Subunit-specific effects of poricoic acid A on NMDA receptors.

BACKGROUND: N-methyl-D-aspartate (NMDA) receptor is a tetrameric protein complex composed of glycine-linked NR1 subunits and glutamate-linked NR2 subunits. There are four NR2 subunits (A-D) that differ in development, anatomy, and function profiles. They play various roles in normal and neuropathologic conditions. Specific agonists, antagonists, and modulators of subunits for selective NMDA receptors may be precious mediational tools and potent agents for treating diseases. The objective of this study was to determine the effect of poricoic acid A on NMDA receptor known to mediate excitatory synaptic transmission factors and cause changes in synaptic strength. Inhibitory effect of poricoic acid A on NR1a combined with NR2A, NR2B, NR2C, or NR2D receptor was evaluated. METHODS: Glutamate-mediated currents for each NR1a and NR2 subunits were investigated using two-electrode voltage-clamp techniques. Molecular modeling and molecular dynamics simulation studies were carried out with Autodock Tools. Poricoic acid A and NMDA receptor protein complex were examined with Ligplot and Pymol docking program. Ligplot shows binding activity at the protein and the ligand. RESULTS: The inhibitory effect of poricoic acid A on glutamate-induced inward current in a concentration-dependent manner that was reversible. Half inhibitory concentrations of glutamate on NR1a/NR2A, NR1a/NR2B, NR1a/NR2C, and NR1a/NR2D receptors were 9.6 ± 1.2, 5.7 ± 0.4, 46.1 ± 21.5, and 21.5 ± 8.2 µM, respectively. This corresponded to the order of inhibitory effect of oocyte expressing NR1a and NR2s subunit of NR1a/NR2B > NR1a/NR2A > NR1a/NR2C > NR1a/NR2D. CONCLUSIONS: Taken together, these results indicate that poricoic acid A can modulate the expression of NMDA receptor. In addition, the regulation of excitatory ligand-gating ion channel by poricoic acid A may have pharmaceutical functions on excitatory synaptic transmission of neuronal system.

Effectiveness of Modal Decomposition for Tapping Atomic Force Microscopy Microcantilevers in Liquid Environment.

The modal decomposition of tapping mode atomic force microscopy microcantilevers in liquid environments was studied experimentally. Microcantilevers with different lengths and stiffnesses and two sample surfaces with different elastic moduli were used in the experiment. The response modes of the microcantilevers were extracted as proper orthogonal modes through proper orthogonal decomposition. Smooth orthogonal decomposition was used to estimate the resonance frequency directly. The effects of the tapping setpoint and the elastic modulus of the sample under test were examined in terms of their multi-mode responses with proper orthogonal modes, proper orthogonal values, smooth orthogonal modes and smooth orthogonal values. Regardless of the stiffness of the microcantilever under test, the first mode was dominant in tapping mode atomic force microscopy under normal operating conditions. However, at lower tapping setpoints, the flexible microcantilever showed modal distortion and noise near the tip when tapping on a hard sample. The stiff microcantilever had a higher mode effect on a soft sample at lower tapping setpoints. Modal decomposition for tapping mode atomic force microscopy can thus be used to estimate the characteristics of samples in liquid environments.

Methallyl isothiocyanate inhibits the caspase-1 activity through the inhibition of intracellular calcium levels.

Isothiocyanates (ITCs) play a major role in the potential chemopreventive effect. Cruciferous vegetables are a particularly abundant source of ITCs. Methallyl ITC (MAITC) belongs to ITCs as a synthesized compound. However, the effects of MATIC have never been elucidated. The aim of this work was to investigate the anti-inflammatory effects and mechanisms of methallyl isothiocyanate (MAITC) in mast cells. MAITC suppressed the intracellular calcium levels in phorbol myristate acetate (PMA) plus calcium ionophore A23187 (PMACI)-stimulated human mast cell line (HMC-1) cells. MAITC significantly inhibited the production and mRNA expression of interleukin (IL)-1ß in PMACI-stimulated HMC-1 cells. The activities of caspase-1 and receptor interacting protein-2 were significantly inhibited by the treatment with MAITC in PMACI-stimulated HMC-1 cells. The activation of nuclear factor-κB and phosphorylation of extracellular signal-regulated kinase and IκBα were inhibited by the treatment with MAITC. In addition, MAITC significantly inhibited the production and mRNA expression of IL-6 and tumor necrosis factor-α in PMACI-stimulated HMC-1 cells. Furthermore, MAITC significantly inhibited caspase-1 enzymatic activity and reactive oxygen species generation in PMA-stimulated HMC-1 cells. Taken together, we can conclude that MAITC showed an anti-inflammatory effect on mast cell-mediated inflammatory reaction.

Scrophularia buergeriana regulates cytokine production in vitro.

The Scrophularia buergeriana (SB) has long been used to treat various diseases an account of its antimicrobial and anti-virus activity. However, it is unclear how SB regulates the immune responses. This study investigated the effect of SB on the production of cytokines in a human T-cell line, MOLT-4 cells, and mouse peritoneal macrophages. The MOLT-4 cells were cultured for 24 h in the presence or absence of SB plus concanavalin (con) A. SB plus con A significantly increased the level of interleukin (IL)-2, IL-4 and interferon (IFN)-gamma production compared with that of con A alone (approximately 1.79-fold for IL-2, 2-fold for IL-4, and 1.85-fold for IFN-gamma, p < 0.05). SB plus recombinant IFN-gamma (rIFN-gamma) increased the level of IL-12 and NO production compared with rIFN-gamma alone. In addition, SB plus rIFN-gamma increased the level the iNOS expression on mouse peritoneal macrophages. Overall, SB may have an immune-enhancement effect through cytokine production.

Leonurus sibiricus induces nitric oxide and tumor necrosis factor-alpha in mouse peritoneal macrophages.

Using mouse peritoneal macrophages, we have examined the mechanism by which Leonurus sibiricus (LS) regulates nitric oxide (NO) production. When LS was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production; however, LS by itself had no effect on NO production. The increased production of NO from rIFN-gamma plus LS-stimulated cells was almost completely inhibited by pretreatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappaB. Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus LS caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effect of LS on TNF-alpha production significantly. Because NO and TNF-alpha play an important role in immune function and host defense, LS treatment could modulate several aspects of host defense mechanisms as a result of stimulation of the inducible nitric oxide synthase.

Horseradish peroxidase immobilized on poly(thiophene-2-aminophenol-3-thiopheneacetic acid) film electrode with Au nanoparticle-fabrication and evaluation as hydrogen peroxide sensor.

Enzyme immobilized electrode was fabricated by two methods. In one of the methods, gold-nanoparticles (Au-NPs) prepared by gamma-irradiation were loaded into the copolymer film and horseradish peroxidase (HRP) was immobilized into the Au-NPs loaded copolymer film through physical entrapment. In the other method, the Au-NPs was prepared by electrochemical reduction of Au ions on the surface of poly(Th-AP-TAA) and HRP was immobilized into the Au-NPs. The enzyme immobilized electrodes were tested for electrocatalytic activities towards sensing of H2O2.