nightshade makes a number of chemicals called alkaloids, one of which: atropine is particulalry dangerous becuase it affects nerve cells. The effect it has is very similar to some nerve gasses used in the second world war and can cause the nervous system to break down stopping you from breathing. Nasty stuff. But like a lot of chemicals, the poison is in the dose. Atropine is also used as a drug to treat a number of diseases.