Molecular Docking, G-QSAR studies, Synthesis and Anticancer screening of some New 2-Phenazinamines as Bcr-Abl Tyrosine kinase Inhibitors.

The computational studies on 2-phenazinamines with their protein targets have been carried out to design compounds with potential anticancer activity. This strategy of designing compounds possessing selectivity over specific tyrosine kinase has been achieved through G-QSAR and molecular docking studies. The objective of this research has been to design newer 2-phenazinamine derivatives as Bcr-Abl tyrosine kinase inhibitors by G-QSAR, molecular docking studies followed by wet lab studies along with evaluation of their anticancer potential. Computational chemistry was done by using VLife MDS 4.3 and Autodock 4.2 followed by wet lab experiments for synthesizing 2-phenazinamine derivatives. The chemical structures of ligands in 2D were drawn by employing Chemdraw 2D Ultra 8.0 and were converted into 3D. These were optimised by using semi-empirical method called MOPAC. The protein structure was retrieved from RCSC protein data bank as PDB file. The binding interactions of protein and ligands was done by using PYMOL. The molecular properties of the designed compounds were predicted in silico by using Osiris property explorer. The parent compound 2-phenazinamine was synthesized by reduction of 2,4-dinitro-N-phenyl-benzenamine in the presence of tin chloride followed by cyclization in presence of nitrobenzene and magnesium sulfate. The derivatization at amino function of 2-phenazinamine was performed by treating parent compound with various aldehydes in the presence of dicyclohexylcarbodiimide (DCC) and urea to afford 2-(2-chlorophenyl)-3-(phenazin-2-yl) thiazolidin-4-one. Another series of derivatives was prepared by reacting parent compound with different aldehydes in the presence of p-toluylsulphonic acid, diphydropyridine and benzene sulfonyl chloride to afford benzenesulfonyl-N-(2-chlorobenzyl)-phenazin-2-amine. All the derivatives were tested for invitro anticancer activity on K562 human chronic myelogenous leukemia cell line by employing MTT assay method. The developed G-QSAR models were found to be statistically significant with respect to training (r2=0.8074), cross-validation (q2=0.6521), and external validation (pred_r2=0.5892). The best developed G-QSAR model suggested that the XlogP values of phenazinamine derivatives were highly influential in determining biological activity. Docking studies showed binding interactions of some derivatives with > 30% higher binding energy values than standard doxorubicin. The standard drug was found to exhibit binding energy - 6.79 kcal/mol and the derivatives 5b and 6c exhibited binding energy of - 7.46 and - 8.51; respectively. The lower energy values obtained for these derivatives indicate favourable interaction towards protein binding site as compared to standard doxorubicin. The findings obtained from G-QSAR and docking studies, were utilized for designing newer phenazinamine derivatives. The synthesis of these 2-phenazinamine derivatives (5a-m) is reported to be obtained from 2,4-dinitrodiphenylamine by applying appropriate synthetic route. These compounds 5a-m were further evaluated for anticancer activities. Compounds 5b, 6c were observed to possess good lipophilicity and were found to exhibit better activity than other compounds in the series, although less than standard doxorubicin. The studies of G-QSAR and molecular docking predicted better anticancer activity for the synthesized thiazolidones and benzenesulfonyl derivatives of phenazinamines as compared to standard doxorubicin. It is therefore surmised that the molecular manipulations at appropriate sites suggested by structure-activity relationship data will prove to be beneficial to give enhanced anticancer potential. Among the synthesized derivatives, compounds 5b and 6c showed better cytotoxic activity against K562 cancer cell line when compared to other compounds of the series, although less than standard doxorubicin.