Study on the relationship of genotoxic and oxidative potential of a new mixed chelate copper antitumoral drug,Casiopeina II-gly (Cas II-gly) in Drosophila melanogaster

The present study evaluates the superoxide dismutase (SOD) and catalase (CAT) activities in a wild strain of Drosophila melanogaster and the genotoxic potential induced by Cas II-gly (a new antineoplastic drug) using the somatic mutation and recombination test. Larvae 48 h old were treated with Cas II-gly in a range of 0–1.5 mM and aliquot were taken every 24 h to have individuals treated for 24, 48, 72 h and adulthood as well. A dose-dependent toxicity and a significant increase in SOD and CAT activities were found after a 24 and 48 h treatment with 0.5–1.5 mM concentrations. The comparison of the effect in enzymes with mutation indicated a positive correlation with increased genetic damage, after 24 and 48 h of exposure for all concentrations tested. The addition of the genetic damage induced in each exposure time showed a significant effect, but only the small single spots had a concentration-related increase.     

Cytotoxic evaluation of nanostructured zinc oxide (ZnO) thin films and leachates

Nanostructured ZnO films have potential use as coatings on medical devices and food packaging due to their antimicrobial and UV-protection properties. However, their influence on mammalian cells during clinical use is not fully understood. This study investigated the potential cytotoxicity of ZnO thin films in RAW 264.7 macrophages. ZnO thin films (∼96 nm thick with a 50 nm grain) were deposited onto silicon wafers using pulsed laser deposition. Cells grown directly on ZnO thin film coatings exhibited less toxicity than cells exposed to extracts of the coatings. Cells on ZnO thin films exhibited a 43% and 68% decrease in cell viability using the MTT and 7-AAD/Annexin V flow cytometry assays, respectively, after a 24-h exposure as compared to controls. Undiluted 100% 24- and 48-h extracts decreased viability by 89%, increased cell death by LDH release to 76% 24 h after treatment, and increased ROS after 5–24 h of exposure. In contrast, no cytotoxicity or ROS were observed for 25% and 50% extracts, indicating a tolerable concentration. Roughly 24 and 34 μg/m² Zn leached off the surfaces after 24 and 48 h of incubation, respectively. ZnO coatings may produce gradual ion release which becomes toxic after a certain level and should be evaluated using both direct exposure and extraction methods.     

Evaluation of EpiDerm full thickness-300 (EFT-300) as an in vitro model for skin irritation: Studies on aliphatic hydrocarbons

The aim of this study was to understand the skin irritation effects of saturated aliphatic hydrocarbons (HCs), C9–C16, found jet fuels using in vitro 3-dimensional EpiDerm full thickness-300 (EFT-300) skin cultures. The EFT-300 cultures were treated with 2.5 μl of HCs and the culture medium and skin samples were collected at 24 and 48 h to measure the release of various inflammatory biomarkers (IL-1α, IL-6 and IL-8). To validate the in vitro results, in vivo skin irritation studies were carried out in hairless rats by measuring trans epidermal water loss (TEWL) and erythema following un-occlusive dermal exposure of HCs for 72 h. The MTT tissue viability assay results with the EFT-300 tissue show that 2.5 μl/tissue (≈4.1 μl/cm²) of the HCs did not induce any significant changes in the tissue viability for exposure times up to 48 h of exposure. Microscopic observation of the EFT-300 cross-sections indicated that there were no obvious changes in the tissue morphology of the samples at 24 h, but after 48 h of exposure, tridecane, tetradecane and hexadecane produced a slight thickening and disruption of stratum corneum. Dermal exposures of C12–C16 HCs for 24 h significantly increased the expression of IL-1α in the skin as well as in the culture medium. Similarly, dermal exposure of all HCs for 24 h significantly increased the expression of interleukin-6 (IL-6) and IL-8 in the skin as well as in the culture medium in proportion to the HC chain length. As the exposure time increased to 48 h, IL-6 concentrations increased 2-fold compared to the IL-6 values at 24 h. The in vivo skin irritation data also showed that both TEWL and erythema scores increased with increased HCs chain length (C9–C16). In conclusion, the EFT-300 showed that the skin irritation profile of HCs was in the order of C9 ⩽ C10 ⩽ C11 ⩽ C12 < C13 ≈ C14 ≈ C16 and that the tissue was an excellent in vitro model to predict in vivo irritation and to understand the structural activity relationship of HCs.     

The fungicide thiabendazole causes apoptosis in rat hepatocytes

Many pharmaceutical drugs cause hepatotoxicity in humans leading to severe liver diseases, representing a serious public health issue. This study investigates the ability of the anthelmintic and antifungal drug thiabendazole to cause cell death by apoptosis and metabolic changes in primary cultures of rat hepatocytes. Thiabendazole (200–500 μM) induced apoptosis in hepatocytes after 1 to 24 h, causing loss of mitochondrial membrane potential, cytochrome c release from mitochondria, Fas-associated death domain (FADD) translocation from the cytosol to membranes, and activation of caspases-3, -8 and -9. Thus, thiabendazole activated both the mitochondrial and death receptor pathways of apoptosis. Under these conditions, cell death by necrosis was not detected following exposure to thiabendazole (100–500 μM) for 24–48 h, measured by lactate dehydrogenase release and propidium iodide uptake. Furthermore, thiabendazole increased activities of cytochrome P450 (CYP) isoenzymes CYP1A and CYP2B after 24 and 48 h, determined by 7-ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) activities, respectively. An important finding is that thiabendazole can eliminate hepatocytes by apoptosis, which could be a sensitive marker for hepatic damage and cell death. This study improves understanding of the mode of cell death induced by thiabendazole, which is important given that humans and animals are exposed to this compound as a pharmaceutical agent and in an environmental context.     

Acrylamide-induced apoptosis in rat primary astrocytes and human astrocytoma cell lines

This study aimed to evaluate the acrylamide (ACR)-induced apoptotic effects on rat primary astrocytes and three human astrocytoma-derived cell lines (U-1240 MG, U-87 MG, and U-251 MG). As determined through the MTT assay, treatment with 1 and 2 mM ACR for 24–72 h resulted in decreased cell viability in all cells. Decreases in cell viability could be blocked in all cells with the exception of U-251 MG cells by Z-DEVD FMK. ACR-induced dose-dependent apoptotic effects were also demonstrated by increases in the sub-G₁ phase cell population in all cells. The decreased expressions of pro-caspase 3, 8, and 9 and the interruption of the mitochondrial membrane potential were observed in all cells. Exposure to 2 mM ACR for 48 h resulted in increased Bax/Bcl-2 ratios in primary astrocytes and U-87 MG cells, whereas the overexpression of Bcl-2 was observed in U-1240 MG and U-251 MG cells. The ACR-induced increases in the levels of p53 and pp53 in primary astrocytes could be attenuated by caffeine. These results suggest the existence of a common apoptotic pathway among all cell types and that U-87 MG cells may be a suitable substitute in vitro model for primary astrocytes in future studies on ACR-induced neurotoxicity.     

Acrylamide-induced astrogliotic and apoptotic responses in human astrocytoma cells

This study was to clarify whether acrylamide (ACR) will induce apoptosis and astrogliosis in an astrocytic cell line in vitro. Different time- and dose-dependent cytotoxic studies were conducted upon neuronal (SH-SY5Y) and glial cell lines (U-1240 MG) under exposure to ACR up to 72 h. We showed that SH-SY5Y cells were more sensitive in cytotoxic assays than U-1240 MG cells, and significantly decreased cell viability was observed at concentrations higher than 1 mM with increased lactate dehydrogenase leakage observed only at 5 and 10 mM in U-1240 MG cells. The ACR-induced apoptotic responses and phosphorylation of p53 protein at Ser15 for U-1240 MG cells were identified at 48 h. The increase of glial fibrillary acidic protein (GFAP) as a chemical-induced astrogliotic response was found to be associated with different ACR concentrations and exposure times, particularly at ≧48 h of ≧2 mM. In addition, immunocytochemical staining at 36 h of 5 and 10 mM treatments had significantly higher density of GFAP than the control. Thus, ACR-induced effects can be seen in neuronal and astrocytic cells. These results suggest that ACR exposure may lead to apoptotic and astrogliotic effects in human astrocytoma cells in vitro in a time- and dose-dependent manner.     

Quercetin protects against ethanol-induced oxidative damage in rat primary hepatocytes

The pathogenesis and progression of alcoholic liver disease (ALD) are associated with free radical injury and oxidative stress, which could be partially attenuated by antioxidants and free radical scavengers. Quercetin, one of the most widely distributed flavonoids in plants, is a natural antioxidant. The hypothesis that quercetin could prevent the ethanol-induced oxidative damage in hepatocytes was investigated. The ethanol-intoxicated (100 mM for 8 h) rat primary hepatocytes were post-treated (2 h), simultaneously treated or pre-treated (2 h) with quercetin respectively, while the time-dependent (0.5–8 h) and dose-dependent (25–200 μM) quercetin pre-treatment were used in the present study. The parameters of lactate dehydrogenase (LDH), aspartate transaminase (AST), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were determined to address the alterations of cell damage and antioxidant state after quercetin intervention. The toxic insult of ethanol to hepatocytes was challenged by quercetin and these parameters almost returned to the level of control group when hepatocytes were pre-treated with quercetin at the dose of 50 μM for 2–4 h before ethanol exposure. In conclusion, quercetin pre-treatment provided protection against ethanol-induced oxidative stress in hepatocytes and may be used as a new natural drug for the prevention and/or treatment of ALD.     

Acrylamide-induced mitochondria collapse and apoptosis in human astrocytoma cells

Acrylamide (ACR) can be produced during food processing and has neurotoxic effects in humans. This study aims to determine ACR induced apoptotic responses in human astrocytoma U-1240 MG cells to realize the incurred toxic mechanisms. Under 1 and 2 mM ACR exposure, cell viability decreased as time increased. The increments in sub-G₁ phase were 87.5-fold, and pro-caspase 3 and PARP protein expressions decreased 35% and 54.5% respectively relative to the control after 2 mM ACR treatment. Molecular evidence of Bax/bcl-2 ratio and cytochrome c expression increased 8.86-fold and 6.81-fold as well as pro-caspase 9 decreased 67.8% relative to the control respectively under 2 mM ACR exposure. Trolox, an ROS scavenging agent, attenuated cell death and induced ROS production by 2 mM ACR. The ultrastructure alterations of mitochondria showed marked vesicular matrix compartmentalization and cytoplasmic vacuole formation after 2 mM ACR was treated for 48 h, whereas those treated for 72 h showed chromatin condensation, pyknosis, and swelling. These results indicate long-term exposure to ACR induced mitochondria collapse and finally led to apoptosis. Although 2 mM ACR is higher than average daily intake dosage, workers in chemical industries may be exposed to sufficient doses to entail health risks.     

Cytotoxicity and genotoxicity of phenazine in two human cell lines

Phenazine was recently identified as a drinking water disinfection byproduct (DBP), but little is known of its toxic effects. We examined in vitro cytotoxicity and genotoxicity of phenazine (1.9–123 μM) in HepG2 and T24 cell lines. Cytotoxicity was determined by an impedance-based real-time cell analysis instrument. The BrdU (5-bromo-2′-deoxyuridine) proliferation and MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assays were used to examine mechanisms of cytotoxicity. Genotoxicity was determined using the alkaline comet assay. Concentration-dependent cytotoxicity was observed in HepG2 cells, primarily due to an antiproliferative effect (BrdU 24 h IC₅₀: 11 μM; 48 h IC₅₀: 7.8 μM) observed as low as 1.9 μM. T24 cells experienced a minor antiproliferative effect (BrdU 24 h IC₅₀: 47 μM; 48 h IC₅₀: 17 μM). IC₅₀ values for HepG2 proliferation and viability were 54–77% lower compared to T24 cells. In both cell lines, IC₅₀ values for proliferation were 66–90% lower than those for viability. At phenazine concentrations producing equivalent cytotoxicity, HepG2 cells (1.9–30.8 μM) experienced no significant genotoxic effects, while T24 cells (7.7–123 μM) experienced significant genotoxicity at ⩾61.5 μM. While these effects were seen at phenazine concentrations above those found in disinfected water, the persistence of the antiproliferative effect and the differential toxicity in each cell line deserves further study.     

Sulforaphane mitigates cadmium-induced toxicity pattern in human peripheral blood lymphocytes and monocytes

Cadmium (Cd) is a highly toxic and widely distributed heavy metal that induces various diseases in humans through environmental exposure. Therefore, alleviation of Cd-induced toxicity in living organisms is necessary. In this study, we investigated the protective role of sulforaphane on Cd-induced toxicity in human peripheral blood lymphocytes and monocytes. Sulforaphane did not show any major reduction in the viability of lymphocytes and monocytes. However, Cd treatment at a concentration of 50 μM induced around 69% cell death. Treatment of IC₁₀-Cd and 100 μM sulforaphane combination for 24 and 48 h increased viability by 2 and 9% in cells subjected to Cd toxicity, respectively. In addition, IC₂₅ of Cd and 100 μM sulforaphane combination recovered 17–20% of cell viability. Cd induced apoptotic and necrotic cell death. Sulforaphane treatment reduced Cd-induced cell death in lymphocytes and monocytes. Our results clearly indicate that when the cells were treated with Cd + sulforaphane combination, sulforaphane decreased the Cd-induced cytotoxic effect in lymphocytes and monocytes. In addition, sulforaphane concentration plays a major role in the alleviation of Cd-induced toxicity.     

Mercury modulates the cytochrome P450 1a1, 1a2 and 1b1 in C57BL/6J mice: in vivo and in vitro studies

In the current study C57BL/6J mice were injected intraperitoneally with Hg^2 + in the absence and presence of TCDD. After 6 and 24 h the liver was harvested and the expression of Cyps was determined. In vitro, isolated hepatocytes were incubated with TCDD in the presence and absence of Hg^2 +. At the in vivo level, Hg^2 + significantly decreased the TCDD-mediated induction of Cyps at 6 h while potentiating their levels at 24 h. In vitro, Hg^2 + significantly inhibited the TCDD-mediated induction of Cyp1a1 in a concentration- and time-dependent manner. Interestingly, Hg^2 + increased the serum hemoglobin (Hb) levels in mice treated for 24 h. Upon treatment of isolated hepatocytes with Hb alone, there was an increase in the AhR-dependent luciferase activity with a subsequent increase in Cyp1a1 protein and catalytic activity levels. Importantly, when hepatocytes were treated for 2 h with Hg^2 + in the presence of TCDD, then the medium was replaced with new medium containing Hb, there was potentiation of the TCDD-mediated effect. In addition, Hg^2 + increased heme oxygenase-1 (HO-1) mRNA, which coincided with a decrease in the Cyp1a1 activity level. When the competitive HO-1 inhibitor, tin mesoporphyrin was applied to the hepatocytes there was a partial restoration of Hg^2 +-mediated inhibition of Cyp1a1 activity. In conclusion, we demonstrate for the first time that there is a differential modulation of the TCDD-mediated induction of Cyp1a1 by Hg^2 + in C57BL/6J mice livers and isolated hepatocytes. Moreover, this study implicates Hb as an in vivo specific modulator of Cyp1 family.     

Transient activation of protein kinase C contributes to fluoride-induced apoptosis of rat erythrocytes

Role of PKC in fluoride-induced apoptosis of rat erythrocytes was studied in vitro and in vivo. Treatment of erythrocytes with 5 mM NaF for 1–24 h caused progressive accumulation of cytosolic Ca²⁺ and PS exposure at outer membrane surface. After 1 h, these processes were suppressed by PKC inhibitors staurosporine, GF 109203X and chelerythrine, but increased by PKC activator PMA. Following 24 h, NaF-induced Ca²⁺ uptake and PS externalization were partly prevented by PMA or staurosporine, but not by GF 109293X and chelerythrine. Application of PP inhibitor OA augmented NaF-induced cell responses within 1 h, but not after 24 h. Incubation of erythrocytes with 0.1–10 mM NaF for 1 h produced a dose-dependent PKCα translocation from cytosol to membranes with appearance of active PKM fragment. 24 h NaF exposure led to complete loss of cytosolic PKCα and proteolysis of membrane PKCα. Besides, NaF weakly stimulated membrane PKCζ, although its subcellular distribution was not altered. Thus, transient PKCα activation/translocation positively contributes to NaF-induced apoptosis in vitro. Consumption of 2–20 ppm fluoride by the rats for 12 months also induced dose-dependent PKCα translocation to membranes and activation of membrane PKCζ, what indicates that PKC stimulation is an important physiological mechanism of fluoride toxicity.     

Toxicity assessment on trophoblast cells for some environment polluting chemicals and 17β-estradiol

The identification of reproductive toxicants is a major scientific challenge for human health. We investigated the effects of a selected group of environmental polluting chemicals mostly provided with estrogenic activity on the human trophoblast cell lines BeWo and HTR-8/SVneo. Cells were exposed for 24 h to various concentrations (from 0.1 pM to 1 mM) of atrazine (ATR), diethylstilbestrol (DES), para-nonylphenol (p-NP), resveratrol (RES) and 17 β-estradiol (E2) and assayed for cell viability and human beta-Chorionic Gonadotropin (β-hCG) secretion.Decrease of cell viability as respect to control, vehicle-treated, cultures was obtained for all chemicals in the concentration range of 1 μM–1 mM in both cell types.A parallel decrease of β-hCG secretion was observed in BeWo cells, at 1 μM–1 mM concentrations, with the only exception of ATR which caused an increase at concentrations up to 1 mM. β-hCG release was also unexpectedly inhibited by ATR, DES, p-NP and RES at non-toxic (pM–nM) concentrations.These findings raise concern about the negative, potential effects of various environmental polluting chemicals on pregnancy success and fetal health.     

Antitumor effects of a selenium heteropoly complex in K562 cells

The aim of this study was to investigate the anti-tumor effects and mechanism of the selenium heteropoly compound (C₂H₁₀N₂)₅ (NH₄)₄H₂[Se₂W₁₀V₈O₆₂]·9H₂O (SeWV) in K562 cells. The results showed that 0.32–10.15 × 10^–3 mmol/L SeWV could significantly inhibit the proliferation of K562 cells in vitro, as determined by the MTT assay, with IC₅₀ values of 3.07 and 2.69 × 10^–3 mmol/L after 48 and 72 h of treatment with SeWV, respectively. Studies of the cell cycle indicated that SeWV could induce K562 cells gathered in the G₂/M phase upon treatment for 24 and 48 h, and a significant sub-G1 peak was evident at 0.32 and 2.54 × 10^–3 mmol/L after treatment for 24 h. Morphological observations revealed typical apoptotic features. SeWVcaused the accumulation of Ca²⁺, Mg²⁺ and ROS, and the reduction of pH and mitochondrial membrane potential (MMP) in K562 cells as evidenced by confocal laser scanning microscopy. Experiments also showed that the expression of Bcl-2 was significantly inhibited, but Bax was increased by SeWV at 5.07 × 10^–3 mmol/L. Additionally, the content of cytochrome-C was increased after treatment for 24 h. The experiment implied that SeWV had anti-tumor activity and that its mechanism was partially attributable to the induction of cell cycle distribution and apoptosis that was induced by a change in intracellular ion homeostasis.     

Preventive effect of γ-glutamylcysteinylethyl ester on carbon tetrachloride-induced hepatic triglyceride accumulation in mice

The effect of γ-glutamylcysteinylethyl ester (γ-GCE), which is a precursor of reduced glutathione (GSH), on carbon tetrachloride (CCl₄)-induced hepatic triglyceride (TG) accumulation in mice was investigated in comparison with that of GSH. Administration of γ-GCE (160 μmol/kg), but not GSH (160 μmol/kg), to mice at 3 h after CCl₄ injection (1 ml/kg, i.p.) significantly attenuated an increase in hepatic TG concentration at 6, 12, and 24 h after the CCl₄ injection. A decrease in hepatic GSH concentration after the CCl₄ injection was significantly diminished by the γ-GCE administration, but not by the GSH administration. The correlation coefficient between hepatic TG concentration and hepatic GSH concentration was −0.627 (P<0.001) when the results of all mice were grouped together. These results indicate that γ-GCE can attenuate CCl₄-induced hepatic TG accumulation in mice through the maintenance of hepatic GSH level.     

Potential endocrine disrupting effect of ochratoxin A on human placental 3β-hydroxysteroid dehydrogenase/isomerase in JEG-3 cells at levels relevant to human exposure

Ochratoxin A (OTA) is a common foodborne mycotoxin. Besides its classical toxicities, it is also associated with the impairment of steroidogenesis in rats. It is hypothesized that OTA may act as an endocrine disruptor by intervening 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD). To address this hypothesis, human placental cells JEG-3 were used in vitro to examine the effects of short- and long-term OTA exposures on expression levels of 3β-HSD1 and progesterone secretion at 24–96 h. Results showed that both cytotoxic and non-cytotoxic levels of OTA induced 3β-HSD1 mRNA expression by 281–378% at 72 and 96 h. A significant induction (43–316%) of 3β-HSD1 protein expression was observed at 48, 72 and 96 h, and the progesterone production with the involvement of 3β-HSD1 was significantly increased by 22–89% after 48–96 h. This is the first study to demonstrate OTA up-regulates 3β-HSD1 expression in human placental cells, indicating the potential endocrine-disrupting property of OTA.     

Zinc attenuates ethanol-induced Sertoli cell toxicity and apoptosis through caspase-3 mediated pathways

Ethanol enhances apoptosis in testicular germ cells. Zinc reduces ethanol-induced apoptosis of somatic cells through inhibition of caspase-mediated pathways. Little is known about the effects of ethanol on Sertoli cells and the effects of Zinc on ethanol-induced testicular injury. The hypothesis tested was that ethanol enhances apoptosis of Sertoli cells through up-regulation of caspase-3 and Zinc inhibits ethanol-induced effects. Cultured Sertoli cells (TM4) were exposed to ethanol (160 mM), Zinc (8 μM) and Zinc prior to ethanol for duration of 24 or 48 h and their effects on TM4 cell viability was then investigated by MTT assay. Caspase-3 mRNA expression was also investigated using real-time RT-PCR. Cell viability decreased and caspase-3 mRNA expresstion increased in cells exposed to ethanol, while exposure to Zinc showed opposite effects. Pretreatment with Zinc recovered ethanol-induced anti-proliferative effects and over-expression of caspase-3. Zinc reduced ethanol-induced Sertoli cell toxicity and apoptosis via caspase-3 mediated pathways.     

Disposition and acute toxicity of imidacloprid in female rats after single exposure

Single dose of imidacloprid (IMI-20 mg/kg bodyweight) was orally administered in female rats. Its disposition along with two metabolites 6-chloro nicotinic acid (6-CNA) and 6-hydroxy nicotinic acid (6-HNA) was monitored in organs (brain, liver, kidney, and ovary) and bodily fluids (blood, urine) at 6, 12, 24 and 48 h and faeces at 24 and 48 h. Maximum concentration (C_max) of IMI and metabolites in each organ and bodily fluid occurred after 12 h. Area under curve (AUC) of IMI ranged from 35 to 358 μg/ml/h; 6-CNA: 27.12–1006.42 μg/ml/h and 6-HNA: 14.98–302.74 μg/ml/h in different organs and bodily fluids. Clearance rate of IMI was maximum in ovary followed by kidney, liver, brain, faeces, blood and urine. Percent inhibition of acetyl-cholinesterase (AChE) was comparable in brain and Red Blood Cells (RBC) at 6–48 h which suggests the RBC-AChE as valid biomarker for assessing IMI exposure. It is evident that IMI was absorbed, metabolized, and excreted showing increased level of serum enzymes like Glutamic oxaloacetic transaminase (GOT), Glutamic pyruvic transaminase (GPT) and biochemical constituents like billirubin and Blood Urea Nitrogen (BUN) at 48 h. These data suggest that IMI is widely distributed, metabolized and induced toxicology effects at 20 mg/kg bodyweight to female rats.     

Genistein induces morphology change and G2/M cell cycle arrest by inducing p38 MAPK activation in macrophages

Genistein is a well known natural compound which is present in soy foods and exerts many beneficial functions such as anticancer, anti-inflammatory and antioxidant. However, until now little is known about the effects of genistein on the function of macrophages. The murine macrophage cell line RAW264.7 was used as target cell line. The results show that at concentrations of 50–100 μM, genistein reduced cell viability to 70%–80% (after 24 h) and 50%–60% (after 48 h), which was due to G2/M phase cell cycle arrest. Treatment of the macrophages with genistein for 24 or 48 h also led to significant morphological changes, such as elongation of the cells and development of long pseudopodia-like protrusions. By staining the F-actin cytoskeleton, we observed accumulation of actin-filaments at the edges of the cells. The morphology change and G2/M phase arrest after genistein treatment is due to the activation of the phosphorylation of MAP kinase p38. The morphology change and cell cycle arrest can be significantly reverted when treatment is combined with p38 inhibitor SB203580. Moreover, after treatment of the macrophages with genistein for 24 and 48 h, the phagocytotic efficiency for Candida albicans was decreased in a time- and dose-dependent manner which correlates to the morphology change. The production of cytokines (TNF-α) stimulated by C. albicans was strongly inhibited by genistein. In conclusion, genistein showed a strong immune modulatory effect on the macrophages.