Study on the biodistribution of deuterated biomolecules in mice aiming at new diagnostic radio-imaging agents

Deuterated compounds (2H-compounds) labeled with 14C prepared from deuterated algae, Chlorella ellipsoidea, were examined for their time-coursed distribution in mice after intravenous administration. The 14C-2H-compounds were fractionated and isolated from algae grown in practically 100 mol% 2H2O in the presence of 14C-bicarbonate. The fractions obtained were the "basic" and "acid" fractions, composed mainly of amino acids and sugar phosphates, respectively, and glucose, galactose, and lipid fractions. All fractions were examined for their biodistribution in mice bearing Ehrlich solid tumor in comparison with the fractions isolated from ordinary Chlorella (1H-Chlorella). 2H-Compounds thus examined showed some behaviors different from 1H-compounds. The 2H- "basic" fraction distributed more slowly in heart, lung and liver than the 1H-fraction. The 2H-specific large distribution in tumor was also observed on this fraction. The 2H-dependent characteristics in the distribution of glucose and galactose differed. The 2H-glucose level was lower in blood and higher in brain, resulting in a brain/blood ratio approximately twice that of 1H-glucose, while 2H-galactose did not show such a characteristic. These findings may be useful for the application of 2H-biomolecules to functional radio-imaging agents for nuclear medicine.