Development of energetic pharmacophore for the designing of 1,2,3,4-tetrahydropyrimidine derivatives as selective cyclooxygenase-2 inhibitors

We present here the Energetic pharmacophore model representing complementary features of the 1,2,3,4-tetrahydropyrimidine for selective cyclooxygenase-2 (COX-2) inhibition. For the development of pharmacophore hypothesis, a total of 43 previously reported compounds were docked on active site of COX-2 enzyme. The generated pharmacophore features were ranked using energetic terms of Glide XP docking for 1,2,3,4-tetrahydropyrimidine scaffold to optimize its structure requirement for COX-2 inhibition. The thirty new 4,5,6-triphenyl-1,2,3,4-tetrahydropyrimidine derivatives were synthesized and assessed for selective COX-2 inhibitory activity. Two compounds 4B1 and 4B11 were found to be potent and selective COX-2 inhibitors. The molecular docking studies revealed that the newly synthesized compounds can be docked into COX-2 binding site and also provide the molecular basis for their activity.     

Radiation inactivation study of aminopeptidase: probing the active site

Ionizing radiation inactivated purified chicken intestinal aminopeptidase in media saturated with gases in the order N₂O>N₂>air. The D₃₇ values in the above conditions were 281, 210 and 198 Gy, respectively. OH radical scavengers such as t-butanol and isopropanol effectively nullified the radiation-induced damage in N₂O. The radicals (SCN)₂^•−, Br₂^•− and I₂^•− inactivated the enzyme, pointing to the involvement of aromatic amino acids and cysteine in its catalytic activity. The enzyme exhibited fluorescence emission at 340 nm which is characteristic of tryptophan. The radiation-induced loss of activity was accompanied by a decrease in the fluorescence of the enzyme suggesting a predominant influence on tryptophan residues. The enzyme inhibition was associated with a marked increase in the K_m and a decrease in the V_max and k_cat values, suggesting an irreversible alteration in the catalytic site. The above observations were confirmed by pulse radiolysis studies.     

Theory of extreme correlations using canonical Fermions and path integrals

The  t$t$–J$J$  model is studied using a novel and rigorous mapping of the Gutzwiller projected electrons, in terms of canonical electrons. The mapping has considerable similarity to the Dyson–Maleev transformation relating spin operators to canonical Bosons. This representation gives rise to a non Hermitian quantum theory, characterized by minimal redundancies. A path integral representation of the canonical theory is given. Using it, the salient results of the extremely correlated Fermi liquid (ECFL) theory, including the previously found Schwinger equations of motion, are easily rederived. Further, a transparent physical interpretation of the previously introduced auxiliary Greens function and the ‘caparison factor’, is obtained.     

Proton spectroscopy of 96Tc from the (3He,d) reaction

Energy levels of the even-mass odd nucleus ⁹⁶Tc have been populated with the ⁹⁵Mo(³He, d)⁹⁶Tc reaction at a bombarding energy of 33.6 MeV and with 28 keV resolution (FWHM). Thirty levels were observed below 2.10 MeV excitation. Comparison of experimental angular distributions with DWBA calculations allowed l-value assignments and the extraction of spectroscopic factors for most levels. Over eighty-five percent of the observed spectroscopic strength is located in the lowlying $\text{π1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{-}\text{v}\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ configuration multiplet. A simple residual interaction shell model calculation reproduces the observed low-lying positive parity multiplet relatively well although the experimental spectrum indicates much configuration mixing is present.     

Directional correlation measurements in69Ga

Gamma-gamma directional correlation measurements have been made on the 553.35-318.63, 234.79–871.98 and 1,052.02-871.98 keV cascades in⁶⁹Ga from the decay of⁶⁹Ge using a NaI(Tl)-Ge(Li) coincidence set up. On the basis of these measurements the spin parity of 1/2^?, 3/2^?, 3/2^? and 5/2^? have been assigned respectively to the 318.63, 871.98, 1,106.77 and 1,924.00 keV states in⁶⁹Ga. The results have been discussed and compared with the previous works.     

Kinetic antiferromagnetism in the triangular lattice

We show that the motion of a single hole in the infinite-U Hubbard model with frustrated hopping leads to weak metallic antiferromagnetism of kinetic origin. An intimate relationship is demonstrated between the simplest versions of this problem in one and two dimensions, and two of the most subtle many body problems, namely, the Heisenberg Bethe ring in one dimension and the two-dimensional triangular lattice Heisenberg antiferromagnet.     

A new strongly-bound chemisorption structure of benzene on Si(100)

Using Scanning Tunneling Microscopy (STM) and ab initio theory we identify a new chemisorbed structure of benzene on Si(100) which we term ‘inter-dimer butterfly,’ ID-BF (C). This involves di-σ-bonding of benzene to two adjacent Si-dimers of a single dimer-row. This configuration is always found in association with a C-type defect, as shown by STM images taken immediately before formation or after elimination of the ID-BF (C) adsorbate. Ab initio calculations yield a binding energy of 2.4 eV for this new structure, higher than the binding energies of other possible chemisorbed configurations of benzene.