Immunosuppressive properties of flavonoids isolated from Boerhaavia diffusa Linn.
ABSTRACT Plant extracts have been widely evaluated for possible immunomodulatory properties. We have earlier reported that ethanolic extract of Boerhaavia diffusa root, a plant used in Indian traditional medicine, has significant immunomodulatory potential. B. diffusa hexane, chloroform and ethanol extracts, and two pure compounds Bd-I (eupalitin-3-O-beta-D-galactopyranoside) and Bd-II (eupalitin) were evaluated in vitro for their effect on T cell mitogen (phytohemagglutinin; PHA) stimulated proliferation of human peripheral blood mononuclear cell (PBMC), mixed lymphocyte culture, lipopolysaccharide (LPS) stimulated nitric oxide production by RAW 264.7, PHA and LPS induced IL-2 and TNF-alpha production, in human PBMCs, superoxide production in neutrophils, human natural killer (NK) cell cytotoxicity and nuclear translocation of nuclear factor-(kappa)B and AP-1 in PHA stimulated PBMCs. The chloroform and ethanol extracts inhibited PHA stimulated proliferation of peripheral blood mononuclear cells, two-way MLR, NK cell cytotoxicity as well as LPS induced NO production by RAW 264.7; the hexane extract showed no activity. Bd-I purified from the ethanolic extract at equivalent dose, inhibited PHA-stimulated proliferation of peripheral blood mononuclear cells, two-way MLR and NK cell cytotoxicity as well as LPS induced NO production by RAW 264.7 equally or more effectively than the parent ethanolic extract. Bd-I inhibited production of PHA stimulated IL-2 at the protein and mRNA transcript levels and LPS stimulated TNF-alpha production in human PBMCs; it also blocked the activation of DNA binding of nuclear factor-(kappa)B and AP-1, two major transcription factors centrally involved in expression of the IL-2 and IL-2R gene, which are necessary for T cell activation and proliferation. Our results report selective immunosuppressive activity of B. diffusa leaf extracts and that this activity lies in eupalitin-3-O-beta-D-galactopyranoside (Bd-I) isolated and purified from the ethnaolic extract. Thus, Bd-I could be a candidate for development as an immunosuppressive agent.
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ABSTRACT: The Zn-Al eutectoid alloy (78Zn-22Al) has been studied in uniaxial tension at 520°F (271°C) and the results have been related to the thickness distributions in thermoformed parts. Contrary to published literature strain has been found to be an important variable. Depending on strain-rate and the temper of the sheet this alloy exhibits both strain hardening and softening.International Journal of Mechanical Sciences - INT J MECH SCI. 01/1971; 13(1):63-64.
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ABSTRACT: The superplastic forming of Al-4.5% Mg alloy sheet, using gas pressure at elevated temperatures, has been studied. By using suitable models of material behaviour and friction, it was possible to simulate this process with finite-element methods (FEM). A rigid-plastic model was used, with the assumption that the material behaved as a membrane, to model axisymmetric forms. Such simulations could then be used to optimise the process, in terms of minimising the forming time required whilst minimising the amount of cavitation damage or retaining acceptable material thickness. To apply the optimisation in practice, and for the generation of experimental data, a high degree of process control was required. Control of forming pressure is not sufficient for this purpose and volume-rate control was used. Good correlation was found between the predictions of the simulation and results from formed parts, and friction was found to be a very important factor in the process. It was possible to reduce the amount of cavitation significantly by applying an optimised volume-rate cycle.Journal of Materials Processing Technology - J MATER PROCESS TECHNOL. 01/1993; 38(3):589-612.