Fine-tuning the cytotoxicity of ruthenium(II) arene compounds to enhance selectivity against breast cancers.

Ruthenium-based complexes have been suggested as promising anticancer drugs exhibiting reduced general toxicity compared to platinum-based drugs. In particular, Ru(η6-arene)(PTA)Cl2 (PTA = 1,3,5-triaza-7-phosphaadamantane), or RAPTA, complexes have demonstrated efficacy against breast cancer by suppressing metastasis, tumorigenicity, and inhibiting the replication of the human tumor suppressor gene BRCA1. However, RAPTA compounds have limited cytotoxicity, and therefore comparatively high doses are required. This study explores the activity of a series of RAPTA-like ruthenium(II) arene compounds against MCF-7 and MDA-MB-231 breast cancer cell lines and [Ru(η6-toluene)(PPh3)2Cl]+ was identified as a promising candidate. Notably, [Ru(η6-toluene)(PPh3)2Cl]Cl was found to be remarkably stable and highly cytotoxic, and selective to breast cancer cells. The minor groove of DNA was identified as a relevant target.

Anticancer ruthenium(II) tris(pyrazolyl)methane complexes with bioactive co-ligands.

In comparison with RuII-arene compounds, the medicinal potential of homologous RuII-tpm compounds [tpm = tris(pyrazolyl)methane] is underexplored. Pyridine, 4-pyridinemethanol and four functionalized pyridines, synthesized from the esterification of 4-pyridinemethanol with bioactive carboxylic acids (i.e., ethacrynic acid, ibuprofen, flurbiprofen and naproxen), react with the precursor [RuCl(κ3-tpm)(PPh3)2]Cl (1) to afford [RuCl(κ3-tpm)(PPh3)(L)]Cl (2-7, L = pyridine ligand), in 78-91% yields. All products were fully characterized by HR-ESI mass spectrometry, IR and multinuclear NMR spectroscopy and the solid-state structures of two of the complexes, i.e. where L = pyridine and 4-pyridinemethanol, were ascertained by single crystal X-ray diffraction. The {Ru-tpm-PPh3} assembly is stable in D2O and in biological medium (DMEM) at 37 °C, with a tendency to slowly dissociate the pyridine ligand. The antiproliferative activity of the complexes was assessed on the cancerous A2780 and A2780cisR cell lines, and the nontumoral HEK 293T cell line; moreover inhibition assays were carried out on the complexes towards COX-2 and GSTP1 enzymes.

Automated approach for the evaluation of glutathione-S-transferase P1-1 inhibition by organometallic anticancer compounds.

A novel automated method based on sequential injection analysis (SIA), a non-segmented flow injection technique, was developed to evaluate glutathione S-transferase P1-1 (GST P1-1) activity in the presence of organometallic complexes with putative anticancer activity. The assay is based on the reaction of L-glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB) in the presence of GST P1-1 to afford the GS-DNB conjugate and the reaction may be monitored by an increase in absorbance at 340 nm. A series of ruthenium, iron, osmium and iridium complexes were evaluated as GST P1-1 inhibitors by evaluating their half-maximal inhibitory concentration (IC50). An iridium compound displays the lowest IC50 value of 6.7 ± 0.7 µM and an iron compound displays the highest IC50 value of 275 ± 9 µM. The SIA method is simple to use, robust, reliable, and efficient and uses fewer reagents than batch methods and each analysis takes only 5 minutes.

Automatic Identification of Myeloperoxidase Natural Inhibitors in Plant Extracts.

The aim of this study is the development of an automated method for myeloperoxidase activity evaluation and its application in testing the inhibitory action of different plant extracts on the activity of the enzyme. This enzyme has its concentration increased in inflammatory and infectious processes, so it is a possible target to limit these processes. Therefore, an automatic sequential in-jection analysis (SIA) system was optimized and demonstrated that it is possible to obtain results with satisfactory accuracy and precision. With the developed method, plant extracts were studied, as promising candidates for MPO inhibition. In the group of selected plant extracts, IC50 values from 0.029 ± 0.002 mg/mL to 35.4 ± 3.5 mg/mL were obtained. Arbutus unedo L. proved to be the most inhibitory extract for MPO based on its phenolic compound content. The coupling of an automatic SIA method to MPO inhibition assays is a good alternative to other conventional methods, due to its simplicity and speed. This work also supports the pharmacological use of these species that inhibit MPO, and exhibit activity that may be related to the treatment of infection and inflammation.

A Strategy to Conjugate Bioactive Fragments to Cytotoxic Diiron Bis(cyclopentadienyl) Complexes.

A series of bioactive molecules were synthesized from the condensation of aspirin or chlorambucil with terminal alkynes bearing alcohol or amine substituents. Insertion of the resulting alkynes into the iron-carbyne bond of readily accessible diiron bis(cyclopentadienyl) µ-aminocarbyne complexes, [1a,b]CF3SO3, afforded novel diiron complexes with a bridging vinyliminium ligand, [2-10]CF3SO3, functionalized with a bioactive moiety. All compounds were characterized by elemental analysis and IR and multinuclear NMR spectroscopy and in three cases by single-crystal X-ray diffraction. Moreover, the D2O solubility, stability in D2O and cell culture media, and octanol-water partition coefficients of diiron complexes were determined spectroscopically. The cytotoxicity of the complexes was assessed in the tumorigenic A2780 and A2780cisR and the nontumorigenic HEK 293T cell lines. Some complexes exhibit high potency and the ability to overcome resistance in A2780cisR cells (aspirin complexes) or high selectivity relative to HEK 293T cells (chlorambucil complexes). Further studies indicate that the complexes significantly trigger intracellular ROS production, irrespective of the nature of the bioactive fragment. DNA alkylation and protein binding studies were also undertaken.

Automatic evaluation of cyclooxygenase 2 inhibition induced by metal-based anticancer compounds.

An automatic methodology based on micro sequential injection analysis coupled to a lab-on-valve system (termed µSIA-LOV) was developed and used to determine the ability of metal-based anticancer compounds to inhibit cyclooxygenase 2 (COX-2) activity. COX-2 may be involved in pathogenesis of cancer and it is overexpressed in several types of solid tumors. Since platinum-based compounds are extensively used in the treatment of cancer, and ruthenium compounds are considered as promising candidates for next generation of non-targeted anticancer drugs, it is interesting to establish whether COX-2 inhibition is relevant to their mode of action. The µSIA-LOV system was optimized and the IC50 values of each compound were calculated. All the results present RSD values less than 2.5%. IC50 values of 9.7 ±â€¯0.6 µM to 207 ±â€¯3 µM were obtained, with the most active inhibitor for COX-2 being rofecoxib with the metal compounds exhibiting IC50 values in the range 13.7 ±â€¯1.6 to 207 ±â€¯3. The results obtained in this work provide significant information about the mechanism of the studied compounds, mostly ruthenium-based compounds, and the role of COX-2 in their mode of action. Moreover, this work confirmed the potential of the µSIA-LOV system as a simple, versatile, robust, and rapid analytical tool for automating the determination of IC50 values of metal-based compounds.

Evaluation of Ionic Liquids and Ionic Liquids Active Pharmaceutical Ingredients Inhibition in Elastase Enzyme Activity.

Human neutrophil elastase (HNE) is used as diagnostic biomarker for inflammation/infection. In this work, 10 ionic liquids (ILs) and 11 ionic liquids active pharmaceutical ingredients (ILs-APIs) were tested to evaluate the inhibition effect on the activity of porcine pancreatic elastase enzyme, frequently employed as a model for HNE. The insertion of ionic liquids in some drugs is useful, as the insertion of ILs with inhibitory capacity will also slow down all processes in which this enzyme is involved. Therefore, a spectrophotometric method was performed to the determination of EC50 values of the compounds tested. EC50 values of 124 ± 4 mM to 289 ± 11 mM were obtained, with the most toxic IL for elastase being tetrabutylammonium acetate and the least toxic 1-butyl-3-methylimidazolium acetate. Moreover, sodium salicylate (raw material) presented the lower and benzethonium bistriflimide the higher EC50 when compared with all the IL-APIs tested. This work provides significant information about the effect of the studied IL and IL-APIs in elastase enzyme activity.

Bis-conjugation of Bioactive Molecules to Cisplatin-like Complexes through (2,2'-Bipyridine)-4,4'-Dicarboxylic Acid with Optimal Cytotoxicity Profile Provided by the Combination Ethacrynic Acid/Flurbiprofen.

A facile route to PtII complexes doubly functionalized with bioactive molecules through a bipyridine-type ligand is described. Initially, ligands LEE (containing two ethacrynic acid units), LEF (ethacrynic acid+flurbiprofen) and LEB (ethacrynic acid+biotin) were obtained in moderate to good yields from 2,2'-bipyridine-4,4'-dicarboxylic acid. Subsequent reaction of the ligands with [PtCl2 (DMSO)2 ] afforded complexes [PtCl2 (LEE )] (2), [PtCl2 (LEF )] (3) and [PtCl2 (LEB )] (4) in high yields. All compounds were fully characterized by analytical and spectroscopic methods. Complexes 2-4 are highly stable in water/DMSO solution at 37 °C after 72 h, whereas progressive release of the bioactive fragments was detected in a cell culture medium. The compounds were assessed for their in vitro antiproliferative activity towards tumorigenic A2780, A2780cisR and Y79 cells and non-tumourigenic HEK293 cells. In particular, the combination of ethacrynic acid and flurbiprofen in 3 overcomes cisplatin-based resistance and provides strong cancer cell selectivity. Enzyme inhibition assays on human GST P1 and human COX-2 and cross-experiments with complex 1, analogous to 2-4 but lacking bio-groups, revealed a clear synergy between the PtII frame and the bioactive organic components.

Automatic methodologies to perform loading and release assays of anticancer drugs from mesoporous silicon nanoparticles.

Two automatic methodologies were developed to perform the loading and release assays of drugs from porous silicon (PSi) nanoparticles. 5-Fluorouracil (5-FU) was selected as a model drug, and different functionalized PSi nanoparticles were used. While for drug loading studies the reproducible characteristics of flow systems were explored regarding mixture and volumes taken, in the drug release flow methodology versatility in accommodating different devices around the valve were tested. Fluorescent properties of 5-FU were used with detection limit of 9 × 10-4 mg L-1 and a linear response up to 5 mg L-1 The drug loading and release procedures were optimized in sequential injection analysis (SIA) systems obtaining a huge economy regarding the time spent (4 min towards 2 h). Batch and SIA methods were tested and compared for the different behaviours of the PSi nanoparticles towards both methodologies and no noteworthy differences were obtained with Student's t-test for loading with a calculated t value of 2.04 showing the absence of statistical differences. All the results present a RSD less than 10%. So, the developed automatic methodologies are a viable alternative to load drugs and to study the release profiles from PSi nanoparticles.

The role of ionic liquids in the biocatalytic evaluation of bisphenol levels as contaminant: an automatic approach.

An automatic assay was developed that is intended to be a generic tool for evaluation of a horseradish peroxidase activity in different ionic liquids (ILs). Ionic liquids with different characteristics were used and their effects on the enzymatic reaction, were compared with those obtained with conventional organic solvents. In addition, ILs were tested as solvents for the enzyme substrate (bisphenol A (BPA)). ILs were shown to be a good alternative to conventional organic solvents from either the effect on enzymatic activity or the solubilization of bisphenol. Since bisphenol A is an endocrine disruptor frequently used in plastic industries, it was also applied the developed enzymatic methodology for quantification of this compound in real beverage samples. To increase the sensitivity (already increased by the use of an IL) and the selectivity of the methodology, a sample pre-treatment using a molecular recognition solid phase extraction was applied. Finally, the methodology presented detection and quantification limits of 7.73 × 10-4 and 1.29 × 10-3 mmol L-1 and a linear range up to 1.00 mmol L-1, allowing accurate and reliable quantifications of bisphenol in beer and cola drink samples. This work confirmed the potential of a sequential injection analysis (SIA) system as a simple, versatile, robust, and rapid analytical tool for automating enzymatic assays in ILs medium and, at the same time, showed it to be a relevant automatic alternative for routine determinations of bisphenol A in food samples.

Manual or automated measuring of antipsychotics' chemical oxygen demand.

Antipsychotic (AP) drugs are becoming accumulated in terrestrial and aqueous resources due to their actual consumption. Thus, the search of methods for assessing the contamination load of these drugs is mandatory. The COD is a key parameter used for monitoring water quality upon the assessment of the effect of polluting agents on the oxygen level. Thus, the present work aims to assess the chemical oxygen demand (COD) levels of several typical and atypical antipsychotic drugs in order to obtain structure-activity relationships. It was implemented the titrimetric method with potassium dichromate as oxidant and a digestion step of 2h, followed by the measurement of remained unreduced dichromate by titration. After that, an automated sequential injection analysis (SIA) method was, also, used aiming to overcome some drawbacks of the titrimetric method. The results obtained showed a relationship between the chemical structures of antipsychotic drugs and their COD values, where the presence of aromatic rings and oxidable groups give higher COD values. It was obtained a good compliance between the results of the reference batch procedure and the SIA system, and the APs were clustered in two groups, with the values ratio between the methodologies, of 2 or 4, in the case of lower or higher COD values, respectively. The SIA methodology is capable of operating as a screening method, in any stage of a synthetic process, being also more environmentally friendly, and cost-effective. Besides, the studies presented open promising perspectives for the improvement of the effectiveness of pharmaceutical removal from the waste effluents, by assessing COD values.

Environmental Impact of Ionic Liquids: Automated Evaluation of the Chemical Oxygen Demand of Photochemically Degraded Compounds.

A novel automated fluorimetric technique was developed for the assessment of the chemical oxygen demand (COD) of ionic liquids (ILs) and combined with a photodegradation step to promote IL degradation. The method was implemented on a sequential injection analysis (SIA) system and is based on the reduction of cerium(IV) in the presence of irradiated ILs. Compounds incorporating the chloride anion were found to exhibit higher COD values and 1-butyl-3-methylimidazolium chloride ([bmim]+ [Cl]- ), 1-butyl-1-methylpyrrolidinium chloride ([bmpyr]+ [Cl]- ), and1-hexyl-3-methylimidazolium chloride ([hmim]+ [Cl]- ) also exhibited considerable photodegradability, whereas the cholinium cation and methanesulfonate and tetrafluoroborate anions showed resistance to photolysis. The developed methodology proved to be a simple, affordable, and robust method, showing good repeatability under the tested conditions (rsd <3.5 %, n=10). Therefore, it is expected that the developed approach can be used as a screening method for the preliminary evaluation of compounds' potential impact in the aquatic field. Additionally, the photolysis step presents an attractive option to promote degradation of ILs prior to their release into wastewater.

Assessment of ionic liquids' toxicity through the inhibition of acylase I activity on a microflow system.

Acylase I (ACY I) plays a role in the detoxication and bioactivation of xenobiotics as well in other physiological functions. In this context, an automated ACY I assay for the evaluation of ionic liquids' (ILs) toxicity was developed. The assay was implemented in a sequential injection analysis (SIA) system and was applied to eight commercially available ILs. The SIA methodology was based on the deacetylation of N-acetyl-l-methionine with production of l-methionine, which was determined using fluorescamine. ACY I inhibition in the presence of ILs was monitored by the decrease of fluorescence intensity. The obtained results confirmed the influence of ILs' structural elements on its toxicity and revealed that pyridinium and phosphonium cations, longer alkyl side chains and tetrafluoroborate anion displayed higher toxic effect on enzyme activity. The developed methodology proved to be robust and exhibited good repeatability (RSD < 1.3%, n = 10), leading also to a reduction of reagents consumption and effluents production. Thus, it is expected that the proposed assay can be used as a novel tool for ILs' toxicity screening.