A QSAR model of Olanzapine derivatives as potential inhibitors for 5-HT2A Receptor

Schizophrenia is a complex, chronic mental disorder, affecting about 21 million people worldwide. It is characterized by symptoms, including distortions in thinking, perception, emotions, disorganized speech, sense of self and behavior. Recently, a numbers of marketed drugs for Schizophrenia are available against dopamine D2 and serotonin 5-HT2A receptors. Here, we docked Olanzapine derivatives (collected from literature) with 5-HT2A Receptor using the program AutoDock 4.2. The docked protein inhibitor complex structure was optimized using molecular dynamics simulation for 5ps with the CHARMM-22 force field using NAMD (NAnoscale Molecular Dynamics program) incorporated in visual molecular dynamics (VMD 1.9.2) and then evaluating the stability of complex structure by calculating RMSD values. NAMD is a parallel, object-oriented molecular dynamics code designed for high-performance simulation of large biomolecular systems. A quantitative structure activity relationship (QSAR) model was built using energy-based descriptors as independent variable and pKi value as dependent variable of eleven known Olanzapine derivatives with 5-HT2A Receptor, yielding correlation coefficient r2 of 0.63861. The predictive performance of QSAR model was assessed using different crossvalidation procedures. Our results suggest that a ligand-receptor binding interaction for 5-HT2A receptor using a QSAR model is promising approach to design more potent 5-HT2A receptor inhibitors prior to their synthesis.

Design, Synthesis and hMAO Inhibitory Screening of Novel 2-Pyrazoline Analogues

AIM AND OBJECTIVE

MAO inhibitors have a significant effect on the nervous system since they act in regulation of neurotransmitter concentrations. Neurotransmitter levels are critical for a healthy nervous system. MAO inhibitors can be used in the treatment of neurological disorders such as depression, Parkinson's disease and Alzheimer's disease, as the increase or decrease of some neurotransmitter concentrations is associated with these neurological disorders. This study was conducted to discover new and active MAO inhibitor drug candidates.

MATERIALS AND METHODS

New pyrazoline derivatives have been designed with the molecular docking approach and interactions of our compounds with the MAO enzyme have been investigated using the Autodock 4.2 program. The designed pyrazoline derivative compounds were synthesized by the reaction of the chalcones and hydrazides in ethanol. hMAO inhibitory activities of the newly synthesized compounds were investigated by fluorimetric method. In vitro cytotoxicity of five most potent inhibitors were tested in HepG2 cells.

RESULTS

(3-(5-bromo-2-hydroxyphenyl)-5-(4-methoxyphenyl)-4,5-dihydropyrazol-1-yl)(phenyl) methanone (5i) and (3-(2-hydroxy-4-methoxy phenyl)-5-p-tolyl-4,5-dihydropyrazol-1-yl)(phenyl) methanone (5l) inhibited hMAO-A more potently than moclobemide (Ki values are 0.004±0.001 and 0.005±0.001, respectively). The same two compounds, 5i and 5l, inhibited hMAO-A more selectively than moclobemide (SI values are 5.55x10-5 and 0.003, respectively). Both of these compounds were found non toxic at 1 µM, 5 µM and 25µM concentrations.

CONCLUSION

Two of the newly synthesized compounds, (3-(5-bromo-2-hydroxyphenyl)-5-(4- methoxyphenyl)-4,5-dihydropyrazol-1-yl)(phenyl)methanone and (3-(2-hydroxy-4-methoxy phenyl)- 5-p-tolyl-4,5-dihydropyrazol-1-yl)(phenyl) methanone were found to be promising MAO-A inhibitors due to their high inhibitory potency, high selectivity and low toxicity.