One embodiment of the present invention is a compound represented by the Structural Formula (I): Y is a covalent bond of a substituted or unsubstituted straight chained hydrocarbyl group. In addition, Y, taken together with both >C═Z groups to which it is bonded, is a substituted or unsubstituted aromatic group. Preferably, Y is a covalent bond or —C(R7R8)—.R1 is an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic group, or a substituted non-aromatic heterocyclic group, R2-R4 are independently —H, an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic group, a substituted non-aromatic heterocyclic group, an aryl group or a substituted aryl group, or R1 and R3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R2 and R4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring.R5-R6 are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group.R7 and R8 are each independently —H, an aliphatic or substituted aliphatic group, or R7 is —H and R8 is a substituted or unsubstituted aryl group, or, R7 and R8, taken together, are a C2-C6 substituted or unsubstituted alkylene group.Z is ═O or ═S.Also disclosed are pharmaceutical compositions comprising the compound of the present invention and a pharmaceutically acceptable carrier or diluent.