Search for Structural Requirements of 2-Phenylimidazo(1,2-. ) pyridineacetamide Analogs to Improve Affinity and Selectivity towards Central and/or Peripheral Benzodiazepine Receptors
BioChem Press, Soma Samanta, Parthasarathi Panda, Tarun Jha · 2007
Motivation. Central benzodiazepine receptors (CBRs) and peripheral benzodiazepine receptors (PBRs) are benzodiazepine receptors present in the brain. These receptors play valuable roles in calcium flow, cell proliferation, cellular immunity, cellular respiration, malignancy, muscle relaxation and sedation. 2– Phenylimidazo[1,2–�. ]pyridineacetamide analogs are potent and selective ligands for CBRs and PBRs. An attempt is made to find out the required structural features responsible for high affinity and selectivity of 2– phenylimidazo[1,2–�. ]pyridineacetamide analogs towards CBRs or PBRs through computational design. Method. A QSAR study of 37 analogs of 2–phenylimidazo[1,2–�. ]pyridineacetamide was performed using topological and quantum chemical descriptors. Correlation and multiple regression analyses were performed to develop QSAR models. Results. The present study showed that some atoms played important roles in electronic and hydrophobic interactions with central benzodiazepine receptors (CBRs) for improving affinity and selectivity of these compounds. Atomic charges of some atoms, dipole moment, total energy as well as the presence of acetamide group and double substitution on carboxamide nitrogen favor the high affinities and selectivities of PBRs. Conclusions. The QSAR models developed in this study are used to generate a possible mapping of the pharmacophore. The QSAR equations explain the importance of particular atoms/groups for CBRs or PBRs affinity. The presence of a chlorine atom at ‘Y’ is favorable to the CBRs affinity whereas the presence of an acetamide group and disubstitution on carboxamide nitrogen favor PBRs affinity.