Project description:The asymmetric unit of the title compound, C(12)H(12)N(2), contains two half-mol-ecules related by an inversion center, the planes of their pyridine rings being oriented at a dihedral angle of 69.62 (4)°. In the crystal structure, a π-π contact between the pyridine rings [centroid-centroid distance = 3.895 (3) Å] may stabilize the structure. A weak C-H⋯π inter-action is also found.
Project description:Cyclic nitrones have been employed for decades as spin trapping reagents for the detection and identification of transient radicals, and have been employed as pharmacological agent against ROS-mediated toxicity. The short half-life of the nitrone-superoxide adducts limits the application of nitrones in biological millieu, and therefore investigaton of the redox properties of the superoxide adducts is important. Moreover, computational investigation of the redox properties of the nitrones and their corresponding spin adducts may provide new insights into the nature of their pharmacological activity against ROS-induced toxicity. In general, electron-withdrawing group substitution at the C-5 position results in higher EAs and IPs making these substituted nitrones more susceptible to reduction but more difficult to oxidize compared to DMPO. One-electron reduction and oxidation of nitrones both resulted in elongated N-C(2) bonds indicating the tendency of radical anion and cation forms of nitrone to undergo ring-opening. The EAs and IPs of various O(2)(*-) adducts indicate that DEPMPO-O(2)H is the most difficult to reduce and oxidize compared to the O(2)(*-) adducts of DMPO, EMPO, and AMPO. In general, nitroxides gave higher EAs compared to nitrones making them more suceptible to reduction. One-electron oxidation of nitroxides leads to elongation of the N-C(2) bond but not for their reduction. The energetics of redox reaction of O(2)(*-) adducts was also explored. Results indicate that the reduction of O(2)(*-) adducts with O(2)(*-) is preferred followed by their oxidation by O(2) and then by O(2)(*-), but the maximum difference between these free energies of redox reactions in aqueous solution is only 0.21 kcal/mol. The preferred decomposition pathways for the one-electron oxidation and reduction of nitroxides was also explored, and formation of potentially biologically active products such as NO, H(2)O(2), and hydroxamic acid was predicted.
Project description:Insecticide resistance has limited the number of available chemical options for insect pest control. Hence there is a need for new chemistries with novel modes of action. Here we investigate the mode of action for an insecticide that has not yet been released for commercial use. The ovicidal, larvacidal and adulticidal effects of 5,5'-dimethyl -2, 2'-dipyridyl (termed Ha44), which is being developed as a treatment for head lice, were evaluated in the Drosophila melanogaster model system. Ha44 demonstrated significant activity against embryos and was capable of arresting development at a number of stages of embryogenesis. The effects of Ha44 on embryos was shown to be reversible following the addition of the metal ions Fe(II) and Fe(III), Cu and Zn. When larvae were exposed to Ha44, lethality was recorded at similar concentrations to those observed for embryos. Using an eYFP reporter system it was shown that Ha44 was able to reduce the levels of both copper and zinc in the digestive tract, confirming the binding of Ha44 to these metals in vivo. Ha44 has further been shown to inhibit a zinc containing metalloproteinase in vitro. Exposure of adult flies to Ha44 resulted in lethality, but at higher concentrations than those observed for embryos and larvae. The median lethal dose in adult flies was shown to be associated with the type of exposure, with an LD-50 of 1.57 mM being recorded following the direct contact of flies with Ha44, while an LD-50 of 12.29 mM was recorded following the ingestion of the compound. The capacity of Ha44 to act on all stages of the life-cycle and potentially via a range of targets suggests that target site resistance is unlikely to evolve.
Project description:Allosteric modulators are ligands for proteins that exert their effects via a different binding site than the natural (orthosteric) ligand site and hence form a conceptually distinct class of ligands for a target of interest. Here, the physicochemical and structural features of a large set of allosteric and non-allosteric ligands from the ChEMBL database of bioactive molecules are analyzed. In general allosteric modulators are relatively smaller, more lipophilic and more rigid compounds, though large differences exist between different targets and target classes. Furthermore, there are differences in the distribution of targets that bind these allosteric modulators. Allosteric modulators are over-represented in membrane receptors, ligand-gated ion channels and nuclear receptor targets, but are underrepresented in enzymes (primarily proteases and kinases). Moreover, allosteric modulators tend to bind to their targets with a slightly lower potency (5.96 log units versus 6.66 log units, p<0.01). However, this lower absolute affinity is compensated by their lower molecular weight and more lipophilic nature, leading to similar binding efficiency and surface efficiency indices. Subsequently a series of classifier models are trained, initially target class independent models followed by finer-grained target (architecture/functional class) based models using the target hierarchy of the ChEMBL database. Applications of these insights include the selection of likely allosteric modulators from existing compound collections, the design of novel chemical libraries biased towards allosteric regulators and the selection of targets potentially likely to yield allosteric modulators on screening. All data sets used in the paper are available for download.
Project description:In the title compound, [Pt(CH(3))(3)I(C(12)H(12)N(2))], the Pt(IV) atom is six-coordinated in a slightly distorted octa-hedral configuration with one CH(3) group and the I atom forming a near perpendicular axis relative to the square plane formed by the bipyridine ligand and the two remaining CH(3) groups. The CH(3) group trans to the I atom has a slightly elongated bond to Pt compared to the other CH(3) groups, indicating a difference in trans influence between iodine and the bipyridine ligand.
Project description:In the title compound, C(17)H(16)O(6), the two methyl salicylate moieties are related by crystallographic twofold rotational symmetry with the two benzene rings close to being perpendicular [inter-ring dihedral angle = 86.6 (8)°]. Intra-molecular phenolic O-H⋯O hydrogen bonds with carboxyl O-atom acceptors are present, with these groups also involved in centrosymmetric cyclic inter-molecular O-H⋯O hydrogen-bonding associations [graph set R(2) (2)(4)], giving infinite chains extending across (101).
Project description:In the mol-ecule of the title compound, [HgI(2)(C(12)H(12)N(2))], the Hg(II) atom is four-coordinated in a distorted tetra-hedral configuration by two N atoms from 5,5'-dimethyl-2,2'-bipyridine and two I atoms. There is a π-π contact between pyridine rings of adjacent molecules [centroid-centroid distance = 3.723 (5) Å].
Project description:The basement membrane is a specialized extracellular matrix substrate responsible for support and maintenance of epithelial and endothelial structures. Engineered basement membrane-like hydrogel systems have the potential to advance understanding of cell-cell and cell-matrix interactions by allowing precise tuning of the substrate or matrix biochemical and biophysical properties. In this investigation, we developed tunable hydrogel substrates with conjugated bioactive peptides to modulate cell binding and growth factor signaling by endothelial cells. Hydrogels were formed by employing a poly(ethylene glycol) crosslinker to covalently crosslink gelatin polymers and simultaneously conjugate laminin-derived YIGSR peptides or vascular endothelial growth factor (VEGF)-mimetic QK peptides to the gelatin. Rheological characterization revealed rapid formation of hydrogels with similar stiffnesses across tested formulations, and swelling analysis demonstrated dependency on peptide and crosslinker concentrations in hydrogels. Levels of phosphorylated VEGF Receptor 2 in cells cultured on hydrogel substrates revealed that while human umbilical vein endothelial cells (HUVECs) responded to both soluble and conjugated forms of the QK peptide, conditionally-immortalized human glomerular endothelial cells (GEnCs) only responded to the conjugated presentation of the peptide. Furthermore, whereas HUVECs exhibited greatest upregulation in gene expression when cultured on YIGSR- and QK-conjugated hydrogel substrates after 5 days, GEnCs exhibited greatest upregulation when cultured on Matrigel control substrates at the same time point. These results indicate that conjugation of bioactive peptides to these hydrogel substrates significantly influenced endothelial cell behavior in cultures but with differential responses between HUVECs and GEnCs.
Project description:In the mol-ecule of the title compound, C(16)H(20)N(4), the 1,3-diazinane ring adopts a chair conformation and the dihedral angle formed by the pyridine rings is 78.64?(8)°. The mol-ecular conformation is stabilized by an intra-molecular C-H?N hydrogen bond, forming an S(6) ring motif. In the crystal, centrosymmetrically related mol-ecules are linked into dimers by pairs of N-H?N hydrogen bonds, generating rings of R(2) (2)(10) graph-set motif.
Project description:The asymmetric unit of the title compound, [ZnCl(2)(C(12)H(12)N(2))], contains two independent mol-ecules. The Zn(II) atoms are four-coordinated in distorted tetra-hedral configurations by two N atoms from 5,5'-dimethyl-2,2'-bipyridine and two terminal Cl atoms. In the crystal structure, inter-molecular C-H?Cl hydrogen bonds link the mol-ecules. There are C-H?? contacts between the methyl groups and the pyridine and five-membered rings containing Zn(II) atoms; ?-? contacts also exist between the pyridine rings [centroid-centroid distances = 3.665?(5) and 3.674?(5)?Å].