A while ago I came across the article “Christmas gingerbread (Lebkuchen) and Christmas cheer–review of the potential role of mood elevating amphetamine-like compounds formed in vivo and in furno” (abstract from NCBI, free full text pdf download from publisher). The paper reviews a hypothesis proposed by Alexander Shulgin in a series of papers appearing in Nature in the 60′s. Shulgin noted that allylbenzenes and propenylbenzens found in many spices are “merely lacking ammonia to become amphetamines”. The author reviews the evidence that such substances may be converted in the body to psychoactive metabolites, but concludes that the evidence is equivocal at best. However, the author launches an alternative theory:

“… the formation of these compounds during the cooking process, what I have called “in furno.” Examination of the Lebkuchen recipe in Table 3 reveals chemical constituents that, when heated together in furno might plausibly result in some ammonia addition to the alkenylbenzene double bonds, which would lead to the presence in the Lebkuchen of 4-methoxyamphetamine (PMA) from (E)-anethole and 4-hydroxy-3-methoxyamphetamine (HMA) from eugenol.”

But as the author prudently add: “Until the appropriate laboratory and clinical investigations are performed, it is merely a subject of speculation and fantasy.” Nevertheless is an entertaining paper to read, and I’m sure that this kind of “science triva” can cheer up discussions around the dinner tables in an otherwise dark December. And I must add that I really love the term in furno (i.e. in the oven, during the cooking/baking process) used alongside the more common in vivo and in vitro.

I’ve illustrated the proposed reactions in the scheme below. Anethole and eugenol are found in cloves/cinnamon and anise seeds respectively. Baker’s ammonia is known to chemists as ammonium carbonate, but also under names such as salt of hartshorn. It has a very strong smell of ammonia and upon heating it decomposes and releases ammonia which could possibly react with the allyl/propenyl groups.

[Found via the very funny NCBI ROFL blog]