A compound represented by the formula (I)
or the formula (II)
wherein R denotes a hydrogen atom or a lower alkyl group; Y and Z may be the same or different and independently denote alkylene groups containing 2-5 carbon atoms in their alkylene chains which may be substituted with a lower alkyl(s); X denotes a single bond or an alkylene group containing 1-10 carbon atoms in its alkylene chain which may be substituted with a lower alkyl(s); A-O- denotes a residue of a compound having an estrogenic activity and q denotes an integer of 1-3, and physiologically acceptable salts thereof.
The above compounds (I) or (II) are useful as a bone resorption inhibitor and a therapeutic agent for bone diseases.