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In this study we demonstrated for the first time synthetic procedures for composites of salinomycin (SalH) and two-line ferrihydrite. The products were characterized by various methods such as elemental analysis, attenuated total reflectance–Fourier-transform spectroscopy (ATR-FTIR), electron paramagnetic resonance spectroscopy (EPR), powder X-ray diffraction analysis (XRD), electrospray-ionization mass spectrometry (ESI-MS), thermogravimetric analysis with differential thermal analysis (DTA) and mass spectrometry (TG-DTA/MS). The EPR spectra of the isolated compounds consisted of signals associated with both isolated Fe3+ ions and magnetically coupled Fe3+ ions. Powder XRD analyses of the isolated products showed two intense and broad peaks at 9° and 15° 2Θ, corresponding to salinomycinic acid. Broad peaks with very low intensity around 35°, assigned to two-line ferrihydrite, were also registered. Based on the experimental results, we concluded that salinomycin sodium reacted with Fe(III) chloride to form composites consisting of two-line ferrihydrite and salinomycinic acid. One of the composites exerted pronounced antitumor activity in the sub-micromolar concentration range against human cervical cancer (HeLa), non-small-cell lung cancer (A549), colon cancer (SW480), and ovarian teratocarcinoma (CH1/PA1) cells. [ABSTRACT FROM AUTHOR]

In this contribution we report the synthesis, characterization and in vitro anticancer activity of novel cyclometalated 4-phenylthiazole-derived ruthenium(II) (2a–e) and osmium(II) (3a–e) complexes. Formation and sufficient purity of the complexes were unambigiously confirmed by 1H-, 13C- and 2D-NMR techniques, X-ray diffractometry, HRMS and elemental analysis. The binding preferences of these cyclometalates to selected amino acids and to DNA models including G-quadruplex structures were analyzed. Additionally, their stability and behaviour in aqueous solutions was determined by UV-Vis spectroscopy. Their cellular accumulation, their ability of inducing apoptosis, as well as their interference in the cell cycle were studied in SW480 colon cancer cells. The anticancer potencies were investigated in three human cancer cell lines and revealed IC50 values in the low micromolar range, in contrast to the biologically inactive ligands. [ABSTRACT FROM AUTHOR]

The reaction of (1R,2R)-(cyclohexane-1,2-diamine)dichloridoplatinum(II) with maleic acid unexpectedly resulted in the formation of an organometallic platinum(II) complex featuring a C,O-coordinating ligand. Additionally, a small series of close derivatives with increasing lipophilicity was synthesized. All complexes were fully characterized by multinuclear one- and two-dimensional (1H, 13C, 15N, and 195Pt) NMR spectroscopy, high resolution mass spectrometry, and in one case by X-ray diffraction. The lipophilicity and the impact on the DNA secondary structure as well as the cytotoxic properties in three human cancer cell lines (A549, SW480, and CH1/PA-1) were investigated. Unexpectedly, no clear-cut trend in cytotoxicity was observed with increasing lipophilicity. Also unexpectedly, the complexes showed only a low potential to inhibit cancer cell growth and no sign of interaction with DNA, in sharp contrast to the parent drug oxaliplatin, which seems to be caused by the low reactivity of the investigated compounds. [ABSTRACT FROM AUTHOR]

A series of thirty novel tetracarboxylatoplatinum(IV) complexes in trans-configuration featuring combinations of mixed ammine, methylamine, dimethylamine, and cyclopentylamine ligands as well as acetato/propanoato and trifluoropropanoato ligands was synthesised. The platinum(IV) complexes were characterised by one- and two-dimensional multinuclear NMR spectroscopy (1H, 13C, 15N, 19F, 195Pt), ESI-MS, elemental analysis, and X-ray diffraction. Additional parameters such as reduction behaviour and lipophilicity were measured via NMR spectroscopy and RP-HPLC, revealing slow reduction and a broad spectrum of log kw values in line with the respective ligand combination. In order to determine structure–activity relationships, cytotoxic activity was evaluated via the MTT assay in three human cancer cell lines (CH1/PA-1, ovarian teratocarcinoma, SW480, colon adenocarcinoma, A549, non-small-cell lung carcinoma). The induction of apoptosis and necrosis was determined in SW480 cells via the flow-cytometric annexin V/PI assay. In general, a tendency of higher lipophilicity leading to higher cytotoxicity was noticed. In contrast, lipophilicity alone plays a subordinate role for the induction of apoptosis, which strongly depends on the combination of am(m)ine and trifluoropropanoato ligands. [ABSTRACT FROM AUTHOR]

Quaternary ammonium palmitoyl glycol chitosan (GCPQ) has already shown beneficial drug delivery properties and has been studied as a carrier for anticancer agents. Consequently, we synthesised cytotoxic platinum(IV) conjugates of cisplatin, carboplatin and oxaliplatin by coupling via amide bonds to five GCPQ polymers differing in their degree of palmitoylation and quaternisation. The conjugates were characterised by 1H and 195Pt NMR spectroscopy as well as inductively coupled plasma mass spectrometry (ICP-MS), the latter to determine the amount of platinum(IV) units per GCPQ polymer. Cytotoxicity was evaluated by the MTT assay in three human cancer cell lines (A549, non-small-cell lung carcinoma; CH1/PA-1, ovarian teratocarcinoma; SW480, colon adenocarcinoma). All conjugates displayed a high increase in their cytotoxic activity by factors of up to 286 times compared to their corresponding platinum(IV) complexes and mostly outperformed the respective platinum(II) counterparts by factors of up to 20 times, also taking into account the respective loading of platinum(IV) units per GCPQ polymer. Finally, a biodistribution experiment was performed with an oxaliplatin-based GCPQ conjugate in non-tumour-bearing BALB/c mice revealing an increased accumulation in lung tissue. These findings open promising opportunities for further tumouricidal activity studies especially focusing on lung tissue. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and biological activity of tungstenocenes with varying biologically active (O,O–), (S,O–) and (N,O–) chelates are described. Complexes were characterized by 1H and 13C NMR, elemental analysis, ESI-mass spectrometry, FT-IR spectroscopy and X-ray diffraction analysis. The aqueous stability was studied by UV/Vis spectroscopy and the WIV to WV process by cyclic voltammetry. The cytotoxicity was determined by the MTT assay in A549, CH1/PA-1 and SW480 cancer cells as well as in IMR-90 human fibroblasts. Extensive biological evaluation was performed in three other human cancer cell lines (HCT116, HT29 and MCF-7) in monolayer and multicellular tumor spheroid cultures to better understand the mode of action. Lead compounds showed promising in vitro anticancer activity in all cancer cell lines. Further studies yielded important insights into apoptosis induction, ROS generation, different patterns in metal distribution (detected by LA-ICP-TOF-MS), changes in KI67 (proliferation marker) expression and DNA interactions. The results based on qualitative and quantitative research designs show that complexes containing (S,O–) chelates are more active than their (O,O–) and (N,O–) counterparts. The most striking results in spheroid models are the high antiproliferative capacity and the different distribution pattern of two complexes differing only in a W–S or W–O bond. [ABSTRACT FROM AUTHOR]

Based on their drug delivery properties and activity against tumors, we combined PAMAM dendrimers with various platinum(IV) complexes in order to provide an improved approach of anticancer treatment. Platinum(IV) complexes were linked to terminal NH2 moieties of PAMAM dendrimers of generation 2 (G2) and 4 (G4) via amide bonds. Conjugates were characterized by 1H and 195Pt NMR spectroscopy, ICP-MS and in representative cases by pseudo-2D diffusion-ordered NMR spectroscopy. Additionally, the reduction behavior of conjugates in comparison to corresponding platinum(IV) complexes was investigated, showing a faster reduction of conjugates. Cytotoxicity was evaluated via the MTT assay in human cell lines (A549, CH1/PA-1, SW480), revealing IC50 values in the low micromolar to high picomolar range. The synergistic combination of PAMAM dendrimers and platinum(IV) complexes resulted in up to 200 times increased cytotoxic activity of conjugates in consideration of the loaded platinum(IV) units compared to their platinum(IV) counterparts. The lowest IC50 value of 780 ± 260 pM in the CH1/PA-1 cancer cell line was detected for an oxaliplatin-based G4 PAMAM dendrimer conjugate. Finally, in vivo experiments of a cisplatin-based G4 PAMAM dendrimer conjugate were performed based on the best toxicological profile. A maximum tumor growth inhibition effect of 65.6% compared to 47.6% for cisplatin was observed as well as a trend of prolonged animal survival. [ABSTRACT FROM AUTHOR]

A series of six highly lipophilic Cp‐substituted molybdenocenes bearing different bioactive chelating ligands was synthesized and characterized by NMR spectroscopy, mass spectrometry and X‐ray crystallography. In vitro experiments showed a greatly increased cytotoxic potency when compared to the non‐Cp‐substituted counterparts. In vivo experiments performed with the dichlorido precursor, (Ph2C−Cp)2MoCl2 and the in vitro most active complex, containing the thioflavone ligand, showed an inhibition of tumour growth. Proteomic studies on the same two compounds demonstrated a significant regulation of tubulin‐associated and mitochondrial inner membrane proteins for both compounds and a strong metabolic effect of the thioflavone containing complex. [ABSTRACT FROM AUTHOR]

Combining therapeutic with diagnostic agents (theranostics) can revolutionize the course of malignant diseases. Chemotherapy, hyperthermia, or radiation are used together with diagnostic methods such as magnetic resonance imaging (MRI). In contrast to conventional contrast agents (CAs), which only enable non-specific visualization of tissues and organs, the theranostic probe offers targeted diagnostic imaging and therapy simultaneously. Methods: Novel salinomycin (Sal)-based theranostic probes comprising two different paramagnetic metal ions, gadolinium(III) (Gd(III)) or manganese(II) (Mn(II)), as signal emitting motifs for MRI were synthesized and characterized by elemental analysis, infrared spectral analysis (IR), electroparamagnetic resonance (EPR), thermogravimetry (TG) differential scanning calorimetry (DSC) and electrospray ionization mass spectrometry (ESI-MS). To overcome the water insolubility of the two Sal-complexes, they were loaded into empty bacterial ghosts (BGs) cells as transport devices. The potential of the free and BGs-loaded metal complexes as theranostics was evaluated by in vitro relaxivity measurements in a high-field MR scanner and in cell culture studies. Results: Both the free Sal-complexes (Gd(III) salinomycinate (Sal-Gd(III) and Mn(II) salinomycinate (Sal-Mn(II)) and loaded into BGs demonstrated enhanced cytotoxic efficacy against three human tumor cell lines (A549, SW480, CH1/PA-1) relative to the free salinomycinic acid (Sal-H) and its sodium complex (Sal-Na) applied as controls with IC50 in a submicromolar concentration range. Moreover, Sal-H, Sal-Gd(III), and Sal-Mn(II) were able to induce perturbations in the cell cycle of treated colorectal and breast human cancer cell lines (SW480 and MCF-7, respectively). The relaxivity (r1) values of both complexes as well as of the loaded BGs, were higher or comparable to the relaxivity values of the clinically applied contrast agents gadopentetate dimeglumine and gadoteridol. Conclusion: This research is the first assessment that demonstrates the potential of Gd(III) and Mn(II) complexes of Sal as theranostic agents for MRI. Due to the remarkable selectivity and mode of action of Sal as part of the compounds, they could revolutionize cancer therapy and allow for early diagnosis and monitoring of therapeutic follow-up. [ABSTRACT FROM AUTHOR]

The synergistic combination of the anticancer drug carboplatin and the iron chelator deferoxamine (DFO) served as a foundation for the development of novel multifunctional prodrugs. Hence, five platinum(IV) complexes, featuring the equatorial coordination sphere of carboplatin, and one or two DFO units incorporated at axial positions, were synthesized and characterized using ESI-HRMS, multinuclear (1H, 13C, 15N, 195Pt) NMR spectroscopy and elemental analysis. Analytical studies demonstrated that the chelating properties of the DFO moiety were not compromised after coupling to the platinum(IV) core. The cytotoxic activity of the compounds was evaluated in monolayer (2D) and spheroid (3D) cancer cell models, derived from ovarian teratocarcinoma (CH1/PA-1), colon carcinoma (SW480) and non-small cell lung cancer (A549). The platinum(IV)–DFO prodrugs demonstrated moderate in vitro cytotoxicity (a consequence of their slow activation kinetics) but with less pronounced differences between intrinsically chemoresistant and chemosensitive cell lines as well as between 2D and 3D models than the clinically used platinum(II) drug carboplatin. [ABSTRACT FROM AUTHOR]

A series of 15 piano-stool complexes featuring either a RuII, RhIII or IrIII metal center, a bidentate thiopyridone ligand, and different leaving groups was synthesized. The leaving groups were selected in order to cover a broad range of different donor atoms. Thus, 1-methylimidazole served as a N-donor, 1,3,5-triaza-7-phosphaadamantane (pta) as a P-donor, and thiourea as a S-donor. Additionally, three complexes featuring different halido leaving groups (Cl, Br, I) were added. Leaving group alterations were carried out with respect to a possible influence on pharmacokinetic and pharmacodynamic parameters, as well as the cytotoxicity of the respective compounds. The complexes were characterized via NMR spectroscopy, X-ray diffraction (where possible), mass spectrometry, and elemental analysis. Cytotoxicity was assessed in 2D cultures of human cancer cell lines by microculture and clonogenic assays as well as in multicellular tumor spheroids. Furthermore, cellular accumulation studies, flow-cytometric apoptosis and ROS assays, DNA plasmid assays, and laser ablation ICP-MS studies for analyzing the distribution in sections of multicellular tumor spheroids were conducted. This work demonstrates the importance of investigating each piano-stool complexes' properties, as the most promising candidates showed advantages over each other in certain tests/assays. Thus, it was not possible to single out one lead compound, but rather a group of complexes with enhanced cytotoxicity and activity. [ABSTRACT FROM AUTHOR]

A series of 16 dinuclear thiopyridone‐based organometallics with excellent water solubility, increased stability and remarkable cytotoxicity were synthesized and characterized. The complexes of this work formed dimeric species featuring a double positive charge in polar protic solvents, accounting for their outstanding solubility in aqueous solution. Most of them displayed higher antiproliferative activity than their parental thiomaltol complex, with unexpected cytotoxicity trends depending on the employed metal center, ligand modification, and cell line. Insights into their behavior in biological systems were gathered by means of amino‐acid interaction studies, cytotoxicity tests in 3D spheroid models, laser ablation, cellular accumulation measurements, as well as cell cycle experiments. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and biological activity of molybdenum(IV) complexes containing Trofimenko's scorpionato ligand, hydrotris(3‐isopropylpyrazolyl)borate (TpiPr), in addition to varying biologically active as well as other conventional ligands is described. Ligands employed include (O,O‐) (S,O‐) (N,N‐) donors that have been successfully coordinated to the molybdenum center by means of oxygen‐atom transfer (OAT) reactions from the known MoVI starting material, TpiPrMoO2Cl. The synthesized complexes were characterized by standard analytical methods and where possible by X‐ray diffraction analysis. The aqueous stability of the compounds was studied by means of UV/Vis spectroscopy and the impact of the attached ligand scaffolds on the oxidation potentials (MoIV to MoV) was studied by cyclic voltammetry. Utilizing polyvinylpyrrolidone (PVP) as a solubilizing agent, adequate aqueous solubility for biological tests was obtained. Anticancer activity tests and preliminary mode of action studies have been performed in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Novel phthiocol-based organometallics with in situ formed tridentate N,O,O-coordination motif were established via three-component microwave assisted one-pot reaction. These complexes exhibited enhanced stability in aqueous solution compared to the parental compound KP2048 and showed unexpected cytotoxic behaviour and selectivity in 2D and 3D cell cultures. [ABSTRACT FROM AUTHOR]

• Diaminetetracarboxylatoplatinum(IV) complexes are potential anticancer prodrugs. • Novel complexes exhibited IC 50 values down to the low micromolar range. • Lipophilicity and reduction for two compound series was determined. • Lipophilicity as well as reduction were found to parallel the cytotoxic properties. A series of novel bis(carboxylato)oxalatobis(1-propylamine)platinum(IV) complexes as well as an ethylamine analog were synthesized. The compounds are either symmetrical with both axial ligands consisting of monoesters of succinic acid, or unsymmetrical, with one axial ligand being acetate. The compounds were characterized in detail by elemental analysis, mass spectrometry and multinuclear (1H, 13C, 15N, 195Pt) NMR spectroscopy. The reduction behavior was followed by NMR spectroscopy, while lipophilicity was determined by analytical reversed-phase HPLC measurements. The capacity of inhibiting proliferation of the human cancer cell lines A549 (non-small cell lung cancer), CH1(PA-1) (ovarian teratocarcinoma) and SW480 (colon carcinoma) was evaluated by the MTT assay. In the most sensitive cell line CH1(PA-1), all compounds exhibited IC 50 values in the lower µM range. In general, the IC 50 values decreased with increasing lipophilicity within the two compound series. Nevertheless, replacing one of the succinic ester ligands with acetate has a rather marginal impact on antiproliferative activity and is hardly disadvantageous. [ABSTRACT FROM AUTHOR]

The oxaliplatin derivative (SP‐4‐3)‐oxalato[(1R,2R,4R/1S,2S,4S)‐(4‐trifluoromethyl‐cyclohexane‐1,2‐diamine)]platinum(II) hosting a trifluoromethyl group at position 4 of the cyclohexane ring is presented. The ligand was synthesized as an 1R,2R,4R/1S,2S,4S racemic mixture starting from 4‐trifluoromethyl‐cyclohexanol over five steps and coordinated to platinum to yield first the dichlorido and subsequently the oxalato complex. This novel compound and its analogue featuring a (13C2)oxalate ligand were characterized by multinuclear (1H, 13C, 15N, 19F, 195Pt) one‐ and two‐dimensional NMR spectroscopy. Ligand exchange and adduct formation reactions with DMSO, NaCl, CaCl2, l‐methionine, and 5′‐GMP were investigated via time‐dependent measurements by 19F and 13C NMR spectroscopy. The cytotoxicity of the title complex was investigated in three human cancer cell lines; the IC50 values were found in the low micromolar range, attesting moderate to high antiproliferative activity, depending on the cell line. A racemic mixture of an analogue of the clinically established anticancer drug oxaliplatin featuring a CF3 group at position 4 of the cyclohexane ring was synthesized and fully characterized. Its binding to DMSO, chloride, 5′‐GMP, and l‐methionine was investigated by 19F and 13C NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A series of 11 novel ruthenium(ii) arene complexes [Ru(p-cym)(trzC^N)L]NO3 based on the cycloruthenated 1,2,3-triazole scaffold (trzC^N) bearing different N- or S-donor leaving groups (L) were prepared. These complexes exhibited strongly diverging pH-dependent stability profiles, but consistently exerted antiproliferative effects in the low micromolar range in three cancer cell lines (A549, SW480, CH1/PA-1). The interaction with biomolecules was correlated to dissociation of the monodentate leaving group. Under oxidative conditions, the stably bound dimethylsulfide ligand (3a) undergoes oxidation, while metal coordination is maintained, affording the labile DMSO complex (3b). Rationalization of the homogenous antiproliferative activities was attempted by determination of the cellular accumulation and lipophilicity indices (Φ0). Investigations on their mechanism of action revealed that these metalacycles are inducers of apoptosis, exert a slight antioxidative effect in cell culture studies, but have no DNA intercalatory activity. [ABSTRACT FROM AUTHOR]

An orally active osmium anticancer compound was reliably quantified in the organs of treated mice by inductively coupled plasma-mass spectrometry (ICP-MS) by adding a stabilizing solution consisting of ascorbic acid, thiourea and EDTA during sample preparation and avoiding oxidizing conditions. The limits of detection (LOD) and quantification (LOQ) of 189Os were determined in liver tissue to be 0.02 and 0.075 μg kg−1, respectively. In spiked liver tissue, the internal precision showed a relative standard deviation (RSD) of 4%, a matrix recovery of 92% and a digestion recovery of 99%. A similar quantification protocol was developed for cellular accumulation studies in vitro. The cells were lysed with a non-oxidizing lysis buffer consisting of 150 mmol L−1 NaCl, 1.0% Triton X-100, 0.1% SDS, and 50 mmol L−1 Tris at pH 8.0 before adding the stabilizing solution. The osmium compound was compared with an isosteric ruthenium analogue and they displayed similar cellular accumulation and organ distribution profiles. [ABSTRACT FROM AUTHOR]

Organometallic metal(arene) anticancer agents require ligand exchange for their anticancer activity and this is generally believed to confer low selectivity for potential cellular targets. However, using an integrated proteomics-based target-response profiling approach as a potent hypothesis-generating procedure, we found an unexpected target selectivity of a ruthenium(arene) pyridinecarbothioamide (plecstatin) for plectin, a scaffold protein and cytolinker, which was validated in a plectin knock-out model in vitro. Plectin targeting shows potential as a strategy to inhibit tumor invasiveness as shown in cultured tumor spheroids while oral administration of plecstatin-1 to mice reduces tumor growth more efficiently in the invasive B16 melanoma than in the CT26 colon tumor model. [ABSTRACT FROM AUTHOR]

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Hydroxypyr(id)ones constitute an emerging platform for the design of drug molecules, owing to their favorable biocompatibility and toxicity profiles. Herein, [RuII(η6-p-cymene)] complexes with 3-hydroxy-2-pyridinone functionalized with morpholine and thiomorpholine, as a means often used in medicinal chemistry to alter the physicochemical properties of drug compounds, are reported. The compounds underwent hydrolysis of the Ru−Cl bond and the aqua species were stable for up to 48 h in aqueous solution, as observed by 1H NMR spectroscopy and ESI-MS. The compounds formed adducts with amino acids and proteins through cleavage of the pyridinone ligand. Binding experiments to the nucleosome core particle by means of X-ray crystallography revealed similar reactivity and exclusive binding to histidine moieties of the histone proteins. Preliminary cyclin-dependent kinase 2 (CDK2)/cyclin A kinase inhibitory studies revealed promising activity similar to that of structurally related organometallic compounds. [ABSTRACT FROM AUTHOR]

An unsymmetrically carboxylated platinum(IV) analogue of oxaliplatin was coupled to low-generation polyamidoamine dendrimers (PAMAM) with amino-terminated surfaces [generations two (G-2) and four (G-4)]. 1D and 2D diffusion NMR spectroscopy and high-resolution HPLC-MS/MS were used to characterise the platinum complexes and drug-dendrimer conjugates. The average loads of platinum(IV) complex per dendrimer were determined by inductively coupled plasma MS (ICP-MS), and maximum loads of 38 % (six platinum units per dendrimer molecule) for the smaller G-2 and 34 % (22 platinum units per dendrimer molecule) for G-4 were obtained. As a result of this loading, the average diameters increased from 26 to 34 Å (30 %, G-2) and from 46 to 63 Å (38 %, G-4). The in vitro cytotoxicities of the free platinum(IV) complex, the complex-loaded dendrimers and the free PAMAM analogues G-2 and G-4 were evaluated in the cisplatin-sensitive ovarian cell line CH1/PA1 as well as in rather cisplatin-insensitive colon (SW480) and lung (A549) carcinoma cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Although the free platinum(IV) compound displayed a rather moderate activity, the drug-dendrimer complexes showed load- and size-dependent behaviour with IC50 values down to the low-nanomolar range. In the cisplatin-insensitive cell lines, the benefit of this platinum load primarily consists of added cytostatic rather than cytocidal effects, on the basis of the results from annexin V/PI (PI = propidium iodide) assays for apoptosis/necrosis induction. [ABSTRACT FROM AUTHOR]

Organometallic complexes with thiopyrone-based ligands have shown promising cytotoxic activity in vitro. To investigate the impact of the ligand backbone modification of these biologically active compounds and enhance the solubility in aqueous solution, the (thio)pyrone scaffold was modified via Suzuki–Miyaura coupling reaction and converted into corresponding organometallic Ru(ii) and Rh(iii) complexes. Characterization of the synthesized compounds was carried out by means of 1D and 2D NMR, ESI MS, and also by X-ray diffraction analysis. The stability in aqueous solution was investigated via1H NMR spectroscopy. Due to the close structural resemblance to flavonoids, topoisomerase inhibition, the cytotoxicity in human cancer cell lines as well as ROS generation was investigated by means of the topoisomerase II drug screening assay, the MTT assay and DCFH-DA assay, respectively. [ABSTRACT FROM AUTHOR]

A series of seven diam(m)inebis(carboxylato)dihydroxidoplatinum( IV) and eleven diam(m)inetris(carboxylato)hydroxidoplatinum( IV) complexes with am(m)ine ligands in the trans position was synthesized and characterized by multinuclear ¹H, 13C, 15N, 195Pt NMR spectroscopy. IC50 values for all eighteen substances were determined by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay for three human cancer cell lines. In cisplatin-sensitive CH1(PA-1) cancer cells, diam(m)inebis- (carboxylato)dihydroxidoplatinum(IV) complexes displayed 50% inhibitory concentrations in the micromolar range, whereas for the most lipophilic compounds of the diam(m)- inetris(carboxylato)hydroxidoplatinum(IV) series, promising IC50 values in the nanomolar range were found. [ABSTRACT FROM AUTHOR]

Fine-tuning of the properties of a recently reported 1,3-indandione-based organoruthenium complex is attempted to optimize the stability under physiological conditions. Previous work has shown its capacity of inhibiting topoisomerase IIα; however, fast aquation leads to undesired reactions and ligand cleavage in the blood stream before the tumor tissue is reached. Exchange of the chlorido ligand for six different N-donor ligands resulted in new analogs that were stable at pH 7.4 and 8.5. Only a lowered pH level, as encountered in the extracellular space of the tumor tissue, was capable of aquating the complexes. The 50% inhibitory concentration (IC50) values in three human cancer cell lines differed only slightly, and their dependence on the utilized leaving group was smaller than what would be expected from their differences in cellular accumulation, but in accordance with the very minor variation revealed in measurements of the complexes' lipophilicity. [ABSTRACT FROM AUTHOR]

Metallhaltige Tumortherapeutika werden oft als Prodrugs mit absichtlich geringer Selektivität konzipiert. Dagegen beschreiben S. M. Meier, C. Gerner et al. in der Zuschrift auf S. 8379 die unerwartet große Selektivität eines metallorganischen Ruthenium(II)‐Komplexes, der mit einer Kombination Proteomik‐basierter Methoden, dem Ziel‐Antwort‐Profiling, erhalten wurde. Plectin wurde als zentrale zelluläre Zielverbindung identifiziert. Das Plectin‐Targeting wechselwirkt mit dem Mikrotubulinetzwerk und könnte daher zur Krebsbekämpfung genutzt werden. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Tetracarboxylatoplatinum(IV) complexes are potential anticancer prodrugs. • Novel complexes exhibited IC 50 values down to the low micromolar range. • Fluorinated ligands allowed highly sensitive 19F NMR spectroscopic investigations. • Reduction in cell extracts is different compared to reduction with ascorbic acid. Abstract Tetracarboxylatoplatinum(IV) complexes are interesting representatives of potential anticancer active platinum(IV) drugs. Revealing higher kinetic inertness in comparison to their cytotoxic platinum(II) counterparts, they offer an opportunity to reduce toxic and deactivating side reactions. Platinum(IV) complexes are generally considered as prodrugs, which have to be reduced in order to exert their anticancer activity. Two model complexes, a platinum(II) and platinum(IV) complex featuring two equatorial 3,3,3-trifluoropropanoato (tfpa) and in the case of the latter two axial acetato ligands, were synthesized and characterized in detail by multinuclear (1H, 13C, 15N, 19F, 195Pt) one- and two-dimensional NMR spectroscopy, high-resolution electrospray ionization mass spectrometry, elemental analysis and X-ray diffraction analysis. Cytotoxicity was evaluated in three human cancer cell lines (A549, SW480 and CH1/PA-1) by the MTT colorimetric assay, exhibiting IC 50 values down to the low micromolar range. The fluorinated ligands in equatorial positions allowed detailed and highly sensitive 19F NMR spectroscopic investigations. Besides reaction studies in the presence of small molecules, e.g. ascorbic acid and 5′-GMP, the reduction of the platinum(IV) complex was additionally investigated in two cancer cell extracts deriving from the cell lines SW480 and CH1/PA-1 in order to estimate the intracellular reduction behavior. A significant increase in the rate of reduction in cell extracts (depending on the chosen cell line) compared to the reduction with ascorbic acid could be demonstrated. [ABSTRACT FROM AUTHOR]

By controlled Anderson type rearrangement reactions complexes of the general formula trans-[OsIVCl4(Hazole)2], where Hazole = 1H-pyrazole, 2H-indazole, 1H-imidazole, and 1H-benzimidazole, have been synthesized. Note that 2H-indazole tautomer stabilization in trans-[OsIVCl4(2H-indazole)2] is unprecedented in coordination chemistry of indazole. The metal ion in these compounds possesses the same coordination environment as ruthenium(III) in (H2ind)[RuIIICl4(Hind)2], where Hind = 1H-indazole, (KP1019), an investigational anticancer drug in phase I clinical trials. These osmium(IV) complexes are appropriate precursors for the synthesis of osmium(III) analogues of KP1019. In addition the formation of an adduct of trans-[OsIVCl4(Hpz)2] with cucurbit[7]uril is described. The compounds have been comprehensively characterized by elemental analysis, EI and ESI mass spectrometry, spectroscopy (IR, UV-vis, 1D and 2D NMR), cyclic voltammetry, and X-ray crystallography. Their antiproliferative acitivity in the human cancer cell lines CH1 (ovarian carcinoma), A549 (nonsmall cell lung carcinoma), and SW480 (colon carcinoma) is reported. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, characterization, reactivity and in vitro anticancer activity of a series of RuII–arene complexes with carbohydrate-derived phosphite and biscarboxylato co-ligands are reported. The compounds were characterized by NMR spectroscopy and electrospray ionization (ESI) mass spectrometry, and the molecular structures of oxalato(η6-p-cymene)(3,5,6-bicyclophosphite-1,2-O-isopropylidene-α-D-glucofuranoside)ruthenium(II) and oxalato(η6-p-cymene)(3,5,6-bicyclophosphite-1,2-O-cyclohexylidene-α-D-glucofuranoside)ruthenium(II) were determined by X-ray diffraction analysis. In contrast to their dichlorido counterparts, the biscarboxylato complexes did not exhibit significant reactivity towards biomolecules, such as cysteine, methionine, ubiquitin or the DNA model 5′-GMP, and resist hydrolysis; no hydrolytic species were detected by 1H and 31P{1H} NMR spectroscopy over several days. These structural alterations led to a decrease in the tumor-inhibiting potency of the compounds in human cancer cell lines. [ABSTRACT FROM AUTHOR]

• Synthesis of organometallic selenopyridone complexes. • Dimer formation in aqueous solution. • Stability investigations. • Determination of cytotoxic potential. A series of seven piano–stool complexes featuring selenopyridones as Se,O -chelating ligands was synthesized and characterized. The resulting complexes bear either a p -cym Ru/Os or Cp* Rh/Ir fragment attached to a bidentate selenopyridone ligand. In accordance with recent findings for closely related thiopyridone complexes, dimerization in protic solvents was observed for these compounds. However, these organometallics revealed surprises regarding stability, as well as biological activity. In contrast to analogous thiopyridone organometallics, some of the synthesized complexes were prone to quick ligand dissociation. However, four examples exhibited sufficient stability in aqueous solution to justify further biological investigations. Therefore, MTT assays were carried out for the stable derivatives in three different cancer cell lines. Cytotoxicity trends based on the utilized metal center of the organometallic moiety were observed and compared to the corresponding thio-analogs. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of two novel cisplatin- alkylating agents conjugates. Combining a platinum based cytostatic agent with a sterically demanding alkylating agent could potentially induce further DNA damage, block cell repair mechanisms and keep the substrate active against resistant tumor cell lines. The 3-chloropiperidines utilized as ligands in this work are cyclic representatives of the N-mustard family and were not able to coordinate platinum on their own. The introduction of a second coordination site, in form of a pyridine moiety, led to the isolation of the desired conjugates. They were characterized with HRMS, CHN-analyses and XRD. We concluded this work by examining the cytotoxicity of the ligands and the obtained complexes with MTT assays in human cancer cell lines. While the ligands showed hardly any activity, the novel conjugates both displayed a high antiproliferative and cytotoxic potency in a panel of three cell lines. Moreover, both complexes were able to largely circumvent the acquired cisplatin resistance of A2780cisR ovarian cancer cells, both in the MTT assay and a flow-cytometric apoptosis assay., (© 2024 The Author(s). ChemBioChem published by Wiley-VCH GmbH.)

In this contribution we report the synthesis, characterization and in vitro anticancer activity of novel cyclometalated 4-phenylthiazole-derived ruthenium(II) (2a-e) and osmium(II) (3a-e) complexes. Formation and sufficient purity of the complexes were unambigiously confirmed by 1 H-, 13 C- and 2D-NMR techniques, X-ray diffractometry, HRMS and elemental analysis. The binding preferences of these cyclometalates to selected amino acids and to DNA models including G-quadruplex structures were analyzed. Additionally, their stability and behaviour in aqueous solutions was determined by UV-Vis spectroscopy. Their cellular accumulation, their ability of inducing apoptosis, as well as their interference in the cell cycle were studied in SW480 colon cancer cells. The anticancer potencies were investigated in three human cancer cell lines and revealed IC 50 values in the low micromolar range, in contrast to the biologically inactive ligands.

The reaction of (1 R ,2 R )-(cyclohexane-1,2-diamine)dichloridoplatinum(II) with maleic acid unexpectedly resulted in the formation of an organometallic platinum(II) complex featuring a C , O -coordinating ligand. Additionally, a small series of close derivatives with increasing lipophilicity was synthesized. All complexes were fully characterized by multinuclear one- and two-dimensional ( 1 H, 13 C, 15 N, and 195 Pt) NMR spectroscopy, high resolution mass spectrometry, and in one case by X-ray diffraction. The lipophilicity and the impact on the DNA secondary structure as well as the cytotoxic properties in three human cancer cell lines (A549, SW480, and CH1/PA-1) were investigated. Unexpectedly, no clear-cut trend in cytotoxicity was observed with increasing lipophilicity. Also unexpectedly, the complexes showed only a low potential to inhibit cancer cell growth and no sign of interaction with DNA, in sharp contrast to the parent drug oxaliplatin, which seems to be caused by the low reactivity of the investigated compounds.

A series of six highly lipophilic Cp-substituted molybdenocenes bearing different bioactive chelating ligands was synthesized and characterized by NMR spectroscopy, mass spectrometry and X-ray crystallography. In vitro experiments showed a greatly increased cytotoxic potency when compared to the non-Cp-substituted counterparts. In vivo experiments performed with the dichlorido precursor, (Ph 2 C-Cp) 2 MoCl 2 and the in vitro most active complex, containing the thioflavone ligand, showed an inhibition of tumour growth. Proteomic studies on the same two compounds demonstrated a significant regulation of tubulin-associated and mitochondrial inner membrane proteins for both compounds and a strong metabolic effect of the thioflavone containing complex., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The main purpose of this study was to synthesize a new set of naphthoquinone-based ruthenium(II) arene complexes and to develop an understanding of their mode of action. This study systematically reviews the steps of synthesis, aiming to provide a simplified approach using microwave irradiation. The chemical structures and the physicochemical properties of this novel group of compounds were examined by 1 H-NMR and 13 C-NMR spectroscopy, X-ray diffractometry, HPLC-MS and supporting DFT calculations. Several aspects of the biological activity were investigated in vitro, including short- and long-term cytotoxicity tests, cellular accumulation studies, detection of reactive oxygen species generation, apoptosis induction and NAD(P)H:quinone oxidoreductase 1 (NQO1) activity as well as cell cycle analysis in A549, CH1/PA-1, and SW480 cancer cells. Furthermore, the DNA interaction ability was studied in a cell-free assay. A positive correlation was found between cytotoxicity, lipophilicity and cellular accumulation of the tested complexes, and the results offer some important insights into the effects of the arene. The most obvious finding to emerge from this study is that the usually very chemosensitive CH1/PA-1 teratocarcinoma cells showed resistance to these phthiocol-based organometallics in comparison to the usually less chemosensitive SW480 colon carcinoma cells, which pilot experiments suggest as being related to NQO1 activity.

A series of nine Ru II arene complexes bearing tridentate naphthoquinone-based N , O , O -ligands was synthesized and characterized. Aqueous stability and their hydrolysis mechanism were investigated via UV/vis photometry, HPLC-MS, and density functional theory calculations. Substituents with a positive inductive effect improved their stability at physiological pH (7.4) intensely, whereas substituents such as halogens accelerated hydrolysis and formation of dimeric pyrazolate and hydroxido bridged dimers. The observed cytotoxic profile is unusual, as complexes exhibited much higher cytotoxicity in SW480 colon cancer cells than in the broadly chemo- (incl. platinum-) sensitive CH1/PA-1 teratocarcinoma cells. This activity pattern as well as reduced or slightly enhanced ROS generation and the lack of DNA interactions indicate a mode of action different from established or previously investigated classes of metallodrugs.