Synthesis,characterization, electrochemistry and evaluation of biological activities of some ferrocenyl Schiff bases

Synthesis of ferrocenyl Schiff bases ( 1–6 ) was carried out by the condensation reaction of 4‐ferrocenyl aniline with different substituted aromatic aldehydes and acetyl acetone. Compounds were characterized by physical measurements, elemental analysis, FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopy. Single crystal X‐ray analysis of compound 2 showed the co‐planarity of both aromatic rings connected by a C–N double bond. Compounds demonstrated reversible one‐electron redox behavior and their peak currents were found to increase linearly with the square root of the sweep rate ν^1/2. The overall electrode processes were found to be diffusion controlled. Compounds 1 and 4 showed low cytotoxicity and appreciable antifungal, antioxidant and DNA protection activities. Copyright © 2010 John Wiley & Sons, Ltd.     

Inelastic deformations of stainless steel leaf springs-experiment and nonlinear analysis

A stainless steel leaf spring is designed and constructed followed by its performance evaluation by experiment and non-linear analysis so that an insight into the optimum use of material can be made. Cantilever beams of uniform strength, popularly termed as leaf springs, undergo much larger deflections in comparison to a beam of constant cross-section; that needs inclusions of geometric non-linearity for rigorous analysis. This study deals with such a cantilever beam, but takes into account the material non-linearity as well. Experiments were conducted for such a cantilever beam, with highly non-linear stress-strain curves. In addition to the experiment, a computer code in ‘C’ has been developed using the Runge-Kutta technique for the purpose of simulation. Effective modulus-curvature relations are obtained from the non-linear stress-strain relations for different sections of the beam and used for the analysis. It is seen that non-linear stress-strain curve governs the bending of the beam. Importantly, non-linear analysis shows the stresses are not so high as predicted by the linear theory without end-shortening. Moreover, the tensile and compressive stresses are different in magnitude and both decrease along the span. Experimental load-deflection curves are found to be initially concave upward but, non-linear and convex upward at a high load. Comparison of the numerical results with the available experimental results from another research group and theory shows excellent agreement verifying the soundness of the entire numerical simulation scheme.     

Development of an HPTLC‐based diagnostic method for invasive aspergillosis

A rapid, sensitive and specific high‐performance thin‐layer chromatographic (HPTLC) method was developed and validated for determination of gliotoxin in Aspergillus infected immunocompromised patients with invasive aspergillosis (IA). Densitometric analysis of gliotoxin was carried out in the absorbance mode at 254 nm after single‐step extraction with chloroform. The method uses TLC aluminum plates pre‐coated with silica gel 60F‐254 as a stationary phase and toluene–isoamyl alcohol–methanol (10:0.5:0.5, v/v/v) as mobile phase, which gives compact spot of gliotoxin (R_f = 0.51). The calibration curve was linear (r² ≥ 0.994) between peak area and concentration in the tested range of 100–1000 ng spot^?1 with minimum detectable range 0.025 ng μ^?1 of serum sample. The mean ± SD value of slope and intercept of the standard chromatogram of gliotoxin were found to be 523.2 ± 1.555635 and 915.8 ± 30.68843, respectively. The developed method is simple, rapid, precise and less costly than earlier diagnostic methods, and different serum samples can be run on a single TLC plate for comparative analysis. The proposed method can be used to analyze gliotoxin in patient serum for easy, rapid and cost‐effective diagnosis of IA. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel antimicrobial flavonoidic glycoside from the leaves of Alstonia macrophylla Wall ex A. DC (Apocynaceae)

<正>A new flavonoidic glycoside,tricin-4'-O-β-L-arabinoside(1) was isolated from the leaves of Alstonia macrophylla along with two known flavonoids,vitexin and myricetin-3′-rhamnoside-3-O-galactoside.Their structures were established by chemical and spectral evidences.The known compounds were reported for the first time from this plant.Moreover compound 1 was tested for antifungal and antibacterial activities.     

Stability‐indicating HPTLC method for quantitative estimation of silybin in bulk drug and pharmaceutical dosage form

In the present study a novel stability‐indicating high‐performance thin‐layer chromatography (HPTLC) method for quantitative determination of silybin in bulk drug and nanoemulsion formulation has been developed and validated on silica using solvent chloroform–acetone–formic acid (9 : 2 : 1 v/v/v) (R_f of silybin 0.46 ± 0.05) in the absorbance mode at 296 nm. The method showed a good linear relationship (r² ± 0.999) in the concentration range 25–1500 ng per spot. It was found to be linear, accurate, precise, specific, robust and stability‐indicating and can be applied for quality control and standardization of several multi‐component hepatoprotective formulations as well as for stability testing of different dosage forms. The method proposed was also used to investigate the kinetics of acidic and alkaline degradation processes by quantification of drug at different temperature to calculate the activation energy and half‐life for silymarin degradation. Copyright © 2009 John Wiley & Sons, Ltd     

Kinetics and mechanism of oxidation of N,N-bis(salicylaldehyde-1,2-diaminoethane) cobalt(II) by N-bromosuccinimide in aqueous acidic medium

The kinetics of oxidation of N,N-bis(salicylaldehyde-1,2-diaminoethane) cobalt(II) complex by N-bromosuccinimide (NBS) in aqueous acid and H₂O–MeOH solvent mixtures were studied spectrophotometrically over the 20–40 °C range, 0.1–0.5 mol dm^?3 ionic strength, 2.2–2.8 pH range and 0–40 wt% MeOH–H₂O solvent mixtures for a range of NBS and complex concentrations. The rate shows first-order dependence on both [NBS] and [complex] and decreases with pH over the range studied. The protonated form of N-bromosuccinimide was identified as the main reactive species. An inner-sphere mechanism involving free radicals is proposed.     

Theoretical studies of structural and magnetic properties of cubic perovskites PrCoO3 and NdCoO3

The structural and magnetic properties of cubic perovskites, PrCoO₃ and NdCoO₃, are studied using the full potential linearized augmented plane wave (FP-LAPW) method within the frame work of density functional theory (DFT). The structural parameters are also investigated by analytical techniques. The calculated structural parameters are consistent with the experimental results. The strong hybridization of the O-2p, Co-3d and Pr/Nd-4 f states around the Fermi level reveals that these compounds are metallic. It is also found that the origin of ferromagnetism in these compounds is double-exchange interaction between Co-3d states via O-2p states (Co-O-Co).     

An unusual bioactive oleanane triterpenoid from Rhododendron campanulatum D.Don

An unusual oleanane triterpene(1) was isolated from aerial parts of Rhododendron campanulatum.The compound had shown prominent antibacterial and immunomodulatory activities.The structure of the compound was determined by spectroscopic data including 1D and 2D NMR spectral analysis.