Patent ID: 8066970

Claim:
Compounds of formula (I) and salts or optical active isomers thereof, wherein each R 1 independently are the same or different and denote a moiety —CHOH—CHOH—CO—NR 3 —R; R 2 denotes hydrogen or a C 1 -C 4 alkyl where the alkyl group may be substituted by hydroxyl and amino groups and interrupted by an oxygen atom; each R 3 independently are the same or different and denote a hydrogen atom or an acyl group; each R independently are the same or different and denote a triiodinated phenyl group, preferably a 2,4,6-triiodinated phenyl group further substituted by two groups R 4 wherein each R 4 are the same or different and denote a hydrogen atom or a non-ionic hydrophilic moiety, provided that at least one R 4 group in the compound of formula (I) is a hydrophilic moiety.