Cannabis Alkaloids: What Researchers Know—and What Remains Uncertain

Cannabis is best known for cannabinoids such as THC and CBD, but those compounds are only part of the plant’s chemistry. Cannabis also produces nitrogen-containing substances known as alkaloids, a broad class that includes caffeine, nicotine, morphine, quinine and ephedrine.

Interest in cannabis alkaloids is longstanding, but the evidence remains limited. A 2021 review of cannabis chemistry described alkaloids as minor, non-cannabinoid constituents of Cannabis sativa and emphasized that their structures, distribution and biological effects are still incompletely understood.

What makes an alkaloid different?

Alkaloids are a chemically diverse group of natural products. Most contain nitrogen and many are basic, meaning they can react with acids. Their bitterness may help some plants deter herbivores, although the biological role of every alkaloid is not known.

Cannabinoids belong to a different chemical family. THC, CBD and related compounds are largely nonpolar and lipid-soluble, while many alkaloids have more polar, nitrogen-based structures. The distinction matters because a plant’s cannabinoids, terpenes, phenolics and alkaloids can behave differently during extraction, storage and metabolism.

It is also misleading to treat smoking as a general extraction method. Combustion releases some compounds while simultaneously degrading or transforming others. Laboratory researchers instead isolate cannabis constituents using methods such as solvent extraction, chromatography and spectroscopy.

A small and disputed group of compounds

More than 500 compounds have been reported in cannabis, including cannabinoids, terpenes, flavonoids and other phenolic substances. The number of recognized alkaloids is less certain because researchers have used different definitions and analytical methods. Some compounds reported in older literature are simple nitrogen-containing substances, while others are more complex molecules traditionally classified as alkaloids.

That uncertainty is one reason broad claims about “cannabis alkaloids” should be treated cautiously. The presence of a nitrogen-containing compound does not, by itself, demonstrate that it contributes meaningfully to cannabis’s intoxicating or therapeutic effects.

Early discoveries

Reports of cannabis-associated alkaloids go back to the late 19th century, including historical accounts of compounds called cannabinine and tetanocannabin. However, the modern research record is easier to document from the 1970s onward.

In a 1971 letter in Nature, researchers reported isolating four substances from cannabis alkaloid mixtures and named them cannabimines A through D. The original Nature paper provided molecular-weight data but did not establish complete structures for the compounds.

In 1975, scientists reported isolating and identifying cannabisativine from cannabis root. It was characterized as a spermidine alkaloid—a type of polyamine-related natural product. A related compound, anhydrocannabisativine, was subsequently isolated from the leaves and roots of a Mexican cannabis variant; its structure was described in a 1978 paper in the Journal of Pharmaceutical Sciences.

These findings helped establish that cannabis roots and other non-flowering tissues contain chemistry distinct from the resin-rich flowers typically studied for cannabinoids and terpenes.

Where are they found?

Available research suggests that cannabis alkaloids are concentrated more heavily in roots than in flowers. They have also been detected in stems, leaves and seeds, although levels can vary with genetics, growing conditions, plant age and analytical technique.

This distribution is important for interpreting older studies. A root extract containing cannabisativine or anhydrocannabisativine is not equivalent to a conventional cannabis flower product, and results from a concentrated laboratory extract cannot automatically be applied to human consumption.

Do cannabis alkaloids have medical effects?

Some laboratory and animal studies have reported biological activity from cannabis alkaloid preparations, including analgesic, diuretic, antipyretic, antiemetic and anticancer effects. But these findings generally involve isolated compounds, crude extracts or preliminary experiments—not well-controlled clinical trials in people.

Recent work continues to examine the subject. For example, a 2025 study of alkaloid-enriched extracts from cannabis roots investigated inhibition of the enzymes acetylcholinesterase and butyrylcholinesterase. Such results may help researchers identify mechanisms worth studying, but they do not establish that cannabis alkaloids treat disease or produce a clinically useful “entourage” effect.

The most accurate conclusion is therefore a modest one: cannabis contains a small, chemically varied and understudied group of alkaloids. Researchers have identified several compounds and found intriguing activity in laboratory models, particularly in root extracts. Yet their concentrations in the plant, effects in humans, safety profiles and contribution to cannabis pharmacology remain unresolved.