Tonka bean

Lamiaceae

Common Trade Names

Tonka Bean

Common Forms

Tonka bean is difficult to obtain commercially; availability is rare.

Source

Active components are extracted from the fruits and seeds of Dipteryx odorata, a tree that is native to South America, specifically Brazil and Venezuela. The tonka bean tree belongs to the legume family.

Chemical Components

The primary chemical components of tonka bean are coumarin, dihydrocoumarin, and o-coumaric acid. Other components include melilotic acid, methyl melilotate, ethyl melilotate, 5-hydroxymethylfurfural, fat, and starch.

Actions

Coumarin is metabolized within the body to 7-hydroxycoumarin, which then undergoes glucuronidation in the intestines and liver; this extensive first-pass metabolism results in a low absolute bioavailability of coumarin. Both coumarin and 7-hydroxycoumarin have inhibited growth of selected types of malignant human cell lines in vitro. The glucuronide metabolite of 7 -hydroxycoumarin appears to be inactive .

Reported Uses

Tonka bean is claimed to relieve abdominal cramps and nausea; the fruit is also thought to act as an aphrodisiac. It is known as a folk remedy for whooping cough as well. Coumarin has long been used as a flavoring agent in foods and a scent in pharmaceutical products. It has shown therapeutic benefit against lymphedema in clinical trials.

Dosage

The usual dose used is 60 mg of coumarin P.O. daily. (Some studies have based doses on the coumarin content of the product.)

Adverse Reactions

CV: potential cardiac effects (with large doses).

Hepatic: hepatotoxicity.

Interactions

Anticoagulants: May cause excessive bleeding. Avoid administration with tonka bean.

Drugs that cause hepatotoxicity: Risk of additive toxicity. Avoid administration with tonka bean.

Contraindications and Precautions

Tonka bean is contraindicated in patients with underlying hepatic dysfunction because of the potential for toxicity. Avoid its use in pregnant or breast-feeding patients; effects are unknown.

Special Considerations

Inform the patient that tonka bean is on the FDA's list of unsafe herbs.

Advise the patient to consult a health care provider before using herbal preparations because a treatment that has been clinically researched and proved effective may be available.

Monitor liver function test results.

Advise women to avoid using tonka bean during pregnancy or when breast-feeding.

Points of Interest

Do not confuse this herb with the synthetic anticoagulant bishydroxycoumarin.

Extracts of tonka bean have been used as a flavoring for castor oil preparations.

Commentary

Several tonka bean components, especialIy coumarin and 7-hydroxycoumarin, show promise as future therapeutic agents. Because efficacy and safety data are lacking, the herb cannot be recommended for any medicinal use.

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