Compound Monograph
Myricetin
A widely distributed dietary flavonol — the "pyrogallol" flavonol whose three-hydroxyl B-ring makes it both a strong antioxidant and, at high concentration, a pro-oxidant and genotoxin. No isolate trials in humans; the evidence is dietary epidemiology (mixed on type-2 diabetes) plus preclinical anticancer and antiviral mechanism. Poorly and erratically absorbed.
Sources · 12
Where Does It Come From?
Myricetin is a naturally occurring flavonoid (flavonol), found in Fennel, Parsley, Cranberry, blueberry & black currant and 9 other sources. It is well tolerated orally (low toxicity).
Principal source Fennel Foeniculum vulgare Herb monograph →
Source Bearberry Arctostaphylos uva-ursi Herb monograph →
Source Blue Lotus Flower Nymphaea caerulea Herb monograph →
Source Gotu Kola Centella asiatica Herb monograph →
Source Guamura Cecropia obtusifolia Herb monograph →
Source Monterey Pine Pinus radiata Herb monograph → Concentration
Content by Source
Reported concentrations across the plants that contain myricetin — the bar marks the typical level, the line shows the reported range.
Literature figures for varying plant parts and preparations. Read them as a comparative guide, not exact assays.
Myricetin at a Glance
Myricetin is a widely distributed dietary flavonol found in berries, walnuts, tea and red wine.
Its chemistry is the reason it behaves differently from its relatives. Myricetin carries a pyrogallol B-ring — three adjacent hydroxyls where quercetin has two — which makes it a notably strong antioxidant at low concentrations and, at high ones, a pro-oxidant and genotoxin. The same feature drives both behaviours, so the direction depends on dose.
There are no trials of the isolated molecule in humans; its human evidence is dietary-intake epidemiology, which is mixed, with the laboratory work concentrated on metabolic and anticancer activity.
What It's Used For
Myricetin is one of the most broadly distributed dietary flavonols — the “pyrogallol” flavonol, defined by three adjacent hydroxyls on its B-ring (positions 3′,4′,5′). That one structural feature is the whole story: it makes myricetin an unusually strong metal-chelator and radical scavenger, and it is also what lets the molecule auto-oxidize, generate hydrogen peroxide and damage DNA at higher concentrations 1,
So the honest framing is a double-edge, not a simple “antioxidant.” Its human evidence is thin — there are no trials of isolated myricetin in people — and rests on dietary epidemiology, which is mixed 2,
Everything mechanistic (anticancer, antiviral, anti-inflammatory) is preclinical 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →.
Support is an experimental score I’m building — a composite weighted by study type (human > animal > in vitro > review) and study volume, tempered for isolate-vs-source match and bioavailability. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric. Scores here are held low because there is no isolated-myricetin human trial — the “Rests on” column names what each really tested. Each application links to its write-up.
Myricetin’s best-known “human” association is diabetes, and it is genuinely unresolved. In the EPIC-InterAct case-cohort — the large prospective European analysis — higher intake of flavonols (myricetin among them) was inversely associated with incident type-2 diabetes 2Reference 2Dietary intakes of individual flavanols and flavonols are inversely associated with incident type 2 diabetes in European populationsView study →.
But the Women’s Health Study (≈38,000 US women) found no significant association between flavonol/myricetin intake and diabetes risk 3Reference 3ObservationalAssociations of dietary flavonoids with risk of type 2 diabetes, and markers of insulin resistance and systemic inflammation in women — a prospective study and cross-sectional analysisView study →.
Both are large, prospective and well-conducted; they disagree. Preclinically myricetin improves insulin signaling and glucose uptake in rodent models 1,
Gap: this is dietary-intake epidemiology (people eating myricetin-containing foods, which also carry quercetin, fiber, etc.), not a trial of myricetin; the two best cohorts contradict each other; and there is zero interventional human evidence. Score held to reflect the conflict 2,
A large in-vitro/animal literature: myricetin induces apoptosis across cancer cell lines — and, revealingly, in triple-negative breast-cancer cells the mechanism is the iron-dependent generation of reactive oxygen species from hydrogen peroxide 6Reference 6Myricetin-induced apoptosis of triple-negative breast cancer cells is mediated by the iron-dependent generation of reactive oxygen species from hydrogen peroxideView study →. In other words the “anticancer” effect is the same pro-oxidant chemistry that shows up in the safety section — powerful in a dish at high concentration, not obviously benign, and not a clean “antioxidant” benefit.
Gap: the matching human evidence points the other way — a large prospective cohort found dietary flavonoid intake (including myricetin) not associated with total or site-specific cancer 5Reference 5Dietary intake of selected flavonols, flavones and flavonoid-rich foods and risk of cancer in middle-aged and older womenView study →. So: preclinical mechanism only, driven by a concentration-dependent pro-oxidant effect that oral dosing is unlikely to reproduce in tissue. Score kept in single-to-low double digits 5,
Among flavonols, myricetin is a repeat hit in antiviral enzyme screens. It inhibits the SARS-coronavirus helicase (nsP13) ATPase (IC₅₀ ≈ 2.7 µM) 7Reference 7Identification of myricetin and scutellarein as novel chemical inhibitors of the SARS coronavirus helicase, nsP13View study → and the SARS-CoV-2 main protease (Mpro) (IC₅₀ ≈ 3.7 µM), with reduced lung inflammation in a mouse model 8Reference 8Myricetin inhibits SARS-CoV-2 viral replication by targeting Mpro and ameliorates pulmonary inflammationView study →; the pyrogallol B-ring also inhibits other viral enzymes (e.g. reverse transcriptase) as reviewed 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →.
Gap: all of this is in-vitro enzyme, cell or mouse work at low-micromolar concentrations that myricetin’s poor, erratic oral absorption is unlikely to deliver to human tissue; there are no clinical antiviral data. Preclinical interest, not evidence of use 7,
Mechanisms
| Target / pathway | Effect | Relevant to | Evidence |
|---|---|---|---|
| Radical scavenging + Fe/Cu chelation (pyrogallol B-ring) | antioxidant at low concentration | general | in vitro |
| Auto-oxidation → H₂O₂; Cu/Fe-mediated ROS | pro-oxidant, DNA-damaging at high concentration | safetyanticancer | in vitro 6, |
| Topoisomerase-II poisoning | strand breaks (genotoxic) | safety | in vitro 10, |
| ↑ insulin signaling / GLUT4 glucose uptake | glucose lowering | diabetes | animal 1, |
| Viral enzyme inhibition (helicase, Mpro, RT) | antiviral | antiviral | in vitro/mouse 7, |
Pharmacokinetics
Myricetin is poorly and erratically absorbed, and its own chemistry works against it. In food it is stored mostly as glycosides that must be hydrolyzed before uptake, and the free aglycone is chemically fragile — the electron-rich pyrogallol B-ring auto-oxidizes readily in neutral/alkaline, aerobic conditions, so a fraction degrades before or during absorption 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →. What is absorbed is heavily conjugated: a rat pharmacokinetic study using enzymatic deconjugation measured an absolute oral bioavailability of only ~9.6% and confirmed extensive glucuronidation and sulfation 9Reference 9AnimalQuantitative determination of myricetin in rat plasma by UPLC-MS/MS and its absolute bioavailabilityView study →. As with the other flavonols, this means the circulation carries myricetin conjugates rather than much free aglycone, and the low-micromolar concentrations that drive its in-vitro mechanisms are difficult to reach in tissue from oral intake — the central reason its potent laboratory activity has not translated. (The headline ~9.6% figure is a rat value; there is no clean human bioavailability trial 9Reference 9AnimalQuantitative determination of myricetin in rat plasma by UPLC-MS/MS and its absolute bioavailabilityView study →.)
Clinical trials
None of isolated myricetin. The human evidence is entirely observational dietary epidemiology, and it does not agree with itself:
| Human diabetes evidence | Human cancer evidence | Isolate trials |
|---|---|---|
| EPIC-InterAct: inverse 2Reference 2Dietary intakes of individual flavanols and flavonols are inversely associated with incident type 2 diabetes in European populationsView study → · Women’s Health Study: null 3Reference 3ObservationalAssociations of dietary flavonoids with risk of type 2 diabetes, and markers of insulin resistance and systemic inflammation in women — a prospective study and cross-sectional analysisView study → | Women’s Health Study: null 5Reference 5Dietary intake of selected flavonols, flavones and flavonoid-rich foods and risk of cancer in middle-aged and older womenView study → | None |
Last checked: July 2026.
Isolate vs. Plant Studies
Myricetin is a textbook case for reading flavonol claims skeptically. The human data are dietary, not molecular: the diabetes and cancer associations come from food-frequency questionnaires, where myricetin travels with quercetin, kaempferol, fiber, vitamin C and everything else in berries and greens — so a signal can’t be assigned to myricetin, and here the two largest cohorts even disagree on diabetes 2,
Prevalence in Nature
Myricetin is a widely but unevenly distributed flavonol, usually present as glycosides (myricitrin and other myricetin glycosides) and released on hydrolysis 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →. It is not concentrated in one signature food the way some flavonoids are; instead it turns up across herbs, leafy vegetables, berries, tea and wine. By USDA analysis the richest common sources are fennel bulb (~19.8 mg/100 g) and parsley (~14.8 mg/100 g, lower-confidence data), followed by the berries — cranberry (~7.6), wild blueberry (~7.3) and black currant (~6.2 mg/100 g) — and leafy greens such as dock/sorrel (~5.7) and sweet-potato leaf (~2.9) 13,
Biosynthetically myricetin sits at the most-hydroxylated end of the common flavonol series. The enzyme flavonoid 3′,5′-hydroxylase (F3′5′H) adds hydroxyls at the 3′ and 5′ positions of the B-ring, converting the mono-/di-hydroxylated flavonols into the trihydroxy (pyrogallol) pattern: kaempferol → quercetin → myricetin corresponds to 1 → 2 → 3 B-ring hydroxyls 15Reference 15Hydroxylation decoration patterns of flavonoids in horticultural crops — chemistry, bioactivity and biosynthesisView study →. The same F3′5′H branch that yields myricetin also feeds the delphinidin/blue-anthocyanin and prodelphinidin lines, which is why myricetin-rich plants (currants, certain grapes) tend also to be rich in the blue-purple pigments.
Discovery & Synthesis
Myricetin takes its name from the plant genus Myrica — the bayberries or wax myrtles — and is reported to have been first isolated from the bark of Myrica nagi. That naming-and-first-isolation history is documented only in secondary/review literature rather than a primary indexed paper, so it should be treated as reported rather than firmly sourced 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →. Chemically myricetin is 3,3′,4′,5,5′,7-hexahydroxyflavone — the flavonol carrying six hydroxyl groups, three of them the adjacent 3′,4′,5′ pyrogallol cluster on the B-ring that defines its behavior. It is the B-ring 5′-hydroxy homologue of quercetin (which lacks the 5′-OH) and, two hydroxyls up, of kaempferol; reducing the C-ring 2,3-double bond gives the related dihydromyricetin (ampelopsin).
Isolated myricetin is a yellow solid that is notably unstable in solution — the pyrogallol B-ring oxidizes in air, especially at neutral-to-alkaline pH, which complicates both its formulation and the interpretation of assays where the “myricetin” tested may be partly oxidation products 1,
Patents: not yet researched (future patent-loop pass).
Toxicity & Safety
At the levels supplied by a normal diet, myricetin is a well-tolerated food constituent with a low toxicity profile — it has been eaten in berries, vegetables, tea and wine for as long as people have eaten those foods. The important caveat is specifically about concentrated, high-dose supplemental intake, where its defining chemistry cuts the other way.
The pyrogallol B-ring is pro-oxidant and genotoxic at high concentration. In cell-free and cellular systems myricetin auto-oxidizes to generate hydrogen peroxide and, in the presence of copper (or iron) ions, causes site-specific oxidative DNA damage 11Reference 11Myricetin causes site-specific DNA damage via reactive oxygen species generation by redox interactions with copper ionsView study →. It also acts as a topoisomerase-II poison — stabilizing the enzyme–DNA cleavage complex to produce DNA strand breaks — an activity tied directly to its B-ring hydroxylation pattern 10,
Because there are no human safety trials of isolated myricetin, the upper bound of safe supplemental intake is simply not characterized 1Reference 1Myricetin — a dietary molecule with diverse biological activitiesView study →. Like many flavonoids it can also inhibit drug-metabolizing enzymes and transporters in laboratory systems, so interactions with medications are plausible though not clinically quantified. The sensible reading: dietary myricetin is fine and probably beneficial; concentrated high-dose supplements are not well-characterized and carry a real, mechanism-based genotoxicity concern.
Dosage
There is no established dose of myricetin, because no human trial has ever tested the isolated compound. Typical dietary intakes of myricetin are on the order of a few milligrams per day, obtained from berries, leafy greens, herbs, tea and wine 14Reference 14USDA Database for the Flavonoid Content of Selected Foods, Release 3.3View study →. Supplement products exist but rest on animal and in-vitro data, not human dosing studies, and the pro-oxidant/genotoxicity signal at high concentration is a specific reason not to extrapolate upward from food to high-dose capsules 10,
| Context | Basis | Notes |
|---|---|---|
| Dietary intake | Food surveys | A few mg/day from berries, greens, herbs, tea, wine 14Reference 14USDA Database for the Flavonoid Content of Selected Foods, Release 3.3View study → |
| Supplemental | No human trials | Any dose is extrapolated from animal/in-vitro work; genotoxicity caveat applies 10, |
These are descriptive figures, not a recommendation — the honest position is that isolated-myricetin dosing in humans is unstudied.
References
- Semwal DK, Semwal RB, Combrinck S, Viljoen A. (2016). Myricetin — a dietary molecule with diverse biological activities. Nutrients, 8(2), 90. https://pubmed.ncbi.nlm.nih.gov/26891321/
- Zamora-Ros R, Forouhi NG, Sharp SJ, et al. (2014). Dietary intakes of individual flavanols and flavonols are inversely associated with incident type 2 diabetes in European populations. The Journal of Nutrition, 144(3), 335–343. https://pubmed.ncbi.nlm.nih.gov/24368432/
- Song Y, Manson JE, Buring JE, Sesso HD, Liu S. (2005). Associations of dietary flavonoids with risk of type 2 diabetes, and markers of insulin resistance and systemic inflammation in women — a prospective study and cross-sectional analysis. Journal of the American College of Nutrition, 24(5), 376–384. https://pubmed.ncbi.nlm.nih.gov/16192263/
- Ong KC, Khoo HE. (1997). Biological effects of myricetin. General Pharmacology, 29(2), 121–126. https://pubmed.ncbi.nlm.nih.gov/9251891/
- Wang L, Lee IM, Zhang SM, Blumberg JB, Buring JE, Sesso HD. (2009). Dietary intake of selected flavonols, flavones and flavonoid-rich foods and risk of cancer in middle-aged and older women. The American Journal of Clinical Nutrition, 89(3), 905–912. https://pubmed.ncbi.nlm.nih.gov/19158208/
- Knickle A, Fernando W, Greenshields AL, Rupasinghe HPV, Hoskin DW. (2018). Myricetin-induced apoptosis of triple-negative breast cancer cells is mediated by the iron-dependent generation of reactive oxygen species from hydrogen peroxide. Food and Chemical Toxicology, 118, 154–167. https://pubmed.ncbi.nlm.nih.gov/29742465/
- Yu MS, Lee J, Lee JM, et al. (2012). Identification of myricetin and scutellarein as novel chemical inhibitors of the SARS coronavirus helicase, nsP13. Bioorganic & Medicinal Chemistry Letters, 22(12), 4049–4054. https://pubmed.ncbi.nlm.nih.gov/22578462/
- Xiao T, Cui M, Zheng C, et al. (2021). Myricetin inhibits SARS-CoV-2 viral replication by targeting Mpro and ameliorates pulmonary inflammation. Frontiers in Pharmacology, 12, 669642. https://pubmed.ncbi.nlm.nih.gov/34220507/
- Dang Y, Lin G, Xie Y, et al. (2014). Quantitative determination of myricetin in rat plasma by UPLC-MS/MS and its absolute bioavailability. Drug Research, 64(10), 516–522. https://pubmed.ncbi.nlm.nih.gov/24357136/
- Bandele OJ, Clawson SJ, Osheroff N. (2008). Dietary polyphenols as topoisomerase II poisons — B-ring and C-ring substituents determine the mechanism of enzyme-mediated DNA cleavage enhancement. Chemical Research in Toxicology, 21(6), 1253–1260. https://pubmed.ncbi.nlm.nih.gov/18461976/
- Hirao Y, Kobayashi H, Mori Y, et al. (2023). Myricetin causes site-specific DNA damage via reactive oxygen species generation by redox interactions with copper ions. Mutation Research — Genetic Toxicology and Environmental Mutagenesis, 891, 503694. https://pubmed.ncbi.nlm.nih.gov/37770136/
- Constantinou A, Mehta R, Runyan C, Rao K, Vaughan A, Moon R. (1995). Flavonoids as DNA topoisomerase antagonists and poisons — structure-activity relationships. Journal of Natural Products, 58(2), 217–225. https://pubmed.ncbi.nlm.nih.gov/7769390/
- Häkkinen SH, Kärenlampi SO, Heinonen IM, Mykkänen HM, Törrönen AR. (1999). Content of the flavonols quercetin, myricetin and kaempferol in 25 edible berries. Journal of Agricultural and Food Chemistry, 47(6), 2274–2279. https://pubmed.ncbi.nlm.nih.gov/10794622/
- Haytowitz DB, Wu X, Bhagwat S. (2018). USDA Database for the Flavonoid Content of Selected Foods, Release 3.3. U.S. Department of Agriculture, Agricultural Research Service. [Database — no PMID.] https://www.ars.usda.gov/nutrientdata
- Liu Y, Qian J, Li J, et al. (2022). Hydroxylation decoration patterns of flavonoids in horticultural crops — chemistry, bioactivity and biosynthesis. Horticulture Research, 9, uhab068. https://pubmed.ncbi.nlm.nih.gov/35048127/
