Development of Odorless Thiols and Sulfides and Their Applications to Organic Synthesis

Summary. Development of new odorless thiols (dodecanethiol, 4-n-heptylphenylmethanethiol, 4-trimethylsilylphenylmethanethiol, 4-trimethylsilylbenzenethiol) and an odorless sulfide (1-methylsulfanyldodecane) and their applications to dealkylation, Michael addition, Swern oxidation, and Corey-Kim oxidation are described.     

Synthesis of a hairpin pyrrole-imidazole polyamide conjugate containing a quinone methide precursor and vinyl linking group

Standard procedures for elaborating a quinone methide precursor for conjugation to a DNA ligand was not compatible with the presence of a vinyl group. Instead, an acrylate linker was attached by Heck coupling subsequent to o-substitution of the phenolic precursor. This transformation required protection of the phenolic group and use of ethyl acrylate rather than acrylic acid. The presence of the vinyl group also rendered the quinone methide precursor more labile to alkaline conditions than its equivalent saturated derivative and required mild conditions for coupling to the pyrrole-imidazole polyamide.     

Gallium(III) halide-catalyzed coupling of indoles with phenylacetylene: synthesis of bis(indolyl)phenylethanes

Indoles undergo smooth coupling with phenylacetylene in the presence of 10 mol % of gallium(III) chloride or gallium(III) bromide under mild conditions to afford the corresponding 1,1-bis(1H-3-indolyl)-1-phenylethanes in high yields and with high selectivity.     

An Efficient Method for Agrobacterium-Mediated Genetic Transformation and Plant Regeneration in Cumin (Cuminum cyminum L.)

Cumin is an annual herbaceous medicinally important plant having diverse applications. An efficient and reproducible method of Agrobacterium-mediated genetic transformation was herein established for the first time. A direct regeneration method without callus induction was optimised using embryos as explant material in Gamborg’s B5 medium supplemented with 0.5-μM 6-benzyladenine and 2.0-μM α-naphthalene acetic acid. About 1,020 embryos (a mean of 255 embryos per batch) were used for the optimisation of transformation conditions. These conditions were an Agrobacterium cell suspension of 0.6 OD₆₀₀, a co-cultivation time of 72 h, 300-μM acetosyringone and wounding of explants using a razor blade. Pre-cultured elongated embryos were treated using optimised conditions. About 720 embryos (a mean of 180 embryos per batch) were used for transformation and 95 % embryos showed transient β-glucuronidase expression after co-cultivation. Putative transformed embryos were cultured on B5 medium for shoot proliferation and 21 regenerated plants were obtained after selection and allowed to root. T₀ plantlets showed β-glucuronidase expression and gene integration was confirmed via PCR amplification of 0.96 and 1.28 kb fragments of the hygromycin-phosphotransferase II and β-glucuronidase genes, respectively. In this study, a transformation efficiency of 1.5 % was demonstrated and a total of 11 transgenic plants were obtained at the hardening stage, however, only four plants acclimatised during hardening. Gene copy number was analysed by Southern blot analysis of hardened plants and single-copy gene integration was observed. This is the first successful attempt of Agrobacterium-mediated genetic transformation of cumin.     

Immunomagnetic nanoparticle based quantitative PCR for rapid detection of Salmonella

We have developed a rapid and sensitive method for immunomagnetic separation (IMS) of Salmonella along with their real time detection via PCR. Silica-coated magnetic nanoparticles were functionalized with carboxy groups to which anti-Salmonella antibody raised against heat-inactivated whole cells of Salmonella were covalently attached. The immuno-captured target cells were detected in beverages like milk and lemon juice by multiplex PCR and real time PCR with a detection limit of 10⁴ cfu.mL^?1 and 10³ cfu.mL^?1, respectively. We demonstrate that IMS can be used for selective concentration of target bacteria from beverages for subsequent use in PCR detection. PCR also enables differentiation of Salmonella typhi and Salmonella paratyphi A using a set of four specific primers. In addition, IMS—PCR can be used as a screening tool in the food and beverage industry for the detection of Salmonella within 3–4 h which compares favorably to the time of several days that is needed in case of conventional detection based on culture and biochemical methods.

Catalytic behavior of decomposed molybdophosphoric acid supported on alumina for oxidative dehydrogenation of ethane to ethylene

Oxidative dehydrogenation of ethane (ODHE) to ethylene was investigated over a series of alumina supported molybdophosphoric acid (MPA) catalysts. The MPA was transformed into surface Mo oxides on Al₂O₃ when subjected to calcination at 600°C. The catalysts were characterized by N₂-adsorption, XRD, FT-IR spectroscopy and TPR techniques. The results showed that MPA loading and the source of Mo precursor had a clear influence on the catalytic performance. The evaluation of the catalysts for ODHE at temperatures between 450 and 550°C revealed superior ethane conversion (X～24%) and ethylene selectivity (S = ca. 65%) over 20 wt % MPA/Al₂O₃ catalyst. The transformation of MPA into finely dispersed Mo oxides on Al₂O₃ appeared to be responsible for this improved performance.     

Carrier facilitated transport of thorium from HCl medium using Cyanex 923 in n-dodecane containing supported liquid membrane

Present studies deal with supported liquid membrane (SLM) technique for the separation of thorium from hydrochloric acid (HCl) medium using Cyanex 923 as a carrier. Effects of feed acidity, strippant, and membrane pore size and membrane thickness on the transport of thorium have been studied in detail. The optimized parameters were applied for separation of thorium from a radioanalytical waste. Stability of the membrane and membrane support was investigated. Transport of thorium increased from 78.3 to about 93.7 % with increase in acidity from 0.5 to 2 M using 0.3 M Cyanex 923 in n-dodecane as carrier and 2 M ammonium carbonate as stripping phase. The transport of thorium decreased above 2 M HCl. An attempt was made to model the physicochemical transport of thorium in SLM and understand the mechanism of thorium transport.     

A Novel and Efficient One Pot Synthesis of 2,4‐Disubstituted Thiazoles and Oxazoles Using Phenyltrimethylammoniumtribromide in Ionic Liquid

A novel and efficient one‐pot procedure has been described for synthesis of 2,4‐disubstituted thiazoles and oxazoles from substituted ketones using phenyltrimethylammoniumtribromide as in situ brominating agent followed by reaction with thioamide/thiourea and amides/ureas, respectively in [bmim][BF₄] ionicliquid. The advantages of the procedure include avoiding the handling of lacrymetric compounds, hazardous and toxic organic solvents along with good to excellent yield of the products.     

Modulation of Photochemical Damage in Normal and Malignant Cells by Naturally Occurring Compounds†

Certain phytochemicals, such as the stilbene, resveratrol (RES, found in red grapes and berries), and the triterpenoid, ursolic acid (UA, found in waxy berries and herbs such as rosemary and oregano), have antioxidant, anti‐inflammatory and antiproliferative effects. Two human‐derived cell lines, hTERT‐RPE with a nonmalignant phenotype derived from retinal pigment epithelium, and ATCC CRL‐11147 derived from a malignant skin melanoma, were used as in vitro models of photooxidative stress produced by exposure to the broadband output of a 150 W Hg vapor arc lamp at an irradiance of 19–26 mW cm^?2. In untreated cells, UV–VIS broadband light exposure produced a loss of proliferative ability, an activation of NF‐κB and an increase in protein carbonyl adducts at 24 h postexposure. Pretreatment of the cells with RES or UA at 1–2 μm significantly reduced the amount of phosphorylated NF ‐κB at 24 h postexposure. RES pretreatment reduced the burden of light‐induced protein carbonyl adducts by up to 25% in exposed cells. UA treatment markedly increased the sensitivity of melanoma cells to UV radiation, while conferring some photoprotection to RPE cells. These observations indicate that phytochemicals modulate the cellular response to photochemical stress by interacting with specific cell‐signaling pathways.     

Extraction of cesium-137 from nitric acid medium in the presence of macrocyclic polyethers

Extraction behavior of¹³⁷Cs was studied from nitric acid medium using dibenzo 18 crown 6 (DB18C6), 4,4'(5')di-acetylbenzo 18 crown 6 (DAB18C6), 4, 4'(5')di-hexanoylbenzo 18 crown 6 (DHB18C6), 4,4'(5')di-nonanoylbenzo 18 crown 6 (DNB18C6) and 4,4'(5')di-t-butylbenzo 18 crown 6 (DTBB18C6) in nitrobenzene medium. The stoichiometry of the species extracted with dibenzo 18 crown 6 (L) conformed to ML⁺. NO₃ ⁻ TheD _Cs values were found not to be affected by the presence of aluminium nitrate in the aqueous phase. The separation behavior of fission products obtained from an irradiated natural uranium target was also studied. Presence of 0.004M phosphotungstic acid found to enhance theD _Cs values at lower acidities.