Compound Monograph

Limonene

Terpenoids Monoterpenes Natural (plant-derived)

Limonene (chiefly D-/R-(+)-limonene) is the citrus-peel monoterpene — one of the most abundant terpenes in nature and a high-volume food, fragrance and solvent chemical. Unusually for a plant terpene it has real human data as the isolate — a Phase I cancer trial, a pre-surgical breast-tissue study and small heartburn trials — but it is extensively first-pass-metabolized to perillic acid and other acids, which frames everything downstream.

Sources · 36

Where Does It Come From?

Limonene is a naturally occurring monocyclic monoterpene, found in Buchu, Juniper, Fennel and 33 other sources. It is well tolerated orally (low toxicity).

Principal source Buchu Agathosma betulina Herb monograph → Source Angelica Angelica archangelica Herb monograph → Source Black Pepper Piper nigrum Herb monograph → Source Black Walnut Juglans nigra Herb monograph → Source Cannabis Cannabis sativa Herb monograph → Source Cashew Anacardium occidentale Herb monograph → Source Chaste Tree Vitex agnus-castus Herb monograph → Source Chilca Baccharis latifolia Herb monograph → Source Chinese Skullcap Scutellaria baicalensis Herb monograph → Source Chir Pine Pinus roxburghii Herb monograph → Source Cornflower Centaurea cyanus Herb monograph → Source Epazote Dysphania ambrosioides Herb monograph → Source Eucalyptus Eucalyptus globulus Herb monograph → Source Fennel Foeniculum vulgare Herb monograph → Source Fish Mint Houttuynia cordata Herb monograph → Source German Chamomile Matricaria chamomilla Herb monograph → Source Hyssop Hyssopus officinalis Herb monograph → Source Juniper Juniperus communis Herb monograph → Source Korean Pine Pinus koraiensis Herb monograph → Photo coming soon Source Korean Red Pine Pinus densiflora Herb monograph → Source Lemongrass Cymbopogon citratus Herb monograph → Photo coming soon Source Maritime Pine Pinus pinaster Herb monograph → Source Masson Pine Pinus massoniana Herb monograph → Source Mexican Tarragon Tagetes lucida Herb monograph → Source Monterey Pine Pinus radiata Herb monograph → Source Mugo Pine Pinus mugo Herb monograph → Source Muira Puama Ptychopetalum olacoides Herb monograph → Source Peppermint Mentha × piperita Herb monograph → Source Pine Pinus sylvestris Herb monograph → Source Spearmint Mentha spicata Herb monograph → Source Tarragon Artemisia dracunculus Herb monograph → Source Yarrow Achillea millefolium Herb monograph →
Also found in
Caraway Monograph coming soon
Celery seed Monograph coming soon
Citrus peel Monograph coming soon
Dill Monograph coming soon

Concentration

Content by Source

Reported concentrations across the plants that contain limonene — the bar marks the typical level, the line shows the reported range.

Typical level Reported range % of oil
Sweet orange (Citrus sinensis) peel oil 90–96 [17]
Buchu (Agathosma betulina) leaf oil 12–17 [19]
Juniper (Juniperus communis) berry oil 1–14 [20]
Peppermint (Mentha × piperita) leaf oil 1–5 [22]
Lemongrass (Cymbopogon citratus) leaf oil 1–3 [21]

Literature figures for varying plant parts and preparations. Read them as a comparative guide, not exact assays.

Limonene at a Glance

Limonene — chiefly the D-/R-(+)- enantiomer — is the citrus-peel monoterpene, one of the most abundant terpenes in nature and a high-volume industrial chemical used as a food flavouring, a fragrance and a solvent.

It is one of the few plant terpenes with human data on the isolate, including a Phase I cancer trial, which places it alongside 1,8-cineole as an exception in a class usually studied only as essential oils.

Its other studied uses are gastro-oesophageal reflux — where the mechanism is unusual and physical rather than pharmacological — and anxiolytic effects through inhalation.

What It's Used For

Limonene is a monocyclic monoterpene — the molecule that gives citrus peel its scent, and one of the most abundant terpenes in nature. It exists as two mirror-image forms: D-limonene (R-(+)-limonene), the orange-scented enantiomer that dominates citrus peel oil and carries essentially all the human data, and L-limonene (S-(−)-limonene), the more turpentine/pine-scented form found in caraway and dill; unless stated otherwise, “limonene” below means the D-form. It turns up across this database as a minor-to-moderate component of volatile oils — buchu, juniper, fennel, peppermint, lemongrass and many others — and is a relative of the other volatile monoterpenes α-pinene, β-pinene and myrcene. Two things frame its evidence. First, limonene is unusual among plant terpenes in having genuine human data on the isolated molecule — a Phase I oncology trial, a pre-surgical breast-tissue study and small heartburn trials — rather than only whole-oil or rodent work. Second, and load-bearing: limonene is well absorbed but almost entirely first-pass-metabolized, appearing in blood mostly as the acids perillic acid and dihydroperillic acid plus limonene-1,2-diol, so much of its systemic pharmacology is really the pharmacology of those metabolites 1,5,6Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →Reference 5Poon GK et al. · 1996Clinical trialIdentification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry — human PKView study →Reference 6Schmidt L · 2017R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK studyView study →.

Best human-tested signal — chemoprevention/anticancer:isolated D-limonene reached its metabolites at bioactive plasma levels in a Phase I trial (one durable breast-cancer partial response) 1Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →, concentrated in breast tissue and lowered tumor cyclin D1 in a pre-surgical study 2Reference 2Miller JA et al. · 2013Clinical trialHuman breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical studyView study → — promising but early, with no efficacy RCT.
Small human data — GERD/heartburn:low-quality trials (patent-derived, tiny) report symptom relief from intermittent 1 g D-limonene capsules; widely cited but not confirmed by any robust study 7Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →.
Preclinical, mechanistically coherent:inhaled/oral limonene is anxiolytic and antidepressant-like in rodents (adenosine A2A → dopamine/GABA; monoamine/HPA-axis effects) 8,9Reference 8Song Y et al. · 2021AnimalLimonene has anti-anxiety activity via adenosine A2A receptor-mediated regulation of dopaminergic and GABAergic neuronal function in the striatum — mouse in vivoView study →Reference 9Zhang LL et al. · 2019AnimalAntidepressant-like effect of Citrus sinensis (L.) Osbeck essential oil and its main component limonene on mice — mouse in vivoView study →, and improves lipids and glucose in diet-induced-obese rodents 10,11Reference 10Jing L et al. · 2013AnimalPreventive and ameliorating effects of citrus D-limonene on dyslipidemia and hyperglycemia in mice with high-fat diet-induced obesity — mouse in vivoView study →Reference 11Santiago JV et al. · 2012AnimalDietary d-limonene alleviates insulin resistance and oxidative stress-induced liver injury in high-fat diet and L-NAME-treated rats — rat in vivoView study →.
The caveat:extensive first-pass metabolism to perillic acid and diols means “limonene” exposure in the body is largely its metabolites; most non-cancer findings are animal, and a citrus-oil result is not a limonene result 5,6Reference 5Poon GK et al. · 1996Clinical trialIdentification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry — human PKView study →Reference 6Schmidt L · 2017R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK studyView study →.
Evidence by IndicationStrength of support · Beta

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-plant match and bioavailability. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric. Each application links down to its write-up.

Mechanisms

Target / pathwayEffectRelevant to
Cyclin D1 / cell-cycle (via perillyl-type metabolites)↓ proliferation; isoprenylation/Ras interference in models
Cancer chemoprevention
Adenosine A2A → dopamine/GABA (striatum)Anxiolytic; antagonist-reversible
Anxiolytic / mood
Monoamines, HPA axis, hippocampal BDNFRestores 5-HT/NA/DA; dampens stress response
Mood / antidepressant-like
PPARα ↑ / LXRβ ↓↓ hepatic lipogenesis, improved lipids & glucose
Metabolic
NF-κB / iNOS-NO (IL-1β-stimulated chondrocytes)↓ inflammatory & catabolic mediators
Anti-inflammatory
Radical scavenging (antioxidant)↓ lipid peroxidation, ↑ antioxidant defenses
Antioxidantgastroprotection

Pharmacokinetics

Limonene’s defining pharmacological fact is not poor absorption but extensive first-pass metabolism. It is lipophilic and well absorbed orally, but it is rapidly oxidized by cytochrome P450 — chiefly CYP2C9 and CYP2C19 (with CYP2C8/2C18/3A4 contributing) — via 6- and 7-hydroxylation to trans-carveol and perillyl alcohol, which are further oxidized to the circulating acids perillic acid and dihydroperillic acid, plus limonene-1,2-diol, uroterpenol and limonene-8,9-diol 4,6,7Reference 4Miyazawa M et al. · 2002In vitroMetabolism of (+)- and (−)-limonenes to respective carveols and perillyl alcohols by CYP2C9 and CYP2C19 in human liver microsomes — in vitro humanView study →Reference 6Schmidt L · 2017R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK studyView study →Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →. In the Phase I trial, parent D-limonene peaked around 10–20 µM while perillic acid reached much higher plasma levels (~20–71 µM), i.e. the metabolites dominate systemic exposure 1,5Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →Reference 5Poon GK et al. · 1996Clinical trialIdentification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry — human PKView study →. In controlled human oral dosing, blood metabolites peak at ~1–2 h and clear with half-lives of roughly 0.7–2.5 h (limonene-1,2-diol slowest), and parent limonene is largely undetectable in blood by 5 h — the signature of rapid, near-complete first-pass conversion 6Reference 6Schmidt L · 2017R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK studyView study →. The practical upshot: dosing limonene is effectively dosing perillic acid and the diols, so mechanistic work on “limonene” should be read against which species actually circulates.

Clinical trials

Limonene has real but sparse human trial activity, almost all in oncology chemoprevention — a Phase I dose-finding/PK study 1Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study → and a pre-surgical breast-tissue biomarker study 2,3Reference 2Miller JA et al. · 2013Clinical trialHuman breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical studyView study →Reference 3Miller JA et al. · 2015Plasma metabolomic profiles of breast cancer patients after short-term limonene intervention — human intervention studyView study → — plus small, low-quality heartburn trials 7Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →; there are no large efficacy RCTs for any indication, and the anxiolytic and metabolic data are entirely preclinical.

CompletedPlannedTerminatedPreclinical
Phase I + pre-surgical biomarker (oncology); small GERDFew—Extensive

Last checked: July 2026.

Isolate vs. Plant Studies

Limonene sits at an unusually favorable point on the isolate-vs-plant spectrum for a volatile terpene: its human data genuinely use the purified molecule. The Phase I oncology trial dosed pharmaceutical-grade D-limonene 1Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →, the breast study gave 2 g/day of limonene as the isolate 2Reference 2Miller JA et al. · 2013Clinical trialHuman breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical studyView study →, and the heartburn trials used purified D-limonene capsules 7Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study → — none are whole-oil stand-ins. That said, most of the non-cancer mechanistic literature is mixed: the mood work runs both ways (isolated limonene in the A2A study 8Reference 8Song Y et al. · 2021AnimalLimonene has anti-anxiety activity via adenosine A2A receptor-mediated regulation of dopaminergic and GABAergic neuronal function in the striatum — mouse in vivoView study →; whole sweet-orange oil plus its limonene component in the depression model 9Reference 9Zhang LL et al. · 2019AnimalAntidepressant-like effect of Citrus sinensis (L.) Osbeck essential oil and its main component limonene on mice — mouse in vivoView study →), and much of the antimicrobial/antioxidant reputation rests on citrus and herb essential oils where limonene is only the major component, not the sole actor. On the source-herb pages here, limonene is almost always one terpene within a whole volatile oil (buchu, juniper, fennel, peppermint), so those findings describe the oils, not the molecule. Read the oncology and heartburn trials as evidence for limonene itself, and the aromatherapy/essential-oil literature as evidence for the oils.

Prevalence in Nature

Limonene is one of the most widely distributed monoterpenes in the plant kingdom, but its marquee reservoir is citrus peel: the cold-pressed peel oil of sweet orange (Citrus sinensis) is roughly 90–95% D-limonene, and it dominates the peel oils of lemon, lime, grapefruit and mandarin too 17,18Reference 17Vieira AJ et al. · 2018ReviewLimonene: aroma of innovation in health and disease — reviewView study →Reference 18Anandakumar P et al. · 2021ReviewD-limonene: a multifunctional compound with potent therapeutic effects — reviewView study →. Beyond the Rutaceae, it is a major constituent of caraway and dill seed oil (largely as the (S)-(−) enantiomer, alongside carvone), celery seed, conifer needle and resin oils (Pinaceae, Cupressaceae — e.g. juniper berry oil, pine), and a minor-to-moderate terpene across Lamiaceae (peppermint), Apiaceae (fennel, angelica), Poaceae (lemongrass) and Cannabaceae (cannabis) volatile oils. The enantiomer split is characteristic: citrus and conifers make chiefly R-(+)-limonene (orange scent), while caraway, dill and spearmint biosynthesis runs through (S)-(−)-limonene 17Reference 17Vieira AJ et al. · 2018ReviewLimonene: aroma of innovation in health and disease — reviewView study →.

Biosynthetically it is a textbook monoterpene, built in the plastid via the MEP pathway: the C10 precursor geranyl diphosphate is cyclized in a single committed step by a limonene synthase (a monoterpene cyclase — (R)-limonene synthase in citrus, (S)-limonene synthase in caraway/mint), making limonene the branch-point scaffold from which carvone, perillyl and carveol derivatives are elaborated 17Reference 17Vieira AJ et al. · 2018ReviewLimonene: aroma of innovation in health and disease — reviewView study →. It is essentially a plant product; there is no established animal biosynthetic source, though it is ubiquitous enough in diet and environment to appear as a trace body metabolite.

Discovery & Synthesis

Limonene has been known as the principal terpene of citrus peel since the 19th century, when terpene chemistry was first systematized (the work associated with Otto Wallach, Nobel laureate 1910); its name derives from the French limon / lemon, and the optically inactive racemate was long known by the separate name “dipentene.” The two enantiomers were later resolved and their opposite scents — R-(+) “orange,” S-(−) “turpentine/lemon-herb” — became a classic teaching example of chirality and olfaction. No single first-total-synthesis is a landmark for limonene, because it has never needed to be synthesized commercially: it is produced in enormous industrial volume as a by-product of citrus-juice processing, recovered by cold-pressing or steam-distilling the spent peel, and sold both as food-grade D-limonene (flavor/fragrance) and as a “green” degreasing solvent replacing petroleum distillates. Global output runs to tens of thousands of tonnes a year, making limonene one of the highest-tonnage natural terpenes in commerce 17,18Reference 17Vieira AJ et al. · 2018ReviewLimonene: aroma of innovation in health and disease — reviewView study →Reference 18Anandakumar P et al. · 2021ReviewD-limonene: a multifunctional compound with potent therapeutic effects — reviewView study →.

Patents: not yet researched (future patent-loop pass).

Toxicity & Safety

Limonene carries a low toxicity flag. D-limonene is listed as Generally Recognized As Safe (GRAS) as a flavoring, is consumed routinely in citrus-containing foods, and was well tolerated in humans across single and repeated dosing up to a year — including the grams-per-day Phase I oncology doses, where toxicity was limited to gastrointestinal upset at the very top of the range 1,7Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →. The one historically alarming finding needs stating honestly and in proportion: high oral doses of D-limonene cause kidney tumors in male rats, but this is a male-rat-specific mechanism with no human counterpart. It works through α2u-globulin nephropathy — D-limonene’s metabolite binds α2u-globulin, a protein synthesized only by adult male rats, causing protein accumulation, tubular injury and, eventually, tumors 13,14Reference 13Lehman-McKeeman LD et al. · 1989Animald-Limonene-induced male rat-specific nephrotoxicity: evaluation of the association between d-limonene and α2u-globulin — rat mechanism studyView study →Reference 14Dietrich DR · 1991AnimalThe presence of α2u-globulin is necessary for d-limonene promotion of male rat kidney tumors — rat mechanism studyView study →. Humans (and female rats, and mice) do not make a protein that behaves this way, so IARC and the US EPA judged these tumors not predictive of human risk, and the D-limonene safety literature explicitly concludes it poses no mutagenic, carcinogenic or nephrotoxic hazard to people 7,15Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →Reference 15Flamm WG · 1991AnimalThe human relevance of the renal tumor-inducing potential of d-limonene in male rats: implications for risk assessment — risk-assessment reviewView study →. This is a different situation from the sibling terpene myrcene, whose NTP carcinogenicity signal spans two species and both a kidney and a liver mechanism — limonene has no such multi-species signal.

The genuine day-to-day caution is skin sensitization from oxidized limonene. Fresh limonene is at most a very weak contact allergen, but on exposure to air and light it autoxidizes to hydroperoxides and other oxygenated products that are potent contact allergens — oxidized D-limonene is a common cause of positive patch tests among dermatitis patients — so limonene-rich oils should be stored cool and dark, kept sealed, and diluted for topical use 16Reference 16Karlberg AT · 1997Contact allergy to oxidized d-limonene among dermatitis patients — clinical patch-test studyView study →. For drug interactions, the mechanistic flag is metabolic: limonene is oxidized by CYP2C9 and CYP2C19 4Reference 4Miyazawa M et al. · 2002In vitroMetabolism of (+)- and (−)-limonenes to respective carveols and perillyl alcohols by CYP2C9 and CYP2C19 in human liver microsomes — in vitro humanView study →, and at the high doses used in cancer studies limonene/perillyl compounds can perturb CYP-mediated metabolism, so an interaction with narrow-margin CYP2C substrates is theoretically plausible — but no clinically documented human interaction dataset exists for dietary or supplemental intake. Formal human interaction data, and pregnancy/lactation exposure data for the isolated molecule, are limited; the low-risk read applies to culinary and studied supplemental levels, not to bulk or undiluted essential-oil use.

Dosage

There is no established human supplement dose for limonene, and nothing here is a recommendation. The research doses vary enormously by purpose. Chemoprevention/oncology studies used grams per day: the Phase I trial escalated to a maximum tolerated 8 g/m²/day (with activity seen at those high doses) 1Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →, while the pre-surgical breast study used a much more modest 2 g/day for 2–6 weeks 2Reference 2Miller JA et al. · 2013Clinical trialHuman breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical studyView study →. The heartburn trials used roughly 1,000 mg every other day for about 20 days 7Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →. The rodent metabolic and behavioral work used doses (mg/kg) that don’t translate directly to people 10,11Reference 10Jing L et al. · 2013AnimalPreventive and ameliorating effects of citrus D-limonene on dyslipidemia and hyperglycemia in mice with high-fat diet-induced obesity — mouse in vivoView study →Reference 11Santiago JV et al. · 2012AnimalDietary d-limonene alleviates insulin resistance and oxidative stress-induced liver injury in high-fat diet and L-NAME-treated rats — rat in vivoView study →.

ApplicationFormDose (studied)Source
Advanced cancer (Phase I)Oral D-limoneneup to 8 g/m²/day (MTD)1Reference 1Vigushin DM et al. · 1998Clinical trialPhase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trialView study →
Breast (pre-surgical biomarker)Oral limonene2 g/day, 2–6 weeks2Reference 2Miller JA et al. · 2013Clinical trialHuman breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical studyView study →
Heartburn / GERDD-limonene capsule~1,000 mg every other day7Reference 7Sun J · 2007ReviewD-Limonene: safety and clinical applications — reviewView study →

Because limonene is extensively converted to perillic acid and diols on absorption, the circulating exposure is largely its metabolites rather than limonene itself 5,6Reference 5Poon GK et al. · 1996Clinical trialIdentification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry — human PKView study →Reference 6Schmidt L · 2017R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK studyView study →. These are doses studied in research and are not a personal recommendation.

References

  1. Vigushin DM, Poon GK, Boddy A, English J, Halbert GW, Pagonis C, et al. (1998). Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer — Phase I clinical trial. Cancer Chemotherapy and Pharmacology, 42(2), 111–117. https://pubmed.ncbi.nlm.nih.gov/9654110/
  2. Miller JA, Lang JE, Ley M, Nagle R, Hsu CH, Thompson PA, et al. (2013). Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer — pre-surgical clinical study. Cancer Prevention Research, 6(6), 577–584. https://pubmed.ncbi.nlm.nih.gov/23554130/
  3. Miller JA, Pappan K, Thompson PA, Want EJ, Siskos AP, Keun HC, et al. (2015). Plasma metabolomic profiles of breast cancer patients after short-term limonene intervention — human intervention study. Cancer Prevention Research, 8(1), 86–93. https://pubmed.ncbi.nlm.nih.gov/25388013/
  4. Miyazawa M, Shindo M, Shimada T. (2002). Metabolism of (+)- and (−)-limonenes to respective carveols and perillyl alcohols by CYP2C9 and CYP2C19 in human liver microsomes — in vitro human. Drug Metabolism and Disposition, 30(5), 602–607. https://pubmed.ncbi.nlm.nih.gov/11950794/
  5. Poon GK, Vigushin D, Griggs LJ, Rowlands MG, Coombes RC, Jarman M. (1996). Identification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry — human PK. Drug Metabolism and Disposition, 24(5), 565–571. https://pubmed.ncbi.nlm.nih.gov/8723738/
  6. Schmidt L, Göen T. (2017). R-Limonene metabolism in humans and metabolite kinetics after oral administration — human PK study. Archives of Toxicology, 91(3), 1175–1185. https://pubmed.ncbi.nlm.nih.gov/27325307/
  7. Sun J. (2007). D-Limonene: safety and clinical applications — review. Alternative Medicine Review, 12(3), 259–264. https://pubmed.ncbi.nlm.nih.gov/18072821/
  8. Song Y, Seo S, Lamichhane S, Seo J, Hong JT, Cha HJ, Yun J. (2021). Limonene has anti-anxiety activity via adenosine A2A receptor-mediated regulation of dopaminergic and GABAergic neuronal function in the striatum — mouse in vivo. Phytomedicine, 83, 153474. https://pubmed.ncbi.nlm.nih.gov/33548867/
  9. Zhang LL, Yang ZY, Fan G, Ren JN, Yin KJ, Pan SY. (2019). Antidepressant-like effect of Citrus sinensis (L.) Osbeck essential oil and its main component limonene on mice — mouse in vivo. Journal of Agricultural and Food Chemistry, 67(50), 13817–13828. https://pubmed.ncbi.nlm.nih.gov/30905156/
  10. Jing L, Zhang Y, Fan S, Gu M, Guan Y, Lu X, et al. (2013). Preventive and ameliorating effects of citrus D-limonene on dyslipidemia and hyperglycemia in mice with high-fat diet-induced obesity — mouse in vivo. European Journal of Pharmacology, 715(1–3), 46–55. https://pubmed.ncbi.nlm.nih.gov/23838456/
  11. Santiago JV, Jayachitra J, Shenbagam M, Nalini N. (2012). Dietary d-limonene alleviates insulin resistance and oxidative stress-induced liver injury in high-fat diet and L-NAME-treated rats — rat in vivo. European Journal of Nutrition, 51(1), 57–68. https://pubmed.ncbi.nlm.nih.gov/21445622/
  12. Rufino AT, Ribeiro M, Sousa C, Judas F, Salgueiro L, Cavaleiro C, Mendes AF. (2015). Evaluation of the anti-inflammatory, anti-catabolic and pro-anabolic effects of E-caryophyllene, myrcene and limonene in a cell model of osteoarthritis — in vitro (human chondrocytes). European Journal of Pharmacology, 750, 141–150. https://pubmed.ncbi.nlm.nih.gov/25622554/
  13. Lehman-McKeeman LD, Rodriguez PA, Takigiku R, Caudill D, Fey ML. (1989). d-Limonene-induced male rat-specific nephrotoxicity: evaluation of the association between d-limonene and α2u-globulin — rat mechanism study. Toxicology and Applied Pharmacology, 99(2), 250–259. https://pubmed.ncbi.nlm.nih.gov/2472019/
  14. Dietrich DR, Swenberg JA (1991). The presence of α2u-globulin is necessary for d-limonene promotion of male rat kidney tumors — rat mechanism study. Cancer Research, 51(19), 5182–5185. https://pubmed.ncbi.nlm.nih.gov/1711412/
  15. Flamm WG, Lehman-McKeeman LD. (1991). The human relevance of the renal tumor-inducing potential of d-limonene in male rats: implications for risk assessment — risk-assessment review. Regulatory Toxicology and Pharmacology, 13(1), 70–86. https://pubmed.ncbi.nlm.nih.gov/2024047/
  16. Karlberg AT, Dooms-Goossens A. (1997). Contact allergy to oxidized d-limonene among dermatitis patients — clinical patch-test study. Contact Dermatitis, 36(4), 201–206. https://pubmed.ncbi.nlm.nih.gov/9165203/
  17. Vieira AJ, Beserra FP, Souza MC, Totti BM, Rozza AL. (2018). Limonene: aroma of innovation in health and disease — review. Chemico-Biological Interactions, 283, 97–106. https://pubmed.ncbi.nlm.nih.gov/29427589/
  18. Anandakumar P, Kamaraj S, Vanitha MK. (2021). D-limonene: a multifunctional compound with potent therapeutic effects — review. Journal of Food Biochemistry, 45(1), e13566. https://pubmed.ncbi.nlm.nih.gov/33289132/
  19. Moolla A, Viljoen AM. (2008). ‘Buchu’ — Agathosma betulina and Agathosma crenulata (Rutaceae): a review — botanical/phytochemical review (limonene ~12–17% of oil). Journal of Ethnopharmacology, 119(3), 413–419. https://pubmed.ncbi.nlm.nih.gov/18725278/
  20. Höferl M, Stoilova I, Schmidt E, Wanner J, Jirovetz L, Trifonova D, et al. (2014). Chemical composition and antioxidant properties of juniper berry (Juniperus communis L.) essential oil — composition study (limonene ~1–14% of oil). Antioxidants, 3(1), 81–98. https://pubmed.ncbi.nlm.nih.gov/26784665/
  21. Ekpenyong CE, Akpan E, Nyoh A. (2015). Ethnopharmacology, phytochemistry, and biological activities of Cymbopogon citratus (DC.) Stapf extracts — review (limonene ~2% of leaf oil). Chinese Journal of Natural Medicines, 13(5), 321–337. https://pubmed.ncbi.nlm.nih.gov/25986281/
  22. Saharkhiz MJ, Motamedi M, Zomorodian K, Pakshir K, Miri R, Hemyari K. (2012). Chemical composition, antifungal and antibiofilm activities of the essential oil of Mentha piperita L. — composition/activity study (limonene ~1–5% of oil). ISRN Pharmaceutics, 2012, 718645. https://pubmed.ncbi.nlm.nih.gov/23304561/