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By Robert H Olley | May 20th 2009 01:13 PM | 3 comments | Print | E-mail | Track Comments
About Robert H

I work in the Polymer Physics Group of the Physics Department at the University of Reading.

I would describe myself as a Polymer Morphologist

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Practically every month in my Chemistry World there appears an article where a group of workers has synthesized some natural product with amazing ingenuity. But why, to use a Hogwartsian analogy, does one go to such great effort when the greenhouse is only a walk away from the potions department? So let us join Professor Sprout for a walk around the Hogwarts greenhouses.

Some plant families, such as the Cruciferae and the Labiatae are remarkably free from poisonous plants, whereas others such as the Araceae all seem to come with a toxic hazard warning sign.

The Umbelliferae are generally benign (I think) and give us many useful herbs, but contain a few species which are among the most poisonous, including the hemlock that Socarates drank and the water dropworts Oenanthe which are among the most deadly plants in Europe, and still give rise to often fatal human poisonings.  (Wikimedia picture to right.)

This noxious herb has now found its place in the Potions Department through the researches of, among others, Mauro Ballero, Professor of Pharmaceutical Botany, School of Pharmacy, University of Cagliari (in the south of Sardinia). They haven’t got around to synthesizing the product yet, but they have isolated and characterized the active principle.



But who would use such a plant?  The villains of the piece appear to have been the Punics, among whom the most famous is Hannibal who came so near to destroying Rome (talk about a "Clash of Civilizations"!). But what is the evidence for this? According to the Italian news release

Greek poet Homer first used the word, an adaptation of the ancient word for Sardininan, to describe a defiant smile or laugh in the face of death.


He was believed to have coined it because of the belief that the Punic people who settled Sardinia gave condemned men a potion that made them smile before dying. The Punics were convinced that death was the start of new life, to be greeted with a smile.

Describing the background to their research, the team write [1]:

According to ancient historians, elderly people unable to support themselves were intoxicated with the herb and then killed by being dropped from a high rock or by being beaten to death.

The facial muscular contraction induced by the sardonic herb mimicked a smile, and the expression risus sardonicus (sardonic smile) to indicate a sinister smile is well documented in the Latin and Greek literature and in most modern European languages.

So that Sardonicism has come to mean the expression of derision, cynicism, or sceptical humour variously through comment, gesture, or writing.

The compounds isolated by the team are polyacetylenes, and one marvels at the chemical arms race that the plant must have had with its enemies to produce such a bizarre type of molecule in a living organism.






(picture from the abstract)


And is there anything in it for humans? This class of compounds has a unique capacity of dramatically perturbing calcium and sodium ionic currents in excitable membranes, and specifically interacting with ligand-gated ion channels like the  GABAA receptor. Risus sardonicus is most often observed as a sign of tetanus, and may also result from poisoning with strychnine. "The good news is that the molecule in this plant may be retooled by pharmaceutical companies to have the opposite effect," says Dr Ballero.

[1] Polyacetylenes from Sardinian Oenanthe fistulosa: A Molecular Clue to risus sardonicus
Giovanni Appendino, Federica Pollastro, Luisella Verotta, Mauro Ballero, Adriana Romano, Paulina Wyrembek, Katarzyna Szczuraszek, Jerzy W. Mozrzymas and Orazio Taglialatela-Scafati
Journal of Natural Products, Article ASAP: DOI: 10.1021/np8007717 http://pubs.acs.org/doi/abs/10.1021/np8007717



Comments

logicman's picture
Excellent!  What more can I say about this well researched and well written article?

Hank's picture
I have this issue a lot also.  I read so many things here where I know I got smarter but I don't have much to add beyond 'great article' so I just stay quiet.  But I guess we need to say it more often, because we really do have the best stuff here.

Robert -- Very nice! And thanks for the little note about carbonyl sulfide toxicity, intoxicated hawks and hard hats.
By the way, I notice that the weird polyacetylene toxins are 17 carbon dialcohols. Monoalcohols, starting with ethanol and ranging up to decanol, have anesthetic properties, and I seem to recall that they are postulated to act on the GABA receptor as well.
A side note -- has anyone figured out your logo yet? My guess is that it might be an electron micrograph of a fractured polymer surface that happened to resemble a crab. Am I even close?

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