Disclosed are 3,4,5-trisubstituted aryl nitrone compoundsd and pharmaceutical compositions containing such compounds. The 3,4,5-trisubstituted aryl nitrone compounds have formula (I); where R¹-R⁴ are as defined in the specification. The disclosed compositions are useful as therapeutics for inflammation-related conditions in mammals, such as arthritis, and as analytical reagents for detecting free radicals.