Limonene is a neutral liquid hydrocarbon classified as a cyclic terpene. Limonene is the name that has been derived from the word lemon as it’s one of the major constituents seen in the rind of citrus fruits.

It is the Limonene in the rind that contributes to their odor. The more common d-isomer possesses a strong smell of oranges. The chief element of most citrus odor is (+)-limonene which can be up to 97% of the oil. It is in charge for the base sensory character of the citrus oils.

Limonene is a chiral molecule, and biological sources produce one enantiomer: the most important developed source, citrus fruit, contains D-limonene ((+)-limonene), which is the (R)-enantiomer. Racemic limonene is known as dipentene.

D-Limonene is retrieved for commercial purposes from citrus fruits through two primary procedures: steam distillation and centrifugal separation.  It is commonly used as base in producing cleaning product as a solvent; and is also used in chemical synthesis as a precursor to carvone.

Essential Oils with Limonene:

The few essential oils that contain Limonene are, Wild Orange (90% D-Limonene), Bergamot (30% D-Limonene), Lemon (70% D-Limonene), Grapefruit (92% D-Limonene) and Lime (65% D-Limonene)

Medicinal uses of Limonene:

The most important therapeutic uses of Limonene are:

Metabolism and Weight loss:

Appetite Control:

Limonene acts as a mild appetite suppressant, which can be used by individuals who are looking to curtail their appetite in case of diet plans or in nutritional requirements.

According to a study in 2002, limonene was seen to exhibit characteristics of  probiotics such as adjuvants , digestive enzyme inhibitors such as hibiscus tea,  marine algae, L-arabinose, Nomame Herba, inhibit glucose intake like phlorizin, and anorexics like monoterpenes such as perillyl alcohol, d-limonene.

This makes things a lot safer and easier for individuals looking to execute appetite control, as they can opt for the more natural, healthy option rather than to go in for lethal procedures.

Fatty Liver:

Limonene helps combat a fatty liver.  Limonene was included in the diet of animals that were regularly fed a high fat diet. The D-Limonene helped prevent the fat buildup resulting in a non- fatty liver seen in animals. It even showed signs of preventing insulin resistance.

According to a study in 2012, regular supplementation of D-limonene caused a reverse action on HFD and L-NAME-induced changes, and retuned pathologically damaged liver and pancreas to normal.  The study showed that it eased out insulin resistance and the effects of oxidative stress-induced liver injury in conditions of a fatty diet.

Anti- Inflammatory:

Limonene is a naturally found nutrient that helps manage inflammation. Limonene has potent antioxidant and anti-inflammatory properties and can be used on a daily basis as a routine health program. A study in 2010 suggests that “D-limonene may be considered a potential anti-inflammatory candidate.”

Antifungal & Antibacterial Properties:

Citrus oils are composed of monoterpenes, in particular D-limonene, which exhibit antibacterial and antifungal characteristics, and even inhibit the growth of certain parasites as well.

The 2016 study concluded that, “The mixture of oils containing limonene like most citrus oils, along with MgCl could be used as a natural antibacterial and anti-inflammatory agent”

Cytotoxic Properties:

Limonene is good for the body in general and should be a part of daily diet, exercise and a healthy lifestyle program toward the goal of reducing breast cancer risk.  The mechanism of benefit is not limited to breast cancer; researchers have proved that Limonene has anti-cancer properties for liver cancer, pancreatic cancer, gastric cancer, lung cancer, and prostate cancer.

D-Limonene Chemoprevention of Breast Cancer, a study conducted in the year 1994 suggested, “Usage of limonene was seen to decrease the development of mammary carcinoma, and also increased the dormancy period or carcinogenic cells. However the usage of Limonene did make much of a difference in the percentage of carcinomas with activated rats.”

Non- Medicinal uses of Limonene:

It is used as a botanical insecticide, the element d enantiomer is most active as an insecticide.

D-limonene is an alternative medicine that is marketed to relieve gastro esophageal problems and heartburn.

It is used as a fragrant alternative to turpentine, and also as a paint stripper.

Philatelists use air propellants, containing limonene to remove self-adhesive postage stamps from envelope paper.

It is also seen in all-natural commercial air fresheners.

Its ability to dissolve oils and its lemony fragrance makes it an important ingredient in cleaning products such as hand cleansers.

Limonene is obtained from a renewable source such as citrus oil and as a byproduct of orange juice manufacturing. It is extremely strong and hence it’s increasingly being used as a cleaning solvent to remove oil from machine parts, and in household cleaning as well.

Limonene is also frequently seen in cosmetic products such as aftershave lotions, masks, bath products, perfumery, and many other products as a flavoring agent.

Reference Links:

1. Limonene by Aromatic Plant Project
2. Limonene by Wikipedia
3. Dietary d-limonene alleviates insulin resistance and oxidative stress-induced liver injury in high-fat diet and L-NAME-treated rats, published in the European Journal of Nutrition and PubMed