Nepetalic Acid

Nepetalic Acid at a Glance

Nepetalic acid is a small iridoid monoterpene from catnip (Nepeta cataria). Unlike the iridoid glycosides — such as aucubin, catalpol or asperuloside — it is non-glycosidic: a free monoterpenoid carboxylic acid, not a sugar-bound one. It occurs in the plant as a co-marker of the volatile oil alongside catnip’s dominant iridoid, nepetalactone, and is chemically the ring-opened acid relative of that lactone.

Its most important honest point comes first: catnip’s famous bioactivity is nepetalactone’s, not nepetalic acid’s. The cat-attractant “euphoria” response and the strong mosquito/tick repellency both belong to the lactone ^{4Reference 4Melo N et al. · 2021The irritant receptor TRPA1 mediates the mosquito repellent effect of catnipView study →}; nepetalic acid’s own documented pharmacology is minimal — a single old animal study in which it prolonged barbiturate sleeping time in mice ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →}. Treat it primarily as a chemistry and quality-control marker of catnip oil rather than as a bioactive in its own right.

Nepetalic Acid vs. Nepetalactone

This is the section the molecule exists for, and the distinction is easy to blur because the two compounds are close chemical relatives that co-occur in the same oil.

Nepetalactone is the lactone — a cyclic ester, and the defining iridoid of catnip (roughly 40–98% of the essential oil, chemotype-variable). Nepetalic acid is the corresponding acid — the ring-opened form, produced when the lactone is hydrolysed ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}. In the classic 1941 fractionation of catnip oil, the two came out together: nepetalactone ~40–50%, nepetalic acid ~33%, with a smaller neutral fraction ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}. Nepetalic acid also functions as a synthetic intermediate, since it interconverts with the lactone.

The honest note is that the pharmacology sits almost entirely with the lactone, and must not be borrowed onto the acid:

Cat-attractant response — the sniff-lick-roll euphoria is triggered by volatile nepetalactone via the feline olfactory route. Nepetalic acid is not the established cat attractant.
Insect / tick repellency — catnip’s repellent effect is driven by nepetalactone acting as an agonist of the insect irritant receptor TRPA1 (and, notably, it does not activate the human receptor) ^{4Reference 4Melo N et al. · 2021The irritant receptor TRPA1 mediates the mosquito repellent effect of catnipView study →}. This is nepetalactone’s mechanism, not a demonstrated property of nepetalic acid.
Nepetalic acid’s own documented activity is minimal — see below. State it plainly: isolate data for nepetalic acid are thin.

What It's Used For

There is very little isolate pharmacology for nepetalic acid specifically. Essentially all of the “catnip does X” evidence rests on the whole essential oil or on nepetalactone; the acid appears in that literature as a co-constituent that is rarely tested on its own.

One historical animal datapoint:in a 1978 study, nepetalic acid (62.5 mg/kg) — like catnip oil itself — significantly increased hexobarbital sleeping time in mice, a sedative/barbiturate-potentiating signal ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →}.

A contradicted, herb-level picture:that lone sedative signal is undercut by a later study in which whole catnip produced an amphetamine-like stimulant profile (increased locomotion and rearing, decreased pentobarbital sleeping time) in mice ^{3Reference 3Massoco CO et al. · 1995AnimalBehavioral effects of acute and long-term administration of catnip (Nepeta cataria) in miceView study →} — but that study used the whole herb, not isolated nepetalic acid.

The honest headline:nepetalic acid has no established human use, no clinical trials, and no clean mechanism of its own. Its documented role is as a chemistry/quality-control marker of catnip oil; catnip’s real bioactivities belong to nepetalactone ^{4Reference 4Melo N et al. · 2021The irritant receptor TRPA1 mediates the mosquito repellent effect of catnipView study →}.

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. For nepetalic acid there is essentially one thin, contradicted animal datapoint, so the single score stays very low by design.

Mechanisms

No molecular target or pathway is established for nepetalic acid itself. The barbiturate-potentiation observation ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →} is a whole-animal behavioural readout, not a defined receptor mechanism, and no binding, enzyme or channel target has been characterised for the isolate. The insect-TRPA1 mechanism that explains catnip’s repellency belongs to nepetalactone, not to this acid ^{4Reference 4Melo N et al. · 2021The irritant receptor TRPA1 mediates the mosquito repellent effect of catnipView study →}.

Pharmacokinetics

There are no absorption, distribution, metabolism, half-life or excretion data for nepetalic acid in humans or animals. As a small, relatively polar monoterpenoid acid that interconverts with its lactone ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}, its ADME has simply not been studied — a gap that matters, since without it the single high-dose mouse behavioural finding ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →} cannot be related to any realistic human exposure.

Clinical Trials

None. No human trial has studied isolated nepetalic acid for any indication. The human data sometimes attached to “catnip” belong to whole-plant or different-species work, not to this molecule ^{5Reference 5Sharma A et al. · 2021The genus Nepeta: traditional uses, phytochemicals and pharmacological propertiesView study →}.

Completed	Planned	Terminated	Preclinical
—(none, isolate)	—	—	One 1978 mouse behavioural study ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →}

Last checked: July 2026.

Prevalence in Nature

Nepetalic acid is essentially a catnip-genus compound. It occurs in the volatile oil of catnip (Nepeta cataria) as a co-marker of the dominant iridoid nepetalactone, and in related catmints (Nepeta spp.). In the foundational 1941 analysis of catnip oil it made up roughly a third of the oil (with nepetalactone ~40–50% and a smaller neutral fraction) ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}, though the proportion — like the nepetalactone content — varies with chemotype, cultivar and provenance. Its absolute concentration in the dried herb (as % dry weight) is not well documented; the figures that exist are proportions of the essential oil, not of the plant material people brew as tea.

Major Natural Sources

Source (Botanical)	Part	Notes
Catnip (Nepeta cataria)	Aerial parts / volatile oil	Principal source; ~33% of the oil in the classic 1941 fractionation, co-occurring with nepetalactone ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}
Catmints (Nepeta spp.)	Aerial parts / volatile oil	Reported across the genus as a nepetalactone co-marker; content varies by species and chemotype

Discovery & Synthesis

Nepetalic acid was first isolated and named in 1941 by S. M. McElvain, R. D. Bright and P. R. Johnson at the University of Wisconsin, in the opening paper of their series on the constituents of catnip volatile oil — the same landmark work that first characterised nepetalactone ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}. Their fractionation separated the oil into nepetalactone (~40–50%), nepetalic acid (~33%) and a neutral fraction (~14%), and established the lactone ↔ acid relationship: nepetalic acid is the ring-opened acid form obtained on hydrolysis of the lactone, and the pair were among the first fully characterised methylcyclopentane (iridoid) monoterpenoids ^{1Reference 1McElvain SM et al. · 1941The constituents of the volatile oil of catnipView study →}.

There is no established commercial production of nepetalic acid as an isolate — it is not a traded therapeutic. In practice it is obtained by extraction/fractionation of catnip oil or generated from nepetalactone by hydrolysis, and it serves mainly as a chemistry and quality-control marker and a synthetic intermediate in iridoid chemistry rather than as a manufactured product. A first total synthesis of the isolated acid is not clearly documented in the sources reviewed here.

Patents: not yet researched.

Toxicity & Safety

Nepetalic acid carries a low flag, consistent with catnip’s long record of safe culinary and medicinal use and the low apparent toxicity of catnip oil in animal studies. The caveat is that this is a low-data low, not a well-characterised one: there is no dedicated isolate toxicology package (no genotoxicity, carcinogenicity, repeat-dose or reproductive-toxicity dataset) for nepetalic acid specifically.

Safety at a Glance

Low / no toxicity

Occurs in a low-toxicity herb. Catnip has a long history of safe use, and its oil shows low acute toxicity in animals; nepetalic acid is one of its normal iridoid constituents.
Do not read catnip’s bioactivity onto this molecule. The cat-attractant and insect-repellent effects are nepetalactone’s; nepetalic acid’s only isolate datapoint is an old, contradicted animal sedative finding ^{2,3Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →Reference 3Massoco CO et al. · 1995AnimalBehavioral effects of acute and long-term administration of catnip (Nepeta cataria) in miceView study →}.
Isolate safety is essentially unstudied. No genotoxicity, organ-toxicity or reproductive-toxicity data exist for the pure compound; absence of findings is not evidence of safety.
Pregnancy/lactation decisions belong to the herb. Catnip the herb is traditionally cautioned as an emmenagogue; that caution attaches to catnip use, not to this molecule-level page.

Dosage

There is no established human dose for nepetalic acid — it is a chemistry/marker compound, not a used therapeutic, and has no clinical use to dose for. The only quantitative figure in the literature is the 62.5 mg/kg dose given to mice in the 1978 barbiturate-sleeping-time study ^{2Reference 2Harney JW et al. · 1978Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta catariaView study →}; that is an experimental animal dose behind a single, contradicted finding, not a human recommendation. Real-world human exposure is incidental — as a minor iridoid constituent of catnip preparations, chiefly the essential oil.

References

McElvain SM, Bright RD, Johnson PR (1941). The constituents of the volatile oil of catnip. I. Nepetalic acid, nepetalactone and related compounds. Journal of the American Chemical Society, 63(6):1558–1563. https://doi.org/10.1021/ja01851a019
Harney JW, Barofsky IM, Leary JD (1978). Behavioral and toxicological studies of cyclopentanoid monoterpenes from Nepeta cataria. Lloydia, 41(4):367–374. https://pubmed.ncbi.nlm.nih.gov/672466/
Massoco CO, Silva MR, Gorniak SL, Spinosa MS, Bernardi MM (1995). Behavioral effects of acute and long-term administration of catnip (Nepeta cataria) in mice. Veterinary and Human Toxicology, 37(6):530–533. https://pubmed.ncbi.nlm.nih.gov/8588288/
Melo N, Capek M, Arenas OM, et al. (2021). The irritant receptor TRPA1 mediates the mosquito repellent effect of catnip. Current Biology, 31(9):1988–1994. https://pubmed.ncbi.nlm.nih.gov/33667373/
Sharma A, Cooper R, Bhardwaj G, Cannoo DS (2021). The genus Nepeta: traditional uses, phytochemicals and pharmacological properties. Journal of Ethnopharmacology, 268:113679. https://pubmed.ncbi.nlm.nih.gov/33307050/