Thiazolotriazoles As Anti-infectives: Design, Synthesis, Biological Evaluation and In Silico Studies

The rational design of novel thiazolo[2,3-c][1,2,4]triazole derivatives was carried out based on previously identified antitubercular hit molecule H127 for discovering potent compounds showing antimicrobial activity. The designed compounds were screened for their binding efficacies against the antibacterial drug target enoyl-[acyl-carrier-protein] reductase, followed by prediction of drug-likeness and ADME properties. The designed analogues were chemically synthesized, characterized by spectroscopic techniques, followed by evaluation of antimicrobial activity against bacterial and fungal strains, as well as antitubercular activity against M. tuberculosis and M. bovis strains. Among the synthesized compounds, five compounds, 10, 11, 35, 37 and 38, revealed antimicrobial activity, albeit with differential potency against various microbial strains. Compounds 10 and 37 were the most active against S. mutans (MIC: 8 μg/mL), while compounds 11 and 37 showed the highest activity against B. subtillis (MIC: 16 μg/mL), whereas compounds 10, 11 and 37 displayed activities against E. coli (MIC: 16 μg/mL). Meanwhile, compounds 10 and 35 depicted activities against S. typhi (MIC: 16 μg/mL) and compound 10 showed antifungal activity against C. albicans (MIC: 32 μg/mL). The current study has identified two broad-spectrum antibacterial hit compounds (10 and 37). Further structural investigation on these molecules is underway to enhance their potency.

Upcycling of Poly(lactic acid) Waste: A Valuable Strategy to Obtain Ionic Liquids

With the aim to investigate new strategies for upcycling of plastic waste, we performed aminolysis of poly(lactic acid) (PLA), using N,N-dimethylethylenediamine (DMEDA), N,N-dimethylpropylenediamine (DMPDA), and 3-aminopropylimidazole (API) as nucleophiles. The N-substituted lactamides obtained were alkylated by using alkyl halides differing in alkyl chain length, obtaining organic salts that in most cases behaved as ionic liquids (ILs). Both aminolysis of PLA and alkylation of amides were carried out taking into consideration the basic principles of the holistic approach to green chemistry, applied at a laboratory scale, and carefully selecting the nature of the reaction solvent, temperature range, and amount of reagents. Organic salts obtained from the alkylation of N-substituted lactamides were investigated to determine their glass or solid-liquid transitions and their thermal stability. Furthermore, cytotoxicity toward normal lung fibroblasts was also assessed. Data collected show that the proposed strategy represents a valuable protocol to upcycle plastic waste, using it as starting material to obtain alternative solvents of potential industrial relevance.

Insights about the ability of folate based supramolecular gels to act as targeted therapeutic agents

With the aim to obtain targeted chemotherapeutic agents, imidazolium and ammonium-based folate salts were synthesized. Their photophysical behavior was investigated both in buffer and buffer/DMSO solution as well as in solid phase, performing UV-vis and fluorescence investigations. Properties of the aggregates were also analyzed by dynamic light scattering. Gelation ability of the salts was analyzed in biocompatible solvents, and gel phases obtained were characterized by determining critical gelation concentrations and gel-solution transition temperatures. Insights about gelator interactions in the tridimensional network were also gained performing ATR-FTIR investigation. Properties of soft materials were further analyzed performing rheology measurements, scanning electron microscopy, fluorescence and resonance light scattering investigations. Antiproliferative activity of organic salts was tested towards two breast cancer cell lines, expressing different levels of folate receptor, namely MDA-MB-231 and MCF-7, and a normal epithelial cell line, like h-TER T-RPE-1, by using MTT assay. Dichlodihydrofluorescein acetate test was performed to verify the role of oxidative stress in cell death. Finally, antiproliferative activity was also evaluated in gel phase, to verify if salts were able to retain biological activity also after the entrapment in the gelatinous network. Results collected evidence that folate based organic salts were able to behave as targeted chemotherapeutic agents both in solution and gel phase, showing uptake mechanism and selectivity indexes that depend on both cancer cell line nature and salt structure.

Exploring the anticancer activity and the mechanism of action of pyrrolomycins F obtained by microwave-assisted total synthesis

Pyrrolomycins (PMs) are a family of naturally occurring antibiotic agents, isolated from the fermentation broth of Actinosporangium and Streptomyces species. Pursuing our studies on pyrrolomycins, we performed the total synthesis of the F-series pyrrolomycins (1-4) by microwave-assisted synthesis (MAOS), thus obtaining the title compounds in excellent yields (63-69%). Considering that there is no evidence so far of the anticancer effect of this class of compounds, we investigated PMs for their antiproliferative activity against HCT116 and MCF-7 cancer cell lines. PMs showed anticancer activity at submicromolar level with a minimal effect on normal epithelial cell line (hTERT RPE-1), and they were able to induce several morphological changes including elongated cells, cytoplasm vacuolization, long and thin filopodia as well as the appearance of tunneling nanotubes (TNTs). These data suggest that PMs could act by impairing the cell membranes and the cytoskeleton organization, with subsequent increase of ROS generation and the activation of different forms of non-apoptotic cell death.

A Benzimidazolium-Based Organic Cage with Antimicrobial Activity

Considering the wide interest in (benz)imidazolium-based drugs, we here report our study on a benzimidazolium-based organic cage as potential antimicrobial and antifungal agent. Cytotoxicity studies on a human derived cell line, SH-SY5Y, showed that the cage is not cytotoxic at all at the investigated concentrations. Anion binding studies demonstrated that the cage can bind anions (chloride and nitrate, in particular) both in organic solvent and 20%v D2O/CD3CN mixture. The cage was also tested as anionophore, showing a weak but measurable transport of chloride and nitrate across LUVs vesicles. Nonetheless, the compounds have antimicrobial activity towards Staphylococcus aureus (Gram-positive bacteria). This is probably the first organic cage studied as anionophore and antimicrobial agent.

Structure-antitumor activity relationships of tripodal imidazolium-amino acid based salts. Effect of the nature of the amino acid, amide substitution and anion

The antitumor activity of imidazolium salts is highly dependent upon their lipophilicity that can be tuned by the introduction of different hydrophobic substituents on the nitrogen atoms of the imidazolium ring of the molecule. Taking this into consideration, we have synthesized and characterized a series of tripodal imidazolium salts derived from L-valine and L-phenylalanine containing different hydrophobic groups and tested them against four cancer cell lines at physiological and acidic pH. At acidic pH (6.2) the anticancer activity of some of the tripodal compounds changes dramatically, and this parameter is crucial to control their cytotoxicity and selectivity. Moreover, several of these compounds displayed selectivity against the control healthy cell line higher than four. The transmembrane anion transport studies revealed moderate transport abilities suggesting that the observed biological activity is likely not the result of just their transport activity. The observed trends in biological activity at acidic pH agree well with the results for the CF leakage assay. These results strongly suggest that this class of compounds can serve as potential chemotherapeutic agents.

Pyrazole[3,4-d]pyrimidine derivatives loaded into halloysite as potential CDK inhibitors

Uncontrolled cell proliferation is a hallmark of cancer as a result of rapid and deregulated progression through the cell cycle. The inhibition of cyclin-dependent kinases (CDKs) activities is a promising therapeutic strategy to block cell cycle of tumor cells. In this work we reported a new example of nanocomposites based on halloysite nanotubes (HNTs)/pyrazolo[3,4-d]pyrimidine derivatives (Si306 and Si113) as anticancer agents and CDK inhibitors. HNTs/Si306 and HNTs/Si113 nanocomposites were synthesized and characterized. The release kinetics were also investigated. Antitumoral activity was evaluated on three cancer cell lines (HeLa, MDA-MB-231 and HCT116) and the effects on cell cycle arrest in HCT116 cells were evaluated. Finally, molecular dynamics simulations were performed of the complexes between Si113 or Si306 and the active site of both CDK 1 and 2.

Naphthalimide Imidazolium-Based Supramolecular Hydrogels as Bioimaging and Theranostic Soft Materials

1,8-Naphthalimide-based imidazolium salts differing for the alkyl chain length and the nature of the anion were synthesized and characterized to obtain fluorescent probes for bioimaging applications. First, their self-assembly behavior and gelling ability were investigated in water and water/dimethyl sulfoxide binary mixtures. Only salts having longer alkyl chains were able to give supramolecular hydrogels, whose properties were investigated by using a combined approach of fluorescence, resonance light scattering, and rheology measurements. Morphological information was obtained by scanning electron microscopy. In addition, conductive properties of organic salts in solution and gel state were analyzed. Imidazolium salts were successfully tested for their possible application as bioimaging and cytotoxic agents toward three cancer cell lines and a nontumoral epithelial cell line. Characterization of their behavior was performed by MTT and cell-based assays. Finally, the biological activity of hydrogels was also investigated. Collectively, our findings showed that naphthalimide-based imidazolium salts are promising theranostic agents and they were able to preserve their biological properties also in the gel phase.

New Synthetic Nitro-Pyrrolomycins as Promising Antibacterial and Anticancer Agents

Pyrrolomycins (PMs) are polyhalogenated antibiotics known as powerful biologically active compounds, yet featuring high cytotoxicity. The present study reports the antibacterial and antitumoral properties of new chemically synthesized PMs, where the three positions of the pyrrolic nucleus were replaced by nitro groups, aiming to reduce their cytotoxicity while maintaining or even enhancing the biological activity. Indeed, the presence of the nitro substituent in diverse positions of the pyrrole determined an improvement of the minimal bactericidal concentration (MBC) against Gram-positive (i.e., Staphylococcus aureus) or -negative (i.e., Pseudomonas aeruginosa) pathogen strains as compared to the natural PM-C. Moreover, some new nitro-PMs were as active as or more than PM-C in inhibiting the proliferation of colon (HCT116) and breast (MCF 7) cancer cell lines and were less toxic towards normal epithelial (hTERT RPE-1) cells. Altogether, our findings contribute to increase the knowledge of the mode of action of these promising molecules and provide a basis for their rationale chemical or biological manipulation.

The Role of Matrix Metalloproteinases (MMP-2 and MMP-9) in Ageing and Longevity: Focus on Sicilian Long-Living Individuals (LLIs)

Extracellular matrix metalloproteinases (MMPs) are a group of proteins that activate substrates by enzymatic cleavage and, on the basis of their activities, have been demonstrated to play a role in ageing. Thus, in order to gain insight into the pathophysiology of ageing and to identify new markers of longevity, we analysed the activity levels of MMP-2 and MMP-9 in association with some relevant haematochemical parameters in a Sicilian population, including long-living individuals (LLIs, ≥95 years old). A cohort of 154 healthy subjects (72 men and 82 women) of different ages (age range 20-112) was recruited. The cohort was divided into five subgroups: the first group with subjects less than 40 years old, the second group ranging from 40 to 64 years old, the third group ranging from 65 to 89 years old, the fourth group ranging from 90 to 94 years old, and the fifth group with subjects more than 95 years old. A relationship was observed between LLIs and MMP-2, but not between LLIs and MMP-9. However, in the LLI group, MMP-2 and MMP-9 values were significantly correlated. Furthermore, in LLIs, we found a positive correlation of MMP-2 with the antioxidant catabolite uric acid and a negative correlation with the inflammatory marker C-reactive protein. Finally, in LLIs MMP-9 values correlated directly both with cholesterol and with low-density lipoproteins. On the whole, our data suggest that the observed increase of MMP-2 in LLIs might play a positive role in the attainment of longevity. This is the first study that shows that serum activity of MMP-2 is increased in LLIs as compared to younger subjects. As far as we are concerned, it is difficult to make wide-ranging conclusions/assumptions based on these observations in view of the relatively small sample size of LLIs. However, this is an important starting point. Larger-scale future studies will be required to clarify these findings including the link with other systemic inflammatory and antioxidant markers.

The gelatinase MMP-9like is involved in regulation of LPS inflammatory response in Ciona robusta

Matrix metalloproteinases (MMPs) are a family of endopeptidases collectively able to degrade the components of the extracellular matrix (ECM), with important roles in many biological processes, such as embryogenesis, normal tissue remodelling, angiogenesis and wound healing. New views on the function of MMPs reveal that they regulate inflammatory response and therefore might represent an early step in the evolution of the immune system. MMPs can affect the activity of cytokines involved in inflammation including TGF-β and TNF-α. MMPs are widely distributed in all kingdoms of life and have likely evolved from a single-domain protein which underwent successive rounds of duplications. In this study, we focused on the Ciona robusta (formerly known as Ciona intestinalis) MMP gelatinase homologue. Gene organization, phylogenetic analysis and 3D modeling supported the closest correlation of C. robusta gelatinase with the human MMP-9. Real-time PCR analysis and zymographic assay showed a prompt expression induced by LPS inoculation and an upregulation of enzymatic activity. Furthermore, we showed that before of the well-known increase of TGF-β and TNF-α levels, a MMP-9like boost occurred, suggesting a possible involvement of MMP-9like in regulating inflammatory response in C. robusta.

Copolymers with both soft and rigid cationic rings as highly selective antimicrobials to combat antibiotic resistant microbes and biofilms

A new series of main-chain copolymers constructed by linkage of both soft and rigid cationic rings demonstrate good biocompatibility, high antimicrobial efficacy and lower propensity to develop resistance against a broad range of microbes.

The crystal structure of 9-butoxy-2-(hydroxymethyl)-2H-imidazo[1,5-a]quinolin-10-ium bromide, C17H21O2N2Br

C17H21O2N2Br, orthorhombic, Pbcn (no. 36), a = 20.179(12) Å, b = 10.902(7) Å, c = 15.026(9) Å, V = 3306(3) Å3, Z = 8, R gt(F) = 0.0465, wR ref(F 2) = 0.1276, T = 296(2) K.

Dicationic ionic liquids as new feeding deterrents

Abstract

In this study, new quaternary bis(ammonium) salts with alkyl-1,X-bis(dimethyldecylammonium) cation and saccharinate, acesulfamate, lactate and pyroglutamate anions were synthesized and characterized by ¹H and ¹³C NMR spectroscopy. Thermal gravimetric and differential scanning calorimetry analyses confirmed that all salts were thermally stable and the majority of them exhibited melting points below 100 °C. The physicochemical properties (viscosity, density, refractive index values, and solubility) of the obtained salts were determined for three compounds with lactate anions. All the tested salts have suitable properties which, in practical application, will reduce the losses caused by the most important storage insects. Most of the synthesized ionic liquids had comparable or better deterrent activity than azadirachtin—an alkaloid known as the most active antifeedant.

Graphical abstract

Electronic supplementary material

The online version of this article (10.1007/s11696-018-0495-6) contains supplementary material, which is available to authorized users.

Synthesis and antibacterial activity of iron-hexacyanocobaltate nanoparticles

This paper deals with the synthesis and characterization of iron-hexacyanocobaltate (FeHCC) and its antibacterial properties. The nanoparticles were prepared by a facile co-precipitation technique. Crystal structure, particle morphology, and elemental composition were determined using X-ray Powder Diffraction, X-ray fluorescence spectroscopy, Transmission Electron Microscopy (TEM), and Infrared Spectroscopy (IR). The antibacterial activity of the FeHCC nanoparticles was tested against Escherichia coli and Staphylococcus aureus as models for Gram-negative and Gram-positive bacteria, respectively, by bacterial counting method and microscopic visualization (TEM, FEG-SEM, and fluorescence microscopy). The results showed that the FeHCC nanoparticles bind to the bacterial cells, inhibit bacterial growth in a dose- and time-dependent manner, inducing a loss of the membrane potential, the production of reactive oxygen species and the release of macromolecules (nucleic acids and proteins) in the extracellular environment. To the best of our knowledge, this is the first study reporting the antimicrobial effects of metal-hexacyanometallates suggesting practical uses of these materials in different areas, such as self-cleaning surfaces or food packaging.

Ionic liquids gels: Soft materials for environmental remediation

HYPOTHESIS

Nanostructured sorbents and, in particular, supramolecular gels are emerging as efficient materials for the removal of toxic contaminants from water, like industrial dyes. It is also known that ionic liquids can dissolve significant amounts of dyes. Consequently, supramolecular ionic liquids gels could be highly efficient sorbents for dyes removal. This would also contribute to overcome the drawbacks associated with dye removal by liquid-liquid extraction with neat ionic liquids which would require large volumes of extractant and a more difficult separation of the phases.

EXPERIMENTS

Herein we employed novel supramolecular ionic liquid gels based on diimidazolium salts bearing naturally occurring or biomass derived anions, to adsorb cationic and anionic dyes from wastewaters. We also carried out a detailed investigation of thermal, structural, morphological and rheological features of our gels to identify which of them are key in designing better sorbents for environmental remediation.

FINDINGS

The most effective gels showed fast and thorough removal of cationic dyes like Rhodamine B. These gels could also be reused up to 20 times without any loss in removal efficiency. Overall, our ionic gels outperform most of gel-based sorbents systems so far reported in literature.

Anticancer activity of biogenerated silver nanoparticles: an integrated proteomic investigation

Silver nanoparticles (AgNPs), embedded into a specific polysaccharide (EPS), were biogenerated by Klebsiella oxytoca DSM 29614 under aerobic (AgNPs-EPS^aer) and anaerobic conditions (AgNPs-EPS^anaer). Both AgNPs-EPS matrices were tested by MTT assay for cytotoxic activity against human breast (SKBR3 and 8701-BC) and colon (HT-29, HCT 116 and Caco-2) cancer cell lines, revealing AgNPs-EPS^aer as the most active, in terms of IC50, with a more pronounced efficacy against breast cancer cell lines. Therefore, colony forming capability, morphological changes, generation of reactive oxygen species (ROS), induction of apoptosis and autophagy, inhibition of migratory and invasive capabilities and proteomic changes were investigated using SKBR3 breast cancer cells with the aim to elucidate AgNPs-EPS^aer mode of action. In particular, AgNPs-EPS^aer induced a significant decrease of cell motility and MMP-2 and MMP-9 activity and a significant increase of ROS generation, which, in turn, supported cell death mainly through autophagy and in a minor extend through apoptosis. Consistently, TEM micrographs and the determination of total silver in subcellular fractions indicated that the Ag⁺ accumulated preferentially in mitochondria and in smaller concentrations in nucleus, where interact with DNA. Interestingly, these evidences were confirmed by a differential proteomic analysis that highlighted important pathways involved in AgNPs-EPS^aer toxicity, including endoplasmic reticulum stress, oxidative stress and mitochondrial impairment triggering cell death trough apoptosis and/or autophagy activation.