Why are zinc and aluminium coumpounds the active ingredients in anti-perspirants and deodarants?

Answer 1

It is because they are relatively non-toxic when compared to other metallic compounds and they are usually present a arsenals so they wont settle on your body but evaporate into air instead.

But the main reason why they are used is due to their anti-bacterial properties.

Answer 2

I'm not positive, but I know that metals have antibacterial properties. I'm guessing that these compounds prevent growth of the bacteria that cause the smell.