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The effects of ferrocene (Fc) and ferrocenium (Fc+) induced in triple negative human breast cancer MCF-7 cells were explored by immunofluorescence, flow cytometry, and transmission electron microscopy analysis. The different abilities of Fc and Fc+ to produce reactive oxygen species and induce oxidative stress were clearly observed by activating apoptosis and morphological changes after treatment, but also after tests performed on the model organism D. discoideum, particularly in the case of Fc+. The induction of ferroptosis, an iron-dependent form of regulated cell death driven by an overload of lipid peroxides in cellular membranes, occurred after 2 h of treatment with Fc+ but not Fc. However, the more stable Fc showed its effects by activating necroptosis after a longer-lasting treatment. The differences observed in terms of cell death mechanisms and timing may be due to rapid interconversion between the two oxidative forms of internalized iron species (from Fe2+ to Fe3+ and vice versa). Potential limitations include the fact that iron metabolism and mitophagy have not been investigated. However, the ability of both Fc and Fc+ to trigger different and interregulated types of cell death makes them suitable to potentially overcome the shortcomings of traditional apoptosis-mediated anticancer therapies. [ABSTRACT FROM AUTHOR]

The complex [PtCl2(cyclohexane-1R,2R-diamine)] has been combined in a Pt(IV) molecule with two different bioactive molecules (i.e., the histone deacetylase inhibitor 2-propylpentanoic acid or valproic acid, VPA, and the potential antimetastatic molecule 4-isopropenylcyclohexene-1-carboxylic acid or perillic acid, PA) in order to obtain a set of multiaction or multitarget antiproliferative agents. In addition to traditional thermal synthetic procedures, microwave-assisted heating was used to speed up their preparation. All Pt(IV) complexes showed antiproliferative activity on four human colon cancer cell lines (namely HCT116, HCT8, RKO and HT29) in the nanomolar range, considerably better than those of [PtCl2(cyclohexane-1R,2R-diamine)], VPA, PA, and the reference drug oxaliplatin. The synthesized complexes showed pro-apoptotic and pro-necrotic effects and the ability to induce cell cycle alterations. Moreover, the downregulation of histone deacetylase activity, leading to an increase in histone H3 and H4 levels, and the antimigratory activity, indicated by the reduction of the levels of matrix metalloproteinases MMP2 and MMP9, demonstrated the multiaction nature of the complexes, which showed biological properties similar to or better than those of VPA and PA, but at lower concentrations, probably due to the lipophilicity of the combo molecule that increases the intracellular concentration of the single components (i.e., [PtCl2(cyclohexane-1R,2R-diamine)], VPA and PA). [ABSTRACT FROM AUTHOR]

The biological behavior of the axially unsymmetric antitumor prodrug (OC-6-44)-acetatodiamminedichloridohydroxidoplatinum(IV), 2, was deeply investigated and compared with that of analogous symmetric Pt(IV) complexes, namely, dihydroxido 1 and diacetato 3, which have a similar structure. The complexes were tested on a panel of human tumor cell lines. Complex 2 showed an anomalous higher cytotoxicity (similar to that of cisplatin) with respect to their analogues 1 and 3. Their reduction potentials, reduction kinetics, lipophilicity, and membrane affinity are compared. Cellular uptake and DNA platination of Pt(IV) complexes were deeply investigated in the sensitive A2780 human ovarian cancer cell line and in the corresponding resistant A2780cisR subline. The unexpected activity of 2 appears to be related to its peculiar cellular accumulation and not to a different rate of reduction or a different efficacy in DNA platination and/or efficiency in apoptosis induction. Although the exact mechanism of cell uptake is not fully deciphered, a series of naïve experiments indicates an energy-dependent, carrier-mediated transport: the organic cation transporters (OCTs) are the likely proteins involved. [ABSTRACT FROM AUTHOR]

Microwave-assisted synthesis is considered environmental-friendly and, therefore, in agreement with the principles of green chemistry. This form of energy has been employed extensively and successfully in organic synthesis also in the case of metal-catalyzed synthetic procedures. However, it has been less widely exploited in the synthesis of metal complexes. As microwave irradiation has been proving its utility as both a time-saving procedure and an alternative way to carry on tricky transformations, its use can help inorganic chemists, too. This review focuses on the use of microwave irradiation in the preparation of transition metal complexes and organometallic compounds and also includes new, unpublished results. The syntheses of the compounds are described following the group of the periodic table to which the contained metal belongs. A general overview of the results from over 150 papers points out that microwaves can be a useful synthetic tool for inorganic chemists, reducing dramatically the reaction times with respect to traditional heating. This is often accompanied by a more limited risk of decomposition of reagents or products by an increase in yield, purity, and (sometimes) selectivity. In any case, thermal control is operative, whereas nonthermal or specific microwave effects seem to be absent. [ABSTRACT FROM AUTHOR]

Octahedral Pt(IV) prodrugs are an effective way to combine cisplatin-like moieties and a second drug to obtain selective and stimuli responsive bifunctional antiproliferative compounds. Recently, two bifunctional Pt(IV) complexes have shown interesting in vitro and in vivo effects in glioblastoma, the most aggressive primary brain tumor. An interesting observation indicates that 4,5-dihydroxy-9,10-dioxo-9,10- dihydroanthracene-2-carboxylic acid (rhein) can inhibit in vivo glioma tumor progression. Furthermore, a prodrug in which cisplatin was combined with two molecules of rhein showed a potency higher than that of cisplatin toward cisplatin-resistant lung carcinoma cells. However, the high lipophilicity of this type of complex affects their solubility and bioavailability. To overcome these limits, in the present work, three Pt (IV) derivatives were obtained by differently linking one molecule of rhein and one acetato ligand at the axial position to a cisplatin core. The complexes proved to be similar to or more potent than the parent cisplatin and rhein, and the reference drug temozolomide on two human glioblastoma cell lines (U87-MG and T98G). They retained their activity under hypoxia and caused a significant reduction in the motility of both cell lines, which can be related to their ability to inhibit MMP2 and MMP9 matrix metalloproteinases. Finally, physicochemical and computational studies indicated that these Pt(IV) derivatives are more prone than rhein to cross the blood--brain barrier. [ABSTRACT FROM AUTHOR]

Platinum(II)-based drugs are widely used for the treatment of solid tumors, especially in combination protocols. Severe side effects and occurrence of resistance are the major limitations to their clinical use. To overcome these drawbacks, a plethora of Pt(IV) derivatives, acting as anticancer prodrugs, have been designed, synthesized and preclinically (often only in vitro) tested. Here, we summarize the recent progress in the development and understanding of the chemical properties and biochemical features of these Pt(IV) prodrugs, especially those containing bioactive molecules as axial ligands, acting as multi-functional agents. Even though no such prodrugs have been yet approved for clinical use, many show encouraging pharmacological profiles. Thus, a better understanding of their features is a promising approach towards improving the available Pt-based anticancer agents. [ABSTRACT FROM AUTHOR]

The possibility of spontaneous self-assembly of dicarboxylato Pt(IV) prodrugs and the consequences on their uptake in cancer cells have been evaluated in different aqueous solutions. Four Pt(IV) complexes, namely, (OC-6-33)-diacetatodiamminedichloridoplatinum(IV), Ace, (OC-6-33)-diamminedibutanoatodichloridoplatinum(IV), But, (OC-6-33)-diamminedichloridodihexanoatoplatinum(IV), Hex, and (OC-6-33)-diamminedichloridodioctanoatoplatinum(IV), Oct, have been dispersed in i) milliQ water, ii) phosphate buffered saline, and iii) complete cell culture media (RPMI 1640 or DMEM) containing fetal bovine serum (FBS). The samples have been analyzed by dynamic light scattering (DLS) to measure the size and distribution of the nanoparticles possibly present. The zeta potential offered an indication of the stability of the resulting aggregates. In the case of the most lipophilic compounds of the series, namely, Oct and to a lesser extent Hex, the formation of nanosized aggregates has been observed, in particular at the highest concentration tested (10 μM). The cell culture media had the effect to disaggregate these nanoparticles, mainly by virtue of their albumin content, able to interact with the organic chains via noncovalent (hydrophobic) interactions. For Oct, at the highest concentration employed for the uptake tests (10 μM), the combination between passive diffusion and endocytosis of the self-assembled nanoparticles makes the cellular uptake higher than in the presence of passive diffusion only. During the study of cellular uptake on A2780 ovarian cancer cells pretreated with cytochalasin D, a statistically significant inhibition of endocytosis was observed for Oct. In these experimental conditions, the relationship between uptake and lipophilicity becomes almost linear instead of exponential. Since Oct anticancer prodrug is active at nanomolar concentrations, where the aggregation in culture media is almost abolished, this phenomenon should not significantly impact its antiproliferative activity. [ABSTRACT FROM AUTHOR]

The Pt(IV) complexes based on (SP-4-2)-dichlorido(cyclohexane-1,4-diamine)platinum(II) (kiteplatin) and the histone deacetylase inhibitor 2-(2-propynyl)octanoic acid (POA) were investigated. Since POA contains a chiral carbon, all the possible Pt(IV) isomers were prepared and characterized, and their antiproliferative activity on six cancer cell lines was compared with that of the corresponding Pt(IV) complexes containing the cyclohexane-1R,2R-diamine equatorial ligand. To justify the very good antiproliferative activity (nanomolar IC50), the polarity, lipophilicity, permeability, and cell accumulation of the complexes were studied. Overall, the two series of Pt(IV) complexes showed similar cell penetration properties, being significantly better than that of the Pt(II) reference compounds. Finally, a representative compound of the whole set of complexes (i.e., that based on cyclohexane-1R,2R-diamine and racemic POA) was tested in vivo on mice bearing Lewis lung carcinoma, showing good tumor growth inhibition with negligible body weight loss. [ABSTRACT FROM AUTHOR]

Two Pt(IV) conjugates containing one or two molecules of perillic acid (4-isopropenylcyclohexene-1-carboxylic acid), an active metabolite of limonene, were synthesized both with traditional and microwave-assisted methods and characterized. Their antiproliferative activity was tested on a panel of human tumor cell lines. In particular, cis,cis,trans-[PtIVCl2(NH3)2(perillato)2] exhibited excellent antiproliferative and antimetastatic activity on A-549 lung tumor cells at nanomolar concentrations. A number of in vitro biological tests were performed to decipher some aspects of its mechanism of action, including transwell migration and invasion as well as wound healing assay. [ABSTRACT FROM AUTHOR]

• Pt(IV) complexes are antitumor prodrugs, activated by reduction to Pt(II) metabolites. • Multi-action Pt(IV) conjugates contain two or more moieties acting synergistically. • These agents can be designed to overcome intrinsic or acquired chemoresistance. • Pt(IV) complexes containing inhibitors of tumor-related mechanisms are reported. Platinum(IV) complexes are particularly appealing as prodrugs since their relative inertness, and consequent low toxicity outside the cell is matched by their high activity inside the tumor cells upon reduction to their corresponding Pt(II) counterparts. Synthetic routes to such systems, with particular emphasis on the bioactivity of the removable axial ligands, are described herein. The kinetics and mechanisms of these reductive elimination processes are still not completely unraveled, and many questions remain unresolved. We here present some of the more relevant examples of multi-action Pt(IV) complexes often grouped around their prototypal prodrugs (i.e. , mitaplatin and mitochondria-targeted complexes, ethacraplatin and glutathione-S-transferase-targeted complexes, asplatin or platin-A and inhibitors of cyclooxygenases). In addition, Pt(IV) conjugates with histone deacetylase inhibitors (HDACi) and "true" multiple-action complexes are exhaustively discussed. These Pt(IV) conjugates contain adjuvant agents able to inhibit some specific (typically enzymatic) mechanism characteristic of, or more active in, tumor cells. These agents are able to act synergistically or at least additively with cisplatin and its congeners and overcome intrinsic or acquired chemoresistance. Finally, we emphasize the need for a multidisciplinary approach in the battle against cancer using metallo-drugs by involving not only inorganic chemists, but also biochemists, molecular biologists and, of course, clinicians. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Diels–Alder reaction is a powerful tool to design drug delivery systems. • Two Pt(IV) complexes containing 2-maleimido acetic acid as axial ligand are proposed. • Clickability of the maleimide-containing Pt(IV) complexes was demonstrated with furan. • As a proof-of-concept, the Pt(IV) conjugates were appended to furan-modified SiO 2 nanoparticles. Abstract Pt(IV) complexes are considered to act as antitumor prodrugs and their in vivo activity can be improved exploiting drug targeting and delivery strategies. With a view to such applications, the maleimide-containing ligand 2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)acetic acid was used to produce the cisplatin-based Pt(IV) complexes (OC -6-44)-diamminedichlorido(ethanolato)(2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)acetato)platinum(IV) and (OC -6-44)-acetatodiamminedichlorido(2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)acetato)platinum(IV). These complexes underwent Diels-Alder reaction with furan, used as a model molecule to set up the experimental conditions, at ambient temperature up to 50 h, with limited decomposition. Finally, the reaction between the maleimide-containing Pt(IV) complexes and silica nanoparticles decorated with furan were successfully used as a proof-of-concept to demonstrate the clickability of functionalized vectors for drug delivery. [ABSTRACT FROM AUTHOR]

Abstract Nonporous silica nanoparticles with an external shell containing the 3‑aminopropyl arm (SiNP) were further decorated with alginic acid (SiNP-ALG) as a potential biocompatible delivery system for Pt antitumor agents. Such particles were coupled with the prodrug (OC ‑6‑44)‑acetato(β‑alaninato)diamminedichloridoplatinum(IV), 1 , through the formation of amide bonds between the pendant carboxylate groups on SiNP-ALG and the free amino group of the complex. Cytosol extracted from tumor cells was able to quickly and efficiently reduce the Pt(IV) prodrug, and produces the active metabolite cisplatin. SiNP-ALG-Pt conjugate was more active than both cisplatin and 1 , due to its more efficient cell uptake, whereas the SiNP-ALG unplatinated nanoparticles were deprived of any nonspecific toxicity. Graphical abstract Amino-decorated nonporous silica nanoparticles were further coated with alginic acid to produce a potential biocompatible delivery system for Pt(IV) antitumor prodrug (OC ‑6‑44)‑acetato(β‑alaninato)diamminedichloridoplatinum(IV), through the formation of amide bonds. The conjugate was more active than both cisplatin and the Pt(IV) precursor, due to its more efficient cell uptake. Unlabelled Image Highlights • Synthesis of nonporous silica nanoparticles coated with alginic acid • Delivery system for the antitumor Pt(IV) prodrug • Higher activity of the conjugate vs free Pt(IV) complex or cisplatin [ABSTRACT FROM AUTHOR]

Multi-action cisplatin-based mono- (1) and di-clofibric acid (2) Pt(iv) “combo” derivatives were synthesized via both traditional and microwave assisted procedures. The two complexes offered very good performances (IC50 values in a nanomolar range) on a panel of human tumor cell lines, including the highly chemoresistant malignant pleural mesothelioma ones. Moreover, both 1 and 2 bypass the cisplatin resistance. Indeed, cisplatin and clofibric acid, the metabolites of the Pt(iv) → Pt(ii) intracellular reduction, proved to act synergistically. The adjuvant action of clofibric acid relies on the activation of peroxisome proliferator-activated receptor α (PPARα) that, in turn, decreases the level of Hypoxia-Inducible Factor-1α. Both compounds induced extensive apoptosis in tumor cells, also via oxidative stress. Finally, 2 exhibited excellent performances also under the hypoxic conditions typical of solid tumors, where cisplatin is less effective. [ABSTRACT FROM AUTHOR]

New chitosan derivatives modified with (3-carboxypropyl)trimethylammonium chloride (1) and coupled with (OC-6-44)-diammine(4-carboxypropanoato)dichloridoethanolatoplatinum(IV) (2), were synthesized and their preliminary biological evaluation carried out in human tumor cells. Some of these derivatives were also loaded with a chelating ligand (3) that was derived from bis(quinolin-2-ylmethyl)amine to obtain chitosan-based nanoparticles for an EPR-mediated delivery of Pt(IV) prodrugs and Re(I) tricarbonyl complexes (4), to explore a multimodal theranostic approach to cancer. The cytotoxicity of the different chitosan conjugates (C12, C123, and C1234), carrying different combinations of the Pt(IV) complex, the chelator and the Re(I) complex, was evaluated in the A2780 human ovarian cancer cell line using the MTT assay. The Pt(IV)-containing nanosystems showed low to moderate cytotoxic activity (IC50 values in the range 13.5-33.7 μM) and was comparable to that found for the free Pt(IV) complex (IC50 = 13.7 μM). Therefore, the Pt(IV)-chitosan conjugation did not enhance the cytotoxic activity of the Pt(IV) prodrug, which certainly reflects the inefficient cellular uptake of the nanoconjugates. Nevertheless, a clearer view of their potential for the delivery of anticancer agents requires further in vivo tests because the EPR effect increases extravasation and retention within the tumor tissue, not necessarily within the tumor cells. [ABSTRACT FROM AUTHOR]

The design, synthesis, characterization and biological properties of a Pt(iv) complex containing the very active inhibitor of histone deacetylase (2-propynyl)octanoic acid, POA, as an axial ligand are reported here. The title complex, namely (OC-6-44)-acetatodiamminedichlorido(2-(2-propynyl)octanoato)platinum(iv), 1, containing POA in racemic or in enantiomeric forms, was one/two orders of magnitude more active than cisplatin, depending on the chemo-sensitivity of the cancer cell lines. Moreover, 1 exhibited similar or even better antiproliferative activity than (OC-6-33)-diamminedichloridobis(2-propylpentanoato)platinum(iv), 2, containing two molecules of the well-known histone deacetylase inhibitor 2-propylpentanoic (valproic) acid. The high potency of 1 is likely due to its high cellular accumulation and to the synergism between the DNA-damaging cisplatin and the histone deacetylase inhibitor POA, both released upon the intracellular reduction of 1. Prodrug 1, after oral administration, caused an impressive reduction of the tumor mass (94%) in a model of solid tumor (murine Lewis lung carcinoma), compared to that of the control, whereas (intraperitoneal) cisplatin induced a tumor regression of 75% only. A good accumulation of 1 was observed in the tumor mass. The time course of the body weight attested that cisplatin induced elevated anorexia, whereas treatment with 1 did not induce significant body weight loss throughout the therapeutic experiment. [ABSTRACT FROM AUTHOR]

A small series of Pt(IV) prodrugs containing Gln-like (Gln = glutamine) axial ligands has been designed with the aim to take advantage of the increased demand of Gln showed by some cancer cells (glutamine addiction). In complex 4 the Gln, linked through the α-carboxylic group is recognized by the Gln transporters, in particular by the solute carrier transporter SLC1A5. All compounds showed cellular accumulation, as well as antiproliferative activity, related to their lipophilicity, as already demonstrated for the majority of Pt(IV) prodrugs, that enter cells mainly by passive diffusion. On the contrary, when the Gln concentration in cell medium is near or lower to the physiological value, complex 4 acts as a Trojan horse: it enters SLC1A5-overexpressing cells, where, upon reduction, it releases the active metabolite cisplatin and the Gln-containing ligand, thus preventing any possible extrusion by the L-type amino acid transporter LAT1. This selective mechanism could decrease off-target accumulation of 4 and, consequently, Pt-associated side-effects. [ABSTRACT FROM AUTHOR]

Phenanthriplatin, that is, (SP-4-3)-diamminechlorido(phenanthridine)platinum(II) nitrate, an effective antitumor cationic Pt(II) complex, was loaded on negatively charged dextran sulfate (DS) as a model vector for drug delivery via electrostatic interactions. The free complex and the corresponding conjugate with DS were tested on two standard human tumor cell lines, namely, ovarian A2780 and colon HCT 116, and on several malignant pleural mesothelioma cell lines (namely, epithelioid BR95, mixed/biphasic MG06, sarcomatoid MM98, and sarcomatoid cisplatin-resistant MM98R). The in vitro results suggest that the conjugate releases the active metabolite phenanthriplatin with a biphasic fashion. In these experimental conditions, the conjugate is slightly less active than free phenanthriplatin; but both exhibited antiproliferative potency higher than the reference metallodrug cisplatin and were able to overcome the acquired cisplatin chemoresistance in MM98R cells. [ABSTRACT FROM AUTHOR]

We report studies of a novel series of Pt(iv) complexes exhibiting an asymmetric combination of acetylamido and carboxylato ligands in the axial positions. We demonstrate efficient synthesis of a series of analogues, differing in the alkyl chain length and hence lipophilicity, from a stable acetylamido/hydroxido complex formed by reaction of cisplatin with peroxyacetimidic acid (PAIA). NMR spectroscopy and X-ray crystallography confirm the identity of the resulting complexes, and highlight subtle differences in the structure and stability of acetylamido complexes compared to the equivalent acetato complexes. Reduction of acetylamido complexes, whether achieved chemically or electro-chemically, is significantly more difficult than that of acetate complexes, resulting in lower antiproliferative activity for shorter-chain complexes. For those with longer chains and hence greater cell uptake, this difference is negated and acetylamido complexes are as active as acetato analogues, both exhibiting antiproliferative potency (1/IC50) against A2780 ovarian cancer cells similar to that of cisplatin. [ABSTRACT FROM AUTHOR]

The microwave-assisted synthesis of Pt(II) complexes containing several pyridines (i.e., pyridine L1 , 2-picoline L2 , 3-picoline L3 , 4-picoline L4 , 2,2′-bipyridine L5 ) is reported. For L1 – L5 , the reaction was successful in about 50% yield with all the ligands except L2 . The same method applied to 4,4′-bis(2-morpholinoethoxy)-2,2′-bipyridine ( L6 , a ligand showing interesting antiproliferative properties because of a high DNA affinity), was unsatisfactory. The corresponding complex cis -[PtCl 2 ( L6 )] was obtained only heating at reflux a mixture of [PtCl 2 (1,5-cyclooctadiene)] and L6 in acetonitrile for 24 h. Antiproliferative activity of [PtCl 2 ( L6 )] on four cancer cell lines (ovarian A2780 and its cisplatin-resistant variant A2780cisR, prostate PC3 and breast cancer MDA-MB-231) was compared with that of its ligand and the model complex [PtCl 2 ( L5 )]. These studies showed that [PtCl 2 ( L6 )] has just marginal activity towards the tested cells if compared with cisplatin. [ABSTRACT FROM AUTHOR]

A series of Pt(IV) anticancer prodrug candidates, having the equatorial arrangement of cisplatin and bearing two aliphatic carboxylato axial ligands, has been investigated to prove the relationship between lipophilicity, cellular accumulation, DNA platination and antiproliferative activity on the cisplatin-sensitive A2780 ovarian cancer cell line. Unlike cisplatin, no facilitated influx/efflux mechanism appears to operate in the case of the Pt(IV) complexes under investigation, thus indicating that they enter by passive diffusion. While Pt(IV) complexes having lipophilicity comparable to that of cisplatin (negative values of log P o/w ) exhibit a cellular accumulation similar to that of cisplatin, the most lipophilic complexes of the series show much higher cellular accumulation (stemming from enhanced passive diffusion), accompanied by greater DNA platination and cell growth inhibition. Even if the Pt(IV) complexes are removed from the culture medium in the recovery process, the level of DNA platination remains very high and persistent in time, indicating efficient storing of the complexes and poor detoxification efficiency. [ABSTRACT FROM AUTHOR]

Two small series of Pt(IV) complexes of the general formula cis , cis , trans -[PtA 2 Cl 2 L 2 ] (A = 2 × NH 3 , series 1 , or cyclohexane-1 R ,2 R -diamine, dach, series 2 , L = aromatic carboxylate of different chain length, i.e. –OCO(CH 2 ) n C 6 H 5 , n = 0 ( a ), 1 ( b ), and 2 ( c )) were synthesized and fully characterized, including X-ray structure analysis of one of them. The antiproliferative activity of the complexes was evaluated against a panel of eight human cancer cell lines, proving to be at the nanomolar level for the platinum-sensitive A2780 and at the sub-micromolar level for the chemoresistant mesothelioma cell lines. In contrast with Pt(IV) complexes bearing aliphatic carboxylates, whose antiproliferative potency increases with the number of carbon atoms, a clear structure–activity relationship cannot be drawn in the bis (benzoato) series. The inclusion reaction with cyclodextrins (CDs), a widely accepted approach for drug formulation, was performed in order to obtain adducts able to bypass the limitations imposed by the low water solubility of bis (benzoato) complexes. Phase-solubility tests demonstrated that β-CD was able to efficiently solubilize only the very active prototype [Pt(NH 3 ) 2 Cl 2 (C 6 H 5 COO) 2 ] 1a . Two methods were used to prepare the host–guest inclusion systems ( i.e. , simple solubilization at room temperature of 1a in solution containing excess of β-CD or thermal reaction with subsequent isolation of a solid adduct) and the resulting adducts were tested for cytotoxicity against the cancer cell lines. The presence of β-CD in solution did not decrease the remarkable antitumor activity of 1a , whereas the solid-state inclusion system underwent extensive aggregation, proving to be detrimental for Pt accumulation in the cells and, therefore, overall cytotoxicity. [ABSTRACT FROM AUTHOR]

Pt(IV) complexes are usually prepared by oxidation of the corresponding Pt(II) counterparts, typically using hydrogen peroxide or chlorine. A different way to synthesize asymmetrical Pt(IV) compounds is the oxidative chlorination of Pt(II) counterparts with N-chlorosuccinimide. The reaction between cisplatin cis-[PtCl2(NH3)2], carboplatin, cis-[PtCl2(dach)] and cis-[Pt(cbdc)(dach)] (cbdc = cyclobutane-1,1'-dicarboxylato; dach = cyclohexane-1R,2R-diamine) with N-chlorosuccinimide in ethane-1,2-diol was optimized to produce the asymmetric Pt(IV) octahedral complexes [PtA2Cl(glyc)X2] (A2 = 2 NH3 or dach; glyc = 2-hydroxyethanolato; X2 = 2 Cl or cbdc) in high yield and purity. The X-ray crystal structure of the [Pt(cbdc)Cl(dach)(glyc)] complex is also reported. Moreover, the oxidation method proved to be versatile enough to produce other mixed Pt(IV) derivatives varying the reaction medium. The two trichlorido complexes easily undergo a pH-dependent hydrolysis reaction, whereas the dicarboxylato compounds are stable enough to allow further coupling reactions for drug targeting and delivery via the glyc reactive pendant. Therefore, the coupling reaction between the [Pt(cbdc)Cl(dach)(glyc)] and a model carboxylic acid, a model amine, and selectively protected amino acids is reported. [ABSTRACT FROM AUTHOR]

This article evaluates the efficacy and applicability of bifunctional prodrugs consisting of a six-coordinate Pt(IV) octahedral core and one or more bioactive molecules. The platinum(IV) complexes release upon reduction the corresponding cytotoxic Pt(II) agents and the bioactive molecules, able to inhibit some biochemical mechanisms of cancer growth and/or prevent the deactivation of the Pt(II) metabolites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two Pt(IV) complexes were formulated with Intralipid to evaluate delivery to cancer cells. • Intralipid formulations show an increase in cell accumulation vs. free complexes. • Free complexes were more cytotoxic than their Intralipid formulations. • The presence of Intralipid was not totally detrimental of the potency. • A possible use in vivo of the Pt(IV)-Intralipid formulations should not be excluded. The two Pt(IV) complexes (OC -6–33)-(cyclohexane-1 R ,2 R -diamine)dichloridodiheptanoatoplatinum(IV) (1) and (OC -6–33)-(cyclohexane-1 R ,2 R -diamine)dichloridodioctanoatoplatinum(IV) (2) were formulated with Intralipid® (IL) as a proof-of-concept to evaluate the delivery of lipophilic metal compounds to cancer cells. Negatively charged nanoemulsions ranging from 287 to 312 nm were obtained. The IL formulations show an increase in cancer cell accumulation (A2780 ovarian cancer cells) by a factor 6–7 with respect to the free complexes. In spite of the expected antiproliferative properties, in the cytotoxicity experiments free complexes showed values of the half-maximal inhibitory concentration (IC 50) from 2 to 6 times lower with respect to the IL formulations. However, the presence of IL was not totally detrimental of the potency, that is still in the nanomolar range, and, hence, a possible use in vivo , should not be excluded a priori. [ABSTRACT FROM AUTHOR]

The chemical and biological features of two newly synthesized [PtCl(L)(2-aminonaphthalene)] complexes (L is NH or 2-aminonaphthalene) were compared with those of two already reported enantiomeric complexes of formula [PtCl(DABN)] [DABN is ( R)-1,1′-binaphthyl-2,2′-diamine or ( S)-1,1′-binaphthyl-2,2′-diamine]. Solution behavior, lipophilicity, cytotoxicity with regard to one colorectal (HCT116) and two ovarian (A2780 and A2780Cp8) human carcinoma cell lines, and in vitro DNA- and G-quadruplex-binding properties were evaluated. In particular, the cytotoxicity of [PtCl(NH)(2-aminonaphthalene)] was better than that of cisplatin for all cell lines, and rather resembled that of oxaliplatin. The solution behavior of the whole series of complexes and the absence of an evident relationship between lipophilicity and cytotoxicity seem to suggest that all these experimental parameters are probably smoothed out during the 3-day cytotoxicity experiments and do not strongly affect the half-maximal inhibitory concentrations. The results of electrophoretic studies indicate that different kinds of interaction with DNA can be involved in the mode of action of these complexes, with intercalation in double-stranded DNA and stacking on G-quadruplex DNA being strongly implicated in particular for [PtCl(NH)(2-aminonaphthalene)]. [ABSTRACT FROM AUTHOR]

The biological activity of four cisplatin-like Pt-phosphane complexes, namely, cis-[PtCl2(L)2], L = PPh3, P(Ph)2( p-C6H4-COOH), P(Ph)2(-CH2CH2-COOH) and its succinimidyl ester derivative, has been tested on monolayer cultures of three tumour cell lines (namely, A2780 human ovarian carcinoma and its cisplatin-resistant form A2780Cp8, and human colon adenocarcinoma HCT116). These complexes can undergo intramolecular rearrangements by virtue of their functionalized phosphanes, thereby existing as fully opened (O) or fully closed (C) forms. Our results show that only the opened forms exhibit moderate activity, which, although inferior to the activity exhibited by the archetype metallo-drug cisplatin, is substantially retained in the A2780Cp8 cell line, yielding very low resistance factors. The trend is also maintained on the less cisplatin-sensitive HCT116 line. When the complexes assume the bis-chelated (C) form, the antiproliferative activity is deeply reduced. Two Pt-amine congeners, containing β-alanine and 3-methoxypropylamine, with C and O structures, respectively, were synthesized and their antiproliferative propensity was evaluated for comparison purposes, and a similar scenario was observed. [ABSTRACT FROM AUTHOR]

As reported in our previous papers, a series of quinoxaline-2-carboxamide 1,4-di-N-oxide derivatives were synthesized and studied as anti-tuberculosis agents. Here, the capability of the shake-flask method was studied and the retention time (expressed as log K) of 20 compounds were determined by RP-HPLC analysis. We found that the prediction of log P by the RP-HPLC analysis can result in a high accuracy and can replace the shake-flask method avoiding the experimental problems presented by quinoxaline di-N-oxides. The studied compounds were subjected to the ALOGPS module with the aim of comparing experimental log Po/w values and predicted data. Moreover, a preliminary in silico screening of the QSAR relationship was made confirming the influence of reduction peak potential, lipophilicity, H-bond donor capacity and molecular dimension descriptors on anti-tuberculosis activity. [ABSTRACT FROM AUTHOR]

Abstract: The syntheses, structures and biological evaluation of a series of cisplatin-like complexes containing bis(imidazole) derivatives – the so-called Joseph ligands – are described. Their cytotoxicity is discussed in terms of their polar surface area, rate of aquation, and lipophilicity. The X-ray crystal structure of the platinum diiodido derivative of dimethyl 2-(di(1H-imidazol-2-yl)methyl)malonate) is reported and compared to those of related systems. Molecular modeling studies are focused on the hydrogen bonding properties of such systems, and their relevance to antitumor activity. [Copyright &y& Elsevier]

Abstract: Electrochemical investigation of the interaction between titanocene dichloride and several biomolecules, i.e., human and bovine serum albumin (HSA and BSA), and single-strand and double-strand deoxyribonucleic acid (ss- and ds-DNA) is reported. The addition of biomolecules to a hydroalcoholic solution of TiCp2Cl2 was followed by a decrease in the Ti(IV)/Ti(III) reduction peak current, due to the formation of adducts with lower diffusion coefficients. Qualitative analysis of the data reveals that titanocene dichloride has a higher affinity for proteins than for nucleic acids. [Copyright &y& Elsevier]

Abstract: A study of the electrochemical behavior of a series of antimetastatic mono- and di-ruthenium complexes, namely [Na][trans-RuIIICl4(DMSO)(L)] and [Na]2[{trans-RuIIICl4(DMSO)}2(μ-L)], L=pyrazine (pyz), pyrimidine (pym), 4,4′-bipyridine (bipy), and 1,2-bis-(4-pyridyl)ethylene (etbipy), is reported. The results obtained show that in all dimeric Ru(III) complexes linked by heterocyclic non-chelating N-donor bridges, the two redox centers behave independently (with no remarkable electrochemical interaction), thus conferring no advantage in the likely hypothesis they act as pro-drugs (activation by reduction). Moreover, electrochemical evaluation of interaction between albumin and the title complexes confirms that this protein can act as the vehicle for drugs of this type in blood. [Copyright &y& Elsevier]

Abstract: Cellular uptake of a drug is one of the most important factors influencing its pharmacodynamics and pharmacokinetics. Our laboratory has previously studied platinum uptake following cisplatin, carboplatin and oxaliplatin treatment at sub-lethal doses of selected tumour cell lines. Here we report on the influence of temperature on dose-dependent antiproliferative effects, cellular uptake and DNA platination of these platinum-based drugs tested on MCF-7 human mammary carcinoma cell line. Inductively coupled plasma-mass spectrometry (ICP-MS) technique has been chosen to perform Pt determinations on cells treated with drug concentrations similar with those usually found in vivo in human plasma. The high sensitivity and analytical rapidity of this technique made possible to carry out a very large amount of Pt determinations (about 300) necessary for this study. Hyperthermia (43°C) proved a synergistic effect with cisplatin on cell growth inhibition, while only an additive effect was demonstrated for carboplatin and oxaliplatin. This behaviour might be explained by the higher DNA platination ratio between data at 43 and 37°C of cisplatin with respect to those of carboplatin and oxaliplatin. [Copyright &y& Elsevier]

Abstract: Folates and folate-like molecules represent a class of vectors for drug targeting and delivery. The folate receptor (FR) is overexpressed in many human cancers, therefore folate-cytotoxic drug conjugates can deliver therapeutic agents specifically to FR positive tumours. We have linked, directly through one of the carboxylate functionalities of the folic acid (α or γ), two different chelating arms for a cytotoxic platinum moiety, namely a diamine and a dicarboxylate. Five different derivatives were synthesised by multi-step procedures, purified and characterised; unfortunately, they resulted barely soluble in water, thereby precluding any biochemical and biological tests. [Copyright &y& Elsevier]

Abstract: The growing number of studies on platinum(II) complexes is stimulated by their importance as antitumour chemotherapeutics. 195Pt NMR spectroscopy is a very useful tool for characterizing and investigating these complexes. An accurate estimation of NMR chemical shifts plays an important role in the evaluation of molecular structure. Moreover, the predictions should be fast and accurate in order to be useful as a tool for structure evaluation within a large set of compounds. In this context, ab initio calculations are time consuming and quite difficult because of the relativistic effect that must be considered for the third row transition metals. A new approach is offered here by chemometrics: by means of an artificial neural network algorithm, it is now possible to build a model to predict the chemical shift of a Pt-complex on the basis of its molecular features, thus providing a useful alternative to computational methods. We have successfully applied such a model to 185 different 195Pt chemical shift values. [Copyright &y& Elsevier]

Starting from ethynylestradiol (1), or, more precisely, from its 3,17β-bis-(triethylsilyloxy) derivative 2, two new ligands containing the ethylenediamino motif were synthesised by a Mannich aminomethylation, namely N-methyl-N-(prop-2-ynyl-3-(17α-estradiolyl))-N′,N′-dimethylethylenediamine (3) and N-(prop-2-ynyl-3-(17α-estradiolyl))-N′-methylpiperazine (4). The corresponding platinum(II)-malonato complexes (7 and 8) were prepared through the PtI2 intermediates (namely 5 and 6) by Dhara’s method. The structures of the two platinum complexes were energy-minimised by molecular mechanics employing the Amber force field. Both ligands were joined to the [99mTc(CO)3Cl] moiety, 99mTc being the chief γ-emitter employed in nuclear medicine. Unfortunately, piperazine ligand 4 afforded complexes that were unstable under physiological conditions. The RBA values for both ligands and complexes derived from 3, measured for the two forms of estrogen receptor, were less than 1%. Such a poor degree of ligand recognition may be due to the partial protonation of the amino groups at physiological pH, making the carrier quite hydrophilic, therefore unsuitable for entering the hydrophobic pocket of estrogen receptors. [Copyright &y& Elsevier]

Cisplatin is widely employed as a first-line chemotherapeutic agent for many solid tumors, including malignant pleural mesothelioma (MPM). However, its clinical use is limited by heavy side effects and acquired resistance, the latter being mainly related to enhanced DNA repair. Many clinical trials using combinations of platinum drugs and PARP-1 inhibitors (PARPis) have been carried out, with the hope that such combinations might lead to improved therapeutic efficacy against tumors. Here, the synthesis and efficacy in reducing MPM cell viability of four cisplatin-based Pt(IV) prodrugs containing the PARPi 3-aminobenzamide (3-ABA) fragment are described. The most promising conjugate is more effective than cisplatin or cisplatin/3-ABA combination, administered in equimolar doses, in inhibiting PARP-1 activity and inducing apoptosis in BRCA1/2 wild type MPM cells, grown as monolayer or as multicellular spheroids. [ABSTRACT FROM AUTHOR]

Platinum (Pt)(II) square planar complexes are well-known anticancer drugs whose Mechanism of Action (MOA) are finely tuned by the polar, hydrophobic and aromatic features of the ligands. In the attempt to translate this tunability to the identification of potential neurodrugs, herein, four Pt(II) complexes were investigated in their ability to modulate the self-aggregation processes of two amyloidogenic models: Sup35p7–13 and NPM1264–277 peptides. In particular, phenanthriplatin revealed the most efficient agent in the modulation of amyloid aggregation: through several biophysical assays, as Thioflavin T (ThT), electrospray ionization mass spectrometry (ESI-MS) and ultraviolet-visible (UV-vis) absorption spectroscopy, this complex revealed able to markedly suppress aggregation and to disassemble small soluble aggregates. This effect was due to a direct coordination of phenanthriplatin to the amyloid, with the loss of several ligands and different stoichiometries, by the formation of π–π and π–cation interactions as indicated from molecular dynamic simulations. Presented data support a growing and recent approach concerning the repurposing of metallodrugs as potential novel neurotherapeutics. [ABSTRACT FROM AUTHOR]

Multilayer fluorescent nonporous silica nanoparticles (SNPs) with an external shell containing primary amino groups were used as delivery systems for Pt(IV) candidate antitumor prodrugs. Spherical SNPs of three different sizes (diameter around 120, 100, and 50 nm) were loaded with two different complexes, namely ( OC -6-33)-diamminebis(4-carboxybutanoato)dichloridoplatinum(IV) ( 1 ) and ( OC -6-44)-diammine(4-carboxybutanoato)dichloridoethanolatoplatinum(IV) ( 2 ), through the formation of amide bonds between the pendant amino groups on SNPs and the free carboxylic groups of the complexes. Complex 1 proved to cause heavy and irreversible agglomeration of SNPs; likely, the presence of two reactive carboxylic functionalities induces the formation of cross-links between the amino-decorated SNPs. On the contrary, the conjugates 2 -SNP, obtained from the monofunctionalized 2 , afforded aqueous nano-suspensions reasonably stable toward aggregation. These solutions showed a limited Pt release in water in the absence of any reducing agents, mainly in form of a Pt(IV) derivative generated by the hydrolysis of the Si–O–Si bond of the functionalized arms attached to silica. In the presence of ascorbic acid, the reduction Pt(IV) → Pt(II) caused the release of the active metabolite cisplatin. Conjugates 2 -SNP exhibited much better antiproliferative activity on the Pt-sensitive ovarian A2780 cell line than parent cisplatin and free 2 , due to their more efficient cellular uptake. [ABSTRACT FROM AUTHOR]

The kinetics of solvolysis in pure dimethyl sulfoxide (DMSO) and water/DMSO or water/dimethylformamide (DMF) mixtures of a series of variously N-methylated ethylenediamine (en*) derivatives, cis-[PtCl2(en*)], were studied by using an electrochemical biosensor consisting of DNA immobilized on the surface of screen-printed electrodes, by conductivity measurements, and by multinuclear NMR spectroscopy and ESI-MS techniques. The pattern of the kinetics was found to have significant differences between solvents, especially between the strongly coordinating DMSO and the weakly coordinating DMF co-solvent, employed to increase the solubility of the complexes under study. In particular, cisplatin and cis-[PtCl2(en*)] show rapid solvolysis in the former but significantly slower in the latter, which indicates that the affinity of the Pt core for the S-donor atoms of DMSO overcomes the effect of its steric hindrance. In order to probe these reactions in more detail, density functional theory (DFT) calculations of activation barriers to solvolysis by both pure DMSO and H2O were performed. [ABSTRACT FROM AUTHOR]

Abstract: Mesothelioma is a rare form of cancer that affects the membranous lining of the chest (pleura) and, less commonly, the lining of the abdomen and heart. The disease carries a poor prognosis and is typically associated with exposure to asbestos, a mineral that has been widely used due to its fire resistance and insulating properties. The standard non-surgical treatment for malignant pleural mesothelioma (MPM) is polychemotherapy combining cisplatin/carboplatin and a second agent with a different mechanism of action. This review outlines the use of clinically approved platinum-drugs and the design of metal-drug candidates for the treatment of MPM. [Copyright &y& Elsevier]

We describe herein a novel Pt(iv)–acetamidato complex as a result of the one-pot reaction between cisplatin and the highly reactive peroxyacetimidic acid generated in situ. This is the first example of a Pt(iv) complex containing a N-donor ligand coordinated during the Pt(ii) → Pt(iv) oxidation step. Remarkably, the Pt(iv)-amidato compound is highly soluble and stable in water; it represents an interesting building block for the further development of Pt(iv) antitumor prodrugs. [ABSTRACT FROM AUTHOR]

Platinum(IV) complexes are extensively studied for their activity against cancer cells as potential substitutes for the widely used platinum(II) drugs. PtIV complexes are kinetically inert and need to be reduced to PtII species to play their pharmacological action, thus acting as prodrugs. The mechanism of the reduction step inside the cell is however still largely unknown. Gas‐phase activation of deprotonated platinum(IV) prodrugs was found to generate products in which platinum has a formal +3 oxidation state. IR multiple photon dissociation spectroscopy is thus used to obtain structural information helping to define the nature of both the platinum atom and the ligands. In particular, comparison of calculations at DFT, MP2 and CCSD levels with experimental results demonstrates that the localization of the radical is about equally shared between the dxz orbital of platinum and the pz of nitrogen on the amino group, the latter acting as a non‐innocent ligand. [ABSTRACT FROM AUTHOR]

Platinum(IV) complexes are extensively studied for their activity against cancer cells as potential substitutes for the widely used platinum(II) drugs. PtIV complexes are kinetically inert and need to be reduced to PtII species to play their pharmacological action, thus acting as prodrugs. The mechanism of the reduction step inside the cell is however still largely unknown. Gas‐phase activation of deprotonated platinum(IV) prodrugs was found to generate products in which platinum has a formal +3 oxidation state. IR multiple photon dissociation spectroscopy is thus used to obtain structural information helping to define the nature of both the platinum atom and the ligands. In particular, comparison of calculations at DFT, MP2 and CCSD levels with experimental results demonstrates that the localization of the radical is about equally shared between the dxz orbital of platinum and the pz of nitrogen on the amino group, the latter acting as a non‐innocent ligand. [ABSTRACT FROM AUTHOR]

The study of Pt(IV) antitumor prodrugs able to circumvent some drawbacks of the conventional Pt(II) chemotherapeutics is the focus of a lot of attention. This paper reports a thorough study based on experimental methods (reduction kinetics, electrochemistry, tandem mass spectrometry and IR ion spectroscopy) and quantum–mechanical DFT calculations on the reduction mechanism of cisplatin-based Pt(IV) derivatives having two hydroxido (1), one hydroxido and one acetato (2), or two acetato ligands (3) in axial position. The biological reductants glutathione and ascorbic acid were taken into consideration. The presence of a hydroxido ligand resulted to play an important role in the chemical reduction with ascorbic acid, as verified by 15N-NMR kinetic analysis using 15N-enriched complexes. The reactivity trend (1 > 2 > 3) does not reflect the respective reduction peak potentials (1 < 2 < 3), an inverse relationship already documented in similar systems. Turning to a simplified environment, the Pt(IV) complexes associated with a single reductant molecule (corresponding to the encounter complex occurring along the reaction coordinate in bimolecular reactions in solution) were characterized by IR ion spectroscopy and sampled for their reactivity under collision-induced dissociation (CID) conditions. The complexes display a comparable reduction reactivity ordering as that observed in solution. DFT calculations of the free energy pathways for the observed fragmentation reactions provide theoretical support for the CID patterns and the mechanistic hypotheses on the reduction process are corroborated by the observed reaction paths. The bulk of these data offers a clue of the intricate pathways occurring in solution. Graphic abstract [ABSTRACT FROM AUTHOR]

Copolymers of styrene (STY) and methylmetacrylate (MMA) are widely employed due to the low price of the starting monomers coupled with their synthetic versatility. A chromatographic method was developed for the simultaneous determination of the conversion degree of the single components of the polymer during the copolymerization reaction and the composition of the produced copolymer. The crude reaction mixture is directly analyzed during the reaction with only a dilution pretreatment. Accordingly, the method allows quick and simple monitoring of the reaction as it proceeds. [ABSTRACT FROM AUTHOR]

Cisplatin and several non-steroidal anti-inflammatory drugs (NSAIDs) have been proven to act synergistically or at least additively on several tumor cell lines. Dual-action cisplatin-based Pt(IV) combos containing ketoprofen and naproxen offer good antiproliferative performance on a panel of human tumor cell lines, including a malignant pleural mesothelioma (MPM) one, a very chemoresistant tumor. The main reason of the increased activity relies on the enhanced lipophilicity of these Pt(IV) conjugates that in turn promotes increased cellular accumulation. A quick Pt(IV)→Pt(II) reduction generates the active cisplatin metabolite. The NSAID adjuvant action seems to be almost independent from cyclooxygenase-2 (COX-2) expression in the tumor cells under investigation (lung A-549, colon HT-29, HCT 116, SW480, ovarian A2780, and biphasic MPM MSTO-211H), but it seems to rely (at least in part) on the activation of the NSAID activated gene, NAG-1 (a member of the transforming growth factor beta, TGF-β, superfamily), which has been suggested to be involved in NSAID antiproliferative activity. [ABSTRACT FROM AUTHOR]

Kinetically inert platinum(IV) complexes are receiving growing attention as promising candidates in the effort to develop safe and valid alternatives to classical square-planar Pt(II) complexes currently used in antineoplastic therapy. Their antiproliferative activity requires intracellular Pt(IV)–Pt(II) reduction (activation by reduction). In the present work, a set of five Pt(IV) complexes has been assayed using mass spectrometry–based techniques, i.e., collision-induced dissociation (CID), and IR multiple photon dissociation (IRMPD) spectroscopy, together with ab initio theoretical investigations. Breakdown and reduction mechanisms are observed that lead to Pt(II) species. Evidence is found for typically transient Pt(III) intermediates along the dissociation paths of isolated, negatively charged (electron-rich) Pt(IV) prodrug complexes. [ABSTRACT FROM AUTHOR]

Abstract Chagas disease is a neglected chronical parasitosis caused by the parasite Trypanosoma cruzi (T. cruzi). Nine ferrocenyl Mannich base derivatives were synthetized and characterized to explore their in vitro activity on three T. cruzi strains of the parasite and their cytotoxicity on Vero cells to calculate the selectivity index (SI). Compound 2 , 1-ferrocenyl-3-(4-(4-(trifluoromethyl)phenyl)piperazin-1-yl)propan-1-one, stood out as the most promising derivative showing a half maximal inhibitory concentration (IC 50) value around 5 μM in both amastigote and trypomastigote forms of T. cruzi and SI values higher than 13, being the best value on the trypomastigote forms of the Arequipa strain (SI = 41.7). Moreover, 2 decreased the number of infected cells and was not genotoxic. Furthermore, its possible mechanism of action was studied through the alteration of the metabolites excreted by the parasite during glucose metabolism, the detection of mitochondrial alterations and the inhibition of superoxide dismutase (SOD). Finally, docking studies were executed to analyze the binding mode of the studied compounds to Fe-SOD enzyme. Graphical abstract Image 1 Highlights • Novel ferrocenyl Mannich base derivatives were synthesized and characterized. • The activity and selectivity of the compounds against Chagas disease were evaluated. • The mechanism of action involves the inhibition of iron superoxide dismutase. [ABSTRACT FROM AUTHOR]

The development of safe and affordable antiparasitic agents effective against neglected tropical diseases is a big challenge of the drug discovery. The drugs currently employed have limitations such as poor efficacy, drug resistance or side effects. Thus, the search for new promising drugs is more and more crucial. Metal complexes and, in particular, organometallic compounds may expand the list of the drug candidates due to the peculiar attributes that the presence of the metal core add to the organic fragment ( e.g. , redox and structural features, ability to interact with DNA or protein targets, etc.). To date, most organometallic compounds tested as anti-neglected tropical diseases are based on similarities or activity of the organic ligands against other diseases or parasites and/or consist in modification of existing drugs combining the features of the metal moiety and the organic ligands. This review focuses on recent studies (2012–2017) on organometallic compounds in treating kinetoplastid-caused diseases such as Human African trypanosomiasis, Chagas disease and leishmaniasis. This field of research, however, still lacks exhaustive studies to identify of parasitic targets and quantitative structure-activity relationships for a rational drug design. [ABSTRACT FROM AUTHOR]

The formation of quadruple-stranded DNA induced by planar metal complexes has particular interest in the development of novel anticancer drugs. This is especially relevant for the inhibition of telomerase, which plays an essential role in cancer cell immortalization and is overexpressed in ca. 85–90% of cancer cells. Moreover, G-quadruplexes also exist in other locations in the human genome, namely oncogene promoter regions, and it has been hypothesized that they play a regulatory role in gene transcription. Herein we report a series of new anthracene-containing terpyridine ligands and the corresponding Cu(II) and Pt(II) complexes, with different linkers between the anthracenyl moiety and the terpyridine chelating unit. The interaction of these ligands and metal complexes with different topologies of DNA was studied by several biophysical techniques. The Pt(II) and Cu(II) complexes tested showed affinity for quadruplex-forming sequences with a good selectivity over duplex DNA. Importantly, the free ligands do not have significant affinity for any of the DNA sequences used, which shows that the presence of the metal is essential for high affinity (and selectivity). This effect is more evident in the case of the Pt(II) complexes. Moreover, the presence of a longer linker between the chelating terpyridine unit and the anthracene moiety enhances the interaction with G-quadruplex-forming sequences. We further evaluated the ability of the Cu(II) complexes to interact with, and stabilize G-quadruplex containing regions in oncogene promoters via a polymerase stop assay. These studies indicated that the metal complexes are able to induce G-quadruplex formation and stop polymerase activity. [ABSTRACT FROM AUTHOR]

The octanol/water partition coefficient, logP, is one of the most important physico-chemical parameters for the development of new metal-based anticancer drugs with improved pharmacokinetic properties. This study addresses an issue with the absence of publicly available models to predict logP of Pt(IV) complexes. Following data collection and subsequent development of models based on 187 complexes from literature, we validate new and previously published models on a new set of 11 Pt(II) and 35 Pt(IV) complexes, which were kept blind during the model development step. The error of the consensus model, 0.65 for Pt(IV) and 0.37 for Pt(II) complexes, indicates its good accuracy of predictions. The lower accuracy for Pt(IV) complexes was attributed to experimental difficulties with logP measurements for some poorly-soluble compounds. This model was developed using general-purpose descriptors such as extended functional groups, molecular fragments and E-state indices. Surprisingly, models based on quantum-chemistry calculations provided lower prediction accuracy. We also found that all the developed models strongly overestimate logP values for the three complexes measured in the presence of DMSO. Considering that DMSO is frequently used as a solvent to store chemicals, its effect should not be overlooked when logP measurements by means of the shake flask method are performed. The final models are freely available at http://ochem.eu/article/76903 . [ABSTRACT FROM AUTHOR]