Flavonoids: what they are and which ones are found in cannabis

Flavonoids are one of the largest groups of compounds made by plants. They give colour to berries, fruit and flowers, protect the plant from the sun’s UV radiation and are found in everything from tea to onions. Cannabis and hemp contain flavonoids too, including a few that are found almost nowhere else. Here we look at what flavonoids are, which ones occur in cannabis and what the research actually knows about them.

What are flavonoids?

Flavonoids are a group of polyphenols, meaning compounds with several phenol rings in their chemical structure. Plants make them to cope with their environment. Some flavonoids act as pigments that attract pollinators, while others protect the leaves against UV light or against fungi and pests. We take in flavonoids through fruit, berries, vegetables, tea, cocoa and red wine, among other things.

The name comes from the Latin flavus, meaning yellow, because many of the first known flavonoids produced yellow colours. In 1936 the Hungarian researchers István Rusznyák and Albert Szent-Györgyi published a paper in Nature on compounds from citrus fruit that they called vitamin P. The label was later dropped, as the compounds do not meet the definition of a vitamin, but the paper is regarded as the starting point of flavonoid research.

Different groups of flavonoids

All flavonoids share the same basic skeleton: two aromatic rings joined by a chain of three carbon atoms. Depending on how that structure is built, they are divided into groups:

• Flavones, such as apigenin and luteolin, are found in parsley, celery and chamomile.
• Flavonols, such as quercetin and kaempferol, are found in onions, kale and apples.
• Flavanones, such as naringenin and hesperetin, are found mainly in citrus fruit.
• Flavan-3-ols, such as catechins, are found in tea and cocoa.
• Anthocyanins give blue, purple and red colours to berries, grapes and red cabbage.
• Isoflavones are found mainly in soybeans and other legumes.

Which flavonoids are found in cannabis?

Cannabis and hemp contain several flavonoids that also occur in other plants, above all flavones and flavonols such as apigenin, luteolin, kaempferol and quercetin. Levels vary between strains, plant parts and growing conditions. On top of these there is a group of flavonoids that is relatively unique to cannabis: the cannflavins.

Cannflavins

Cannflavins A and B were first isolated in 1986 by British researchers, from a cannabis extract that contained no cannabinoids. Cannflavin C was described in 2008 by researchers at the University of Mississippi. Cannflavins are prenylated flavones, meaning they carry an extra carbon chain attached to the molecule, and it is that chain that sets them apart from ordinary flavones.

In 2019 researchers at the University of Guelph in Canada mapped how the plant makes cannflavins A and B. Luteolin is first converted into a compound called chrysoeriol, which then receives its extra carbon chain. As cannflavins occur only in small amounts in the plant, this knowledge matters to anyone who wants to produce them on a larger scale.

In the original 1986 study, cannflavins A and B inhibited the production of the inflammation-related compound prostaglandin E2 in cultured cells. Later laboratory studies have pointed in the same direction. These are, however, test-tube and cell-culture experiments, and there are no studies showing how cannflavins act in humans.

Flavonoids and the colour of cannabis

Flavonoids contribute to the colour of the cannabis plant. Anthocyanins can give purple or reddish tones to the leaves and flowers of some strains, and the colour often becomes more pronounced when nights are cool during flowering. How much colour a plant develops is governed mainly by genetics, but growing conditions also play a part.

Flavonoids and terpenes: the difference

Flavonoids and terpenes are often mentioned together, but they are two different groups of compounds. Terpenes are volatile and evaporate easily, and they are what gives cannabis its scent, whether citrusy, earthy or spicy. Flavonoids are largely non-volatile and therefore affect colour more than aroma. You can read more about terpenes in

What are terpenes, and which ones are found in cannabis?

Both terpenes and flavonoids are mentioned in connection with the entourage effect, the theory that the plant’s different compounds work together and enhance each other, so that the whole does more than a single isolated compound. Researchers at the University of California have pointed out that the role of flavonoids in the entourage effect in particular has been little studied, so there is a lot left to explore.

Flavonoids in CBD products

In CBD flowers, flavonoids remain naturally, together with cannabinoids and terpenes. In extracts, the content depends on how the product is made. Broad-spectrum and full-spectrum extracts keep more of the plant’s compounds, while an isolate consists of pure CBD without flavonoids or terpenes. If you want to know more about cannabinoids, the plant’s best-known compounds, we have put it all together in

What are cannabinoids? CBD, THC, CBG, CBN and the endocannabinoid system

Further down the page you can see a selection of our CBD flowers.

Sources

• Rusznyák, S. and Szent-Györgyi, A. (1936). Vitamin P: Flavonols as Vitamins. Nature, 138, 27.
• Barrett, M. L., Scutt, A. M. and Evans, F. J. (1986). Cannflavin A and B, prenylated flavones from Cannabis sativa L. Experientia, 42(4), 452–453.
• Radwan, M. M. et al. (2008). Non-cannabinoid constituents from a high potency Cannabis sativa variety. Phytochemistry, 69(14), 2627–2633.
• Rea, K. A. et al. (2019). Biosynthesis of cannflavins A and B from Cannabis sativa L. Phytochemistry, 164, 162–171.
• Bautista, J. L., Yu, S. and Tian, L. (2021). Flavonoids in Cannabis sativa: Biosynthesis, Bioactivities, and Biotechnology. ACS Omega, 6(8), 5119–5123.
• Panche, A. N., Diwan, A. D. and Chandra, S. R. (2016). Flavonoids: an overview. Journal of Nutritional Science, 5, e47.