Design, synthesis and anti-HIV activity of novel quinoxaline derivatives.

In order to design novel anti-HIV agents, pharmacophore modelling, virtual screening, 3D-QSAR and molecular docking studies were performed. Pharmacophore model was generated using 17 structurally diverse molecules using DISCOtech followed by refinement with GASP module of Sybyl X. The best model containing four features; two donor sites, one acceptor atom and one hydrophobic region; was used as a query for virtual screening in NCI database and 6 compounds with Qfit value ≥98 were retrieved. The quinoxaline ring which is the bio-isostere of pteridine ring, retrieved as a hit in virtual screening, was selected as a core moiety. 3D-QSAR was carried on thirty five 5-hydroxy-6-oxo-1,6-dihydropyrimidine-4-carboxamide derivatives. Contour map analysis of best CoMFA and CoMSIA model suggested incorporation of hydrophobic, bulky and electronegative groups to increase potency of the designed compounds. 50 quinoxaline derivatives with different substitutions were designed on basis of both ligand based drug design approaches and were mapped on the best pharmacophore model. From this, best 32 quinoxaline derivatives were docked onto the active site of integrase enzyme and in-silico ADMET properties were also predicted. From this data, synthesis of top 7 quinoxaline derivatives was carried out and were characterized using Mass, (1)H-NMR and (13)C-NMR spectroscopy. Purity of compounds were checked using HPLC. These derivatives were evaluated for anti-HIV activity on III-B strain of HIV-1 and cytotoxicity studies were performed on VERO cell line. Two quinoxaline derivatives (7d and 7e) showed good results, which can be further explored to develop novel anti-HIV agents.