Astaxanthin ameliorates dopaminergic neuron damage in paraquat-induced SH-SY5Y cells and mouse models of Parkinson's disease.

Parkinson's disease (PD) is the second largest neurodegenerative disorder caused by the decreased number of dopaminergic (DAc) neurons in the substantia nigra pars compacta (SNpc). There is evidence that oxidative stress can contribute degeneration of DAc neurons in SNpc which is mainly caused by apoptotic cell death. Thus, suppressing oxidative stress and apoptosis of DAc neurons is an effective strategy to mitigate the progress of PD. Astaxanthin (AST) is a carotenoid, which mainly exists in marine organisms and is a powerful biological antioxidant. In this study, we aimed to determine the neuroprotective effect of AST on paraquat (PQ) -induced models of PD in vitro and in vivo. Here, we showed that AST significantly enhanced cell survival of SH-SY5Y cells against PQ toxicity by suppressing apoptotic cell death and oxidative stress. Moreover, we found that AST significantly ameliorated PQ-induced behavioral disorders associated with PD in C57BL/6 J mice and the damage to DAc neurons in the SNpc of mice. Lastly, we found that the neuroprotective effects of AST were conducted through inhibiting PQ-induced activation of MAPK signaling. In conclusion, our study indicates that AST had a strong protective effect on PQ-induced oxidative stress and antagonized apoptotic cell death in SH-SY5Y cells and PQ-induced mice PD model, which might provide new insights of AST for PD treatment.

Iron-based and BRD4-downregulated strategy for amplified ferroptosis based on pH-sensitive/NIR-II-boosted nano-matchbox.

Ferroptosis (FPT), a novel form of programmed cell death, is characterized by overwhelming iron/reactive oxygen species (ROS)-dependent accumulation of lipid peroxidation (LPO). However, the insufficiency of endogenous iron and ROS level limited the FPT therapeutic efficacy to a large extent. To overcome this obstacle, the bromodomain-containing protein 4 (BRD4)-inhibitor (+)-JQ1 (JQ1) and iron-supplement ferric ammonium citrate (FAC)-loaded gold nanorods (GNRs) are encapsulated into the zeolitic imidazolate framework-8 (ZIF-8) to form matchbox-like GNRs@JF/ZIF-8 for the amplified FPT therapy. The existence of matchbox (ZIF-8) is stable in physiologically neutral conditions but degradable in acidic environment, which could prevent the loaded agents from prematurely reacting. Moreover, GNRs as the drug-carriers induce the photothermal therapy (PTT) effect under the irradiation of near-infrared II (NIR-II) light owing to the absorption by localized surface plasmon resonance (LSPR), while the hyperthermia also boosts the JQ1 and FAC releasing in the tumor microenvironment (TME). On one hand, the FAC-induced Fenton/Fenton-like reactions in TME can simultaneously generate iron (Fe3+/Fe2+) and ROS to initiate the FPT treatment by LPO elevation. On the other hand, JQ1 as a small molecule inhibitor of BRD4 protein can amplify FPT through downregulating the expression of glutathione peroxidase 4 (GPX4), thus inhibiting the ROS elimination and leading to the LPO accumulation. Both in vitro and in vivo studies reveal that this pH-sensitive nano-matchbox achieves obvious suppression of tumor growth with good biosafety and biocompatibility. As a result, our study points out a PTT combined iron-based/BRD4-downregulated strategy for amplified ferrotherapy which also opens the door of future exploitation of ferrotherapy systems.

Neurotoxicity of ß-HgS differs from environmental mercury pollutants (MeHgCl and HgCl2) in Neuro-2a cell.

ß-HgS, differing from environmental mercury pollutants (MeHgCl and HgCl2) in chemical form, is used as traditional medicine in Asian countries for thousands of years. In this study, Neuro-2a cells were exposed to ß-HgS, MeHgCl and HgCl2 (5 µM) for 6-24 h. The cell viability of ß-HgS was higher than MeHgCl with 25.9% and 72.4% in 12 h and 24 h respectively. As the incubation time increased, MeHgCl had obvious damage to cell morphology, decreased the ratio of Bcl-2 and Bak and increased the expressions of TNF-α, IL-6 and IL-1ß significantly. Furthermore, the expressions of IL-1ß and IL-6 in HgCl2 group were increased significantly in 6 h and 24 h. The apoptotic rates in MeHgCl and HgCl2 group were respectively higher than ß-HgS with 32.2% and 7.30% in 24 h. Our findings indicate that ß-HgS is much less neurotoxicity than MeHgCl and HgCl2 in Neuro-2a cells.

Effects of ß-HgS on cell viability and intracellular oxidative stress in PC-12 cells.

Traditional Tibetan medicines containing ß-HgS have been used to treat chronic ailments for thousands of years. However, there has recently been speculation regarding the safety of these medicines due to their high mercury content. Although the toxic effect of ß-HgS has been previously investigated in vivo, the mechanism underlying the toxicity of this compound remains unclear. In this study, we investigate the mechanism of ß-HgS cytotoxicity via experiments performed on rat adrenal gland tumor cells (PC-12). Specifically, we analyze the viability and intracellular oxidative stress state of PC-12 cells treated with varying concentrations of ß-HgS. For comparison purposes, the effects of MeHgCl and HgCl2, two Hg-based compounds, on ROS generation and MDA, GSH/GSSG, Nrf2, NQO-1, and HO-1 levels are also determined. It should be noted that we used the small-molecule thiols of cell culture medium, such as cysteine, to increase the solubility of ß-HgS and prepare a ß-HgS solution to treat PC-12 cells. The obtained results show that ß-HgS inhibits cell viability at concentrations of 200-1000 ng Hg mL-1 (48 h treatment). In the concentration range of 200-600 ng Hg mL-1 (24 h treatment), the inhibitory effect of ß-HgS is stronger than that of MeHgCl; however, this trend is reversed at higher concentrations (800-1000 ng mL-1) and longer exposure times (48 h). Moreover, ß-HgS significantly promotes MDA, but has no appreciable influence on cell apoptosis and ROS generation in PC-12 cells, which suggests that its inhibitory effect on cell viability might be related to the stimulation of ROS-independent oxidative stress. Notably, ß-HgS and HgCl2 significantly increase the GSH content, GSH/GSSG ratio, NQO-1 mRNA expression, and HO-1 protein expression in PC-12 cells, indicating that the antioxidant protection against these compounds is triggered by Nrf2 activation. HPLC-AFS analysis shows that in ß-HgS and HgCl2 solutions, mercury exists in the same form of Hg2+, but the cytotoxicity of the former is greater. This is probably due to the additional oxidative damage induced by the S2- ion in ß-HgS. In conclusion, ß-HgS induces ROS-independent oxidative stress in PC-12 cells, and thus, is obviously cytotoxic. At the same time, it promotes the antioxidant capacity of cells by activating the Nrf2 pathway.

Hormesis of methylmercury-human serum albumin conjugate on N9 microglia via ERK/MAPKs and STAT3 signaling pathways.

Methylmercury (MeHg+) is an extremely toxic organomercury cation that can induce severe neurological damage. Once it enters the body, methylmercury binds to amino acids or proteins containing free sulfhydryl groups. In particular, methylmercury is known to bind with human serum albumin (HSA) in human plasma; however, the effects of methylmercury-HSA conjugate (MeHg-HSA) on the central nervous system (CNS) are not fully understood. In the present study, we used the microglial cell line N9 as the target cells to evaluate the effect of MeHg-HSA on physiological function of the CNS preliminarily. The various factors in the cell culture were monitored by MTT assay, total lactate dehydrogenase assay, ELISA, qPCR, Western blot and flow cytometry techniques. The results showed that low-dose treatment with MeHg-HSA activated N9 cells, promoting cell proliferation and total cell number, enhancing NO and intracellular Ca2+ levels, and suppressing the release of TNFα and IL1ß without cytotoxic effects; while high-dose MeHg-HSA exhibited cytotoxic effects on N9 cells, including promoting cell death and increasing the secretion of TNFα and IL1ß. These results indicate that MeHg-HSA causes hormesis in microglia N9 cells. Furthermore, ERK/MAPKs and STAT3 signaling pathways related to the hormesis of MeHg-HSA on N9 cells. In addition, low dose of MeHg-HSA might be viewed as something very close to a lowest observed adverse effect level (LOAEL) for N9 cells. These findings will be useful for investigating the hormesis mechanism of MeHg+ and exploring the specific functions of MeHg-sulfhydryl conjugates on the central nervous system.

Medium optimization, molecular characterization, and bioactivity of exopolysaccharides from Pleurotus eryngii.

An optimal medium for exopolysaccharides (EPS) production was obtained through one-factor-at-a-time method and response surface methodology. Under optimal culture medium, the maximum EPS concentration in shake flask was 5.16 g/l. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography/multiangle laser light scattering, and the weight average molar masses (M w) of Fr-I and Fr-II were determined to be 4.098 × 10(4) and 1.114 × 10(4) g/mol, respectively. The molecular confirmation of Fr-I was revealed to be a rigid rod form in aqueous solution. Moreover, monosaccharide composition and characteristic groups were investigated by GC and Fourier transform infrared, respectively. Finally, pharmacology experiment in vitro indicated EPS Fr-II of Pleurotus eryngii exhibited higher antioxidant and antitumor abilities than Fr-I, which might be attributed to the different molecular weights and chemical compositions in the EPS fraction.

Production, fractionation, characterization of extracellular polysaccharide from a newly isolated Trametes gibbosa and its hypoglycemic activity.

The submerged fermentation for extracellular polysaccharide (EPS) production from Trametes gibbosa was optimized. An optimal medium for EPS production was obtained through central composite design (CCD) as follows: 53.12 g/L maltose and 4.21 g/L polypeptone in distilled water. Furthermore, four groups of EPSs (designated as Fr-I, Fr-II, Fr-III and Fr-IV) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar mass of Fr-I was determined to be 3.872 x 10(5)g/mol and its molecular shape was revealed to be a rigid rod in an aqueous solution. Finally, the hypoglycemic effect of the EPS, investigated in streptozotocin induced diabetic mice, decreased plasma glucose, total cholesterol and triacylglycerol concentrations by 17.4%, 14.0% and 12.6%, respectively. The results indicate the potential of this EPS to prevent hyperglycemia in diabetic patients.

Production of extracellular polysaccharides by the medicinal mushroom Trametes trogii (higher Basidiomycetes) in stirred-tank and airlift reactors.

Extracellular polysaccharides (EPSs) produced by submerged culture of Trametes trogii exhibit antioxidant and antitumor activities. In this study, mycelial growth and EPS production of T. trogii were investigated using optimal culture conditions (maltose [53.12 g/L] and polypeptone [4.21 g/L] in distilled water) in a 5-L jar fermenter. Maximum biomass growth (10.81 g/L) occurred after 5 days of cultivation, whereas maximal EPS yield (1.86 g/L) was achieved after 5 days in a 5-L stirred-tank reactor. Furthermore, the morphological parameters (i.e., mean diameter, circularity, roughness, and compactness) of the pellets and the viscosity of the broth were characterized. It was proved that the compactness of the pellets were significantly positively correlated with EPS content.

Production, preliminary characterization, and bioactivities of exopolysaccharides from Pleurotus geesteranus 5(#).

The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Pleurotus geesteranus 5(#) were determined using an orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g maltose, 5.0 g tryptone, 1 mM NaCl, 5 mM KH(2)PO(4), and initial pH 6.0 at 28 °C. In the optimal culture medium, the maximum EPS production was 16.97 g/L in a shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The approximate weight-average molar masses of the Fr-I and Fr-II of EPS were determined to be 3.263 × 10(4) and 5.738 × 10(3) g/mol, respectively. The low values of polydispersity ratio (1.176 and 1.124 for Fr-I and Fr-II, respectively) of EPSs mean that these EPS molecules exist much less dispersed in aqueous solution without forming large aggregates. Furthermore, the experiments in vitro indicated that P. geesteranus 5(#) EPS exhibit high antitumor and antioxidative effects.

Production, purfication, molecular characterization and bioactivities of exopolysaccharides produced by the wine cap culinary-medicinal mushroom, Stropharia rugosoannulata 2# (higher Basidiomycetes).

The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Stropharia rugosoannulata 2# were determined using the orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g sucrose, 6.0 g tryptone, 5 mM KH2PO4, and initial pH 7.0 at 28°C. In the optimal culture medium, the maximum EPS production was 9.967 g/L in shake-flask culture. One fraction of EPS was purified from the culture filtrates by size exclusion chromatography (SEC), and the molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar masses and the polydispersity ratio of the EPS fraction were determined to be 5.305 × 103 g/mol and 2.014, respectively. FTIR spectroscopy was used for obtaining vibrational spectra of the purified EPS fraction. The obvious characteristic absorption at 884.3 cm-1 revealed the existence of ß configuration. Furthermore, the experiments in vitro indicated that S. rugosoannulata 2# EPS exhibit high antitumor and antioxidative effects.

Fermentation optimization, characterization and bioactivity of exopolysaccharides from Funalia trogii.

Optimization of culture conditions for exopolysaccharide (EPS) by Funalia trogii in submerged culture was investigated using one-factor-at-a-time method and uniform design (UD). Under the optimized conditions, the maximum concentration of EPS was 8.68 g/l. After EPS was deproteinized by Sevag method, two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by gel filtration chromatography on Sepharose CL-6B. Furthermore, EPSs were characterized by size exclusion chromatography (SEC) coupled with a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar masses of the Fr-I and Fr-II were determined to be 1.007 × 10(5) and 2.393 × 10(4)g/mol, respectively. The root mean square (RMS) radii for both peaks ranged from 9.7 to 10.8 nm with no clear trends. Pharmacology experiments indicated F. trogii EPS were useful to the therapy of free radical injury and cancer diseases.