The present invention is directed to compounds represented by the following structural formula, and pharmaceutically acceptable salts, solvates and hydrates thereof, R1 is a substituted or unsubstituted group selected from C.sub.1-C.sub.8 alkyl, aryl-C.sub.0-2-alkyl, heteroaryl-C.sub.0-2-alkyl, C.sub.3-C.sub.6 cycloalkylaryl-C.sub.0-2-alkyl or phenyl. W is O or S. R2 is H or a substituted or unsubstituted group selected from C.sub.1-C.sub.6 alkyl, C.sub.3-C.sub.6 cycloalkyl and heteroaryl. X is a C.sub.2-C.sub.5 alkylene linker wherein one carbon atom of the linker may be replaced with O, NH or S. Y is C, O, S, NH or a single bond. Furthermore, E is (CH.sub.2).sub.nCOOH, wherein n is 0, 1, 2 or 3, or C(R3)(R4)A, wherein A is an acidic functional group such as carboxyl, carboxamide substituted or unsubstituted sulfonamide, or substituted or unsubstituted tetrazole. R3 is H, saturated or unsaturated C.sub.1-C.sub.5 alkyl, C.sub.1-C.sub.5 alkoxy. Additionally, R4 is H, halo, a substituted or unsubstituted group selected from C.sub.1-C.sub.5 alkyl, C.sub.1-C.sub.5 alkoxy, C.sub.3-C.sub.6 cycloalkyl, arylC.sub.0-C.sub.4alkyl and phenyl, or R3 and R4 are combined to form a C.sub.3-C.sub.4 cycloalkyl.