Mitragynine: Kratom's Main Alkaloid, Explained

Mitragynine is the most abundant alkaloid in the leaves of Mitragyna speciosa, the tree sold as kratom. This guide explains what the compound is, why its level changes from one batch to the next, and how laboratories measure it, so the numbers on a Certificate of Analysis make sense when you read them.

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Plants make thousands of natural compounds. Alkaloids are one large family of them: nitrogen-containing molecules that many plants produce, including coffee, cacao and tea. Mitragynine belongs to a sub-group called monoterpene indole alkaloids. In fact, kratom leaf contains more of it than any other compound.

Scientists first isolated mitragynine from the leaf in the early twentieth century. Decades later, researchers confirmed its full chemical structure with modern analytical methods. It sits mainly in the leaves rather than the bark or stems. For this reason, kratom reaches buyers as dried, milled leaf.

Mitragynine takes its name from the genus Mitragyna. Similarly, many plant compounds take the name of the plant where scientists first found them. When a laboratory report or an article mentions “total alkaloids” for kratom, mitragynine is usually the largest single share of that figure.

Mitragynine is not alone. In fact, researchers have identified dozens of related alkaloids in Mitragyna speciosa, and a handful appear in meaningful amounts. For example, one published analysis of commercial kratom products and extracts measured these ranges by weight:

• Mitragynine: roughly 0.7% to 38.7%, the widest range and the highest share;
• Paynantheine: roughly 0.3% to 12.8%;
• Speciociliatine: roughly 0.4% to 12.3%;
• Speciogynine: roughly 0.1% to 5.3%.

However, the very top of those ranges comes from concentrated extracts, not plain leaf. Natural leaf also contains a trace amount of 7-hydroxymitragynine, a separate alkaloid. Sometimes it appears for sale in concentrated, lab-made form as “7-OH”. That is a different product category from kratom leaf, and Kratom Delivery Canada does not sell it. Our 7-OH explainer sets out the difference.

Two bags of kratom that look identical can carry quite different amounts of mitragynine. Published research points to several reasons:

• Season: a study of trees in Thailand found mitragynine at its highest in the late dry season and at its lowest in the rainy season;
• Geography and soil: trees grown in different regions produce different alkaloid profiles;
• Genetics: researchers have described distinct chemical types, or chemotypes, of the species;
• Leaf age: harvesters pick younger and older leaves at different points in the growth cycle;
• Drying and storage: alkaloids can break down over time with heat, light, air and moisture.

This natural variation is the main reason a single, batch-specific lab result tells you far more than a general description of a strain name. It also explains why the same named product can test differently from one shipment to the next. See how kratom leaf becomes powder for where drying and storage fit in.

Testing laboratories do not estimate mitragynine by colour or smell. Instead, they separate the compounds in a prepared sample and measure each one against a certified reference standard. The two methods you will see named most often are:

• HPLC (high-performance liquid chromatography), a long-established method for measuring plant compounds;
• LC-MS/MS or UPLC-MS/MS (liquid chromatography with tandem mass spectrometry), which can measure many alkaloids at once, including trace compounds.

Laboratories normally report results as a percentage by weight (% w/w) or in milligrams per gram (mg/g). One percent equals 10 mg/g, so a result of 1.5% and 15 mg/g describe the same batch. However, the figure only applies to the sample the laboratory tested. For this reason, a report needs a batch or lot number that matches the product you receive.

A Certificate of Analysis (COA) is the laboratory report for a specific batch. When you look at the mitragynine line, check the details around it as well as the number:

• Batch or lot number that matches your package;
• Test date, recent enough to reflect the current stock;
• Method named on the report, such as HPLC or LC-MS/MS;
• Laboratory name and contact details, so you can trace the report;
• Contaminant screening for heavy metals and microbes, which matters as much as the alkaloid result.

Also, be wary of reports with no batch number, suspiciously round figures, or no laboratory named at all. Our guide to reading a kratom COA walks through a full report line by line.

Mitragynine does not appear in the schedules of Canada’s Controlled Drugs and Substances Act. In addition, you can legally buy and own kratom leaf in Canada. Health Canada has not authorized kratom products for human consumption. Therefore, sellers offer kratom for research and botanical purposes, and they cannot market it with health claims.

For the full picture, including what that means for ordering and delivery, read Is kratom legal in Canada?. For the plant the compound comes from, see Mitragyna speciosa: the kratom tree.

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