Structure and spectral properties of L-histidinium dipicrate dihydrate

Non-linear optical active L-histidinium dipicrate dihydrate (LHDD) single crystals were grown by slow evaporation method. The Fourier transform FT-IR, FT-Raman, (1)H and (13)C NMR spectra of the crystal have been recorded and analysed. The spectral analyses confirm the formation of the compound and the stoichiometry. The geometry and spectral characteristics were examined using the density functional theory (DFT) method, B3LYP with 6-31G(d,p) basis set. The first-order hyperpolarisability, energies of frontier molecular orbitals and the Mulliken population analysis were also calculated. The HOMO-LUMO energy gap value 2.73 eV indicates the charge transfer from picrate to histidinium through the hydrogen bond. The second-order NLO properties of the molecule are studied by Kurtz-Perry powder technique. SHG efficiency of the compound is nearly 2.5 times greater than KDP. Theoretical calculations indicate hyperpolarisability of LHDD is 39 times greater than urea. The results show that the title molecule can be used for opto-electronic applications.

Theoretical studies on the quinoidal thiophene based dyes for dye sensitized solar cell and NLO applications

The designed quinoidal thiophene molecules are good candidates for DSSC applications.

Expression of angiotensin II and its receptors in cyclosporine-induced gingival overgrowth

BACKGROUND AND OBJECTIVES

The renin-angiotensin system (RAS) is considered as a hormonal circulatory system involved in maintaining blood pressure, electrolyte and fluid homeostasis. RAS components can be synthesized in local tissues and are found to play a role in gingival overgrowth. The drug-induced gingival overgrowth (DIGO) is a fibrotic condition, which is associated with multiple factors, including inflammation and adverse drug effects such as cyclosporine A. This study was directed forward to the identification of the angiotensinogen, angiotensin II (Ang II) and its receptors AT₁ /AT₂ expression in DIGO tissues and cyclosporine-treated human gingival fibroblast cells.

MATERIAL AND METHODS

Gingival samples were obtained from patients with cyclosporine-induced gingival overgrowth, chronic periodontitis and normal healthy subjects. The total RNA was isolated and reverse transcription-polymerase chain reaction was performed for angiotensinogen, Ang II and AT₁ /AT₂ receptor. Ang II protein was estimated from tissue by enzyme immunoassay. The expression of Ang II and its receptors were also examined in gingival fibroblast cells treated with cyclosporine.

RESULTS

Ang II mRNA and protein expression was significantly higher in patients with DIGO than in patients with periodontitis and healthy subjects. The AT₁ mRNA was expressed more than AT₂ in all examined tissues. In gingival fibroblasts, Ang II and AT₁ expressions were increased with cyclosporine incorporation compared to controls.

CONCLUSION

These results suggest that cyclosporine can modulate local expression of RAS components such as angiotensinogen, Ang II and its receptors in gingival tissues and gingival fibroblast cells.

Effect of diallyl disulfide on insulin-like growth factor signaling molecules involved in cell survival and proliferation of human prostate cancer cells in vitro and in silico approach through docking analysis

PURPOSE

Diallyl Disulfide (DADS) is one of the major components of garlic, which inhibits the proliferation of various cancer cells. Our previous studies showed that DADS inhibits cell growth and induces apoptosis on prostate cancer cells. Insulin like growth factor signaling pathway plays a significant role on prostate cancer cell growth and survival and it's over expression also identified in human prostate cancers. The molecular mechanism of IGF mediated PI3K/Akt signaling remains to be elucidated. The present study was designed to evaluate the effects of diallyl disulfide on IGF signaling in androgen independent prostate cancer cells (PC-3).

METHODS

DADS (10-50 μM) caused dose-dependent inhibition of PC-3 cells, were analyzed by MTT, IC50 value of PC-3 cells was 40 μM for 24h. Interestingly, DADS also altered the mRNA and protein expressions of IGF signaling and apoptotic molecules which were confirmed by semi quantitative PCR and western blot method. Further the docking study of DADS with IGF receptor was carried out by Ligand Fit of Discovery studio. Accord Excel Package was used for the prediction of ADME properties of the compound.

RESULTS

The results suggests that DADS decreases the survival rate of androgen independent prostate cancer cells by modulating the expression of IGF system, which leads to inhibition of phosphorylation of Akt, thereby inhibits cell cycle progression and survival by lowering the expression of cyclin D1, NFkB and anti-apoptotic Bcl-2 molecule and increasing the level of pro-apoptotic (Bad and Bax) signaling molecules which leads to apoptosis.

CONCLUSION

The present investigation showed downregulation of Akt and a concomitant increase in apoptosis in DADS treated prostate cancer cells. Since inhibition of this Akt pathway by DADS leads to inhibition in cancer cell progression, it is highly suggested that DADS has the potential use as a therapy for prostate cancer.

Reaction mechanism and kinetics of the atmospheric oxidation of 1,4-thioxane by NO3 — A theoretical study

Volatile organic compounds (VOCs) are emitted as pollutants into the atmosphere from many natural and artificial sources. The oxidation of VOCs by atmospheric species plays a key role in the degradation of VOCs. In the present investigation, the atmospheric degradation of a cyclic organosulfur compound, 1,4-thioxane, by an NO3• radical is studied. Pathways for the reaction of 1,4-thioxane with the NO3• radical were modeled through electronic structure calculations using density functional theory methods B3LYP, M06-2X, and MP2 with the 6–31G(d,p) basis set. The NO3•-initiated reaction of 1,4-thioxane was found to proceed in three ways: by single-hydrogen atom abstraction, by direct transfer of the O atom of NO3• to the S atom moiety of 1,4-thioxane, or by two-hydrogen atom transfer reactions leading to the formation of a peroxy radical intermediate, which further undergoes secondary reactions with other atmospheric species. Structures, energies, and vibrational frequencies obtained from M06-2X/6–31G(d,p) electronic structure calculations were subsequently used to perform canonical variational transition-state theory calculations to determine the rate constants over the temperature range of 278–350 K and to study the lifetime of 1,4-thioxane in the atmosphere. The rate constant calculated for the reaction of 1,4-thioxane with the NO3• radical is in good agreement with the available experimental data.

Optical absorption and emission properties of fluoranthene, benzo[k]fluoranthene, and their derivatives. A DFT study

Fluoranthene and benzo[k]fluoranthene-based oligoarenes are good candidates for organic light-emitting diodes (OLEDs). In this work, the electronic structure and optical properties of fluoranthene, benzo[k]fluoranthene, and their derivatives have been studied using quantum chemical methods. The ground-state structures were optimized using the density functional theory (DFT) methods. The lowest singlet excited state was optimized using time-dependent density functional theory (TD-B3LYP) and configuration interaction singles (CIS) methods. On the basis of ground- and excited-state geometries, the absorption and emission spectra have been calculated using the TD-DFT method with a variety of exchange-correlation functionals. All the calculations were carried out in chloroform medium. The results show that the absorption and emission spectra calculated using the B3LYP functional is in good agreement with the available experimental results. Unlikely, the meta hybrid functionals such as M06HF and M062X underestimate the absorption and emission spectra of all the studied molecules. The calculated absorption and emission wavelength are more or less basis set independent. It has been observed that the substitution of an aromatic ring significantly alters the absorption and emission spectra.