Patent ID: 8071811

Claim:
Compounds of formula (I) wherein each R 1 denote the moiety â€”Aâ€”NBâ€”R; R 2 denotes a hydrogen atom, a hydroxyl group, a C 1 to C 4 alkyl group or a C 1 to C 4 alkoxy group; each A are the same or different and are a C 1 to C 4 alkylene group optionally substituted by 1 to 3 hydroxyl groups; each B are the same or different and denotes a hydrogen atom and an acyl group; each R are the same or different and denote a triiodinated phenyl group, further substituted by two groups R 3 wherein each R 3 are the same or different and denote hydrogen or a non-ionic hydrophilic moiety, provided that at least one R 3 group in the compound of formula one is a hydrophilic moiety; and salts and optical isomers thereof.