Thiol metabolism of the trypanosomatids as potential drug targets.

Trypanosomatids produce significant amounts of four major low molecular mass thiols, trypanothione, glutathionylspermidine, glutathione, and ovothiol A. Of these, only glutathione is present in cells of the host. All four low molecular mass thiols are directly or indirectly maintained in a reduced state by trypanothione reductase. Available evidence, from gene disruption studies, indicate that this is an essential enzyme. Attempts to exploit trypanothione reductase as a chemotherapeutic target lead to the design of competitive and irreversible inhibitors of the enzyme. A promising route involves the design of redox cyclers interacting specifically with trypanothione reductase as subversive substrates. Progress in studies on the biosynthesis of ovothiol A is summarized.