DSM-RX78, a new phosphodiesterase inhibitor, suppresses superoxide anion production in activated human neutrophils and attenuates hemorrhagic shock-induced lung injury in rats

Neutrophils are activated following hemorrhagic shock and the accumulation of neutrophils in the lung is associated with lung injury. This research investigated the effects of a semisynthetic 2-benzoylaminobenzoic acid derivative, methyl 2-(2-fluorobenzamido)benzoate (DSM-RX78), on superoxide anion (O₂⁻) production in formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP)-activated human neutrophils, and on lung injury in Sprague-Dawley rats subjected to trauma-hemorrhage. DSM-RX78 concentration-dependently inhibited O₂⁻ production, but not elastase release, in FMLP-activated human neutrophils. DSM-RX78 displayed no superoxide-scavenging ability, and it failed to alter the subcellular NADPH oxidase activity. Significantly, DSM-RX78 increased cAMP formation and protein kinase (PK)A activity in FMLP-activated neutrophils, which occurred through the selective inhibition of cAMP-specific phosphodiesterase (PDE) activity but not an increase in adenylate cyclase function or cGMP-specific PDE activity. These results show that DSM-RX78 is a new inhibitor of cAMP-specific PDE. Moreover, DSM-RX78 reduced FMLP-induced phosphorylation of protein kinase B (Akt), but not calcium mobilization. The inhibitory effects of DSM-RX78 on O₂⁻ production and Akt phosphorylation were reversed by PKA inhibitors, suggesting that DSM-RX78 regulates O₂⁻ production of human neutrophils by promoting cAMP/PKA-dependent inhibition of Akt activation. On the other hand, administration of DSM-RX78 significantly attenuated the increase in myeloperoxidase activity and edema in the lung, as well as protein concentrations in bronchoalveolar lavage fluid in rats after trauma-hemorrhagic shock. In summary, these results strongly suggest that DSM-RX78 exerts anti-inflammatory effects, which result from the elevation of cAMP levels and PKA activity through its inhibition of cAMP-specific PDE. Also, our findings show that DSM-RX78 attenuates hemorrhagic shock-induced lung injury in rats.     

β-ODAP accumulation could be related to low levels of superoxide anion and hydrogen peroxide in Lathyrus sativus L.

Level of the neuroexcitatory β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP) in grass pea (Lathyrus sativus L.) varies with development and environmental stress. Reactive oxygen species (ROS) (mainly O₂⁻ and H₂O₂) are frequently reported to play important roles in plant development and in response to various stresses. To investigate the possible inter-relationship between contents of β-ODAP and ROS, grass pea leaves have been analyzed for contents of β-ODAP, O₂⁻ and H₂O₂. The results showed that leaves containing high levels of β-ODAP, exhibited low levels of O₂⁻ and H₂O₂, while leaves with high contents of O₂⁻ and H₂O₂ accumulated little β-ODAP. The application of pyridine or ABA which inhibit the production of O₂⁻ or H₂O₂ led to an increase in β-ODAP contents in intact or detached young leaves, whereas inhibition of catalase activity using AT (3-amino-1,2,4-triazole), leading to an increase in H₂O₂ content, result in significant decrease in β-ODAP levels of detached young leaves. In addition, inoculation of Rhizobium to young seedlings enhanced O₂⁻ and H₂O₂ levels, but reduced β-ODAP contents in shoots. These results suggest that β-ODAP accumulation could be related to low levels of superoxide anion and hydrogen peroxide in grass pea tissues.     

Comparative study on antioxidant activity of different varieties of commonly consumed legumes in India

Legumes are rich source of proteins, dietary fiber, micronutrients and bioactive phytochemicals. Thirty different varieties of commonly consumed legumes in India, were screened for phenolic content and antioxidant activity using, radical scavenging [(1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid, (ABTS⁺)], Ferric Reducing Antioxidant Power (FRAP) and metal ion (Fe²⁺) chelation assays. Legumes varied largely in their antioxidant activity. Horse gram, common beans, cowpea (brown and red) and fenugreek showed high DPPH radical scavenging activity (>400 units/g), while lablab bean (cream and white), chickpea (cream and green), butter bean and pea (white and green) showed low antioxidant activity (<125 units/g). Green gram, black gram, pigeon pea, lentils, cowpea (white) and common bean (maroon) showed intermediate activity. Similar trend was observed when the activity was assessed with ABTS⁺ and FRAP assays. Thus most of the varieties having light color seed coat, except soybean exhibited low antioxidant activity. While legumes having dark color seed coat did not always possessed high antioxidant activity (e.g. moth bean, black pea, black gram, lentils). Antioxidant activity showed positive correlation (r² > 0.95) with phenolic contents, in DPPH, ABTS⁺ and FRAP assays, whereas poor correlation (r² = 0.297) was observed between Fe²⁺ chelating activity of the legumes and phenolic contents.     

Edible wild vegetable, Gymnaster koraiensis protects retinal ganglion cells against oxidative stress

This study was conducted to determine whether Gymnaster koraiensis is effective at blunting the negative influence of N-methyl-d-aspartate (NMDA) on the retinas of rats and on oxidative stress induced cell death in transformed retinal ganglion cells (RGC-5).The ethyl acetate fraction of G. koraiensis (EAGK) and the isolated compound, 3,5-di-O-caffeoylquinic acid (3,5-DCQA), were shown to significantly attenuate the negative effect of H₂O₂ on the RGC-5 cells tested by various procedures.The inclusion of EAGK or 3,5-DCQA in the culture reduced the reactive oxygen species (ROS) and replenished the reduced glutathione levels caused by various radical species such as H₂O_2, O₂⁻ or OH. Moreover, EAGK or 3,5-DCQA inhibited lipid peroxidation caused by sodium nitroprusside (SNP) in rat brain homogenates.From in vivo experiments, the presence of NMDA in the retina affected the thickness of the inner plexiform layer (IPL) and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) in positive ganglion cells. EAGK or 3,5-DCQA protected the thinning of the IPL and increased TUNEL positive cells in the ganglion cell layer (GCL).Our results clearly demonstrate the neuroprotective effect of EAGK both in vitro and in vivo. Moreover, 3,5-DCQA is suggested to be the active compound of EAGK.     

Exposure to ZnO nanoparticles induces oxidative stress and cytotoxicity in human colon carcinoma cells

Engineered nanoparticles offer great promise in many industrial and biomedical applications, however little information is available about gastrointestinal toxicity. The purpose of this study was to assess the cytotoxicity, oxidative stress, apoptosis and proinflammatory mediator release induced by ZnO nanoparticles on human colon carcinoma LoVo cells. The biological activity of these particles was related to their physico-chemical characteristics. The physico-chemical characteristics were evaluated by analytical electron microscopy. The cytotoxicity was determined by growth curves and water-soluble tetrazolium assay. The reactive oxygen species production, cellular glutathione content, changes of mitochondrial membrane potential and apoptosis cell death were quantified by flow cytometry. The inflammatory cytokines were evaluated by enzyme-linked immunoadsorbent assay. Treatment with ZnO (5 μg/cm² corresponding to 11.5 μg/ml) for 24 h induced on LoVo cells a significant decrease of cell viability, H₂O₂/OH increase, O2⁻ and GSH decrease, depolarization of inner mitochondrial membranes, apoptosis and IL-8 release. Higher doses induced about 98% of cytotoxicity already after 24 h of treatment. The experimental data show that oxidative stress may be a key route in inducing the cytotoxicity of ZnO nanoparticles in colon carcinoma cells. Moreover, the study of the relationship between toxicological effects and physico-chemical characteristics of particles suggests that surface area does not play a primary role in the cytotoxicity.     

Pycnogenol modulates apoptosis by suppressing oxidative stress and inflammation in high glucose-treated renal tubular cells

Compelling evidence indicates that polyphenolic antioxidants protect against diabetic nephropathy. Pycnogenol is made up of flavonoids, mainly procyanidins and phenolic compounds, and is a known powerful antioxidant. Hyperglycemia is characteristic of diabetic nephropathy and induces renal tubular cell apoptosis. Thus, in this study, we used high glucose-treated renal tubular cells to investigate the protective action of pycnogenol against high glucose-induced apoptosis and diabetic nephropathy. We also sought to further delineate the underlying mechanisms elicited by oxidative stress and inflammation and suppressed by pycnogenol. Results show that pycnogenol significantly suppressed the high glucose-induced morphological changes and the reduction in cell viability associated with cytotoxicity. Bcl2/Bax protein levels indicated pycnogenol’s anti-apoptotic effect against high glucose-induced apoptotic cell death. In addition, several key markers of oxidative stress and inflammation were measured for pycnogenol’s beneficial effects. Results indicate pycnogenol’s anti-oxidative and anti-inflammatory efficacy in suppressing lipid peroxidation, total reactive species (RS), superoxide (O₂), nitric oxide (NO), peroxynitrite (ONOO⁻), pro-inflammatory inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and nuclear factor-kappa B (NF-κB) nuclear translocation. Based on these results, we conclude that pycnogenol’s anti-oxidative and anti-inflammatory properties underlie its anti-apoptotic effects, suggesting further investigation of pycnogenol as a promising treatment against diabetic nephropathy.     

Arsenic alters monocyte superoxide anion and nitric oxide production in environmentally exposed children

Arsenic (As) exposure has been associated with alterations in the immune system, studies in experimental models and adults have shown that these effects involve macrophage function; however, limited information is available on what type of effects could be induced in children. The aim of this study was to evaluate effects of As exposure, through the association of inorganic As (iAs) and its metabolites [monomethylated arsenic (MMA) and dimethylated arsenic (DMA)] with basal levels of nitric oxide (NO⁻) and superoxide anion (O₂⁻), in peripheral blood mononuclear cells (PBMC) and monocytes, and NO⁻ and O₂⁻ produced by activated monocytes. Hence, a cross-sectional study was conducted in 87 children (6-10 years old) who had been environmentally exposed to As through drinking water. Levels of urinary As species (iAs, MMA and DMA) were determined by hydride generation atomic absorption spectrometry, total As (tAs) represents the sum of iAs and its species; tAs urine levels ranged from 12.3 to 1411 μg/g creatinine. Using multiple linear regression models, iAs presented a positive and statistical association with basal NO⁻ in PBMC (β = 0.0048, p = 0.049) and monocytes (β = 0.0044, p = 0.044), while basal O₂⁻ had a significant positive association with DMA (β = 0.0025, p = 0.046). In activated monocytes, O₂⁻ showed a statistical and positive association with iAs (β = 0.0108, p = 0.023), MMA (β = 0.0066, p = 0.022), DMA (β = 0.0018, p = 0.015), and tAs (β = 0.0013, p = 0.015). We conclude that As exposure in the studied children was positively associated with basal levels of NO⁻ and O₂⁻ in PBMC and monocytes, suggesting that As induces oxidative stress in circulating blood cells. Additionally, this study showed a positive association of O₂⁻ production with iAs and its metabolites in stimulated monocytes, supporting previous data that suggests that these cells, and particularly the O₂⁻ activation pathway, are relevant targets for As toxicity.     

Antioxidant and anti-neoplastic activities of Picrorhiza kurroa extracts

Picrorhizakurroa Royle ex Benth., a well-known traditional herb from the Scrophulariaceae family has a remarkable reputation among the indigenous medical practitioners. The antioxidant and anti-neoplastic activities of methanolic and aqueous extracts of P. kurroa rhizome were investigated in the present study. The total phenolic content was determined by a spectrophotometric method. The antioxidant efficacies of the extracts were studied employing radical scavenging assays (DPPH and OH), ferric reducing antioxidant property (FRAP) and thiobarbituric acid (TBA) assay for testing inhibition of lipid peroxidation. Furthermore, the cytotoxicity of the extracts was tested by XTT assay in MDA-MB-435S (human breast carcinoma), Hep3B (human hepatocellular carcinoma) and PC-3 (human prostate cancer) cell lines. The ability of the extracts to induce apoptosis was also investigated. Both extracts exhibited promising antioxidant potentials. The extracts were also observed to be cytotoxic at the tested dosage and were able to target cells towards apoptosis. The study concludes that P. kurroa possess diverse therapeutic potentials which might be useful in development of drugs or their precursors.