Clove

Scientific Name(s): Eugenia caryophyllata Thunb. Family: Myrtaceae

Common Name(s): Clove , caryophyllus

Clinical Overview

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Uses of Clove

Clove has been used for its antiseptic and analgesic effects and has been studied for use in platelet aggregation inhibition, antithrombotic activity, and chemoprotective and antipyretic effects. However, research reveals little or no clinical data on the use of clove for any indication.

Clove Dosing

Clove oil is widely used to mask unpleasant olfactory cues; however, there is no recent clinical evidence concerning therapeutic doses.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Clove Interactions

None well documented.

Clove Adverse Reactions

Blood-tinged sputum and hemoptysis have been noted in clove cigarette smokers. Clove oil can irritate skin and mucous membranes.

Toxicology

Clove and clove oils are used safely in foods, beverages, and toothpastes. Toxicity has been observed following ingestion of the oil, but this rarely occurs.

Botany

The clove plant grows in warm climates and is cultivated commercially in Tanzania, Sumatra, the Maluku (Molucca) Islands, and South America. The tall evergreen plant grows up to 20 m and has leathery leaves. The clove spice is the dried flower bud. Essential oils are obtained from the buds, stems, and leaves. The dark brown buds are 12 to 22 mm in length with 4 projecting calyx lobes. The 4 petals above the lobes fold over to form a hood, which hides numerous stamens. The cloves are strongly aromatic. 1 The plant also is described as Caryophyllus aromaticus L. and Syzygium aromaticum L. Merr. and Perry.

History

Clove has a long history of culinary and medicinal use. The oil was used as an expectorant and antiemetic with inconsistent clinical results. Clove tea was used to relieve nausea. Use of the oil in dentistry as an analgesic and local antiseptic continues today. It also has been used topically as a counterirritant.

Chemistry

Clove buds yield approximately 15% to 20% of a volatile oil that is responsible for the characteristic smell and flavor. The stems yield about 5% of the oil, and the leaves yield about 2%. In addition, the bud contains a tannin complex, a gum and resin, and a number of glucosides of sterols. The principal constituent of distilled clove bud oil (60% to 90%) is eugenol (4-allyl-2-methoxyphenol). The oil also contains about 10% acetyleugenol and small quantities of gallic acid, 2 sesquiterpenes, 3 furfural, vanillin, and methyl-n-amyl ketone. 4 Other constituents include flavonoids, 1 carbohydrates, lipids, oleanolic acid, rhamnetin, and vitamins. 5

Clove Uses and Pharmacology

Eugenol possesses marked antipyretic activity in animals, similar to that of acetaminophen. 6

Research reveals there are little or no clinical data on the antipyretic use of cloves.

Sesquiterpenes from cloves reveal anticarcinogenic potential. 7 Similarly, eugenol present in clove oil may ameliorate effects of environmental food mutagens. 8

Whole cloves were chemoprotective against liver and bone marrow toxicity in mice. 9

Research reveals little clinical data on the anticarcinogenic properties of clove.

Research reveals no animal data on the use of cloves as a treatment for dental conditions.

Clove oil is applied for the symptomatic treatment of toothaches and is used for the treatment of dry socket (postextraction alveolitis). Studies indicate that techniques such as the application of collagen paste may be more effective than clove oil/zinc oxide preparations in the management of alveolitis. 10

Clove oil has antihistaminic and spasmolytic properties, most likely due to the presence of eugenyl acetate. 11 Cloves have a positive effect on healing stomach ulcers. 1 A 15% tincture of cloves is effective in treating topical ringworm infections. As with many other volatile oils, clove oil inhibits gram-positive and gram-negative bacteria. Its fungistatic action has been documented, suggesting use as an antidermatophytic drug. 12 Clove oil also has anthelmintic and larvicidal properties. Another report suggests clove oil suppresses aflatoxin production. 13

Eugenol in high concentrations can inhibit reactive oxygen species generated by macrophages during inflammation. 14

Aqueous extracts of clove increase trypsin activity. Eugenol inhibits prostaglandin biosynthesis, the formation of thromboxane B2, and arachidonic acid-induced platelet aggregation in vitro. This effect has been postulated to contribute to the antidiarrheal effect of other oils that contain eugenol (such as nutmeg oil). 15 Other reports confirm inhibition of platelet aggregation and antithrombotic activity of clove oil. 16 , 17

Dosage

Clove oil is widely used to mask unpleasant olfactory cues; however, there is no recent clinical evidence concerning therapeutic doses.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

None well documented.

Adverse Reactions

Clove oil can be a skin and mucous membrane irritant and sensitizer. 5 A case of a 24-year-old woman reports permanent local anesthesia and anhidrosis following clove oil spillage into the facial area. 18 Other case reports exist, including that of a 2-year-old child who experienced disseminated intravascular coagulation and liver failure following clove oil ingestion, 19 and another of a 7-month-old child who developed depression and electrolyte imbalance after accidental oral ingestion of clove oil. 20

Toxicology

Clove and clove oils are used safely in foods, beverages, and toothpastes. In general, the level of clove used in foods does not exceed 0.24%; the oil is not used in amounts greater than 0.06%. Toxicity has been observed following ingestion of the oil, but this type of poisoning is rare and poorly documented. In rats, the oral LD ₅₀ of eugenol is 2,680 mg/kg; however, the toxicity of the compound increases almost 200-fold when administered intratracheally (LD ₅₀ 11 mg/kg). 21 Increased toxicity by the pulmonary route has become more important in light of the toxicity reported among people who have smoked clove cigarettes. Clove cigarettes, called “kreteks,” generally contain about 60% tobacco and 40% ground cloves. More than a dozen brands of kreteks exist. They are popular in Asian countries, and their popularity is growing in the United States and Europe.

More than a dozen cases of pulmonary toxicity have been reported in people who have smoked clove cigarettes. 22 , 23 There is evidence that clove cigarettes may anesthetize the throat, leading to deeper and more prolonged inhalation of the smoke. Blood-tinged sputum and hemoptysis have been noted in smokers and may be related to eugenol's antiplatelet effects. 15 The American Lung Association has issued a warning against clove cigarette use, noting a higher tar content than ordinary cigarettes. However, one study found no carcinogenic effect of hot aqueous clove extracts in the Drosophila mutagenicity assay, although metabolites and pyrolysis products of eugenol are carcinogenic. 24

There has been no documentation of toxicity in the bud, leaf, or stem of the plant. 5

Bibliography

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