Synthesis and spectral studies of 2-mercaptobenzimidazole derivatives. I

The syntheses of some 2-mercaptobenzimidazole (I) derivatives have been described. While preparing such compounds it has been observed that I reacts predominantly as the thione under anhydrous reaction conditions, and as the thiol in the presence of an alkali. Strutures of all of the nine compounds have been established with the help of spectral methods including ¹³C nmr spectroscopy of the two compounds (II and III).     

A simple and reliable semipreparative high-performance liquid chromatography technique for the isolation of marker-grade hyperforin from Hypericum perforatum L extract

The present work describes isolation of bioactive lipophilic constituent [namely, hyperforin from St. John's wort (Hypericum perforatum L.)], of approximately 98% purity by semipreparative high-performance liquid chromatography (LC). The extraction, isolation, and analysis of the collected compound is performed without the use of antioxidants and inert gas atmospheres at all the stages. Hyperforin, separated isocratically on a 12microm semiprep column, is obtained in high purity, lyophilized after the removal of the organic phase, and preserved at a low temperature. The purity of the collected marker compound is estimated by the use of LC-mass spectrometry and spectroscopic techniques.     

Isolation and biological evaluation of chromone alkaloid dysoline,a new regioisomer of rohitukine from Dysoxylum binectariferum

The chromone alkaloid dysoline (1), a new regioisomer of rohitukine (2) along with rohitukine and rohitukine-N-oxide (3) were isolated from the stem barks of Dysoxylum binectariferum. The structure of dysoline (1) was determined by extensive 2D-NMR studies and the absolute configuration was established by NOESY and CD spectra. Dysoline (1) consisted of a 5,7-dihydroxy-2-methylchromone nucleus substituted with a 2′-hydroxylated N-Me piperidine ring at the C-6 position. Dysoline differs from rohitukine by the position of the piperidine ring on the chromone nucleus. Dysoline displayed promising cytotoxicity in HT1080 fibrosarcoma cells with an IC₅₀ of 0.21 μM, and also displayed significant inhibition of proinflammatory cytokines TNF-α and IL-6.     

Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods

Pristine and WO₃ decorated TiO₂ nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO₂ NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO₂ NRs and thermally oxidised to obtain WO₃ nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO₂ NRs with WO₃.     

Flowerlike hybrid horseradish peroxidase nanobiocatalyst for the polymerization of guaiacol

In this study, the catalytic activity and stability of flowerlike hybrid horseradish peroxidase (HRP) nanobiocatalyst (HRP-Cu ²⁺ ) obtained from Cu ²⁺ ions and HRP enzyme in the polymerization reaction of guaiacol were analyzed. We demonstrated that HRP-Cu ²⁺ and hydrogen peroxide (H ₂ O ₂ ) initiator showed significantly increased catalytic activity and stability on the polymerization of guaiacol compared to that of free HRP enzyme. Poly(guaiacol) was observed with quite high yields (88%) and molecular weights (38,000 g/mol) under pH 7.4 phosphate-buffered saline (PBS) conditions at 60 °C with 5 weight% of HRP-Cu ²⁺ loading. HRP-Cu ²⁺ also shows very high thermal stability and works even at 70 °C reaction temperature; free HRP enzyme denatures at that temperature. Furthermore, HRP-Cu ²⁺ provided considerable repeated use and showed some degree of catalytic activity, even after the fourth recycle, in the polymerization of guaiacol.     

Chemical composition,antimicrobial, and lipase enzyme activity of essential oil and solvent extracts from Serapias orientalis subsp. orientalis

The volatile components of essential oil (EO), SPME, and SPME of solvent extracts ( n -hexane, methanol, and water) obtained from fresh Serapias orientalis subsp. orientalis ( Soo ) were analyzed by GC-FID/MS. EO of Soo gave 11 compounds in the percentage of 99.97%; capronaldehyde (37.01%), 2-( E )-hexenal (23.19%), and n -nonanal (19.05%) were found to be major constituents. SPME GC-FID/MS analyses of fresh plant and solvent extracts of Soo revealed 7, 12, 7, and 4 compounds within the range of 99.7% to 99.9%. Limonene (76.5%, 41.7%, and 61.3%) was the major compound in SPMEs of the n -hexane and methanol extracts. α -Methoxy- p -cresol (52.9%) was the main component in its water extract. The antimicrobial activity of EO and the solvent extracts of Soo were screened against 9microorganisms. EO showed the best activity against Mycobacterium smegmatis , with 79.5 µg/mL MIC value. The n -hexane, methanol, and water extracts were the most active against the Staphylococcus aureus within the range of 81.25–125.0 µg/mL (MIC). IC ₅₀ values for the lipase enzyme inhibitory activity of EO and solvent extracts ( n -hexane, methanol, and water) were determined to be 59.87 µg/mL, 64.03 µg/mL, 101.91 µg/mL, and 121.24 µg/mL, respectively.     

Synthesis and spectral studies of 2-mercapto-benzimidazole derivatives. II

This communication describes synthesis and spectral data of new 2-mercaptobenzimidazole derivatives.     

Observation of a molecular frame (e, 2e) cross section: an (e, 2e + M) triple coincidence study on H(2)

We report the first experimental results showing transition-specific anisotropy of molecular frame (e, 2e) cross sections. Vector correlations between the two outgoing electrons and the fragment ion have been measured for specific ionization-excitation processes of H2. The results enable us to obtain molecular frame (e, 2e) cross sections for transitions to the 2ssigma(g) and 2psigma(u) excited states of H(2)(+), thereby making stereodynamics of the electron-molecule collisions directly visible.     

Dilatometric studies of Purmandal clay: Part I

Clay from the Purmandal area of J&K State was separated into its different size fractions by the method of sedimentation and with Sharple's super centrifuge process. Dilatometric studies were performed on each clay fraction; the results obtained from the dilatation curves are discussed in detail. The results revealed that the finer fraction of clay is bentonitic in nature, whereas the other fractions are felsphatic and micaceous in nature.