Posted on 06/04/2013 11:31:53 PM PDT by neverdem
The supramolecule mimics the structure of haemoglobin (below) with iron(III) at it's centre © Wiley-VCH
Japanese researchers have created a supramolecule that binds to cyanide ions in a similar way to the blood protein haemoglobin. This could pave the way for faster, more effective cyanide antidotes.
The effects of cyanide poisoning are well known to fans of spy stories and murder mysteries. It rapidly shuts down respiration, and high doses can kill in a matter of minutes. Every year, industrial accidents result in several cases of cyanide poisoning, and there is growing concern that it could be used in a terrorist attack. Unfortunately, existing antidotes are slow to act and often ineffective.
Nitrite antidotes, for example, work by oxidising the iron in the poisoning victim’s haemoglobin. This transforms it into a form called methaemoglobin, which has a high binding affinity for cyanide, and removes it from the site of action. But this is a slow process, with harmful side effects. Koji Kano and colleagues at Doshisha University in Kyoto, Japan, have managed to speed things up by constructing a cyanide-binding supramolecule that mimics methaemoglobin. The complex, Met-hemoCD3, consists of an iron(III)-containing porphyrin held in a capsule of cyclodextrin dimers.
Haemoglobin can bind cyanide making it an obvious structure to try to copy to treat CN- poisoning © Shutterstock
Met-hemoCD3 binds to cyanide ions to produce non-toxic CN--met-hemoCD3, under conditions found in the human body. In vitro tests showed that it bound to cyanide faster than either methaemoglobin, or hydroxocobalamin, a widely used cyanide antidote. The team also tested its abilities as an antidote on rats that had been poisoned with sodium cyanide and it performed well. An intravenous infusion of Met-hemoCD3 successfully revived rats that had gone into respiratory arrest, while untreated rats died.
‘The rate of cyanide binding is fast, which is important for emergency therapy,’ says Kano. ‘And we found no evidence of toxicity.’ He adds that collaboration with medical doctors and industrial partners is now needed to bring Met-hemoCD3 into actual use.
But Gerard Boss, of the University of California San Diego, US, who is also working on novel cyanide antidotes, is unconvinced that Met-hemoCD3 will offer any real advantages. ‘The compound can function as a cyanide scavenger,’ he says, ‘but they have not compared it in vivo to currently available antidotes. All of their comparisons have been in vitro.’ He also argues that the real demand is for antidotes that can be administered via intramuscular injection, rather than intravenously, so large numbers of casualties could be rapidly treated following an accident or attack involving cyanide.
K Watanabe, H Kitagishi and K Kano, Angew. Chem., Int. Ed., 2013, DOI: 10.1002/anie.201302470
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Hydroxocobalamin?
Isn’t that just vanilla Vit B-12?
Is that possible?
Possible... just not sure if it’s true. B-12 is cobalamin, but takes different forms if it has a hydroxy (OH) attached, a methyl (CH3) group attached, who knows?
Yes, it’s a form of B-12, it will bind cyanide to become cyanocobalamin, and it is presumably detoxified by the liver at leisure.
http://en.wikipedia.org/wiki/Vitamin_B12
Pardon the above reference, but I didn’t read anything, although I just skimmed it, that contradicts what I’ve learned elsewhere in chemistry and medicine.
Vanilla Vit B-12, as opposed to Chocolate Vit B-12, Strawberry Vit B-12, or Rocky Road Vit B-12!
I guess! Sumthin like that, eh?
Er, can you clarify what exactly you believe contradicts what you’re learned elsewhere? Hydroxocobalamin is indeed used to treat cyanide poisoning.
Were you even responding to me?
Let me rephrase it. I wrote, "Pardon the above reference, but I didn’t read anything, although I just skimmed it, that contradicts what I’ve learned elsewhere in chemistry and medicine."
I didn’t read anything that contradicts what I’ve learned elsewhere in chemistry and medicine, although I just skimmed it.
Wikipedia is often ignored because it plays politics. When a subject isn't politicized, it can be a solid resource.
Were you even responding to me?
No, just offering a good reference.
My experience seems to be that the more technical the article, the cleaner it is.
For instance I was reading about “motor proteins” and it was very informative.
Not too many ways you can politicize motor proteins!
But I admit I ain’t got the gumption to go and try reading about “climate change”...
Sometimes the lunatics do indeed run the asylum!
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