Silver and Gold Complexes with NHC-Ligands Derived from Caffeine: Catalytic and Pharmacological Activity.

N-heterocyclic carbene (NHC) silver(I) and gold(I) complexes have found different applications in various research fields, as in medicinal chemistry for their antiproliferative, anticancer, and antibacterial activity, and in chemistry as innovative and effective catalysts. The possibility of modulating the physicochemical properties, by acting on their ligands and substituents, makes them versatile tools for the development of novel metal-based compounds, mostly as anticancer compounds. As it is known, chemotherapy is commonly adopted for the clinical treatment of different cancers, even though its efficacy is hampered by several factors. Thus, the development of more effective and less toxic drugs is still an urgent need. Herein, we reported the synthesis and characterization of new silver(I) and gold(I) complexes stabilized by caffeine-derived NHC ligands, together with their biological and catalytic activities. Our data highlight the interesting properties of this series as effective catalysts in A3-coupling and hydroamination reactions and as promising anticancer, anti-inflammatory, and antioxidant agents. The ability of these complexes in regulating different pathological aspects, and often co-promoting causes, of cancer makes them ideal leads to be further structurally functionalized and investigated.

Development of 1-(2-aminophenyl)pyrrole-based amides acting as human topoisomerase I inhibitors.

Topoisomerases are ubiquitous enzymes in the human body, particularly involved in cancer development and progression. Topoisomerase I (topoI) performs DNA relaxation reactions by "controlled rotation" rather than by "strand passage." The inhibition of topoI has become a useful strategy to control cancer cell proliferation. Nowadays, different compounds have undergone clinical trials, but the search for new molecular entities is necessary and benefits from medicinal chemistry efforts. Pyrrole-based compounds emerged as promising antiproliferative agents, with particular interest in breast cancer therapy and topoI inhibition. Starting from these observations and based on the scaffold-hopping approach, we developed a small library of 1-(2-aminophenyl)pyrrole-based amides (7a-f) as new anticancer agents. Tested on a panel of cancer cell lines, 7a-f displayed the most interesting profile in MDA-MB-231 cells, where the most active compounds, 7d-f, were able to induce death by apoptosis. Direct enzymatic assays and docking simulations on the topoI active site (PDB: 1A35) revealed the inhibitory activity and potential binding site for the newly developed 1-(2-aminophenyl)pyrrole-based amides.

Targeting Breast Cancer: An Overlook on Current Strategies.

Breast cancer (BC) is one of the most widely diagnosed cancers and a leading cause of cancer death among women worldwide. Globally, BC is the second most frequent cancer and first most frequent gynecological one, affecting women with a relatively low case-mortality rate. Surgery, radiotherapy, and chemotherapy are the main treatments for BC, even though the latter are often not aways successful because of the common side effects and the damage caused to healthy tissues and organs. Aggressive and metastatic BCs are difficult to treat, thus new studies are needed in order to find new therapies and strategies for managing these diseases. In this review, we intend to give an overview of studies in this field, presenting the data from the literature concerning the classification of BCs and the drugs used in therapy for the treatment of BCs, along with drugs in clinical studies.

Metal Complexes with Schiff Bases: Data Collection and Recent Studies on Biological Activities.

Metal complexes play a crucial role in pharmaceutical sciences owing to their wide and significant activities. Schiff bases (SBs) are multifaceted pharmacophores capable of forming chelating complexes with various metals in different oxidation states. Complexes with SBs are extensively studied for their numerous advantages, including low cost and simple synthetic strategies. They have been reported to possess a variety of biological activities, including antimicrobial, anticancer, antioxidant, antimalarial, analgesic, antiviral, antipyretic, and antidiabetic ones. This review summarizes the most recent studies on the antimicrobial and antiproliferative activities of SBs-metal complexes. Moreover, recent studies regarding mononuclear and binuclear complexes with SBs are described, including antioxidant, antidiabetic, antimalarial, antileishmanial, anti-Alzheimer, and catecholase activities.

Multidrug Resistance (MDR): A Widespread Phenomenon in Pharmacological Therapies.

Multidrug resistance is a leading concern in public health. It describes a complex phenotype whose predominant feature is resistance to a wide range of structurally unrelated cytotoxic compounds, many of which are anticancer agents. Multidrug resistance may be also related to antimicrobial drugs, and is known to be one of the most serious global public health threats of this century. Indeed, this phenomenon has increased both mortality and morbidity as a consequence of treatment failures and its incidence in healthcare costs. The large amounts of antibiotics used in human therapies, as well as for farm animals and even for fishes in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. It is not negligible that the ongoing COVID-19 pandemic may further contribute to antimicrobial resistance. In this paper, multidrug resistance and antimicrobial resistance are underlined, focusing on the therapeutic options to overcome these obstacles in drug treatments. Lastly, some recent studies on nanodrug delivery systems have been reviewed since they may represent a significant approach for overcoming resistance.

Drugs for COVID-19: An Update.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the seventh known human coronavirus, and it was identified in Wuhan, Hubei province, China, in 2020. It caused the highly contagious disease called coronavirus disease 2019 (COVID-19), declared a global pandemic by the World Health Organization (WHO) on 11 March 2020. A great number of studies in the search of new therapies and vaccines have been carried out in these three long years, producing a series of successes; however, the need for more effective vaccines, therapies and other solutions is still being pursued. This review represents a tracking shot of the current pharmacological therapies used for the treatment of COVID-19.

A Phenylacetamide Resveratrol Derivative Exerts Inhibitory Effects on Breast Cancer Cell Growth.

Resveratrol (RSV) is a natural compound that displays several pharmacological properties, including anti-cancer actions. However, its clinical application is limited because of its low solubility and bioavailability. Here, the antiproliferative and anti-inflammatory activity of a series of phenylacetamide RSV derivatives has been evaluated in several cancer cell lines. These derivatives contain a monosubstituted aromatic ring that could mimic the RSV phenolic nucleus and a longer flexible chain that could confer a better stability and bioavailability than RSV. Using MTT assay, we demonstrated that most derivatives exerted antiproliferative effects in almost all of the cancer cell lines tested. Among them, derivative 2, that showed greater bioavailability than RSV, was the most active, particularly against estrogen receptor positive (ER+) MCF7 and estrogen receptor negative (ER-) MDA-MB231 breast cancer cell lines. Moreover, we demonstrated that these derivatives, particularly derivative 2, were able to inhibit NO and ROS synthesis and PGE2 secretion in lipopolysaccharide (LPS)-activated U937 human monocytic cells (derived from a histiocytoma). In order to define the molecular mechanisms underlying the antiproliferative effects of derivative 2, we found that it determined cell cycle arrest at the G1 phase, modified the expression of cell cycle regulatory proteins, and ultimately triggered apoptotic cell death in both breast cancer cell lines. Taken together, these results highlight the studied RSV derivatives, particularly derivative 2, as promising tools for the development of new and more bioavailable derivatives useful in the treatment of breast cancer.

The Different Facets of Triclocarban: A Review.

In the late 1930s and early 1940s, it was discovered that the substitution on aromatic rings of hydrogen atoms with chlorine yielded a novel chemistry of antimicrobials. However, within a few years, many of these compounds and formulations showed adverse effects, including human toxicity, ecotoxicity, and unwanted environmental persistence and bioaccumulation, quickly leading to regulatory bans and phase-outs. Among these, the triclocarban, a polychlorinated aromatic antimicrobial agent, was employed as a major ingredient of toys, clothing, food packaging materials, food industry floors, medical supplies, and especially of personal care products, such as soaps, toothpaste, and shampoo. Triclocarban has been widely used for over 50 years, but only recently some concerns were raised about its endocrine disruptive properties. In September 2016, the U.S. Food and Drug Administration banned its use in over-the-counter hand and body washes because of its toxicity. The withdrawal of triclocarban has prompted the efforts to search for new antimicrobial compounds and several analogues of triclocarban have also been studied. In this review, an examination of different facets of triclocarban and its analogues will be analyzed.

From coins to cancer therapy: Gold, silver and copper complexes targeting human topoisomerases.

Cancer is a complex issue and, even though the prevention basics and therapy have been implemented, it is still the second leading death cause worldwide. With the hope to discover new powerful and safer molecules to fight cancer, many researchers focused their attention on metal-based compounds, starting from the most famous and successfully employed anticancer drug, i.e. cisplatin. The current article aims to report the most recent discoveries about the use of gold, silver and copper complexes as antitumor agents, highlighting their influences on important enzymes, namely human topoisomerases. The latter are fundamental for the cell life and, if overexpressed, strongly implicated in cancer onset and progression. The identification of lead complexes targeting human topoisomerases and gifted with the appropriate chemical and pharmacological properties represents a fecund starting point to obtain new and more effective anticancer molecules.

Synthesis, anticancer and antioxidant properties of new indole and pyranoindole derivatives.

The indole scaffold has been recognized, over the years, as a model for the synthesis of compounds with anticancer activity by dint of its substantiated ability to act via multiple mechanisms, which also involves the inhibition of enzymes engaged in DNA replication. In this regard, a new series of indole and pyranoindole derivatives have been prepared, some of which showed good antitumor activity and proved their inhibitory effects on the tubulin target. The anticancer activity of the newly synthesized compounds has been evaluated on breast cancer cell lines, as MCF-7 and MDA-MB231, cervical cancer cells line HeLa and Ishikawa endometrial cancer cell line. Among the compounds under study, 7 exhibited a good antitumor activity on HeLa cell line (IC50 = 3.6 ± 0.5), leading to cell death by apoptosis due to the inhibition of tubulin polymerization, which demonstrated that the compound can explicate its function in a similar way to Vinblastine, a well-known inhibitor of tubulin polymerization. The data were also confirmed by in silico assays. No cytotoxicity against normal cells has been detected. Furthermore, in order to investigate the antioxidant properties, DPPH and ABTS tests were performed, together with fluorescence assays on 3T3-L1 cells. All our findings taken together led us to consider compound 7 a favourable candidate for the battle against cancer.

Newly Synthesized Imino-Derivatives Analogues of Resveratrol Exert Inhibitory Effects in Breast Tumor Cells.

Breast cancer represents the most frequently diagnosed malignancy in women worldwide. Various therapeutics are currently used in order to halt the progression of breast tumor, even though certain side effects may limit the beneficial effects. In recent years, many efforts have been addressed to the usefulness of natural compounds as anticancer agents due to their low toxicity. Resveratrol, a stilbene found in grapes, berries, peanuts and soybeans, has raised a notable interest for its antioxidant, anti-inflammatory, and antitumor properties. Here, we report the design, the synthesis and the characterization of the anticancer activity of a small series of imino N-aryl-substituted compounds that are analogues of resveratrol. In particular, the most active compound, named 3, exhibited anti-tumor activity in diverse types of breast cancer cells through the inhibition of the human topoisomerase II and the induction of apoptotic cell death. Therefore, the abovementioned compound maybe considered as a promising agent in more comprehensive treatments of breast cancer.

Carbazole Derivatives as Antiviral Agents: An Overview.

Keywords: carbazole; tetrahydrocarbazole; antiviral agents.

N-thioalkylcarbazoles derivatives as new anti-proliferative agents: synthesis, characterisation and molecular mechanism evaluation.

Synthetic or natural carbazole derivatives constitute an interesting class of heterocycles, which showed several pharmaceutical properties and occupied a promising place as antitumour tools in preclinical studies. They target several cellular key-points, e.g. DNA and Topoisomerases I and II. The most studied representative, i.e. Ellipticine, was introduced in the treatment of metastatic breast cancer. However, because of the onset of dramatic side effects, its use was almost dismissed. Many efforts were made in order to design and synthesise new carbazole derivatives with good activity and reduced side effects. The major goal of the present study was to synthesise a series of new N-thioalkylcarbazole derivatives with anti-proliferative effects. Two compounds, 5a and 5c, possess an interesting anti-proliferative activity against breast and uterine cancer cell lines without affecting non-tumoural cell lines viability. The most active compound (5c) induces cancer cells death triggering the intrinsic apoptotic pathway by inhibition of Topoisomerase II.

Chloro-1,4-dimethyl-9H-carbazole Derivatives Displaying Anti-HIV Activity.

BACKGROUND: Despite the progress achieved by anti-retroviral drug research in the last decades, the discovery of novel compounds endowed with selective antiviral activity and reduced side effects is still a necessity. At present, the most urgent requirement includes the improvement of HIV (Human Immunodeficiency Virus) prevention and sexual transmission and the development of new drugs to treat the chronic lifelong infection. METHODS: Six chloro-1,4-dimethyl-9H-carbazoles (2a,b-4a,b) have been prepared following opportunely modified known chemical procedures and tested in luciferase and Escherichia coli ß-galactosidase expressing CD4⁺, CXCR4⁺, CCR5⁺ TZM-bl cells. RESULTS AND CONCLUSION: a preliminary biological investigation on the synthesized small series of chloro-1,4-dimethyl-9H-carbazoles has been carried out. Among all tested compounds, a nitro-derivative (3b) showed the most interesting profile representing a suitable lead for the development of novel anti-HIV drugs.

Synthesis and Antitumor Activity of New Group 3 Metallocene Complexes.

The quest for alternative drugs with respect to the well-known cis-platin and its derivatives, which are still used in more than 50% of the treatment regimens for patients suffering from cancer, is highly needed. In this context, organometallic compounds, which are defined as metal complexes containing at least one direct covalent metal-carbon bond, have recently been found to be promising anticancer drug candidates. A series of new metallocene complexes with scandium, yttrium, and neodymium have been prepared and characterized. Some of these compounds show a very interesting anti-proliferative activity in triple negative breast cancer cell line (MDA.MB231) and the non-hormone sensitive prostate cancer cell line (DU145). Moreover, the interaction of some of them with biological membranes, evaluated using liposomes as bio-membrane mimetic model systems, seems to be relevant. The biological activity of these compounds, particularly those based on yttrium, already effective at low concentrations on both cancer cell lines, should be taken into account with regard to new therapeutic approaches in anticancer therapy.

Anti-Inflammatory, Antioxidant and Crystallographic Studies of N-Palmitoyl-ethanol Amine (PEA) Derivatives.

N-Palmitoyl-ethanolamine (PEA) is an anti-inflammatory component of egg yolk that is usually employed for the prevention of respiratory apparatus virus infection and then frequently used for its efficient anti-inflammatory and analgesic effects in experimental models of visceral, neuropathic, and inflammatory diseases. Nevertheless, data of its use in animal or human therapy are still scarce and further studies are needed. Herein, we report the biological evaluation of a small library of N-palmitoyl-ethanolamine analogues or derivatives, characterized by a protected acid function (either as palmitoyl amides or hexadecyl esters), useful to decrease their hydrolysis rate in vitro and prolong their biological activity. Two of these compounds-namely phenyl-carbamic acid hexadecyl ester (4) and 2-methyl-pentadecanoic acid (4-nitro-phenyl)-amide (5)-have shown good anti-inflammatory and antioxidant properties, without affecting the viability of J774A.1 macrophages. Finally, crystals suitable for X-ray analysis of compound 4 have been obtained, and its solved crystal structure is here reported. Our outcomes may be helpful for a rational drug design based on new PEA analogues/derivatives with improved biological properties.

Sericin/Poly(ethylcyanoacrylate) Nanospheres by Interfacial Polymerization for Enhanced Bioefficacy of Fenofibrate: In Vitro and In Vivo Studies.

Fenofibrate is a lipophilic drug used in hypercholesterolemia and hypertriglyceridemia as a lipid-regulating agent; however, it is characterized by poor water solubility and low dissolution rate, which result in a low oral bioavailability. In the present study, sericin/poly(ethylcyanoacrylate) nanospheres are synthesized by interfacial polymerization in aqueous media and investigated as a novel sericin-based delivery system for improved and enhanced oral bioefficacy of fenofibrate. The incorporation of sericin into the prepared cyanoacrylate nanoparticles and their spherical shape are confirmed by Lowry assay and scanning electron microscopy, respectively. Hydrophilic and mucoadhesive properties of the synthesized nanospheres are also evaluated. Finally, both in vitro release and in vivo studies are performed and the oral absorbable amount of fenofibrate is calculated to be higher than 70% when incorporated into the polymeric material, reducing the levels of total cholesterol (TC), triacylglycerols (TG), very low-density lipoproteins (VLDL), and low-density lipoproteins (LDL) compared to fenofibrate alone.

Inhibition of human topoisomerase I and II and anti-proliferative effects on MCF-7 cells by new titanocene complexes.

The antitumor activity shown by many platinum complexes has produced a strong interest in research of new organometallic compounds having anticancer action. Among the many metal compounds synthesized and tested, those based on titanium have received considerable attention because of their cytotoxic activity against solid tumors. Particularly, new titanocene compounds containing aromatic groups linked to the Cp (cyclopentadienyl ring, C5H5) have been synthetized, such as the titanocene Y (bis-[(p-methoxybenzyl)cyclopentadienyl]titanium dichloride) that displayed promising medium-high cytotoxic activity on breast cancer cell lines. Other titanocene complexes recently synthesized, obtained by replacing the substituent methoxy-aryl of cyclopentadienes of titanocene Y with ethenyl-methoxide or ethenyl-phenoxide, showed increased cytotoxic activity on breast cancer cell lines being more stable compounds. In this paper, we report that new titanocene complexes holding lipophilic groups, for instance a methyl group on benzyl carbon, exhibit improved antiproliferative effect on breast cancer cell line MCF-7. Similar results have been obtained introducing a 5-methoxy naphthyl group to further stabilize the titanocene complexes. These inhibitory effects on breast cancer cells have been ascribed to human topoisomerase I and II inhibition as demonstrated by specific enzymatic assays.

AR collaborates with ERα in aromatase inhibitor-resistant breast cancer.

Androgen receptor (AR) is an attractive target in breast cancer because of its frequent expression in all the molecular subtypes, especially in estrogen receptor (ER)-positive luminal breast cancers. We have previously shown a role for AR overexpression in tamoxifen resistance. We engineered ER-positive MCF-7 cells to overexpress aromatase and AR (MCF-7 AR Arom cells) to explore the role of AR in aromatase inhibitor (AI) resistance. Androstendione (AD) was used as a substrate for aromatization to estrogen. The nonsteroidal AI anastrazole (Ana) inhibited AD-stimulated growth and ER transcriptional activity in MCF-7 Arom cells, but not in MCF-7 AR Arom cells. Enhanced activation of pIGF-1R and pAKT was found in AR-overexpressing cells, and their inhibitors restored sensitivity to Ana, suggesting that these pathways represent escape survival mechanisms. Sensitivity to Ana was restored with AR antagonists, or the antiestrogen fulvestrant. These results suggest that both AR and ERα must be blocked to restore sensitivity to hormonal therapies in AR-overexpressing ERα-positive breast cancers. AR contributed to ERα transcriptional activity in MCF-7 AR Arom cells, and AR and ERα co-localized in AD + Ana-treated cells, suggesting cooperation between the two receptors. AR-mediated resistance was associated with a failure to block ER transcriptional activity and enhanced up-regulation of AR and ER-responsive gene expression. Clinically, it may be necessary to block both AR and ERα in patients whose tumors express elevated levels of AR. In addition, inhibitors to the AKT/IGF-1R signaling pathways may provide alternative approaches to block escape pathways and restore hormone sensitivity in resistant breast tumors.

N-alkyl carbazole derivatives as new tools for Alzheimer's disease: preliminary studies.

Alzheimer's disease (AD) is a progressive and age-related neurodegenerative disorder affecting brain cells and is the most common form of "dementia", because of the cognitive detriment which takes place. Neuronal disruption represents its major feature, due to the cytosolic accumulation of amyloid ß-peptide (Aß) which leads to senile plaques formation and intracellular neurofibrillary tangles. Many studies have focused on the design and therapeutic use of new molecules able to inhibit Aß aggregation. In this context, we evaluated the ability of two recently synthesized series of N-alkyl carbazole derivatives to increase the Aß soluble forms, through molecular docking simulations and in vitro experiments. Our data evidenced that two carbazole derivatives, the most active, adopt distinct binding modes involving key residues for Aß fibrillization. They exhibit a good interfering activity on Aß aggregation in mouse (N2a) cells, stably expressing wild-type human amyloid precursor protein (APP) 695. These preliminary results are promising and we are confident that the N-alkyl carbazole derivatives may encourage next future studies needed for enlarging the knowledge about the AD disease approach.