This invention provides fused heterocycles having the formula: in which R1 is a member selected from the group consisting of H, substituted or unsubstituted arylalkyl and substituted or unsubstituted heteroarylalkyl. R2 is a member selected from the group consisting of H substituted or unsubstituted alkenyl, substituted or unsubstituted arylalkyl and substituted or unsubstituted heteroarylalkyl. R3is a member selected from the group consisting of H, C1-C6 substituted or unsubstituted alkyl, substituted or unsubstituted arylalkyl and substituted or unsubstituted heteroarylalkyl. R4 is a member selected from OH and O−X+, in which X+ is positive ion which is a member selected from organic positive ions and inorganic positive ions. Substituted or unsubstituted arylalkyl and substituted or unsubstituted heteroarylalkyl moieties have the formula: in which Ar is a member selected from the group consisting of substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. The index n is an integer from 1 to 4.