Studies in molecular modeling, in-vitro CDK2 inhibition and antimetastatic activity of some synthetic flavones.

Naturally occurring flavonoids have been shown to possess anticancer activity. We have previously shown that certain synthetic flavonoids also exert significant antiproliferative potential in MOLT-4, MCF-7, and HepG2 cell lines. To this end, we evaluated eight synthetic flavones for their CDK2 binding by molecular docking. Most flavones showed interaction with Leu 83. Based on docking and antiproliferative activity, we chose 3'-nitroflavone and 3', 5'-dimethoxyflavone for the molecular dynamics (MD) simulation and CDK2 inhibition studies. MD simulation studies confirmed interactions with CDK2 (as observed in docking). Furthermore, the inhibitory activities of CDK2/cyclin A2 enzyme for 3'-nitroflavone and 3', 5'-dimethoxyflavone were found to be 6.17 and 7.19 �M, respectively. 3'-nitroflavone and 3', 5'-dimethoxyflavone displayed moderate activity in colony formation assay, wound-scratch assay, and Leighton tube studies. Based on these data, the synthesized flavones might have clinical potential as potential inhibitors of CDK2.

Pharmacophore and Docking Guided Virtual Screening Study for Discovery of Type I Inhibitors of VEGFR-2 Kinase.

BACKGROUND: Kinase domain of VEGFR-2 displays conformational flexibility which leads to existence of two kinds of inhibitors viz. type I and type II inhibitors. They exhibit different binding modes and this necessitates the development of separate pharmacophore models for them. METHODS: The virtual screening study for discovery of type I inhibitors of VEGFR-2 kinase was done by using combined pharmacophore (generated using PHASE and validated by 3D-QSAR) and docking (Glide) based approach. Validated pharmacophore was used as preliminary filter followed by docking. ADME properties were predicted for retrieved hits using QikProp. RESULTS: ADHRR.94 with statistical parameters r2 test 0.94, r2 training 0.99, SD 0.0766, r2 0.9861, F 283.3, RMSE 0.2605, q2 0.8115 and Pearson's R 0.9723was identified as the best pharmacophore hypothesis for type I inhibitors of VEGFR-2 kinase. Virtual screening study was done for Asinex Elite Libraries comprising of 104400 molecules using ADHRR.94, HTVS docking and XP docking that resulted in twelve hits. Asinex ligand 5686 with docking score of -10.48kcal/mol was top-ranking hit. It made two hydrogen bonding interactions with Cys 919, one as an acceptor and other as a donor, which are characteristic of type I inhibitors. Additional interactions observed were π-cation with Lys 868 and π- πstacking with Phe 1047.Twelve hits had acceptable values for ADME properties. CONCLUSION: Twelve hits with best obtained docking scores ranging from -10.48 to -7.23 kcal/mol and mimicking characteristic type I inhibitor interactions were identified which could be probable inhibitors of VEGFR-2.

Localization and interaction of hydroxyflavones with lipid bilayer model membranes: a study using DSC and multinuclear NMR.

The localization and interaction of six naturally occurring flavones (FLV, 5HF, 6HF, 7HF, CHY and BLN) in DPPC bilayers were studied using DSC and multi-nuclear NMR. DSC results indicate that FLV and 6HF interact with alkyl chains. The (1)H NMR shows interaction of flavones with the sn-glycero region. Ring current induced chemical shifts indicate that 6HF and BLN acquire parallel orientation in bilayers. 2D NOESY spectra indicate partitioning of the B-ring into the alkyl chain region. The DSC, NMR and binding studies indicate that 5HF and 7HF are located near head group region, while 6HF, CHY and BLN are located in the vicinity of sn-glycero region, and FLV is inserted deepest in the membrane.

In-vitro anti-proliferative and anti-oxidant activity of galangin, fisetin and quercetin: role of localization and intermolecular interaction in model membrane.

Flavonols are an important class of naturally occurring molecules and are known for their pharmacological activity. The activity is associated with the ability of flavonols to influence membrane-dependent processes. We have investigated the in-vitro anti-proliferative and anti-oxidant activity of galangin (GLN), fisetin (FTN) and quercetin (QTN), which possess variable number of phenolic hydroxyl groups. An attempt has been made to correlate the biological activity of these molecules with their interaction and localization in dipalmitoyl phosphatidyl choline (DPPC) bilayers, using differential dcanning calorimetry (DSC) and nuclear magnetic resonance (NMR) methods. Results indicate that GLN interacts to the alkyl chains of the lipid bilayer involving hydrophobic interactions. FTN and QTN interact with head region and sn-1-glycero region involving hydrogen bonding. Ring current induced chemical shifts of lipid protons, due to intermolecular interaction indicate that GLN acquires a parallel orientation with respect to the bilayer normal whereas FTN and QTN resume a mixed orientation. The membrane binding constants of these molecules are in the order GLN > QTN > FTN. It has been shown that the number and position of hydroxyl groups in these molecules play an important role in membrane binding and thereby in biological activity.

A simple HPLC method for quantitation of quercetin in herbal extracts.

A reversed-phase HPLC method with UV detection was developed for the determination of quercetin. The method produced linear response over a wide concentration range, with an average accuracy of 95% and average intra- and interday variation of 0.75 and 0.3, respectively. The exactness of the method was proven by determining the recovery rates from 50 to 150% of standard concentration, which were found within the acceptable range of 95 to 105%. The method was used for quantitation of quercetin in the extracts of Psidium guajava, Vitis vinifera, and extracts rich in quercetin and other flavonols in the flavonoid family.