Compounds based on the following structures: wherein each of R1, R2, R3 and R4 is independently selected from: hydrogen, alkyl, and substituted alkyl； and each of R5, R6 and R7 is independently selected from: hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, N,N-dialkylamino, substituted N,N-dialkylamino, N-monoalkylamino, substituted N-monoalkylamino, and electron-donating substituents are useful in the treatment of disorders or conditions caused by or involving free radical-mediated or oxidative tissue damage.
