Subclass of Phenolics

Chalcones

Open-chain flavonoid precursors, often yellow pigments with anti-inflammatory activity.

Overview

About Chalcones

Chalcones are the open-chain form of a flavonoid — two aromatic rings joined by a three-carbon bridge that has not yet closed into the third ring. They are the biosynthetic entry point to the entire flavonoid family: chalcone synthase makes them, chalcone isomerase folds them shut, and everything else follows.

Some plants leave a portion unfolded, and those free chalcones accumulate as yellow pigments with a distinct pharmacology of their own — including a reactivity the cyclized flavonoids lose.

Where Chalcones Occur

A scattered group, concentrated in a few well-studied plants:

Liquorice

licochalcone A and B, isoliquiritin

Hops

xanthohumol and desmethylxanthohumol

Kava

the flavokawains

Angelica keiskei (ashitaba)

the prenylated chalcones

Safflower and dahlia

the classic yellow chalcone pigments

Apple and Russian tarragon

phloretin and the dihydrochalcones

The Reactive Bridge

The unclosed three-carbon bridge carries an α,β-unsaturated ketone — a Michael acceptor, the same reactive motif that makes sesquiterpene lactones what they are. It reacts with cysteine thiols on proteins.

That single feature explains most chalcone pharmacology: covalent inhibition of NF-κB signalling, activation of Nrf2 by modifying its Keap1 sensor, and — at the other end — the cytotoxicity and hepatocyte damage that some members show. Cyclize the chalcone into a flavanone and the reactivity largely disappears.

Pharmacological Importance

Licochalcone A is among the better-characterized plant anti-inflammatories, with a real formulation record in topical anti-redness and anti-acne products. Licochalcone B disrupts the NEK7–NLRP3 interaction, making it an unusually selective inflammasome inhibitor.

Xanthohumol has a broad preclinical metabolic and chemopreventive literature, though it is complicated by its spontaneous isomerization to isoxanthohumol and onward bacterial conversion to 8-prenylnaringenin — one of the most potent phytoestrogens known, produced in the gut rather than the plant.

Toxicity & Safety

Dietary chalcone exposure is low and unproblematic. The class's cautionary case is flavokawain B, the kava chalcone that depletes glutathione and is cytotoxic to hepatocytes — a leading candidate for kava's hepatotoxicity signal, and one that tracks with aerial-part material, tudei cultivars and solvent extraction rather than with traditional water-based root preparations.

The Michael-acceptor chemistry also means chalcones should not be assumed benign by association with dietary flavonoids; judge them individually.

Constituents

All Chalcones

15 total Filter chalcones

Aspalathin 1 herb

Davidigenin 1 herb Desmethylxanthohumol 1 herb DMC-2 DMC-2 dihydrochalcone 1 herb

Flavokawain A 1 herb Flavokawain B 1 herb Flavokawain C 1 herb

Isoliquiritin 1 herb Isosalipurposide 1 herb

Kukulkanin B 1 herb

Licochalcone A 1 herb Licochalcone B 1 herb

Nothofagin 1 herb

Xanthohumol 1 herb

Open in filterable index

Source Plants

Herbs Containing Chalcones

7 herbs

Plants in the materia medica documented to carry chalcones, with the compounds each one is listed for. The bar counts how many DISTINCT chalcones are on record for a plant, relative to the best-documented — it measures breadth of record, not potency, so a plant with one well-studied compound can outrank a richer source that has simply been analysed less. Where a measured concentration is on record it is quoted inline; most entries have none yet.