Disaccharide ligands for selectins

A compound of formula (I), or a salt, solvate or hydrate thereof:

• ##STR55## wherein:
• X represents a divalent group selected from those of formulae I(a) to I(g) below ##STR56## wherein R.sub.1 and R.sub.2 independently represent hydrogen, C.sub.1-3 alkyl or --COOR.sub.6 where R.sub.6 is C.sub.1-6 alkyl;
• and R.sub.3 and R.sub.4 independently represent hydrogen, hydroxyl or C.sub.1-3 alkyl;
• and bonds a and b may be single or double;
• Y represents a single bond or a divalent group selected from those of formulae I(h) to I(j) below ##STR57## wherein R.sub.5 represents C.sub.1-3 alkyl or a glycosyl residue;
• each Z independently represents hydrogen or a hydroxyl protecting group;
• R.sup.1 represents hydrogen or a group --CH(OZ)CH.sub.2 (OZ) wherein Z has the meaning defined above;
• R.sup.2 represents hydrogen, a pharmaceutically acceptable cation, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, or (optionally substituted)phenyl-(C.sub.1-4) alkyl;
• R.sup.3 represents hydrogen, C.sub.1-6 alkyl, (C.sub.1-4) alkyl-substituted phenyl or benzoate;
• and
• n is 1, 2 or 3.