Patent ID: 8138165

Claim:
A compound according to formula I: wherein: R 1 and R 3 are each independently H, —SO 3 H, or —PO 3 H 2 ; R 2 is selected from, —SO 3 H or —PO 3 H; and X 1 is bound in the 2- or 3-position and is of the formula: Ar—X 3 wherein— Ar is phenyl and X 3 is selected from the group consisting of NR′R″, NHR′, hydroxyl. Alkoxy, carbooxyalkoxyalkoxy, hydroxyl(hydroxyalkyl)alkoxy and N,N-dialkylaminoalkoxy, wherein R′ and R′ are each independently selected from hydrogen, alkyl, N,N-(dialkylamino)alkyl, alkoxyalkyl, hydroxyalkyl, alkylsulfonyl and alkylsulfonato alkyl or pharmaceutically acceptable salts thereof.