Artemisia absinthium

Botany

A perennial herb of up to 1m high. The leaves are pinnately compound and silvery, grey green in colour, with deeply dissected leaflets(6). The stems and leaves are covered with fine, silky hairs(7). Numerous small, globular, pale yellow flower heads are borne along the branch ends(3, 6). Native to arid regions of Europe, North Africa(7) and Western Asia(8). Wormwood can also be found in eastern North America & Canada(7, 9). Main commercial supply is from eastern and south-eastern Europe(8). It grows in temperate regions worldwide(2).

History

The volatile oil of wormwood was used to make the drink absinthe, however the oil is toxic and most countries have banned its manufacture since the early 20th century(4, 7). The painter Vincent van Gogh was known to be consuming absinthe regularly, and many of his masterpieces where produced under the influence of absinthe(6). However a recent study evaluating if the thujone content of absinthe was responsible for the condition 'absinthism' (including symptoms of hallucinations, sleeplessness and convulsions), concluded that absinthe beverages of the 19th century comply with today's maximum limits and that thujone plays none, or only a minor role in the clinical picture of absinthism(10).

Major Active Constituents

The bitter taste of wormwood is from sesquiterpene lactones (0.15-0.4%)(1) - absinthin and artabsin being the main ones(3, 5, 6, 11) and guainolides(1). The essential oil (0.2% to 1.5%)(1) also includes -thujone (46%) and a small amount of -thujone (5), chrysanthenylacetate(3, 5, 6) and linalyl acetate (28%)(5). The concentration of the active constituents is seasonally & geographically different(12) and some genotypes are characterised by particularly high contents of active essential oil constituents(13).

Aromatic bitter(2, 4, 8, 14, 15), bitter tonic(3, 5, 9, 11, 16), anthelmintic(3, 5, 9, 11, 16), stomachic(9), antiparasitic(5, 11), antiseptic (GIT)(3, 16), choleretic(3, 4, 9), carminative(4, 16), anti-inflammatory(2, 16, 17), and mild antidepressant(2, 16).

The effectiveness of wormwood as an aromatic bitter and its antimicrobial properties come from the bitter compounds and its essential oil(6). Bitters are substances capable of strongly stimulating the bitter receptors in the taste buds at the back of the tongue and through reflex action (via the CNS) prime the upper digestive organs(18).

Antimicrobial
Antimicrobial screening performed on French origin A. absinthium oil inhibited the growth of both tested yeasts - Candida albicans and Saccharomyces cerevisiae var. chevalieri(19).

A comparison of various wild Artemisia species, found that A. absinthium from Western Canada had the strongest inhibitory affect against Staphylococcus strains (20).

Whole plant ethyl acetate and chloroform extracts of Artemisia absinthium inhibited some test micro-organisms (8-16 mm/20 ml inhibition zone). Methanol and acetone extracts showed no anti-bacterial effects. Of the 12 bacterial species and strains tested A. absinthium of either acetate or chloroform extracts inhibited the following bacterium; Bacillus brevis FMC 3, Bacillus megaterium DSM 32, Bacillus subtilis IMG 22, Bacillus subtilis var. niger ATCC 10, Mycobacterium smegmatus RUT, Escherichia coli DM, Staphylococcus aureus ATCC 25923, Streptococcus thermophilus, and Yersinia enterocolitica O:3 P 41797. Did not inhibit: luteus LA 2971 Listeria monocytogenes SCOTT A and Pseudomonas fluorescens(17).

Cholinergic receptor binding activity
Wormwood may have cholinergic activity. Ethanolic extracts of A. absinthium were screened for contents able to displace [3H]-(N)-nicotine and [3H]-(N)-scopolamine from nicotinic receptors and muscarinic receptors in homogenates of human cerebral cortical cell membranes. A. absinthium had IC50 concentrations of <1mg/ml. Choline, a weak nicotinic ligand was found in extracts of all plants studied at concentrations of 10-6 to 10-5 M. These concentrations could only account for no more than 5% of the displacement activity observed, suggesting there was more than just the activity of the choline ligand, binding with the nicotinic and muscarinic receptors(21).

Anti-pyretic
Significant oral antipyretic activity in rabbits was exhibited by hexane chloroform and water-soluble extracts of A. absinthium. Antipyretic activity was more prominent in the hexane-soluble portions of the plant. No toxic effects were noted for doses up to 1.6g/kg(22).

Hepatoprotective effects
An aqueous-methanolic extract of A. absinthium was tested on mice against Acetaminophen (paracetamol) and CCl4-induced hepatic damage. The extract showed hepatoprotective effects. Pretreatment of animals with plant extract (500mg/kg) reduced the death rate of acetaminophen liver damage from 100% to 20%. Pretreatment of rats with plant extract (500mg/kg orally twice daily for two days) prevented (p <0.01) the acetaminophen and CCl4 induced rise in serum transaminases. Post-treatment with three successive doses of extract (500mg/kg, 6hr intervals) restricted the hepatic damage induced by acetaminophen (p<0.01) but did not alter damage by CCl4 (p<0.05). The study also showed A. absinthium exhibits its hepatoprotective action partly through microsomal drug metabolizing enzyme inhibitory action(23). (500mg/kg twice daily for a 60kg human is 30g - 15-30 times the recommended daily therapeutic amount).

Thujone and increases in porphyrin
Chick embryo liver cells increased in the pigment pophyrin when thujone was introduced. It is suggested that thujone and affiliated terpenes may therefore be hazardous to patients with underlying defects in hepatic heme synthesis(24).

Bile and pancreatic secretion in man
Oral doses of liquid A. absinthium resulted in dramatic increase in duodenal levels of pancreatic enzymes and bile(11). Liquid preparations of A. absinthium stimulated gastric secretion in humans when it was given orally five minutes before a meal(18).

Clinical Outcome Studies

A double blind placebo-controlled multi-centre study (n=40) conducted in Germany on the steroid sparing effects of wormwood in Crohn's disease (CD) had a positive result. The study involved the tapering off of steroid (subjects stable on 40mg prednisone) from both placebo and wormwood groups until by week 10 all steroid use had been stopped. The treatment group received 3 times 500mg wormwood powder for these10 weeks (1.5g/day).

By week 10 (total cessation of steroid use) 65% of the wormwood group was almost in complete remission and there was no need to restart the steroid treatment in the following weeks (10wk post treatment follow-up). Also after the discontinuation of the wormwood treatment these same patients continued to remain in remission.

80% of the placebo group showed CD exacerbation and required steroid use during post-treatment period whereas this occurred in only 10% of the wormwood group.

Subjective feelings of illness in self-assessment (VA-Scale) was measured, there was no change in the placebo group, whereas the wormwood group indicated significant improvement.

The Hamilton Depression Scale (HAMD) was used and for the wormwood group the HAMD scores decreased by an average of 9.8 (SD 5.8) points and 3.4 (SD 6.6) in the placebo group. At the end of the acute phase treatment (wk 10) 70% of wormwood patients showed remission of depressive symptoms and none in the placebo group(25).

Anorexia(1, 3, 5, 9, 11, 14), indigestion, especially atonic dyspepsia(1, 3, 5, 9, 11, 14) (it acts both on the stomach and the gallbladder(4)), gastritis(4, 6, 8) and biliary dyskinesia(3, 4, 14). Worm infestation (nematode, pin or round worms)(3, 5, 9, 11).
General tonic effect, enhancing resistance especially for influenza, and weakness following infection(2, 4, 16). It is topically used to treat skin disorders, bruises and bites(6,17).

Contra-indications and Cautions

Pregnancy and lactation; wormwood acts as an emmenagogue and uterine stimulant(1, 2, 5, 24, 26). Contraindicated in lactation due to the potential toxicity of the essential oil of wormwood(5).

Hyperacidity; gastric and duodenal ulcers due to irritation of the stomach and stimulation of the gastrointestinal tract(1, 5, 11, 16, 26).

Thujone is a known CNS toxin(24), however, the toxicological risk from use of conventional wormwood preparations is very low(1, 4) and aqueous extracts contain little thujone(24, 27). Excessive dosing, long-term use or use of the essential oil could lead to toxicity(24). Side effects may include brain damage, convulsions, even death; insomnia, intestinal cramps, nausea, restlessness, seizures, stomach cramps, tremors, urine retention, vertigo and vomiting(1, 27).

Wormwood oil should not be used internally or externally as the thujone content is too excessive(27). Reported fatalities have been associated with ingestion of thujone in various essential oils, infusions and powders(27).

Sesquiterpene lactones have high allergenicity and occur commonly in the Asteraceae family(28). Wormwood use should be avoided where there is a known sensitivity to it or other members of the Asteraceae family (such as ragweed, daisies, and chrysanthemums)(5, 11).

Posology

Dried Herb
Most reputable sources recommend a range from 1-1.5g (1, 8, 9, 14, 16, 24) of dried herb as an infusion up to three times per day (maximum of 3g/day), for no longer than 3-4 weeks (after which time an aversion to the tea/preparations is likely to naturally occur(1, 4)).

In anorexia or as an appetite stimulant it is generally recommenced to dose half to one hour before meals(1, 6, 8, 18).

For dyspeptic complaints and as a cholagogue it is best taken warm after meals(1, 4, 6).

Tincture
Wormwood tincture or liquid extract is used less than the dried herb and is recommended for short term use(5). 5 to 20ml/per week (1:5) of liquid extract(3, 11), with the low end of the range for the bitter effect (5-10drops) and the higher end range, for a more direct effect on the gastric mucosa(18).

The tincture is useful during acute aggravation; 20-30 drops taken in ¨ù to ¨ö glass of water(4).

Powered herb as pills
Wormwood pills 0.1-0.2g/dose(4), however caution is required to avoid over-dosing (16). For Crohn's disease it is recommended to 1.5g/day (500mg pill three times a day)(25).

It is good to remember that bitters work best if sipped slowly, so the vagal reflex stimulation is prolonged. The strongly bitter taste (a bitter value of ¡Ã15 000 (14)) of wormwood may make this difficult for some patients(18).

References

1. Anonymous. 2003. ESCOP Monographs: The Scientific Foundation for Herbal Medicinal Products. 2nd edition. Exeter, U.K.: European Scientific Cooperative on Phytotherapy.

2. Chevallier A. 2001. Encyclopaedia of Medicinal Plants. St Leonards, NSW: Dorling Kindersley.

3. Thomsen M. 2005. Phytotherapy Desk Reference. 3rd edition. Michael Thomsen.

4. Weiss RF. 2001. Weiss's Herbal Medicine. 6th edition. Stuttgart: Thieme.

5. Mills S, Bone K. 2005. The Essential Guide To Herbal Safety. St Louis, Mo: Elsevier Churchill Livingstone.

6. van Wyk B-E, Wink M. 2004. Medicinal Plants of the World. Arcadia, South Africa: Briza Publications.

7. Swerdlow JL. 2000. Nature's Medicine Plants that Heal. Washington, D.C.: National Geographic Society.

8. Wichtl M (ed). 2004. Herbal Drugs and Phytopharmaceuticals: A Handbook for Practice on a Scientific Basis. 3rd edition. Stuttgart, Germany: CRC Press.

9. Anonymous. 1979. British Herbal Pharmacopoeia. West Yorks: British Herbal Medicine Association.

10. Lachenmeier D, Emmert J, Kuballa T, Sartor G. Thujone-cause of absinthism? Forensic Science International. 2006;158(1):1-8.

11. Bone K. 2003. A Clinical Guide to Blending Liquid Herbs. St Louis, Missouri: Churchill Livingstone.

12. Lachenmeier D, Walch S, Padosch S, Kroner L. Absinthe - a review. Critical Reviews In Food Science and Nutrition. 2006;46(5):365-77.

13. Nin S, Arfaioli P, Bosetto M. Quantitative determination of some essential oil components of selected Artemisia absinthium plants. Journal of Essential Oil Research. 1995;7(3):271-77.

14. Blumenthal M (ed.). 1998. The Complete German Commission E Monographs. Austin, Texas: American Botanical Council.

15. Schulz V, Hansel R, Blumenthal M, Tyler VE. 2004. Rational Phytotherapy: A Reference Guide for Physicians and Pharmacists. 5th edition. Berlin: Springer-Verlag.

16. Hoffmann, D. 2003. Medical Herbalism - The Science and Practice of Herbal Medicine. Rochester, Vermont: Healing Arts Press.

17. Erdogrul OT. Antibacterial activities of some plant extracts used in folk medicine. Pharmaceutical Biology (Formerly International Journal of Pharmacognosy). 2002;40(4):269-73.

18. Mills S, Bone K. 2000. Principles and Practice of Phytotherapy: Modern Herbal Medicine. London: Churchill Livingstone.

19. Juteau F, Jerkovic I, Masotti V, Milos M, Masterlic J, Bessiere J, et al. Composition and antimicrobial activity of the essential oil of Artemisia absinthium from Croatia and France. Planta Medica. 2003;69(2):158-61.

20. Lopes-Lutz D, Alviano D, Alviano C, Kolodziejczyk P. Screen of chemical composition, antimicrobial and antioxidant activities of Artemisia essential oils. Phytochemistry. 2008;69(8):1732-8.

21. Wake G, Court J, Pickering A, Lewis R, Wilkins R, Perry E. CNS acetylcholine receptor activity in European medicinal plants traditionally used to improve failing memory. Journal of Ethnopharmacology. 2000;69(2):105-14. [Abstract Online]. Available:EBSCO/Medline. [21 September 2008].

22. Khattak S, Gilani S, Ikram M. Antipyretic studies on some indigenous Pakistani medicinal plants. Journal of Ethnopharmacology. 1985;14(1):45-51.

23. Gilani A, Janbaz K. Preventive and curative effects of Artemisia absinthium on acetaminophen and CCl4 induced hepatotoxicity. General Pharmacology. 1195;26(2):309-15. [Abstract Online]. Available:EBSCO/Medline. [21 September 2008].

24. McGuffin M, Hobbs C, Upton R, Goldberg A (ed.) 1997 American Herbal Products Association Botanical Safety Handbook. Boston: CRC Press.

25. Omer B, Krebs S, Omer H, Noor T. Steroid-sparing effect of wormwood (Artemisia absinthium) in Crohn's disease: a double-blind placebo-controlled study. Phytomedicine: international journal of phytotherapy and phytopharmacology. 2007;14(2-3):87-95.

26. Brinker F. 1997. Herb Contraindications and Drug Interactions. Sandy, Oregon: Eclectic Institute.

27. Duke JA. 2002. Handbook of Medicinal Herbs 2nd edition. Boca Raton, Florida: CRC Press.

28. Myers S, Wohlmuth H. 2005. Allergic reactions to Herbal Medicines. In: Mills S, Bone K, editors. The Essential Guide To Herbal Safety. St Louis, Mo: Elsevier Churchill Livingstone.

This monograph was authored in 2008 by Zoe Sherrin, a student in Southern Cross University's Bachelor of Naturopathy programme, and edited by Nena Aleschewski BNat. While the author and editor have strived to cite published information accurately, Southern Cross University will not be responsible for any inaccuracies that may have occurred.

This information is provided for educational purposes only and does not constitute medical advice. If you wish to use herbal medicine as part of your health care, seek the advice of an appropriately qualified practitioner.