Gliotoxin is a sulfur-containing mycotoxin that belongs to a class of naturally occurring 2,5-diketopiperazines produced by several species of fungi, especially those of marine origin. It is the most prominent member of the epipolythiopiperazines, a large class of natural products featuring a diketopiperazine with di- or polysulfide linkage. These highly bioactive compounds have been the subject of numerous studies aimed at new therapeutics. Gliotoxin was originally isolated from Gliocladium fimbriatum, and was named accordingly. It is an epipolythiodioxopiperazine metabolite that is one of the most abundantly produced metabolites in human invasive Aspergillosis (IA).