Flavonoids: The C6-C3-C6 Family Behind Plant Colour
Definition
Two six-carbon rings joined by a three-carbon bridge: written as C6-C3-C6, that pattern is what makes a molecule a flavonoid. Three small edits to the same pattern sort the family into flavones, flavanones, flavonols and flavan-3-ols [1]. Flavonoid is the umbrella name for the whole group, not a single compound [2].
Two rings, one bridge: reading C6-C3-C6
| In the shorthand | In plain words | What it settles |
|---|---|---|
| C6, first block | Six carbon atoms closed into a ring | Fixed for the whole family, which is why one page can cover flavonoids as a group rather than one molecule at a time [2] |
| C3, the middle block | A bridge of three carbons running between the two rings | The working part of the pattern. The first of the three sorting edits happens on the middle ring [1] |
| C6, second block | A second six-carbon ring on the far end of the bridge | Also fixed, so the pattern always reads ring, bridge, ring, in that order |
| C6-C3-C6 written out | The line chemists use instead of redrawing the whole structure | One notation for a very large family of plant compounds, cannabis included in that story [1] |
| Three edits | Small changes made to the same starting pattern | They split the family into flavones, flavanones, flavonols and flavan-3-ols [1] |
| The separators | A double bond, a single bond, an added hydroxyl group | Those three details are what the subclass names actually record [1] |
| Colour | Absent from the shorthand entirely | It arrives with the subclass. Flavan-3-ols, for example, are recorded from colourless through to tan [1] |
| Relevance | Not bookkeeping for its own sake | The edits are relevant to the plant that makes them, not only to the person sorting them [1] |
| Names under the umbrella | Apigenin, luteolin, quercetin, kaempferol | All four sit inside the same family, in hemp and in many other plants [2] |
| Sugar-linked forms | The same core with a sugar attached to it | Recorded in hemp alongside the free forms, under the same family name [2] |
Three edits, four subclasses
| Subclass | The edit that names it | What is on record |
|---|---|---|
| Flavones | The middle ring keeps a double bond, which is edit one in the sorting sequence [1] | Apigenin and luteolin are the two names to hold onto here, and both have been recorded in hemp [2] |
| Flavanones | Same position, a single bond instead of the double bond [1] | One bond apart from the flavones, and a separate subclass because of it [1] |
| Flavonols | The flavone arrangement plus an added hydroxyl group [1] | Quercetin and kaempferol, present in hemp and in many other plants as well [2] |
| Flavan-3-ols | Hydroxyl group without the middle-ring double bond. The 3 in the name marks where it sits [1] | Catechins belong here, and the larger tannins are built from them [1] |
| Flavan-3-ols, colour | Not a pigment class in the usual sense | Logged as colourless through to tan, so they read as astringency and browning rather than as petal colour [1] |
| Flavan-3-ols, sources | Where the subclass is best documented | Green tea and black tea, cocoa, grapes and apples [1] |
| Flavanols | The other spelling for the same subclass | Two names, one group. Useful to know when you compare two ingredient lists side by side |
| Sugar-linked versions | The core with a sugar attached | Common in hemp next to the free forms, and counted under the same subclass [2] |
| Why the edits count | The changes look small on paper | They matter to the plant that produces them, which is the point of sorting by edit rather than by colour [1] |
Hemp's flavonoid entries, name by name
Apigenin, luteolin, quercetin, kaempferol
Four names carry most of the hemp list. Apigenin and luteolin are flavones. Quercetin and kaempferol are flavonols, one added hydroxyl group away from the flavones [1]. All four have been recorded in the plant, and they appear both on their own and in sugar-linked forms, where a sugar is bound to the flavonoid core [2].
None of them is a cannabis speciality. The same four names come back in many other plants [2]. Worth saying plainly. The flavonoid part of a hemp analysis often reads much like the flavonoid part of an ordinary leaf: same pattern, same subclasses, same three sorting edits [1]. Sugar-linked forms are also why one compound can appear under two slightly different names, depending on whether the sugar is still attached [2].
The side chain that points back to cannabis
The cannflavins are where the accounting changes. They carry a side-chain modification of the same type described in cannabinoid biosynthesis [2]. Flavonoid core, cannabinoid-style side chain.
So these are not flavonoids the plant collected somewhere else and relabelled. They are flavonoid chemistry built with the tools cannabis already uses for its better-known compounds [2]. Read that way, the ring pattern is the least interesting part of the molecule. Every flavonoid has the ring pattern. What differs is the side chain, plus which of the three edits the plant has made [1].
It also shows why the group name on its own is thin information. Flavonoid is an umbrella stretched across the plant kingdom [2]. Cannflavin is a specific address inside it.
What holds up when you check it
Flavonoid chemistry is old, well mapped and unglamorous. That is the useful part. The pattern is stable, the sorting rules are few, and the names follow the structure rather than the marketing. What the cited overviews describe is structure, distribution and the plant's own chemistry [1][2]. Since 2014 our own reports have measured cannabinoid content per batch, which is a different question and a different number. Keep the two apart and the topic stays clear.
- Flavonoid names a family, so a single name such as quercetin carries more information than the group label does [2].
- C6-C3-C6 tells you the shape and nothing about the source, which is why the plant name still has to be written next to it.
- Edit one sits on the middle ring, and the double bond, single bond or added hydroxyl group is what the subclass name records [1].
- Flavan-3-ols are the subclass behind green tea, black tea, cocoa, grapes and apples, where they turn up as astringency and browning rather than as bright pigment [1].
- Catechins are flavan-3-ols, and the larger tannins are assembled from them, so the two words describe one lineage [1].
- In hemp, apigenin, luteolin, quercetin and kaempferol are the recurring entries, free and sugar-linked [2].
- Cannflavins carry the side-chain modification also seen in cannabinoid biosynthesis, which makes them cannabis-shaped flavonoid chemistry rather than a borrowed molecule [2].
- A batch analysis quantifies what it was built to quantify, so read it for the cannabinoid figures and read the chemistry literature for the flavonoid sorting.
Frequently Asked Questions
4 questionsWhat does the shorthand C6-C3-C6 actually tell me?
Why does one subclass have two names, flavanols and flavan-3-ols?
Which flavonoids have been recorded in hemp?
Are flavan-3-ols responsible for the dry mouthfeel of strong tea?
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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