Generation of reactive oxygen species mediated by humic-like substances in atmospheric aerosols

Particulate matter (PM)-mediated reactive oxygen species (ROS) generation has been implicated in health effects posed by PM. Humic-like substances (HULIS) are an unresolved mixture of water-extracted organic compounds from atmospheric aerosol particles or isolated from fog/cloudwater samples. In this study, we use a cell-free dithiothreitol (DTT) assay to measure ROS production mediated by HULIS. The HULIS samples are isolated from aerosols collected at a rural location and a suburban location in the Pearl River Delta, China. In our experiments, ROS activities by residue metal ions in the HULIS fraction are suppressed by including a strong chelating agent in the DTT assay. Under conditions of DTT consumption not exceeding 90%, the HULIS-catalyzed oxidation of DTT follows the zero-order kinetics with respect to DTT concentration, and the rate of DTT oxidation is proportional to the dose of HULIS. The ROS activity of the aerosol HULIS, on a per unit mass basis is 2% of the ROS activity by a reference quinone compound, 1,4-naphthoquinone and exceeds that of two aquatic fulvic acids. The HULIS fraction in the ambient samples tested exhibits comparable ROS activities to the organic solvent extractable fraction, which would contain compounds such as quinones, a known organic compound class capable of catalyzing generation of ROS in cells. HULIS was found to be the major redox active constituent of the water-extractable organic fraction in PM. It is plausible that HULIS contains reversible redox sites, thereby serving as electron carriers to catalyze the formation of ROS. Our work suggests that HULIS could be an active PM component in generating ROS and further work is warranted to characterize its redox properties.     

Quinone emissions from gasoline and diesel motor vehicles

Gas- and particle-phase emissions from gasoline and diesel vehicles operated on chassis dynamometers were collected using annular denuders, quartz filters, and PUF substrates. Quinone species were measured using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization in conjunction with gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry. Nine quinones were observed, ranging from C6 to C16. New species identified in motor vehicle exhaust include methyl-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone (MNQN), and aceanthrenequinone. Gas-phase motor vehicle emissions of quinones are also reported for the first time. Six gas-phase quinones were quantified with emission rates of 2-28 000 microg L(-1) fuel consumed. The most abundant gas-phase quinones were 1,4-benzoquinone (BON) and MNQN. The gas-phase fraction was > or = 69% of quinone mass for light-duty gasoline emissions, and > or = 84% for heavy-duty diesel emissions. Eight particle-phase quinones were observed between 2 and 1600 microg L(-1), with BQN the most abundant species followed by 9,10-phenanthrenequinone and 1,2-naphthoquinone. Current particle-phase quinone measurements agree well with the few available previous results. Further research is needed concerning the gas-particle partitioning behavior of quinones in ambient and combustion source conditions.     

Development and application of an electron spin resonance spectrometry method for the determination of oxygen free radical formation by particulate matter

Exposure to increased levels of ambient particulate matter (PM) are associated with several health effects, including cardiopulmonary diseases. The formation of reactive oxygen species (ROS) is thought to play an important role in the induction of these health effects. To quantify the ROS generating capacityof PM,we developed an improved electron spin resonance (ESR) spectrometry-based method. ROS formation was measured directly on PM-containing filters, thereby avoiding the selective extraction of components and loss of material or reactivity, which is likely to occur during filter extraction. Also, ascorbic acid was added to stimulate ROS formation. This method was applied to PM10 samples originating from different sources. The radical generating capacity of PM10 from both gasoline and diesel engine exhaust was significantly higher as compared to that of PM10 from ambient or indoor air. Furthermore, in urban PM10 and PM2.5, ROS-generating capacity significantly correlated with concentrations of polycyclic aromatic hydrocarbon content and particular transition metals. This indicates thatthis improved ESR method may be a valuable tool for evaluating the relationship between ROS formation by PM and the adverse health effects associated with this type of air pollution.     

ACE-Asia intercomparison of a thermal-optical method for the determination of particle-phase organic and elemental carbon

A laboratory intercomparison of organic carbon (OC) and elemental carbon (EC) measurements of atmospheric particulate matter samples collected on quartz filters was conducted among eight participants of the ACE-Asia field experiment The intercomparison took place in two stages: the first round of the intercomparison was conducted when filter samples collected during the ACE-Asia experiment were being analyzed for OC and EC, and the second round was conducted after the ACE-Asia experiment and included selected samples from the ACE-Asia experiment Each participant operated ECOC analyzers from the same manufacturer and utilized the same analysis protocol for their measurements. The precision of OC measurements of quartz fiber filters was a function of the filter's carbon loading but was found to be in the range of 4-13% for OC loadings of 1.0-25 microg of C cm(-2). For measurements of EC, the precision was found to be in the range of 6-21% for EC loadings in the range of 0.7-8.4 microg of C cm(-2). It was demonstrated for three ambient samples, four source samples, and three complex mixtures of organic compounds that the relative amount of total evolved carbon allocated as OC and EC (i.e., the ECOC split) is sensitive to the temperature program used for analysis, and the magnitude of the sensitivity is dependent on the types of aerosol particles collected. The fraction of elemental carbon measured in wood smoke and an extract of organic compounds from a wood smoke sample were sensitive to the temperature program used for the ECOC analysis. The ECOC split for the three ambient samples and a coal fly ash sample showed moderate sensitivity to temperature program, while a carbon black sample and a sample of secondary organic aerosol were measured to have the same split of OC and EC with all temperature programs that were examined.     

Diurnal trends in oxidative potential of coarse particulate matter in the Los Angeles Basin and their relation to sources and chemical composition

To investigate the relationship among sources, chemical composition, and redox activity of coarse particulate matter (CPM), three sampling sites were set up up in the Los Angeles Basin to collect ambient coarse particles at four time periods (morning, midday, afternoon, and overnight) in summer 2009 and winter 2010. The generation of reactive oxygen species (ROS) was used to assess the redox activity of these particles. Our results present distinct diurnal profiles of CPM-induced ROS formation in the two seasons, with much higher levels in summer than winter. Higher ROS activity was observed in the midday/afternoon during summertime, while the peak activity occurred in the overnight period in winter. Crustal materials, the major component of CPM, demonstrated very low water-solubility, in contrast with the modestly water-soluble anthropogenic metals, including Ba and Cu. The water-soluble fraction of four elements (V, Pd, Cu, and Rh) with primary anthropogenic origins displayed the highest associations with ROS activity (R(2) > 0.60). Our results show that coarse particles generated by anthropogenic activities, despite their low contribution to CPM mass, are important to the biological activity of CPM, and that a more targeted control strategy may be needed to protect the public health from these toxic CPM sources.     

Evidence for the existence of organosulfates from beta-pinene ozonolysis in ambient secondary organic aerosol

The formation of organosulfates from the gas-phase ozonolysis of beta-pinene in the presence of neutral or acidic sulfate particles was investigated in a series of indoor aerosol chamber experiments. The organosulfates were analyzed using high-performance liquid chromatography (LC) coupled to electrospray ionization-time-of-flight mass spectrometry (MS) in parallel to ion trap MS. Organosulfates were only found in secondary organic aerosol from beta-pinene ozonolysis in the presence of acidic sulfate seed particles. One of the detected organosulfates also occurred in ambient aerosol samples that were collected at a forest site in northeastern Bavaria, Germany. beta-Pinene oxide, an oxidation product in beta-pinene/O3 and beta-pinene/NO3 reactions, is identified as a possible precursor for the beta-pinene-derived organosulfate. Furthermore, several nitroxy-organosulfates originating from monoterpenes were found in the ambient samples. These nitroxy-organosulfates were only detected in the nighttime samples, suggesting a role for nighttime chemistry in their formation. Their LC/MS chromatographic peak intensities suggest that they represent an important fraction of the organic mass in ambient aerosols, especially at night.     

Chemical investigation of eight different types of carbonaceous particles using thermoanalytical techniques

The chemical composition of ambient aerosol particles affects numerous important aerosol parameters such as their hygroscopicity, optics, and mass as well as their potentially adverse health effects. The objective of this study was to derive both detailed chemical speciation and useful proxies for the quantitative classification of the organic matter (OM) content of carbonaceous aerosol samples. Using three different thermal desorption techniques in an inert atmosphere we investigated eight different carbonaceous particulate matter (PM) samples used for health effect studies: thermal desorption gas chromatography with mass spectrometry, evolved gas analysis with mass spectrometry, and thermogravimetry with Fourier transform infrared spectroscopy. The samples include different types of laboratory-generated particles (pigment black, diffusion flame soot, spark-generated carbon) and two ambient aerosol samples (diesel soot and particulates collected in a road tunnel). All samples showed increasing mass desorption with rising temperature, but no reliable OM classification was possible based on thermal mass desorption alone. In fact, the "organic-free" spark-generated carbon particles showed the second highest mass desorption at 800 degrees C due to the formation of oxygenated structures on unsaturated surface sites and the subsequent evolution of CO and CO2 at elevated temperatures. A quantitative OM classification was accomplished by combining measurements of thermogravimetry and mass spectrometry (up to 800 degrees C) into a novel parameter, the "apparent organic mass fraction". The validity of this classification was confirmed with a second proxy parameter, based only on the evolution of organic components during thermal desorption and information on the generation process of the particles. Both types of pigment blacks (Printex) samples and the spark-generated carbon particles showed the lowest apparent organic mass fraction (< 5%), whereas for road tunnel and diesel emission particles < 16 and < 19% was estimated, respectively.     

Mechanism for the effect of agitation on the molecular weight of hyaluronic acid produced by Streptococcus zooepidemicus

Various views persist about the effect of agitation on hyaluronic acid (HA) molecular weight, and the mechanism remains unclear. In this paper, the effect of agitation on HA molecular weight was investigated. The HA molecular weight increased with impeller speed, due to a mass transfer enhancement; however, higher impeller speed caused a decrease in the HA molecular weight. According to the experimental results, it is proposed for the first time that reactive oxygen species (ROS) under higher impeller speed in the bioreactor, which were generated by NADH oxidase, could cause the reduction in the HA molecular weight. ROS generation increased remarkably during the exponential growth phase when the impeller speed increased from 450 rpm to 1000 rpm, and the NADH oxidase activity increased correspondingly. Finally, it was proved that the addition of salicylic acid could increase the HA molecular weight, but inhibit the efficiency of the HA synthesis.     

Characterization of saccharides in size-fractionated ambient particulate matter and aerosol sources: the contribution of primary biological aerosol particles (PBAPs) and soil to ambient particulate matter

Size-fractionated (equivalent to ambient PM2.5 and PM10) local soil, plant, and spore samples were collected in the Sonoran Desert near Phoenix, AZ and measured for saccharide content with the goal of characterizing ambient particulate matter sources including soil and primary biological aerosol particles (PBAPs) from plants and fungi. Different saccharide compositions were observed among soil, plant, and spore samples and between PM2.5 and PM10 fractions. The total measured nonlevoglucosan saccharide content relative to PM mass in ambient aerosols collected in a Phoenix suburb (Higley) was much higher compared to the local soil samples but much lower compared to the PBAP. The enrichment of saccharides from two saccharide-dominated PM source factors resolved by a positive matrix factorization model is also higher than the saccharide content in the size-fractionated local soil samples, but lower than that measured in the size-segregated PBAP samples. This indicates that ambient concentration of particulate saccharides at Higley was dominated by contributions from PBAPs directly injected into the atmosphere from plants and spores rather than from soil and associated biota. Our results also suggest the contribution to the fine size fraction of ambient PM from the primary biologically derived sources may be greater than previously acknowledged.     

Secondary organic aerosol from ozonolysis of biogenic volatile organic compounds: chamber studies of particle and reactive oxygen species formation

The formation of secondary organic aerosol (SOA) produced from α-pinene, linalool, and limonene by ozonolysis was examined using a dynamic chamber system that allowed the simulation of ventilated indoor environments. Experiments were conducted at typical room temperatures and air exchange rates. Limonene ozonolysis produced the highest SOA mass concentrations and linalool the lowest with α-pinene being intermediate. Simplified empirical modeling simulations were conducted to provide insights into reaction chemistry. Assessment of variability of particle-bound reactive oxygen species (ROS) may be important in the understanding of health effects associated with particulate matter. The ROS intensities defined as ROS/SOA mass were found to be moderately correlated with the SOA densities. Greater ROS intensities were observed for the cases where ozone was in excess. ROS intensities approached a relatively constant value in the region where ozone was in deficit. The estimated initial ROS half-life time was approximately 6.5 h at room temperature suggesting the time sensitivity of ROS measurements. The ROS formed from terpenoid ozonolysis could be separated into three categories: short-lived/high reactive/volatile, semivolatile/relatively stable and nonvolatile/low reactive species based on ROS measurements under various conditions. Such physical characterization of the ROS in terms of reactivity and volatility provides some insights into the nature of ROS.     

Stressed salmonella are exposed to reactive oxygen species from two independent sources during recovery in conventional culture media

Previously, Stephens et al. [J. Appl. Microbiol. 83 (1997) 445–455] developed a sensitive technique for studying the resuscitation of low levels of stressed Salmonella. Using this technique the influence on recovery performance of the peptone component of buffered peptone water was investigated. Within 12 different peptone types as much as 3.5 log₁₀ cells/ml difference was observed between the best and worst performing formulations. Poor recovery performance was linked to reactive oxygen species (ROS) generation through auto-oxidation of reducing sugars and photo-sensitisation of sensitive components such as riboflavin. Supplementary recovery agents were explored with only Oxyrase^®, which has both enzymes to degrade ROS and the ability to rapidly turn a medium anaerobic, having any significant effect. It improved the speed of recovery and increased, by up to 100-fold, the number of stressed cells recovered. Stressed cells were further studied by flow cytometry with cell sorting, based on the staining pattern from a novel fluorochrome combination, into good and poor recovery media. It was identified that within a stressed population the removal of all oxygen protected actively respiring cells the most by forcing them to generate energy from anaerobic metabolism thus avoiding any risk from accidental endogenous ROS generation. The recognition of two independent sources of oxidative stress in the routine use of conventional culture media is discussed in relation to pathogen detection and other areas of food microbiology.     

Ambient particulate matter exhibits direct inhibitory effects on oxidative stress enzymes

A primary mechanistic hypothesis by which ambient air particles have a significant negative impact on human health is via the induction of pulmonary inflammatory responses mediated through the generation of reactive oxygen species (ROS). Development of a biosensor for the assessment of particulate ROS activity would be a significant advance in air pollution monitoring. The objective of this study was to evaluate whether air particulates interact directly with protective enzymes involved in oxidative stress responses. We performed enzyme activity assays on four enzymes involved in oxidative stress responses (Cu/Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, and glutathione reductase) in the presence of particles of varying toxicities and found distinctive inhibition patterns. On the basis of these findings, we suggest a strategy for an enzyme bioassay that could be used to assess the potential of particles to generate ROS-induced responses.     

Effects of in vitro insulin and 2,4-thiazolidinedione on the function of neutrophils harvested from blood of cows in different physiological states

Neutrophils [polymorphonuclear neutrophilic leukocytes (PMNL)] were isolated from 26 Holstein cows in different physiological states (12 ± 1.7 d prepartum, n = 8; 7 ± 0 d postpartum, n = 9; 253 ± 25.2 d postpartum, n = 9) and incubated in vitro for 120 min in a factorial arrangement of treatments with 0, 1.5, or 15 ng/mL of bovine insulin and 0 or 300 μg/mL of the peroxisome proliferator-activated receptor-γ ligand 2,4-thiazolidinedione (TZD). Following the incubations, PMNL functional assays were performed to determine treatment effects on proxies for total, extracellular, and intracellular generation of reactive oxygen species (ROS), neutrophil extracellular trap formation, and phagocytic killing abilities. The ROS production of PMNL collected from cows at 7 d postpartum was reduced compared with that of PMNL from midlactation and prepartum cows, but neutrophil extracellular trap expression was 23 and 36% greater in PMNL from prepartum cows compared with that in PMNL from midlactation and postpartum cows, respectively. Insulin had no effect on PMNL functional assay results. In contrast, TZD inhibited a measurement of total ROS production by 89%, increased extracellular superoxide generation by 43%, but had no effect on the intracellular ROS measured. Interestingly, TZD did not alter the ability of the PMNL to release neutrophil extracellular traps and engulf or kill Staphylococcus aureus. These findings suggest a possible anti-inflammatory effect of TZD that may result in reduced extracellular oxidative damage with maintenance of PMNL antimicrobial activity.     

Stressed Salmonella are exposed to reactive oxygen species from two independent sources during recovery in conventional culture media

Previously, Stephens et al. [J. Appl. Microbiol. 83 (1997) 445–455] developed a sensitive technique for studying the resuscitation of low levels of stressed Salmonella. Using this technique the influence on recovery performance of the peptone component of buffered peptone water was investigated. Within 12 different peptone types as much as 3.5 log₁₀ cells/ml difference was observed between the best and worst performing formulations. Poor recovery performance was linked to reactive oxygen species (ROS) generation through auto-oxidation of reducing sugars and photo-sensitisation of sensitive components such as riboflavin. Supplementary recovery agents were explored with only Oxyrase^®, which has both enzymes to degrade ROS and the ability to rapidly turn a medium anaerobic, having any significant effect. It improved the speed of recovery and increased, by up to 100-fold, the number of stressed cells recovered. Stressed cells were further studied by flow cytometry with cell sorting, based on the staining pattern from a novel fluorochrome combination, into good and poor recovery media. It was identified that within a stressed population the removal of all oxygen protected actively respiring cells the most by forcing them to generate energy from anaerobic metabolism thus avoiding any risk from accidental endogenous ROS generation. The recognition of two independent sources of oxidative stress in the routine use of conventional culture media is discussed in relation to pathogen detection and other areas of food microbiology.     

Oxidative stress, genotoxicity, and vascular cell adhesion molecule expression in cells exposed to particulate matter from combustion of conventional diesel and methyl ester biodiesel blends

Our aim was to compare hazards of particles from combustion of biodiesel blends and conventional diesel (D(100)) in old and improved engines. We determined DNA damage in A549 cells, mRNA levels of CCL2 and IL8 in THP-1 cells, and expression of ICAM-1 and VCAM-1 in human umbilical cord endothelial cells (HUVECs). Viability and production of reactive oxygen species (ROS) were investigated in all cell types. We collected particles from combustion of D(100) and 20% (w/w) blends of animal fat or rapeseed oil methyl esters in light-duty vehicle engines complying with Euro2 or Euro4 standards. Particles emitted from the Euro4 engine were smaller in size and more potent than particles emitted from the Euro2 engine with respect to ROS production and DNA damage, but similarly potent concerning cytokine mRNA expression. Particles emitted from combustion of biodiesel blends were larger in size, and less or equally potent than particles emitted from combustion of D(100) concerning ROS production, DNA damage and mRNA of CCL2 and IL8. ICAM-1 and VCAM-1 expression in HUVECs was only increased by D(100) particles from the Euro4 engine. This suggests that particle emissions from biodiesel in equal mass concentration are less toxic than conventional diesel.     

Determination of methoxyphenols in ambient atmospheric particulate matter: tracers for wood combustion

Combustion of wood and other biomass fuels produces source-specific organic compounds arising from pyrolysis of lignin, including substantial amounts of 4-substituted methoxylated phenolic compounds (methoxyphenols). These compounds have been used as atmospheric markers to determine the contribution of wood smoke to ambient atmospheric fine particulate matter (PM). However, reliable quantification of methoxyphenols represents an analytical challenge because these compounds are polar, semi-volatile, and somewhat reactive. We reportherein an improved gas chromatographic-mass spectrometric (GC/MS) method for the sensitive and reliable determination of methoxyphenols in low-volume ambient PM samples. Deuterated standard compounds are added to the environmental samples prior to extraction to determine analyte recoveries in each sample. Analytical figures of merit for the assay, as applied to ambient PM2.5 and PM10 samples are as follows: recovery = 63-100%; precision = 2-6%; analytical limit of detection (S/N 2) = 0.002 microg/mL; limit of quantitation = 0.07-0.45 ng/m3 (assuming a 14 m3 sample). The improved method was applied to ambient PM samples collected between 1999 and 2000 in Seattle, WA. Particle-bound methoxyphenol concentrations in the range <0.1 to 22 ng/m3 were observed and the methoxyphenols were present almost exclusively in the fine (PM2.5) size fraction. We also demonstrated that XRF analysis of samples of atmospheric PM collected on Teflon filters significantly reduced the levels of methoxyphenols measured in the PM samples in subsequent assay of the same filters. Therefore, XRF analysis of filters, commonly undertaken to obtain trace element concentrations for use in source apportionment analyses, would preclude the subsequent analysis of those filters for methoxyphenols and other similarly semivolatile or reactive organic chemicals.     

Effect of a reactive oxygen species-generating system for control of airborne microorganisms in a meat-processing environment

The effectiveness of reactive oxygen species (ROS)-generating AirOcare equipment on the reduction of airborne bacteria in a meat-processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificially contaminate the air via a six-jet Collison nebulizer. Air in the meat-processing room was sampled immediately after aerosol generation and at various predetermined times at multiple locations by using a Staplex 6 stage air sampler. Approximately a 4-log reduction of the aerial S. marcescens population was observed within 2 h of treatment (P < 0.05) compared to a 1-log reduction in control samples. The S. marcescens populations reduced further by approximately 4.5 log after 24 h of exposure to ROS treatment. Approximately 3-log CFU/m3 reductions in lactic acid bacteria were observed following 2-h ROS exposure. Further ROS exposure reduced lactic acid bacteria in the air; however, the difference in their survival after 24 h of exposure was not significantly different from that observed with the control treatment. S. marcescens bacteria were more sensitive to ROS treatment than the lactic acid bacteria. These findings reveal that ROS treatment using the AirOcare unit significantly reduces airborne S. marcescens and lactic acid bacteria in meat-processing environments within 2 h.     

Antifungal activity of the honey flavonoid extract against Candida albicans

Candida albicans is the most prevalent dimorphic pathogen in humans. We investigated the potential protective effect of honey flavonoid extract (HFE) on Candida dimorphism induced by RPMI 1640 medium. Yeast to hyphal transition was dose dependently prevented when Candida cultures were treated with HFE for 6 h (germ-tube formation) and 18 h (hypha elongation). Since during hyphal growth remarkable amounts of reactive oxygen species (ROS) are generated, we investigated whether HFE affects the generation of ROS, the glutathione level and the activity of glutathione-dependent enzymes. Treatment of Candida cells with 48 μg/ml (MIC₅₀) of HFE for 6 or 18 h inhibited the dimorphic conversion by supporting of the intracellular glutathione level. HFE exerts a dual protective effect inhibiting both ROS generation during germ-tube formation and γ-glutamyltranspeptidase activity, responsible for GSH degradation, during hypha elongation. These results show that HFE confers a significant protection against yeast to hyphal transition of C. albicans.     

Size dependent and reactive oxygen species related nanosilver toxicity to nitrifying bacteria

The intrinsic slow growth of nitrifying bacteria and their high sensitivity to environmental perturbations often result in cell growth inhibition by toxicants. Nanoparticles are of great concern to the environment because of their small size and high catalytic properties. This work sought to determine size-dependent inhibition by Ag nanoparticles and evaluate the relationship between the inhibition and reactive oxygen species (ROS). Nanoparticles with an average size range of 9-21 nm were synthesized by varying the molar ratios of BH4-/Ag+ in the solution. The resulting ROS generation was quantified in the presence and absence of the bacteria while the degree of inhibition was inferred from specific oxygen uptake rate measurements, determined by extant respirometry. By examining the correlation between nanoparticle size distribution, photocatalytic ROS generation, intracellular ROS accumulation, and nitrification inhibition, we observed that inhibition to nitrifying organisms correlated with the fraction of Ag nanoparticles less than 5 nm in the suspension. It appeared that these size nanoparticles could be more toxic to bacteria than any other fractions of nanoparticles or their counterpart bulk species. Furthermore, inhibition by Ag nanoparticles as well as other forms of silver (AgCl colloid and Ag+ ion) correlated well with the intracellular ROS concentrations, but not with the photocatalytic ROS fractions. The ROS correlations were different for the different forms of silver, indicating that factors other than ROS are also important in determining nanosilver toxicity.     

黑灵芝多糖对氧化应激所致心肌细胞损伤的影响

目的：研究黑灵芝多糖(PSG-1)对氧化应激所致大鼠乳鼠心肌细胞损伤的影响。方法：采用过氧化氢(H2O2)作用于心肌细胞,建立氧化应激损伤模型,观察细胞搏动频率,MTT 法测定细胞存活率;比色法测定细胞乳酸脱氢酶(LDH)和超氧化物歧化酶(SOD)的活性及丙二醛(MDA)的含量,流式细胞仪检测细胞内的活性(ROS),蛋白印迹检测细胞SOD 的蛋白表达。结果：PSG-1 预处理可减少MDA 含量,ROS 产生及LDH 的漏出,增加心肌细胞搏动频率、细胞存活率和SOD 活性及蛋白表达并且呈剂量依赖性。结论：PSG-1 对心肌细胞氧化应激损伤具有保护作用,其保护作用可能与降低MDA、ROS 的含量,增强SOD 活性及蛋白的表达有关。