Patent ID: 7148352

Claim:
A compound of Formula 3 which is: or a pharmaceutically acceptable salt thereof, wherein: one of X 1 and X 2 is hydrogen and the other of X 1 and X 2 is selected from the group comprising of carbonyl; thiocarbonyl; ester; imino; amido; carboxylic acid; sulfonic acid; sulfinic acid; sulfamic acid; phosphonic acid; boronic acid; sulfate ester, hydroxyl; mercapto; cyano; cyanate; thiocyanate; isocyanate; isothiocyanate; carbonate; nitrate; nitro; alkylcarbonyl; alkylthiocarbonyl; alkoxycarbonyl; aminocarbonyl; halomethyl; dihalomethyl; trihalomethyl; and a halogen atom; and R 1 is selected from the group consisting of a monocyclic aryl substituted with at least one acid functional group, a polycyclic aryl substituted with at least one acid functional group, a heteroaryl substituted with at least one acid functional group, a monosaccharide substituted with at least one acid functional group and an oligosaccharide substituted with at least one acid functional group, wherein the at least one acid functional group substituted on R 1 is selected from the group consisting of —CO 2 H; —SO 3 H; —SO 2 H; —PO 3 H 2 ; —OSO 3 H; -alkyl-CO 2 H; -alkyl-SO 3 H; -alkyl-SO 2 H; -alkyl-PO 3 H 2 and -alkyl-OSO 3 H and wherein the alkyl group is a C 1 –C 4 alkyl group.