Inhibition of phospholipase A<Subscript>2</Subscript> activity by conjugated linoleic acids in human macrophages

The objective of this study was to assess the effect of conjugated linoleic acid isomers (CLAs) on the expression and activity of phospholipases A₂ (PLA₂) in human macrophages. Macrophages were incubated with 30 μM cis-9, trans-11 and trans-10, cis-12 CLAs for 48 h. After incubation, the total activity of phospholipases as well as the expression of mRNA for cytosolic (cPLA₂) and secretory (sPLA₂) phospholipases and activity of sPLA₂ were measured. Both CLA isomers reduced the total activity of PLA₂ (by 30.2%, P < 0.01 for cis-9, trans-11 CLA and by 30%, P < 0.001 for trans-10, cis-12 CLA). Trans-10, cis-12 CLA isomer downregulated the expression of mRNA of sPLA₂ and decreased the enzymatic activity of this enzyme (by 23%, P = 0.02) in macrophages. Conjugated linoleic acid isomers can significantly reduce the activity of PLA₂ in macrophages and downregulate sPLA₂ expression. The consequence of this effect may be reduction of releasing the arachidonic acid (AA) from the cellular membranes of macrophages. Supported by grant No. 3 P05B 117 23 from the State Committee for Scientific Research, Poland.     

脂蛋白残粒RLP-C的检测与临床意义

Triglyceride - rich hpoprotein (TRL) remnants have been imphcated by both clinical and laboratory studies in the pathogenesis of atheroselerosis and thrombosis. We use an new immunoseparation method, provided by Japan Immunoresearch Laboratories, to determine the remnant - hke particles(RLP) of hpeproteins. Isolation of RLP from serum is achieved using an immunoaffmity gel containing specific anti - human apoA- I and apoB- 100 (JI - H) monoelonal antibodies, where the former recognizes HDL and newly secreted apoA - I - containing chylomicrons, the latter recognizes LDL and majority of VLDL. As a result of the specificity of the JI - H antibody, the majority of the apoB - 48 - containing chylomicrons, and certain apoE - enriched apoB - 100 - containing VLDL axe not recognized. These lipoproteins are not captured by the immunoaffinity gel and are thus isolated in the unbound RLP fraction,which is predominantly made up of TRL having remnant - hke properties. The components of the unbounded fraction axe the remnants of CM and VLDLs, verified by ultracentrifugation and lipoproteins electrophoresis in agarose gels. We established a convenient approach to measure RLP- cholesterol on the Hitachi 7150 biochemical analyser.The within- run and run - to- run imprecision (CV) of the assay was 2.75% and 11.48% respectively. The linear of the RLP- c in our assay was 0 - 180 mg/dl. We chose 30 normal lipids level for the control group ( 15 male & 15 female), the median fasting serum RLP - c concentration was 8.12 ± 4.88 mg/dl. We fred that RLP - c concentration were signficantly correlated with TG, VLDL - c, HDL -c & apoE( r = 0.765,0.511, - 0. 378,0.241 respectively, P < 0.01 ) ; and no signficant correlation was subsequently observed between RLP- c and LDL- c. In our study, the median fasting RLP- c concentration were significantly higher in 91 patients with coronary artery disease (CAD),in 15 patients with non- insulin dependent diabetes meUitus (DM),and in 45 patients undergoing hemodialysis with end - stage retinal diseases than in 30 controls, the median ±SD were 27.61 ± 13.20 mg/dl, 16.64 ± 10.32mg/dl, 24.39 ± 13.87mg/dl vs 8.12 ± 4.88mg/dl( P <0.01). In the hypemiglyceride level of the CAD patients,25 over 46 (54.3%) have severe coronary artery lesions,and 19 over 27(70.4% ) in the normal TG level of the CAD patients as well. We only find significant difference of age and HDL - c ( P = 0. 044, n = 73), but not RLP - c, TC, TG, LDL - c, be-tween the CAD patients with mild and severe coronary artery lesions, which confirmed by angiography;even between the normal TG level of CAD patients with such degree of lesions, only HDL - c ( P = 0.012, n = 27) showed a significant difference. For the retinal diseases patients undergoing hemodialysis, we find the tendency of RLP- c increasing and HLD - c decreasing according to the time of hemodialysis. In conclusion, RLP - c level is strongly associated with CAD & DM independent of LDL - c, and associated with coronary artery lesions in the CAD patients with normal triglycerides. It can be a new lipid parameter to evaluate the hemodialysis.     

Contaminant Loading in Drainage and Fresh Water Used for Wetland Management at Stillwater National Wildlife Refuge

Throughout the western United States, studies have identified various detrimental effects of contaminants to aquatic biota from the use of agricultural drainage water for management of arid wetlands. However, little is known about the relative contributions of contaminant loading from pollutants dissolved in water compared with those carried by drifting material (e.g., detritus) associated with drainage water. Consequently, we determined loading rates for contaminants dissolved in water and those incorporated by drifting material for drainage (Diagonal Drain) as well as fresh (S-Line Canal) water used for wetland management at Stillwater National Wildlife Refuge (SNWR), Nevada during the early, middle, and late periods of the irrigation season (June through mid-November) in 1993. We found loading rates for trace elements throughout the irrigation season were almost entirely (> 98%) associated with contaminants dissolved in the water rather than incorporated by drift. Although drift contributed little to the total loading for trace elements to SNWR wetlands, contaminant concentrations were much greater in drift compared with those dissolved in water. Loading rates for dissolved As, B, Hg, and total dissolved solids (TDS) differed among periods for the Diagonal Drain. Along the Diagonal Drain, loading rates for dissolved As, B, Hg, Mo, unionized ammonia (NH₃-N), TDS, and Zn differed among its three sampling sites. B was the only trace element with differences in loading rates for drift among periods from the Diagonal Drain. In contrast, loading rates for As, B, Cr, Cu, Hg, Se, and Zn in drift differed among periods for the S-Line Canal. Along Diagonal Drain, loading rates in drift for B (middle and late periods), Cr, Cu, and Zn differed among sites. Hg (xˉ ≥ 12.0 ng/L) and NH₃-N (xˉ ≥ 0.985 mg/L) dissolved in water as well as B (xˉ ≥ 97.4 μg/g DW) and Hg (xˉ ≥ 0.461 μg/g DW) in drift from the Diagonal Drain and S-Line Canal exceeded screening levels (SLs) for protection of aquatic biota throughout the irrigation season. Dissolved As (xˉ ≥ 0.0426 mg/L) in water from the Diagonal Drain during all periods exceeded the SL for protection of aquatic biota. Dissolved B (xˉ = 1.03 mg/L) in water from the Diagonal Drain during the early period exceeded the SL for protection of aquatic biota. Received: 18 September 1997/Accepted: 5 February 1998     

Flavonoids inhibit the formation of the cross-linking AGE pentosidine in collagen incubated with glucose,according to their structure

Summary Background Glycoxidation of collagens contributes to development of vascular complications in diabetes. Aim of the study Since flavonoids are potent antioxidants present in vegetal foods, it was interesting to examine their effect on the formation of a cross-linking advanced glycation endproduct, pentosidine, in collagens. Methods Collagen was incubated with glucose (250 mM), in the presence of different flavonoids. Pentosidine was measured by HPLC, hydroxyproline colorimetrically. Results Monomeric flavonoids (25 and 250 μM) markedly reduced pentosidine/hydroxyproline values in a concentration- and structure-dependent manner. In decreasing order of their specific inhibitory activity, they rank as follows: myricetin ≥ quercetin > rutin > (+)catechin > kaempferol. Thus 3′-OH or 4-oxo + Delta_2–3 increase the inhibitory activity; conjugation by Rha-Glc on 3-OH decreases it. Procyanidin oligomers from grape seed were more active than pine bark procyanidin oligomers: this may be related to the galloyl residues present in grape seed oligomers only. Procyanidin oligomers are known to be cleaved into monomers in the gastric milieu and monomeric flavonoids to be absorbed and recovered at micromolar concentrations (with a long plasmatic half-life) in extracellular fluids, in contact with collagens. Conclusion Flavonoids are very potent inhibitors of pentosidine formation in collagens. They are active at micromolar concentrations; these might be achieved in plasma of diabetic patients after oral intake of natural flavonoids.     

Chub (Leuciscus cephalus) as a Bioindicator of Contamination of the Vltava River by Synthetic Musk Fragrances

Synthetic musk fragrances, which are contained in almost all scented consumer products, enter aquatic environment mainly by way of wastewater paths. To monitor contamination of the Vltava River by these relatively persistent chemicals in the surroundings of Prague industrialized agglomeration, chub (Leuciscus cephalus) was employed as a bioindicator. Validated gas chromatography–mass spectrometry method was used for fish sample examination. Polycyclic musks, represented by 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-(γ)-2-benzopyran (galaxolide) and 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)-ethanone (tonalide) were the most abundant representatives of this group; their levels in fillets were in the range of 1.7 to 105.9 μg/kg and 0.9 to 19.3 μg/kg wet weight, respectively. Nitro-musks, musk ketone, and musk xylene were also detected in most samples; nevertheless, their levels were lower, ≤2 μg/kg. Significant contamination of resident fish was recognised in the locality of Klecany, which is located 6 km downstream from a large municipal sewage-treatment plant (STP). High levels of musks found in the locality of Vraňany, 32 km downstream from Prague STP, were caused not only by this emission source but probably also by the effluents from the local plant that produces cleaning agents in Velvary.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

丹参注射液与异甘草酸镁抗肝纤维化的临床对比研究

Objective To observe the change of liver function and liver fibrosis indexes of the chronic hepatitis B patients that were treated by Danshen injection(DI) and magnesium isnglyeyrrhizinate(MI). Methods 80 chronic hepati-tis B patients based on the conventional treatment were randomly divided into D1 group(40 patients) and MI group(40 pa-tients). The two groups were used with DI and MI injection for 30 days respaetively and then,the levels of liver function and serum hepatic fibrosis(HA, LN, Ⅳ -C) were detected and compared before and after treatment. Results Treatment by DI and MI could both improve liver function significantly, the effect of Ml group was better than DI group(P < 0.05). Moreover, in improving serum hepatic fibrosis, the effect of DI group was better than MI group (P < 0.05). Conclusions The efficacy of the improvement to hepatic fibrosis DI is better than MI, while in improvement of liver function MI is superior to DI.     

Modulation of folate uptake in cultured human colon adenocarcinoma Caco-2 cells by dietary compounds

Folate is a water-soluble B vitamin with a crucial role in the synthesis and methylation of DNA and in the metabolism of several amino acids. In the present study we investigated whether beverages like wine, beer and tea, or some of their specific constituents, affect the intestinal uptake of ³H-folic acid or ³H-methotrexate (an antifolate). All tested beverages significantly inhibited the uptake of ³H-folic acid by Caco-2 cells. Most of these beverages, with the exception of wines (not tested), also inhibited ³H-methotrexate uptake in these cells. Additionally, ethanol, when tested separately, inhibited the uptake of both compounds. Some of the tested phenolic compounds, namely myricetin, epigallocatechin gallate (EGCG) and isoxanthohumol, markedly inhibited ³H-folic acid uptake. Myricetin and EGCG also had a concentration-dependent inhibitory effect upon the uptake of ³H-methotrexate by Caco-2 cells. Resveratrol, quercetin and kaempferol were able to inhibit the transport of both compounds, but only in the concentration of 100 μM. In conclusion, dietary constituents may impact on intestinal folate uptake, as here shown for phenolic compounds.     

The dispersion state of milk fat influences triglyceride metabolism in the rat

Summary Background Milk fat, which has different structures in the various dairy products, is a major and controversial lipid source in the Western diet. However, information about the digestion fate of milk fat depending on its supramolecular structure for a given composition is scarce. Aim of the study In this study, ¹³CO₂ breath tests were performed with fasted rats force–fed different dairy preparations of similar composition but differing in fat suprastructure in order to highlight differences of general lipid metabolism. Methods Each preparation consisted of a NaCl solution, anhydrous milk fat labelled with a ¹³C mixed triacylglycerol, casein (as native phosphocaseinate powder with some lactose), and dipalmitoylphosphatidylcholine. Milk fat was either fed (i) unemulsified consecutively to the aqueous phase, or emulsified as (ii) coarse droplets of ∼10 μm covered mainly with the phospholipid, or (iii–iv) fine droplets of ∼1 μm covered mainly with casein, force–fed either in the liquid state or in a semi–crystallized state. ¹³C abundance in expired air samples was measured by isotope ratio mass spectrometry; results were expressed as ¹³C enrichment and were submitted to an ANOVA analysis. Results The ¹³CO₂ excretion curves of the unemulsified preparation and the coarse emulsion were similar and presented a sharp peak, both significantly different from the fine emulsion curves characterized by a nearly linear cumulative recovery. The crystalline state of the fine emulsion droplets and the viscosity of these emulsions did not affect significantly their excretion curves. The lipid metabolization (indicated by the ¹³C recovery) was significantly slower for the fine droplets coated with casein than for the large droplets coated with the phospholipid and the unemulsified fat. For the latter, a single ¹³C peak rapidly appeared, while for small droplets coated with caseins, ¹³C excretion was continuous up to 6 h. Conclusions Global lipid metabolism based on oxidation to CO₂ was decreased with smaller compared to larger emulsified milk fat particles with different coatings. These data support the concept that dairy products with different fat suprastructures are digested and metabolized differently.     

Role of Toll-like receptor 4 in intestinal ischemia-reperfusion and the interventional role of ω-3 polyunsaturated fatty acids

Toll-like receptors is a super-family of pathogen recognition-receptors discovered in recent years.During the process of ischemia-reperfusion, the Toll-like receptor 4 (TLR4) combines with lipopolysaccharide and many endogenous ligands such as high mobility group protein B1, heparan sulfate, and fibrinogen. Through the myeloid differentiation protein 88 -dependent and -independent signaling pathways, the products induce the release of inflammatory cytokine-mediated inflammatory response, leading to injuries. ω-3 polyunsaturated fatty acids, by inhibiting the signal pathway activation and target gene expression of TLR4, can influence the function of many immune cells and regulate the body's inflammatory response and immune function. This article reviews the function of TLR4 during ischemia-reperfusion injury and the possible interventional role of ω-3 polyunsaturated fatty acids.     

拉米夫定联合还原型谷胱甘肽预防乙型肝炎病毒携带者抗结核的肝损害研究

Objective To explore the preventive effect of liver damage treated by lamivadine joint reduced glutathione for the tuberculosis patients with HBV infection. Methods 90 cases of tuberculosis patients with HBV infection were randomly divided into three groups (A, B, C), each group contained 30 cases. Patients in group A were treated by lamivudine combined with reduced glutathione to protect the liver before anti-tuberculosis treatment. Group B were treated with reduced glutathione. Group C were treated with Yiganling tablets. Both the liver function and serum HBV DNA levels before anti-tuberculosis treatment and 1 month and 2 months after treatment were observed and recorded. Results The cases of liver damage in group A, B, C were 1, 12, 18 respectively, there were statistical differences between group A and group B, group C (χ2 = 11.882, 22.259, P < 0.01). The cases of discontinued treatment due to different causes in group A,B,C were 0,4,11 respectively, there were statistical differences between group A and group B,group C(χ2 = 4.286, P < 0.05; χ2 = 13.469, P < 0.01). The cases of discontinue treatment in the no antivirus group were much more than the antivirus group. There were also statistical differences in both liver damage and discontinued treatment between group B and group C(χ2 = 5.455,4.356, P < 0.05). There was no statistical difference of baseline HBV DNA level between group A and group B (P > 0.05), and also no statistical difference between group A and group C ( P > 0.05), but there were statistical differences in HBV DNA level between group A and group B, as well as group A and group C after 1-month and 2-month therapy( t = - 6.542, - 6.746 and t = - 9.358, - 10.085, P < 0.01). Conclusions Tuberculosis patients coinfected with HBV can use reduced glutathione to prevent liver damage while antitubercular therapy, and simultaneous application of lamivudine therapy can restrain HBV replication and improve the prognosis obviously.     

Role of cAMP in Tissues of Mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> As a Potent Biomarker of Cadmium in Marine Environments

Pesticides with chlorpyrifos and endosulfan as active element are used for pest control on agricultural lands and are high-risk inputs in aquatic systems. The acute toxicity of these insecticides in the freshwater prawn Palaemonetes argentinus was evaluated. The results were used to determine the lowest observed–effect and no observed–effect concentrations. Individual growth of prawns in relation to chlorpyrifos and endosulfan exposure was analyzed. LC₅₀ values to chlorpyrifos and endosulfan exposure were 2.98 μg L^–1 and 14.10 at 24 hours and 0.49 μg L^–1 and 6.28 μg L^–1 at 96 hours of exposure, respectively. The size increment of prawns was the same in all treatments; cephalothorax length increased linearly per molt. The intermolt period was influenced by the toxic effect of pesticides during rearing time, and this decreased with the molt cycles compared with the normal growth pattern. The results suggest that juveniles of P. argentinus are sensitive to chlorpyrifos and endosulfan pollution.     

Influence of quercetin and rutin on growth and antioxidant defense system of a human hepatoma cell line (HepG2)

Summary Background Dietary polyphenols like quercetin and rutin are considered beneficial because of their potential protective role in the pathogenesis of multiple diseases associated to oxidative stress such as cancer, coronary heart disease and atherosclerosis. However, many of these effects may depend on the concentration of the polyphenol utilized since high doses of some phenolic compounds may be prooxidant and negatively affect cell growth and viability. Aim of the study To test the potential chemoprotective effects of quercetin and rutin, two flavonols with high antioxidant capacity, on cell growth, viability and the response of the antioxidant defense system of a human hepatoma cell line (HepG2). Methods Cell growth was measured by diaminobenzoic acid and bromodeoxyuridine assays, cell toxicity by lactate dehydrogenase leakage assay, reduced glutathione was quantified by a fluorimetric assay, cellular malondialdehyde was analyzed by high–performance liquid chromatography, reactive oxygen species were quantified by the dichlorofluorescein assay, antioxidant enzyme activities were determined by spectrophotometric analysis and their gene expression by northern blot. Results Short-term exposure (4 h) to these flavonols had no antiproliferative nor cytotoxic effect. High doses of quercetin (50–100 μM) increased glutathione concentration and gene expression of Cu/Zn superoxide dismutase and catalase inhibiting the activity of the latter enzyme, whereas lower doses (0.1–1 μM) decreased gene expression of Cu/Zn superoxide dismutase and increased that of glutathione peroxidase. All doses of quercetin and rutin diminished reactive oxygen species and high doses (10–100 μM) decreased malondialdehyde concentration. Conclusion The results indicate that both natural antioxidants induce favorable changes in the antioxidant defense system of cultured HepG2 that prevent or delay conditions which favor cellular oxidative stress.