Salvarsan is an arsenic-containing drug that was first used for the treatment of:

1. Syphilis

2. Typhoid

3. Meningitis

4. Dysentery

 
HINT: Salvarsan is used for the treatment of Syphilis.
Explanation: Syphilis is an acute and chronic infectious disease caused by the bacterium Treponema pallidum.

It is a sexually transmitted infection. The primary route of transmission is through sexual contact but it may also be transmitted from mother to fetus during pregnancy or at birth.

Paul Ehrlich investigated arsenic-based structures in order to produce fewer toxic substances for the treatment of syphilis as he got a Nobel prize for medicine in 1908 for this discovery.

Salvarsan was the first effective medicine discovered for syphilis. Although salvarsan is toxic to human beings, its effect on bacteria is much greater than on human beings.

The structure of salvarsan is-