Virtual Screening,Synthesis and Biological Evaluation of Streptococcus mutans Mediated Biofilm Inhibitors

Dental caries, a global oral health concern, is a biofilm-mediated disease. Streptococcus mutans, the most prevalent oral microbiota, produces extracellular enzymes, including glycosyltransferases responsible for sucrose polymerization. In bacterial communities, the biofilm matrix confers resistance to host immune responses and antibiotics. Thus, in cases of chronic dental caries, inhibiting bacterial biofilm assembly should prevent demineralization of tooth enamel, thereby preventing tooth decay. A high throughput screening was performed in the present study to identify small molecule inhibitors of S. mutans glycosyltransferases. Multiple pharmacophore models were developed, validated with multiple datasets, and used for virtual screening against large chemical databases. Over 3000 drug-like hits were obtained that were analyzed to explore their binding mode. Finally, six compounds that showed good binding affinities were further analyzed for ADME (absorption, distribution, metabolism, and excretion) properties. The obtained in silico hits were evaluated for in vitro biofilm formation. The compounds displayed excellent antibiofilm activities with minimum inhibitory concentration (MIC) values of 15.26–250 µg/mL.     

Development and validation of a selective online dissolution method for rosiglitazone maleate

A new specific, accurate, precise, and reproducible selective online dissolution method for rosiglitazone maleate is developed and validated for the dissolution of rosiglitazone maleate in pharmaceutical formulations. The rationale of the method is based on the direct measurement of the absorbance of the analyte in the buffer medium at 242 nm using buffer as blank. Dissolution is achieved on a dissolution test apparatus consisting of photo diode array spectrophotometer, peristaltic pump, and temperature controller, using 0.01N HCl and 0.05M potassium chloride as the dissolution medium. The proposed method is developed, optimized, and validated in terms of linearity, reproducibility, accuracy, and selectivity for the dissolution of rosiglitazone maleate in pharmaceutical formulations. The method is found to be linear in the range of 1 to 14 microg/mL of rosiglitazone maleate with a correlation coefficient of 0.999. The dissolution studies of rosiglitazone maleate tablets obtained by the proposed method are in good agreement with those by high-performance liquid chromatography.     

Synthesis and characterization of some methyl complexes of palladium(II). Part 2(1)

Summary Dichloro complexes of Pd^II, [Pd(L–L)Cl₂], where L–L=1-(thiomethyl)-2-(diphenylarsino)ethane (S–As) or 1-(thiomethyl)-2-(diphenylphosphino)ethane (S–P) andtrans-[PdL₂Cl₂], where L=diphenyl(2-phenylethyl)-phosphine (PE), diphenyl(1-naphthyl)phosphine (PN) orN-methyl-2-thiophenealdimine (SN), have been prepared and characterized. The reactions of these complexes with MeLi were investigated. The dimethyl complexes [Pd(L–L)Me₂] (L–L=S–As, S–P) and [Pd(PE)Me₂] were isolated and characterized. Reaction of [Pd(L–L)Me₂] (L–L=S–As, S–P) with HCl affords the monomethyl derivatives [Pd(L–L)Me(Cl)]. In contrast to the Pt analogues, [Pd(L–L)Me₂] and [Pd(L–L)Me(Cl)] are relatively less stable than [Pt(L–L)Me₂] and [Pt(L–L)Me(Cl)].     

Hyperfine structure studies of Tantalum

A narrow bandwidth ring dye laser pumped by an argon ion laser has been used to investigate the hyperfine structure of the even and odd parity levels of tantalum by optogalvanic spectroscopy in the wavelength range 5640 to 6050 Å. Seventeen transitions have been observed and eight of these have not been reported in the literature so far. These transitions involve 27 levels with 15 odd and 12 even parity configurations. The magnetic dipole hyperfine interaction constants A and the electric quadrupole interaction constants B for these levels have been computed and compared with the data available in literature. The results for the levels at 34799.71 cm^?1, 26960.46 cm^?1 and 19657.78 cm^?1 are reported for the first time.     

Selective adsorption of thorium on activated charcoal from electrolytic aqueous solution

The adsorption of thorium on activated charcoal has been studied as a function of shaking time, amount of adsorbent, pH, concentration of adsorbate and temperature. Adsorption of thorium obeys the Langmuir isotherm. H⁰ and S⁰ were calculated from the slope and intercept of ln K_D vs. 1/T plots. The influence of different anions and cations on thorium adsorption has been examined. The adsorption of other metal ions on activated charcoal has been studied under specified conditions to check its selectivity. Consequently, thorium was removed from Cs, Co, Ba, Cr, Sr, Cd, Cu, Mn and Zn. More than 98% adsorbed thorium on activated charcoal can be recovered with 55 ml 3M HNO₃ solution. Wavelength dispersive X-rays fluorescence spectrometer was used for measuring thorium concentration.     

In-vitro drug–drug interaction studies of diltiazem with floroquinolones

Diltiazem is an established cardiovascular drug mainly used for the management of hypertension specifically for the angina pectoris. Fluoroquinolones are widely prescribed against the treatment of severe infections. In vitro relations of diltiazem with fluoroquinolones (ciprofloxacin, levofloxacin, norfloxacin, and ofloxacin) were examined using spectrophotometric and separation techniques, i.e., RP-HPLC. Diltiazem’s availabilities were observed to be predisposed highly in the presence of fluoroquinolones. To investigate the mechanism of interaction in a variety of dissolution environments, i.e., simulating body environments with regard to pH on these interactions has been studied. Moreover, complex of diltiazem–fluoroquinolones were prepared and elucidated through IR spectroscopy and confirmed by computational molecular modeling.     

Characterization of the short-chain branches in poly(vinyl chloride)s by γ irradiation of the reduced polymers

The volatile products from the γ irradiation of samples of poly(vinyl chloride) prepared under different conditions and reduced to the corresponding polyethylenes have been measured quantitatively and compared with those for low- and high-density polyethylenes and copolymers of ethylene with small amounts of α-olefins. The presence of methyl branches is clearly demonstrated and there is also evidence for ethyl and butyl branches, although these had not been considered significant in previous [¹³C] NMR studies. The method is shown to be extremely sensitive to small quantities of residual trialkyl tin hydride reductant occluded in, and possibly also reacted with, the polymer, and to residual chlorine (<0.5%). The yields of alkanes are higher than expected from the branch frequencies determined by i.r. and [¹³C] NMR and results for ethylene-α-olefin copolymers. This difference is apparently due to sensitisation of the radiation degradation by residual chlorine and reductant. Quantitative determinations of branch frequencies by the radiolytic method are unlikely to be obtained until these problems are overcome.     

Nitriding molybdenum： Effects of duration and fill gas pressure when using lO0-Hz pulse DC discharge technique

Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM） are used for the structural and morphological analysis of the nitrided layers. Vickers＇ microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar （1 bar = 105 Pa）. A considerable increase in surface microhardness （approximately by a factor of 2） is observed for longer duration （10 h） and 2-mbar pressure. Longer duration （10 h） and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.