IDENTIFICATION OF POTENTIAL NOVEL EGFR INHIBITORS USING A COMBINATION OF PHARMACOPHORE AND DOCKING METHODS

Objective: Identifying new inhibitors of Epidermal Growth Factor Receptor (EGFR) by virtual screening using a pharmacophore model followed by docking. Methods: A pharmacophore model was developed using a dataset of 77 chemically diverse EGFR inhibitors using PHASE. Statistically valid Three Dimensional Quantitative Structure Activity Relationship (3D-QSAR) equations were generated for the pharmacophore model. This was followed by database screening to obtain probable hits. Docking of the probable hits into the crystal structure of EGFR was used as a second filter. Docking studies were carried out using GLIDE. Calculation of ADME properties of the probable hits arising out of docking further reduced the number of hits. Results: A five-point pharmacophore was generated for EGFR inhibitors reported in literature. The pharmacophore indicated that the presence of two aromatic ring features (R), one acceptor feature (A), one donor feature (D) and one hydrophobic feature (H) is necessary for potent inhibitory activity. The generated pharmacophore yielded statistically significant 3D-QSAR model, with a correlation coefficient r2 of 0.9905 and q2 of 0.8764. Virtual screening using the best pharmacophore model resulted in 372 hits. Docking studies as a second filter reduced the hits to 8. Application of drug-likeness as a third filter gave 6 leads.Conclusion: 6 leads with satisfactory pharmacokinetics properties were identified as potential EGFR inhibitors. This study may facilitate development of some new potential EGFR inhibitors. Â

LOCALIZATION AND ORIENTATION OF METHOXY FLAVONOIDS IN DPPC BILAYERS: EFFECT ON THEIR ANTI-PROLIFERATIVE ACTIVITY

Objective: Flavones and flavonols are an important class of naturally occurring flavonoids. They are well known for their pharmacological activity. This activity is associated with the ability of flavones and flavonols to influence membrane–dependent processes. In this paper, we have reported localization, orientation and interaction, of four synthesized flavone/flavonols with 1, 2–dipalmitoyl–sn–glycero–3–phosphocholine (DPPC) bilayers. These are compared with standard flavone; chrysin (CHY) and flavonol Quercetin (QUE).Methods: The molecules studied are 4ʹ–methoxy flavone (MF), 3ʹ,4ʹ–dimethoxyflavone (DMF), 4ʹ–methoxyflavonol (MF–ol) and 3ʹ,4ʹ–dimethoxyflavonol (DMF–ol). The techniques used are Differential Scanning Calorimetry (DSC) and multi–nuclear NMR.Results: Highest binding to lipid bilayers is shown by DMF, followed by QUE. Based on DSC studies it is seen, that maximum interaction of MF and DMF, takes place with the hydrophobic core of lipid bilayers. DMF–ol shows formation of a heterogeneous system at higher concentrations. The 1H NMR spectra of unilamellar vesicles of DPPC, incorporated with MF, DMF and MF–ol shows significant interaction of these compounds with the alkyl chain of the hydrophobic core. MF, DMF and MF–ol acquire parallel orientation in bilayers with the B–ring pointing towards hydrophobic core, while DMF–ol acquire mixed orientation. This may be ascribed to the presence of two methoxy and one hydroxyl group on the B–ring of DMF–ol which hinders its partitioning inside the hydrophobic core of lipid bilayer. Multi–lamellar vesicles (MLV) of DPPC incorporated with flavones, show maximum increase in Chemical Shift Anisotropy in 31P spectrum of DMF. This is followed by MF. DSC.Conclusion: NMR and binding studies indicate that DMF is partitioned deeply inside the hydrophobic core, while MF, MF–ol and DMF–ol are mostly located in the vicinity of sn–glycero region. Therefore, we conclude that DMF which penetrates deepest inside the hydrophobic core also shows the highest anti–proliferative activity against K562 and MCF–7 cancer cell lines. Its activity is also better than CHY