Viability Of HeLa Cells Research Articles

Succinylated Apoptolidins from Amycolatopsis sp. ICBB 8242

Two new apoptolidins, 2'-O-succinyl-apoptolidin A (11) and 3'-O-succinyl-apoptolidin A (12), were isolated from the culture broth of an Indonesian Amycolatopsis sp. ICBB 8242. These compounds inhibit the proliferation and viability of human H292 and HeLa cells. However, in contrast to apoptolidin A (1), they do not inhibit cellular respiration in H292 cells. It is proposed that apoptolidins are produced and secreted in their succinylated forms and 1 is the hydrolysis product of 11 and 12.

Gold nanoparticle/ZnO nanorod hybrids for enhanced reactive oxygen species generation and photodynamic therapy

Gold nanoparticle (Au NP)@ZnO nanorod (NR) (Au@ZnO) hybrids with various ZnO:Au molar ratios were developed to enhance the generation of reactive oxygen species (ROS) in photodynamic therapy (PDT) applications. Introducing a metal/semiconductor heterostructure interface between Au NPs and ZnO NRs modulated electron transfer under ultraviolet (UV) irradiation, which dramatically suppressed the electron-hole recombination in ZnO and simultaneously increased the amount of excited electrons with high energy at Au NP surfaces. Hence, the ROS yield of the nanohybrid was considerably improved over those of pristine Au NPs or ZnO NRs alone and demonstrated a “1 + 1 > 2 effect.” This enhancement was strengthened with increases in the proportion of Au in the hybrid. The results showed that the Au@ZnO nanohybrids with a ZnO:Au ratio of 20:1 generated the highest ROS yield because they had the largest interface area between Au and ZnO, which in turn led to the lowest cell viability for HeLa and C2C12 cells during PDT. Furthermore, both ROS generation and cell destruction were positively correlated with nanohybrid dosage. The Au@ZnO hybrid (20:1, 100 μg/mL) resulted in HeLa cell viability as low as 28% after UV exposure for 2 min, which indicated its promising potential to improve the therapeutic efficacy of PDT.

Mitochondrial carnitine/acylcarnitine transporter, a novel target of mercury toxicity.

The effect of Hg(2+) and CH3Hg(+) on the mitochondrial carnitine/acylcarnitine transporter (CACT) has been studied on the recombinant protein and on the CACT extracted from HeLa cells or Zebrafish and reconstituted in proteoliposomes. Transport was abolished upon treatment of the recombinant CACT in proteoliposomes by Hg(2+) or CH3Hg(+). Inhibition was reversed by the SH reducing agent 1,4-dithioerythritol, GSH, and N-acetylcysteine. IC50 for Hg(2+) and CH3Hg(+) of 90 nM and 137 nM, respectively, were measured by dose-response analyses. Inhibition was abolished in the C-less CACT mutant. Strong reduction of inhibition by both reagents was observed in the C136A and some reduction in the C155A mutants. Inhibition similar to that of the WT was observed in the C23V/C58V/C89S/C155V/C283S mutant, containing only C136. Optimal inhibition by Hg(2+)was found in the four replacement mutants C23V/C58V/C89S/C283S containing both C136 and C155 indicating cross-reaction of Hg(2+) with the two Cys residues. Inhibition kinetic analysis showed mixed inhibition by Hg(2+) or competitive inhibition by CH3Hg(+). HeLa cells or Zebrafish were treated with the more potent inhibitor. Ten micromolar HgCl2 caused clear impairment of viability of HeLa cells. The transport assay in proteoliposomes with CACT extracted from treated cells showed that the transporter was inactivated and that DTE rescued the activity. Nearly identical results were observed with Zebrafish upon extraction of the CACT from the liver of the treated animals that, indeed, showed accumulation of the mercurial compound.

Pseudolaric acid B exerts antitumor activity via suppression of the Akt signaling pathway in HeLa cervical cancer cells.

Pseudolaric acid B (PAB) is a diterpene acid isolated from the bark of the root and trunk of Pseudolarix kaempferi Gordon (Pinaceae), which has demonstrated cytotoxic effects against various types of cancer. However, the mechanisms underlying the anticancer effects of PAB have remained to be elucidated. In the present study, the effects of PAB on the viability and apoptosis of HeLa cells were investigated by MTT assay, flow cytometric analysis of Annexin V-fluorescein isothiocyanate/propidium iodide staining, Rhodamine 123 staining and western blot analysis. The results demonstrated that PAB had antiproliferative and apoptosis-inducing effects on HeLa cells. PAB markedly inhibited HeLa cell viability in a time- and concentration-dependent manner. Flow cytometric analysis indicated that PAB induced apoptosis in HeLa cells in a dose-dependent manner. Treatment with PAB suppressed the expression of anti-apoptotic factor B cell lymphoma-2, and promoted the expression of pro-apoptotic factor Bcl-2-associated X protein. In addition, PAB induced an increase in Caspase-3 activity and loss of mitochondrial membrane potential, suggesting that this apoptosis may be mediated by mitochondrial pathways. Furthermore, the results of western blot analysis indicated that PAB was able to reduce Akt phosphorylation, thereby inhibiting the Akt pathway. These results suggested that PAB inhibited cell proliferation and induced apoptosis in HeLa cells, and that the anti-tumor effects of PAB were associated with inhibition of the Akt pathway. In conclusion, the results of the present study suggested that PAB may represent a novel therapeutic strategy for the treatment of human cervical cancer. However, additional studies are required to investigate the underlying apoptotic mechanisms.

Delivery of vincristine sulfate-conjugated gold nanoparticles using liposomes: a light-responsive nanocarrier with enhanced antitumor efficiency.

Rapid drug release at the specific site of action is still a challenge for antitumor therapy. Development of stimuli-responsive hybrid nanocarriers provides a promising strategy to enhance therapeutic effects by combining the unique features of each component. The present study explored the use of drug–gold nanoparticle conjugates incorporated into liposomes to enhance antitumor efficiency. A model drug, vincristine sulfate, was physically conjugated with gold nanoparticles and verified by UV-visible and fourier transform infrared spectroscopy, and differential scanning calorimetry. The conjugates were incorporated into liposomes by film dispersion to yield nanoparticles (113.4 nm) with light-responsive release properties, as shown by in vitro release studies. Intracellular uptake and distribution was studied in HeLa cells using transmission electron microscopy and confocal laser scanning microscopy. This demonstrated liposome internalization and localization in endosomal–lysosomal vesicles. Fluorescence intensity increased in cells exposed to UV light, indicating that this stimulated intracellular drug release; this finding was confirmed by quantitative analyses using flow cytometry. Antitumor efficacy was evaluated in HeLa cells, both in culture and in implants in vivo in nude mice. HeLa cell viability assays showed that light exposure enhanced liposome cytotoxicity and induction of apoptosis. Furthermore, treatment with the prepared liposomes coupled with UV light exposure produced greater antitumor effects in nude mice and reduced side effects, as compared with free vincristine sulfate.

Covalently-crosslinked mucin biopolymer hydrogels for sustained drug delivery

The sustained delivery of both hydrophobic and hydrophilic drugs from hydrogels has remained a challenge requiring the design and scalable production of complex multifunctional synthetic polymers. Here, we demonstrate that mucin glycoproteins, the gel-forming constituents of native mucus, are suitable for assembly into robust hydrogels capable of facilitating the sustained release of hydrophobic and hydrophilic drugs. Covalently-crosslinked mucin hydrogels were generated via exposure of methacrylated mucin to ultraviolet light in the presence of a free radical photoinitiator. The hydrogels exhibited an elastic modulus similar to that of soft mammalian tissue and were sensitive to proteolytic degradation by pronase. Paclitaxel, a hydrophobic anti-cancer drug, and polymyxin B, a positively-charged hydrophilic antibacterial drug, were retained in the hydrogels and released linearly with time over seven days. After four weeks of drug release, the hydrogels continued to release sufficient amounts of active paclitaxel to reduce HeLa cell viability and sufficient amounts of active polymyxin B to prevent bacterial proliferation. Along with previously-established anti-inflammatory, anti-viral, and hydrocarbon-solubilizing properties of mucin, the results of this study establish mucin as a readily-available, chemically-versatile, naturally-biocompatible alternative to complex multifunctional synthetic polymers as building blocks in the design of biomaterials for sustained drug delivery.

Bioactive compounds from crocodile (Crocodylus siamensis) white blood cells induced apoptotic cell death in hela cells.

Crocodile (Crocodylus siamensis) white blood cell extracts (WBCex) were examined for anticancer activity in HeLa cell lines using the MTT assay. The percentage viability of HeLa cells significantly deceased after treatment with WBCex in a dose- and time-dependent manner. The IC50 dose was suggested to be approximately 225 μg/mL protein. Apoptotic cell death occurred in a time-dependent manner based on investigation by flow cytometry using annexin V-FITC and PI staining. DAPI nucleic acid staining indicated increased chromatin condensation. Caspase-3, -8 and -9 activities also increased, suggesting the induction of the caspase-dependent apoptotic pathway. Furthermore, the mitochondrial membrane potential (ΔΨm ) of HeLa cells was lost as a result of increasing levels of Bax and reduced levels of Bcl-2, Bcl-XL, Bcl-Xs, and XIAP. The decreased ΔΨm led to the release of cytochrome c and the activation of caspase-9 and -3. Apoptosis-inducing factor translocated into the nuclei, and endonuclease G (Endo G) was released from the mitochondria. These results suggest that anticancer agents in WBCex can induce apoptosis in HeLa cells via both caspase-dependent and -independent pathways. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 986-997, 2016.

Inorganic photosensitizer coupled Gd-based upconversion luminescent nanocomposites for in vivo magnetic resonance imaging and near-infrared-responsive photodynamic therapy in cancers

Inorganic photosensitizer coupled Gd-based upconversion luminescent (UCL) nanocomposites have potential application for both magnetic resonance imaging (MRI) and photodynamic therapy (PDT) of cancers using the light stability and biocompatibility of TiO2 inorganic photosensitizer. However, TiO2 inorganic photosensitizer could only be excited by ultraviolet (UV) light, which was harmful and weakly penetrable in tissues. In this work, folic acid (FA)-targeted NaGdF4:Yb/Tm@SiO2@TiO2 nanocomposites (FA-Gd-Si-Ti NPs) were constructed and synthesized for both in vivo MRI and near infrared (NIR)-responsive inorganic PDT, in which TiO2 component could be excited by NIR light due to the UCL performance of NaGdF4:Yb/Tm component converting NIR to UV light. The results showed the as-prepared FA-Gd-Si-Ti NPs had good biocompatibility in vitro and in vivo. Moreover, MR study indicated that FA-Gd-Si-Ti NPs were good T1-weighted MRI contrast agents with high longitudinal relaxivity (r1) of 4.53 mm−1 s−1, also in vivo MRI of nude mice showed “bright” signal in MCF-7 tumor. Under the irradiation of 980 nm laser at the power density of 0.6 W/cm2 for 20 min, the viability of HeLa and MCF-7 cells incubated with FA-Gd-Si-Ti NPs could decrease from about 90 % to 35 % and 31%, respectively. Furthermore, in vivo PDT of MCF-7 tumor-bearing nude mice model showed that the inhibition ratio of tumors injected with FA-Gd-Si-Ti NPs reached up to 88.6% after 2-week treatment, compared with that of nude mice in control group. Based on the deep penetration of NIR light and the good biocompatibility of TiO2 inorganic photosensitizer, the as-prepared FA-Gd-Si-Ti NPs could have potential applications in both MRI and NIR-responsive PDT of cancers in deep tissues.

Hypoxia-inducible factor-2α (HIF-2α) mediates the effects of hypoxia on the promotion of HeLa cell viability, colony formation, and invasion capacity in vitro.

Hypoxia reduces the oxygen supply to tumor cells and may limit tumor cell growth. However, hypoxia promotes tumor cell metabolic adaptation, apoptosis resistance, angiogenesis, invasion, and metastasis. Hypoxia-inducible factor-2α (HIF-2α) may be responsible for these hypoxia-induced changes. In this study, we investigated the effects of hypoxia and HIF-2α knockdown in HeLa cells. HIF-2α shRNA lentivirus was used to knock down HIF-2α expression; cell viability, colony formation, invasion capacity, and gene expression were assessed. Hypoxia promoted HeLa cell growth, whereas knockdown of HIF-2α expression reduced HeLa cell viability under both normoxic and hypoxic conditions, with a greater effect observed under hypoxic conditions. Knockdown of HIF-2α expression also reduced HeLa cell colony formation and invasion capacity under both normoxic and hypoxic conditions. Expression of cyclooxygenase 2 and vascular endothelial growth factor was reduced after knockdown of HIF-2α expression, with a greater effect observed under hypoxic conditions. HIF-2α mediated the hypoxia-induced effect on the promotion of HeLa cell viability, colony formation, and invasion capacity in vitro. Further studies are needed to confirm the in vivo relevance of hypoxia and HIF-2α.

In vivo targeted magnetic resonance imaging and visualized photodynamic therapy in deep-tissue cancers using folic acid-functionalized superparamagnetic-upconversion nanocomposites.

Multifunctional nanoprobes used in magnetic resonance imaging (MRI) and photodynamic therapy (PDT) also have potential applications in diagnosis and visualized therapy of cancers, and hence it is important to investigate the active-targeting ability and in vivo reliability of these nanoprobes. In this work, folic acid (FA)-targeted, photosensitizer (PS)-loaded Fe3O4@NaYF4:Yb/Er (FA-NPs-PS) nanocomposites were synthesized for in vivo T2-weighted MRI and visualized PDT of cancers by modeling MCF-7 tumor-bearing nude mice. By measuring the upconversion luminescence (UCL) and fluorescence emission spectra, the as-prepared FA-NPs-PS nanocomposites showed near-infrared (NIR)-triggered PDT performance due to the production of a singlet oxygen species. Moreover, by tracing PS fluorescence in MCF-7, HeLa cells and in MCF-7 tumors, the FA-targeted nanocomposites demonstrated good targeting ability both in vitro and in vivo. Under the irradiation of a 980 nm laser, the viabilities of MCF-7 and HeLa cells incubated with FA-NPs-PS nanocomposites could decrease to about 18.4% and 30.7%, respectively, and the inhibition of MCF-7 tumors could reach about 94.9%. The transverse MR relaxivity of 63.79 mM(-1) s(-1) (r2 value) and in vivo MR imaging of MCF-7 tumors indicated an excellent T2-weighted MR performance. This work demonstrated that FA-targeted MRI/PDT nanoprobes are effective for in vivo diagnosis and visualized therapy of breast cancers.

Effects of the toluene and methanol extract of Senna (Cassia angustifolia Vahl) on viability and proliferation HeLa cells

Senna (Cassia angustifolia Vahl.) is used in food and pharmaceutical technologies as officinal drugs and natural laxative. The aim of the study was to investigate the effect of toluene and methanol Senna extracts on the viability and proliferation of HeLa cells. The senna leaves were extracted in Soxhlet's extractor and obtained toluene and methanolic extracts were used for determination of effects on viability and proliferation. Cytotoxic effect of different concentrations (0.1%, 0.01%, 0.001% and 0.0001%) extracts was investigated in HeLa cells in vitro. MTT test showed significant cytotoxic activity for toluene extract, especially the concentration of 0.1%, while the tested concentrations metanolic extract did not show cytotoxic activity.

A Novel Pharmacological Method to Study the Chinese Medicinal Formula Hua-Zheng-Hui-Sheng-Dan.

Objectives. Hua-Zheng-Hui-Sheng-Dan (HZHSD) was used as an experimental model to explore research methods of large formulae in traditional Chinese medicine (TCM) using current molecular biology approaches. Materials and Methods. The trypan blue exclusion assay was used to determine cell viability and cell numbers. Flow cytometry was used to assess cell cycle distribution and apoptosis. The concentration of cyclin D1 was analyzed by enzyme-linked immunosorbent assay. The median effect principle was used in drug combination studies. An orthogonal experimental design was used to estimate the effects of each herb at different concentrations. The HeLa xenograft mouse model was used to compare the antitumor activity of drugs in vivo. Results. Among the 35 herbs that comprise HZHSD, Radix Rehmanniae Preparata (RRP), Caesalpinia sappan (CS), Evodia rutaecarpa (ER), Folium Artemisiae Argyi (FAA), Leonurus japonicus Houtt (LJH), Tumeric (Tu), Radix Paeoniae Alba (RPA), and Trogopterus Dung (TD) effectively inhibited the proliferation of HeLa and SKOV3 cells. Only RRR had an effect on HeLa and SKOV3 cell viability. According to the median effect principle, Angelica sinensis (Oliv.) (AS), Tabanus (Ta), and Pollen Typhae (PT), which were proven to have a significant synergistic inhibitory effect on the proliferation of HeLa cells, were added to the original eight positive herbs. The combination of RPA and AS had a synergistic effect on inducing cell cycle S phase arrest and decreasing intracellular cyclin D1 in HeLa cells. By orthogonal experimental design, LJH and Tu were considered unnecessary herbs. The small formula (SHZHSD) consisted of RPA, AS, RRR, Ta., TD, PT, ER, CS, and FAA and was able to inhibit cell proliferation and induce cell apoptosis. The antitumor effects of HZHSD and SHZHSD were also compared in vivo. Conclusions. Through molecular biology approaches both in vitro and in vivo, research into single drugs, and analysis using the median effect principle and orthogonal experimental design, the small formula (SHZHSD) was determined from the original formula (HZHSD). SHZHSD exhibited superior antitumor activity compared with the original formula both in vitro and in vivo.

In VitroAntitumor Activity of a Keggin Vanadium-Substituted Polyoxomolybdate and Its ctDNA Binding Properties

A Keggin vanadium-substituted polyoxomolybdate, K5PMo10V2O40(PMo10V2), has been synthesized and it’s antitumor effect against Hela cells was investigated. The calf thymus DNA (ctDNA) binding ability of PMo10V2was also evaluated by UV-Vis absorption spectra and fluorescence spectra. The identity and high purity of PMo10V2was confirmed by elemental analysis and IR analysis. And the antitumor activity test of PMo10V2was carried out on Hela cancer cells line by MTT assay. The results of MTT assay show that PMo10V2significantly reduced the viability of Hela cells in a dose-dependent manner and exhibited stronger inhibitory activity against Hela cells at an IC50of 800 μg/mL, which is more effective than the positive control, 5-Fu(P<0.05). The results of the UV-Vis absorption spectra and fluorescence spectra indicated the groove or outside stacking binding between PMo10V2and ctDNA. These results show that the antitumor activity of PMo10V2may be caused by the interactions between DNA and PMo10V2.

Low-level laser therapy: Effects on human face aged skin and cell viability of HeLa cells exposed to UV radiation

Chronic and excessive exposure to UV radiation leads to photoaging and photocarcinogenesis. Adequate protection of the skin against the deleterious effects of UV irradiation is essential. Low-level laser therapy (LLLT) is a light source in the red to near-infrared range that has been accepted in a variety of medical applications. In this study, we explored the effect of LLLT in human face aged skin and the cell viability of HeLa cells exposed to UV radiation. We found that LLLT significantly reduced visible wrinkles and the loss of firmness of facial skin in aging subjects. Additionally, treatment of cultured HeLa cells with LLLT prior to or post UVA or UVB exposure significantly protected cells from UV-mediated cell death. All results showed the beneficial effects of LLLT on relieving signs of skin aging and its prevention and protection of the cell viability against UV-induced damage.

The puzzle of toxicity of gold nanoparticles. The case-study of HeLa cells

Data on the viability of HeLa cells exposed to functionalized gold nanoparticles have been analyzed on the basis of metrics based on the numerical particle concentration that takes into account both the size and shape of the nanoparticles.

Imiquimod treatment effectively reduces the percentage of viable cells in a cervical carcinoma cell line but does not affect the expression of HLA-G or OCT-4.

Cervical cancer is a challenging pathologic entity because of its lack of response to conventional chemotherapy. Imiquimod is a synthetic analogue which seems to activate skin immune cells, acting as a Toll-like receptor 7 agonist. Previous studies in the field of cervical cancer have showed that its application may play a significant role in the treatment of cervical HPV infection with or without cervical intraepithelial neoplasia (CIN). In the present study we investigate the therapeutic potential of imiquimod in a cervical carcinoma cell line and evaluate whether the expression of HLA-G and OCT-4 is altered during this treatment. HeLa cells were cultured in Dulbecco's modified Eagle medium and treated with 200 μl of imiquimod diluted solution (50 μg/ml). Cultured cells were allocated in four groups 1) control, 2) DMSO only, 3) DMSO and imiquimod for 48 hours, 4) DMSO and imiquimod for 72 hours. In the imiquimod treated cell lines we observed a significant reduction of viable cells at 48 and 72 hours (p = .001). The relative expression analysis of OCT-4 and HLA-G genes at 48 and 72 hours did not reveal significant differences after imiquimod treatment. Imiquimod effectively reduces the percentage of viable HeLa cells and should be further evaluated in future clinical trials. This effect takes place as of 48 hours after its initial application and seems to persist at least until 72 hours. HLA-G and OCT-4 expression is not affected by this type of treatment.

Phosphorescent Coordination Polymer Nanoparticles as a Three-in-One Platform for Optical Imaging, T1-Weighted Magnetic Resonance Imaging, and Photodynamic Therapy

Water-soluble coordination polymer nanoparticles (Ir–Gd CPPs) were conveniently synthesized in high yields in the presence of polyvinylpyrrolidone (PVP), adopting magnetic Gd(III) ions, and phosphorescent iridium complexes with carboxyl groups as building blocks. The Ir–Gd CPPs showed good stability in simulated biological media and low cytotoxicity toward a model line of HeLa cancer cells. The Ir–Gd CPPs exhibited absorption in the visible region, red phosphorescence centered at 560 nm, and higher longitudinal relaxivity (r1) of ∼29.5 mM–1 s–1 in a 3 T MRI system. Furthermore, the effective uptake of Ir–Gd CPPs by HeLa cells was confirmed by confocal laser scanning microscopy and flow cytometry, suggesting they may be useful as an optical probe for living cells. The generation of 1O2 upon irradiation with a visible light prompted an investigation into the possibility of using Ir–Gd CPPs in photodynamic therapy. After incubation with 200 μg mL–1 of Ir–Gd CPPs for 6 h, the viability of HeLa cells was only ∼16.6% after irradiation with a visible light (λ > 400 nm, 300 mW cm–2).

Effect of methyl jasmonate and silver nanoparticles on production of secondary metabolites by <i>Calendula officinalis</i> L (Asteraceae)

Purpose: To investigate the effects of two elicitors, methyl jasmonat (MeJA) and silver nanoparticles (SNPs), on the production of secondary metabolite by Calendula officinalis L (marigold).Methods: For the extract of the aerial part of the plant, membrane lipid peroxidation rate and 2, 2ˈdiphenylpicrylhydrazyl (DPPH) radical scavenging activity were assessed along with total anthocyanin, flavonoid, chlorophyll, carotenoids and saponin content. The effect of C. officinalis L extract with and without SNPs and MeJA on HeLa cell viability was also evaluated by methylthiazol tetrazolium (MTT) assay.Results: The presence of SNPs and MeJA in marigold extract increased membrane lipid peroxidation but decreased DPPH radical scavenging activity. Anthocyanin and flavonoid content also decreased in all the treatments investigated. Exposure to SNPs decreased chlorophyll and carotenoid content in the plant by 30 - 50 %, while MeJA increased them. In comparison with the control group, treatment with 0.4 mM SNPs and 100 μM MeJA increased saponin content in the plants by up to 177 %. Exposure of HeLa cells to the extracts of marigold significantly reduced their viability and this reduction was morepronounced when the plants were treated with MeJA and SNPs.Conclusion: Treatment of C. officinalis L. with SNPs and MeJA seems to be a simple and cost-effective method of improving the medicinal properties of this plant.Keywords: Calendula officinalis, Silver nanoparticles, Methyl jasmonate, Secondary metabolites, HeLa cells, Membrane lipid peroxidation, Radical scavenging

Diquat-induced cytotoxicity on Vero and HeLa cell lines: effect of melatonin and dihydromelatonin.

Diquat dibromide is a moderately toxic contact herbicide belonging to the bipyridyl group of redox-active compounds that induce a strong oxidative damage. Melatonin (MEL) can protect against oxidative damage under in vivo conditions, probably through its anti-oxidative capacity and ability to induce expression of anti-oxidative enzymes. The objective of this study was to investigate effects of diquat on viability of Vero and HeLa cells and possible protective effects of MEL and its analogue 2,3-dihydromelatonin (DMEL). Cell viability was evaluated with the MTT test. First, we analyzed dose-dependent effects of diquat on cell viability using the concentration range of 0.1–100 μM. Second, we used the diquat dose which reduced cell viability by 50% and treated cells with either MEL or DMEL (both in the concentration range of 1–100 μM) in the presence or absence of diquat. In addition, effects of both diquat and MEL on oxidative stress in HeLa cells were measured by flow cytometry using 2’,7’-dichlorofluorescin diacetate. We confirmed the expected negative effects of diquat on viability of Vero and HeLa cells. Melatonin and DMEL were able to prevent diquat reduced viability of Vero cells in rather low concentrations (1 μM) and DMEL exerted substantially stronger protective effects than MEL. However in HeLa cells, we did not find the same effects and MEL even reduced their viability. Moreover, treatment of HeLa cells with high concentrations of MEL (100 μM) exaggerated the pro-oxidative effects of diquat. The results suggest that in addition to the expected anti-oxidative effects, MEL exerts a pro-oxidative action which is cell type and dose dependent.

A thiosemicarbazone copper(II) complex as a potential anticancer agent

The preparation and the structure of a copper(II) complex, [Cu(4ML)Cl] (1) (H4ML = 2-acetylpyridine-4-methylthiosemicarbazone), are described. Complex 1 crystallizes in a monoclinic P21/c space group with a = 7.977(2) Å, b = 15.824(5) Å, c = 9.126(2) Å, α = γ = 90°, β = 91.974(2)°, V = 1151.26(5) Å3, Z = 4, F(0 0 0) = 620. According to X-ray crystallographic studies, each Cu(II) ion lies in a square planar coordination geometry based on the 4ML− and Cl− ligands. The complex displayed excellent inhibitory activity against various tumor cells (HeLa, HepG-2 and SGC-7901), offering lower IC50 value of 3.2 ± 0.7 μM than cisplatin (10 ± 2 μM) on HeLa cells at 48 h. Complex 1 could significantly suppress HeLa cell viability in a dose-dependent manner. Flow cytometric analysis showed that 1 induced HeLa cell apoptosis, which might be associated with cell cycle arrests at S and G2 phases. Consistent with results of DNA cleavage experiments, comet assay indicated that 1 caused severe DNA fragmentation. The production of ROS was elevated with increasing concentration of 1, suggesting that 1 was capable of promoting HeLa cell apoptosis through an oxidative DNA damage pathway.