A2780 Human Ovarian Cancer Cell Research Articles

Shikonin induces mitochondria-mediated apoptosis and attenuates epithelial-mesenchymal transition in cisplatin-resistant human ovarian cancer cells.

Cisplatin-based chemotherapy often results in the development of chemoresistance when used to treat ovarian cancer, which is difficult to overcome. The present study investigated the cytotoxic and anti-migratory effects of shikonin, a naphthoquinone compound, on cisplatin-resistant human ovarian cancer A2780 cells (A2780-CR). Shikonin had a potent dose-dependent cytotoxic effect on A2780-CR cells, with 9 µM shikonin treatment reducing A2780-CR cell viability by 50%, validate using an MTT assay. Shikonin induced apoptosis, as evidenced by the increased number of apoptotic bodies, following staining with Hoechst 33342, and terminal deoxynucleotidyl cell transferase dUTP nick end labeling-positive cells following treatment. Flow cytometry and fluorescent microscope imaging, following JC-1 staining, revealed that shikonin increased mitochondrial membrane depolarization. Also it altered the levels of apoptosis-associated proteins, leading to diminished expression of B cell lymphoma-2 (Bcl-2), enhanced expression of Bcl-associated X, and cleavage of caspase-9 and −3, as revealed using western blot analysis. Shikonin activated mitogen-activated protein kinases; while treatment with specific inhibitors of these kinases attenuated the decline in cell viability induced by shikonin treatment. In addition, the cell migration assay and western blot analysis indicated that shikonin decreased the migratory capacity of A2780-CR cells via the upregulation of epithelial-cadherin and downregulation of neural-cadherin. Taken together, the results of the present study indicated that shikonin induces mitochondria-mediated apoptosis and attenuates the epithelial-mesenchymal transition in A2780-CR cells.

Effects of 5-hydroxy-4'-nitro-7-propionyloxy-genistein on inhibiting proliferation and invasion via activating reactive oxygen species in human ovarian cancer A2780/DDP cells.

5-hydroxy-4'-nitro-7-propionyloxy-genistein (HNPG), a novel synthetic isoflavone derivative, was demonstrated to possess antitumor activity in gastric cancer and breast cancer in vitro, but its antitumor effect and mechanism in ovarian cancer has not been characterized. The aim of the present study was to investigate the effects of HNPG on inhibiting the proliferation and invasion in human ovarian cancer A2780 cell lines of cisplatin resistance (A2780/DDP) and elucidate its underlying molecular mechanism. The results indicated that HNPG presented with marked antitumor activity against A2780/DDP cells in vitro, significantly inhibited the rates of proliferation, clone formation, invasion and metastasis, and markedly induced apoptosis in dose- and time-dependent manner. Simultaneously, levels of reactive oxygen species (ROS) were increased and mitochondrial membrane potential was decreased. In addition, Bcl-2 expression was downregulated, Bax expression was upregulated, and the ratio of Bcl-2/Bax was decreased. Concurrently, levels of Cyt-C were markedly enhanced and the caspase cascade was triggered. Taken together, the results suggested that HNPG exerted anticancer effects through promoting ROS accumulation in cells, triggering mitochondrial apoptotic pathways and ultimately resulting in cells apoptosis. Therefore, HNPG serves as a potential candidate in the chemoprevention and/or treatment of cisplatin-resistant human ovarian cancer.

Imaging of a clickable anticancer iridium catalyst

Iridium-based anticancer reagents are receiving increasing attention for their high cytotoxicity. Herein, by activating CH bonds in the well-known antioxidant α-phenyl-N-tert-butylnitrone (PBN), we synthesized and characterized a series of new iridium complexes. Complex 1-AMP exhibited the best antiproliferation activity towards human ovarian cancer A2780 cells. The azide group in complex 1-AMP underwent the Cu(I)-catalysed azide−alkyne cycloaddition (CuAAC) reaction and the resulting fluorescent imaging in cells suggested it mainly accumulated in mitochondria. In comparison, to eliminate cytotoxicity of Cu(I) catalyst, we conducted a reaction between complex 1-AMP and a commercialized dye via strain-promoted alkyne–azide cycloaddition (SPAAC) reaction in live cells, confirming its targeting mainly in the mitochondria. Iridium-based anticancer complexes containing a nitrone ligand and azide group may offer a useful tool to probe the mechanism of metallodrugs.

Pt(IV)/Re(I) Chitosan Conjugates as a Flexible Platform for the Transport of Therapeutic and/or Diagnostic Anticancer Agents

New chitosan derivatives modified with (3-carboxypropyl)trimethylammonium chloride (1) and coupled with (OC-6-44)-diammine(4-carboxypropanoato)dichloridoethanolatoplatinum(IV) (2), were synthesized and their preliminary biological evaluation carried out in human tumor cells. Some of these derivatives were also loaded with a chelating ligand (3) that was derived from bis(quinolin-2-ylmethyl)amine to obtain chitosan-based nanoparticles for an EPR-mediated delivery of Pt(IV) prodrugs and Re(I) tricarbonyl complexes (4), to explore a multimodal theranostic approach to cancer. The cytotoxicity of the different chitosan conjugates (C12, C123, and C1234), carrying different combinations of the Pt(IV) complex, the chelator and the Re(I) complex, was evaluated in the A2780 human ovarian cancer cell line using the MTT assay. The Pt(IV)-containing nanosystems showed low to moderate cytotoxic activity (IC50 values in the range 13.5–33.7 µM) and was comparable to that found for the free Pt(IV) complex (IC50 = 13.7 µM). Therefore, the Pt(IV)-chitosan conjugation did not enhance the cytotoxic activity of the Pt(IV) prodrug, which certainly reflects the inefficient cellular uptake of the nanoconjugates. Nevertheless, a clearer view of their potential for the delivery of anticancer agents requires further in vivo tests because the EPR effect increases extravasation and retention within the tumor tissue, not necessarily within the tumor cells.

(−)-9′-O-(α-l-Rhamnopyranosyl)lyoniresinol from Lespedeza cuneata suppresses ovarian cancer cell proliferation through induction of apoptosis

Lespedeza cuneata (Dum. Cours.) G. Don. (Fabaceae), known as Chinese bushclover or sericea lespedeza, has been used in traditional medicine to treat diabetes, hematuria, and insomnia, and it has been reported that bioactive compounds from L. cuneata possess various pharmacological properties. However, there has been no study to determine the active compounds from L. cuneata with potential activity against ovarian cancer. This study aimed to isolate cytotoxic compounds from L. cuneata and identify the molecular mechanisms underlying the apoptosis pathway in ovarian cancer cells. Based on cytotoxic activity identified in the screening test, chemical investigation of the active fraction of L. cuneata led to the isolation of nine compounds including four lignanosides (1–4), three flavonoid glycosides (5–7), and two phenolics (8–9). Cytotoxicity and the molecular mechanism were examined by methyl thiazolyl tetrazolium (MTT) assay and Western blot analysis. Of the isolated compounds, (−)-9′-O-(α-l-rhamnopyranosyl)lyoniresinol (3) demonstrated the strongest effect in suppressing A2780 human ovarian carcinoma cell proliferation in a dose-dependent manner, with an IC50 value of 35.40 ± 2.78 μM. Control A2780 cells had normal morphology, whereas cell blebbing, shrinkage, and condensation were observed after treatment with compound 3. Western blotting analysis showed that compound 3 inhibited A2780 human ovarian cancer cell viability by activating caspase-8, caspase-3, and PARP, which contributed to apoptotic cell death. These results suggest that (−)-9′-O-(α-l-rhamnopyranosyl)lyoniresinol (3) has potent anticancer activities against A2780 human ovarian carcinoma cells through the extrinsic apoptotic pathway. Therefore, (−)-9′-O-(α-l-rhamnopyranosyl)lyoniresinol is an excellent candidate for the development of novel chemotherapeutics.

Liriopesides B inhibited cell growth and decreased CA125 level in human ovarian cancer A2780 cells

To study the effect of liriopesides B on cell growth curve, cell doubling time, the activity of tumour marker CA125 and alkaline phosphatase (AKP) in human ovarian cancer A2780 cells. Both cell growth curve and doubling time were studied by MTT assay, CA125 level and AKP activity were determined by respective kits. Results showed that liriopesides B could shift down the A2780 cells growth curve in a dose-time-dependent manner and inhibit the proliferation in A2780 cells with the maximum inhibitory rate 94.462% at 120 h, the doubling time was prolonged too. CA125 level was decreased in a dose-dependent way as well as AKP activity. Liriopesides B exhibited potential anticancer activity against human ovarian cancer A2780 cells.

Grifolin induces apoptosis and promotes cell cycle arrest in the A2780 human ovarian cancer cell line via inactivation of the ERK1/2 and Akt pathways.

Grifolin, a secondary metabolic product isolated from the mushroom Albatrellus confluence, has been demonstrated to possess antitumor activities in a variety of malignant cells. However, the signaling pathways and the molecular mechanisms underlying the anticancer effects of the agent in human ovarian cancer remain to be elucidated. The aim of the present study was to examine the effect of grifolin treatment on the human ovarian cancer cell line, A2780. MTT and flow cytometry analysis were used to analyze the viability of A2780 cells following treatment with grifolin. Western blotting was used analyze the expression of apoptosis-associated and cell cycle arrest-associated proteins. The results of MTT assays and flow cytometry analysis revealed that grifolin suppressed cell viability, induced apoptosis and triggered cell cycle arrest. Western blotting revealed that grifolin treatment resulted in inactivation of protein kinase B (Akt) and extracellular signal-related kinase 1/2 (ERK1/2), accompanied by upregulation of Bcl-2 associated X, apoptosis regulator, cleaved-caspase-3 and cleaved-poly (ADP-ribose) polymerase, and downregulation of B cell lymphoma-2, cyclin dependent kinase 4 and cyclinD1. The results of the present study indicated that grifolin had significant anti-cancer effects on the human ovarian cancer A2780 cells, which occurred via the Akt and ERK1/2 signaling pathways to at least a certain extent. These results demonstrate the therapeutic potential of grifolin as a treatment for ovarian cancer.

Kudsuphilactone B, a nortriterpenoid isolated from Schisandra chinensis fruit, induces caspase-dependent apoptosis in human ovarian cancer A2780 cells.

A phytochemical study on the fruits of Schisandra chinensis led to the isolation and characterization of nineteen compounds. The structures of the isolates were determined to be schizandrin, deoxyschizandrin, angeloylgomisin H, gomisin A, gomisin J, (-)-gomisin L1, (-)-gomisin L2, wuweizisu C, gomisin N, meso-dihydroguaiaretic acid, kadsuphilactone B, α-ylangenol, α-ylangenyl acetate, β-chamigrenal, β-chamigrenic acid, 4-hydroxybenzoic acid, protocatechuic acid, p-methylcarvacrol, and indole-3-acetic acid. Of these, some lignans and a nortriterpene showed cytotoxic activity in human ovarian and endometrial cancer cells. In particular, a nortriterpenoid kadsuphilactone B exhibited significant cytotoxic activity with IC50 values below 25μM in both A2780 and Ishikawa cells. Kadsuphilactone B induced apoptotic cell death and stimulated the activation of caspase-3, -8, and -9 and the cleavages of poly (ADP-ribose) polymerase. Caspase inhibitors attenuated the pro-apoptotic activity of kudsuphilactone B. In addition, kadsuphilactone B altered the expression levels of B cell lymphoma 2 (Bcl-2) family proteins. Moreover, activation of MAPKs was modulated by kadsuphilactone B in a dose-dependent manner. Taken together, these results show that kadsuphilactone B induces caspase-dependent apoptosis in human cancer cells via the regulation of Bcl-2 family protein and MAPK signaling.

Expression of Inorganic Pyrophosphatase (PPA1) Correlates with Poor Prognosis of Epithelial Ovarian Cancer

Ovarian serous carcinoma (OSC) is the most common epithelial ovarian cancer. Inorganic pyrophosphatase (PPA1) catalyzes the hydrolysis of pyrophosphate to inorganic phosphate, thereby providing extra energy for metabolism. The significance of PPA1 in the prognosis of OSC has not been investigated. Our study aimed to explore the expression and predictive role of PPA1 in OSC progression. We screened the expression of PPA1 protein in OSC tissues from 139 patients by immunohistochemistry, and evaluated its correlation with clinicopathological characteristics. PPA1 was categorized as high expression in 58 OSC cases (41.7%), which was correlated with poor differentiation, positive lymph node (LN) metastasis and advanced FIGO (The International Federation of Gynecology and Obstetrics) stages. Univariate and multivariate analyses identified PPA1 as a novel independent prognostic biomarker in OSC patients; meanwhile, conventional factors such as LN status and FIGO stages also showed statistical significance. Moreover, the expression levels of PPA1 protein were higher in A2780 and OVCAR3 human ovarian cancer cell lines than those in normal ovarian surface epithelial cells. Using these ovarian cancer cell lines, we showed that PPA1 overexpression caused the decrease in the expression level of p53, the tumor suppressor, with the increase in β-catenin level, as determined by Western blot analysis. Conversely, knockdown of PPAI expression was associated with the increase of p53 level and the decreased of β-catenin level. Consistently, the proliferation and invasion capacities of ovarian cancer cells were enhanced upon PPA1 overexpression. In conclusion, PPA1 serves as a potential prognostic biomarker for patients with OSC.

Cytotoxic Effects of Strawberry, Korean Raspberry, and Mulberry Extracts on Human Ovarian Cancer A2780 Cells.

Reactive oxygen species are tumorigenic by their ability to increase cell proliferation, survival, and cellular migration. The purpose of the present study was to compare the antioxidant activity and cytotoxic effects of 3 berry extracts (strawberry, Korean raspberry, and mulberry) in A2780 human ovarian carcinoma cells. Except for raspberry, the ethyl acetate or methylene chloride fractions of berries containing phenolic compounds exerted dose dependent free radical scavenging activities. In the raspberry fractions, the hexane fraction also exhibited potent antioxidant activity. The cytotoxic effects of berries extracts in A2780 human ovarian carcinoma cells were measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Surprisingly, co-treatment with n-butanol (BuOH) fractions of berries showed stronger cytotoxic effects compared to the other fractions. These findings suggest that potent anticancer molecules are found in the BuOH fractions of berries that have stronger cytotoxic activity than antioxidants.

Differential Cytotoxic Potential of Silver Nanoparticles in Human Ovarian Cancer Cells and Ovarian Cancer Stem Cells.

The cancer stem cell (CSC) hypothesis postulates that cancer cells are composed of hierarchically-organized subpopulations of cells with distinct phenotypes and tumorigenic capacities. As a result, CSCs have been suggested as a source of disease recurrence. Recently, silver nanoparticles (AgNPs) have been used as antimicrobial, disinfectant, and antitumor agents. However, there is no study reporting the effects of AgNPs on ovarian cancer stem cells (OvCSCs). In this study, we investigated the cytotoxic effects of AgNPs and their mechanism of causing cell death in A2780 (human ovarian cancer cells) and OvCSCs derived from A2780. In order to examine these effects, OvCSCs were isolated and characterized using positive CSC markers including aldehyde dehydrogenase (ALDH) and CD133 by fluorescence-activated cell sorting (FACS). The anticancer properties of the AgNPs were evaluated by assessing cell viability, leakage of lactate dehydrogenase (LDH), reactive oxygen species (ROS), and mitochondrial membrane potential (mt-MP). The inhibitory effect of AgNPs on the growth of ovarian cancer cells and OvCSCs was evaluated using a clonogenic assay. Following 1–2 weeks of incubation with the AgNPs, the numbers of A2780 (bulk cells) and ALDH+/CD133+ colonies were significantly reduced. The expression of apoptotic and anti-apoptotic genes was measured by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Our observations showed that treatment with AgNPs resulted in severe cytotoxicity in both ovarian cancer cells and OvCSCs. In particular, AgNPs showed significant cytotoxic potential in ALDH+/CD133+ subpopulations of cells compared with other subpopulation of cells and also human ovarian cancer cells (bulk cells). These findings suggest that AgNPs can be utilized in the development of novel nanotherapeutic molecules for the treatment of ovarian cancers by specific targeting of the ALDH+/CD133+ subpopulation of cells.

Human adipose mesenchymal stem cell-derived exosomal-miRNAs are critical factors for inducing anti-proliferation signalling to A2780 and SKOV-3 ovarian cancer cells.

An enigmatic question exists concerning the pro- or anti-cancer status of mesenchymal stem cells (MSCs). Despite growing interest, this question remains unanswered, and the debate became intensified with new evidences backing each side. Here, we showed that human adipose MSC (hAMSC)-derived conditioned medium (CM) exhibited inhibitory effects on A2780 human ovarian cancer cells by blocking the cell cycle, and activating mitochondria-mediated apoptosis signalling. Explicitly, we demonstrated that exosomes, an important biological component of hAMSC-CM, could restrain proliferation, wound-repair and colony formation ability of A2780 and SKOV-3 cancer cells. Furthermore, hAMSC-CM-derived exosomes induced apoptosis signalling by upregulating different pro-apoptotic signalling molecules, such as BAX, CASP9, and CASP3, as well as downregulating the anti-apoptotic protein BCL2. More specifically, cancer cells exhibited reduced viability following fresh or protease-digested exosome treatment; however, treatment with RNase-digested exosomes could not inhibit the proliferation of cancer cells. Additionally, sequencing of exosomal RNAs revealed a rich population of microRNAs (miRNAs), which exhibit anti-cancer activities by targeting different molecules associated with cancer survival. Our findings indicated that exosomal miRNAs are important players involved in the inhibitory influence of hAMSC-CM towards ovarian cancer cells. Therefore, we believe that these comprehensive results will provide advances concerning ovarian cancer research and treatment.

LC-MS Based Sphingolipidomic Study on A2780 Human Ovarian Cancer Cell Line and its Taxol-resistant Strain

Drug resistance elicited by cancer cells continue to cause huge problems world-wide, for example, tens of thousands of patients are suffering from taxol-resistant human ovarian cancer. However, its biochemical mechanisms remain unclear. Sphingolipid metabolic dysregulation has been increasingly regarded as one of the drug-resistant mechanisms for various cancers, which in turn provides potential targets for overcoming the resistance. In the current study, a well-established LC-MS based sphingolipidomic approach was applied to investigate the sphingolipid metabolism of A2780 and taxol-resistant A2780 (A2780T) human ovarian cancer cell lines. 102 sphingolipids (SPLs) were identified based on accurate mass and characteristic fragment ions, among which 12 species have not been reported previously. 89 were further quantitatively analyzed by using multiple reaction monitoring technique. Multivariate analysis revealed that the levels of 52 sphingolipids significantly altered in A2780T cells comparing to those of A2780 cells. These alterations revealed an overall increase of sphingomyelin levels and significant decrease of ceramides, hexosylceramides and lactosylceramides, which concomitantly indicated a deviated SPL metabolism in A2780T. This is the most comprehensive sphingolipidomic analysis of A2780 and A2780T, which investigated significantly changed sphingolipid profile in taxol-resistant cancer cells. The aberrant sphingolipid metabolism in A2780T could be one of the mechanisms of taxol-resistance.

New potently bioactive alkaloids from Crinum erubescens

Antimalarial bioassay-guided fractionation of the swamp lily Crinum erubescens led to the isolation of four compounds with potent antiplasmodial activity. Compounds 1 and 2 were determined from their spectroscopic data to be the known pesticidal compound cripowellin A and the known pesticidal and antiproliferative compound cripowellin B. 1D and 2D-NMR techniques were used to determine the identities of 3 and 4 as the new compounds cripowellin C and D. A fifth compound was identified as the known alkaloid hippadine, which was inactive against Plasmodium falciparum. The antiplasmodial IC50 values of compounds 1–4 were determined to be 30±2, 180±20, 26±2, and 260±20nM, respectively, and their antiproliferative IC50 values against the A2780 human ovarian cancer cell line were 11.1±0.4, 16.4±0.1, 25±2, and 28±1nM.

Abstract 1356: Cell-based screening to identify repressors of wild type and mutated telomerase reverse transcriptase gene promoter activity

Abstract Cellular immortality is a near-universal phenotype of cancer cells with the central role played by the multicomponent telomerase complex firmly established. The reactivation of telomerase is found in approximately 85% of all cancers. Furthermore, frequent activating non-coding mutations in the hTERT promoter region have been identified in multiple tumour types. A considerable body of evidence supports the concept of targeting the signal transduction pathways that contribute to telomerase overexpression in cancer cells. We have exploited our knowledge in this area to develop cell-based luciferase reporter gene assays to measure hTERT and hTR gene promoter activity. To this end we undertook high throughput screening in the A2780 human ovarian cancer cell line against both hTR and hTERT promoters. Secondary specificity and cytotoxicity assays reduced the initial hits to a single chemical series of dual inhibitors which strongly suppress both hTR and hTERT promoter activity without primary cytotoxicity, as predicted of telomerase inhibitors. Through a process of Hit to Lead we have further developed the chemical series. Lead compounds are active across a panel of cell lines from distinct histological origins, reduce endogenous hTERT mRNA levels and decrease telomerase catalytic activity at nM concentrations. Furthermore, these compounds repress both wild type and mutant C228T and C250T hTERT promoter activity. In specificity assays no off-target activity has been identified in an expanded promoter screen against a panel of 15 off-target promoter reporters. Citation Format: Alan Bilsland, Yu Liu, Sharon Burns, David Jenkinson, Jon Roffey, W. Nicol Keith. Cell-based screening to identify repressors of wild type and mutated telomerase reverse transcriptase gene promoter activity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1356.

MT2-MMP induces proteolysis and leads to EMT in carcinomas.

Epithelial-mesenchymal transition (EMT) is critical for carcinoma invasiveness and metastasis. To investigate the role of membrane-type-2 matrix metalloproteinase (MT2-MMP) in EMT, we generated lentiviral constructs of wild-type (WT) and an inactive Glu260Ala (E260A) mutant MT2-MMP and derived stably transfected HCT116 and A549 cell lines. WT-transfected cells appeared mesenchymal-like, whereas cells transfected with the E260A mutant were epithelial-like, as were cells treated with an MMP inhibitor (GM6001). Expression of E-cadherin, β-catenin, and zonula occludens-1 was lower in cells transfected with WT MT2-MMP compared to vector controls, cells treated with GM6001, or cells transfected with the E260A mutant. An 80-kD N-terminal fragment of E-cadherin was immunoprecipitated in conditioned medium from WT MT2-MMP cells, but not in the medium from vector controls, cells treated with GM6001, or E260A mutant cells. When endogenous expression of MT2-MMP in A2780 human ovarian cancer cells was inhibited using GM6001 or MT2-MMP-specific siRNA, levels of the 80-kD E-cadherin fragment in conditioned medium were decreased. Chick embryo chorioallantoic membrane invasion assays demonstrated that cells transfected with WT MT2-MMP were more invasive than cells transfected with control vector, treated with GM6001, or transfected with the E260A mutant. These results suggest that MT2-MMP degrades adherens and tight junction proteins and results in EMT, making it a potential mediator of EMT in carcinomas.

Pluronic F68-Linoleic Acid Nano-spheres Mediated Delivery of Gambogic Acid for Cancer Therapy.

Gambogic acid (GA), a natural compound from gamboge resin, has been introduced as a promising antitumor drug contributing to its broad spectrum of antitumor activity. However, the poor aqueous solubility and short half-life hinder its clinical application. Pluronic F68 (F68) is a well-known amphiphilic block copolymer consisting of hydrophobic propylene oxide units and hydrophilic ethylene oxide. Although F68 has an amphiphilic structure, its short propylene oxide segment limits its dilution stability and drug-loading capacity. To overcome this limitation, we modified F68 by conjugating linoleic acid, a hydrophobic fatty acid, to increase the hydrophilic-hydrophobic interaction and thus improve the stability of F68 nano-spheres. This F68-linoleic acid (F68-LA) conjugate was synthesized and was used to load GA to improve its anticancer effects. GA-loaded F68-LA nano-spheres were stable for 6days, with a mean diameter of 159.3nm and zeta potential of -23.2mV. The entrapment efficiency of GA in F68-LA nano-spheres was as high as 92.0%. Furthermore, F68-LA/GA nano-spheres exhibited an enhanced cytotoxic activity and proapoptotic effect against human ovarian cancer A2780 cells, compared with free GA. Our results showed that the F68-LA/GA nano-spheres might be a promising cancer-targeted drug delivery system in ovarian cancer therapy.

Hydrosulfide Adducts of Organo-Iridium Anticancer Complexes.

Novel half-sandwich hydrosulfidoiridium(III) complexes [(η(5)-Cp*)Ir(phen)(SH)]PF6 (1), [(η(5)-Cp*)Ir(bpy)(SH)]PF6 (2), [(η(5)-Cp(biph))Ir(phen)(SH)]PF6 (3), and [(η(5)-Cp(biph))Ir(bpy)(SH)]PF6 (4) were prepared from the chlorido complexes by dechlorination and treatment with excess NaSH·xH2O; phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine, Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl, and Cp(biph) = 1,2,3,4-tetramethyl-5-biphenylcyclopentadienyl. Complexes 1-4 were characterized by various techniques including electrospray ionization mass spectrometry, NMR spectroscopy (δ(SH) ca. -2 ppm), and a single-crystal X-ray analysis. Complex [(η(5)-Cp*)Ir(phen)(SH)]BPh4 (1') shows a typical piano-stool geometry with Ir-S bond length of 2.388(2) Å. Cp(biph) complexes 3 (IC50 = 0.98 μM) and 4 (IC50 = 0.61 μM) showed significantly higher (p < 0.005) in vitro antiproliferative activity against A2780 human ovarian cancer cells, as compared with their Cp* analogues 1 (IC50 = 49.5 μM) and 2 (IC50 = 48.4 μM), and potency similar to the anticancer drug cisplatin. The complexes were relatively stable in aqueous solution toward hydrolysis and reactions with reduced glutathione (GSH), 9-ethylguanine, or 9-methyladenine. Interestingly, GSH was readily oxidized to glutathione disulfide in the presence of Cp(biph) complexes 3 and 4, as judged by (1)H NMR, perhaps indicative of a possible redox-linked mechanism of action.

Dinuclear arene ruthenium thiolato complexes with fluorous side-chains

Four complexes of the general formula [(η6-p-MeC6H4Pri)2Ru2(μ-SC2H4R)3]+, R=(CF2)7CF3 (1), (CF2)5CF3 (2), (CF2)3CF3 (3) and (CH2)5CH3 (4) were synthesized and characterized. The molecular structures of complexes 1 and 3 were confirmed by single crystal X-ray diffraction analysis of their chloride salts. Complexes 3 and 4 were evaluated for their antiproliferative activity against human ovarian cancer A2780 and A2780cisR cell lines and against the non-tumorigenic HEK293 cell line. Complexes 3 and 4 are highly cytotoxic (IC50 values in the nanomolar range) and exhibit a slight selectivity for cancer cells over the model healthy cells.

Antiproliferative Triterpenoid Saponins from Leptaulus citroides Baill. from the Madagascar Rain Forest.

Bioassay-guided fractionation of EtOH extracts obtained from the roots and wood of the Madagascan plant Leptaulus citroides Baill. (Cardiopteridaceae) led to the isolation of ethyl esters of three new triterpenoid saponins (1–3) and the known sesquiterpenoid cinnamosmolide (4). The structures of 1–3 were elucidated by extensive 1D and 2D NMR experiments and mass spectrometry. Compounds 1, 2, and 4 showed moderate cytotoxicity against the A2780 human ovarian cancer cell line with IC50 values of 2.8, 10.2 and 2.0 µM, respectively.Graphical Electronic supplementary materialThe online version of this article (doi:10.1007/s13659-015-0083-1) contains supplementary material, which is available to authorized users.