• Dr. Shikha Sahay

The synthesis of four novel ligands using the amino-acid cysteine and its ethyl carboxylate derivative is described. The synthetic method involves a two-step procedure, wherein the intermediate Schiff base formed by the condensation of the amino group of the cysteine substrate and salicylaldehyde is reduced to give the target ligands. The intermediates and the final products are characterised by high resolution NMR spectroscopy. Complexation studies of the ligands with 99mTc are standardised using stannous tartrate as the reducing agent at varying reaction conditions. The complexes are characterised using standard quality control techniques such as TLC, paper electrophoresis and PC. Lipophilicities of the complexes are estimated by solvent extraction into chloroform. Substantial changes in net charge and lipophilicity in the 99mTc complexes are observed on substituting the carboxylic acid residue in ligand I and II with the ethyl carboxylate groups (ligands III and IV). All the ligands formed complexes in high yield. While the complexes of ligand I and II are observed to be hydrophilic in nature and are not extractable into CHC13, ligands III and IV gave neutral and lipophilic complexes. Though the distribution ratios of the complexes of ligands III and IV in CHCI3/saline system are observed to be very high, considerable differences in lipophilicities are also observed as evidenced by the difference in their respective extractabilities in chloroform. On storage, the complex of ligand III exhibit a tendency to get converted to a hydrophilic and non-extractable species. The bio-distribution of the complexes of ligands I and II showed that they have predominantly renal clearances whereas the complexes of ligands III and IV exhibited a significant hepatobiliary uptake and did not show much uptake in brain in spite of its favourable properties such as neutrality, lipophilicity and conversion into a hydrophilic species.

“SYNTHESIS AND HARACTERIZATION OF LIGANDS AND BIFUNCTIONAL CHELATING AGENTS BY MODIFICATION OF CYSTEINE FOR COMPLEXATION STUDIES”

"“SYNTHESIS AND HARACTERIZATION OF LIGANDS AND BIFUNCTIONAL CHELATING AGENTS BY MODIFICATION OF CYSTEINE FOR COMPLEXATION STUDIES” ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.8, Issue 3, page no.293-298, March-2021, Available :http://www.jetir.org/papers/JETIR2103429.pdf

"“SYNTHESIS AND HARACTERIZATION OF LIGANDS AND BIFUNCTIONAL CHELATING AGENTS BY MODIFICATION OF CYSTEINE FOR COMPLEXATION STUDIES” ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.8, Issue 3, page no. pp293-298, March-2021, Available at : http://www.jetir.org/papers/JETIR2103429.pdf