Correlation of lipophilicity to biodistribution of 99mTc-labelled aminothiols

Synthesis and Characterization of Oxotechnetium(V) Mixed-Ligand Complexes Containing a Tridentate N-Substituted Bis(2-mercaptoethyl)amine and a Monodentate Thiol

“…Technetium-99m is the radioisotope of choice for imaging, due to its ideal γ-photon energy of 140KeV, lack of particular radiation dose, half life of 6 h, and convenient availability. Recently, emphasis has been given to the design and preparation of neutral, lipophilic technetium complexes for brain imaging …”

Looking for New [1,2,4,5]Tetrazines to Produce 99mTc‐Labelled Derivatives, with a Suitable Lipophilicity Balance for Use in Bioorthogonal Reactions

“… As it is expected, for drug uptake by passive diffusion described for different drugs' organs intakes, [30–33] there is a parabolic tendency between lipophilicity and accumulation in the liver. The high hydrophilicity of the new radiolabelled derivatives, 99m Tc‐(5) and 99m Tc‐(8) , leads to an intermediate accumulation in the liver (compared to the parent compounds 99m Tc‐(1) , 99m Tc‐(2) and 99m Tc‐(3) ).…”

“…To analyze the relationship between logD 7.4 and biodistribution, logD 7.4 vs % ID/g (1 h post-injection) , [20,21] were graphed for the studied compounds (included in Table 2) and three of the most relevant organs, i. e. liver, intestines and kidneys (Figure 5). The results allowed us to analyse whether the hypothesis related to the hydrophilicity of the chelating agent and biodistribution was valid: i) As it is expected, for drug by passive diffusion described for different drugs' organs intakes, [30][31][32][33] there is a parabolic tendency between lipophilicity and accumulation in the liver. The high hydrophilicity of the new radiolabelled derivatives, 99m Tc-( 5 Tc-counterparts described herein, we were not able to obtained the optimal lipophilicity (the minimum in the curve) to minimize the bioaccumulation in the liver.…”