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Calabar beans

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Gray
16565.  Thu Mar 24, 2005 11:56 am Reply with quote

Calabar beans (Physostigma venenosum) contain organic compounds called carbamates, which are toxic. Today they are used in pesticides.

Calabar beans were used in Africa as a way to determine whether someone accused of a serious crime, such as adultery, was innocent. Innocent persons would eat the bean quickly because they had nothing to hide. This quick consumption of the beans would induce the accused to vomit the bean, thereby expelling the bulk of the poison and he/she would live. Guilty individuals would be hesitant about ingesting the bean and would pick over them, slowly. The slow consumption of the bean would allow time for a lethal dose of the poison to be absorbed, and this person would die of rather unpleasant central nervous system damage.

Quote:
On the authority of the Rev. Mr. Waddell, a missionary at old Calabar, Dr. Christi-
son states that the general confidence of the African in the infallibility of the calabar ordeal test is so great that innocent persons accused of a crime often demand to be subjected to it, and thus pay the penalty of their blind superstition.


Source: here, and an interesting paper by one John Uri Lloyd!

 
Gray
16568.  Thu Mar 24, 2005 12:08 pm Reply with quote

The beans grow only around the Calabar River, in Nigeria, incidentally. Here, Mr Adebayo Lamikanra uses them to get across to the Niger Delta Congress the idea of 'burden of proof' to an educational and judicial system that he sees is lacking somewhat.
Quote:
And there the case must put to rest since the burden of showing proof lies heavily on the shoulder of the accuser rather than the accused. After all, ours is a very modern Judicial system and nobody can be condemned unless they have been proved to be guilty beyond a shadow of doubt. Indeed any doubt whatsoever must be resolved in favour of the accused. Still, I wonder just how quickly the senators would have swallowed their meal had they been confronted with a dish of Calabar beans rather than the earnest but unsubstantiated words of the Honourable Minister.

 
Frederick The Monk
16569.  Thu Mar 24, 2005 12:10 pm Reply with quote

Elixir of Calabar bean is an antidote to atropine (belladonna) poisoning and is recommended as a treatment of last resort in cases of chemical warfare attack using 3-quinuclidinyl benzilate. This chemical was one of those claimed to be in Iraq's famous arsenal of weapons of mass destruction. See here for more details

 
Gray
16578.  Thu Mar 24, 2005 1:04 pm Reply with quote

Which is ironic, as atropine is also a treatment for Calabar bean poisoning!
Quote:
In cases of poisoning by Calabar beans, the stomach should be evacuated, and atropine injected until the pulse quickens or the symptoms pass off.

 
Gray
16579.  Thu Mar 24, 2005 1:48 pm Reply with quote

As I remember, this sort of phenomenon is not uncommon for treating poisons - certain pairs of chemicals react and break each other down into non-poisonous compounds, and as long as you use the right amounts, you can recover fairly quickly. I'll check on this.

Unlike Homeopathy, of course, one of whose principles is that you use a little of the poinson to treat the rest of the poison. Obligatory Complementary Medicine thread required, although it brings me out frothing, frankly...

 
Frederick The Monk
16581.  Thu Mar 24, 2005 1:56 pm Reply with quote

I think the medical term for the physostigmine/ atropine relationship is 'antagonism'.

 
Sophie.A
609447.  Mon Sep 07, 2009 7:41 am Reply with quote

I’ve just read Agatha Christie’s Curtain: Poirot’s Last Case and was interested to note that the Calabar bean is mentioned and described in Chapter 7 of the novel.

Quote:
As far as I, a mere layman, could make out, Franklin was experimenting with various alkaloids derived from the Calabar bean, Physostigma venenosum. I understood more after a conversation which took place one day between Franklin and Poirot. Judith, who tried to instruct me, was, as is customary with the earnest young, almost impossibly technical. She referred learnedly to the alkaloids physostigmine, eserine, physovenine, and geneserine, and then proceeded to a most impossible-sounding substance, prostigmin or the demethylcarbonic ester of 3-hydroxyphenyl trimethyl lammonum, etc., etc., and a good deal more which, it appeared, was the same thing, only differently arrived at! …



As I say, any interest I could feel was kindled by Franklin’s conversation with Poirot.

He said:

“You know, Poirot, the stuff’s really more up your street than mine. It’s the ordeal bean – supposed to prove innocence or guilt. These West African tribes believe it implicitly – or did do so – they’re getting sophisticated nowadays. They’ll solemnly chew it up quite confident that it will kill them if they’re guilty and not harm them if they’re innocent.”

“And so, alas, they die?”

“No, they don’t all die. That’s what has always been overlooked up to now. There’s a lot behind the whole thing – a medicine man ramp, I rather fancy. There are two distinct species of this bean – only they look so much alike that you can hardly spot the difference. But there is a difference. They both contain physostigmine and geneserine and the rest of it, but in the second species you can isolate, or I think I can, yet another alkaloid – and the action of that alkaloid neutralizes the effect of the others. …

Later in the story, a character is killed after drinking coffee containing certain of the toxic alkaloids derived from the Calabar bean.

 

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