Methods for improving mitochondrial function, decreasing iron accumulation, and/or decreasing oxidative stress by exposing cells or treating a subject to compounds or compositions of the general formula are described that are beneficial in treating, for example, diseases and conditions such as Friedreich's ataxia, normal aging, and various neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Furthermore, such compounds are useful as probes for identifying defects in mitochondrial metabolism, mitochondrial iron accumulation, cellular stress among other mitochondrial diseases and helping to identify compounds active in overcoming such defects.