Synthesis, structures and in vitro cytotoxicity of some platinum(II) complexes containing thiocarbamate esters

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

Synthesis, characterization and biological investigation of platinum(ii) complexes with asparagusic acid derivatives as ligands

After more than 50 years of platinum-based anticancer research only three compounds are in clinical use worldwide. The use of the well-known lead compound of this class of anticancer agents, cisplatin, is limited by its side effects and varying resistance mechanisms. Therefore, we report on platinum(ii) compounds with asparagusic acid derivatives as ligands which show interesting anticancer results on cisplatin resistant cell lines.

Anti-tumour active gold(i), palladium(ii) and ruthenium(ii) complexes with thio- and selenoureato ligands: a comparative study

We report the results of a comparative study of the biological activity of a series of gold(i), palladium(ii) and ruthenium(ii) complexes containing deprotonated thio- and selenoureato ligands. A library of compounds was prepared and characterised by spectroscopic methods and the solid-state structures of several derivatives were determined by single crystal X-ray diffraction. The in vitro activity of these compounds was evaluated in mammary and ovarian carcinoma, acute lymphatic and acute and chronic myeloid leukemia cell lines. At lower concentrations Ru- and Pd-containing compounds displayed stronger anti-cancer effects than the gold compounds. In all cases, the selenium derivatives proved to be more active than the corresponding sulfur compounds.

Benzothiazole-Based Cycloplatinated Chromophores: Synthetic, Optical, and Biological Studies

Cycloplatinated complexes based on 2-(4-substituted)benzothiazole ligands of type [Pt(R-PBT-κC,N)Cl(L)] (PBT=2-phenylbenzothiazole; R=Br (1), Me₂ N (2); L=dimethyl sulfoxide (DMSO; a), 1,3,5- triaza-7-phosphaadamantane (PTA; b), triphenylphosphine 3,3',3''-trisulfonate (TPPTS; c)) and [Pt(Br-PBT-κC)Cl(PTA)₂ ] (3) are presented. On the basis of the photophysical data and time-dependent (TD)-DFT calculations (1 a and 2 a), the low-lying transitions (absorption and emission) were associated with ligand-center (LC) charge transfer, with minor metal-to-ligand charge transfer (MLCT), and intraligand charge transfer (ILCT) [Me₂ N-PBT→PBT] excited states, respectively. Simultaneous fluorescence/phosphorescence bands were found in fluid solutions (and also in the solid state for 2 a), which become dominated by triplet emission bands in rigid media at 77 K. The effect of the concentration on emissive behavior of 2 a, b indicated the occurrence of aggregation-induced luminescence properties related to the occurrence of metal-metal and π⋅⋅⋅π interactions, which are more enhanced in 2 a because of the less bulky DMSO ligand. The behavior of 2 a toward para-toluenesulfonic acid (PTSA) in aerated acetonitrile and to hydrogen chloride gas in the solid state has been evaluated, thus showing a clear reversible change between the ¹ ILCT and ³ LC/³ MLCT states due to protonation of the NMe₂ group (theoretical calculations on 2 a-H⁺ ). Solid 2 a undergoes a surprising oxidation of the Pt^II center to Pt^IV with concomitant deoxygenation of DMSO, under prolonged reaction with hydrogen chloride gas to afford the Pt^IV /dimethyl sulfide complex (mer-[Pt(Me₂ N-PBT-κC,N)Cl₃ (SMe₂ )]; mer-4), which evolves in solution to fac-4, as confirmed by X-ray studies. Cytotoxic activity studies on A549 and HeLa cell lines indicated cytotoxic activity of 1 b and 2 a, b. In addition, fluorescent cell microscopy revealed cytoplasmic staining, more visible in perinuclear areas. Inhibition of tubulin polymerization by 1 b in both cells is presented as a preliminary mechanism of its cytotoxic action.

Organomonophosphines in PtP2S2 derivatives: structural aspects

In this review, the structural parameters of almost 130 monomeric Pt(II) coordination complexes with the inner coordination sphere of PtP

RNA silencing of integrin-linked kinase increases the sensitivity of the A549 lung cancer cell line to cisplatin and promotes its apoptosis

The expression of integrin-linked kinase (ILK) has been reported to be involved in the regulation of integrin-mediated processes, including cancer cell proliferation, migration and invasion. Previous studies have demonstrated that inhibition of ILK may be an underlying approach for treating cancer. However, whether the knock down of ILK affects growth and apoptosis of lung cancer cells remains to be elucidated. Importantly, whether downregulation of ILK increases the sensitivity of lung cancer cells to cisplatin and amplifies cell apoptosis also remains to be elucidated. In the present study, ILK downregulation was mediated by lentivirus-mediated RNA interference. The expression levels of associated genes were determined by reverse-transcription quantitative polymerase chain reaction and western blotting. Cell proliferation was evaluated using a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and clone formation assay. The cell cycle and apoptosis were analyzed using flow cytometry. The current data revealed that lentivirus-mediated ILK gene silencing alone inhibited A549 cell proliferation and promotes cell cycle arrest, however, had no detectable effect on cell apoptosis. However, combined treatment with lentivirus-mediated ILK interference and cisplatin chemotherapy induced significantly more cell apoptosis than mono-chemotherapy or knockdown. The increased cell apoptosis and proliferation inhibition were attributed to abnormal downstream protein expression of ILK, including phospho-glycogen synthase kinase 3β, p-AKT, activator protein-1, β-catenin, cyclin D1 and matrix metalloproteinase-9. ILK inhibition may suppress the proliferation of A549 and increase A549 sensitivity to cisplatin. The combined treatment of ILK gene knockdown and chemotherapy has the potential to improve anticancer efficacy.

Investigation of putative arene-C-H···π(quasi-chelate ring) interactions in copper(I) crystal structures

Evidence for C-H···π(CuCl···HNCS) interactions, i.e. C-H···π(quasi-chelate ring) where a six-membered quasi-chelate ring is closed by an N-H···Cl hydrogen bond, is presented based on crystal structure analyses of (Ph3P)2Cu[ROC(=S)N(H)Ph]Cl. Similar intramolecular interactions are identified in related literature structures. Calculations suggest that the energy of attraction provided by such interactions approximates 3.5 kcal mol(-1).

The influence of R substituents in triphenylphosphinegold(I) carbonimidothioates, Ph3PAu[SC(OR)=NPh] (R=Me, Et and iPr), upon in vitro cytotoxicity against the HT-29 colon cancer cell line and upon apoptotic pathways

The Ph3PAu[SC(OR)=NPh], R=Me (1), Et (2) and iPr (3), compounds are significantly cytotoxic to the HT-29 cancer cell line with 1 being the most active. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis is demonstrated and both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. Compound 1 activates the p73 gene, whereas each of 2 and 3 activates the p53 gene. An additional apoptotic mechanism is exhibited by 2, that is, via the JNK/MAP pathway.

Synthesis, structures and anti-malaria activity of some gold(I) phosphine complexes containing seleno- and thiosemicarbazonato ligands

A series of both mono- and dinuclear gold(I) phosphine complexes containing monoanionic seleno- and thiosemicarbazones as ligands were prepared and fully characterized by spectroscopic methods and, in some cases, by single crystal X-ray diffraction. The in vitro anti-malaria activity of some of these compounds was investigated in chloroquine sensitive strains of Plasmodium falciparum. The IC(50) results show that the sulfur containing compounds exhibit activity similar to that of chloroquine, whilst the selenium derivatives display only moderate anti-malaria activity.

Platinum(II) oxalato complexes with adenine-based carrier ligands showing significant in vitro antitumor activity

[Pt(L)(2)(ox)] (1), [Pt(2-OMeL)(2)(ox)] (2), [Pt(3-OMeL)(2)(ox)] (3), [Pt(2,3-diOMeL)(2)(ox)] (4), [Pt(2,4-diOMeL)(2)(ox)] (5), [Pt(3,4-diOMeL)(2)(ox)] (6) and [Pt(3,5-diOMeL)(2)(ox)].4H(2)O (7) platinum(II) oxalato (ox) complexes were synthesized using the reaction of potassium bis(oxalato)platinate(II) dihydrate with 2-chloro-N6-(benzyl)-9-isopropyladenine or its benzyl-substituted analogues (nL). The complexes 1-7, which represent the first platinum(II) oxalato complexes involving adenine-based ligands, were fully characterized by various physical methods including multinuclear and two dimensional NMR spectroscopy. A single-crystal X-ray analysis of [Pt(2,4-diOMeL)(2)(ox)].2DMF (5.2DMF; DMF=N,N'-dimethylformamide), proved the slightly distorted square-planar geometry in the vicinity of the Pt(II) ion with one bidentate-coordinated oxalate dianion and two adenine derivatives (nL) coordinated to the Pt(II) centre through the N7 atom of an adenine moiety, thereby giving a PtN(2)O(2) donor set. In vitro cytotoxicity of the prepared complexes was tested by an MTT assay against osteosarcoma (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines. The best results were achieved for the complexes 2 and 5 in the case of both cell lines, whose IC(50) values equalled 3.6+/-1.0, and 4.3+/-2.1microM (for 2), and 5.4+/-3.8, and 3.6+/-2.1microM (for 5), respectively. The IC(50) equals 9.2+/-1.5microM against MCF7 cells in the case of 1. The in vitro cytotoxicity of the mentioned complexes significantly exceeded commercially used platinum-based anticancer drugs cisplatin (34.2+/-6.4microM and 19.6+/-4.3microM) and oxaliplatin (>50.0microM for both cancer cell lines).

Synthesis and biological studies of some gold(I) complexes containing functionalised alkynes

The propargyl ethers 7-chloro-(4-propargyloxy)quinoline, 1-propargyloxynaphthalene and 2-propargyloxybenzophenone react with [AuCl(PPh(3))] in the presence of KOH to give the gold(I) alkynyl complexes [Au(C[triple bond]COCH(2)Ar)(PPh(3))] in good yields. The compounds were fully characterised by spectroscopic methods and were subsequently examined for their biological activity against four tumour cell lines as well as their activity against Plasmodium falciparum, the parasite responsible for malaria. The compounds show antiproliferative effects in human cancer cells with IC(50) values ranging from 0.4-12 microM.