Flavones Explained: Fifteen Carbons And One Empty Position
Definition
A flavone is a flavonoid built on a fifteen-carbon frame, with a double bond and a ketone group at position 4 of its C ring, the B ring attached at position 2, and position 3 left unsubstituted [1]. Apigenin and luteolin are the two standard examples [1]. Change what sits at position 3, or move the B ring one carbon along, and the compound picks up a different subclass name [1].
A definition you can draw on paper
A flavone is a flavonoid built on a fifteen-carbon frame: three rings, a double bond and a ketone group at position 4 on the C ring, the B ring attached at position 2, and position 3 left unsubstituted [1]. That is the full definition. Nothing else needs adding.
Start with that skeleton and the rest of the flavonoid family becomes readable [1]. Learn it in any other order and the names arrive as a list of unrelated chemicals with nothing holding them together.
One item of vocabulary, worth getting right on the first pass. Flavonoid is the umbrella term for the whole group. Flavone is one subclass inside it. The family label came from this parent compound, not the other way round, which is why the two words look so alike and get swapped so often [1].
Position 3 is the hinge. Leave it bare and the compound is a flavone. Hang a hydroxyl group there and it belongs to a different subclass with its own named members [1]. Move the B ring one carbon along, from position 2 to position 3, and you have crossed into another class again [1].
Draw it once and the pattern sticks. The double bond and the ketone at position 4 stay put across the group [1]. What moves, or gets added, is everything around them, and each of those small edits carries a class name of its own [1].
Two names carry most of the textbook descriptions of this group: apigenin and luteolin [1]. Both are flavones in the strict structural sense above. Both turn up in culinary herbs and flowering plants.
As pigments, flavones are pale [1]. That is easy to misread. The colour they contribute looks subtle to human eyes and rather less subtle to insects, whose vision covers ranges ours does not [1]. Inside the plant these molecules are doing real work, not decorating a petal for our benefit [1].
One edit, one new class name
| Change at the skeleton | Resulting class | Names on record | Reading note |
|---|---|---|---|
| Nothing moved and nothing added: double bond plus ketone at position 4 on the C ring, B ring joined at position 2, position 3 unsubstituted | Flavone | Apigenin, luteolin [1] | This is the reference point for the whole family. Every other row here is written as a departure from it [1]. |
| A hydroxyl group added at position 3, with the rest of the frame left exactly as it stands | Flavonol | Quercetin, kaempferol [1] | One oxygen and one hydrogen on a single carbon, and the subclass name changes. The skeleton underneath is otherwise identical [1]. |
| The B ring detached from position 2 and joined at position 3 instead | Isoflavone | Not named in the sources cited on this page | Same ring, different attachment point. That one carbon shift is enough to earn a separate class name [1]. |
| Prenyl side chains added to the flavone frame, with the position 2 attachment and the position 4 ketone both kept | Prenylated flavone | Cannflavins, recorded among the chemical constituents of cannabis [2] | The flavone definition still holds underneath. The branches are added, not swapped in [2]. |
| Fifteen carbons in three rings, read before any of the edits above | Flavonoid, the umbrella group | Flavones, flavonols and isoflavones all qualify [1] | Flavonoid is the family, flavone the branch, and the family took its name from the branch [1]. |
| No change at all: the position 4 ketone and the C ring double bond stay in place across the subclasses listed above | Shared frame | Apigenin, luteolin, quercetin, kaempferol [1] | Useful when a structure looks unfamiliar on the page. Locate the ketone first, then work outwards [1]. |
Cannflavins under a magnifying glass
| Point | What the cited chemistry records | Ref |
|---|---|---|
| Structural class | Cannflavins sit inside the flavone group rather than in a category of their own, because the frame underneath them is the standard flavone skeleton | [2] |
| B ring attachment | Joined at position 2, the same attachment point that defines apigenin and luteolin | [1][2] |
| Ketone | Present at position 4 on the C ring, as it is in every member of the flavone group | [2] |
| Side chains | Prenyl groups branch off the frame, and this is the feature that tells a cannflavin apart from the two herb garden flavones | [2] |
| Where they were described | Listed among the constituents of cannabis catalogued by ElSohly and Slade in 2005, alongside the cannabinoids in the same plant | [2] |
| Discussion context | They come up around the entourage effect, the idea that cannabis compounds act as a group rather than one compound at a time | [2] |
| Open question | Whether these prenylated flavones occur in plants other than cannabis is a question the general flavonoid overview does not settle | [1] |
| Reading the name | Cannflavin reads as a flavone found in cannabis, and the structure rather than the source is what fixes the classification | [1][2] |
| Comparison in one line | A prenylated flavone on one side, plain apigenin and luteolin on the other, with the same three rings shared between them | [1][2] |
Six checkpoints on a flavone skeleton
The naming runs in one direction only. Flavone came first as a compound, and the family label was built on top of it, which is why every other definition in this corner of plant chemistry reads as a departure from that one frame [1].
Cannflavins are the interesting edge case. Structurally they are flavones: B ring at position 2, ketone at position 4, prenyl side chains branching off the skeleton [2]. ElSohly and Slade catalogued them among the constituents of cannabis in 2005, in the same work that discusses the entourage effect, meaning cannabis compounds acting as a group rather than in isolation [2].
Whether the same prenylated flavones appear elsewhere in the plant kingdom is not something the broad flavonoid literature resolves, and the overview by Panche and colleagues from 2016 leaves that question open [1]. So the honest answer is that we do not know yet.
Hemp chemistry has more columns than the cannabinoid ones. Since 2014 we have worked with hemp extracts and published what each batch contains, and flavones belong to the wider plant profile sitting next to those numbers.
- Count the carbons. Fifteen, arranged in three rings, is the entry requirement for the flavonoid group as a whole [1].
- Read the C ring. A double bond and a ketone group at position 4 are the fixed features of the flavone frame [1].
- Find the B ring. Attached at position 2 you have a flavone; moved along to position 3, the compound is an isoflavone [1].
- Check position 3. Bare, it stays a flavone; carrying a hydroxyl group, it is a flavonol, the subclass of quercetin and kaempferol [1].
- Compare against the reference pair. Apigenin and luteolin are the flavones that textbook descriptions of the group lean on [1].
- Look for side chains. Prenyl groups on that same frame are what separate the cannflavins of cannabis from the herb garden flavones [2].
Frequently Asked Questions
3 questionsWhich position on the skeleton separates a flavone from a flavonol?
Is apigenin a flavone or a flavonoid?
Why are cannflavins classed alongside apigenin and luteolin?
About this article
Luke Sholl has been writing about cannabinoids, CBD, and the broader benefits of nature since 2011. His background includes first-hand cannabis cultivation experience spanning the full seed-to-harvest lifecycle across so
This wiki article was drafted with AI assistance and reviewed by Luke Sholl, CBD & wellness writer. Editorial oversight by Joshua Askew.
Medical disclaimer. This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before use of any substance.
Last reviewed August 27, 2026
References (2)
- [1]Panche, A.N., Diwan, A.D. and Chandra, S.R. (2016). Flavonoids: an overview. DOI: https://doi.org/10.1017/jns.2016.41
- [2]ElSohly, M.A. and Slade, D. (2005). Chemical constituents of marijuana: the complex mixture of natural cannabinoids. DOI: https://doi.org/10.1016/j.lfs.2005.09.011
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