Compounds that may be used for the treatment or prevention of a condition associated with T-cell proliferation or that is mediated by pro-inflammatory cytokines are of formula (I): wherein at least one of R1, R2 or R3 is not H and each is independently H, alkyl, CF.sub.3, CONH.sub.2, CN, halogen, NH.sub.2, NO.sub.2, NHCHO, NHCONH.sub.2, NHSO.sub.2alkyl, SOMe, SO.sub.2NH.sub.2, Salkyl, or CH.sub.2S0.sub.2alkyl; and R.sub.4 is H or alkyl; or a salt thereof. ##STR00001##