Limonene is one of the most widely consumed plant terpenes. It is abundant in fruits such as oranges, lemons, and grapes. Cannabis lovers who prefer strains with a citrus aroma are fans of limonene-dominant strains.
Its effects are energizing and mood-uplifting—perfect for dealing with tedious daily tasks. Some of its medical benefits include, but are not limited to, anti-depression, anti-anxiety, anti-cancer, and acid reflux alleviation.
The chemical structure of limonene contains a chiral carbon, which makes it slightly unstable and thus it could exist in different forms as an isomer. Optical activities on the compound will make it exist in two different structures, which are mirror images of each other. Hence, enantiomers. Of the two forms ― L-Limonene and D-Limonene ― the latter is the most abundant and well researched. There is a need for more research studies considering the effect of the L-Limonene.
The D-Limonene is abundant in citrus fruits while the L-Limonene can be found in pines.
Although limonene is listed safe for use as a flavor by the FDA, it is important to be conscious of the dose ingested as there are some side effects associated with it so far. However, these side effects are nonlethargic.
Strains rich in limonene include Super Lemon Haze and OG Kush, among others.
Introduction
Limonene is the most abundant terpene (after myrcene) among the major terpenes identified so far in the cannabis plant. It is produced in the trichomes, specifically in the resin gland.
Limonene exhibits modifying actions in relation to other phytocannabinoid compounds (like THC and CBD) just like other major terpenes. But in addition, it also offers some notable health beneficial effects that are peculiar to it.
Flavors and Aroma
Almost everyone has ingested limonene in some form, including non-cannabis users. Limonene flavors and aromas are presented as pleasant, sweet, and fresh with a strong citrus scent.
Strains high in limonene may offer their flavor and aroma in the form of lemon, tangerine, and/or grapefruit. The difference results from the varying limonene chemical forms that exist in the strains.
Other Plants Besides Cannabis with High Contents of Limonene
Limonene is not only found in abundance in cannabis strains. Plants like cloves, lemons, orange, juniper, peppermint, oregano, rosemary, cardamom, and pine also contain limonene.
Limonene in Nature
Limonene is a natural adaptative constituent of plants and is used to prevent predators and insects from invading them. This is because the emitted scent will make these predators and insects disinterested in feeding on them.
This adaptative feature is the reason why limonene (or any other dominant terpene) in a plant can be easily smelled.
Chemical Structure
Terpene is a hydrocarbon (carbon and hydrogen element only) compound with a colorless and odorless appearance in its liquid form. The molecular formula of the terpene limonene is C10H16.
The chemical structure of limonene has a chiral center, making it exist in two forms called enantiomers ― (R)-limonene and (S)-limonene. The (R)-limonene is the one with the orange aroma and flavor while the (S)-limonene is characterized by the lemon aroma. That is why oranges contain about 95 percent of (R)-limonene while lemon (S)-limonene dominates the lemon peels.
D-Limonene vs. L-Limonene
Based on optical activity, limonene can be classified into D-Limonene and L-Limonene. Both of them have the same chemical formula, but differ in their structure. D-Limonene is the most abundant type of the limonene compound and can be found in large concentrations in the essential oils of citrus fruits.
L-Limonene, on the other hand, can be found in pine and usually effuses a turpentine aroma.
Other Chemical Names for Limonene
In case you check a product advertised for its limonene content and discover the name is not similar to what you are familiar with, here are some limonene synonyms:
- Dipentene
- D-Limonene
- DL-Limonene
- Cinene
- 138-86-3
- Kautschin
- Unitene
- alpha-Limonene
- Flavor orange
- Orange flavor
- Goldflush II
- Acintene DP
- 1-Methyl-4-(1-methylethenyl) cyclohexene
- Limonène
- Limoneno
Effects of Limonene
Limonene is popular for its energizing and mood uplifting high that can at the same time relieve stress. It can also facilitate the absorption of other terpenes into the body via the skin, digestive tracts, and mucous membranes.
How it Works
Just like the research on other major cannabis terpenes, there is a need for more research on limonene interaction with the body system, most notably with the brain. The few research studies used high doses of the terpene, which is higher than normal in marijuana strains. This is why such research may not be valid for cannabis users but instead applicable in supplement users.
Medical Benefits of Limonene
Limonene terpene does not only offer recreational effects. Research studies have discovered it may contain some medical potency, which has led to many manufacturers extracting the terpene and selling it as a supplement. However, for cannabis lovers that prefer limonene-rich strains, below are some of the health benefits you may enjoy after consumption:
- Enhanced weight loss
- Protect against/treat cancer
- Treat gastrointestinal diseases such as acid reflux
- Cure respiratory complications
- Relieve heartburn
- Alleviate anxiety
- Cure fungal infections
- May ameliorate chronic liver disease
Scientific Researches
So far, there have been limited scientific studies conducted on limonene, but the unveiled potentials are worthy of interest.
- Anti-Inflammatory Property
A research study examining the effect of limonene discovered it controls inflammation in rat colitis, and at the same time prevents the development of inflammation in humans.
The University of Paris researcher concluded; “d-Limonene indeed demonstrates significant anti-inflammatory effects both in vivo and in vitro.”
- NAFLD Cure Potential
A research study conducted by Indian researchers and published in 2012 suggests the possibility that d-limonene may hinder the progression of metabolic syndrome associated with nonalcoholic fatty liver disease (NAFLD).
- Weight Loss
A research study using young Wistar rats fed with high-fats of 42.2 percent beef tallow for 8 weeks, after which 2 percent d-limonene was administered for 2 weeks, discovered a significant increase in fasting blood glucose.
- Cancer Treatment
There have been numerous research studies suggesting the anti-cancer properties of limonene. A study extracting limonene from orange peel discovered it significantly reduces skin carcinoma.
Another study also tested its effect on breast tumors and reported it showed considerable improvement. However, a study conducted in 1994 suggested limonene achieves such potency by initiating cellular redifferentiation.
A study that checked its effectiveness on induced skin tumor also detailed a positive report. The researchers suggested limonene is able to effect such potency due to its anti-inflammation, anti-oxidative, and Ras-signaling properties.
- Immunomodulatory Activity
Researchers in the Department of Biology at Lebanon Valley College published a study 2012 that concluded that limonene contains immunomodulatory compound for therapeutic or commercial purpose. Immunomodulatory property of a compound signifies the ability of the compound to affect the immune system function. The researchers advise against the administration of d-limonene in high doses because it may cause the death of t-lymphocytes, which are cells of the immune system.
- Weight-Loss Potential
A study revealed limonene can significantly reduce the blood sugar level while another study has also discovered that terpene limonene aroma can reduce appetite.
Usage Safety and Side Effects
The toxicity of limonene is significantly low. It is listed Generally Recognized As Safe (GRAS) flavoring agent in the Code of Federal Regulations (21 CFR 182. 60) by the Food and Drug Administration (FDA). However, there have been some initially conducted studies that indicate limonene may increase chances of renal tubular tumors development in male rats. Subsequent studies, though, prove it is not harmful for human use.
The side effects observed in humans are:
- Pain
- Skin irritation
- Nausea
- Vomiting
- Diarrhea
To avoid any complication, limonene is advised not to be used along with certain medications.
- Limonene may enhance the liver metabolism of some medications. Therefore, avoid medication that might be changed by the liver, including diclofenac (Cataflam, Voltaren); ibuprofen (Motrin); meloxicam (Mobic); and piroxicam (Feldene); among others.
- Any medication that hinders the breakdown of another medication in the liver should be avoided. This is because they might decrease the breakdown of limonene in the liver and thus increase the effects and side effects of limonene. These drugs include cimetidine (Tagamet); fluvoxamine (Luvox); omeprazole (Prilosec); ticlopidine (Ticlid); and topiramate (Topamax).
- Medication that increases the breakdown of another medication in the liver should also be avoided because it may hasten the breakdown of limonene in the liver and therefore cause a reduction in the limonene effect. They include carbamazepine (Tegretol); prednisone (Deltasone); and rifampin (Rifadin/Rimactane).
Pregnant and breast-feeding mothers are advised to stay away from the usage of substances containing limonene because of insubstantial information about the effects of its high dose.
Usage in Aromatherapy and other Industries
Limonene is widely used in food and drug production; as a fragrance in the cosmetic industry; and as constituents of detergents and biodegradable domestic degreaser in the cleaning industry. There is also evidence of its use in biotechnology.
Because it is a monoterpene, it is used as a precursor for the synthesis of other substances, such as p-cymene, using catalyzed dehydrogenation.
It is also used as a base compound of insecticides, which are effective against ants, aphids, and other insects/pests.
Limonene has also found its way into the printing industry as it is now used for 3D printing.
Limonene-Dominant Strains
Cannabis strains heavily effusing citrus are more likely to be limonene-dominant. Some people believe this characteristic is usually associated with sativa strains, but data analysis has revealed it is equally present across the different cannabis strains (indicas, sativas and hybrids). There are some strains that smell nothing like citrus but yet are limonene-packed.
Some of the strains reported to be rich in limonene include:
- Super Lemon Haze
The super lemon haze is a sativa-dominant and two-time cannabis cup winner. Its lemon taste is assumed to be the reason its breeder included “lemon” in its name. The strain is advisable for use during daylight as it gives you an energetic and heightened focus effect, which may prevent sleep.
Recommended for relieving stress, treating pain, and depression.
- OG Kush
First cultivated in Florida in the ’90s and arrived in Los Angeles in 1996, OG Kush is popular for its relaxing but yet euphoric effect. It may not hinder your normal daily activities after consumption.
Best for treating depression and insomnia as well as relieving stress.
- Durban Poison
The sweet smell of this South African breed pure sativa strain is not easy to conceal anywhere it is placed. It is known for its energetic and focused effects that are best for use whenever you do not want to sleep but instead want to get a lot of tasks done.
Recommended for treating depression, stress, and lack of appetite.
Other marijuana strains with high limonene content include:
- Jack Herer
- Dirty Girl
- Lemon G
- Blob OG
- Cinex
- Cookies and Cream
- Emerald Jack
- Liberty Haze
- Original Glue (GG4)
- Mazar x Blueberry
People specifically in search of CBD-dominant strains may try:
- Sour Space Candy Hemp Flower
This marijuana strain is richly packed with about 16.28% CBD. Its terpene profile includes: alpha-Pinene (0.04%), beta-Myrcene (0.36%), Limonene (0.05%) and Linalool (0.02%).
Recommended for treating chronic pain, inflammation, anxiety, and stress relief.
- Elektra Hemp Flower
Elektra contains about 15.91% CBD. It is the offspring of the widely available CBD-packed strain, ACDC. Its terpene profile includes alpha-Pinene (0.06%), beta-Myrcene (0.34%), Linalool (0.02%), and Limonene (0.05%).
Recommended for treating pain and inflammation.
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