The IUPAC name of menadione is 2-methylnaphthalene-1,4-dione. It is an intermediate in the chemical synthesis of vitamin K. This compound is very useful for investigating the processes in the living cells when electrochemical methods are used.
If you ask how it works, I can say that it goes through cells membrane, in cell it is reduced to menadiol and the goes back to the cells surface. Then it can be oxidized again to menadione and some kind of electrical signal may be received.
I said that is a vitamin, but it is toxic in large doses. If concentration of menadione in solution, when investigating living cells, is too big, the cells die.
P.S. There are no poisonous substances, only the doses are (distilled water is also poisonous, if you drink five liters of it)...
