Wormwood

Scientific Name(s): Artemisia absinthium L. Family: Asteraceae (daisies)

Common Name(s): Wormwood , absinthium , armoise , wermut , absinthe , absinthites , ajenjo , pelin otu , aci pelin , ak pelin , buyuk pelin , vilayati afsanteen 1 , 2 , 3 , 4

Clinical Overview

Uses of Wormwood

Traditionally, wormwood was used to treat worm infections, although research reveals no clinical data regarding the use of wormwood for any condition. Anti-inflammatory, antifungal, and antipyretic activity have been documented in vitro or in animal models. Wormwood also is used as a flavoring agent.

Wormwood Dosing

There is no recent clinical evidence to support dose recommendations for wormwood. Its classical use for dyspepsia was at a dose of 3 to 5 g for infusion daily or 2 or 3 g daily as the herb. Use caution because the thujone content of wormwood varies widely.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Avoid use because of documented abortifacient and emmenagogue effects.

Wormwood Interactions

The thujones in wormwood may reduce the clinical efficacy of phenobarbital by lowering the seizure threshold.

Wormwood Adverse Reactions

Thujone produces a state of excitation and is a powerful convulsant. Ingestion of wormwood may result in neurologic symptoms known as absinthism, a syndrome characterized by digestive disorders, thirst, restlessness, vertigo, trembling of the limbs, numbness of the extremities, loss of intellect, delirium, paralysis, and death.

Toxicology

Wormwood is classified as an unsafe herb by the Food and Drug Administration (FDA) because of the neurotoxic potential of thujone and its derivatives. The safety of wormwood is poorly documented despite its long history of use as a food additive.

Botany

Wormwood is an odorous, perennial shrub native to Europe and naturalized in the northeastern, central, and northwestern United States. Its aromatic leaves and multibranched stems are covered with fine, silky hairs. The plant grows to a height of about 1 m, and its small flowers are green-yellow. The deeply lobed leaves are grayish-green in color. 1 , 2

History

The name wormwood is derived from ancient use of the plant and its extracts as an intestinal anthelmintic. In Pakistan's indigenous medicinal systems, the leaves and flowering tops are used as an anthelmintic, antiseptic, febrifuge, stomachic, and to alleviate chronic fever, dyspepsia, and hepatobiliary ailments. Extracts of the plant are used as a bitter seasoning for food and added to drinks such as beer, tea, or coffee. In western European traditional herbal medicine, wormwood was recommended for gastric pain, cardiac stimulation, and for the restoration of declining mental function. In traditional Chinese medicine, practitioners treated acute bacillary dysentery by applying fresh and dried plants of absinthium. A poultice of the plant has been used medicinally for tendon inflammation. A tea of the plant was used traditionally as a diaphoretic. 4 , 5 , 6 , 7

Wormwood extract is the main ingredient in absinthe, a toxic liquor that induces a syndrome known as absinthism, characterized by addiction, GI problems, auditory and visual hallucinations, epilepsy, brain damage, and increased risk of psychiatric illness and suicide. The drink has been banned in several countries, but in the 19th century, absinthe-based liquor was known for its aphrodisiac and healing properties, and also was reputed to stimulate creativity. The emerald green color of absinthe liquor came from chlorophyll; however, copper and antimony salts were reportedly added as colorants to inferior batches, with toxic consequences. Thujone-free wormwood extract is currently used as a flavoring, primarily in alcoholic beverages such as vermouth. 2 , 8 , 9

Chemistry

The medicinal or active components in wormwood are the essential oils, anabsinthin, absinthin, resins, and organic acids. The bitter taste of wormwood is caused by the glucosides absinthin and anabsinthin, and several related compounds. 2 , 10

Lactones include arabsin, artabin, ketopelenolide, and others related to santonin. 1 An important isolated flavonoid is 5,6,3′,5′-tetramethoxy 7,4′-hydroxyflavone (p7F). 11

Many Artemisia species contain monoterpene-thujone derivatives that have toxic effects on the CNS. Wormwood typically contains small amounts of thujone derivatives, including 0.2% (Z)-thujone and 0.5% (E)-thujone 2 , 3 ; however, the thujone content varies widely. 12

The major components of wormwood oil include chamazulene (17.8%), nuciferol butanoate (8.2%), nuciferol propionate (5.1%), and caryophyllene oxide (4.3%). The essential oils also contain a large amount of aromatic compounds (40.9%) and a low level of oxygenated monoterpenes (23.5%). The plant contains a pleasant-smelling volatile oil (about 1% to 2% by weight) as well as phellandrene, pinene, azulene, and more than 6 other minor components. 8 Flowers may contain oil composed of up to 35% thujones. Cis- and trans-epoxyocymenes account for up to 57% of the volatile oil derived from Italian absinthium. 1 , 8

Wormwood also contains trace amounts of thymol and carvacrol as well as other phenolic compounds with potent antioxidant and radical scavenging activity. 3

Wormwood Uses and Pharmacology

The scientific literature contains mostly phytochemical, ethnopharmacology, and ethnobotanical investigations, with little clinical investigation of wormwood.

The anthelmintic activity of the plant is thought to be caused by lactones related to santonin, found in wormseed and other species of Artemisia . In addition, thujone can stun roundworms, which can then be expelled by normal intestinal peristalsis. 1 , 8

An ethnobotanical and ethnopharmacological study documents the use of wormwood in humans for treating intestinal worms in Dominica, West Indies. 13

A similar study of plants in central Italy documents some veterinary practices utilizing the plant as an antihelmintic for cows. 14

Hexane-, chloroform-, and water-soluble extracts of A. absinthium exhibited antipyretic activity against subcutaneous yeast injections in rabbits. No toxic effects were documented for the plant extract at doses up to 1.6 g/kg. 15

The essential oils distilled from the aerial parts of A. absinthium inhibited the growth of Candida albicans and Saccharomyces cerevisiae var. chevalieri . 16

pF7, a flavonoid isolated from A. absinthium , has antioxidant activity and inhibited nuclear factor-kappaB (NF-kappaB activation). The regulatory functions of pF7 were examined on the production of nitric oxide (NO), prostaglandin (E2 and PGE2), tumor necrosis factor (TNF-alpha), and expression of nitric oxide synthase (iNOS), cyclo-oxygenase-2 (COX-2), and collagen-induced arthritis. The production of COX-2, PGE2, iNOS, and NO in lipopolysaccharide-stimulated RAW 264.7 cells was inhibited by pF7. pF7 also suppressed TNF-alpha activity and inhibited NF-kappaB. 11

A. absinthium has been studied for cognitive enhancement because of its nicotinic and muscarinic receptor activity (IC ₅₀ concentration of less than 1 mg/mL) in homogenates of human cerebral cortical membranes. 17 The intoxicating effects of thujone were believed to activate receptors responsible for marijuana intoxication; however, thujone exhibited low affinity for rat cannabinoid receptors. 18 Methanol extracts of A. absinthium enhanced neurite outgrowth induced by nerve growth factor (NGF) and PC12D cells. 19

Dosage

There is no recent clinical evidence to support dose recommendations for wormwood. Its classical use for dyspepsia was at a dose of 3 to 5 g for infusion daily or 2 to 3 g daily as the herb. Use caution because the thujone content of wormwood varies widely. 12

Pregnancy/Lactation

Avoid use because of documented abortifacient and emmenagogue effects. 20 , 21

Interactions

The thujones in wormwood may reduce the clinical efficacy of phenobarbital by lowering the seizure threshold. 22

Wormwood has a hepatoprotective action against acetaminophen and CCl ₄ -induced liver toxicity in rats and mice. The mechanism of action may be associated with inhibition of hepatic microsomal drug metabolizing enzymes, antioxidant activity, and/or blocking calcium channels. 4

Adverse Reactions

Thujone produces a state of excitation and is a powerful convulsant. Ingestion of wormwood may lead to a constellation of neurologic symptoms described as absinthism. The syndrome is characterized by digestive disorders, thirst, restlessness, vertigo, trembling of the limbs, numbness of the extremities, loss of intellect, delirium, paralysis, and death. 2 , 20

The oil is used as an ingredient in rubefacient preparations; flowers may induce topical eruptions in sensitized persons. 23

Toxicology

A 31-year-old man suffered convulsions after drinking 10 mL of essential oil from wormwood or A. absinthium . The patient mistakenly assumed the essential oil was actually absinthe liquor and consumed the 10 mL full strength. The seizure was believed to be caused by the essential oil of wormwood, which also led to rhabdomyolysis, renal failure, and congestive heart failure. The patient recovered and laboratory parameters returned to normal after 17 days. 24

Wormwood is classified as an unsafe herb by the FDA because of the neurotoxic potential of thujone and its derivatives. Few studies document the safety of wormwood despite its long history of use as a food additive. Thujone bears a superficial structural resemblance to camphor, pinene, anethole, and citral. 25

In a 13-week, dose-toxicity study in rats, convulsions were observed in rats given thujone in concentrations as low as 25 mg/kg/day. An increase in mortality was shown in rats given 50 mg/kg/day. 26 Other studies document a dose of 120 mg/kg as fatal, including a subcutaneous LD ₅₀ of thujone in mice as 134 mg/kg. 9 , 13 , 27

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