Rose Essential Oil

Rose oil is the portion of the Rose (the plant family Rosa) that possess aromatic properties^[1] and is used for cosmetic fragrances. Several species are used including Rosa centifolia and Rosa gallica, with the species known as Rosa damascena (Damask Rose) being traditionally preferred.^[1] Rose oil, particularly that of the highly prized Damask Rose, has over 90 different volatiles in the aroma.^[2]

There appears to be medicinal usage of Rose in Ayurveda as astringent, tonic, mild laxative, and antibacterial agent and in the treatment of sore throat, enlarged tonsils, cardiac problems, eye disease and gall stones; some usage extending to analgesic and antispasmodic effects.^[1]

Essential Rose Oil from Rosa damascena tends to contain:

• Rose oxide,^[3] a fragrance attributed to rose (also oddly found to contribute to the flavor of Lychee^[4]) and is an oxidative product of Citronellol^[5]
• Citronellol (15.9–35.3%^[1]) and Citronellyl Acetate^[3]
• Geraniol (16.46%^[6] or the range of 8.3–30.2%^[1]) and Geraniol acetate (3.18%)^[7]
• Nerol (8.65%^[6] or the range of 4.0–9.6%^[1])
• Phenylethyl alcohol (4.84%)^[6] and Phenylethylamine (1.12%)^[7]
• Eugenol (1.10%)^[6] and Eugenol Methyl ester (1.5-2.04%)^[7][8]
• Heneicosane (2.6-7.9%)^[1]
• Nonadecane (4.5–16.0%),^[1] Nonadecen-9 (2.18-3.1%),^[8] and Heptadecane (1.25-2.8%)^[8]
• 2-Undecanone^[3]
• Tricosane,^[3] Eicosane (0.62%),^[7] and Pentacosane^[3]
• Germacrane-D (0.39%)^[7]
• β-Caryophyllene^[3]
• Z,Z-Farnesol^[3] at 0.56%^[7]
• Linalool (0.7–2.8%)^[1]
• Terpinen-4-ol (0.39%)^[7]
• α-Pinene (0.81%) and β-Pinene (0.21%)^[7]
• cis-Citral (0.9%) and trans-Citral (1.2%)^[8]

Mostly Rose Oxide and the structurally related Citronellol molecule, with high amounts of both Geraniol and Nerol as well as Nonadecane. Surprisingly, the essential oil contains Phenylethylamine (PEA)

Rose water (not the essential oil, but the water fragment) appears to mostly consist of Phenylethyl alcohol (66.2–79.0%).^[1]

The essential oil confers anti-oxidant properties in vitro, although to a lesser degree than parsely oil in this study.^[9]

The petals of rose also tend to contain common flavonoids including Quercetin, Kaempferol, and Myricetin with the polyphenolic gallic acid;^[10] glycosides of the former two flavonoids.^[11]

Rose essential oil (0.005-0.02% of medium) in HEK293 cells which express the TRPV1 receptor noted that rose oil was able to active this channel with an EC₅₀ of approximately 0.001% due to citronellol (EC₅₀ of 43µM); relative to capsaicin as reference molecule, rose was 45+/-0.3% as effective.^[12] It was the second most effective oil tested in this assay (out of 31 essential oils), second only to tolu balsam but exceeding other common oils such as patchouli or lavender.^[12]

Appears to active TRPV1, albeit not overly potently

Rose essential oil is capable of penetrating the skin when applied as a topical oil, as evidence by relaxing effects of the oil applied topically in persons wearing breathing masks (to omit any odor).^[13]

The retention time of rose oil aromatics on skin cells appears to be a few hours,^[14] and most bioactives appear to be absorbed via skin diffusion with phenylpropanoid compounds (Rose oxide and Citronellol) being the best absorbed relatively and monoterpene hydrocarbons (Nonadecane and other -ane compounds) being poorest, with monoterpene alcohols (Geraniol and Nerol) being intermediate.^[15]

Rose oil, if used on the skin in the form of a cream or massage oil, is capable of also penetrating the skin (in addition to the aroma having bioactivity)

Rose oil has been found to activate TRPV1 channels at an in vitro concentration of 0.005% and 0.02%, which may be related to the components of Citronellol (45+/-4.9% as potent as the active control of capsaicin at the same concentration) and Geraniol (39+/-4.1%).^[12] Geraniol has been noted previously to activate TRPV1.^[16]

The main two bioactives may activate TRPV1

Rose oil bioactives (Citronellol and Geraniol) also appear to interact with PPAR receptors, with 0.01% Rose Oil in medium causing a 2.9-fold induction of PPARα and 2.0-fold induction of PPARγ.^[17] Citronellol caused concentration-dependent increases of PPARα activity (100-400µM causing 2.1-3.1-fold induction) while Geraniol was not significantly effective, both were similarly effective in inducing PPARγ (1.7-1.8-fold at 400µM).^[17] Another study replicated Geraniol's effects on PPARγ and lack of influence on PPARα.^[18] Nerol was inactive on both proteins.^[17]

There appears to be some influence on PPARγ and PPARα

A study giving oral (1.5mL/kg) and inhaled (0.15mL/kg inhaled for 15 minutes daily) rose oil () for 28 days to rats depressed from chronic mild stress (CMS) noted that the vapor but not oral intake was able to exert anti-depressive effects as assessed by a sucrose preference test.^[7] The increase in lipid peroxidation in the cerebral cortex seen with stress was also reduced with rose aroma, but there was no significant influence of oral intake.^[7]

One rodent study supports to notion of anti-depressive effects of Rose aroma, but not oral intake

One study in 10 healthy adults under EEG measuring Event Related Potentials (ERPs) using a push/wait paradigm (blinding possibly failed, as a descriptive word for rose oil by participants was 'rose') noted that rose failed to significantly influence alpha, beta, nor theta brainwaves while it trended to reduce alpha waves in both posterior quadrants.^[19] Another subset of persons used Incense (mostly composed of Agarwood) noted that this was able to increase alpha2 brainwaves in all quadrants, with more efficacy in the posterior half.^[19]

No significant influence noted on alpha wave patterns

The relaxing effect of Rose Oil (reduced autonomic system activation as assessed by reducing blood pressure and breathing rate) has been confirmed to occur via transdermal absorption in a study using breathing masks to exclude aroma perception.^[13]

The relaxing effects of Rose Oil appear to be absorbed through the skin when applied topically (transdermally)

In rats, inhalation of Rose oil (from Rosa alba) was able to attenuate the increase in corticosterone (to about half that observed in control) from an acute stress test and attenuated the increase in Fos expression in the Paraventricular Nuclei (PVN) of stressed rats; both indicative of stress reducing effects.^[6]

Anxiety reducing effects of Rose oil inhalation (1-5% oil solution applied at 2mL on a cotton swab) noted anxiety reducing effects which were similar at all doses in an elevated maze plus test, with the time spent in open arms being of similar potenct to 1-2mg/kg injections of Diazepam while the number of visits trended to be less potent than Diazepam (although still not significantly different).^[20] These results were replicated later (in gerbils) in an elevated maze plus test as well as a black-white box test where rose oil again was of similar potency to Diazepam; this study also noted that the anxiety reducing effects were preserved with chronic (2 week) inhalation rather than acute (1 day) and that the estrus cycle had no influence on anxiety reducing effects of Rose aroma.^[21] It is thought that the mechanisms are not mediated via the benzodiazepine receptors, as the observed profile of effects differed from Diazepam (Benzodiazepine agonist).^[21]

In rats, the aroma of rose oil appears to both have anti-stress and anti-anxiety properties. The efficacy, relative to the active control of Diazepam (Valium) on anxiety is similar

In humans, an open label study using a nametag with Rose oil scent for the duration of a day in otherwise healthy females during University Exam period (thought to be a model of chronic stress in the real world) noted that the group using Rose oil had significantly less salivary cortisol.^[6] In order to see if a placebo effect was involved, subjects were later blinded to the aroma and given either Rose Oil or placebo (Jasmine) and acutely stressed via a Stroop color-word test; Rose oil inhalation appeared to reduce salivary cortisol more than control or placebo.^[6]

There appears to be some stress reducing properties associated with rose oil aroma in humans

In Geller and Vogel conflict tests in male ICR mice, the oil of Rosa centiflora (injections 20 minutes before testing) at 100-800mg/kg noted that 400-800mg/kg of Rose oil produced significant anti-conflict effects and that this was replicated with the bioactives Citronellol and 2-phenethyl alcohol (both constituents of Rose Oil).^[22]

Possible anti-conflict (anger reducting) effects of Rose oil, but the high doses required via injections may not apply to aromatics nor oral ingestion

In 61 college-aged females with higher than average menstrual pain (6-10 on a VAS rating scale), an abdominal massage with 2 drops of Lavandula officinalis (Lavender) to one drop Clary Sage and one drop Rose (as Rosa centifolia) was compared to placebo aromatherapy (almond oil, same method of appplication and volume of 5cc) and control (no aromatherapy). It was noted that aromatherapy was associated with an average reduction in pain from 7 (0-10 rating scale) down to 5 and then 3 on days 1 and 2, respectively; control failed to reduce pain, and placebo aromatherapy appears to work in some persons to a lesser extent than combination therapy (herb intervention still significantly greater than the placebo group).^[23] The authors noted that although heavier flows appears to be correlated with greater pain,^[24] that there were no significant difference between groups.^[23] A later study was conducted with Rose substitute with Marjoram for similar effects, suggesting that Rose plays a minor role in the analgesic effects observed.

One study using Rose oil in isolation in persons with renal colic given standard therapy (diclofenac) that the addition of aromatherapy with rose (relative to placebo aromatherapy) noted that the inhalation of rose aroma was able to reduce pain (as assessed by VAS) at 10 and 30 minutes of continued inhalation.^[25]

Currently weak evidence to support a pain reducing effect of Rose aroma, with only one study using rose essential oil by itself (but even then, it was in addition to a standard pain killer relative to pain killer in isolation)

Damask Rose has been found to, in a model of Drosophila melanogaster (fruit fly), improve lifespan and reduce mortality following oral ingestion^[26] which has been quantified as an increase in both mean and maximum lifespan (by about 10%) which was associated with no alterations of mitochondrial respiration nor soluble proteins;^[27] as these two mechanisms are noted in caloric restriction^[28][29] it is thought that the influence of Rose is mediated by alternate pathways.^[27]

A downregualtion of the two heat-shock proteins HSP22 and HSP70 were noted in fruit flies given Rose extract, which compromised survival at 37°C by sensitizing the flies to heat. There was no influence on heat-induced upregulation of these two proteins, although there was less expression of them both when at room temperature;^[27] as HSP22 is known to be significantly upregulated in aged mitochondria (60-fold^[30]) and both generally being involved in the aging process,^[31] it is thought these HSPs may underlie effects of Rose.

Oral ingestion of Rose has been noted to increase lifespan in fruit flies

In rats, isolated Citronellol is able to reduce blood pressure in a dose-dependent manner with maximal efficacy at 20mg/kg (injections) resulting in a reduction of 48+/-2% and a reduction of tachycardia by approximately 21+/-1%.^[32]

One human study has noted reductions in blood pressure associated with rose essential oil (aroma was controlled for via breathing mask, topical administration),^[13] this reduction in blood pressure was associated with other relaxaing biomarkers (ex. reduced breathing rate).

Has been noted to reduce blood pressure, possible that it is merely an acute effect rather than a chronic (curative) effect

LPS-induced COX-2 mRNA induction has been noted to be suppressed to 42% in the presence of 0.01% Rose Oil in isolated Bovine Aortic Endothelial Cells (BAEC).^[17] This was thought to be due to Citronellol and Geraniol activating the PPAR proteins, PPARγ (both) and PPARα (Citronellol only).^[17]

(+)-Rose oxide injections (50-100mg/kg, 25mg/kg not reaching significance on any parameter) noted dose-dependent reductions in biomarkers of inflammation in rats exposed to a formalin test (100mg/kg of comparable potency to 10mg/kg Indomethacin), a complete Freund's adjuvant (CFA; 50-100mg/kg being comparable to 2mg/kg Dexamethasone) and carrageenan-induced paw edema (50-100mg/kg being comparable to Dexamethasone) while being noted to reduce circulating IL-1β in mice treated with CFA to a similar level as Dexamethasone; Rose oxide failed to at all influence TNF-α concentrations, and exhibited an myeloperoxidase (MPO) reducing ability at all doses.^[4]

Has shown some anti-inflammatory properties (moderate to high potency) following injections of isolated Rose oxide in rats

In a trial where persons were given rose aroma in a blinded manner, the aroma of Rose as well as the aromas of Lavender or Patchouli all failed to significantly influence immunological markers of neutrophil actions.^[8]

A trend was noted for the above relaxing herbs to reduce Plasminogen activation inhibitor 1 (PAI-1) activity, but this failed to reach statistical significance for the whole group (reached significance for a female subset).^[8] The opposite trend (an increase in PAI-1) was noted for the stimulatory aromas of Grapefruit, Fennel, and Pepper.^[8]

Aside from possible weak influences on PAI-1 in females, there does not appear to be substantial human evidence linking immunity to the aroma of a rose

At least one study has noted that Rose Oil aroma (unblinded) is associated with reduced salivary cortisol during stressful periods, relative to a control not given any aroma.^[6]

At least one study noted reductions in cortisol, associated with an overall reduction in stress

In rats exposed to formaldehyde aroma (10ppm/L for an hour daily for 35 days) noted that, in a group which subsequently inhaled rose aroma (1mL for an hour) noted that Rose was able to preserve 55% of the reduction in testosterone seen in formaldehyde control.^[33] The preservation of testosterone in serum as well as preservation of sperm motility, count, and morphology (near absolute protection) were through to be due to protection from formaldehyde associated with rose aroma.^[33]

In rats, aromatherapy with rose appears to protect testicles from oxidative damage induced by pro-oxidative compounds present in the air

Stress appears to negatively influence skin quality secondary to increasing transepidermal water loss (TEWL), a passage of water from the epidermis (skin) to the outside of the body and is thought to be indicative of damage to skin cells;^[34][35] this term is used mostly in cosmetology, and is noted in research animals subject to chronic stress.^[35][36]

One study measuring the interaction of Rose Oil and stress that noted a reduction in salivary cortisol (thought to be indicative of stress) noted that the group given Rose oil aroma had less TEWL than the stressed control.^[6]

Secondary to a reduction in stress (not inherently unique to Rose Oil), reduced water loss from the skin has been reported and thought to indicate less skin damage

Contact dermatitis has been reported from Rose oil due to the Geraniol content.^[37]