Therapeutic agents

A compound of formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• X is O;
• R1 is selected from substituted aralkyl and substituted heteroaralkyl;
• R2 is substituted or unsubstituted alkylamine;
• R3 is 4-chlorophenyl;
• and
• R4-R7 represents groups R4, R5, R6 and R7 which are independently selected from hydrogen, halo, hydroxy, substituted or unsubstituted alkyl, substituted or unsubstituted hydroxyalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heteroaralkyl, substituted or unsubstituted alkylamine, substituted or unsubstituted alkoxy, trifluoromethyl, amino, nitro, carboxyl, carbonylmethylsulfone, trifluoromethylsulfone, cyano and substituted or unsubstituted sulfonamide.