Complex sentence: Microbicides for sexually transmitted diseases are pharmacologic agents and chemical substances that are capable of killing or destroying certain microorganisms that commonly cause human infection, for example the human immunodeficiency virus.
Split into simpler sentences: Microbicides for sexually transmitted diseases are pharmacologic agents and chemical substances capable of killing or destroying certain microorganisms. Microbicides are designed to target microorganisms that commonly cause human infection, for example the human immunodeficiency virus.