The relationship between structure and biodistribution of 99Tcm-pyridoxylamino acids for hepatobiliary imaging agents

In order to investigate the relationship between structure and biodistribution of 99Tcm-pyridoxylamino acids (PA), pyridoxylamino-L-tryptophan (PHT), pyridoxylamino-L-cystine (PHC) and pyridoxylamino-tyrosine (PHY) are labelled with 99Tcm using Sn(II) as a reductant. The labelling yields of 99Tcm-PA is better than 95% at pH = 7.0. The partition coefficients as lipophilic parameter in the octanol-water system are determined. The biodistribution in male mice shows that 99Tcm-PA have fast blood clearance, but the difference is apparent in their hepatobiliary uptakes and intestinal accumulations. Particularly, there is a good correlation between the hepatobiliary uptake and the partition coefficient. The partition coefficient larger is, the lipophilicity larger is. This result may be valuable for developing new 99Tcm-PA of hepatobiliary imaging agent