Abstract: A compound of formula (I) (where X1 and X2 represent independently a hydrogen atom or a group of formula (II) R1 represents a linear or branched halogenoalkyl group having 1-7 carbon atoms; Ra represents a hydroxyl group and Rb represents a linear or branched alkynyl group having 2-5 carbon atoms, or Ra and Rb, when taken together with the carbon to which they are bound, represent a carbonyl group; m is an integer of 2-14; n is an integer of 2-7; provided that X1 and X2 are not both a hydrogen atom), stereoisomers of the compound, or hydrates, salts or esters thereof, as well as a pharmaceutical composition containing a therapeutically effective amount of the compound.