As Gallus gallus (chicken species) is used as the model organism in some experiments, the three-dimensional structure of iNOS of G. gallus was generated. Further, the generated model was assess for structure assessment and geometrical errors and perform a molecular docking analysis against

a class of flavonoid (quercetin and its analogues) find more which is found in fruits, vegetables, leaves and grains and is reported to have effective anti-cancer property. 6 Additionally, there are reports of quercetin inhibiting against iNOS as anti-cancer agents. 7 But quercetin is limited by its low oral bioavailability for clinical use and therefore requires its molecular modification to enhance its pharmacological properties. 8 Here in the present work, the molecular docking analysis was studied for quercetin and its analogues against G. gallus iNOS enzyme. This was followed by ADME–Toxicity prediction (absorption, distribution, metabolism, and toxicity) of the docked compounds at the active site of the enzyme to evaluate its properties to be an orally active compound. The amino acid sequence of G. gallus nitric oxide synthase inducible RG7204 mw (Accession No: Q90703) was retrieved from the UniProtKB database (http://www.uniprot.org/). A BLAST 9 search was performed

and resulted with the best match Crystal Structure of inducible nitric oxide synthase (PDB ID: 4NOS (Chain A)) 10 with 81% similarity having a resolution of 2.25 Å making it an excellent template. The 3D structure was generated using Modeller 9v8 11 and the loop regions were refine using loop refinement script. The final model was validated using Swiss Model Assessment Server for PROCHECK (http://swissmodel.expasy.org/), Ramachandran plot, 12 ANOLEA 13 and Prosa (https://www.prosa.services.came.sbg.ac.at/prosa.php).

The root mean square deviation (RMSD) between the main chain atom (i.e. the backbone atoms of alpha carbon) of the template protein and the generated model was calculated by superimposing (4NOS) over the generated model to access the accuracy and reliability of the generated model using ICM Molsoft Browser (http://www.molsoft.com/). The generated 3D structure was deposited Calpain at the Protein Model Database (PMDB)14 and assigned the PMDB ID: PM0078016. The 2D structure of quercetin (CID5280343) was retrieved from the NCBI PubChem database and performed a chemical structure search at the NCBI PubChem database to retrieve the related compound and analogues. The search parameters were set at 95% similarity subjected to Lipinski rule of five filters15 resulting with 85 compounds. These compounds were then converted to their corresponding SYBYL mol2 (3D format) which and optimized using MM2 force field using ChemOffice 2010 (CambridgeSoft Corporation, MA 02139, USA). The generated 3D protein model was then imported in the Molegro Virtual Docker (Molegro Virtual Docker, DK-8000 Aarhus C, Denmark).