In vitro anti-tumour and cyto-selective effects of coumarin-3-carboxylic acid and three of its hydroxylated derivatives, along with their silver-based complexes, using human epithelial carcinoma cell lines

Silver, Its Salts and Application in Medicine and Pharmacy

The healing properties of silver have been used since ancient times. The main aim of the study was to collect and review the literature on the clinical potential of silver, its salts and complex compounds. The second goal was to present an outline of the historical use of silver in medicine and pharmacy, taking into account the possibility of producing pharmaceutical drug forms on the premises of pharmacies. In the context of the growing resistance of microorganisms to available, widely used antibiotics, silver plays a key role. There is only one known case of bacterial resistance to silver-the Pseudomonas stutzeri strain, which naturally occurs in silver mines. The development of research in the field of coordination chemistry offers great opportunities in the design of new substances in which silver ions can be incorporated. These substances exhibit increased potency and often an extended antimicrobial spectrum. Silver-based compounds are, however, only limited to external applications, as opposed to their historic oral administration. Advanced studies of their physicochemical, microbiological, cytotoxic and genotoxic properties are ongoing and full of challenges. The improvement of the methods of synthesis gives the possibility of applying the newly synthesized compounds ex tempore, as was the case with the complex of metronidazole with silver (I) nitrate. Some of these experimental efforts performed in vitro are followed with clinical trials. The third and final goal of this study was to present the possibility of obtaining an ointment under the conditions of an actual pharmacy using silver (I) salts and a ligand, both of which are active substances with antimicrobial properties.

Synthesis, DNA binding and biological evaluation of benzimidazole Schiff base ligands and their metal(ii) complexes

Two novel benzimidazole ligands (E)-2-((4-(1H-benzo[d]imidazole-2-yl)phenylimino)methyl)-6-bromo-4-chlorophenol (L1) and (E)-1-((4-(1H-benzo[d]imidazole-2-yl)phenylimino)methyl)naphthalene-2-ol (L2) with their corresponding Cu(ii), Ni(ii), Pd(ii) and Zn(ii) complexes were designed and synthesized. The compounds were characterized by elemental, IR, and NMR (1H & 13C) spectral analyses. Molecular masses were determined by ESI-mass spectrometry, and the structure of ligand L1 was confirmed by single crystal X-ray diffraction analysis. Molecular docking was carried out for the theoretical investigation of DNA binding interactions. The results obtained were verified experimentally by UV/Visible absorption spectroscopy in conjunction with DNA thermal denaturation studies. It was observed that ligands (L1 and L2) and complexes (1-8) were moderate to strong DNA binders, as evident from the binding constants (K b). The value was found to be highest for complex 2 (3.27 × 105 M-1) and lowest for 5 (6.40 × 103 M-1). A cell line study revealed that breast cancer cells were less viable to the synthesized compounds compared to that of standard drugs, cisplatin and doxorubicin, at the same concentration. The compounds were also screened for in vitro antibacterial activity for which complex 2 showed a promising broad-spectrum effect against all tested strains of bacteria, almost in the proximity of the reference drug kanamycin, while the rest of the compounds displayed activity against selected strains.

Umbelliferone attenuates diabetic cardiomyopathy by suppression of JAK/STAT signaling pathway through amelioration of oxidative stress and inflammation in rats

Umbelliferone (UMB), 7-hydroxycoumarin, is a naturally occurring coumarin derivative that has a plethora of biological and therapeutic activities. The focus of this research was to elucidate the curative effects of two different doses of UMB on diabetic cardiomyopathy (DCM) in a type 2 diabetic rat model induced by 50 mg/kg body weight of streptozotocin (STZ). Diabetic rats orally received 10 or 30 mg/kg of UMB daily for 8 weeks. Compared to the nontreated diabetic group, both UMB treatment doses significantly decreased glucose levels, glycated hemoglobin (HbA1c), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), creatine kinase MB (CK-MB), cardiovascular risk indices, and oxidative stress by reducing malondialdehyde (MDA) and increasing the activity of the antioxidant enzymes. The hypercholesterolemia and hypertriglyceridemia also dramatically decreased in diabetic groups with UMB treatments accompanied by an improvement in insulin, and insulin sensitivity indices (HOMA-IR and QUICKI). Furthermore, the cardiac gene expressions and protein levels of Janus kinase2 (JAK2), signal transducer and activator of transcription3 (STAT3), and transforming growth factor beta1 (TGF-β1) were also markedly downregulated in a dose-dependent manner by UMB treatments. Finally, the biochemical results were assured by the reduction of histological alterations in cardiac tissues. In conclusion, UMB is a propitious substance for the treatment of DCM by virtuousness of its antihyperglycemic, antihyperlipidemic, antioxidant, and anti-inflammatory properties through modulating the JAK/STAT signaling pathway that may be the underlying mechanism in UMB action.

Triphenyltin(IV) dithiocarbamate compound induces genotoxicity and cytotoxicity in K562 human erythroleukemia cells primarily via mitochondria-mediated apoptosis

The novel di-and triphenyltin(IV) dithiocarbamate compounds represented as R_nSnL₂ (where R = C₄H₉, C₆H₅; n = 2,3; L = N,N-dithiocarbamate), Ph₂Sn(N,N-diisopropyldithiocarbamate) (OC1), Ph₃Sn(N,N-diisopropyldithiocarbamate) (OC2), Ph₂Sn(N,N-diallyldithiocarbamate) (OC3), Ph₃Sn(N,N-diallyldithiocarbamate) (OC4), and Ph₂Sn(N,N-diethyldithiocarbamate) (OC5) were assessed for their cytotoxicity in K562 human erythroleukemia cells. All compounds inhibited the growth of cells at low micromolar concentrations (<10 μM), and the mechanism underlying their antiproliferative effects on K562 cells was apoptosis, as corroborated by the exposure of plasma membrane phosphatidylserine. OC2, which showed the most promising antiproliferative activity, was selected for further analyses. The results demonstrated that OC2 induced apoptosis in K562 cells via an intrinsic mitochondrial pathway triggered upon DNA damage, an early apoptotic signal. Subsequently, OC2 produced excessive intracellular reactive oxygen species. The role of oxidative stress was corroborated by the significant reduction in GSH levels and percentage of apoptosis in NAC-pretreated cells. OC2 could arrest the cell cycle progression in the S phase. These new findings elucidate the antiproliferative potential of OC2 in the K562 human erythroleukemia cells and warrant further investigation, specifically to determine the exact signaling pathway underlying its antileukemic efficacy.

Molecular docking and in vitro anticancer studies of silver(I)-N-heterocyclic carbene complexes

A series of symmetric and unsymmetrical benzimidazolium-based N-heterocyclic carbene (NHC) precursors (1a-i) and their silver complexes (2a-i) have been synthesized. The Ag(I)–NHC complexes were characterized by ¹H, ¹³C{¹H} NMR, FTIR, LC/MS-QTOF, and elemental analysis. Anticancer and cytotoxic activity of all Ag(I)–NHC complexes were tested against healthy fibroblast cell line (L929), breast cancer cell line (MCF-7), and neuroblastoma cell line (SH-SY5Y) by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4sulfophenyl)-2H-tetrazolium] assay. The 2b, 2c, 2e, 2g, 2h, and 2i complexes showed higher cytotoxicity than cisplatin against SH-SY5Y and MCF-7 and lower cytotoxic activity against L929 cell lines. Because of their high cytotoxic activity against cancer cells and low cytotoxicity against healthy fibroblast cell lines, the 2b, 2c, 2e, 2g, 2h, and 2i are expected to be new lead compounds. In addition, molecular docking studies were performed to explore the binding interactions of silver complexes with the enzyme to explore new anticancer compounds. Furthermore, ADME properties of all complexes were predicted to explore lead-like characteristics and may be a potential drug candidate for cancer treatment.

Pegylated-polycaprolactone nano-sized drug delivery platforms loaded with biocompatible silver(i) complexes for anticancer therapeutics

Cytotoxic potential of Ag(i) coordination compounds against cancer cells is widely recognized, but their frequently low water solubility and potential adverse interactions of Ag(i) ions in biological media require their incorporation into suitable platforms to ensure effective transport and delivery at target sites. Herein, we developed and evaluated the in vitro cytotoxic activity of a biodegradable copolymer-based nano-sized drug delivery system for three cytotoxically active and lipophillic Ag(i) compounds. In particular, polymer-based nanoparticles of the newly synthesized amphiphilic methoxy-poly(ethylene glycol)-poly(caprolactone) (mPEG-PCL) copolymer were prepared as carriers for [Ag(dmp2SH)(PPh3)2]NO3 (1), [Ag(dmp2SH)(xantphos)]NO3 (2) and [Ag(dmp2S)(xantphos)] (3) (dmP2SH = 4,6-dimethylpyrimidine-2-thiol, xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) which exhibit high cytotoxicity against HeLa cancer cells, while they maintain low toxicity against HDFa normal cells. Taking advantage of the favorable donor-acceptor Lewis acid-base and electrostatic interactions between functional groups of 1-3 and mPEG-PCL copolymer, the formation of [X]@mPEG-PCL (X = 1,2,3) nanoparticles with nearly spherical shape was achieved. Satisfactory loading capacities and encapsulation efficiencies were obtained (13-15% and 80-88%, respectively). Differences in their mean size diameters were observed, revealing a dependence on the individual structural characteristics of the Ag(i) compounds. In vitro release profiles of the nanoparticles showed an initial burst stage, followed by a prolonged release stage extending over 15 days, with their release rates being determined by the mean size of the nanoparticles, as well as the type and crystallinity of the encapsulated Ag(i) compounds. In vitro cytotoxicity studies revealed an increased cytotoxic activity of compounds 1-3 after their encapsulation in mPEG-PCL copolymer against HeLa cells, with the actual concentrations of the loaded compounds responsible for the inhibition of cell viability being reduced by 8 times compared to the compounds in free form. Therefore, the current drug delivery system improves the pharmacokinetic properties of the three cytotoxic and biocompatible Ag(i) compounds, and may be beneficial for future in vivo anticancer treatment.

Coumarins and Gastrointestinal Cancer: A New Therapeutic Option?

Cancers of the gastrointestinal (GI) tract are often life-threatening malignancies, which can be a severe burden to the health care system. Globally, the mortality rate from gastrointestinal tumors has been increasing due to the lack of adequate diagnostic, prognostic, and therapeutic measures to combat these tumors. Coumarin is a natural product with remarkable antitumor activity, and it is widely found in various natural plant sources. Researchers have explored coumarin and its related derivatives to investigate their antitumor activity, and the potential molecular mechanisms involved. These mechanisms include hormone antagonists, alkylating agents, inhibitors of angiogenesis, inhibitors of topoisomerase, inducers of apoptosis, agents with antimitotic activity, telomerase inhibitors, inhibitors of human carbonic anhydrase, as well as other potential mechanisms. Consequently, drug design and discovery scientists and medicinal chemists have collaborated to identify new coumarin-related agents in order to produce more effective antitumor drugs against GI cancers. Herein, we summarize the therapeutic effects of coumarin and its derivatives against GI cancer.

Synthesis, Spectroscopy, Single-Crystal Structure Analysis and Antibacterial Activity of Two Novel Complexes of Silver(I) with Miconazole Drug

In a previous article, we reported on the higher toxicity of silver(I) complexes of miconazole [Ag(MCZ)₂NO₃ (1)] and [Ag(MCZ)₂ClO₄ (2)] in HepG2 tumor cells compared to the corresponding salts of silver, miconazole and cisplatin. Here, we present the synthesis of two silver(I) complexes of miconazole containing two new counter ions in the form of Ag(MCZ)₂X (MCZ = 1-[2-(2,4-dichlorobenzyloxy)-2-(2,4-dichlorophenyl)ethyl]-1H-imidazole]; X = BF₄⁻ (3), SbF₆⁻ (4)). The novel silver(I) complexes were characterized by elemental analysis, ¹H NMR, ¹³C NMR and infrared (IR) spectroscopy, electrospray ionization (ESI)-MS spectrometry and X-ray-crystallography. In the present study, the antimicrobial activity of all obtained silver(I) complexes of miconazole against six strains of Gram-positive bacteria, five strains of Gram-negative bacteria and yeasts was evaluated. The results were compared with those of a silver sulfadiazine drug, the corresponding silver salts and the free ligand. Silver(I) complexes exhibited significant activity against Gram-positive bacteria, which was much better than that of silver sulfadiazine and silver salts. The highest antimicrobial activity was observed for the complex containing the nitrate counter ion. All Ag(I) complexes of miconazole resulted in much better inhibition of yeast growth than silver sulfadiazine, silver salts and miconazole. Moreover, the synthesized silver(I) complexes showed good or moderate activity against Gram-negative bacteria compared to the free ligand.

Energy transfer mechanism in luminescence Eu(III) and Tb(III) complexes of coumarin-3-carboxylic acid: A theoretical study

Excited state energy level diagrams of coumarin-3-carboxylic acid (HCCA) chromophore, Eu(CCA)Cl₂(H₂O)₂ (1), Eu(CCA)₂Cl(H₂O)₂ (2)_, Eu(CCA)₃(H₂O)₃ (3), Tb(CCA)₂Cl(H₂O) (4) and Tb(CCA)₂(NO₃)(H₂O) (5) in gas phase and polar solution have been calculated by means of DFT/TDDFT/ωB97XD methods. Based on these results, the ability of CCA to sensitize Eu(III) and Tb(III) luminescence has been examined. The competitive excited state processes in the complexes - fluorescence, intersystem crossing (ISC) and phosphorescence, were analyzed depending on the environment, number of the ligands, Ln(III) ion type (Eu and Tb) and counteranion (Cl^- and NO₃^-). It has been found that the environment altered the S₁ state energy, oscillator strength, fluorescence lifetime as well as the S₁ character - polar solution stabilized the S₁(ππ*) state, whereas non-polar solution (gas phase, solid state) stabilized the S₁(nπ*) state. The S₁(nπ*) state was decisive for the efficient energy transfer as it suppressed the S₁ emission of CCA and favored ISC or direct transfer to the emitting levels of Eu(III). The HCCA triplet (T₁) state minimum energy (~2.7, ~2.6^ZPE eV) and (ππ*) character were retained in Eu/Tb-CCA complexes regardless of the environment. The energy gap between the higher energy T₁ donor state and the acceptor levels ⁵D₁ of Eu(III) (~0.5 eV) and ⁵D₄ of Tb(III) (~0.1 eV) provided optimal resonance conditions for effective energy transfer for Eu(III), but less probability for Tb(III). The nonradiative energy (CCA → Eu(III)) transfer rates and quantum luminescence yield for 2 and 3 were calculated by a strategy combining DFT geometries, INDO/S excitation energies and calculated Judd-Ofelt parameters. The excitation channel T₁ → ⁵D₀ through an exchange mechanism was predicted as the most probable one to populate the main emissive Eu-centered state in complexes 2 and 3. The more efficient luminescence of 3 than that of 2 was discussed and explained.

Design, synthesis and in vivo evaluation of 3-arylcoumarin derivatives of rhenium(I) tricarbonyl complexes as potent antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA)

We have prepared a series of ten 3-arylcoumarin molecules, their respective fac-[Re(CO)₃(bpy)L]⁺ and fac-[Re(CO)₃(L⁀L)Br] complexes and tested all compounds for their antimicrobial efficacy. Whereas the 3-arylcoumarin ligands are virtually inactive against the human-associated pathogens with minimum inhibitory concentrations (MICs) > 150 μM, when coordinated to the fac-[Re(CO)₃]⁺ core, most of the resulting complexes showed remarkable antibacterial potency. Several rhenium complexes exhibit activity in nanomolar concentrations against Gram-positive pathogens such as Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA) and Enterococcus faecium. The molecules do not affect bacterial cell membrane potential, but some of the most potent complexes strongly interact with DNA, indicating it as a possible target for their mode of action. In vivo studies in the zebrafish model showed that the complexes with anti-staphylococcal/MRSA activity were non-toxic to the organism even at much higher doses of the corresponding MICs. In the zebrafish-MRSA infection model, the complexes increased the survival rate of infected fish up to 100% and markedly reduced bacterial burden. Moreover, all rescued fish developed normally following the treatments with the metallic compounds.

In vitro biological evaluation and consideration about structure-activity relationship of silver(I) aminoacidate complexes

Two silver(I) aminoacidate complexes {[Ag₄(L-HAla)₄(NO₃)₃]NO₃}_n (AgAla, complex 1, Ala = alanine) and {[Ag(L-Phe)]}_n (AgPhe, complex 2, Phe = phenylalanine) were prepared and characterized by elemental, spectral analysis (FT-IR, NMR techniques) and single crystal X-ray analysis in solid state and their solution stability was measured in biological testing time-scale by ¹H NMR. The bridging coordination modes of the zwitterionic Ala and deprotonated Phe ligands led to the formation of 1D polymeric chains of the complexes. The significant argentophilic interactions are presented in the structure of AgAla. Antimicrobial testing of prepared Ag(I) complexes was evaluated by IC₅₀ and MIC values and were compared with AgGly, silver(I) sulfadiazine and AgNO₃ samples. Moreover, MTS test was used to the testing of broad range antiproliferative activity of studied compounds against different cancer cell lines and also to the investigation of calf thymus DNA interactions by absorption spectroscopy, fluorescence spectroscopy, Ethidium bromide/Hoechst 33258 displacement experiments and circular dichroism spectroscopy. To evaluate the pUC19 DNA fragmentation by silver(I) complexes, the agarose gel electrophoresis was used. In addition to biological evaluation we used lipophilicity measurement results in the discussion about structure-activity relationship (SAR).

(Amino)cyclophosphazenes as Multisite Ligands for the Synthesis of Antitumoral and Antibacterial Silver(I) Complexes

The reactivity of the multisite (amino)cyclotriphosphazene ligands, [N₃P₃(NHCy)₆] and [N₃P₃(NHCy)₃(NMe₂)₃], has been explored in order to obtain silver(I) metallophosphazene complexes. Two series of cationic silver(I) metallophosphazenes were obtained and characterized: [N₃P₃(NHCy)₆{AgL}_n](TfO)_n [n = 2, L = PPh₃ (2), PPh₂Me (4); n = 3, L = PPh₃ (3), PPh₂Me (5), TPA (TPA = 1,3,5-triaza-7-phosphaadamantane, 6)] and nongem-trans-[N₃P₃(NHCy)₃(NMe₂)₃{AgL}_n](TfO)_n [n = 2, L = PPh₃ (7), PPh₂Me (9); n = 3, L = PPh₃ (8), PPh₂Me (10)]. 5, 7, and 9 have also been characterized by single-crystal X-ray diffraction, thereby allowing key bonding information to be obtained. Compounds 2-6, 9, and 10 were screened for in vitro cytotoxic activity against two tumor human cell lines, MCF7 (breast adenocarcinoma) and HepG2 (hepatocellular carcinoma), and for antimicrobial activity against five bacterial species including Gram-positive, Gram-negative, and Mycobacteria strains. Both the IC₅₀ and MIC values revealed excellent biological activity for these metal complexes, compared with their precursors and cisplatin and also AgNO₃ and silver sulfadiazine, respectively. Both IC₅₀ and MIC values are among the lowest values found for any silver derivatives against the cell lines and bacterial strains used in this work. The structure-activity relationships were clear. The most cytotoxic and antimicrobial derivatives were those with the triphenylphosphane and [N₃P₃(NHCy)₆] ligands. A significant improvement in the activity was also observed upon a rise in the number of silver atoms linked to the phosphazene ring.

Light-stable polypyridine silver(i) complexes of 1,3,5-triaza-7-phosphaadamantane (PTA) and 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S): significant antiproliferative activity of representative examples in aqueous media

A series of novel silver(i) 2,2':6',2''-terpyridine (tpy), 4'-(4-methylphenyl)-2,2':6':2''-terpyridine (tpy-Ph-Me) and 1,10-phenanthroline-5,6-dione (dione) derivatives containing PTA (1,3,5-triaza-7-phosphaadamantane) or 1,3,5-triaza-7-phosphaadamantane-7-sulfide (PTA[double bond, length as m-dash]S) have been synthesized and fully characterized. Two types of complexes have been obtained, monocationic [Ag(tpy)(PTA)](NO₃) (1), [Ag(tpy-Ph-Me)(PTA)](NO₃) (2), [Ag(dione)(PTA[double bond, length as m-dash]S)](BF₄) (4) and [Ag(dione)₂](PF₆) (5) and neutral [Ag(dione)(PTA[double bond, length as m-dash]S)(NO₃)] (3). The solid-state structures of four complexes have been determined by single-crystal X-ray diffraction. Complexes 1 and 2 are luminescent at room temperature and 77 K while 5 shows emission only at 77 K. Compounds 3 and 4 are not emissive. Furthermore, representative light-stable and water-soluble 1 and 3 were evaluated for their cytotoxic activities on the normal human dermal fibroblast (NHDF) cell line and their antitumor activity using the human lung carcinoma (A549), epithelioid cervix carcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cell lines. Interactions between the complexes and human serum albumin (HSA) using UV-Vis, fluorescence and circular dichroism spectroscopy (CD) were also investigated.

Blue-emitting acridine-tagged silver(i)-bis-N-heterocyclic carbene

Herein, the photophysical properties of an acridine derivative of a bis-N-heterocyclic carbene silver complex were investigated. The HOMO and LUMO energy differences between 9-[(N-methyl imidazol-2-ylidene)]acridine and 4,5-bis[(N-methyl-imidazol-2-ylidene)methyl]acridine were theoretically compared. Based on the calculation, the 4,5-bis N-heterocyclic carbene-tethered acridine type of ligand was found to be a potential source for tuning the fluorescent nature of the resultant metal derivatives. Thus, a 4,5-bis N-heterocyclic carbene (NHC)-tethered acridine silver(i) salt was synthesized, and its photophysical properties were investigated. The 4,5-bis[(N-isopropylimidazol-2-ylidene)methyl]acridine silver(i) hexafluorophosphate complex was obtained from the reaction between [4,5-bis{(N-isopropylimidazolium)methyl}acridine] hexafluorophosphate and Ag₂O in very good yield; this molecule was characterized by elemental analysis and FTIR, multinuclear (¹H and ¹³C) NMR, UV-Vis, and fluorescence spectroscopic techniques. The molecular structure has been confirmed by single-crystal X-ray diffraction analysis, which has revealed that the complex is a homoleptic mononuclear silver(i) cationic solid. The charge of the Ag(i)–NHC cation is balanced by the hexafluorophosphate anion. The cationic moieties are closely packed in the chair and inverted chair forms where silver(i) possesses a quasi-linear geometry. Moreover, the silver complex provided blue emission from all the three excitations with good fluorescence quantum yield. The fluorescence lifetime of the silver(i) complex has been determined using the time-correlated single photon counting technique. Interestingly, the fluorescence decay pattern and the fluorescence lifetimes of the silver complex are largely different from those of the parent ligand acridine imidazolium salt. Moreover, the theoretical predictions have been found to be in good agreement with the experimental results.

The synthesis and photophysical properties of blue-emitting acridine-tagged silver(i)-bis-N-heterocyclic carbene are reported.

The effects of bromine atoms on the photophysical and photochemical properties of 3-cinnamoylcoumarin derivatives

Coumarin derivatives modified using bromine atoms linked onto the right benzene ring (mainly in the HOMO) could enhance singlet oxygen generation capability.

Novel Gold and Silver Carbene Complexes Exert Antitumor Effects Triggering the Reactive Oxygen Species Dependent Intrinsic Apoptotic Pathway

Cisplatin and other platinum-based drugs are well-known valid anticancer drugs. However, during chemotherapy, the presence of numerous side effects and the onset of frequent phenomena of resistance has pushed many research groups to devise new metal-based compounds holding improved anticancer properties and fewer undesired effects. Amongst the variety of synthesized compounds, significant antiproliferative effects have been obtained by employing organometallic compounds, particularly those based on silver and gold. With this in mind, we synthesized four compounds, two silver complexes and two gold complexes, with good inhibitory effects on the in vitro proliferation of breast and ovarian cancer-cell models. The antitumor activity of the most active compound, that is, AuL4, was found to be ninefold higher than that of cisplatin, and this compound induced dramatic morphological changes in HeLa cells. AuL4 induced PARP-1 cleavage, caspases 3/7 and 9 activation, mitochondria disruption, cytochrome c release in cancer-cell cytoplasm, and the intracellular production of reactive oxygen species. Thus, AuL4 treatment caused cancer-cell death by the intrinsic apoptotic pathway, whereas no cytotoxic effects were recorded upon treating non-tumor cell lines. The reported outcomes may be an important contribution to the expanding knowledge of medicinal bio-organometallic chemistry and enlarge the available anticancer toolbox, offering improved features, such as higher activity and/or selectivity, and opening the way to new discoveries and applications.

New bimetallic dicyanidoargentate(I)-based coordination compounds: Synthesis, characterization, biological activities and DNA-BSA binding affinities

Four compounds -two (2 and 3) completely new- of composition [Ni(edbea)Ag₃(CN)₅] (1), [Cu(edbea)Ag₂(CN)₄]·H₂O (2), [Cd(edbea)Ag₃(CN)₅]·H₂O (3) and [Cd(edbea)₂] [Ag(CN)₂]₂·H₂O (4) {edbea; 2,2'-(ethylenedioxy)bis (ethylamine)}, were synthesized and characterized using elemental, FT-IR, X-Ray (4), thermal, variable temperature magnetic measurement (1 and 2) and biological techniques. The DNA/BSA binding affinities of 2 and 3 were evaluated by UV-Vis spectrophotometric titrations, ethidium bromide exchange experiments and electrophoretic mobility measurements. Compounds 1 and 4 have previously been characterized and shown to reduce the proliferation and migration of tumor cells. For the sake of clarity, 1 precise mechanism of action on microbial organisms and temperature magnetic measurement were determined. The crystallographic analyses showed that 4 was built up of [Cd(edbea)₂]^II cations and [Ag₂(CN)₄]^II anions. Complexes demonstrated a remarkable antibacterial (1-4), antifungal (1-4) and antiproliferative activities (2 and 3) to ten human bacterial pathogens, four plant pathogenic fungi or three tumor cells (HeLa, HT29, and C6), respectively. Therefore, our results strongly confirm that cell proliferation, cell morphology, Bcl-2, P53 changes and apoptosis can be related to the pharmacological effects of the complexes as suitable candidate for clinical trials.

Synthesis of Ag(I) camphor sulphonylimine complexes and assessment of their cytotoxic properties against cisplatin-resistant A2780cisR and A2780 cell lines

Camphorsulphonylimine complexes [Ag(NO₃)(^IL)₂] (^IL=C₁₂H₁₉N₃SO₂, 1) and [(AgNO₃)₂(^IIL)] (^IIL=C₂₂H₂₃N₃SO₂, 2) were synthesized and characterized by elemental analysis, spectroscopy (IR, NMR) and cyclic voltammetry. [Ag(NO₃)(^IL)₂] crystalizes in the monoclinic C2 space group with a triangular geometry assuming a chalice-type shape. The anti-proliferative properties of the new complexes 1 and 2 and those of the previously reported [Ag(NO₃)(^IIIL)] (^IIIL=C₁₆H₁₈N₃SO₂, 3) were assessed against the human ovarian cancer cells (cisplatin-sensitive A2780, cisplatin-resistant A2780cisR) and the non-tumoral human HEK 293 cell line, using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The NR (3-amino-7-dimethylamino-2-methylphenazine hydrochloride) assay was alternatively used to assess the cytotoxicity on the A2780 cells. Results from the MTT assay (48h exposure) show that the complexes display IC₅₀ values lower (by at least one order of magnitude) than cisplatin, while the cytotoxicity of AgNO₃ is of the same order of cisplatin. The camphorsulphonylimine ligands display irrelevant (^IL, ^IIIL) or no cytotoxicity (^IIL). The highest cytotoxicity (lower IC₅₀) was found for [(AgNO₃)₂(^IIL)]. The binding ability of the complexes to calf thymus-deoxyribonucleic acid (CT-DNA) was studied by fluorescence. Constants (K_sv, K_a) and the number (n) of binding centres to DNA were calculated showing that DNA intercalation possibly occurs in the cases of complexes 2 and 3, while a more complicated process operates for 1. As expected from the cytotoxicity, [(AgNO₃)₂(^IIL)] displays the highest binding affinity (K_a=1.61×105 M^-1). No binding to DNA was detected for AgNO₃ or ^IIL under the experimental conditions used. The binding trend to CT-DNA found by fluorescence was corroborated by cyclic voltammetry.

Self-Assembly of the Second Transmembrane Domain of hCtr1 in Micelles and Interaction with Silver Ion

Human copper transporter 1 (hCtr1) transports copper and silver by a homotrimer. The protein contains three transmembrane domains in which the second transmembrane domain (TMD2) is a key component lining the central pore of the trimer. The MXXXM motif in the C-terminal end of TMD2 plays a significant role in the function of hCtr1. In this study, we characterized the structure and assembly of isolated TMD2 of hCtr1 in sodium dodecyl sulfate (SDS) micelles and the interaction of the micelle-bound peptide with silver ion using nuclear magnetic resonance, circular dichroism, isothermal titration calorimetry and electrophoresis techniques. We detected the formation of a trimer of the isolated hCtr1-TMD2 in SDS micelles and the binding of the trimer to Ag(I) by a chemical stoichiometry of 3:2 of peptide:Ag(I). We showed that either an intensive pretreatment of the TMD2 peptide by 1,1,1,3,3,3-hexafluoro-2-propanol solvent or a conversion from methionine to leucine in the MXXXM motif changes the aggregation structure of the peptide and decreases the binding affinity by 1 order of magnitude. Our results suggest that the intrinsic interaction of the second transmembrane domain itself may be closely associated with the formation of hCtr1 pore in cellular membranes, and two methionine residues in the MXXXM motif may be important for TMD2 both in the trimeric assembly and in a higher-affinity binding to Ag(I).

Macrophage and colon tumor cells as targets for a binuclear silver(I) N-heterocyclic carbene complex, an anti-inflammatory and apoptosis mediator

Chronic inflammation intensifies the risk for malignant neoplasm, indicating that curbing inflammation could be a valid strategy to prevent or cure cancer. Cancer and inflammation are inter-related diseases and many anti-inflammatory agents are also used in chemotherapy. Earlier, we have reported a series of novel ligands and respective binuclear Ag(I)-NHC complexes (NHC=N-heterocyclic carbene) with potential anticancer activity. In the present study, a newly synthesized salt (II) and respective Ag(I)-NHC complex (III) of comparable molecular framework were prepared for a further detailed study. Preliminarily, II and III were screened against HCT-116 and PC-3 cells, wherein III showed better results than II. Both the compounds showed negligible toxicity against normal CCD-18Co cells. In FAM-FLICA caspase assay, III remarkably induced caspase-3/7 in HCT-116 cells most probably by tumor necrosis factor-alpha (TNF-α) independent intrinsic pathway and significantly inhibited in vitro synthesis of cytokines, interleukin-1 (IL-1) and TNF-α in human macrophages (U937 cells). In a cell-free system, both the compounds inhibited cyclooxygenase (COX) activities, with III being more selective towards COX-2. The results revealed that III has strong antiproliferative property selectively against colorectal tumor cells which could be attributed to its pro-apoptotic and anti-inflammatory abilities.

Synthesis and biological evaluation of a novel class of coumarin derivatives

In this study, several novel coumarin derivatives, 7-hydroxy-2-oxo-2H-chromene-3-carboxyl-Trp-Trp-AA-OBzl compounds, were designed and synthesized as potential anticancer agents. Their in vitro cytotoxic activities were evaluated using methylthiazoltetrazolium (MTT) assay. The anti-tumor activity of the newly coumarin derivatives was determined in a S180 bearing mouse model and some of the compounds demonstrated tumor growth inhibition similar to the positive control, doxorubicin. Compared to doxorubicin, most of the compounds exhibited enhanced immunologic function suggesting a relatively minor toxic effect. The intercalation of the coumarin derivatives synthesized with calf thymus (CT) DNA was also studied.

Benzyl-substituted metallocarbene antibiotics and anticancer drugs

Benzyl-substituted metallocarbene compounds synthesised by our group and others during the past 5 years give a new perspective on their activity as antibiotic and antitumoral drugs. N-heterocyclic carbenes containing an imidazole core were functionalised and their transition metal complexes (M = Ag, Au, Cu, Ru) have shown promising antibacterial as well as anticancer activity in vitro and in vivo. IC50 values in the nanomolar region or antibacterial activity comparable to conventional antibiotics lead the way towards novel drug candidates.

Lanthanide and transition metal complexes of bioactive coumarins: molecular modeling and spectroscopic studies

The present paper summarizes theoretical and spectroscopic investigations on a series of active coumarins and their lanthanide and transition metal complexes with application in medicine and pharmacy. Molecular modeling as well as IR, Raman, NMR and electronic spectral simulations at different levels of theory were performed to obtain important molecular descriptors: total energy, formation energy, binding energy, stability, conformations, structural parameters, electron density distribution, molecular electrostatic potential, Fukui functions, atomic charges, and reactive indexes. The computations are performed both in gas phase and in solution with consideration of the solvent effect on the molecular structural and energetic parameters. The investigations have shown that the advanced computational methods are reliable for prediction of the metal-coumarin binding mode, electron density distribution, thermodynamic properties as well as the strength and nature of the metal-coumarin interaction (not experimentally accessible) and correctly interpret the experimental spectroscopic data. Known results from biological tests for cytotoxic, antimicrobial, anti-fungal, spasmolytic and anti-HIV activities on the studied metal complexes are reported and discussed.

Anti-proliferative and anti-tumor activity of silver(I) compounds

Silver is proving to have a number of medicinal applications; as an antiseptic, an antibacterial, and an anti-inflammatory, while any biological role for it is currently unknown. Silver compounds and their therapeutic potentials are under consideration from many research groups, while a number of early reviews recording the advances of silver(I) chemistry are also available. However there is no recent report on the screening for the antitumor potential of silver(I) compounds. This review focuses upon results obtained on the anti-proliferative activity of silver compounds in the past years. This survey shows that silver(I) complexes containing various type of ligands such as carboxylic acids, amino acids, nitrogen, phosphorus or sulfur donor ligands, exhibit selectivity against a variety of cancer cells. The role of the coordination number, which is related to either the stability or hydrophilicity-lipophilicity of a complex, is not clearly elucidated within this review.

Vibrational spectra, structural conformations, scaled quantum chemical calculations and NBO analysis of 3-acetyl-7-methoxycoumarin

The powder form NIR-FT Raman and FT-IR spectra of 3-acetyl-7-methoxycoumarin (3A7MC) have been recorded in the regions 4000-400 and 3500-100 cm(-1), respectively. The equilibrium geometry, vibrational frequencies, band intensities, NMR spectra, NBO analysis and UV-Vis spectral studies of the most stable conformer have been calculated by density functional B3LYP method with the 6-311G(d,p) basis set. A complete vibrational analysis has been attempted on the basis of experimental infrared and Raman spectra, the calculated wavenumber and intensity of the vibrational bands and the potential energy distribution over the internal coordinates. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping the electron density isosurface with electrostatic potential surfaces (ESP). Natural bond orbital analysis has been carried out to understand the nature of different interactions responsible for the electron delocalization and the intramolecular charge transfer between the orbitals (n→π(∗), n→σ(∗), π→π(∗)).