Synthesis and biodistribution of six novel 99mTc complexes of 2-hydroxybenzaldehyde-amino acid Schiff bases

For the purpose of developing novel diagnostic pharmaceuticals of 99mTc-labeled small-size complexes, six novel complexes of 99mTc–2-hydroxybenzaldehyde-amino acid Schiff bases were designed and synthesized, and their biodistributions in mice were investigated. All the compounds were obtained in radiochemical yields higher than 90% at optimal conditions, and poor uptakes in muscle, brain, heart and tumor were commonly observed with rapid blood clearance. Potentiality was revealed of good kidney imaging by 2-hydroxybenzaldehyde-alanine (L2) complex within 40 min post-injection. Good bone uptake of 2-hydroxybenzaldehyde-histidine (L4) and 2-hydroxybenzaldehyde-aspartic acid (L5) complexes, high spleen accumulation of 2-hydroxybenzaldehyde-glycine (L1) and 2-hydroxybenzaldehyde-cysteine (L3) complexes, and non-specific biodistribution of 2-hydroxybenzaldehyde-glutamic acid (L6) complex were demonstrated.