The present invention provides a compound represented by formula (I):[Formula 1] ##STR00001## wherein n is an integer selected from 1 to 20, and R.sup.1 and R.sup.2, which may be the same or different, each represent a hydrogen atom, or a linear or branched C.sub.1-C.sub.6 alkyl group, or a salt, a prodrug or a solvate thereof, as well as a drug, a pharmaceutical composition containing the compound, and the like.