Design, synthesis, and properties of new derivatives of pentacene

Stable, soluble ethynylated derivatives of pentacene (9a-c) were synthesized, and the ethynyl moieties on the terminal rings were used to tune the electronic properties of these compounds. Their oxidation potentials are higher and their reduction potentials are lower than those of pentacene. The HOMO-LUMO gaps are among the lowest reported for pentacene derivatives.     

Will relativistic heavy-ion colliders destroy our planet?

Experiments at the Brookhaven National Laboratory will study collisions between gold nuclei at unprecedented energies. The concern has been voiced that “strangelets” – hypothetical products of these collisions – may trigger the destruction of our planet. We show how naturally occurring heavy-ion collisions can be used to derive a safe and stringent upper bound on the risk incurred in running these experiments.     

Fine structure of poly(vinylidene fluoride) membranes prepared by phase inversion from a water/N‐methyl‐2‐pyrollidone/poly(vinylidene fluoride) system

Poly(vinylidene fluoride) (PVDF) membranes were prepared by the isothermal immersion and precipitation of PVDF/N‐methyl‐2‐pyrollidone dope solutions in either harsh or soft nonsolvent baths. Low‐voltage field emission scanning electron microscopy imaging of the formed membranes at high magnifications (e.g., 300,000×) revealed their nanoscale fine structures, particularly dendrites observed on the surfaces of the macrovoids, cellular pores, and the membrane skin, which have never been successfully presented in the literature. Evidence of crystallization was also demonstrated by X‐ray diffraction and differential scanning calorimetry measurements. The phase diagram at 25 °C, including a binodal, tie lines, and a crystallization‐induced gelation line, was determined both experimentally and theoretically. These results were further used in mass‐transfer calculations to obtain diffusion trajectories and concentration profiles for the membrane region, which were useful for elucidating the relationship between the membrane preparation conditions and the obtained membrane morphologies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 830–842, 2004     

Crystal structure of 2,3-diaza-1,3-diphenylpropene.

The title compound crystallizes in monoclinic space group P2(1)/c. There are two molecules in the asymmetric unit. While one of these molecules is in a general position, the other is in disordered position. The angle between the directions of the molecules in the asymmetric unit is 87.5(1) degrees.     

Optimization of Adventitious Root Culture for Production of Biomass and Secondary Metabolites in Prunella vulgaris L.

Adventitious root cultures of Prunella vulgaris L. were established in shaking flask system for the production of biomass and secondary metabolites. Adventitious root cultures were induced from callus cultures obtained from leaf explants on solid Murashige and Skoog (MS) medium containing combination of 6-benzyladenine (BA; 1.0 mg l^?1) and naphthalene acetic acid (NAA; 1.5 mg l^?1). Thereafter, 0.49 g inoculum was transferred to liquid MS medium supplemented with different concentrations of NAA (0.5–2.0 mg l^?1). Growth kinetics of adventitious roots was recorded with an interval of 7 days for 49 days period. Highest biomass accumulation (2.13 g/l) was observed in liquid medium containing 1.0 mg l^?1 NAA after 21 days of inoculation. However, other concentrations of NAA also showed similar accumulation pattern but the biomass gradually decreases after 49 days of inoculation. Adventitious roots were collected and dried for investigation of total phenolics (TP), total flavonoids (TF), and antioxidant activities. Higher TPC (0.995 GAE mg/g-DRB) and TFC (6.615 RE mg/g-DRB) were observed in 0.5 mg l^?1 NAA treated cultures. In contrast, higher antioxidant activity (83.53 %) was observed 1.5 mg l^?1 NAA treated cultures. These results are helpful in up scaling of root cultures into bioreactor for secondary metabolites production.     

Synergistic Effects of Drought Stress and Photoperiods on Phenology and Secondary Metabolism of Silybum marianum

Silybum marianum is an important medicinal plant of the family Asteraceae, well known for its set of bioactive isomeric mixture of secondary metabolites “silymarin”, primarily acting as a hepato-protective agent. Abiotic stress augments plant secondary metabolism in different plant tissues to withstand harsh environmental fluctuations. In the current study, our aim was to induce drought stress in vitro on S. marianum under the influence of different photoperiod treatments to study the effects, with respect to variations in secondary metabolic profile and plant growth and development. S. marianum was extremely vulnerable to different levels of mannitol-induced drought stress. Water deficiency inhibited root induction completely and retarded plant growth was observed; however, phytochemical analysis revealed enhanced accumulation of total phenolic content (TPC), total flavonoid content (TFC), and total protein content along with several antioxidative enzymes. Secondary metabolic content was positively regulated with increasing degree of drought stress. A dependent correlation of seed germination frequency at mild drought stress and antioxidative activities was established with 2 weeks dark?+?2 weeks 16/8 h photoperiod treatment, respectively, whereas a positive correlation existed for TPC and TFC when 4 weeks 16/8 h photoperiod treatment was applied. The effects of drought stress are discussed in relation to phenology, seed germination frequency, biomass build up, antioxidative potential, and secondary metabolites accumulation.     

Purification and Characterization of Calreticulin: a Ca2+-Binding Chaperone from Sheep Kidney

Calreticulin (CRT) is a molecular chaperone with a molecular mass of 46 kDa present in the endoplasmic reticulum (ER). This protein is primarily involved in the regulation of intracellular Ca²⁺ homeostasis and Ca²⁺ storage in the ER. CRT also plays a significant role in autoimmunity and cancer. This protein contains three distinct structural domains with specialized functions. Here, we are reporting a simple procedure for the purification of CRT from mammalian kidney. To isolate CRT,  sheep kidney was crushed and kept for 12 h in the extraction buffer. The lysate was centrifuged, and supernatant was precipitated by ammonium sulphate. The precipitate of 90 % ammonium sulphate was extensively dialyzed and loaded on DEAE-Hi-Trap FF and Mono Q chromatography columns. The purity of CRT was confirmed by SDS-PAGE. Finally, the protein was identified by matrix-assisted laser desorption/ionization time of flight. The purified protein was further characterized for secondary structural elements using the far-UV circular dichroism measurements. Our purification procedure is fast and simple with high yield.     

Hydrated ferric sulfate catalyzed synthesis of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives through one-pot reaction

A wide variety of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives (4a–z) were synthesized through a one-pot three-component reaction from indoles, aromatic aldehydes, and thiols at room temperature using hydrated ferric sulfate as a Lewis acid catalyst. The key features of the present protocol are mild and simple reaction procedure, moderate to good yields, requirement of inexpensive and reusable catalyst, no formation of dithioacetals derivatives from the corresponding aldehydes as well as bis-(indolyl) methane derivatives.     

Design,synthesis, and anticancer evaluation of acetamide and hydrazine analogues of pyrimidine

A library of acetamide and hydrazine analogues were generated on the pyrimidine ring through a multistep reaction starting from 5-nitro-pyrimidine-4,6-diol and pyrimidine-4,6-diol, respectively. The synthesized analogues were screened for in vitro cytotoxic activity against various human cancer cell lines like HCT-1 and HT-15 (colon), MCF-7(breast), PC-3 (prostrate), SF268 (CNS) using MTT method. From the bioassay results, it was observed that even though many of the synthesized derivatives exhibited a good potency against various screened cancer cell lines, compound 14a from the acetamide series was found to show potent anticancer activity on all the tested cancer cell lines with IC₅₀ value of 0.36μM on CNS cell line and 1.6μM on HT-21 cell line, and compound 19xxi from hydrazine series of pyrimidine showed potent activity against three tested cancer cell lines with IC₅₀ value of 0.76μM on HT-29 cell line, 2.6μM on HCT-15, and 3.2μM on MCF-7 cell line.