Kratom Alkaloids

What is an alkaloid?

An alkaloid is a nitrogen-containing compound a plant builds as part of its own chemistry. Caffeine is one. So are quinine and nicotine. The word names a chemical family, not a purpose.

Kratom’s belong to a subgroup called indole alkaloids, named for a ring structure they share. A 2023 profiling study out of Malaysia found them to be the most abundant alkaloid subclass in the leaf.

Plants don’t make alkaloids for us. They tend to build up in the parts of a plant most exposed to insects and grazing animals. That is a defense argument, not a nutritional one. The leaf being useful to anyone is incidental to why the tree makes what it makes.

Which alkaloids does kratom leaf contain?

Kratom leaf holds far more than the two alkaloids most pages name. The DEA’s own fact sheet puts the count at no fewer than 54 isolated to date. That same 2023 Malaysian study annotated 63 alkaloid features in a single set of leaves.

A 2022 University of Florida trial measured nine of them by mass spectrometry. The list runs mitragynine, 7-hydroxymitragynine, speciogynine, paynantheine, speciociliatine, mitraphylline, corynantheidine, isocorynantheidine and corynoxine. Seven of those names appear on almost no retail page anywhere.

One result from that trial is worth sitting with. In those plants, speciogynine and mitraphylline each measured higher per unit of leaf dry mass than mitragynine did. Read that carefully before carrying it anywhere. Those were nursery plants raised in a greenhouse for a controlled experiment. The leaf that reaches a US shelf grows on mature trees standing in Southeast Asian forest, not on a plantation in Florida. So the figures aren’t a reading of what people actually buy. What the trial does show is that the two-alkaloid summary is a summary.

What is mitragynine?

Mitragynine is the alkaloid kratom leaf holds most of, at roughly 66 percent of total alkaloid content.

At the receptor, it binds mu-opioid receptors with partial agonist activity. That’s how a 2025 University of Florida paper describes it. The same paper notes that 7-hydroxymitragynine, its structural analog, binds that receptor more strongly, and that its concentration in nature is typically low.

That is where this page stops. What a compound does at a receptor is not a description of what happens to a person, and it should not be read as one.

What is 7-hydroxymitragynine?

7-hydroxymitragynine is a minor alkaloid of the leaf, under 2 percent of total alkaloid content. In practice it’s often not detectable at all.

In the 2022 University of Florida trial it sat below the lower limit of quantification in every lighting condition tested. Nine alkaloids were measured and that one never registered. A 2025 study from the same group found it averaging 0.02 to 0.04 percent in leaf alkaloid extracts. It turned up in certain seasons only, and which seasons depended on the cultivar.

Where it comes from is unsettled in the literature. The 2025 authors put the question in two halves. Does the plant make it, or does it form after harvest through oxidation? Several studies point at the second reading. Those authors also note a problem with the papers that report it in fresh leaves. Those leaves weren’t preserved immediately after picking. The sample may have kept changing before anyone measured it.

One thing has to be said plainly, because the name gets used two ways. 7-OH is also the label on a category of concentrated and synthesized products. Those aren’t kratom leaf. Whole Earth Gifts does not sell them and does not defend them. Federal action has reached those products and not the leaf, and that’s covered on is kratom legal federally.

Why do the numbers change from one batch to the next?

Alkaloid content isn’t a fixed property of the species. It moves, and the reasons have been measured rather than guessed at.

Light changes it. In the 2022 Florida trial, shaded plants carried 40 percent more mitragynine per unit of leaf dry mass than plants in full sun. Paynantheine ran 35 percent higher and corynoxine 111 percent higher. Four of the nine alkaloids showed no significant response to light at all.

Leaf age changes it. The 2023 Malaysian study compared young and mature leaves from the same tree. The two stages separated at 92.8 percent on principal component analysis, which means they’re chemically distinct. Mitragynine came in 1.2 times higher in the mature leaves and 7-hydroxymitragynine 3.3 times higher. Those are relative abundances from untargeted profiling rather than concentrations. Read them as direction, not as a measurement.

Season and genetics change it. The 2025 study found 7-hydroxymitragynine in specific seasons only, and the seasons differed by cultivar.

What happens after the leaf is picked changes it too. In that same study, letting leaves wither for 12 hours before drying raised mitragynine by 14 to 65 percent in one cultivar and 3 to 8 percent in another. Drying below 104 degrees Fahrenheit preserved mitragynine, speciogynine and paynantheine. Higher temperatures did not. Where a leaf grew is one input, and there’s more on that in where does kratom come from. What a drying shed did with it is another, and it’s the one nobody talks about.

What does an alkaloid number on a lab report mean?

A number on a certificate of analysis describes one lot of material and nothing beyond it.

A question that comes to us by phone, email and chat is why two lots of the same product are not identical, or why two orders from one lot are not. Part of the answer is everything above. The rest is how kratom gets made. A botanical capsule filled in a US plant is blended by machinery. That machinery is built to combine large volumes and mix them uniformly. Kratom powder doesn’t go through that. The leaf is dried and milled at origin and arrives already made.

Our own lots bear that out. Mitragynine on a Whole Earth Gifts certificate of analysis has run between 1.4 and 1.6 percent, and it steps outside that range only rarely. Inside it, no two lots read the same. That is a narrow band and it’s a real one. A narrow band is not the same thing as identical. Consistency in this trade is something you chase and mostly reach. It is not something the supply chain hands you the way a regulated factory line does.

There’s a second reason a number moves, and it has nothing to do with the leaf. No single industry standard method exists for testing kratom, so the same material can return different figures from different laboratories. That is a question about the measurement rather than about the material, and it’s covered in kratom lab testing.

What none of that changes is why the lots differ in the first place, which is the subject of kratom batch variation.

What the alkaloid numbers don’t tell you

An alkaloid figure describes chemistry. It does not describe a person. No study establishes what a given percentage does for anyone.

Color names aren’t alkaloid grades. White, green, red and gold describe when a leaf was picked and how it was dried. The chemistry behind those words is covered in kratom colors.

Strain names aren’t chemical categories either. Nothing on a retail shelf is sold as a botanical cultivar. The naming is covered in kratom strain names.

A two-number panel is a short list. With over 50 alkaloids identified and 63 annotated in one study, a report naming two of them is telling you about two of them.