Compounds which have utility in the treatment of conditions associated with altered mitochondrial function. The compounds have the following structure (I): ##STR1##

including stereoisomers, prodrugs, and pharmaceutically acceptable salts thereof, wherein R₁, R₂, R₃, R₄, R₅ and R₆ are as defined herein. Pharmaceutical compositions containing a compound of structure (I), as well as methods relating to the use thereof, are also disclosed.