The invention relates to compounds according to Formula (I):

##STR00001## wherein A isAs(OH).sub.2 or an arsenoxide equivalent group; each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is independently selected from H, X, OH, NH.sub.2, CO, SCN, CH.sub.2NH, NHCOCH.sub.3, NHCOCH.sub.2X or NO, and X is a halogen; R.sub.5 is NHCH.sub.2COOH, OH or OR.sub.6, wherein R.sub.6 is a C.sub.1-.sub.5 straight or branched alkyl group; and Z is a radioisotope with a half-life of less than 4 days, or a pharmaceutically acceptable salt, ester, prodrug or solvate thereof, uses of said compounds, and methods of preparing said compounds. The invention also relates to diagnostic methods utilizing said compounds.

The invention relates to compounds according to Formula (I):

##STR00001## wherein A isAs(OH).sub.2 or an arsenoxide equivalent group; each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is independently selected from H, X, OH, NH.sub.2, CO, SCN, CH.sub.2NH, NHCOCH.sub.3, NHCOCH.sub.2X or NO, and X is a halogen; R.sub.5 is NHCH.sub.2COOH, OH or OR.sub.6, wherein R.sub.6 is a C.sub.1-.sub.5 straight or branched alkyl group; and Z is a radioisotope with a half-life of less than 4 days, or a pharmaceutically acceptable salt, ester, prodrug or solvate thereof, uses of said compounds, and methods of preparing said compounds. The invention also relates to diagnostic methods utilizing said compounds.