A Search for Santonin in Artemisia pontica, the Other Wormwood of Old Absinthe Wilfred N. Arnold1 and Timothy P. Dalton Department of Biochemistry, University of Kansas Medical Center, Kansas City, KS 66103 Loretta S. Loflus Department of Medicine, University of Missouri-Kansas City School of Medicine Patrick A. Conan Chaire d'Histoire de ia Medecine et de la Chirurgie, Universite Paris VI, Paris, France Ahsinthe was a green liqueur that enjoyed great popularity during the latter half of the 19th century and the beginning of ours (I).In France, l'heure uerte, the green (cocktail) hour, was an established daily event, and some Parisian clubs were dedicated to the drink. The "Old Absinthe House" in New Orleans dates from the same era. The liaueur was noted for hiah concentrations of both alcohol i d essential oils. ~ l t h o u g the h number and proportions of herbs varied with each manufacturer, they always included wormwood (Artemisia absinthium), ~ o m wormk wood (Artemisia pontica), anise, and fennel ( 2 ) .Upon dilution of absinthe with water (a ritual involving dropwise addition over a cube of sugar mounted on a special spoon), the terpenes precipitated as a colloidal suspension and produced a yellowish opalescence (louche) that contributed to the general mystique and enthralled artists and poets. The essential oils also contributed to the liqueur's flavor, fragrance, and toxicity. Auguste Motet, a French physician, attested to the daneers of excessive imbibition of absinthe as earlv as 1859. ~ u t w q u e n investigators t implicated and eventuaily defined the ootentiallv iniurious romoounds in addition to ethanol. coined the teim ;absinthismi' for the syndrome presented by addicts, and recommended government interdiction. However, because of profits and taxes enjoyed by manufacturers and the state respectively, plus skepticism by consumers, the liqueur was not banned in the United States, France, and elsewhere until the 20th century. The most
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deleterious constituent proved to be thujone, a dicyclic ketone whose structure was elucidated by Semmler (3)in 1900; the primary source of thujone in absinthe was wormwood. After the ban on "old" absinthe a substitute pastis with no wormwood hut additional anise was offered on the continent under proprietary names such as Ricard and Pernod. Old ahsinthe affected many creative people, not least of which Vincent van Gogh, whose congenital illness was exacerbated by excessive, episodic consumption of the drink; his fits with hallucinations are now thought to he largely due to exposure to thujone (4). One intriguing aspect of this highly innovative artist was his adoption of a yellow palette, that is t o say a dominance of the yellow region of the spectrum is recognizable in several of his paintings from 1886 until his suicide in 1890. Some authors have supposed that he suffered from a visual aberrancy, possibly a modification of color vision. Chromatopsias are usually reversible but would change one's view of the world and might impress an artist for later rendition on canvas after return to normal color vision. Lee (5) and others speculated that van Gogh had a xanthopsia (yellowvision) due specifically to digitalis intoxication. The medical aspects are well documented, but the evidence of van Gogh's exposure to the drug rests solely upon his incorporation of a sprig of foxglove into the two portraits of Dr. Gachet (18901, which we are more inclined to interpret as a symbol for the physician rather than a drug for the artist. Nevertheless, we though it worthwhile to explore other chemicals that can induce xanthopsia. A classical example is santonin, a sesquiterpene lactone that is found in several Artemisia species hut was commercially exploited from A. maritima (6). Santonin was used effectively as an anthel-
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mintic for over 100 years. I t has been displaced by equally effective drues that have less side effects. The structure of santonin CIj H 1 ~ 0isi shown in the figure; it crystallizes from alcohol or wateras flat hexagonal prisms, m.p.171-172 OC: it is an unsaturated ketonic lactone and has a molar extinction coefficient of 11,230 a t 236 nm (6). The classical method of isolation involved extraction of dried Artemisia sp. with chloroform, formation of a barium salt, precipitation of the lactone by acidification, and crystallization from ethanolwater(7). Disturbances of vision follow overdosage with santonin. According to Marshall (8) a single dose of 0.2 g will induce yellow vision after 2 h; 0.5 g will induce greenish yellow vision in a half hour. The question arose, was there any santonin in old absinthe? Was there anv chance that a binee on absinthe could result in an episode of xanthopsia for van Goeh? An analvsis of 19th-centuw absinthe would provide th'answer b u t b a s not available. However, we can examine the recipe for Absinthe Suisse de Pontarlier (91,which is summarized as follows. Dried, finely divided, and measured amounts of wormwood, anise, and fennel are steeped in 95 L of 85% ethanol overnight; additional water is added; and then the mixture is subjected to a simple pot distillation; 95 L of distillate are collected. Because of the relatively low volatility of santonin, we would not anticipate the lacrone in the diatillate even if oresent in the orieinal herbs. This was confirmed in the laboratory with a sample of pure santonin dissolved in 85% alcohol and subiected to oot distillation. None of the four fractions collecied a t 78k82.0 O C contained any santonin (method described below); the succeeding fraction boiling at 82.0-89.0 OC contained a trace; more was present in the next fraction a t 89.0-98.5 'C but represented but 2% of the original concentration. Santonin crystallized in the pot upon cooling as fine white crystals. The only reference (10) we could find to santonin in Artemisia absinthium indicated that i t was not a commercially feasible source: toeether with our result on the simulated distillation. we can excuse the herbs of the primary distillate from con: tributin~santonintoahsinthe. But the Pontnlier recine calls for an additional extroclion step, involving Arlern~siopontico. to urovide additional flavor and areen coloration. ~ i f t ~ l f i liters v e of the primary distifiate are put aside, and ~
to the remaining 45 L are added 1kg dried (cf. 5 kg wet wt) Roman wormwood (Artemisia pontica), some hyssop, and melissa (9).After extraction at a moderate temperature the plant material is removed by filtration, and the liquor, now green and enriched with the alcohol-extractables of the secondary herbs, iscombined with the other 55-Lportion. Some water is added to achieve approximately 100 L of absinthe a t 74% alcohol by volume. So the remaining question is about A. pontica and santonin; if present, it would certainly be subject to alcohol extraction. An extensive search of the literature on this species revealed anumber of papers on the essential oil of A. pontica but nothing on santonin from this species. Three small seedlings of Roman wormwood were obtained from a Maine dealer and grown in the Kansas City area. In early fall, 70 g of the above-ground parts of A. pontica were thoroughly extracted with 500 mL warm, 85% ethanol, filtered, and stored in the cold. A sample (25 mL) of the clear, green extract was taken to dryness at 40 'C, resuspended in absolute ethanol, dried, resuspended again in alcohol, dried, and then extracted with 5 mL chloroform. This solution was cleared by centrifugation and taken to dryness; the residue was extracted with 5 mL 95% (vlv) aoueous acetonitrile and nassed throueh a small column of (Sep-Pak, waters ~ssociat&).A sample of the effluent was adiusted to 40% acetonitrile and centrifueed. IA control experiment indicated that authentic santonk ( ~ 1 drich Chemical) was recovered in good yield by processing through all of the above steps.] A 10-pL sample was subjected to HPLC on Clnsilica (w Bondapak, Waters) with 40% acetonitrile as mobile phase (isocratic development); the effluent was monitored a t 236 nm. A companion sample was spiked with 60 ng santonin, which resulted in only one change, an increase in the peak emerging a t 6.8 min. Based uoon areas under the curve the A. oontica extract was estimated to contain a t most 56 ng santonin per 10pL of applied samnle. i.e.. assumine that this peak represented onlv santonin.'~djustments based upon*diluti& and concentration factors durine ~rocessinevielded an estimate of 22 .ue santonin per gramwet weighcif A. pontica. One liter of absinthe contained the alcohol-extractables from 50 g wet weight of A. pontico. This would have contained, at most. 1.1 mg santonin according to our simulated preparation and analysis. In order to induce xanthopsia, due to the santonincontent of absinthe prepared in this manner, one would have to consume 182 L. i.e.. to eet a dose of 0.2 e. W;are inclined to dismiss the phssibilit; of xanthopsia in van Goeh or anvother ahsinthedrinker due to santonin from that soiree. "
silica
Literature Cited
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Journal of Chemical Education
.; L ~ ~ , T . ' Jc . Am. Med. Assn. 1981.245,72i 6. Sirnomen, J. L.T h e Tarmnes: Cambrace Univ: Carnbridpe, 1949: Yo].2 7 . Couttr,J. Phorm. J . ~ h & 1929.123.603. 8. Marshall, W.A.J.Phoimaeo1, Erp. Thrr. 1927,30,361. 9 D d a i s . P. Tmite de8 Liaueur. Chez L'Auteur: Paris. 1855
