Schiff base ligands are biologically active compounds in having antimicrobial, antiviral and antitumor activities etc. In this study, we have synthesized a Schiff base ligand namely 4-hydroxy-3-(2-hydroxy-3-methoxybenzylideneamino) benzoic acid, by reacting 3-amino-4-hydroxybenzoic acid and 2-hydroxy-3-methoxy benzaldehyde in the presence of acetic acid and refluxing it. The resulting base ligand was characterized on HPLC and used for radiolabelling with technetium-99m. The ligand 4-hydroxy-3-(2-hydroxy-3-methoxybenzylideneamino) benzoic acid was labelled with 99mTc at pH 7, while reacting 230 µg of ligand with 15 mCi of 99mTcO-4 for 10 min at room temperature. The resulting 99mTc-ligand complex was characterized by paper chromatography, TLC, HPLC and electrophoresis technique. The stability of the complex was determined at room temperature and in human serum. The biodistribution of the complex was studied in mice and scintigraphy was performed in rabbit. The 99mTc-ligand complex showed high radiolabelling yield (up to 99 ± 1%) and high stability at room temperature and in human serum. The newly prepared complex exhibited no net charge. Our newly developed 99mTc-ligand complex demonstrated high accumulation in liver and spleen of mice as well as in rabbit. Based on these findings, we have suggested that this novel radioligand i.e., 99mTc- 4-hydroxy-3-(2-hydroxy-3-methoxybenzylideneamino) benzoic acid complex could be used for liver and spleen imaging.
Keywords: 4-Hydroxy-3-(2-hydroxy-3-methoxybenzylideneamino) benzoic acid; Biodistribution; Electrophoresis; HPLC; Quality control; Radiolabelling; Scintigraphy.