The antioxidative effect of heat-shock protein 70 in dendritic cells.

Reactive oxygen species (ROS) are produced by dendritic cells (DCs) during antigen presentation in contact hypersensitivity (CHS). ROS cause a number of non-enzymatic protein modifications, such as carbonylation. Carbonylated proteins in DCs in response to hapten have not been fully identified yet. To identify the proteins carbonylated by ROS, murine epidermis-derived DC line XS106 was challenged with a hapten, 2,4,6-trinitrobenzene sulphonic acid (TNBS). MALDI-TOF analysis revealed that heat-shock protein 70 (HSP70) was one of the carbonylated proteins induced by TNBS. To verify the role of HSP70 in TNBS-treated XS106 cell, we fused protein transduction domain (PTD) with HSP70 to facilitate protein delivery into the cell. The transfected fusion protein HSP70 within the cell caused transient increase of the cellular level of HSP70. Transient increase of HSP70 level in XS-106 DCs resulted in inhibition of ROS production, carbonylation of HSP70, p38 MAPK activation and subsequently IL-12 secretion. To investigate the effects of PTD-HSP70 in vivo, ear-swelling experiments with 2,4,6-trinitro-1-chlorobenzene (TNCB) were performed in BALB/c mice. Pretreatment of PTD-HSP70 reduced the CHS response to TNCB in vivo. We report here that carbonylation of HSP70 by ROS is associated with the pathogenesis of CHS, suggesting possibility of HSP70-targeting therapy in CHS.

Relating skin sensitizing potency to chemical reactivity: reactive Michael acceptors inhibit NF-κB signaling and are less sensitizing than S(N)Ar- and S(N)2- reactive chemicals.

The skin sensitization potency of chemicals is partly related to their reactivity to proteins. This can be quantified as the rate constant of the reaction with a model peptide, and a kinetic profiling approach to determine rate constants was previously proposed. A linear relationship between the skin sensitization potency in the local lymph node assay (LLNA) and the rate constant for Michael acceptors was reported, characterized by a relatively flat regression line. Thus, a 10-fold increase of reactivity correlates to an increase of the sensitization potential of only 1.7-fold. Here, we first validate this model by repeating previous data and testing additional Michael acceptors and prove that the model is both reproducible and robust to the addition of new data. Chemicals of different mechanistic applicability domains, namely, S(N)Ar- and S(N)2-reactive sensitizers, were then tested with the same kinetic profiling approach. A linear relationship between sensitization potency in the LLNA and rate constants was also found, yet with a much steeper slope, i.e., for S(N)Ar- and S(N)2-reactive sensitizers, increasing reactivity correlates to a much stronger increase in sensitization potency. On the basis of the well-known inhibitory activity of some Michael acceptors on IKK kinase, it was hypothesized that the difference in the slopes is due to the specific anti-inflammatory potential of Michael acceptor chemicals. Therefore, all chemicals were tested for anti-inflammatory activity in a reporter gene assay for the inhibition of NF-κB activation. Increasingly reactive Michael acceptors have increasing anti-inflammatory potential in this assay, whereas no such biological activity was detected for the S(N)Ar and S(N)2 reactive sensitizers. Thus, the increasing reactivity of Michael acceptors confers both anti-inflammatory and skin sensitizing/pro-inflammatory potential, which may partially neutralize each other. This may be the reason for the relatively weak relationship between the potency in the LLNA and the rate constant of this particular group of chemicals.

Synthesis, characterization and evaluation of 1,2-bis(2,4,6-trinitrophenyl) hydrazine: a key precursor for the synthesis of high performance energetic materials.

1,2-Bis(2,4,6-trinitrophenyl) hydrazine (3) is one of the precursors in the synthesis of an important energetic material viz., hexanitrazobenzene. The simple and convenient lab scale synthesis of title compound (3) was carried out by the condensation of picryl chloride (2) with hydrazine hydrate at 30-50 degrees C in methanol based on the lines of scanty literature reports. Picryl chloride was synthesized by the reaction of picric acid (1) with phosphorous oxychloride based on the lines of reported method. The synthesized compound (3) was characterized by IR and 1H NMR spectral data. Some of the energetic properties of the synthesized compound have also been studied. The theoretically computed energetic properties of the title compound (3) indicated the superior performance in comparison to tetranitrodibenzo tetraazapentalene (TACOT) and hexanitrostilbene (HNS) in terms of velocity of detonation.

Synthesis and spectroscopic studies of the charge transfer complexes of 2- and 3-aminopyridine.

The interactions of the electron donors 2-aminopyridine (2APY) and 3-aminopyridine (3APY) with the pi-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2-chloro-1,3,5-trinitrobenzene (picryl chloride, PC), and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge transfer (CT) complexes were recorded. Photometric titration showed that the stoichiometries of the reactions were fixed and depended on the nature of both the donor and the acceptor. The molecular structures of the CT-complexes were, however, independent of the position of the amino group on the pyridine ring and were formulated as [(APY)(TCNE)], [(APY)(DDQ)], [(APY)(PC)], and [(APY) (chloranil)]. The formation constants (K(CT)), charge transfer energy (E(CT)) and molar extinction coefficients (epsilon(CT)) of the formed CT-complexes were obtained.

Novel potent and selective calcium-release-activated calcium (CRAC) channel inhibitors. Part 2: Synthesis and inhibitory activity of aryl-3-trifluoromethylpyrazoles.

To identify potent and selective calcium-release-activated calcium (CRAC) channel inhibitors, we examined the structure-activity relationships of the pyrazole and thiophene moieties in compound 4. Compound 25b was found to exhibit highly potent and selective inhibitory activity for CRAC channels and further modifications of the pyrazole and benzoyl moieties of compound 25b produced compound 29. These compounds were potent inhibitors of IL-2 production in vitro and also acted as inhibitors in pharmacological models of diseases resulting from T-lymphocyte activation, after oral administration.