Different effects of two cyclic chalcone analogues on redox status of Jurkat T cells

Chalcones are intermediary compounds of the biosynthetic pathway of the naturally flavonoids. Previous studies have demonstrated that chalcones and their conformationally rigid cyclic analogues have tumour cell cytotoxic and chemopreventive effects. It has been shown that equitoxic doses of the two cyclic chalcone analogues (E)-2-(4′-methoxybenzylidene)-(2) and (E)-2-(4′-methylbenzylidene)-1-benzosuberone (3) have different effect on cell cycle progress of the investigated Jurkat cells. It was also found that the compounds affect the cellular thiol status of the treated cells and show intrinsic (non-enzyme-catalyzed) reactivity towards GSH under cell-free conditions. In order to gain new insights into the cytotoxic mechanism of the compounds, effects on the redox status and glutathione level of Jurkat cells were investigated. Detection of intracellular ROS level in Jurkat cells exposed to 2 and 3 was performed using the dichlorofluorescein-assay. Compound 2 did not influence ROS activity either on 1 or 4 h exposure; in contrast, chalcone 3 showed to reduce ROS level at both timepoints. The two compounds had different effects on cellular glutathione status as well. Compound 2 significantly increased the oxidized glutathione (GSSG) level showing an interference with the cellular antioxidant defence. On the contrary, chalcone 3 enhanced the reduced glutathione level, indicating enhanced cellular antioxidant activity. To investigate the chalcone–GSH conjugation reactions under cellular conditions, a combination of a RP-HPLC method with electrospray ionization mass spectrometry (ESI-MS) was performed. Chalcone–GSH adducts could not be observed either in the cell supernatant or the cell sediment after deproteinization. The investigations provide further details of dual – cytotoxic and chemopreventive – effects of the cyclic chalcone analogues.     

Different effects of two cyclic chalcone analogues on redox status of Jurkat T cells

Chalcones are intermediary compounds of the biosynthetic pathway of the naturally flavonoids. Previous studies have demonstrated that chalcones and their conformationally rigid cyclic analogues have tumour cell cytotoxic and chemopreventive effects. It has been shown that equitoxic doses of the two cyclic chalcone analogues (E)-2-(4′-methoxybenzylidene)-(2) and (E)-2-(4′-methylbenzylidene)-1-benzosuberone (3) have different effect on cell cycle progress of the investigated Jurkat cells. It was also found that the compounds affect the cellular thiol status of the treated cells and show intrinsic (non-enzyme-catalyzed) reactivity towards GSH under cell-free conditions. In order to gain new insights into the cytotoxic mechanism of the compounds, effects on the redox status and glutathione level of Jurkat cells were investigated. Detection of intracellular ROS level in Jurkat cells exposed to 2 and 3 was performed using the dichlorofluorescein-assay. Compound 2 did not influence ROS activity either on 1 or 4 h exposure; in contrast, chalcone 3 showed to reduce ROS level at both timepoints. The two compounds had different effects on cellular glutathione status as well. Compound 2 significantly increased the oxidized glutathione (GSSG) level showing an interference with the cellular antioxidant defence. On the contrary, chalcone 3 enhanced the reduced glutathione level, indicating enhanced cellular antioxidant activity. To investigate the chalcone–GSH conjugation reactions under cellular conditions, a combination of a RP-HPLC method with electrospray ionization mass spectrometry (ESI-MS) was performed. Chalcone–GSH adducts could not be observed either in the cell supernatant or the cell sediment after deproteinization. The investigations provide further details of dual – cytotoxic and chemopreventive – effects of the cyclic chalcone analogues.     

Comparative evaluation of two dye probes in the rat everted gut sac model for unambiguous classification of P-gp substrate and inhibitor

IntroductionP-glycoprotein (P-gp) plays a crucial role in beta-amyloid efflux from the blood–brain barrier thus becoming a promising pharmacological target in the treatment of Alzheimer's disease (AD). The increase of P-glycoprotein expression and activity by a P-gp inducer could be an effective pharmacological strategy in slowing or halting the progression of AD. Commonly used in vitro methods to classify a P-gp interacting molecule as substrate, inhibitor, modulator or inducer are not always confirmed by in vivo experiments. Here we validate the new dye-probe beta-amyloid (1–40) HiLyte Fluor? TR-labeled (Ab-HiLyte) (Anaspec) P-gp mediated transport in the ex vivo rat everted gut sac assay by using MC18 or MC266, a fully characterized P-gp inhibitor and substrate, respectively, and compare it with the commonly used dye rhodamine.MethodsMale Wistar rats' everted intestines were divided into sacs, each sac was filled with 10 μM Ab-HiLyte with or without 50 μM of MC18 or MC266. Ab-HiLyte concentrations in mucosal fluid were measured spectrophotometrically at 594 nm at each appropriate time.ResultsThe Ab-HiLyte P-gp mediated efflux had a K = 1.00 × 10^? 2 min^? 1 and t_1/2 = 68.74 min, while in the presence of MC18, the Ab-HiLyte efflux turned out to be reduced by an order of magnitude (K = 1.65 × 10^? 3 min^? 1) and the half life is extremely increased (t_1/2 = 419 min). A P-gp substrate, like MC266, determines no change in the efflux of Ab: the kinetic constant and the half life turned out to be unmodified (K = 1.81 × 10^? 2 min^? 1 and t_1/2 = 38.28 min).DiscussionThe results demonstrate that the new dye probe, Ab-HiLyte, could be a probe of choice to unequivocally distinguish between a P-gp substrate and an inhibitor. This is particularly important as different groups obtain a controversial classification of the same compound.     

Effects of Zizyphus lotus L. (Desf.) polyphenols on Jurkat cell signaling and proliferation

We assessed the effects of Zizyphus lotus L. (Desf.) polyphenols (ZLP) on T-cell signaling and proliferation. Our results showed that ZLP exerted no effect on the increases in intracellular free calcium concentrations, [Ca^2 +]_i, in human Jurkat T-cells. However, ZLP modulated the thapsigargin-induced increases in [Ca^2 +]_i in these cells. ZLP treatment was found to decrease the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). In addition, ZLP induced a rapid (t_1/2 = 33 s) and dose-dependent decrease in intracellular pH (pH_i) in human Jurkat T-cells. Furthermore, ZLP significantly curtailed T-cell proliferation by diminishing their progression from S to G2/M phase of cell cycle, and the expression of interleukin-2 (IL-2) mRNA. Taken together, the results of the present study demonstrate that ZLP modulate cell signaling and exert immunosuppressive effects in human T-cells.     

Isothiazole dioxide derivative 6n inhibits vascular smooth muscle cell proliferation and protein farnesylation

Isothiazole dioxides have been shown to inhibit Trypanosoma brucei protein farnesyltransferase (PFTase) in isolated enzyme, but elicited only a minor effect on mammalian PFTase. In the present study we have evaluated the effect of 3-diethylamino-4-(4-methoxyphenyl)-isothiazole 1,1-dioxides with different substituents at C5, on rat PFTase and protein geranylgeranyltransferase-I (PGGTase-I) with the final aims to improve the potency against mammalian PFTase and to identify new compounds with antiproliferative properties. For these purposes, in vitro and cell culture models have been utilized. The results showed that isothiazole dioxides with C4–C5 double bond and sulfaryl substituted at the C5 position but none of the dihydro-derivatives, were able to inhibit in vitro PFTase in a concentration dependent manner (IC₅₀ ranging from 8.56 to 1015 μM). Among those, compound 6n (C5; methyl-S) displayed 500-fold higher inhibitory potency on PFTase than PGGTase-I. Compound 6n was shown to affect rat smooth muscle cell (SMC) proliferation at concentrations similar (IC₅₀ = 61.4 μM) to those required to inhibit [³H]-farnesol incorporation into cellular proteins (−44.1% at 100 μM). Finally, compound 6n interferes with rat SMC proliferation by blocking the progression of G0/G1 phase without inducing apoptosis, as assessed by [³H]-thymidine incorporation assay and flow cytometry analysis. Taken together, we described a new PFTase inhibitor containing the isothiazole dioxide moiety that affects mammalian protein farnesylation and SMC proliferation by inhibiting G0/G1 phase of the cell cycle.     

Chemical composition,antiproliferative and antioxidant properties of lipid classes in ordinary and dark muscles from chub mackerel (Scomber japonicus)

This study investigated to compare lipid profiles in ordinary and dark muscles from chub mackerel and to examine antiproliferative and antioxidative properties of lipid classes. The average levels of neutral lipids (NL), glycolipids (GL), and phospholipids (PL) in ordinary muscle were 92.32 ± 0.19%, 5.10 ± 0.48%, and 2.58 ± 0.46%; in dark muscle were 96.88 ± 0.15%, 2.59 ± 0.36%, and 0.54 ± 0.29%, respectively. The fatty acid composition indicated that PL had a higher percentage of PUFA (especially 22:6n?3) with lower percentages of SFA and MUFA compared to NL and GL (p < 0.05). The main ion peaks of GL in ordinary and dark muscles showed that monocharged and bischarged molecular ion were presented at m/z 876.9 and 438.8, respectively. In MTT assay, inhibition of AGS and HT-29 cell proliferation was greatest with the 0.5 and 1.0 mg mL^?1 GL treatments. The GL of ordinary muscle with 0.05 mg mL^?1 concentrations markedly decreased the levels of reactive oxygen species (ROS) induced by H₂O₂ compared to the control (p < 0.05). From our results, GL might have antiproliferative and antioxidant properties based on protective effect against the production of intracellular ROS.     

Cytotoxic effect of inositol hexaphosphate and its Ni(II) complex on human acute leukemia Jurkat T cells

Inositol hexaphosphate (InsP₆) is present in cereals, legumes, nuts and seed oils and is biologically active against some tumor and cancer cells. Herein, this study aimed at evaluating the cellular toxicity, antiproliferative activity and effects on cell cycle progression of free InsP₆ and InsP₆–Ni(II) of leukemic T (Jurkat) and normal human cells. Treatments with InsP₆ at concentrations between 1.0 and 4.0 mM significantly decreased the viability of Jurkat cells, but showed no cytotoxic effect on normal human lymphocytes. Treatment with InsP₆–Ni(II) complex at concentrations between 0.05 and 0.30 mM showed an anti-proliferative dose and a time-dependent effect, with significantly reduced cell viability of Jurkat cells but showed no cytotoxic effect on normal human lymphocytes as compared to the control. Ni(II) free ion was toxic to normal cells while InsP₆–Ni(II) had no cytotoxic effect. The InsP₆–Ni(II) complex potentiated (up to 10 ×) the antiproliferative effect of free InsP₆ on Jurkat cells. The cytometric flow assay showed that InsP₆ led to an accumulation of cells in the G0/G1 phase of the cell cycle, accompanied by a decrease in the number of cells in S and G2/M phases, whereas InsP₆–Ni(II) has led to an accumulation of cells in the S and G2/M phases. Our findings showed that InsP₆–Ni(II) potentiates cytotoxic effects of InsP₆ on Jurkat cells and may be a potential adjuvant in the treatment of cancer.     

Synthetic polysulfane derivatives induce cell cycle arrest and apoptotic cell death in human hematopoietic cancer cells

Natural polysulfanes including diallyltrisulfide (DATS) and diallyltetrasulfide (DATTS) from garlic possess antimicrobial, chemopreventive and anticancer properties. However these compounds exhibit chemical instability and reduced solubility, which prevents their potential clinical applicability. We synthesized six DATS and DATTS derivatives, based on the polysulfane motif, expected to exhibit improved physical and chemical properties and verified their biological activity on human leukemia cells.We identified four novel cytotoxic compounds (IC₅₀ values: compound 1, 24.96 ± 12.37 μM; compound 2, 22.82 ± 4.20 μM; compound 3, 3.86 ± 1.64 μM and compound 5, 40.62 ± 10.07 μM, compared to DATTS: IC₅₀: 9.33 ± 3.86 μM). These polysulfanes possess excellent differential toxicity, as they did not affect proliferating mononuclear blood cells from healthy donors.We further demonstrated ability of active compounds to induce apoptosis in leukemia cells by analysis of nuclear fragmentation and of cleavage of effector and executioner caspases. Apoptosis was preceded by accumulation of cells in G2/M phase with a pro-metaphase-like nuclear pattern as well as microtubular alterations. Prolonged and persistent arrest of cancer cells in early mitosis by the benzyl derivative identifies this compound as the most stable and effective one for further mechanistic and in vivo studies.     

Cytotoxicity and genotoxicity of phenazine in two human cell lines

Phenazine was recently identified as a drinking water disinfection byproduct (DBP), but little is known of its toxic effects. We examined in vitro cytotoxicity and genotoxicity of phenazine (1.9–123 μM) in HepG2 and T24 cell lines. Cytotoxicity was determined by an impedance-based real-time cell analysis instrument. The BrdU (5-bromo-2′-deoxyuridine) proliferation and MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assays were used to examine mechanisms of cytotoxicity. Genotoxicity was determined using the alkaline comet assay. Concentration-dependent cytotoxicity was observed in HepG2 cells, primarily due to an antiproliferative effect (BrdU 24 h IC₅₀: 11 μM; 48 h IC₅₀: 7.8 μM) observed as low as 1.9 μM. T24 cells experienced a minor antiproliferative effect (BrdU 24 h IC₅₀: 47 μM; 48 h IC₅₀: 17 μM). IC₅₀ values for HepG2 proliferation and viability were 54–77% lower compared to T24 cells. In both cell lines, IC₅₀ values for proliferation were 66–90% lower than those for viability. At phenazine concentrations producing equivalent cytotoxicity, HepG2 cells (1.9–30.8 μM) experienced no significant genotoxic effects, while T24 cells (7.7–123 μM) experienced significant genotoxicity at ⩾61.5 μM. While these effects were seen at phenazine concentrations above those found in disinfected water, the persistence of the antiproliferative effect and the differential toxicity in each cell line deserves further study.     

Chalcone derivatives from the fern Cyclosorus parasiticus and their anti-proliferative activity

Three new chalcone derivatives, named parasiticins A–C (1–3), were isolated from the leaves of Cyclosorus parasiticus, together with four known chalcones, 5,7-dihydroxy-4-phenyl-8-(3-phenyl-trans-acryloyl)-3,4-dihydro-1-benzopyran-2-one (4), 2′-hydroxy-4′,6′-dimethoxychalcone (5), 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (6), 2′,4′-dihydroxy-6′-methoxy-3′-methylchalcone (7). The chemical structures of the new isolated compounds were elucidated unambiguously by spectroscopic data analysis. The cytotoxic activities of compounds 1–7 were evaluated against six human cancer cell lines in vitro. Compounds 3 and 6 exhibited substantial cytotoxicity against all six cell lines, especially toward HepG2 with the IC₅₀ values of 1.60 and 2.82 μM, respectively. Furthermore, we demonstrated that compounds 3 and 6 could induce apoptosis in the HepG2 cell line, which may contribute significantly to their cytotoxicity.     

Study on the interaction between typical phthalic acid esters (PAEs) and human haemoglobin (hHb) by molecular docking

This work has evaluated the binding force between hHb and typcial PAEs (DMP, DEP, DPRP, DBP, DIBP, DHP and DPHP) using molecule docking technique. The DPHP with 3 aromatic rings has the strongest binding (-ΔG_binding: 6.0 kcal mol⁻¹) than other PAEs (-ΔG_binding: 2.91 ∼ 4.48 kcal mol⁻¹). The DMP with the lowest molecular weight has a high binding force (-ΔG_binding: 4.48 kcal mol⁻¹), while the DHP with the highest molecular weight has the lowest binding force (-ΔG_binding: 2.91 kcal mol⁻¹). When the length of side chain increases, the binding force trend to decrease, regarding the VDW forces and H-bonding. The lgK_ow-ΔG_binding plotting figure shows that a higher K_ow value is accompanied by a lower binding force. The aromatic ring existed in PAEs largely increases the binding force between the hHb and the PAEs. On the other hand, the PAEs with higher number of carbon, meaning a higher hydrophobicity, can enter into the hydrophobic space of hHb centre deeper and bond to different position. The aromatic ring decreases the depth of binding position in the hydrophobic space. This work provides basic data and a theoretical method to assess the transport and accumulation of PAEs in human body, and the cytotoxicity of PAEs to hBRCs.     

The effects of sulfur mustard exposure and freezing on transdermal penetration of tritiated water through ex vivo pig skin

The percutaneous absorption of tritiated water (³H₂O) through sulfur mustard (SM) exposed abdominal pig skin was measured using in vitro Franz-type static diffusion cells. The barrier function to water permeation following exposure to liquid SM for 8 min and excision 3 h later did not change significantly. A small, but statistically significant difference (P < 0.05) in steady state penetration (Jss), permeability coefficient (Kp) and lag time (t_L) of ³H₂O was observed between fresh skin and skin stored frozen (?20 °C) for up to two weeks. Steady-state penetration and Kp values were significantly higher (P < 0.05) in skin stored frozen compared with fresh skin. Fresh naïve skin had an average Kp of 1.65 × 10^?3 cm h^?1, whereas frozen naïve skin was 2.04 × 10^?3 cm h^?1. Fresh SM exposed skin had a mean Kp of 1.72 × 10^?3 cm h^?1, whereas frozen SM exposed skin was 2.31 × 10^?3 cm h^?1. Lag times were also shorter (P < 0.05) in skin that had been stored frozen. Frozen, SM-exposed porcine abdominal skin may be used for in vitro penetration studies, but effects of treatment and storage on the barrier layer should be taken into account.     

Oxidative stress contributes to silica nanoparticle-induced cytotoxicity in human embryonic kidney cells

In order to elucidate the nanoparticle-induced cytotoxicity and its mechanism, the effects of 20 and 50 nm silica nanoparticles on cultured human embryonic kidney (HEK293) cells were investigated. Cell viability, mitochondrial function, cell morphology, reactive oxygen species (ROS), glutathione (GSH), thiobarbituric acid reactive substance (TBARS), cell cycle and apoptosis were assessed under control and silica exposed conditions. Exposure to 20 or 50 nm SiO₂ nanoparticles at dosage levels between 20 and 100 μg/ml decreased cell viability in a dose-dependent manner. Median lethal dose (LD₅₀) of 24 h exposure was 80.2 ± 6.4 and 140.3 ± 8.6 μg/ml for 20 and 50 nm SiO₂ nanoparticles, respectively. Morphological examination revealed cell shrinkage and nuclear condensation after SiO₂ nanoparticle exposure. Increase in intracellular ROS level and reduction in GSH content were also observed in SiO₂ nanoparticle-exposed HEK293 cells. Increase in the amount of TBARS suggested an elevated level of lipid peroxidation. Flow cytometric analysis showed that SiO₂ nanoparticles can cause G2/M phase arrest and apoptotic sub-G1 population increase in a dose-dependent manner. In summary, exposure to SiO₂ nanoparticles resulted in a dose-dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.     

Cytotoxicity of flavones and flavonols to a human esophageal squamous cell carcinoma cell line (KYSE-510) by induction of G2/M arrest and apoptosis

In this study, cytotoxic effects of structurally related flavones and flavonols on a human esophageal squamous cell carcinoma cell line (KYSE-510) were determined, and the molecular mechanisms responsible for their cytotoxic effects were studied. The results of MTT assay showed that flavones (luteolin, apigenin, chrysin) and flavonols (quercetin, kaempferol, myricetin) were able to induce cytotoxicity in KYSE-510 cells in a dose- and time-dependent manner, and the cytotoxic potency of these compounds was in the order of: luteolin > quercetin > chrysin > kaempferol > apigenin > myricetin. Flow cytometry and DNA fragmentation analysis indicated that the cytotoxicity induced by flavones and flavonols was mediated by G₂/M cell cycle arrest and apoptosis. Furthermore, the expression of genes related to cell cycle arrest and apoptosis was assessed by oligonucleotide microarray, real-time RT-PCR and Western blot. It was shown that the treatment of KYSE-510 cells with these compounds caused G₂/M arrest through up-regulation of p21^waf1 and down-regulation of cyclin B1 at the mRNA and protein levels, and induced p53-independent mitochondrial-mediated apoptosis through up-regulation of PIG3 and cleavage of caspase-9 and caspase-3. The results of western blot analysis further showed that increases of p63 and p73 protein translation or stability might be contributed to the regulation of p21^waf1, cyclin B1 and PIG3.     

Antitumor effects of a selenium heteropoly complex in K562 cells

The aim of this study was to investigate the anti-tumor effects and mechanism of the selenium heteropoly compound (C₂H₁₀N₂)₅ (NH₄)₄H₂[Se₂W₁₀V₈O₆₂]·9H₂O (SeWV) in K562 cells. The results showed that 0.32–10.15 × 10^–3 mmol/L SeWV could significantly inhibit the proliferation of K562 cells in vitro, as determined by the MTT assay, with IC₅₀ values of 3.07 and 2.69 × 10^–3 mmol/L after 48 and 72 h of treatment with SeWV, respectively. Studies of the cell cycle indicated that SeWV could induce K562 cells gathered in the G₂/M phase upon treatment for 24 and 48 h, and a significant sub-G1 peak was evident at 0.32 and 2.54 × 10^–3 mmol/L after treatment for 24 h. Morphological observations revealed typical apoptotic features. SeWVcaused the accumulation of Ca²⁺, Mg²⁺ and ROS, and the reduction of pH and mitochondrial membrane potential (MMP) in K562 cells as evidenced by confocal laser scanning microscopy. Experiments also showed that the expression of Bcl-2 was significantly inhibited, but Bax was increased by SeWV at 5.07 × 10^–3 mmol/L. Additionally, the content of cytochrome-C was increased after treatment for 24 h. The experiment implied that SeWV had anti-tumor activity and that its mechanism was partially attributable to the induction of cell cycle distribution and apoptosis that was induced by a change in intracellular ion homeostasis.     

Induction of G2/M arrest,caspase activation and apoptosis by α-santonin derivatives in HL-60 cells

Sesquiterpene lactones (SLs) are natural products with a variety of biological activities. Previously, we demonstrated the cytotoxic effects of three new α-santonin derivatives on different tumor cell lines with low toxic effects upon peripheral human leukocytes. Here, we evaluated the mechanism of action triggered by these derivatives. HL-60 cell cycle determined after 24 h treatment revealed a significant inhibition on cell-cycle progression and leading to an increasing of cells in G₂/M [7.6% and 9.0% for compound 3% and 9.0% and 8.6% for compound 4 (1 and 2 μM, respectively)]. However, after 48 h exposure, all compounds caused G₂/M reduction and a significant DNA fragmentation. Compounds 2, 3 and 4 were able to induce apoptosis on leukemia cells, which was corroborated by phosphatidyserine externalization and activation of caspases-3 and -7 after 24 h exposure. None of the derivatives analyzed caused depolarization of mitochondrial membrane within 24 h of incubation, suggesting the involvement of the extrinsic apoptotic pathway in the death process. The antiproliferative action of these compounds is related to the DNA synthesis inhibition and cell cycle arrest, which probably lead to apoptosis activation. Therefore, these santonin derivatives are promising lead candidates for development of new cytotoxic agents.     

Kynurenic acid inhibits proliferation and migration of human glioblastoma T98G cells

BackgroundKynurenic acid (KYNA), tryptophan metabolite synthesized in the kynurenine pathway, is an endogenous antagonist of α-7 nicotinic receptor and all ionotropic glutamate receptors: N-methyl-d-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxasole propionate (AMPA) receptor and kainate receptor. The antiproliferative activity of KYNA toward colon and renal cancer cells has recently been discovered. The aim of the study was to verify whether human Glioblastoma tumors contain KYNA and if KYNA influences glioma cell proliferation and migration.MethodsKYNA content in Glioblastoma tumor samples was determined using HPLC. Proliferation of human glioblastoma T98G cells was measured by means of MTT and BrdU assays. Wound assay was used to evaluate the effect of KYNA on cancer cell migration.ResultsKYNA was detected in all tested Glioblastoma tumor samples (100.3 ± 17.6 pmol/g wet weight). In a series of experiments the antiproliferative activity of KYNA against T98G cells was revealed (IC₅₀ = 1.3 mM). Moreover, KYNA reversed the stimulatory effect of glutamate on glioma cell proliferation and enhanced antiproliferative effect of glutamate receptor antagonists MK801 and GYKI 52466. Next, KYNA at concentrations much lower than those needed to reduce cell proliferation elicited a prominent inhibitory effect on glioma cell motility. Moreover, co-incubation of temozolomide, a drug commonly used in antiglioblastoma therapy, with KYNA gave a superior effect than each of the substances applied alone.ConclusionsWe demonstrate the antiproliferative and antimigrative potential of KYNA against glioma cells in vitro.     

Human Skin is Permselective for the Small,Monovalent Cations Sodium and Potassium but not for Nickel and Chromium

The molar conductance of excised human skin (Λ_skin) immersed in electrolyte solutions comprising four cationic (Na⁺, K⁺, Ni^2 +, and Cr^3 +) and five anionic (Cl^?, NO₃^?, SO₄^2 ?, CrO₄^2 ?, and Cr₂O₇^2 ?) species was determined as a function of concentration in Franz diffusion cells. Cation transport numbers for four of these electrolytes were measured in Franz cells by the electromotive force method. Parallel experiments were conducted in solutions alone to establish the validity of the technique. Molar conductance decreased with increasing concentration, following the Kohlrausch law, over a 4–12-fold concentration range. Molar conductance and cation transport values at infinite dilution were extrapolated from these data and used to estimate ionic conductances at infinite dilution. These values were subsequently used to calculate limiting ion mobilities and diffusivities in solution and skin. Results for skin showed the expected increase in cation permselectivity for monovalent cations and a 40–110-fold reduction in effective diffusivities with respect to those in solution. However, Ni^2 + and Cr^3 + were relatively less mobile in skin than in solution. Salt diffusivities calculated from ionic mobilities in skin provided a partial explanation for the difference in allergenic potency of NiCl₂compared with NiSO₄ and Cr^3 + versus Cr^6 + salts.     

Anti-allergic activity of emodin on IgE-mediated activation in RBL-2H3 cells

BackgroundEmodin (1,3,8-trihydroxy-6-methylanthraquinone) is a Chinese herbal anthraquinone derivative from the rhizome of rhubarb (Rheum palmatum L.) that exhibits numerous biological activities, such as antitumor, antibacterial, antiinflammatory, and immunosuppressive. In the present studies, the anti-allergic activities of emodin were investigated to elucidate the underlying active mechanisms.MethodsThe inhibitory effects of emodin on the IgE-mediated allergic response in rat basophilic leukemia (RBL-2H3) cells were evaluated by measuring the release of granules and cytokines. The Ca²⁺ mobilization in RBL-2H3 cells loaded with the Ca²⁺-reactive fluorescent probe Fluo-4 AM was also measured by laser scanning confocal microscope.ResultsEmodin inhibited the release of β-hexosaminidase (β-HEX; IC₅₀ = 5.5 μM) and tumor necrosis factor (TNF)-α (IC₅₀ = 11.5 μM) from RBL-2H3 cells induced by 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) and displayed stronger inhibition of β-HEX release than ketotifen fumarate salt (IC₅₀ = 63.8 μM). Emodin at a concentration of 12.5 μM also inhibited the DNP-BSA-induced influx of extracellular Ca²⁺ in RBL-2H3 cells.ConclusionsThese results suggested that emodin likely exhibits anti-allergic activities via increasing the stability of the cell membrane and inhibiting extracellular Ca²⁺ influx.     

Potent inhibition of human neutrophil activations by bractelactone,a novel chalcone from Fissistigma bracteolatum

Fissistigma bracteolatum is widely used in traditional medicine to treat inflammatory diseases. However, its active components and mechanisms of action remain unclear. In this study, (3Z)-6,7-dihydroxy-4-methoxy-3-(phenylmethylidene)-5-(3-phenylpropanoyl)-1-benzofuran-2(3H) (bractelactone), a novel chalcone from F. bracteolatum, showed potent inhibitory effects against superoxide anion (O₂^?) production, elastase release, and CD11b expression in formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP)-induced human neutrophils. However, bractelactone showed only weak inhibition of phorbol myristate acetate-caused O₂^? production. The peak cytosolic calcium concentration ([Ca^2 +]_i) was unaltered by bractelactone in FMLP-induced neutrophils, but the decay time of [Ca^2 +]_i was significantly shortened. In a calcium-free solution, changes in [Ca^2 +]_i caused by the addition of extracellular Ca^2 + were inhibited by bractelactone in FMLP-activated cells. In addition, bractelactone did not alter the phosphorylation of p38 MAPK, ERK, JNK, or AKT or the concentration of cAMP. These results suggest that bractelactone selectively inhibits store-operated calcium entry (SOCE). In agreement with this concept, bractelactone suppressed sustained [Ca^2 +]_i changes in thapsigargin-activated neutrophils. Furthermore, bractelactone did not alter FMLP-induced formation of inositol 1,4,5-triphosphate. Taken together, our results demonstrate that the anti-inflammatory effects of bractelactone, an active ingredient of F. bracteolatum, in human neutrophils are through the selective inhibition of SOCE.