains have different alkaloid ratios. Rotating between strains exposes your receptors to varying alkaloid profiles, which many customers prefer over using the same product daily.

Product Selection and Extracts

Products with elevated 7-hydroxymitragynine (above natural leaf levels) are concentrated extracts rather than traditional whole-leaf kratom. As of August 2026, concentrated 7-OH products above federal thresholds are being placed under DEA Schedule I. Many customers choose traditional whole-leaf kratom products rather than concentrated extracts. The UNODC has noted concerns about novel products with high 7-hydroxymitragynine concentrations appearing on markets.

Frequently Asked Questions

How many alkaloids are in kratom?

Scientists have identified at least 54 distinct alkaloids in kratom leaves, though the exact number continues to grow as detection methods improve. The majority of research focuses on fewer than 10 major alkaloids, with mitragynine and 7-hydroxymitragynine receiving the most attention.

What is the main alkaloid in kratom?

Mitragynine is the most abundant alkaloid, comprising 40-66% of total alkaloid content and 1-2% of dry leaf weight. In laboratory research it also binds to adrenergic and serotonin receptors.

What does mitragynine do?

In laboratory research, mitragynine binds to adrenergic and serotonin receptors. Customers describe a dose-dependent character: more energizing at smaller servings and more relaxing at larger servings.

What is the difference between mitragynine and 7-hydroxymitragynine?

7-hydroxymitragynine is a minor alkaloid present in much lower concentrations than mitragynine (typically less than 0.05% in fresh leaves versus 1-2% for mitragynine). It has a shorter half-life than mitragynine (2-3 hours versus 23-24 hours). Note that as of August 2026, concentrated 7-OH products above federal thresholds are being placed under DEA Schedule I.

What are indole and oxindole alkaloids?

Indole alkaloids (like mitragynine) have an indole ring structure and are the main contributors to kratom's character. Oxindole alkaloids (like mitraphylline) have a modified, oxygen-containing structure and occur in low amounts.

Do different strains have different alkaloids?

All kratom strains contain the same alkaloids, but the ratios and concentrations differ. These differences come from genetic variation between plant populations, growing conditions, harvest timing, and especially processing methods (fermentation, drying temperature and duration). Red, green, and white "strains" reflect processing differences more than genetic differences.

What alkaloids drive kratom's character?

Mitragynine and 7-hydroxymitragynine are the primary drivers of the character most users associate with kratom. Speciogynine and other alkaloids that bind adrenergic receptors are linked to a more stimulating character. Paynantheine is studied for smooth muscle relaxation. The overall experience results from the combined presence of many alkaloids.

How do kratom alkaloids interact in the body?

Kratom alkaloids interact with several receptor systems, including adrenergic receptors (alertness and energy), serotonin receptors (mood), and dopamine receptors (motivation and reward). This multi-receptor activity creates kratom's distinctive overall profile.

Final Thoughts

Kratom's 40+ alkaloids create a complex chemical profile that science is still working to understand. The key takeaways:

• Mitragynine dominates: It's the most abundant alkaloid and the primary studied compound
• 7-hydroxymitragynine is a minor component: It occurs in very low amounts in the natural leaf; concentrated 7-OH products are now subject to DEA scheduling (see above)
• Secondary alkaloids contribute: The "entourage effect" of multiple compounds shapes kratom's unique profile
• Processing matters: How kratom is dried and processed affects final alkaloid ratios significantly
• Individual variation exists: Your response depends on metabolism, genetics, and the specific product's alkaloid profile

Understanding alkaloids won't make you a chemist, but it helps you make informed decisions about which kratom products suit your preferences and how to use them responsibly.

For more information on kratom strains and composition, check out our active compounds scientific analysis and beginner's guide to kratom.

Disclaimer: These statements have not been evaluated by the FDA. Kratom is not intended to diagnose, treat, cure, or prevent any disease. Consult a healthcare professional before using kratom, especially if you have medical conditions or take medications. Must be 21+ to purchase. Not available in all states.