Leonuride

Leonuride at a Glance

Leonuride is a bitter iridoid glucoside of the catalpol type, better known in the pharmacology literature by its synonym ajugol. It is a marker constituent of motherwort (Leonurus cardiaca and the TCM species L. japonicus) and is also one of the more abundant iridoids in the roots of rehmannia (Rehmannia glutinosa), with further occurrence across the genus Ajuga, from which it takes its name.

For most of its history leonuride was treated as a minor, largely inert marker — the bitter principle contributing to motherwort’s flavour and part of the traditional case for the herb as a calming, “heart-easing” bitter ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. Since 2021, however, a small but internally consistent run of isolated-ajugol studies has given it a genuine preclinical profile: rodent models of asthma, non-alcoholic fatty liver disease, osteoarthritis and Alzheimer-type neuroinflammation, converging on two recurring mechanisms — TFEB-driven autophagy/lysosomal biogenesis and suppression of NF-κB/inflammasome inflammatory signalling ^{2,3,4,5Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →Reference 5Han X et al. · 2025Systems pharmacology identifies ajugol-mediated NF-κB/caspase-3 inhibition and isoacteoside-driven p62/mTOR-mediated autophagy as key mechanisms of Rehmanniae Radix and its processed form in Alzheimer’s treatmentView study →}.

Two honest caveats frame everything below. There are no human trials of the isolate, and — importantly — motherwort’s cardiovascular and uterine reputation belongs to the whole herb and its alkaloids (leonurine, stachydrine), not to this iridoid ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. As a poorly-absorbed glucoside, leonuride’s in-vitro and high-dose rodent potency also overreads what an oral dose plausibly delivers ^{6,7Reference 6Wang C et al. · 2020Iridoids: research advances in their phytochemistry, biological activities, and pharmacokineticsView study →Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →}.

Leonuride (Ajugol), a Motherwort Iridoid

The single most useful framing for this molecule is that leonuride and ajugol are the same compound — a catalpol-type iridoid glucoside — appearing under two names because it was characterised independently in different plant genera. The name ajugol derives from the genus Ajuga (bugleweed); leonuride flags its role as an iridoid marker of Leonurus (motherwort). Structurally it sits in the catalpol family of iridoid glucosides, alongside aucubin and catalpol, and it co-occurs with these compounds in Rehmannia root ^{7,8Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →Reference 8Liu YF et al. · 2024Four new iridoid glycosides from the roots of Rehmannia glutinosaView study →}.

In motherwort, leonuride is the herb’s characteristic iridoid, and the bitter iridoid fraction is part of what earns Leonurus its traditional reputation as a calming, mildly hypotensive bitter ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. This is exactly where the isolate-vs-whole-herb discipline matters most:

• Motherwort’s cardiac and hypotensive functional data rest on refined whole-extract preparations, and its uterotonic (“mother’s herb”) reputation is attributed to the herb’s alkaloids — the guanidine alkaloid leonurine (a L. japonicus marker) and the betaine stachydrine — not to leonuride ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. Do not read motherwort’s uterine or cardiovascular action onto this iridoid.
• The real isolate signal for ajugol is something different and more recent: anti-inflammatory and cytoprotective activity in models of asthma, fatty liver, osteoarthritis and neuroinflammation, driven largely from Rehmannia- and Leonurus-sourced material ^{2,3,4,5Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →Reference 5Han X et al. · 2025Systems pharmacology identifies ajugol-mediated NF-κB/caspase-3 inhibition and isoacteoside-driven p62/mTOR-mediated autophagy as key mechanisms of Rehmanniae Radix and its processed form in Alzheimer’s treatmentView study →}.

So the accurate one-line reading is: leonuride is a genuine, chemically-defined motherwort/Rehmannia iridoid with a coherent preclinical anti-inflammatory/pro-autophagy dossier — but its headline “motherwort” actions (uterine, cardiovascular) are the whole herb’s, and no human has been given the pure molecule.

What It's Used For

The evidence is entirely preclinical but unusually coherent for a compound this obscure: four independent rodent/cell studies since 2021, each in a different disease model, keep landing on the same two levers — TFEB-mediated autophagy and NF-κB/inflammasome suppression.

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. Every application here rests on a single isolate study in rodents/cells, so scores stay modest by design.

01Anti-inflammatory / airway (asthma)Shaky34%One isolate mouse study: ↓type-2 cytokines, remodeling, TGF-β1 ^{2Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →}

02Metabolic / hepatic steatosis (NAFLD)Shaky30%Isolate mouse + hepatocyte: TFEB lipophagy restores autophagic flux ^{3Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →}

03Cartilage / osteoarthritisShaky26%Isolate mouse + chondrocyte: TFEB autophagy relieves ER stress ^{4Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →}

04Neuroprotective / neuroinflammationShaky22%Systems-pharmacology + model: NF-κB/caspase-3 within Rehmannia network ^{5Reference 5Han X et al. · 2025Systems pharmacology identifies ajugol-mediated NF-κB/caspase-3 inhibition and isoacteoside-driven p62/mTOR-mediated autophagy as key mechanisms of Rehmanniae Radix and its processed form in Alzheimer’s treatmentView study →}

Mechanisms

The load-bearing observation is convergence: two of the four models (liver, cartilage) run through TFEB-driven autophagy, and two (asthma, brain) through NF-κB/inflammasome suppression — a single antioxidant/anti-inflammatory, pro-autophagy theme surfacing as organ protection in different tissues, rather than four unrelated activities. It is a coherent story, but built entirely from single studies.

Pharmacokinetics

Leonuride behaves as a typical poorly-absorbed iridoid glucoside. A validated rat LC-ESI-MS/MS study measured ajugol alongside aucubin and catalpol, finding measurable plasma exposure and wide tissue distribution; notably, aucubin and catalpol reached brain tissue, consistent with limited central penetration for this class ^{7Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →}. The iridoid-class reviews describe the same pattern generally — hydrophilic glucosides with low oral bioavailability, extensive gut/hepatic first-pass handling and β-glucosidase-mediated cleavage to an aglycone ^{6Reference 6Wang C et al. · 2020Iridoids: research advances in their phytochemistry, biological activities, and pharmacokineticsView study →}. A precise oral-bioavailability figure and half-life for ajugol specifically are not well documented, which is exactly why the in-vitro (µM) and high-dose rodent (mg/kg) potencies above should be read cautiously.

Clinical Trials

There are no clinical trials of isolated leonuride/ajugol — it has never been administered to humans as a therapeutic isolate. Human exposure is incidental, through whole motherwort and rehmannia preparations, whose own clinical footprints belong to the whole herb, not this iridoid ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}.

Last checked: July 2026.

Isolate vs. Plant Studies

The split is clean and, unusually, favours the isolate on attribution. The anti-inflammatory / pro-autophagy dossier — asthma, NAFLD, osteoarthritis, Alzheimer-model neuroinflammation — was generated with ajugol as the isolated compound in rodents and cell lines ^{2,3,4Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →}, which means those are leonuride’s own effects, not a plant extract’s borrowed credit. (The neuro study is a partial exception: ajugol is credited within a Rehmannia network-pharmacology model rather than a stand-alone trial ^{5Reference 5Han X et al. · 2025Systems pharmacology identifies ajugol-mediated NF-κB/caspase-3 inhibition and isoacteoside-driven p62/mTOR-mediated autophagy as key mechanisms of Rehmanniae Radix and its processed form in Alzheimer’s treatmentView study →}.) The weakness is translational, not attributional — poor oral bioavailability and the reactive-aglycone chemistry of iridoid glucosides mean isolate potency does not transfer cleanly to an oral human dose ^{6,7Reference 6Wang C et al. · 2020Iridoids: research advances in their phytochemistry, biological activities, and pharmacokineticsView study →Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →}. Conversely, motherwort’s traditional and clinical reputation (calming, mildly hypotensive, uterotonic) is a whole-herb phenomenon attributed to its alkaloids and refined extracts — leonuride contributes bitterness and is a marker, but the herb’s headline actions are not its ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. Read leonuride’s own file as the preclinical anti-inflammatory/autophagy story; its presence in motherwort says nothing about the isolate’s cardiovascular or uterine activity.

Prevalence in Nature

Leonuride is a widely distributed Lamiales iridoid glucoside. It is a characteristic iridoid of motherwort — both European Leonurus cardiaca (Ph.Eur. species) and the TCM L. japonicus / Yi Mu Cao — where it belongs to the herb’s bitter iridoid fraction ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. It is also one of the more abundant iridoid glucosides in the roots of Rehmannia glutinosa (di huang), where it co-occurs with catalpol and other iridoids and is the source material for most of the pharmacology above ^{7,8Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →Reference 8Liu YF et al. · 2024Four new iridoid glycosides from the roots of Rehmannia glutinosaView study →}. Further occurrence spans the genus Ajuga (bugleweed), from which the synonym ajugol derives. Biosynthetically it is a member of the iridoid pathway (geraniol → iridodial → iridoid glucoside) shared across chemically-defended Lamiales lineages. Absolute content is rarely quantified as % dry weight and varies widely with species, plant part (root in Rehmannia, aerial parts in Leonurus) and provenance, so no reliable cross-source concentration ranking exists — a gap tracked for a later pass rather than asserted here.

Discovery & Synthesis

Leonuride entered the literature as an iridoid glucoside characterised from Lamiales plants, and the name ajugol was coined for the molecule after the genus Ajuga. Its structure was subsequently revised (in tandem with the closely related iridoid myoporoside), a reminder that the early 13C-NMR assignments of these bitter glucosides needed correction — a common episode in mid-to-late-20th-century iridoid chemistry. Total synthesis of leonuride/ajugol is not well documented and is not the practical route to the compound: like other abundant iridoid glucosides, research supply is by extraction from rich natural sources — chiefly Rehmannia glutinosa root, and Leonurus and Ajuga aerial parts — because the molecule is plentiful in nature and its polar, glucoside chemistry makes isolation more attractive than synthesis.

Patents: not yet researched.

Toxicity & Safety

Leonuride reads as a low-toxicity, food-and-medicine-adjacent iridoid: it is a natural constituent of long-used herbs (motherwort, Rehmannia), and the rodent efficacy studies report no acute toxicity signal at the doses used ^{2,3,4Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →}. The caveats are evidentiary and chemical rather than observed harms — there is no dedicated isolate toxicology package, and the whole-herb safety questions around its source plants are not this molecule’s to answer.

Safety at a Glance

✅ Low / no toxicity

• A constituent of long-used herbs. Present in motherwort and Rehmannia, both with extensive traditional use; no acute toxicity signal at the doses used in rodent efficacy studies ^{2,3,4Reference 2Yi L et al. · 2022AnimalA novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic miceView study →Reference 3Zhang H et al. · 2021Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver diseaseView study →Reference 4Wu J et al. · 2023AnimalAjugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse modelView study →}.
• Real-world exposure is small and indirect. Intake occurs only through whole herbs, not as an isolate; poor oral bioavailability further limits systemic exposure ^{6,7Reference 6Wang C et al. · 2020Iridoids: research advances in their phytochemistry, biological activities, and pharmacokineticsView study →Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →}.
• Motherwort’s cautions are not leonuride’s. The herb’s uterine/cardiovascular actions — and any pregnancy caution around motherwort — belong to the whole herb and its alkaloids, and are decided on the herb page, not here ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}.
• No comprehensive isolate toxicology. No definitive LD50, genotoxicity, reproductive or repeat-dose package for pure leonuride; interactions have not been characterised.

Reproductive note (prose only). No dedicated reproductive-toxicity dataset exists for isolated leonuride. Motherwort itself is traditionally cautioned in pregnancy because of its whole-herb uterotonic reputation, which is attributed to the herb’s alkaloids (leonurine, stachydrine) rather than to this iridoid ^{1Reference 1Wojtyniak K et al. · 2013ReviewLeonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacologyView study →}. Any pregnancy or lactation decision therefore belongs to the motherwort or Rehmannia herb page, where intake is decided — not to this molecule-level page.

Dosage

There is no established or recommended human dose for isolated leonuride — it has never been given to people as an isolate for therapy. The only human-relevant framing is indirect, through whole motherwort or rehmannia preparations, whose dosing is the herb’s, not the molecule’s.

These are preclinical research doses, not recommendations, and they do not translate to humans given the poor oral bioavailability of iridoid glucosides ^{6,7Reference 6Wang C et al. · 2020Iridoids: research advances in their phytochemistry, biological activities, and pharmacokineticsView study →Reference 7Xue B et al. · 2015AnimalPharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assayView study →}. These are doses studied in research and are not a personal recommendation.

References

1. Wojtyniak K, Szymański M, Matławska I. (2013). Leonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacology. Phytotherapy Research. https://pubmed.ncbi.nlm.nih.gov/23042598/
2. Yi L, et al. (2022). A novel iridoid glycoside leonuride (ajugol) attenuates airway inflammation and remodeling through inhibiting type-2 high cytokine/chemokine activity in OVA-induced asthmatic mice. Phytomedicine. https://pubmed.ncbi.nlm.nih.gov/35905568/
3. Zhang H, et al. (2021). Ajugol enhances TFEB-mediated lysosome biogenesis and lipophagy to alleviate non-alcoholic fatty liver disease. Pharmacological Research. https://pubmed.ncbi.nlm.nih.gov/34732369/
4. Wu J, et al. (2023). Ajugol’s upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse model. Chinese Medicine. https://pubmed.ncbi.nlm.nih.gov/37679844/
5. Han X, et al. (2025). Systems pharmacology identifies ajugol-mediated NF-κB/caspase-3 inhibition and isoacteoside-driven p62/mTOR-mediated autophagy as key mechanisms of Rehmanniae Radix and its processed form in Alzheimer’s treatment. Frontiers in Pharmacology. https://pubmed.ncbi.nlm.nih.gov/40949132/
6. Wang C, et al. (2020). Iridoids: research advances in their phytochemistry, biological activities, and pharmacokinetics. Molecules. https://pubmed.ncbi.nlm.nih.gov/31936853/
7. Xue B, et al. (2015). Pharmacokinetics and tissue distribution of aucubin, ajugol and catalpol in rats using a validated simultaneous LC-ESI-MS/MS assay. Journal of Chromatography B. https://pubmed.ncbi.nlm.nih.gov/26342167/
8. Liu YF, et al. (2024). Four new iridoid glycosides from the roots of Rehmannia glutinosa. Journal of Asian Natural Products Research. https://pubmed.ncbi.nlm.nih.gov/37162445/

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