Protective effect of isorhamnetin 3-О-β-d-glucopyranoside from Salicornia herbacea against oxidation-induced cell damage

Isorhamnetin 3-О-β-d-glucopyranoside (1) was isolated from Salicornia herbacea. The inhibitory effects of compound 1 on oxidative stress were evaluated in free-cellular and cellular systems. An increased concentration of compound 1 not only exhibited dose-dependent scavenging activities on the generation of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and carbon-centered radicals, but also significantly decreased levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner. Further, antioxidative mechanisms by compound 1 were examined by measuring the intracellular glutathione (GSH) level and expression levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione reductase and heme oxygenase-1 (HO-1). Compound 1 significantly elevated GSH level as well as expression levels of antioxidant enzymes which were closely related with amount of cellular ROS. In addition, it significantly inhibited oxidative damage of purified genomic DNA and suppressed activity of myeloperoxidase (MPO), a generator of potent oxidant (hypochlorous acid), in tumor necrosis factor-α (TNF-α) stimulated human myeloid cells. Therefore, these results suggested that compound 1 has a therapeutic effectiveness in prevention of ROS-induced cellular damage and is a candidate worthy of being developed as a potential natural antioxidant related to oxidative stress.     

Hop proanthocyanidins induce apoptosis,protein carbonylation,and cytoskeleton disorganization in human colorectal adenocarcinoma cells via reactive oxygen species

Proanthocyanidins (PCs) have been shown to suppress the growth of diverse human cancer cells and are considered as promising additions to the arsenal of chemopreventive phytochemicals. An oligomeric mixture of PCs from hops (Humulus lupulus) significantly decreased cell viability of human colon cancer HT-29 cells in a dose-dependent manner. Hop PCs, at 50 or 100 μg/ml, exhibited apoptosis-inducing properties as shown by the increase in caspase-3 activity. Increased levels of intracellular reactive oxygen species (ROS) was accompanied by an augmented accumulation of protein carbonyls. Mass spectrometry-based proteomic analysis in combination with 2-alkenal-specific immunochemical detection identified β-actin and protein disulfide isomerase as major putative targets of acrolein adduction. Incubation of HT-29 cells with hop PCs resulted in morphological changes that indicated disruption of the actin cytoskeleton. PC-mediated hydrogen peroxide (H₂O₂) formation in the cell culture media was also quantified; but, the measured H₂O₂ levels would not explain the observed changes in the oxidative modifications of actin. These findings suggest new modes of action for proanthocyandins as anticarcinogenic agents in human colon cancer cells, namely, promotion of protein oxidative modifications and cytoskeleton derangement.     

Catalase and glutathione peroxidase mimics

Overproduction of the reactive oxygen species (ROS) superoxide (O₂⁻) and hydrogen peroxide (H₂O₂) are increasingly implicated in human disease and aging. ROS are also being explored as important modulating agents in a number of cell signaling pathways. Earlier work has focused on development of small catalytic scavengers of O₂⁻, commonly referred to as superoxide dismutase (SOD) mimetics. Many of these compounds also have substantial abilities to catalytically scavenge H₂O₂ and peroxynitrite (ONOO⁻). Peroxides have been increasingly shown to disrupt cell signaling cascades associated with excessive inflammation associated with a wide variety of human diseases. Early studies with enzymatic scavengers like SOD frequently reported little or no beneficial effect in biologic models unless SOD was combined with catalase or a peroxidase. Increasing attention has been devoted to developing catalase or peroxidase mimetics as a way to treat overt inflammation associated with the pathophysiology of many human disorders. This review will focus on recent development of catalytic scavengers of peroxides and their potential use as therapeutic agents for pulmonary, cardiovascular, neurodegenerative and inflammatory disorders.     

Expression of cytosolic NADP(+)-dependent isocitrate dehydrogenase in melanocytes and its role as an antioxidant

Background

Cytosolic NADP⁺-dependent ICDH (IDPc) has an antioxidant effect as a supplier of NADPH to the cytosol, which is needed for the production of glutathione.

Objective

To evaluate the expression of IDPc in melanocytes and to elucidate its role as an antioxidant.

Methods

The knock-down of IDPc expression in immortalized mouse melanocyte cell lines (melan-a) was performed using the short interfering RNA (siRNA)-targeted gene silencing method. After confirming the silencing of IDPc expression with mRNA and protein levels, viability, apoptosis and necrosis, as well as ROS production in IDPc-silenced melanocytes were monitored under conditions of oxidative stress and non-stress. Also, the ratio of oxidized glutathione to total glutathione was examined, and whether the addition of glutathione recovered cell viability, decreased by oxidant stress, was checked.

Results

The expression of IDPc in both primary human melanocytes and melan-a cells was confirmed by Western blot and RT-PCR. The silencing of IDPc expression by transfecting IDPc siRNA in melan-a cells was observed by Western blotting and real-time RT-PCR. IDPc knock-down cells showed significantly decreased cell viability and an increased number of cells under apoptosis and necrosis. IDPc siRNA-treated melanocytes demonstrated a higher intensity of DCFDA after the addition of H₂O₂ compared with scrambled siRNA-treated melanocytes, and a lower ratio of reduced glutathione to oxidized glutathione were observed in IDPc siRNA transfected melanocytes. In addition, the addition of glutathione recovered cell viability, which was previously decreased after incubation with H₂O₂.

Conclusions

This study suggests that decreased IDPc expression renders melanocytes more vulnerable to oxidative stress, and IDPc plays an important antioxidant function in melanocytes.     

Protective effect of diallyl trisulfide on liver in rats with sepsis and the mechanism

The protective effects of diallyl trisulfide on liver were examined in rats with sepsis. Sepsis was reproduced in rats by cecum ligation and puncture (CLP). Fifty-six male Wistar rats were randomly divided into sham-operated group (group S, n=8), sepsis model group (group C, n=24), diallyl trisulfide (DATS)-treated group (group D, n=24). Animals in groups C and D were further divided into three subgroups according to different observation time points, with 8 rats in each sub-group.Rats in group D and C were intravenously injected with normal saline or DATS respectively at a dose of 20 mg/kg after the establishment of sepsis model. Eight rats in groups C and D were sacrificed at 3, 6 and 24 h post-CLP and their livers were harvested for detection of interleukin (IL)-1 receptor associated kinase-4 (IRAK-4), nuclear factor-κB (NF-κB), c-fos, c-jun, malondialdehydethhe (MDA) and superoxide dismutase (SOD), tumor necrosis factor alpha (TNF-α) and for pathological examination. The results showed that the levels of serum IRAK-4, NF-κB and TNF-α in hepatic tissues were higher in group C than group S (control group) (P<0.05). After DATS treatment, the levels of IRAK-4 and NF-κB in the hepatic tissues and serum TNF-α in group D were lower than those in group C (P<0.05). The levels of c-fos and c-jun and MDA in the hepatic tissues were higher in group C than in group S (P<0.05). After DATS treatment, the levels of c-fos and c-jun and MDA in the hepatic tissues were significantly lower in group D than in group C (P<0.05). When compared with group S group, concentration of SOD in the hepatic tissues in group C was significantly lower (P<0.05). After DATS treatment, the concentration of SOD in the hepatic tissues was higher in group D than in group C (P<0.05). These findings suggested that treatment with DATS could ameliorate sepsis-induced liver injury in rats. The protective effect might be related to its ability to inhibit the signal pathway of IRAK-4 and NF-κB, thereby decreasing the production o     

Maternal serum thiol/disulfide homeostasis in pregnancies complicated by neural tube defects: report of a preliminary study

Objective: To determine and evaluate the maternal serum thiol/disulfide homeostasis in pregnancies complicated by neural tube defects (NTD) via a novel method.

Methods: Seventy-three pregnant women with NTD (study group) and seventy-one healthy control pregnant women (control group) were included in the study. A new and fully automated method was used to measure plasma native thiol, total thiol and disulfide levels, based on the reduction of dynamic disulfide bonds to functional thiol groups by sodium borohydrate.

Results: The study and control groups were gestational age-matched. There were no statistical differences in demographic variables regarding age, gravidity, parity and body mass index. The serum native thiol levels (–SH) were 360.5?±?50.3 and 353.3?±?31.0?μmol/l in study and control groups, respectively, which was not statistically different (p?=?0.308). The native thiol/total thiol, disulfide/native thiol and disulfide/total thiol ratios were not statistically significantly different (p?>?0.05).

Conclusion: Our preliminary results show that maternal serum thiol/disulfide homeostatis does not change in pregnancies complicated by NTD. Larger further studies are required to evaluate the relation of oxidative stress and development of NTD.     

二烯丙基二硫诱导肿瘤细胞G2/M 期阻滞的分子机制

二烯丙基二硫（diallyl disulfide,DADS) 对乳腺癌、肺癌、膀胱癌、结肠癌、胃癌、白血病等许多肿瘤均有明显的抑制作用,其作用与G2/M 期阻滞有关。DADS阻滞G2/M 期的分子机制包括抑制p34cdc2的活性,激活MAPK信号通路,增加p21WAF1/cip1蛋白表达与ROS生成等。     

TAP-translocated peptides specifically bind proteins in the endoplasmic reticulum,including gp96, protein disulfide isomerase and calreticulin

The endoplasmic reticulum (ER) membrane-embedded transporter associated with antigen processing (TAP) associates with peptides in the cytosol and translocates these into the ER lumen. Here, MHC class I molecules bind a subset of these peptides and the remainder is either removed or degraded, or may be retained in the ER in association with other proteins. We have visualized peptide-binding proteins in the ER using radioactive peptides with a photoreactive group. Besides TAP, two proteins were identified as gp96 and protein disulfide isomerase (PDI). Calreticulin, previously found in complex with TAP, only binds glycosylated peptides. In addition, two as yet unidentified, ER luminal glycoproteins (gp120 and gp170) were visualized. The effects of peptide size and sequence on binding to the ER-resident proteins were studied by using partially degenerated peptides with photoreactive side chains. All identified proteins were able to bind peptides within the size range of peptides translocated by TAP, from 8 to more than 20 amino acids. Whereas PDI associated with all peptides tested, gp96 and gp120 showed a clear sequence preference for non-charged amino acids at positions 2 and 9 in 9mer peptides. Thus various ER proteins, other than the MHC class I heterodimer and TAP, are able to interact with peptides albeit with a different substrate selectivity.     

The properties of mesoporous silica nanoparticles functionalized with different PEG-chain length via the disulfide bond linker and drug release in glutathione medium

In this paper, a novel drug-loaded material (MSNs-SS-PEG) was obtained by grafting the thiol-linked methoxy polyethylene glycol (MeOPEG-SH) onto the thiol-functionalized mesoporous silica nanoparticles (MSNs-SH) via the disulfide bond linker. In our designed experiment, three different chain lengths of PEG (PEG₁₀₀₀, PEG₅₀₀₀, and PEG₁₀₀₀-PEG₅₀₀₀) were used. The silica materials were characterized by Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, field emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption measurements, and X-ray diffraction. The morphology of the MSNs-SS-PEG was spherical with an average diameter of about 150 nm. Due to the covalent modification of hydrophilic MeOPEG, the MSNs-SS-PEG was coated by a thin polymer shell, showing stable and inerratic MCM-41 type mesoporous structure as well as high specific surface areas and large pore volumes. Moreover, the releases of doxorubicin hydrochloride (DOX) from these materials at 10 mM of glutathione were investigated. The PEG functionalization could effectively cap drugs in the mesoporous channels. The release of DOX from the MSNs-SS-PEG_n revealed redox-responsive characteristic. The obtained results showed that the MSNs-SS-PEG might be promising drug delivery carrier materials, which could play an important role in the development of drug delivery.