Hang Qi

Involvement of intracellular oxidative stress-sensitive pathway in phloxine B-induced photocytotoxicity in human T lymphocytic leukemia cells.

We investigated the molecular mechanisms underlying phloxine B (PhB)-induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. In addition to apoptosis-related biochemical events, photo-irradiated PhB generated intracellular reactive oxygen species (ROS), induced phosphorylation of c-Jun-N-terminal kinase (JNK) in an oxidative stress-dependent manner and up-regulated the gene expression of interferon (IFN)-γ, an inducer of diverse apoptosis-related molecules in activated T cells. PhB-induced apoptosis was significantly inhibited by N-acetyl-l-cysteine, but not by catalase, indicating that ROS generation occurred intracellularly, and by SP600125 and AG490, specific inhibitors of JNK and IFN-γ signaling, respectively, confirming their roles in the apoptotic pathway. IFN-γ up-regulation was also inhibited by SP600125, indicating that it was downstream of JNK activation. These results suggest that PhB-induced apoptosis in Jurkat cells partially involves the intracellular oxidative stress-sensitive and T cell-specific IFN-γ pathway. These data present a novel insight into the mechanisms of photocytotoxicity induced by artificial food colorants in human T lymphocytic leukemia cells.

(−)-Epigallocatechin-3-Gallate Ameliorates Photodynamic Therapy Responses in an In Vitro T Lymphocyte Model

(−)‐Epigallocatechin‐3‐gallate (EGCG), the most abundant polyphenolic constituent in green tea, is known as a powerful antioxidant but concomitantly possesses a prooxidant property. We investigated the effect of EGCG on phloxine B (PhB)‐induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. EGCG significantly potentiated PhB‐induced photocytotoxic effects, including the inhibition of cell proliferation, DNA fragmentation, and caspase‐3 activity induction in Jurkat cells. Catalase attenuated the enhanced cytotoxicity by EGCG, suggesting the involvement of extracellularly produced hydrogen peroxide. Indeed, EGCG significantly enhanced extracellular hydrogen peroxide formation induced by photo‐irradiated PhB. The EGCG also enhanced intracellular reactive oxygen species accumulation, c‐Jun N‐terminal kinase (JNK) phosphorylation, and interferon‐γ (IFN‐γ) gene expression, all of which are involved in PhB‐induced apoptosis. Taken together, our data suggest that EGCG is capable of potentiating photodynamic therapy responses, presumably through the intracellular oxidative stress‐sensitive JNK/IFN‐γ pathway by exogenous hydrogen peroxide formation. Copyright

Apoptosis induction is involved in UVA-induced autolysis in sea cucumber Stichopus japonicus.

Autolysis easily happens to sea cucumber (Stichopus japonicus, S. japonicus) for external stimulus like UV exposure causing heavy economic losses. Therefore, it is meaningful to reveal the mechanism of S. japonicas autolysis. In the present study, to examine the involvement of apoptosis induction in UVA-induced autolysis of S. japonicas, we investigated the biochemical events including the DNA fragmentation, caspase-3 activation, mitogen-activated protein kinases (MAPKs) phosphorylation and free radical formation. Substantial morphological changes such as intestine vomiting and dermatolysis were observed in S. japonicus during the incubation after 1-h UVA irradiation (10W/m(2)). The degradation of the structural proteins and enhancement of cathepsin L activity were also detected, suggesting the profound impact of proteolysis caused by the UVA irradiation even for 1h. Furthermore, the DNA fragmentation and specific activity of caspase-3 was increased up to 12h after UVA irradiation. The levels of phosphorylated p38 mitogen activated protein kinase (MAPK) and phosphorylated c-Jun.-N-terminal kinase (JNK) were significantly increased by the UVA irradiation for 1h. An electron spin resonance (ESR) analysis revealed that UVA enhanced the free radical formation in S. japonicas, even through we could not identify the attributed species. These results suggest that UVA-induced autolysis in S. japonicas at least partially involves the oxidative stress-sensitive apoptosis induction pathway. These data present a novel insight into the mechanisms of sea cucumber autolysis induced by external stress.

ROS production in homogenate from the body wall of sea cucumber Stichopus japonicus under UVA irradiation: ESR spin-trapping study

Sea cucumber Stichopus japonicus (S. japonicus) shows a strong ability of autolysis, which leads to severe deterioration in sea cucumber quality during processing and storage. In this study, to further characterize the mechanism of sea cucumber autolysis, hydroxyl radical production induced by ultraviolet A (UVA) irradiation was investigated. Homogenate from the body wall of S. japonicas was prepared and subjected to UVA irradiation at room temperature. Electron Spin Resonance (ESR) spectra of the treated samples were subsequently recorded. The results showed that hydroxyl radicals (OH) became more abundant while the time of UVA treatment and the homogenate concentration were increased. Addition of superoxide dismutase (SOD), catalase, EDTA, desferal, NaN3 and D2O to the homogenate samples led to different degrees of inhibition on OH production. Metal cations and pH also showed different effects on OH production. These results indicated that OH was produced in the homogenate with a possible pathway as follows: O2(-) → H2O2 → OH, suggesting that OH might be a critical factor in UVA-induced S. japonicus autolysis.

Artificial food colorants inhibit superoxide production in differentiated HL-60 cells.

We tested synthetic food colorants for their antioxidative potential by the in vitro superoxide generation assay in differentiated HL-60 cells in response to phorbol ester. Among the 12 colorants tested, such fluorescein-type red colorants as rose bengal showed potent inhibitory activity without any cytotoxicity under dark conditions. The intracellular accumulation and superoxide anion scavenging effect of rose bengal were at least partly involved in the inhibitory activity.

Ascorbic Acid Synergistically Potentiates Phloxine B-induced Photocytotoxicity in Human Acute Promyelocytic Leukemia Cells

Ascorbic acid (AsA) is known as an antioxidant but concomitantly possesses a pro‐oxidant property. Because the impact of AsA on photodynamic therapy response is unclear, we investigated the effect of AsA on photocytotoxicity induced by phloxine B in human acute promyelocytic leukemia HL‐60 cells. AsA synergistically enhanced phloxine B‐induced photocytotoxic effects, including inhibition of cell proliferation, DNA ladder formation, and caspase‐3 activation, whereas AsA itself showed no photocytotoxicity. AsA also enhanced the consumption of the reduced glutathione level compared with the cells treated with phloxine B alone under the light condition. Combination of AsA with phloxine B under the light condition enhanced the phosphorylation of c‐Jun N‐terminal kinase and p38 mitogen‐activated protein kinase (MAPK). These effects were completely cancelled by catalase. These results suggest that AsA synergistically enhances phloxine B‐induced photocytotoxicity, possibly through the extracellular oxidative stress‐dependent MAPK pathway activation.

Structural and biochemical changes in dermis of sea cucumber (Stichopus japonicus) during autolysis in response to cutting the body wall

The autolysis of sea cucumber body wall is caused by endogenous proteolysis of its structural elements. However, changes in collagen fibrils, collagen fibres and microfibrils, the major structural elements in sea cucumber body wall during autolysis are less clear. Autolysis of sea cucumber (S. japonicus) was induced by cutting the body wall, and the structural and biochemical changes in its dermis were investigated using electron microscopy, differential scanning calorimetry, infrared spectroscopy, electrophoresis, and chemical analysis. During autolysis, both collagen fibres and microfibrils gradually degraded. In contrast, damage to microfibrils was more pronounced. Upon massive autolysis, collagen fibres disaggregated into collagen fibril bundles and individual fibrils due to the fracture of interfibrillar bridges. Meanwhile, excessive unfolding of collagen fibrils occurred. However, there was only slight damage to collagen monomers. Therefore, structural damage in collagen fibres, collagen fibrils and microfibrils rather than monomeric collagen accounts for autolysis of S. japonicus dermis.

Removal of heavy metals in aqueous solution using Antarctic krill chitosan/hydroxyapatite composite

Discarded Antarctic krill shells can be used to prepare chitosan and adsorption materials in an attempt to save resource and protect environment. The optimal conditions of composite materials preparation were as follows: mass ratio of CS and HA was 2:1 at 40 °C, pH 10–10.5, volume ratio of chitosan and Ca(NO3)2 was 2:1 over a period of 1 day. Under these conditions, the Cr (VI) removal rate was about 75±8 %. SEM, TEM, XRD, FTIR, DT-TGA analysis indicated that CS/HA composite was made up of CS and HA and it possessed good mechanical strength and thermal stability. The ability to remove Cd (II), Cr (III) and Cu (II) in aqueous was high, and the optimal conditions were as follows: a contact time of 60 min at 35 °C and pH 6–7. The removal rates of all three heavy metals were above 90 %.

Oxidative stress-induced textural and biochemical changes of scallop Patinopecten yessoensis adductor muscle under heat treatment

ABSTRACT In this study, the effects of heat treatment (45°C and 65°C, respectively) on the quality of Patinopecten yessoensis adductor muscle (PYAM) were investigated. Water mobility in PYAM samples was analyzed using low-field nuclear magnetic resonance. The texture of treated PYAM was analyzed using texture profile analysis. Protein degradation was characterized using SDS-PAGE. Activities of cathepsin L (CL), superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were determined using chemical analysis methods. The production of free radicals was measured using electron spin resonance. It was revealed that water mobility in PYAM samples increased with the extension of heated time. Cohesiveness of PYAM was higher in samples heated at 65°C than at 45°C, while hardness showed an opposite trend, higher in the samples heated at 45°C than at 65°C. The degradation of structural proteins was more severe in the samples heated at 65°C than at 45°C, with the greater CL activity being observed. It was also found that heating caused elevation in T-SOD, GSH-Px, and CAT enzyme activities. Considering the chemical changes in the PYAM samples, contents of carbonyl and malonaldehyde increased, but sulfhydryl content decreased with heating. Level of free radicals increased significantly from 6 h on after heat treatment, with higher level at 65°C than at 45°C. These results suggested that oxidative stress is directly involved in quality changes during heat treatment of PYAM.

Physicochemical Properties and the Radical Scavenging Capacities of Pepsin-Solubilized Collagen from the Body Wall of Starfish (Asterina pectinifera)

ABSTRACT Pepsin-soluble collagen was successfully prepared from the body wall of starfish (Asterina pectinifera) (PSCBWS). Amino acid composition suggested that the collagen might be classified as type I collagen. Ultraviolet-visible and Fourier transform infrared spectroscopic analyses showed that the PSCBWS was a high-purity collagen that maintained the intact triple-stranded helices. Physical and chemical characterizations of the PSCBWS showed an isoelectric point (pI) of 5.0 ± 0.2, superior moisture-absorption and retention capacities compared with glycerol, a minimum solubility at pH 5.0 in 0.5 M acetic acid, and a sharp decrease in solubility in the presence of low concentration of NaCl. The PSCBWS was evaluated for antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and hydroxyl radicals. Results indicated that PSCBWS possessed DPPH and hydroxyl radicals scavenging capacity in a dose-dependent manner. These results indicated that PSCBWS might be used as a new collagen resource in the food and cosmetic industries.