Compounds of formula (I) wherein: Q represents an amidino group, a cyano group or a group of formula XYN—, (where X and Y are hydrogen or various groups); Ra represents alkylene; Rb and Rc each represents alkylene, the total number of carbon atoms in said straight chains of Rb and Rc being 7); R2 and R3 each represents hydrogen, or a group of formula R, RCO—, ROCO—, or RNHCO—, where R represents alkyl or aryl; the chiral carbon atom indicated by the asterisk is in the L configuration; Z is an aromatic amino acid residue; n is 0 or 1; R1 represents hydrogen, alkyl or aryl; and W represents hydrogen, alkyl or aryl; and pharmaceutically acceptable salts thereof have the ability to protect against the neuronal damage which may be caused by an ischemic event.