The Lead-Chelating Effects of Substituted Dithiocarbamates

The effectiveness of certain substituted dithiocarbamates in mobilizing lead from preexposed rats was investigated.The animals received 10mg Pb/kg/day, intragastrically.for 8 weeks and were treated thereafter with 400μmol/kg, intraperitoneally.of morpholine dithiocarbamate, tetraammonium ethylenediamine diacetic acid dithiocarbamate (EDDTC), ammonium diethanolamine dithiocarbamate (ADDTC), sodium diethyldithiocarbamate.N-benzyl-D-glucamine dithiocarbamate (NBGDTC), or dimercaptosuccinic acid, daily for 5 days.All the chelating agents were effective in lowering the hepatic and renal burden of Pb.ADDTC.EDDTC, and NBGDTC were also able to lower the long bone Pb content.The lowering of Pb burden had no relationship to restoration of Pb-induced hematopoietic alterations.The relatively lower lipophilicity of substituted dithiocarbamates, owing to the presence of hydrophilic groups, seems to be advantageous in preventing passage of metal chelale into the brain.None of the substituted dithiocarbamates caused excessive excretion of urinary Cu and Zn.ADDTC and EDDTC appear to be promising in the management of Pb poisoning. 1990 Academic Press.Inc.

A Facile and Efficient One-Pot Regioselective Synthesis of 2-Hydroxyalkyl Dithiocarbamates under Catalyst-Free Conditions

A simple catalyst-free, and highly regioselective approach to 2-hydroxyalkyl dithiocarbamates is described which involves a one-pot reaction of various amines and carbon disulfide,CS2, with epoxides in ethanol at room temperature.

Synthesis, Characterization and <i>In-Vitro</i>Antimicrobial Studies of M²⁺+ Complexes of <i>p</i>-Chlorophenyl-, <i>p</i>-Bromophenyl-Dithiocarbamates

This study reports the synthesis of metal complexes of mixed ligands p-Chlorophenyl-, p-Bromophenyl-dithiocarbamates. The spectral properties of the metal complexes [Zn(II), Cd(II), Hg(II), Cu(II), Co(II) and Ni(II)] were obtained using the FTIR and UV/Vis spectroscopic techniques. Their antibacterial studies revealed that these complexes as well as the ligands could serve as possible antibacterial agents against pathogens. Melting point and solubility measurements were also carried out. It was observed that these complexes were non-toxic, non-electrolytic and stable solids.

Molybdenum Dithiocarbamates:A New Approach to "Old" Technology

A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear MoDDCs.This control assists in the tailoring of specific tribological properties of the MoDDCs in both greases and lubricating oils.

Synthesis and biological activities of dithiocarbamates containing1,2,3-triazoles group

Twelve novel dithiocarbamates containing 1,2,3-trizaoles group were prepared via one step starting from organic halides, dithiocarbamic acid prop-2-ynyl ester, and sodium azide, using a very simple catalytic system composed of copper（I） chloride and water at 70 8C. The structures of the new compounds were characterized and screened for their in vitro anti-tumor. Four of the compounds displayed varying levels of anti-tumor activity against the CDC25 B.

An electron donor-acceptor photoactivation strategy for the synthesis of S-aryl dithiocarbamates using thianthrenium salts under mild aqueous micellar conditions

An eco-friendly and convenient method is developed herein for the synthesis of S-aryl dithiocarbamates via visible-light-induced SET process of an EDA complex between thianthrenium salt functionalized arenes and dithiocarbamate anions under mild aqueous micellar conditions.This strategy indirectly realizes the method for constructing S-aryl dithiocarbamates through site-selective C−H functionalization of arenes.Most importantly,the reaction proceeded smoothly without addition of any photocatalyst,and the by-product thianthrene is recycled in quantity,ultimately minimizing the production of chemical waste.This protocol provides a promising synthesis candidate for the construction of valuable S-aryl dithiocarbamates,which also opens up a new avenue for micellar photocatalysis.

Conformation and Antitumor Activity of Novel Metal Complexes of Piperazinedithioformates

The in vitro antitumour efficacy of some novel metal complexes of piperazinedi thioformates （SR-M） was examined in six cancer cell lines. The activity was compared with that of piperazinedithioformates. Biological evaluations of a series of SR-M compounds suggest that the compounds 1 c （SR-Cu） and If （SR-Sn） show a potent antitumor activity. The stable conformation structure of SR-Cu as a representative of SR-M was investigated and confirmed by computer workshop.

Effect of NF-κB inhibitor PDTC on VEGF and endostatin expression of mice with Lewis lung cancer

Objective:To investigate the effects of NF-κB inhibitor pyrrolidine dithiocarbamate hydrochloride(PDTC) on vascular endothelial growth factor(VEGF) and endostatin expression in mice with Lewis lung cance;and its mechanism.Methods:Mice survival rate and anti-tumor effects were observed in different concentrations of NF-κB inhibitor PDTC after the Lewis lung cancer mice model was established.VEGF and endostatin expressions were detected by immunohistochemical assay.Results:Lewis lung cancer was be inhibited by 0.5 mg/kg.1.5 mg/kg and 3.0 mg/kg of NF-κB inhibitor PDTC(P<0.05).Microvessel density(MVD) in 0.5 mg/kg.1.5 mg/kg and 3.0 mg/kg NF-κB inhibitor PDTC groups were significantly lower than the control group(P<0.05).Immunohistochemical assay results showed that VEGF and endostatin expressions in the 0.5 mg/kg.1.5 mg/kg and 3.0 mg/kg NF-κB inhibitor PDTC groups were significantly lower than the control group(P<0.05).Western blot results also showed that NF-κB inhibitor PDTC could inhibit VEGF and endostatin expressions in tumor tissues.Conclusions:NF-κB inhibitor PDTC can inhibit tumor formation and reduce tumor angiogenesis in mice with Lewis lung cancer;and its mechanism maybe associated to VEGF and endostatin down-regulation.

Evaluation of the effect of pyrrolidine dithiocarbamate in suppressing inflammation in mice with dextran sodium sulfate-induced colitis

AIM: To evaluate the effect of pyrrolidine dithio- carbamate (PDTC; an NF-κB inhibitor) administered at low (50 mg/kg) and high (100 mg/kg) doses in suppressing colitis in mice with dextran sodium sulfate (DSS)-induced colitis. METHODS: Mice were divided into a DSS-untreated group (normal group), DSS-treated control group, DSS+PDTC-treated groupⅠ(low-dose group), and DSS+PDTC-treated groupⅡ (high-dose group). In each group, the disease activity index score (DAI score), intestinal length, histological score, and the levels of activated NF-κB and inflammatory cytokines (IL-1β and TNF-α) in tissue were measured. RESULTS: The DSS+PDTC-treated groupⅡ exhibited suppression of shortening of intestinal length and reduction of DAI score. Activated NF-κB level and IL-1β and TNF-α levels were significantly lower in DSS+PDTC- treated groupⅡ. CONCLUSION: These findings suggest that PDTC is useful for the treatment of ulcerative colitis.

Activation of nuclear factor-kappa B and effects of pyrrolidine dithiocarbamate on TNBS-induced rat colitis

AIM: To explore the changes of nuclear factor-kappa B (NF-κB) DNA-binding activity, the expression of intercellular adhesion molecule-1(ICAM-1) regulated by IMF-κB at various times and to evaluate the effects of pyrrolidine dithiocarbamate (PDTC) on trinitrobenzene sulfonic acid (TNBS)-induced rat colitis. METHODS: TNBS of 0.6 mL was mixed with ethanol of 0.3 mL solution and instilled into the lumen of the rat colon. The rat models were divided into 6 groups, which were killed at 24 h, 3, 7,14, and 21 d after enema. Colonic inflammation and damage were assessed by macroscopical and histological criteria. Activity of NF-κB DNA-binding was analyzed by electrophoresis mobility shift assays (EMSA). Expression of ICAM-1 was detected by in situ hybridization (ISH) and immunohistochemistry (IH). Then various doses of PDTC were injected into rat abdomen 30 min before enema with TNBS/ethanol as pretreatment. The rats were killed 4 h after enema and the colonic inflammation, myeloperoxidase (MPO) activity, malondialdehyde (MDA) level, and DNA-binding activity of NF-κB were assessed. Finally, PDTC was injected intraperitoneally after colitis was induced. Changes of morphology were assayed. RESULTS: During the first week, hyperemia, hemorrhage, edema and ulceration of the colonic mucosa appeared with predominant infiltration of leukocytes. Neutrophils, macrophages, lymphocytes infiltrated in mucosa and submucosa 14 d later. Fibroblasts and granuloma-like structures were also obviously seen. The binding activity of NF-κB began to increase at 24 h time point and reached a peak at 14 d, then decreased but still was higher than control group at 21 d (P<0.01). Levels of ICAM-1 mRNA and protein significantly elevated at 24 h and the peak was at 21 d. Pretreatment with PDTC could attenuate the development of inflammation but not by reducing NF-KB activity. This attenuation of inflammation had a positive relationship with the dose of PDTC. PDTC at the dose of 100 mg/kg had no therapeutic effect after colitis was induced. CONCLUSION: NF-κB activation is an important event that may be involved in acute and chronic inflammation development and may contribute to self-protection against early inflammation damage. NF-κB also regulates ICAM-1 expression during colonic inflammation. Pretreatment of PDTC may attenuate the inflammation development. But PDTC has no therapeutic effect after the colitis is induced.

Pyrrolidine dithiocarbamate alleviates the anti-tuberculosis drug-induced liver injury through JAK2/STAT3 signaling pathway:An experimental study

Objective:To study the effect of pyrrolidine dithiocarbamate(PDTC) on the anti-tuberculosis drug-induced liver injury and the molecular mechanism. Methods:Clean male SD rats were selected as experimental animals and randomly divided into normal group,model group,PDTC group and AG490 group. Animal model of anti-tuberculosis drug-induced liver injury was established by intragastric administration isoniazid + rifampicin. PDTC group received intraperitoneal injection of PDTC,and AG490 group received intraperitoneal injection of AG490. Twenty-eight days after intervention,the rats were executed,and the liver injury indexes,inflammation indexes and oxidative stress indexes in serum as well as JAK2/STAT3 expression,liver injury indexes,inflammation indexes and oxidative stress indexes in liver tissue were determined. Results:p-JAK2,p-STAT3,TNF-α,IL-1β,IL-6,ROS,8-OHdG and MDA expression in liver tissue as well as TBIL,ALT,AST,γ-GT,TNF-α,IL-1β,IL-6,ROS,8-OHdG and MDA levels in serum of model group were significantly higher than those of normal group while p-JAK2,p-STAT3,TNF-α,IL-1β,IL-6,ROS,8-OHdG and MDA expression in liver tissu as well as TBIL,ALT,AST,γ-GT,TNF-α,IL-1β,IL-6,ROS,8-OHdG and MDA levels in serum of PDTC group and AG490 group were significantly lower than those of model group. Conclusions:PDTC can inhibit the inflammation and oxidative stress mediated by JAK2/STAT3 signaling pathway to alleviate the anti-tuberculosis drug-induced liver injury.

Complexation separation for vanadium and chromium by dithiocarbamate and its application in treatment of chromium-vanadium-bearing slag

A novel method for the separation and reclamation of vanadium and chromium from acidic solution was proposed. The principle for the separation is based on selective complexation. In specific, V(V) can be complexated by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(Ⅲ) remained in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(Ⅲ)-bearing solution can be reached by decomplexation and neutralization, respectively. The kinetics of the complexation reaction was studied. In addition, the precipitation ratio of vanadium reached 97% and the loss of chromium was less than 4% after process optimization. The complexing agent could be regenerated with a high ratio of 99.5%. The method was successfully applied to treating chromium-vanadium-bearing slag produced in conventional vanadium production industry. Vanadium and chromium could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%.

Protective effect of pyrrolidine dithiocarbamate on liver injury induced by intestinal ischemia-reperfusion in rats

BACKGROUND: The nuclear translocation of transcription factors may be a critical factor in the intracellular pathway involved in ischemia/reperfusion(I/R) injury. The aim of the study was to evaluate the role of nuclear factor-kappa B (NF-κB) in the pathogenesis of liver injury induced by intestinal ischemia/reperfusion (IIR) and to investigate the effect of pyrrolidine dithiocarbamate (PDTC) on this liver injury. METHODS: Male Wistar rats were divided randomly into three experimental groups (8 rats in each): sham operation group (control group); intestinal/reperfusion group(I/R group): animals received 1-hour of intestinal ischemia and 2-hour reperfusion; and PDTC treatment group (PDTC group): animals that received I/R subject to PDTC treatment (100 mg/kg). The histological changes in the liver and intestine were observed, and the serum levels of tumor necrosis factor-α (TNF-α), alanine aminotransferase (ALT), aspartate aminotransferase (AST), liver superoxide dismutase (SOD), and nitrite/nitrate (NO) were measured. The immunohistochemical expression and Western blot analysis of liver NF-κB and intercellular adhesion molecule-1(ICAM-1) were observed. RESULTS: IIR induced liver injury characterized by the histological changes of liver edema, hemorrhage, polymorphonuclear neutrophil (PMN) infiltration, and elevated serum levels of AST and ALT. The serum TNF-α level was significantly higher than that of the control group(P<0.01) and a high level of liver oxidant product was observed (P<0.01). These changes were parallel to the positive expression of NF-κB and ICAM-1. After the administration of PDTC, the histological changes after liver injury were improved; the levels of SOD and NO in the liver were elevated and reduced, respectively (P<0.01). The expressions of ICAM-1 and NF-κB in the liver were weakened (P<0.01). CONCLUSION: NF-κB plays an important role in the pathogenesis of liver injury induced by HR. PDTC, an agent known to inhibit the activation of NF-κB, can reduce and prevent this injury.

Cloud point extraction and flame atomic absorption spectrometry analysis of palladium, platinum, and gold ions from industrial polluted soil

Cloud point extraction (CPE) with Tergitol TMN-6 was applied for the extraction of trace amounts of palladium (Pd(Ⅱ)), platinum (Pt(Ⅳ)), and gold (Au(Ⅲ)) in the soil of industrial sewage. Ammonium pyrolysine dithiocarbamate (APDC) was adopted as the chelating agent prior to CPE and then was detected by atomic absorption spectrometry (AAS). Different parameters such as the concentration of surfactants, chelating agent and salt, sample pH, equilibration temperature and time, centrifugation time and rates, and the effect of foreign ions were studied. Under optimum conditions, the low limits of detections are 1.4, 2.8 and 1.2 ng·ml^-1 and the enrichment factors are 21, 12, and 24 for Pd(Ⅱ), Pt(Ⅳ), and Au(Ⅲ, respectively. The relative standard deviations vary from 0.6% to 1.0% (n=11). All correlation coefficients of the calibration curves are >0.9960. The proposed method was successfully applied for the determination of Pd(Ⅱ), Pt(Ⅳ), and Au(Ⅲ) in the real soil of industrial sewage samples.

Syntheses,Crystal Structures and Antibacterial Activities of Complexes [(C_9H_(18)NS_2)_3M(Ⅲ)](M = Sb and Bi)

Two novel complexes,[（C9H18NS2）3Sb（III）]（1） and [（C9H18NS2）3Bi（III）]（2）,were synthesized and characterized by elemental analysis,IR,TG and X-ray single-crystal diffraction.Both 1 and 2 crystallize in the monoclinic system,P21/c space group.The data for 1：a = 1.6964（3）,b = 1.02149（17）,c = 2.5650（3） nm,β = 121.824（8）°,Z = 4,V = 3.7766（10） nm^3,Dc = 1.293 g·cm^-3,F（000） = 1536,μ = 1.082 mm^-1,the final R = 0.0500,wR = 0.1562 and S =1.072.The data for 2：a = 1.6802（9）,b = 1.0256（6）,c = 2.5083（10） nm,β = 121.77（3）°,Z = 4,V = 3.675（3） nm^3,Dc = 1.486 g·cm^-3,F（000） = 1664,μ = 5.159 mm^-1,the final R = 0.0481,wR = 0.1055 and S =1.076.The coordinated geometry of the central M（III） with six sulfur atoms from three ligands is a distorted pentagonal pyramid configuration.The dimer structural system is formed by the weak interactions of M…S and C-H…S between two molecules.The complexes were valued for their antibacterial activities by agar-streak method.It was found that 1 is active against the four test bacterial organisms.

The Effects of PDTC plus Leflunomide and Cyclosporine on the NF-КB Signaling Pathway in Mouse-to-rat Cardiac Xenografts

In this study, the effects of pirrolidine dithiocarbamate （PDTC） plus leflunomide （Lef） and cyclosporine （CsA） on the NF-κB signaling pathway in mouse-to-rat cardiac xeno-transplantation models were investigated. NIH mice and Wistar rats served as donors and recipients respectively. Mouse-to-rat cardiac xenotransplantation was performed. The recipients were divided into 5 groups： group A （the control group）, group B （PDTC group）, group C （PDTC plus CsA group）, group D （PDTC plus Lef group） and group E （PDTC plus Lef and CsA group）. The expressions of IKKa/[3, NF-κB-P65, IκBct, ICAM-1 and NF-κB DNA binding activity in xenograft tissues were determined by immunohistochemistry and Western blot as well as electrophoretic mobility shift assay （EMSA）. The median survival time of cardiac xenografts in the control group, PDTC group, PDTC plus CsA group, PDTC plus Lef group and PDTC plus Lef and CsA group was （2.17±0.41）, （2.33±0.52）, （4.67±1.21）, （7.00±1.79） and （9.00±1.41） days respectively. The survival time of xenografts in the PDTC plus Lef and CsA group was significantly longer than that in other four groups （P〈0.05 for all）, that in the PDTC plus Lef group longer than that in the control group, PDTC group and PDTC plus CsA group （P〈0.05 for all）, that in PDTC plus CsA group longer than the control group and PDTC group （P〈0.05 for all）. The expressions of IKKα/β, NF-κB-P65, IκBα and ICAM-1 and NF-κ3 DNA binding activity were notably increased in mouse-to-rat cardiac xenografts. The expressions were decreased in the control group, PDTC group, PDTC plus CsA group, PDTC plus Lef and PDTC plus Lef and CsA group in turn. It was concluded that PDTC plus Lef and CsA can significantly suppress the expressions of IKKα/β, NF-κB-P65, IκBα, ICAM-1 and NF-κB DNA binding activity, thereby prolonging the survival of the cardiac xenografts.

S-adenosyl-L-methionine modifies antioxidant-enzymes,glutathione-biosynthesis and methionine adenosyltransferases-1/2 in hepatitis C virus-expressing cells

AIM: To elucidate the mechanism(s) by which S-adenosyl-L-methionine(SAM) decreases hepatitis C virus(HCV) expression.METHODS: We examined the effects of SAM on viral expression using an HCV subgenomic replicon cell culture system. Huh7 HCV-replicon cells were treated with 1 mmol/L SAM for different times(24-72 h), then total RNA and proteins were isolated. c DNA was synthesized and real time-PCR was achieved to quantify HCV-RNA, superoxide dismutase 1 and 2(SOD-1, SOD-2) catalase, thioredoxin 1, methionine adenosyltransferase 1A and 2A(MAT1A, MAT2A) expression, and GAPDH and RPS18 as endogenous genes. Expression of cellular and viral protein was evaluated by western-blot analysis using antibodies vs HCV-NS5 A, SOD-1, SOD-2, catalase, thioredoxin-1, MAT1 A, MAT2 A, GAPDH and actin. Total glutathione levels were measured at different times by Ellman's recycling method(0-24 h). Reactive oxidative species(ROS) levels were quantified by the dichlorofluorescein assay(0-48 h); Pyrrolidin dithiocarbamate(PDTC) was tested as an antioxidant control and H2O2 as a positive oxidant agent.RESULTS: SAM exposition decreased HCV-RNA levels 50%-70% compared to non-treated controls(24-72 h). SAM induced a synergic antiviral effect with standard IFN treatment but it was independent of IFN signaling. In addition, 1 mmol/L SAM exposition did not modify viral RNA stability, but it needs cellular translation machinery in order to decrease HCV expression. Total glutathione levels increased upon SAM treatment in HCV-replicon cells. Transcriptional antioxidant enzyme expression(SOD-1, SOD-2 and thioredoxin-1) was increased at different times but interestingly, there was no significant change in ROS levels upon SAM treatment, contrary to what was detected with PDTC treatment, where an average 40% reduction was observed in exposed cells. There was a turnover from MAT1A/MAT2 A, since MAT1 A expression was increased(2.5 fold-times at 48 h) and MAT2 A was diminished(from 24 h) upon SAM treatment at both the transcriptional and translational level. CONCLUSION: A likely mechanism(s) by which SAM diminish HCV expression could involve modulating antioxidant enzymes, restoring biosynthesis of glutathione and switching MAT1/MAT2 turnover in HCV expressing cells.

Pyrrolidine dithiocarbamate and saxagliptin ameliorate ulcerative colitis in rats

Objective: To evaluate the antioxidant, immunomodulatory and anti-inflammatory activities of pyrrolidine dithiocarbamate and saxagliptin in rats with thioacetamide-induced ulcerative colitis. Methods: Animals were orally administered with a vehicle, sulfasalazine(500 mg/kg), pyrrolidine dithiocarbamate(100 mg/kg), and saxagliptin(10 mg/kg) for two weeks. Ulcerative colitis was induced by a single intrarectal instillation of thioacetamide on day 8. Colon samples were collected to assess mitogen-activated protein kinase(MAPK), phosphorylated extracellular signal-regulated kinase(ERK), c AMP response element-binding protein(CREB), interleukin-12(IL-12), caspase-3, β-defensin, inducible nitric oxide synthase(i NOS) and glucagon like peptide-1(GLP-1). Moreover, histopathological examination was performed. Results: Rats treated with thioacetamide caused increases in colonic MAPK, phosphorylated ERK, CREB, caspase-3, IL-12, β-defensin, i NOS, as well as decreases in body weight and GLP-1. In addition, distortion of colonic structure was found by histopathological examination. Pyrrolidine dithiocarbamate and saxagliptin mitigated colitis severity by improving body weight decrease and GLP-1, and reducing colonic MAPK, phosphorylated ERK, CREB, caspase-3, IL-12, β-defensin and i NOS. Conclusions: Pyrrolidine dithiocarbamate and saxagliptin are efficient against thioacetamide induced colitis through improving inflammatory and oxidative changes.

CoFe_2O_4/CdS nanocomposite:Preparation,characterisation,and application in sonocatalytic degradation of organic dye pollutants

A magnetic CoFe2O4/Cd S nanocomposite was prepared via one-step hydrothermal decomposition of cadmium diethanoldithiocarbamate complex on the surface of CoFe2O4 nanoparticles at a low temperature of 200 ℃.The nanocomposite was characterised by X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）,scanning electron microscopy,energy-dispersive X-ray spectroscopy（EDX）,UV-visible spectroscopy,transmission electron microscopy（TEM）,N2 gas sorption analysis,X-ray photoelectron spectroscopy（XPS）,and vibrating sample magnetometry.The FT-IR,XRD,EDX and XPS results confirmed the formation of the CoFe2O4/Cd S nanocomposite.Based on the TEM analysis,the CoFe2O4/Cd S nanocomposite constituted nearly uniform,sphere-like nanoparticles of ～20 nm in size.The optical absorption spectrum of the CoFe2O4/Cd S nanocomposite displayed a band gap of 2.21 e V,which made it a suitable candidate for application in sono/photocatalytic degradation of organic pollutants.Accordingly,the sonocatalytic activity of the CoFe2O4/Cd S nanocomposite was evaluated towards the H2O2-assisted degradation of methylene blue,rhodamine B,and methyl orange under ultrasonic irradiation.The nanocomposite displayed excellent sonocatalytic activity towards the degradation of all dyes examined—the dyes were completely decomposed within 5–9 min.Furthermore,a comparison study revealed that the CoFe2O4/Cd S nanocomposite is a more efficient sonocatalyst than pure Cd S;thus,adopting the nanocomposite approach is an excellent means to improve the sonoactivity of Cd S.Moreover,the magnetic properties displayed by the CoFe2O4/Cd S nanocomposite allow easy retrieval of the catalyst from the reaction mixture for subsequent uses.

Effects of PDTC on the Proliferation and PCNA Expression of Human Retinal Pigment Epithelial Cells

To investigate the effects of pyrrolidine dithiocarbamate （PDTC） on the proliferation and PCNA （proliferating cell nuclear antigen） expression of cultured human retinal pigment epithelium cells, human retinal pigment epithelium cells （RPE） were cultured from normal adults who died accidentally. The effects of PDTC on the proliferation of RPE cells were examined by using methyl thiazlyl tetrazolium （MTT） assay. The effects of PDTC on the PCNA expression of RPE cells were immunohistochemically examined by employing biological image analysis system （BIAS）. After treatment with PDTC of various of concentration ranging from 0.062 to 1 g/L for 24 h, or concentrations ranging from 0.031 to 1 g/L, the proliferation of RPE cells decreased in a dose-dependent manner. After treatment with PDTC of concentration varying from 0. 062 to 1 g/L for 24 h, the PCNA expression was also suppressed in a dose-dependent manner. It is concluded that PDTC can inhibit the proliferation of RPE cells in vitro in a dose-and time-dependent manner, at least in part, by down-regulating the expression of PCNA. PDTC may be used to prevent and treat the proliferative vitreoretinopathy （PVR）.