Epirosmanol

Epirosmanol at a Glance

Epirosmanol is a phenolic abietane diterpene — C₂₀H₂₆O₅, MW 346.4, CAS 93380-12-2, PubChem CID 9884612 — found in the leaves of rosemary and sage. It is not a primary plant product. It sits two oxidation steps downstream of carnosic acid: carnosic acid oxidises to carnosol, and carnosol opens onward to rosmanol, epirosmanol, isorosmanol and rosmadial ^{1,6Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →Reference 6Marrero JG et al. · 2002Semisynthesis of rosmanol and its derivativesView study →}. Where a rosemary or sage preparation lands on that cascade is a function of extraction solvent, heat, light and storage age rather than of the plant.

Two things should frame everything below.

First, this molecule has never been the subject of a study. PubMed indexes 18 records that mention epirosmanol; zero of them carry it in the title. Every one is either a phytochemical inventory, an assay panel in which epirosmanol was one line among six or nine, or a paper about a different compound entirely. There is no review of it, no pharmacokinetic study, no animal experiment and no human data.

Second, its most-repeated claim is not a claim about the molecule. Epirosmanol is widely listed as an anti-Helicobacter pylori constituent of sage. That attribution traces to a single 2023 paper in which the anti-H. pylori activity belonged to a whole ethanolic extract, and the in-silico work singled out carnosic acid, not epirosmanol ^{10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →}. The molecule was detected, not tested. That distinction is the point.

The Anti-Helicobacter Claim, Checked

Alomar and colleagues (2023) profiled Salvia officinalis by LC-MS and GC-MS, then tested the total ethanolic extract (TES) and the essential oil against H. pylori and in a COX-2 inhibition assay. Epirosmanol was the second-largest LC-MS peak in the extract at 20.65%, behind carnosic acid at 37.66% and ahead of 12-O-methyl carnosol (6.15%) and carnosol (3.3%) ^{10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →}.

What was measured, and on what:

Entity	Assay	Result
Total ethanolic extract	Anti-H. pylori micro-well dilution	3.9 µg/mL (clarithromycin 0.43 µg/mL)
Essential oil	Anti-H. pylori micro-well dilution	15.63 µg/mL
Total ethanolic extract	COX-2 inhibition	IC₅₀ 1.7 ± 0.27 µg/mL (celecoxib comparator)
Essential oil	COX-2 inhibition	IC₅₀ 5.3 ± 0.62 µg/mL
Carnosic acid	Molecular docking, H. pylori target	Best binding energy, −46.6769 kcal/mol
Epirosmanol	—	Not isolated. Not assayed. Not the docking winner.

So the honest statement is: epirosmanol is an abundant LC-MS peak in an ethanolic sage extract that inhibits H. pylori at 3.9 µg/mL, and the paper’s own computational analysis attributes that activity to carnosic acid ^{10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →}. Nothing in that study supports “epirosmanol is antibacterial.” It has never been tested against H. pylori as an isolate, at any concentration, by anyone.

One further caution about the 20.65%: it is a relative LC-MS peak area, not a mass fraction. Different diterpenes ionise with wildly different efficiency in negative-mode ESI, so a peak-area percentage is not a concentration and should never be read as one.

The Sage Essential-Oil Figure That Cannot Be Right

A second, larger attribution problem is worth flagging because it is actively propagating.

A 2024 study of essential oils against cheese-derived staphylococci reports that the main component of sage essential oil was epirosmanol at 26.25% ^{11Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →}. A 2025 modelling paper from the same institution reuses that composition and names epirosmanol, carvacrol, limonene and thymol as the compounds driving sage’s antimicrobial effect in cheese, on the basis of docking scores and machine-learning regression ^{12Reference 12Vukić D et al. · 2025Application of predictive modeling and molecular simulations to elucidate the mechanisms underlying the antimicrobial activity of sage (Salvia officinalis L.) components in fresh cheese productionView study →}; its composition data trace back to the group’s own 2023 analysis ^{13Reference 13Vukić V et al. · 2023Antimicrobial potential of kombucha fresh cheese with the addition of sage (Salvia officinalis L.) and its preparationsView study →}.

This is almost certainly a gas-chromatography misassignment, and it should not be cited as an occurrence figure:

• Epirosmanol is a trihydroxy diterpene lactone (MW 346, five oxygens, three free phenolic/alcoholic hydroxyls). It is not volatile and is not steam-distillable — the property that defines an essential-oil component.
• Sage essential oil is one of the best-characterised oils in the materia medica. Across hundreds of published analyses it is dominated by α-thujone, camphor and 1,8-cineole; no independent laboratory has ever reported a diterpene as its major peak.
• The same analyses place carvacrol and thymol among the sage-oil actives — those are the marker phenols of oregano and thyme, not of Salvia officinalis.

The likeliest explanation is a mass-spectral library match to a co-eluting or thermally degraded peak. The practical consequence is that a computational paper’s conclusions ^{12Reference 12Vukić D et al. · 2025Application of predictive modeling and molecular simulations to elucidate the mechanisms underlying the antimicrobial activity of sage (Salvia officinalis L.) components in fresh cheese productionView study →} rest on an input composition that is chemically implausible, and any downstream “epirosmanol is antimicrobial” claim inherits that error. Note also that PubChem’s own synonym list for epirosmanol (CID 9884612) contains the entry “Rosmanol [M+H]+” — a mass-spectral alias for a different molecule, which is the same class of error at the database level ^{23Reference 23PubChem Compound Summary: EpirosmanolNational Library of MedicineView study →}.

Epirosmanol, Rosmanol & Isorosmanol

These three names are used interchangeably in secondary sources far more often than the chemistry allows. They are not interchangeable, and one of the three relationships is not the one usually assumed.

Compound	Structure	Relationship to epirosmanol
Rosmanol	7α,11,12-trihydroxy-6,10-(epoxymethano)abieta-8,11,13-trien-20-one	C-7 epimer — same connectivity, opposite configuration at C-7
Epirosmanol	7β,11,12-trihydroxy-6,10-(epoxymethano)abieta-8,11,13-trien-20-one	—
Isorosmanol	6α,11,12-trihydroxy-7,10-(epoxymethano)abieta-8,11,13-trien-20-one	Constitutional isomer, not an epimer — the lactone bridges C-7→C-20 instead of C-6→C-20

All three are C₂₀H₂₆O₅, MW 346.4, and all three were defined in the same 1984 Nakatani and Inatani paper — which named epirosmanol and isorosmanol and simultaneously corrected the published structure of rosmanol itself ^{1Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →}. The “epi-” prefix was therefore assigned relative to a structure being revised in the same breath, which is part of why the older literature is inconsistent.

Does the distinction matter pharmacologically? Yes, and it has been measured. In the only study to test the epimers side by side under identical conditions, Fischedick and colleagues found epirosmanol a weaker activator of the antioxidant response element than rosmanol and concluded explicitly that “the stereochemistry of the hydroxyl group at C-7 is important” ^{7Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →}. Isorosmanol, meanwhile, is the member of the trio with the most independent pharmacology — it, and not epirosmanol, was the compound flagged as a melanin-synthesis and acetylcholinesterase inhibitor in a sage diterpene panel that contained both ^{8Reference 8Sallam A et al. · 2016Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalisView study →}.

Practical rule for reading this literature: where a source says “rosmanol” without a stereodescriptor and without an isolation reference, treat the identity as unresolved.

The Whole Literature, Listed

Eighteen PubMed records is small enough to inventory. Europe PMC’s full-text index returns ~190 mentions, but those are overwhelmingly supplementary-table entries in phytochemical surveys rather than studies of the compound.

Year	Study	What it did with epirosmanol	Ref
1984	Nakatani & Inatani	First isolation from rosemary; structure; antioxidant activity in lard and linoleic acid	1Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →
1995	Haraguchi et al.	Isolated from rosemary by bioassay-guided fractionation; superoxide and lipid-peroxidation inhibition	2Reference 2Haraguchi H et al. · 1995Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalisView study →
2001	Zeng et al.	Isolate; inhibition of human LDL oxidation	3Reference 3Zeng HH et al. · 2001Antioxidant properties of phenolic diterpenes from Rosmarinus officinalisView study →
2001	Miura et al.	Identified among 15 knowns in a sage apianane-terpenoid paper	5Reference 5Miura K et al. · 2001Apianane terpenoids from Salvia officinalisView study →
2002	Miura et al.	Isolate; oil-stability-index antioxidant assay vs α-tocopherol	4Reference 4Miura K et al. · 2002Antioxidant activity of chemical components from sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.) measured by the oil stability index methodView study →
2002	Marrero et al.	Semisynthesis from carnosol	6Reference 6Marrero JG et al. · 2002Semisynthesis of rosmanol and its derivativesView study →
2003	Santos-Gomes et al.	Detected in sage callus culture, absent from cell suspensions	16Reference 16Santos-Gomes PC et al. · 2003Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.)View study →
2005	Pukalskas et al.	”Epirosmanol methyl ether” tentatively identified in commercial rosemary extract	18Reference 18Pukalskas A et al. · 2005Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extractsView study →
2010	Christensen et al.	An epirosmanol ester of 12-O-methyl carnosic acid isolated; PPARγ screen	17Reference 17Christensen KB et al. · 2010Activation of the nuclear receptor PPARγ by metabolites isolated from sage (Salvia officinalis L.)View study →
2012	Tabata et al.	Among five phenolic diterpenes from Hyptis incana vs neuroblastoma cells	19Reference 19Tabata K et al. · 2012Phenolic diterpenes derived from Hyptis incana induce apoptosis and G2/M arrest of neuroblastoma cellsView study →
2013	Fischedick et al.	Isolate; Nrf2/ARE structure–activity panel of seven sage diterpenes	7Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →
2014	Zhang et al.	Isolated as a known compound from Rosmarinus officinalis aerial parts	15Reference 15Zhang Y et al. · 2014New terpenoid glycosides obtained from Rosmarinus officinalis L. aerial partsView study →
2016	Sallam et al.	Isolate; tested and not among the actives for AChE or melanin inhibition	8Reference 8Sallam A et al. · 2016Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalisView study →
2019	Zhang et al.	”Epirosmanol methyl ether” flagged in a rosemary vasorelaxant screen	21Reference 21Zhang J et al. · 2019Screening active ingredients of rosemary based on spectrum-effect relationships between UPLC fingerprint and vasorelaxant activity using three chemometricsView study →
2019	Arriola et al.	Untargeted metabolomics annotation in a stevia encapsulation study — almost certainly a false positive	22Reference 22Arriola NDA et al. · 2019Encapsulation of Stevia rebaudiana Bertoni aqueous crude extracts by ionic gelation — effects of alginate blends and gelling solutions on the polyphenolic profileView study →
2021	Llurba Montesino et al.	Purified; tested against Trypanosoma brucei rhodesiense with cytotoxicity control	9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →
2023	Alomar et al.	LC-MS peak in an anti-H. pylori sage extract; not assayed	10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →
2024	Nikolić et al.	Reported as 26.25% of sage essential oil — implausible (see above)	11Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →
2025	Revuru et al.	Upregulated in SmERF6-overexpressing sage; biosynthesis	14Reference 14Revuru B et al. · 2025SmERF6 promotes the expression of terpenoid pathway in Salvia officinalis and improves the production of high-value abietane diterpenes, carnosol and carnosic acidView study →
2025	Vukić et al.	In-silico/machine-learning antimicrobial model built on 11Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →/13Reference 13Vukić V et al. · 2023Antimicrobial potential of kombucha fresh cheese with the addition of sage (Salvia officinalis L.) and its preparationsView study →	12Reference 12Vukić D et al. · 2025Application of predictive modeling and molecular simulations to elucidate the mechanisms underlying the antimicrobial activity of sage (Salvia officinalis L.) components in fresh cheese productionView study →

Four of those are the isolate pharmacology it is built on ^{2,3,7,9Reference 2Haraguchi H et al. · 1995Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalisView study →Reference 3Zeng HH et al. · 2001Antioxidant properties of phenolic diterpenes from Rosmarinus officinalisView study →Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →}; the rest are chemistry, detection, modelling or error.

What It's Used For

Four studies have put purified epirosmanol into a biological assay. The results are consistent and unremarkable: it is a competent lipophilic antioxidant of the same order as its siblings, with no target of its own.

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. With no animal or human study anywhere in this literature, every score is capped low by design. Each application links to its write-up.

01Antioxidant & Lipid ProtectionShaky35%Four independent isolate studies, cell-free and ex-vivo ^{1,2,3,4Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →Reference 2Haraguchi H et al. · 1995Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalisView study →Reference 3Zeng HH et al. · 2001Antioxidant properties of phenolic diterpenes from Rosmarinus officinalisView study →Reference 4Miura K et al. · 2002Antioxidant activity of chemical components from sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.) measured by the oil stability index methodView study →}

02Nrf2 / ARE ActivationShaky18%One isolate SAR panel; weaker than its own epimer ^{7Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →}

03AntitrypanosomalShaky15%One purified-compound assay, selectivity index 1.6 ^{9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →}

04AntimicrobialShaky8%Extract-level and in-silico only; no isolate ever tested ^{10,11,12Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →Reference 12Vukić D et al. · 2025Application of predictive modeling and molecular simulations to elucidate the mechanisms underlying the antimicrobial activity of sage (Salvia officinalis L.) components in fresh cheese productionView study →}

05Cholinesterase & MelaninShaky5%Tested as an isolate and reported inactive ^{8Reference 8Sallam A et al. · 2016Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalisView study →}

Mechanisms

Pharmacokinetics

There is no pharmacokinetic study of epirosmanol — no absorption figure, no oral bioavailability, no plasma concentration, no half-life, in any species. epirosmanol AND pharmacokinetics returns zero PubMed records.

One indirect measurement exists. A 2025 biorefinery study of Salvia officinalis ran a PAMPA-BBB permeability model on its extracts and tracked individual compounds by HPLC-QTOF-MS peak area across the donor, permeable and non-permeable fractions. Epirosmanol was one of the compounds of which “around 50%” crossed the artificial barrier — better than caffeic acid (~10%) and better than carnosol, carnosic acid and methyl carnosate, which showed minimal permeability ^{20Reference 20Romano E et al. · 2025Sequential obtention of blood-brain barrier-permeable non-polar and polar compounds from Salvia officinalis L. and Eucalyptus globulus Labill. with neuroprotective purposesView study →}.

That is worth exactly what it is: a peak-area observation in an artificial-membrane model, not a measured permeability coefficient and not an in-vivo result. What it suggests is chemically sensible — epirosmanol is a smaller, lactonised, somewhat more polar molecule than its carnosic acid parent, which is the direction that helps passive membrane transit. It does not establish that any amount of epirosmanol survives ingestion, and no study has looked.

Clinical Trials

None. There are no clinical trials of epirosmanol — a ClinicalTrials.gov search returns 0 studies under that name (checked August 2026). Human exposure is entirely incidental, through culinary rosemary and sage and through rosemary antioxidant extracts.

Last checked: August 2026.

Isolate vs. Plant

The boundary is unusually easy to draw here, because there is so little on either side.

Genuine isolate evidence: four studies ^{2,3,4,7Reference 2Haraguchi H et al. · 1995Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalisView study →Reference 3Zeng HH et al. · 2001Antioxidant properties of phenolic diterpenes from Rosmarinus officinalisView study →Reference 4Miura K et al. · 2002Antioxidant activity of chemical components from sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.) measured by the oil stability index methodView study →Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →} plus the 1984 isolation paper ^{1Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →} and the 2021 trypanosome panel ^{9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →}. In all of them epirosmanol was purified before testing, and in all of them it was one entry in a comparative table.

Plant-level claims that get mis-credited to it: the anti-H. pylori and COX-2 results, which belong to a whole sage ethanolic extract ^{10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →}; the antistaphylococcal results, which belong to a sage essential oil whose composition is doubtful ^{11Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →}; and the rosemary vasorelaxant work, in which the compound flagged was epirosmanol methyl ether — a different molecule — and the two compounds actually verified pharmacologically were carnosic acid and carnosol ^{21Reference 21Zhang J et al. · 2019Screening active ingredients of rosemary based on spectrum-effect relationships between UPLC fingerprint and vasorelaxant activity using three chemometricsView study →}.

Derivatives that are not epirosmanol. Three distinct entities in this literature carry the name inside theirs and must not be conflated with the parent: epirosmanol methyl ether ^{18,21Reference 18Pukalskas A et al. · 2005Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extractsView study →Reference 21Zhang J et al. · 2019Screening active ingredients of rosemary based on spectrum-effect relationships between UPLC fingerprint and vasorelaxant activity using three chemometricsView study →}, the epirosmanol ester of 12-O-methyl carnosic acid ^{17Reference 17Christensen KB et al. · 2010Activation of the nuclear receptor PPARγ by metabolites isolated from sage (Salvia officinalis L.)View study →}, and epiisorosmanol ^{18Reference 18Pukalskas A et al. · 2005Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extractsView study →}. Each was reported in a different study, and none of their results transfers.

The transfer in the other direction fails too. Nothing here supports a claim about rosemary or sage as herbs. Epirosmanol is a minor member of a diterpene fraction whose recognised actives — the compounds that carry the food-preservative function and most of the pharmacology — are carnosic acid and carnosol.

Prevalence in Nature

Epirosmanol is a Lamiaceae compound, and within the family it is essentially a Salvia compound. Its distribution follows carnosic acid’s, because it is made from it.

Source	Part	Basis
Rosemary (Salvia rosmarinus, syn. Rosmarinus officinalis)	Leaves, aerial parts	Type source — first isolation 1984 1Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →; re-isolated by bioassay-guided fractionation 2Reference 2Haraguchi H et al. · 1995Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalisView study → and as a known compound in a terpenoid-glycoside study 15Reference 15Zhang Y et al. · 2014New terpenoid glycosides obtained from Rosmarinus officinalis L. aerial partsView study →
Sage (Salvia officinalis)	Leaves, aerial parts	Isolated repeatedly from methanolic, dichloromethane and ethanolic extracts 5,7,8,17Reference 5Miura K et al. · 2001Apianane terpenoids from Salvia officinalisView study →Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →Reference 8Sallam A et al. · 2016Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalisView study →Reference 17Christensen KB et al. · 2010Activation of the nuclear receptor PPARγ by metabolites isolated from sage (Salvia officinalis L.)View study →; produced by sage callus culture but not by cell suspensions 16Reference 16Santos-Gomes PC et al. · 2003Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.)View study →
Hyptis incana	Aerial parts	Single report, among five phenolic diterpenes tested on neuroblastoma cells 19Reference 19Tabata K et al. · 2012Phenolic diterpenes derived from Hyptis incana induce apoptosis and G2/M arrest of neuroblastoma cellsView study →

No concentration figure exists. Not a mg/g, not a % dry weight, for any source. The two percentages in circulation are a relative LC-MS peak area (20.65% of an ethanolic sage extract ^{10Reference 10Alomar HA et al. · 2023In vitroAnti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studiesView study →}) and an implausible GC figure (26.25% of sage essential oil ^{11Reference 11Nikolić I et al. · 2024Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese modelView study →}); neither is a concentration.

A note on the Hyptis attribution. It is the only occurrence claim outside Salvia, and it deserves a caveat: the compound tested alongside epirosmanol with the highest efficacy in that study was 7-ethoxyrosmanol ^{19Reference 19Tabata K et al. · 2012Phenolic diterpenes derived from Hyptis incana induce apoptosis and G2/M arrest of neuroblastoma cellsView study →}, and 7-alkoxyrosmanols form readily from carnosol on contact with the corresponding alcohol — a semisynthetic route published a decade earlier ^{6Reference 6Marrero JG et al. · 2002Semisynthesis of rosmanol and its derivativesView study →}. Whether that panel represents native Hyptis constituents or extraction artefacts is not resolvable from the abstract.

Two further sightings should be discounted. An untargeted-metabolomics annotation in a Stevia rebaudiana encapsulation study ^{22Reference 22Arriola NDA et al. · 2019Encapsulation of Stevia rebaudiana Bertoni aqueous crude extracts by ionic gelation — effects of alginate blends and gelling solutions on the polyphenolic profileView study →} is almost certainly a database false positive — stevia is an Asteraceae with no abietane-diterpene pathway. And the Salvia fruticosa co-mention that turns up in searches comes from a paper about S. officinalis that names S. fruticosa in passing ^{14Reference 14Revuru B et al. · 2025SmERF6 promotes the expression of terpenoid pathway in Salvia officinalis and improves the production of high-value abietane diterpenes, carnosol and carnosic acidView study →}, not from an occurrence report.

Its Role in Plants

Epirosmanol is a degradation product with a defensive function, and the distinction from a biosynthetic end-product matters for anyone trying to standardise a preparation.

Carnosic acid is the plant’s stored lipophilic antioxidant, concentrated in leaf chloroplasts, and it protects the photosynthetic apparatus by being sacrificially oxidised under light and oxidative stress ^{24Reference 24Birtić S et al. · 2015Carnosic acidView study →}. That oxidation is a cascade, not a single step: carnosic acid → carnosol → rosmanol, epirosmanol, isorosmanol, rosmadial and methyl carnosate ^{1,24Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →Reference 24Birtić S et al. · 2015Carnosic acidView study →}. Epirosmanol is therefore a marker of how much oxidative processing the tissue or the extract has undergone, and its level in a given batch of dried leaf or extract reflects harvest handling, drying temperature, solvent and storage age at least as much as it reflects the plant.

The pathway is transcriptionally tractable. Heterologous expression of the Salvia miltiorrhiza transcription factor SmERF6 in S. officinalis raised carnosol roughly two-fold and carnosic acid five-fold in infiltrated leaves, and significantly upregulated the carnosic acid derivatives — rosmanol, epirosmanol and methyl carnosic acid — along with the shared precursor ferruginol ^{14Reference 14Revuru B et al. · 2025SmERF6 promotes the expression of terpenoid pathway in Salvia officinalis and improves the production of high-value abietane diterpenes, carnosol and carnosic acidView study →}. Stable transgenic lines accumulated four-fold carnosol and three-fold carnosic acid. Tissue culture behaves differently: sage callus produced epirosmanol, while sage cell suspensions grown under the same hormone regimes did not, one of only two compounds in a twelve-phenolic panel to differ that way ^{16Reference 16Santos-Gomes PC et al. · 2003Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.)View study →}.

Discovery & Synthesis

Epirosmanol was isolated and named in 1984 by Nobuji Nakatani and Reiko Inatani at Osaka City University, from the leaves of rosemary, in a paper that reported two new antioxidative diterpenes — epirosmanol and isorosmanol — and revised the structure of rosmanol itself using NOE experiments and X-ray analysis ^{1Reference 1Nakatani N · 1984Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanolView study →}. Its structure was assigned as 7β,11,12-trihydroxy-6,10-(epoxymethano)abieta-8,11,13-trien-20-one. The name records the relationship: the epimer of rosmanol at C-7. In the same paper both new compounds were shown to be strongly antioxidative, roughly four times BHA and BHT in a lard system.

There is no total synthesis. There is a practical semisynthesis: Marrero, Andrés and Luis (2002) obtained rosmanol, rosmaquinone, 7-methoxyrosmanol, 7-ethoxyrosmanol, galdosol and epirosmanol by partial synthesis from carnosol, an abundant natural product, with physical and spectroscopic data identical to authentic natural samples ^{6Reference 6Marrero JG et al. · 2002Semisynthesis of rosmanol and its derivativesView study →}. Their explicit motivation was that these diterpenes occur in Salvia “in low quantities” — which is the clearest statement in the literature about epirosmanol’s natural abundance, even though it puts no number on it.

That route also has an analytical consequence: because these compounds form readily from carnosol under mild conditions in the presence of alcohols, 7-methoxy- and 7-ethoxyrosmanol recovered from methanolic or ethanolic plant extracts are suspect as solvent artefacts, and epirosmanol’s own levels in an extract are partly a function of processing ^{6Reference 6Marrero JG et al. · 2002Semisynthesis of rosmanol and its derivativesView study →}.

Commercially, epirosmanol is sold only as an analytical reference standard, in milligram quantities. It is not produced at scale and is not a component of any commercial product. Notably, the EU food additive extracts of rosemary (E 392) is specified and its maximum permitted levels expressed as the sum of carnosol and carnosic acid ^{25Reference 25EFSA Panel on Food Additives et al. · 2018Refined exposure assessment of extracts of rosemary (E 392) from its use as food additiveView study →} — epirosmanol, though it forms from both, is not part of that specification and is not measured in commerce.

Patents: not yet researched.

Toxicity & Safety

The honest verdict is not characterised, and the unknown grading is deliberate. There has never been a toxicology study of epirosmanol: no acute or repeat-dose study, no LD₅₀, no genotoxicity panel, no reproductive or developmental work, no interaction study, and no observation in an animal of any kind. epirosmanol AND toxicity returns a single PubMed record, and it is a cell-viability control inside an Nrf2 screen ^{7Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →}.

What can be said is narrow and comes from two cell assays. Epirosmanol is cytotoxic to a mammalian cell line at ~5 µg/mL (~14 µM) — rat L6 myoblasts, in the selectivity control of the trypanosome study ^{9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →}. In mouse primary cortical cultures it showed minimal toxicity across the range tested, in an experiment where carnosol was toxic at 50 µM and carnosaldehyde at 25 µM ^{7Reference 7Fischedick JT et al. · 2013Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathwayView study →}. Those two results are not contradictory — different cell types, different exposure windows — but the first is the one to hold onto, because it sits at the same concentration as the reported antioxidant activity.

Reproductive and developmental effects have never been investigated for this molecule. Decisions about rosemary or sage in pregnancy belong on those herb pages, where intake is actually decided, and turn on thujone and on whole-preparation data — not on this compound.

Safety at a Glance

❔ Toxicity unknown

• No adverse effect has ever been reported. It has also never been looked for — those are different statements, and the unknown grading reflects the second.
• Dietary exposure is long-standing and incidental. Anyone who cooks with rosemary or sage has been consuming small amounts of it indefinitely, with no signal attached.
• Cytotoxic to mammalian cells at ~14 µM in vitro ^{9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →}, which is inside the concentration range at which its antioxidant activity is reported ^{3Reference 3Zeng HH et al. · 2001Antioxidant properties of phenolic diterpenes from Rosmarinus officinalisView study →}. That is a reason not to treat a concentrated isolate as a benign supplement.
• Selectivity index of 1.6 in the only assay that measured one ^{9Reference 9Llurba Montesino N et al. · 2021Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesienseView study →} — the compound does not discriminate between a parasite and a host cell.
• No toxicology, no pharmacokinetics, no animal data, no human data. Every statement above is from a dish.
• No reproductive or developmental data exist. Nothing is known about use in pregnancy or breastfeeding.
• Drug interactions have never been assessed — no CYP, no P-glycoprotein, no transporter work of any kind for this molecule.

Dosage

There is no dose. Epirosmanol has never been administered to a person as an isolate, no animal dosing study exists to extrapolate from, and no pharmacokinetic study has established whether an oral dose would reach the bloodstream at all. Every published figure is an in-vitro concentration in the 3–30 µM range — the concentration at a cell or in a cuvette, not an intake.

Real-world exposure comes from rosemary and sage leaf and from rosemary antioxidant extracts, where epirosmanol is one unquantified minor diterpene in a fraction defined and regulated by carnosic acid and carnosol ^{25Reference 25EFSA Panel on Food Additives et al. · 2018Refined exposure assessment of extracts of rosemary (E 392) from its use as food additiveView study →}. The plant, not the molecule, is what anybody is actually taking. Nothing here is a recommendation.

References

1. Nakatani N, Inatani R (1984). Two antioxidative diterpenes from rosemary (Rosmarinus officinalis L.) and a revised structure for rosmanol. Agricultural and Biological Chemistry 48(8):2081–2085. https://doi.org/10.1271/bbb1961.48.2081
2. Haraguchi H, Saito T, Okamura N, Yagi A (1995). Inhibition of lipid peroxidation and superoxide generation by diterpenoids from Rosmarinus officinalis. Planta Medica. https://pubmed.ncbi.nlm.nih.gov/7480180/
3. Zeng HH, Tu PF, Zhou K, Wang H, Wang BH, Lu JF (2001). Antioxidant properties of phenolic diterpenes from Rosmarinus officinalis. Acta Pharmacologica Sinica. https://pubmed.ncbi.nlm.nih.gov/11749806/
4. Miura K, Kikuzaki H, Nakatani N (2002). Antioxidant activity of chemical components from sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.) measured by the oil stability index method. Journal of Agricultural and Food Chemistry. https://pubmed.ncbi.nlm.nih.gov/11902922/
5. Miura K, Kikuzaki H, Nakatani N (2001). Apianane terpenoids from Salvia officinalis. Phytochemistry. https://pubmed.ncbi.nlm.nih.gov/11738402/
6. Marrero JG, Andrés LS, Luis JG (2002). Semisynthesis of rosmanol and its derivatives. Easy access to abietatriene diterpenes isolated from the genus Salvia with biological activities. Journal of Natural Products. https://pubmed.ncbi.nlm.nih.gov/12141857/
7. Fischedick JT, Standiford M, Johnson DA, Johnson JA (2013). Structure activity relationship of phenolic diterpenes from Salvia officinalis as activators of the nuclear factor E2-related factor 2 pathway. Bioorganic & Medicinal Chemistry. https://pubmed.ncbi.nlm.nih.gov/23507152/
8. Sallam A, Mira A, Ashour A, Shimizu K (2016). Acetylcholine esterase inhibitors and melanin synthesis inhibitors from Salvia officinalis. Phytomedicine. https://pubmed.ncbi.nlm.nih.gov/27444345/
9. Llurba Montesino N, Kaiser M, Mäser P, Schmidt TJ (2021). Salvia officinalis L.: antitrypanosomal activity and active constituents against Trypanosoma brucei rhodesiense. Molecules. https://pubmed.ncbi.nlm.nih.gov/34072147/
10. Alomar HA, Elkady WM, Abdel-Aziz MM, Ibrahim TA, Fathallah N (2023). Anti-Helicobacter pylori and anti-inflammatory potential of Salvia officinalis metabolites: in vitro and in silico studies. Metabolites. https://pubmed.ncbi.nlm.nih.gov/36677061/
11. Nikolić I, Čabarkapa I, Pavlić B, Kravić S, Đilas M, Iličić M, Bulut S, Kocić-Tanackov S (2024). Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese — application of the oil mixture in a cheese model. International Journal of Food Microbiology. https://pubmed.ncbi.nlm.nih.gov/39182346/
12. Vukić D, Lončar B, Pezo L, Vukić V (2025). Application of predictive modeling and molecular simulations to elucidate the mechanisms underlying the antimicrobial activity of sage (Salvia officinalis L.) components in fresh cheese production. Foods. https://pubmed.ncbi.nlm.nih.gov/40646916/
13. Vukić V, Vukić D, Pavlić B, Iličić M, Kocić-Tanackov S, Kanurić K, Bjekić M, Zeković Z (2023). Antimicrobial potential of kombucha fresh cheese with the addition of sage (Salvia officinalis L.) and its preparations. Food & Function. https://pubmed.ncbi.nlm.nih.gov/36942549/
14. Revuru B, Thashanamoorthi G, Demiwal P, Sircar D, Ramalingam S (2025). SmERF6 promotes the expression of terpenoid pathway in Salvia officinalis and improves the production of high-value abietane diterpenes, carnosol and carnosic acid. Plant and Cell Physiology. https://pubmed.ncbi.nlm.nih.gov/39820705/
15. Zhang Y, Adelakun TA, Qu L, Li X, Li J, Han L, Wang T (2014). New terpenoid glycosides obtained from Rosmarinus officinalis L. aerial parts. Fitoterapia. https://pubmed.ncbi.nlm.nih.gov/25200369/
16. Santos-Gomes PC, Seabra RM, Andrade PB, Fernandes-Ferreira M (2003). Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.). Journal of Plant Physiology. https://pubmed.ncbi.nlm.nih.gov/14593803/
17. Christensen KB, Jørgensen M, Kotowska D, Petersen RK, Kristiansen K, Christensen LP (2010). Activation of the nuclear receptor PPARγ by metabolites isolated from sage (Salvia officinalis L.). Journal of Ethnopharmacology. https://pubmed.ncbi.nlm.nih.gov/20696231/
18. Pukalskas A, van Beek TA, de Waard P (2005). Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extracts. Journal of Chromatography A. https://pubmed.ncbi.nlm.nih.gov/15941042/
19. Tabata K, Kim M, Makino M, Satoh M, Satoh Y, Suzuki T (2012). Phenolic diterpenes derived from Hyptis incana induce apoptosis and G2/M arrest of neuroblastoma cells. Anticancer Research. https://pubmed.ncbi.nlm.nih.gov/23155243/
20. Romano E, Domínguez-Rodríguez G, Mannina L, Cifuentes A, Ibáñez E (2025). Sequential obtention of blood-brain barrier-permeable non-polar and polar compounds from Salvia officinalis L. and Eucalyptus globulus Labill. with neuroprotective purposes. International Journal of Molecular Sciences. https://pubmed.ncbi.nlm.nih.gov/39859317/
21. Zhang J, Chen T, Li K, Xu H, Liang R, Wang W, Li H, Shao A, Yang B (2019). Screening active ingredients of rosemary based on spectrum-effect relationships between UPLC fingerprint and vasorelaxant activity using three chemometrics. Journal of Chromatography B. https://pubmed.ncbi.nlm.nih.gov/31785534/
22. Arriola NDA, Chater PI, Wilcox M, Lucini L, Rocchetti G, Dalmina M, Pearson JP, de Mello Castanho Amboni RD (2019). Encapsulation of Stevia rebaudiana Bertoni aqueous crude extracts by ionic gelation — effects of alginate blends and gelling solutions on the polyphenolic profile. Food Chemistry. https://pubmed.ncbi.nlm.nih.gov/30724178/
23. PubChem Compound Summary: Epirosmanol, CID 9884612. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/9884612
24. Birtić S, Dussort P, Pierre FX, Bily AC, Roller M (2015). Carnosic acid. Phytochemistry 115:9–19. https://pubmed.ncbi.nlm.nih.gov/25639596/
25. EFSA Panel on Food Additives and Nutrient Sources added to Food (2018). Refined exposure assessment of extracts of rosemary (E 392) from its use as food additive. EFSA Journal 16(3):5373. https://doi.org/10.2903/j.efsa.2018.5373

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