I always thought it was interesting knowing that the beautiful and wealthy woman of the past used “belladonna”, poison from the deadly nightshade plant, to make themselves seem more beautiful. Although the psychology behind why wide eyed woman are thought to be more attractive has always been interesting to me, I am most interested in the” whys” and the “hows” and the chemistry behind how their cosmetics actually worked. I have recently been listening to the “Chemistry in its element” a Chemistry World podcast series and whilst doing so I discovered in a short talk by Dan Johnson that the actual molecule behind this attractive pupil dilation is “atropine”.
Atropine looks a bit like this:
When in the body, Atropine inhibits “Acetylcholine” which is a neurotransmitter at neuromuscular junctions. This disrupts the nervous system and if too much of it enters the body it will inevitably cause death.
In the berries of the deadly Nightshade plant, atropine is found as an “L” isomer; however, the atropine used in medicine uses a racemic mixture of both “L” and “D” isomers. Amazingly, although atropine is very poisonous, like most harmful molecules we have found a way to exploit it for our own benefit!
With Dan Johnson’s story of Atropine, comes the story of an unfortunate lady who was nearly killed by her bitter Gin and Tonic. However, listening to this tail of attempted murder reminded me of a particularly intriguing assignation attempt I read about recently. The assassination of a man named “Markov” was carried out not with Atropine, but another molecule that is found within the deadly nightshade- Ricin. Ricin has caused a great scare in the media over the last century due to lots of failed assassination attempts using letters, however, the most intuitive way I think ricin was used was by umbrella. Markov was murdered after a tiny pellet of ricin was injected into his lower leg by an air gun disguised as an umbrella in a busy London street. Bizar, but deadly!
There is no known antidote for Ricin, and it is such a strong poison that only 7 micrograms is thought to be able to kill a person. Ricin is a molecule that consists of 2 chains. Chain B binds to a particular carbohydrate on the outside of the cell so allowing chain A to eventually enter into the cytoplasm and inhibit the production of enzymes which results in the death of the cell.
Ricin and Atropine are good examples of just two molecules from a deadly plant that have the capacity to cause serious damage, however in the case of both these molecules I find it encouraging to know that although they have the capacity to poison, they also (in some cases) have a capacity to cure, and so save life rather than extinguish it.
(To read more about deadly molecules read John Emsley’s “molecules of murder”).