👤 Silva RS

Background

Melanoma is the most aggressive and lethal skin cancer that affects thousands of people worldwide. Ruthenium complexes have shown promising results as cancer chemotherapeutics, offering several advantages over platinum drugs, such as potent efficacy, low toxicity, and less drug resistance. Additionally, anthraquinone derivatives have broad therapeutic applications, including melanoma.

Objectives

Thus, two new ruthenium complexes with 1-hydroxy-9,10-anthraquinone were obtained: trans-[Ru(HQ)(PPh₃)₂(bipy)]PF₆ (1) and cis-[RuCl₂(HQ)(dppb)] (2), where HQ = 1-hydroxy-9,10-anthraquinone, PPh₃ = triphenylphospine, bipy = 2,2'-bipyridine, PF₆ = hexafluorophosphate, and dppb = 1,4-bis(diphenylphosphine)butane.

Methods

The complexes were characterized by infrared (IR), UV-vis, ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopies, molar conductivity, cyclic voltammetry, and elemental analysis. Furthermore, density functional theory (DFT) calculations were performed.

Results

Compound (2) was determined by single-crystal X-ray diffraction, which confirms the bidentate coordination mode of HQ through the carbonyl and phenolate oxygens. Additionally, DNA-binding experiments yielded constants of 10⁵ M^-1 (Kb = 6.93 × 10⁵ for (1) and 1.60 × 10⁵ for (2)) and demonstrate that both complexes can interact with DNA through intercalation, electrostatic attraction, or hydrogen bonding.

Conclusions

The cytotoxicity profiles of the compounds were evaluated in human melanoma cell lines (SK-MEL-147, CHL-1, and WM1366), revealing greater cytotoxic activity for (1) on the CHL-1 cell line with an IC₅₀ of 14.50 ± 1.09 µM. Subsequent studies showed that (1) inhibits the proliferation of CHL-1 cells and induces apoptosis, associated at least in part with the pro-oxidant effect and cell cycle arrest at the G1/S transition. Show less

Acute myeloid leukemia (AML) is a lethal hematologic malignancy caused by leukemic blasts that fail to mature normally. AML has a high relapse rate, primarily due to a small subset known as leukemic stem cells (LSCs). In this work, we investigated the ability of a Ru(II)-thymine complex (RTC) with the formula [Ru(PPh₃)₂(Thy)(bipy)]PF₆ (where PPh₃ = triphenylphosphine, Thy = thymine, and bipy = 2,2'-bipyridine) to suppress AML LSCs. RTC exhibited potent cytotoxicity toward both solid and hematologic malignancies and suppressed primary AML LSCs, as observed by the reduction in the CD34 +CD38- cell population. In the AML cell line KG-1a, which has an LSC-like population, RTC reduced the number of CD34 + and CD123 + cells. A reduction in leukemic blasts was detected in the bone marrow of RTC-treated NSG mice bearing KG-1a xenografts. Increased DNA fragmentation, YO-PRO-1 staining, active caspase-3 and cleaved PARP (Asp 214) levels, and mitochondrial superoxide levels were detected in RTC-treated KG-1a cells. The pancaspase inhibitor Z-VAD-(OMe)-FMK, but not the antioxidant N-acetylcysteine, partially prevented RTC-induced cell death in KG-1a cells, indicating that RTC induces caspase-mediated apoptosis in KG-1a cells via an oxidative stress-independent pathway. In molecular mechanism studies, transcripts of the NF-κB inhibitor NFKBIA were upregulated, and the level of NF-κB p65 phosphorylated at the Ser529 residue was reduced in RTC-treated KG-1a cells, indicating that RTC may inhibit NF-κB signaling. Overall, these results indicate the anti-AML potential of RTC in AML LSCs via the suppression of NF-κB signaling. Show less

Cancer stem cells (CSCs) are defined as a rare population of cancer cells related to tumor initiation and maintenance. These cells are primarily responsible for tumor growth, invasion, metastasis, recurrence, and resistance to chemotherapy. In this paper, we demonstrated the ability of Ru(II)-based complexes containing 2-thiouracil derivatives with the chemical formulas trans-[Ru(2TU)(PPh₃)₂(bipy)]PF₆ (1) and trans-[Ru(6m2TU)(PPh₃)₂(bipy)]PF₆ (2) (where 2TU = 2-thiouracil and 6m2TU = 6-methyl-2-thiouracil) to suppress liver CSCs by targeting NF-κB and Akt/mTOR signaling. Complexes 1 and 2 displayed potent cytotoxic effects on cancer cell lines and suppressed liver CSCs from HepG2 cells. Increased phosphatidylserine exposure, loss of mitochondrial transmembrane potential, increased PARP (Asp214) cleavage, DNA fragmentation, chromatin condensation and cytoplasmic shrinkage were detected in HepG2 cells treated with these complexes. Mechanistically, complexes 1 and 2 target NF-κB and Akt/mTOR signaling in HepG2 cells. Cell motility inhibition was also detected in HepG2 cells treated with these complexes. Complexes 1 and 2 also inhibited tumor progression in mice with HepG2 cell xenografts and exhibited tolerable systemic toxicity. Taken together, these results indicate that these complexes are new anti-HCC drug candidates that can suppress liver CSCs. Show less

Title: New ruthenium(II) complexes with cyclic thio- and semicarbazone: evaluation of cytotoxicity and effects on cell migration and apoptosis of lung cancer cells. Abstract: We describe the synthesis, physicochemical characterization, and in vitro antitumor assays of four novel analogous ruthenium(II) complexes with general formula cis-[RuII(N-L)(P-P)2]PF6, where P-P = bis(diphenylphosphine)methane (dppm, in complexes 1 and 2) or bis(diphenylphosphine)ethane (dppe, in complexes 3 and 4) and N-L = 5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione (Btsc, in complexes 1 and 3) or 5,6-diphenyltriazine-3-one (Bsc, in complexes 2 and 4). The data were consistent with cis arrangement of the biphosphine ligands. For the Btsc and Bsc ligands, the data pointed to monoanionic bidentate coordination to ruthenium(II) through N,S and N,O, respectively. Single-crystal X-ray diffraction showed that complex 1 crystallized in the monoclinic system, space group P21/c. Determination of the cytotoxicity profiles of complexes 1-4 gave SI values ranging from 1.19 to 3.50 against the human lung adenocarcinoma cell line A549 and the non-tumor lung cell line MRC-5. Although the molecular docking studies suggested that the interaction between DNA and complex 4 was energetically favorable, the experimental results showed that they interacted weakly. Overall, our results demonstrated that these novel ruthenium(II) complexes have interesting in vitro antitumor potential and this study may contribute to further studies in medicinal inorganic chemistry. Show less

[Ru(5-FU)(PPh₃)₂(bipy)]PF₆ (Ru/5-FU) is a novel ruthenium complex with 5-fluorouracil with promising potential against colorectal cancer (CRC). In the present study, we investigated the molecular mechanism of Ru/5-FU action in HCT116 CRC cells. Ru/5-FU exhibited potent cytotoxicity on a panel of cancer cell lines and on primary cancer cells and induced apoptosis in HCT116 CRC cells. Ru/5-FU reduced AKT1 gene transcripts, as well as the expression of Akt1 and Akt (pS473) and downstream Akt proteins mTOR (pS2448), S6 (pS235/pS236), 4EBP1 (pT36/pT45), GSK-3β (pS9) and NF-κB p65 (pS529), but not Akt upstream proteins Hsp90 and PI3K p85/p55 (pT458/pT199), indicating an inhibitory action of Akt/mTOR signaling. Ru/5-FU increased LC3B expression and reduced p62/SQSTM1 levels, indicating autophagy induction. Curiously, the autophagy inhibitors 3-methyladenine and chloroquine increased Ru/5-FU-induced cell death, indicating an induction of cytoprotective autophagy by this compound. Ru/5-FU also reduced clonogenic survival, as well as the percentage of CD133+ cells and colonosphere formation, indicating that Ru/5-FU can suppress stem cells in HCT116 cells. Ru/5-FU inhibited cell migration and invasion in wound healing assays and Transwell cell invasion assays, along with a reduction in vimentin expression and an increase in E-cadherin levels, indicating that Ru/5-FU can interfere with epithelial-mesenchymal transition. Ru/5-FU also inhibited in vivo HCT116 cell development and experimental lung metastases in mouse xenograft models. Altogether, these results indicate that Ru/5-FU is an anti-CRC chemotherapy drug candidate with the ability to suppress stemness in CRC cells by inhibiting Akt/mTOR signaling. Show less

We report here on three new ruthenium(II) complexes, [Ru(DPEPhos)(mtz)(bipy)]PF₆ (Ru1), [Ru(DPEPhos)(mmi)(bipy)]PF₆ (Ru2) and [Ru(DPEPhos)(dmp)(bipy)]PF₆ (Ru3). DPEPhos = bis-[(2-diphenylphosphino)phenyl]ether, mtz = 2-mercapto-2-thiazoline, mmi = 2-mercapto-1-methylimidazole, dmp = 4,6-diamino-2-mercaptopyrimidine and bipy = 2,2'-bipyridine. The compounds were characterized by several spectroscopic techniques, and the molecular structure of Ru1 complex was determined by single-crystal X-ray diffraction. The cytotoxicity of Ru1 - Ru3 complexes were tested against the A549 (human lung) and the MDA-MB-231 (human breast) cancer cell lines and against MRC-5 (non-tumor lung) and MCF-10A (non-tumor breast) cell lines through the MTT assay. All three complexes are cytotoxic against the cell lines studied, with IC₅₀ values lower than those found for the cisplatin. Among them, the Ru2 complex has shown the best selectivity against MDA-MB-231 cancer cell lines, with an IC₅₀ value 12 times lower than that on MCF-10A. The complex Ru2 was capable to induce changes in MDA-MB-231 cells morphology, with loss of cellular adhesion, inhibited colony formation and induce an accumulation of cells at the sub-G1 phase, with an increase in S-phase and decrease of cells at G2 phase. Viscosity, electrochemical and Hoechst 33258 displacement experiments for Ru1 - Ru3 complexes with calf thymus DNA (CT-DNA) showed an electrostatic and groove binding mode of interaction. Additionally, the complexes interact with the protein Human Serum Albumin (HSA) by static mechanism. The negative values for ΔH and ΔS indicate that van der Waals forces and hydrogen bonding may occurs between the complexes and HSA. Therefore, this class of complexes are promising anticancer candidates and may be selected to further detailed studies. Show less

In this work we present the synthesis and characterization of six new ruthenium compounds with general formulae [Ru(L)(dppb)(bipy)]PF₆ and [Ru(L)(dppe)₂]PF₆ where L = salicylic acid (Sal), 4-aminosalicylic acid (AmSal) or 2,4-dihydroxybenzoic acid (DiSal), dppb = 1,4-bis(diphenylphosphino)butane, dppe = 1,2-bis(diphenylphosphino)ethane and bipy = 2,2'-bipyridine. The complexes were characterized by elemental analysis, molar conductivity, cyclic voltammetry, NMR, UV-vis and IR spectroscopies, and two by X-ray crystallography. The ³¹P{¹H} NMR spectra of the complexes with the general formula [Ru(L)(dppe)₂]PF₆ showed that the phosphorus signals are solvent-dependent. Aprotic solvents, which form strong hydrogen bonds with the complexes, inhibit the free rotation of the salicylic acid-based, modifying the diphosphine cone angles, leading to distortion of the phosphorus signals in the NMR spectra. The cytotoxicity of the complexes was evaluated in MCF-7, MDA-MB-231, SKBR3 human breast tumor cells, and MCF-10 non-tumor cell lines. The complexes with the structural formula [Ru(L)(dppe)₂]PF₆ were the most cytotoxic, and the complex [Ru(AmSal)(dppe)₂]PF₆ with L = 4-aminosalicylic acid ligand was the most selective for the MDA-MB-231 cell line. This complex interacts with the transferrin and induces apoptosis through the intrinsic pathway, as demonstrated by increased levels of proteins involved in apoptotic cell death. Show less

Title: Ruthenium(II)-diphosphine complexes containing acylthiourea ligands are effective against lung and breast cancers. Abstract: We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF6, where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2'-bipyridine, and O,S = N,N-dimethyl-N'-(benzoyl)thiourea (1), N,N-dimethyl-N'-(furoyl)thiourea (2), and N,N-dimethyl-N'-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC50 values lie in the micromolar range (0.07-0.70 μM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1-3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment. Show less

Background

Breast cancer is one of the most common types among women. Its incidence progressively increases with age, especially after age 50. Platinum compounds are not efficient in the treatment of breast cancer, highlighting the use of other metals for the development of new chemotherapeutic agents.

Objective

This paper aims to obtain three new ruthenium compounds that incorporate sulfur amino acids in their structures and to investigate their cytotoxic activity in breast tumor cell lines.

Methods

Complexes with general formula [Ru(AA)(dppb)(bipy)] (complexes 1 and 2) or [Ru(AA)(dppb) (bipy)]PF6 (complex 3), where AA = L-cysteinate (1), D-penicillaminate (2), and L-deoxyalliinate (3), dppb = 1,4-bis(diphenylphosphino)butane and 2,2´-bipyridine, were obtained from the cis-[RuCl₂(dppb)(bipy)] precursor. The cytotoxicity of the complexes on MDA-MB-231 (triple negative human breast cancer); MCF-7 (double positive human breast cancer) and V79 (hamster lung fibroblast) was performed by the MTT (4,5- dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide) method. The control agent was the cisplatin, which is a commercially available drug for cancer treatment.

Results

In complexes (1) and (2), the ligands are coordinated to the metal center by nitrogen and sulfur atoms, while in complex (3), coordination is through the oxygen and nitrogen atoms. These suggestions are based on the infrared and 31P{1H} NMR data. For complexes (1) and (2), their X-ray structures were determined confirming this suggestion. The three complexes are stable in a mixture of DMSO (80%) and biological medium (20%) for at least 48h and presented cytotoxicity against the MDA-MB-231 and MCF-7 tumor cells with reasonable selectivity indexes.

Conclusion

Our work demonstrated that ruthenium complexes containing sulfur amino acids, bipyridines and bisphosphines showed cytotoxicity against the MDA-MB-231 and MCF-7 cancer cell lines, in vitro, and that they interact weakly with the DNA (Deoxyribonucleic Acid) and the HSA (Human Serum Albumin) biomolecules. Show less

Metal complexes based on ruthenium have established excellent activity with less toxicity and great selectivity for tumor cells. This study aims to assess the anticancer potential of ruthenium(II)/allopurinol complexes called [RuCl₂(allo)₂(PPh₃)₂] (1) and [RuCl₂(allo)₂(dppb)] (2), where allo means allopurinol, PPh₃ is triphenylphosphine and dppb, 1,4-bis(diphenylphosphino)butane. The complexes were synthesized and characterized by elemental analysis, IR, UV-Vis and NMR spectroscopies, cyclic voltammetry, molar conductance measurements, as well as the X-ray crystallographic analysis of complex 2. The antitumor effects of compounds were determined by cytotoxic activity and cellular and molecular responses to cell death mechanisms. Complex 2 showed good antitumor profile prospects because in addition to its cytotoxicity, it causes cell cycle arrest, induction of DNA damage, morphological and biochemical alterations in the cells. Moreover, complex 2 induces cell death by p53-mediated apoptosis, caspase activation, increased Beclin-1 levels and decreased ROS levels. Therefore, complex 2 can be considered a suitable compound in antitumor treatment due to its cytotoxic mechanism. Show less

Photoactivated chemotherapy (PACT) is an emerging strategy for targeted cancer therapy. Strained Ru complexes with pseudo-octahedral geometry may undergo photo-induced ligand dissociation, forming aquated photoproducts that are significantly more cytotoxic compared to the precursor complex. The complexes investigated were the strained complex [Ru(bpy)₂BC]Cl₂ (where bpy = 2,2'-bipyridine and BC = bathocuproine) and its unstrained control [Ru(bpy)₂phen]Cl₂ (where phen = 1,10-phenanthroline). The uptake of [Ru(bpy)₂BC]Cl₂, assessed by ICP/MS, started immediately post-incubation and plateaued after 24 h. Active transport was found as the main mode of intracellular transport. Cell viability assays on A375 cells indicated a mean phototoxicity index of 340-fold, and the effect was shown to be primarily mediated by the aquated photoproducts rather than the dissociating ligands. A significant increase in ROS production and DNA damage was also observed. Flow cytometry confirmed the induction of early apoptosis at 48 h that proceeds to late apoptosis/necrosis by 72 h post-treatment. Western blot analysis of pro- and anti-apoptotic proteins revealed that apoptosis was mediated through an interplay between the intrinsic and extrinsic pathways, as well as autophagy and via inhibition of the MAPK and PI3K pathways. In conclusion, this study demonstrates that [Ru(bpy)₂BC]Cl₂ is a multi-mechanistic PACT drug which exhibits promising anticancer potential. Show less

Ruthenium(II) complexes (Ru1-Ru5), with the general formula [Ru(N-S)(dppe)₂]PF₆, bearing two 1,2-bis(diphenylphosphino)ethane (dppe) ligands and a series of mercapto ligands (N-S), have been developed. The combination of these ligands in the complexes endowed hydrophobic species with high cytotoxic activity against five cancer cell lines. For the A549 (lung) and MDA-MB-231 (breast) cancer cell lines, the IC₅₀ values of the complexes were 288- to 14-fold lower when compared to cisplatin. Furthermore, the complexes were selective for the A549 and MDA-MB-231 cancer cell lines compared to the MRC-5 nontumor cell line. The multitarget character of the complexes was investigated by using calf thymus DNA (CT DNA), human serum albumin, and human topoisomerase IB (hTopIB). The complexes potently inhibited hTopIB. In particular, complex [Ru(dmp)(dppe)₂]PF₆ (Ru3), bearing the 4,6-diamino-2-mercaptopyrimidine (dmp) ligand, effectively inhibited hTopIB by acting on both the cleavage and religation steps of the catalytic cycle of this enzyme. Molecular docking showed that the Ru1-Ru5 complexes have binding affinity by active sites on the hTopI and hTopI-DNA, mainly via π-alkyl and alkyl hydrophobic interactions, as well as through hydrogen bonds. Complex Ru3 displayed significant antitumor activity against murine melanoma in mouse xenograph models, but this complex did not damage DNA, as revealed by Ames and micronucleus tests. Show less

The number of cancer cases continues to increase worldwide, and unfortunately the main systemic treatments available have numerous of side effects. Ruthenium complexes have shown to be promising chemotherapeutic agents, since they present low toxicity and are more selective for tumor tissues. We report the synthesis, characterization and biological properties of two new ruthenium (II) complexes containing Lapachol and Lawsone as ligands: (1) [Ru(Law)(dppb)(phen)]PF₆ and (2) [Ru(Lap)(dppb)(phen)]PF₆, where Law = Lawsone, Lap = Lapachol, dppb = 1,4-bis(diphenylphosphine)butane and phen = 1,10-phenanthroline. The ability of the complexes (1) and (2) to interact with CT-DNA (Calf Thymus) was investigated, and the results indicate that the complexes have shown a weak interaction with this macromolecule. Complexes (1) and (2) showed a moderate interaction with BSA, via a spontaneous process with the involvement of van der Waals and hydrogen bond interactions. Both complexes were tested against human lung cancer cell lines, chronic human myeloid leukemia, murine melanoma and human cervical and non-tumoral murine fibroblast adenocarcinoma, human lung fibroblasts and monkey kidney epithelia. The potential for cytotoxicity was tested out using the MTT assay and the neutral red test, to calculate inhibitory concentrations (IC50) and selectivity indices (IS). Both complexes showed a higher selectivity index of 1.17 and 10.91, respectively, for the HeLa tumor line. Studies of toxicological evaluation, using the micronucleus test and the comet assay against non-tumor cells, as well as an assessment of the potential for acute toxicity and neurotoxicity in zebrafish (Danio rerio). In the in vitro micronucleus test, complex (1) showed the least genotoxic potential, and in the in vitro comet assay both compounds had revealed a genotoxic potential at 0.5 and 1.0 mg L^-1, with no difference between 24 h and 48 h exposure times. In the acute toxicity tests on zebrafish embryos, complex (1) showed sublethal effects such as decreased blood circulation and heartbeat rate, which were less pronounced than with complex (2). In contrast to complex 2, which caused lethality even before 48h, complex (1) did not cause the death of the embryos at concentrations up to (2.0 mg L^-1). Complex (2) also lead to a delay in the embryo. Cell based in vitro methods thus proved able to provide specific toxicological data, allowing a significant reduction in ∖animal experimentation. Given that in vitro tests cannot completely replace animal tests, the use of less advanced developmental stages such as zebrafish embryos, which - at least in the European Union - are not regarded protected, could be shown to be an excellent alternative for testing with, e.g., mammals. Show less

The preparation of two new Ru(II)/diphosphine complexes containing Lapachol (Lap) and Lawsone (Law): (1) [Ru(Lap)(dppm)₂]PF₆ and (2) [Ru(Law)(dppm)₂]PF₆, where dppm = bis(diphenylphosphino)methane, is reported here. The complexes were synthetized and fully characterized by elemental analyses, molar conductivity, UV-Vis, IR, ³¹P{¹H}, ¹H and ¹³C NMR, and the crystal structure of the complex (1) was determined by X-ray diffraction. Complexes (1) and (2) showed high in vitro cytotoxicity against four cancer cells (MDA-MB-231, MCF-7, A549 and DU-145), with IC₅₀ values in the micromolar range (0.03 to 2.70 μM). Importantly, complexes (1) and (2) were more active than the cisplatin, the drug used as a reference in the cytotoxic assays. Moreover, complex (1) showed high selectivity to triple-negative breast cancer cells (MDA-MB-231). Studies of the mechanism of action in MDA-MB-231 cancer cells showed that complex (1) inhibits cell migration, colony formation, and induces cell cycle arrest and apoptosis by activation of the mitochondrial pathway through the loss of mitochondrial membrane potential (ΔΨm). Furthermore, complex (1) induces ROS (Reactive Oxygen Species) generation in MDA-MB-231 cells, which can cause DNA damage. Finally, complexes (1) and (2) interact with DNA by minor grooves and show a moderate interaction with BSA (Bovine Serum Albumin), with the involvement of hydrophobic interactions. Essentially, Ru(II)/diphosphine-naphthoquinone complexes have remarkable cytotoxic effects with high selectivity to triple-negative breast cancer (MDA-MB-231) and could be promising anticancer candidates for cancer treatment. SYNOPSIS: The naphthoquinones Lapachol and Lawsone can form new ruthenium compounds with promising anticancer properties. Show less

This work describes the synthesis of three new ruthenium(ii) complexes with gallic acid and derivatives of the general formula [Ru(L)(dppb)(bipy)]PF₆, where L = gallate (GAC), benzoate (BAC), and esterified-gallate (EGA), bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. The complexes were characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis and IR spectroscopy, and two of them by X-ray crystallography. Cell viability assays show promising results, indicating higher cytotoxicity of the complexes in MDA-MB-231 cells, a triple-negative breast cancer (TNBC) cell line, compared with the hormone-dependent MCF-7 cell line. Studies in vitro with the MDA-MB-231 cell line showed that only Ru(BAC) and Ru(GAC) interacted with BSA. Besides that, the Ru(GAC) complex, which has a polyphenolic acid, interacted in an apo-Tf structure and function dependent manner and it was able to inhibit the formation of reactive oxygen species. Ru(GAC) was able to cause damage to the cellular cytoskeleton leading to inhibition of some cellular processes of TNBC cells, such as invasion, migration, and adhesion. Show less

Ruthenium complexes have been extensively explored as potential molecules for cancer treatment. Considering our previous findings on the remarkable cytotoxic activity exhibited by the ruthenium (II) complex 3-hydroxy-4-methoxybenzoate (hmxbato)-cis-[Ru^II(ŋ²-O₂CC₇H₇O₂)(dppm)₂]PF₆ against Leishmania promastigotes and also the similar metabolic characteristics between trypanosomatids and tumor cells, the present study aimed to analyze the anticancer potential of hmxbato against lung tumor cells, as well as the partial death mechanisms involved. Hmxbato demonstrated selective cytotoxicity against A549 lung tumor cells. In addition, this complex at a concentration of 3.8 µM was able to expressively increase the generation of reactive oxygen species (ROS) in tumor cells, causing an oxidative stress that may culminate in: (1) reduction in cellular proliferation; (2) changes in cell morphology and organization patterns of the actin cytoskeleton; (3) cell arrest in the G2/M phase of the cell cycle; (4) apoptosis; (5) changes in the mitochondrial membrane potential and (6) initial DNA damage. Furthermore, we demonstrated that the induction of programmed cell death can occur by the intrinsic apoptotic pathway through the activation of caspases. It is also worth highlighting that hmxbato exhibited predominant actions on A549 tumor cells in comparison to BEAS-2B normal bronchial epithelium cells, which makes this complex an interesting candidate for the design of new drugs against lung cancer. Show less

The photoactivatable Ru (II) complex 1 [Ru(bipy)2(dpphen)]Cl2 (where bipy = 2,2'-bipyridine and dpphen = 2,9-diphenyl-1,10-phenanthroline) has been shown to possess promising anticancer activity against triple negative adenocarcinoma MDA-MB-231 cells. The present study aims to elucidate the plausible mechanism of action of the photoactivatable complex 1 against MDA-MB-231 cells. Upon photoactivation, complex 1 exhibited time-dependent cytotoxic activity with a phototoxicity index (P Index) of >100 after 72 h. A significant increase in cell rounding and detachment, loss of membrane integrity, ROS accumulation and DNA damage was observed. Flow cytometry and a fluorescent apoptosis/necrosis assay showed an induction of cell apoptosis. Western blot analysis revealed the induction of intrinsic and extrinsic pathways and inhibition of the MAPK and PI3K pathways. The photoproduct of complex 1 showed similar effects on key apoptotic protein expression confirming that it is behind the observed cell death. In conclusion, the present study revealed that complex 1 is a potent multi-mechanistic photoactivatable chemotherapeutic drug that may serve as a potential lead molecule for targeted cancer chemotherapy. Show less

Ruthenium complexes have been recently reported as potential chemotherapeutic agents that offer tumor selectivity and low tumor resistance. This study investigates the photochemistry and the effect of four strained photoactivatable polypyridyl ruthenium(II) complexes on non-small-cell lung cancer (A549) and triple negative breast cancer (MDA-MB-231) cells. All four ruthenium(II) complexes, [Ru(bpy)₂dmbpy]Cl₂ (C1) where (bpy = 2,2'-bipyridine and dmbpy = 6,6'-dimethyl-2,2'-bipyridine), [Ru(phen)₂dmbpy]Cl₂ (C2) where (phen = 1,10-phenanthroline), [Ru(dpphen)₂dmbpy]Cl₂ (C3) (where dpphen = 4,7-diphenyl-1,10-phenanthroline) and [Ru(BPS)₂dmbpy]Na₂ (C4) where (BPS = bathophenanthroline disulfonate) eject the dmbpy ligand upon activation by blue light. Determination of the octanol-water partition coefficient (log P) revealed that C3 was the only lipophilic complex (log P = 0.42). LC-MS/MS studies showed that C3 presented the highest cellular uptake. The cytotoxic effect of the complexes was evaluated with and without blue light activation using WST-1 kit. Data indicated that C3 exhibited the highest cytotoxicity after 72 h (MDA-MB-231, IC₅₀ = 0.73 µM; A549, IC₅₀ = 1.26 µM) of treatment. The phototoxicity indices of C3 were 6.56 and 4.64 for MDA-MB-230 and A549, respectively. Upon light activation, C3 caused significant ROS production and induced apoptosis in MDA-MB-231 cells as shown by flow cytometry. It also significantly increased Bax/Bcl2 ratio and PERK levels without affecting caspase-3 expression. C3 exhibited poor dark toxicity (IC₅₀ = 74 μM) on rat mesenchymal stem cells (MSCs). In conclusion, the physical property of the complexes dictated by the variable ancillary ligands influenced cellular uptake and cytotoxicity. C3 may be considered a promising selective photoactivatable chemotherapeutic agent that induces ROS production and apoptosis. Show less

We report on chemistry and cytotoxic studies of four new ruthenium (II) complexes containing uracil derivatives. All compounds are neutral, presenting the formula [Ru(PPh₃)₂(2TU)₂] (1), [Ru(PPh₃)₂(6m2TU)₂] (2), [Ru(dppb)(2TU)₂] (3) and [Ru(dppb)(6m2TU)₂] (4), where PPh₃ = triphenylphosphine; dppb = 1,4-bis(diphenylphosphino)butane, 2TU = 2-thiouracil and 6m2TU = 6-methyl-2-thiouracil. They were characterized using NMR, UV-vis and IR spectroscopies, microanalytical analysis and mass spectrometry. Furthermore, the crystal structures of 1-4 were determined by single-crystal X-ray diffraction. The coordination of 2-thiouracil derivatives with ruthenium increases regions able to carry out hydrogen bonds with the biological targets, such as DNA. We evaluated the interaction of the complexes with DNA by UV/Vis spectrophotometric titration, and as a result, the values of DNA-binding constants are in the range of 0.8-1.8 × 10⁴ M^-1. Moreover, the interaction of the complexes with BSA was investigated. In vitro, activities against B16-F10 (mouse melanoma), HepG2 (human hepatocellular carcinoma), HL-60 (human promyelocytic leukemia) and K562 (human chronic myelocytic leukemia) and non-tumor cells: PBMC (human peripheral blood mononuclear cells activated with concanavalin A - human lymphoblast) were carried out. Cytotoxicity assays revealed that complexes (2) and (4) present biological activity against tumor cells comparable with oxaliplatin, the reference platinum drug, revealing that they are promising molecules for developing new antitumor compounds. Show less

Herein we discuss five ruthenium(ii) complexes with good cytotoxicity against cancer cells. These complexes are named [Ru(tzdt)(bipy)(dppb)]PF6 (1), [Ru(mmi)(bipy)(dppb)]PF6 (2), [Ru(dmp)(bipy)(dppb)]PF6 (3), [Ru(mpca)(bipy)(dppb)]PF6 (4) and [Ru(2mq)(bipy)(dppb)]PF6 (5), where tzdt = 1,3-thiazolidine-2-thione, mmi = mercapto-1-methyl-imidazole, dmp = 4,6-diamino-2-mercaptopyrimidine, mpca = 6-mercaptopyridine-3-carboxylic acid, 2mq = 2-mercapto-4(3H)-quinazolinone, bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed significant cytotoxic activity for 1-5 against MDA-MB-231, MCF-7, A549, DU-145 and HepG2 tumor cells, higher than that for the standard anticancer drug cisplatin. Compound/DNA interaction studies were carried out showing that 1-5 interact with DNA by electrostatic force of attraction or by hydrogen bonding. Moreover, the complexes interact, moderately and spontaneously, with human serum albumin (HSA) through the hydrophobic region. The five complexes are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (TopIB), and complex 1 is found to be the most efficient TopIB inhibitor among the five compounds. The inhibitory effect and analysis of different steps of the TopIB catalytic cycle indicate that complex 1 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and has no effect on the religation step. Complexes 1, 2 and 3 did not show mutagenic activity when they were evaluated by the cytokinesis-block micronucleus cytome assay in HepG2 cells and the Ames test in the presence and absence of mouse liver S9 metabolic activation. Therefore, it is necessary to perform further in-depth analysis of the therapeutic potential of these promising ruthenium complexes as anticancer drugs. Show less

Ruthenium(II) complexes with 6-methyl-2-thiouracil cis-[Ru(6m2tu)₂(PPh₃)₂] (1) and [Ru(6m2tu)₂(dppb)] (2) (where PPh_3 =triphenylphosphine; dppb = 1,4-bis(diphenylphosphino)butane; and 6m2tu = 6-methyl-2-thiouracil) are potent cytotoxic agents and able to bind DNA. The aim of this study was to evaluate in vitro cellular underlying mechanism and in vivo effectiveness of these ruthenium(II) complexes in human acute promyelocytic leukemia HL-60 cells. Both complexes displayed potent and selective cytotoxicity in myeloid leukemia cell lines, and were detected into HL-60 cells. Reduction of the cell proliferation and augmented phosphatidylserine externalization, caspase-3, -8 and -9 activation and loss of mitochondrial transmembrane potential were observed in HL-60 cells treated with both complexes. Cotreatment with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, reduced Ru(II) complexes-induced apoptosis. In addition, both metal complexes induced phosphorylation of histone H2AX (S139), JNK2 (T183/Y185) and p38α (T180/Y182), and cotreatment with JNK/SAPK and p38 MAPK inhibitors reduced complexes-induced apoptosis, indicating DNA double-strand break and activation of caspase-mediated apoptosis through JNK/p38 pathways. Complex 1 also reduced HL-60 cell growth in xenograft model. Overall, the outcome indicated the ruthenium(II) complexes with 6-methyl-2-thiouracil as a novel promising antileukemic drug candidates. Show less

Combination of multifunctionalities into one compound is a rational strategy in medicinal chemical design, and have often been used with metallodrug-based compounds. In the present study, we synthesized a novel ruthenium-based 5-fluorouracil complex [Ru(5-FU)(PPh₃)₂(bipy)]PF₆ (PPh₃ = triphenylphosphine; and bipy = 2,2'-bipyridine) with enhanced cytotoxicity in different cancer cells, and assessed its apoptosis induction action in human colon carcinoma HCT116 cells. The complex was characterized by infrared, cyclic voltammetry, molar conductance measurements, elemental analysis, NMR experiments and X-ray crystallographic analysis. In both 2D and 3D cell culture models, the complex presented cytotoxicity to cancer cells more potent than 5-FU. A typical morphology of apoptotic cell death, increased internucleosomal DNA fragmentation, without cell membrane permeability, loss of the mitochondrial transmembrane potential, increased phosphatidylserine externalization and caspase-3 activation were observed in complex-treated HCT116 cells. Moreover, the pre-treatment with Z-DEVD-FMK, a caspase-3 inhibitor, reduced the apoptosis induced by the complex, indicating cell death by apoptosis through caspase-dependent and mitochondrial intrinsic pathways. The complex failed to induce reactive oxygen species production and DNA intercalation. In conclusion, the novel complex displays enhanced cytotoxicity to different cancer cells, and is able to induce caspase-mediated apoptosis in HCT116 cells. Show less

Ruthenium-based compounds represent a class of potential antineoplastic drugs. Recently, we designed, synthesized, and identified the Ru(II)-thymine complex [Ru(PPh₃)₂(Thy)(bipy)]PF₆ (where PPh = triphenylphosphine, Thy = thymine and bipy = 2,2'-bipyridine) as a potent cytotoxic agent with the ability to bind to DNA and human and bovine serum albumins. In this study, the underlying cytotoxic mechanism of the [Ru(PPh₃)₂(Thy)(bipy)]PF₆ complex was assessed. This complex displayed potent cytotoxicity in different cancer cell lines; the morphology that is associated with apoptotic cell death, increased internucleosomal DNA fragmentation without cell membrane permeability, loss of the mitochondrial transmembrane potential, increased phosphatidylserine externalization, and caspase-3 activation were observed in human promyelocytic leukemia HL-60 cells that were treated with the complex. Moreover, pretreatment of HL-60 cells with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, partially reduced the apoptosis that was induced by the complex, indicating that the apoptotic cell death occurred through a caspase-mediated pathway. In conclusion, the [Ru(PPh₃)₂(Thy)(bipy)]PF₆ complex displays potent cytotoxicity to different cancer cells and induces caspase-mediated apoptosis in HL-60 cells. Show less

New Ru(II) complexes with lawsone (law) characterized as trans-[Ru(law)(PPh₃)₂(N-N)]PF₆, where PPh₃ means triphenylphosphine and N-N is 2,2'-bipyridine (1), 4,4'-dimethyl-2,2'-bipyridine (2), 4,4'-dimethoxy-2,2'-bipyridine (3), 1,10-phenanthroline (4) or 4,7-diphenyl-1,10-phenanthroline (5), induce apoptosis in tumor cells. Cytotoxicity of the complexes against the tumor cell lines DU-145 (prostate cancer cells), MCF-7 (breast cancer cells), A549 (lung cancer cells) and lung non-tumor cell line MRC-5 demonstrated promising IC₅₀ values, lower than those found for the cisplatin, a drug used as a reference. Due to the high cytotoxic activity and selectivity against A549 cells line, complex (5) was selected for detailed assays. The complex (5) inhibits cells migration in concentrations in a nanomolar range, inducing tumor cell death by apoptosis, as confirmed by flow cytometry experiments. Furthermore, the antiproliferative activity of complex (5) on A549 tumor cells is attributed to a cell cycle arrest at the Sub G1 phase, followed by a decrease in the number of cells at the S phase. In addition, the interaction of the complexes (1-5) with CT-DNA was evaluated by circular dichroism, in which no changes in the secondary structure of DNA were observed, suggesting a weak interaction of the complexes with the biomolecule. On the other hand, complexes (1-5) showed a higher interaction with human serum albumin (HSA) by non-covalent van der Waals forces and hydrogen bonding, resulting in static quenching. Show less

Thirteen new ruthenium amino acid complexes were synthesized and characterized. They were obtained by the reaction of α-amino acids (AA) with [RuCl₂(P-P)(N-N)], where P-P=1,4-bis(diphenylphosphino)butane (dppb) or 1,3-bis(diphenylphosphino)propane (dppp) and N-N=4,4'-dimethyl-2,2'-bipyridine (4'-Mebipy), 5,5'-dimethyl-2,2'-bipyridine (5'-Mebipy) or 4,4'-Methoxy-2-2'-bipyridine (4'-MeObipy). This afforded a family of complexes formulated as [Ru(AA-H)(P-P)(N-N)]PF₆, where AA=glycine (Gly), L-alanine (Ala), L-valine (Val), L-tyrosine (Tyr), L-tryptophan (Trp), L-histidine (His) and L-methionine (Met). All compounds were characterized by elemental analysis, spectroscopic and electrochemical techniques. The [Ru(AA-H)(P-P)(N-N)]PF₆ complexes are octahedral (the AA-H ligand binding involves N-amine and O-carboxylate), diamagnetic (low-spin d⁶, S=0) and present bands due to electronic transitions in the visible region. ¹H, ¹³C{¹H} and ³¹P{¹H} NMR spectra of the complexes indicate the presence of C₂ symmetry, and the identification of diastereoisomers. In vitro cytotoxicity assays of the compounds and cisplatin were carried out using MDA-MB-231 (human breast) tumor cell line and a non-tumor breast cell line (MCF-10A). Most complexes present promising results with IC₅₀ values comparable with the reference drug cisplatin and high selectivity indexes were found for the complexes containing L-Trp. The binding of two Ru-precursors of the type [RuCl₂(dppb)(NN)] (N-N=4'-MeObipy or 4'-Mebipy) to the blood transporter protein human serum albumin (HSA) was evaluated by fluorescence and circular dichroism spectroscopy. Both complexes bind HSA, probably in the hydrophobic pocket near Trp214, and the Ru-complex containing 4'-MeObipy shows higher affinity for HSA than the 4'-Mebipy one. Show less

Synthesis of terpyridyl based ligands 3-([2,2':6',2''-terpyridin]-4'-yl)-7-methoxy-2-(methylthio)-quinolone, (L1); 3-([2,2':6',2''-terpyridin]-4'-yl)-6-methoxyquinolin-2(1H)-one, (L2); 3-([2,2'-:6',2''-terpyridin]-4'-yl)-6-methylquinolin-2(1H)-one (L3) and cyclometalated iridium(iii) complexes [[Ir(ppy)₂L1]⁺PF₆^- (1), [Ir(ppy)₂L2]⁺PF₆^- (2), [Ir(ppy)₂L3]⁺PF₆^- (3) (2-phenylpyridine = Hppy)] involving these ligands has been described. The ligands L1-L3 and complexes 1-3 have been thoroughly characterized by elemental analyses, spectral studies (IR, ¹H, ¹³C NMR, UV/vis and fluorescence) ESI-MS, and the structure of 3 has been unambiguously authenticated by single crystal X-ray analyses. UV/vis, fluorescence and circular dichroism spectroscopic studies showed rather efficient binding of 1 with CT-DNA (calf thymus DNA) and BSA (bovine serum albumin) relative to 2 and 3. Molecular docking studies unveiled binding of 1-3 with minor groove of CT-DNA via van der Waal's forces and electrostatically with the hydrophobic moiety of HSA (human serum albumin). The ligands and complexes exhibited moderate cytotoxicity towards MDA-MB-231 (breast cancer cell line) and significant influence on HeLa (cervical cancer cell line) cells. Cytotoxicity, morphological changes, and apoptosis have been followed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay, Hoechst 33342/PI (PI = propidium iodide) staining, cell cycle analysis by FACS (fluorescence activated cell sorting), and ROS (reactive oxygen species) generation by DCFH-DA (dichlorodihydrofluorescein diacetate) dye. Confocal microscopy images revealed that the drug efficiently initiates apoptosis in the cell cytosol. The IC₅₀ values showed superior cytotoxicity of 1-3 against the HeLa cell line relative to cisplatin, and their ability to induce apoptosis is in the order 1 > 2 > 3. Show less

Three new mixed and mononuclear Ru(II) complexes containing 1,3-thiazolidine-2-thione (tzdtH) were synthesized and characterized by spectroscopic analysis, molar conductivity, cyclic voltammetry, high-resolution electrospray ionization mass spectra and X-ray diffraction. The complexes presented unique stereochemistry and the proposed formulae are: [Ru(tzdt)(bipy)(dppb)]PF6 (1), cis-[Ru(tzdt)2(PPh3)2] (2) and trans-[Ru(tzdt)(PPh3)2(bipy)]PF6 (3), where dppb=1,4-bis(diphenylphosphino)butane and bipy=2,2'-bipyridine. These complexes demonstrated strong cytotoxicity against cancer cell lines when compared to cisplatin. Specifically, complex 2 was the most potent cytotoxic agent against MCF-7 breast cells, while complexes 1 and 3 were more active in DU-145 prostate cells. Binding of complexes to ctDNA was determined by UV-vis titration and viscosity measurements and revealed binding constant (Kb) values in range of 1.0-4.9×10(3)M(-1), which are characteristic of compounds possessing weak affinity to ctDNA. In addition, these complexes presented antiparasitic activity against Trypanosoma cruzi. Specifically, complex 3 demonstrated strong potency, moderate selectivity index and acted in synergism with the approved antiparasitic drug, benznidazole. Additionally, complex 3 caused parasite cell death through a necrotic process. In conclusion, we demonstrated that Ru(II) complexes have powerful pharmacological activity, while the metal-free tzdtH does not provoke the same outcome. Show less

Four organometallic complexes [(η(6)-C6H6)RuCl(pmpzdpm)], 1; [(η(6)-C6H6)RuCl(pypzdpm)], 2; [(η(6)-C10H14)RuCl(pmpzdpm)], 3 and [(η(6)-C10H14)RuCl(pypzdpm)], 4 containing 5-(2-pyrimidyl-piperazine)phenyldipyrromethene (pmpzdpm) and 5-(2-pyridylpiperazine)phenyldipyrromethene (pypzdpm) have been designed and synthesized. The complexes 1-4 have been fully characterized by elemental analyses and spectroscopic studies (ESI-MS, IR, (1)H, (13)C NMR, UV-vis). Their electrostatic/intercalative interaction with CT DNA has been investigated by UV-vis and competitive ethidium bromide displacement studies while their protein binding affinity toward bovine serum albumin (BSA) was realized by UV-vis, fluorescence, synchronous and three dimensional (3D) fluorescence studies. The interaction with DNA and protein has further been validated by in silico studies. Cellular uptake, in vitro cytotoxicity and flow cytometric analyses have been performed to determine the mode of cell death against the kidney cancer cell line ACHN. Cell cycle analysis suggested that the complexes cause cell cycle arrest in the subG1 phase and overall results indicated that the in vitro antitumor activity of 1-4 lies in the order of 3 >4 >1 >2 (IC50, 7.0 1; 8.0 2; 2.0 3; 4.0 μM,4 ). Show less

Herein we synthesized two new ruthenium(II) compounds [Ru(pySH)(bipy)(dppb)]PF6 (1) and [Ru(HSpym)(bipy)(dppb)]PF6 (2) that are analogs to an antitumor agent recently described, [Ru(SpymMe2)(bipy)(dppb)]PF6 (3), where [(Spy) = 2-mercaptopyridine anion; (Spym) = 2-mercaptopyrimidine anion and (SpymMe2) = 4,6-dimethyl-2-mercaptopyrimidine anion]. In vitro cell culture experiments revealed significant anti-proliferative activity for 1-3 against HepG2 and MDA-MB-231 tumor cells, higher than the standard anti-cancer drugs doxorubicin and cisplatin. No mutagenicity is detected when compounds are evaluated by cytokinesis-blocked micronucleus cytome and Ames test in the presence and absence of S9 metabolic activation from rat liver. Interaction studies show that compounds 1-3 can bind to DNA through electrostatic interactions and to albumin through hydrophobic interactions. The three compounds are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (Top1). Compound 3 is the most efficient Top1 inhibitor and the inhibitory effect is enhanced upon pre-incubation with the enzyme. Analysis of different steps of Top1 catalytic cycle indicates that 3 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and slows down the religation reaction. Molecular docking shows that 3 preferentially binds closer to the residues of the active site when Top1 is free and lies on the DNA groove downstream of the cleavage site in the Top1-DNA complex. Thus, 3 can be considered in further studies for a possible use as an anticancer agent. Show less

Four ruthenium(II)-based complexes with N-(acyl)-N',N'-(disubstituted)thiourea derivatives (Th) were obtained. The compounds, with the general formula trans-[Ru(PPh3)2(Th)(bipy)]PF6, interact with bovine serum albumin (BSA) and DNA. BSA-binding constants, which were in the range of 3.3-6.5×10(4) M(-1), and the thermodynamic parameters (ΔG, ΔH and ΔS), suggest spontaneous interactions with this protein by electrostatic forces due to the positive charge of the complexes. Also, binding constant by spectrophotometric DNA titration (Kb = 0.8-1.8×10(4) M(-1)) and viscosity studies indicate weak interactions between the complexes and DNA. Cytotoxicity assays against DU-145 (prostate cancer) and A549 (lung cancer) tumour cells revealed that the complexes are more active in tumour cells than in normal (L929) cells, and that they present high cytotoxicity (low IC50 values) compared with the reference metallodrug, cisplatin. Show less