Search

β-lactam antibiotics (BLAs) are crucial molecules among antibacterial drugs, but the increasing emergence of resistance to them, developed by bacteria producing β-lactamase enzymes (BLEs), is becoming one of the major warnings to the global public health. Since only a small number of novel antibiotics are in development, a current clinical approach to limit this phenomenon consists of administering proper combinations of β-lactam antibiotics (BLAs) and β-lactamase inhibitors (BLEsIs). Unfortunately, while few clinically approved BLEsIs are capable of inhibiting most class-A and -C serine β-lactamases (SBLEs) and some carbapenemases of class D, they are unable to inhibit most part of the carbapenem hydrolyzing enzymes of class D and the worrying metallo-β-lactamases (MBLEs) of class B. Particularly, MBLEs are a set of enzymes that catalyzes the hydrolysis of a broad range of BLAs by a zinc-mediated mechanism, and currently no clinically available molecule capable of inhibiting MBLEs exists. Additionally, new types of alarming “superbugs”, were found to produce the New Delhi metallo-β-lactamases (NDMs) encoded by increasing variants of a plasmid-mediated gene capable of rapidly spreading among bacteria of the same species and even among different species. Particularly, NDM-1 possesses a flexible hydrolysis mechanism that inactivates all BLAs, except for aztreonam. The present review provides first an overview of existing BLAs and the most clinically relevant BLEs detected so far. Then, the BLEsIs and their most common associations with BLAs already clinically applied and those still in development are reviewed.

The increasing emergence of bacteria producing β-lactamases enzymes (BLEs), able to inactivate the available β-lactam antibiotics (BLAs), causing the hydrolytic opening of their β-lactam ring, is one of the global major warnings. According to Ambler classification, BLEs are grouped in serine-BLEs (SBLEs) of class A, C, and D, and metal-BLEs (MBLEs) of class B. A current strategy to restore no longer functioning BLAs consists of associating them to β-lactamase enzymes inhibitors (BLEsIs), which, interacting with BLEs, prevent them hydrolyzing to the associated antibiotic. Worryingly, the inhibitors that are clinically approved are very few and inhibit only most of class A and C SBLEs, leaving several class D and all MBLEs of class B untouched. Numerous non-clinically approved new molecules are in development, which have shown broad and ultra-broad spectrum of action, some of them also being active on the New Delhi metal-β-lactamase-1 (NDM-1), which can hydrolyze all available BLAs except for aztreonam. To not duplicate the existing review concerning this topic, we have herein examined BLEsIs by a chemistry approach. To this end, we have reviewed both the long-established synthesis adopted to prepare the old BLEsIs, those proposed to achieve the BLEsIs that are newly approved, and those recently reported to prepare the most relevant molecules yet in development, which have shown high potency, providing for each synthesis the related reaction scheme.

Fenretinide (4-HPR), a retinoid derivative, has shown high antitumor activity, a low toxicological profile, and no induction of resistance. Despite these favorable features, the variability in oral absorption due to its low solubility combined with the high hepatic first pass effect strongly reduce clinical outcomes. To overcome the solubility and dissolution challenges of poorly water-soluble 4-HPR, we prepared a solid dispersion of the drug (4-HPR-P5) using a hydrophilic copolymer (P5) previously synthesized by our team as the solubilizing agent. The molecularly dispersed drug was obtained by antisolvent co-precipitation, an easy and up-scalable technique. A higher drug apparent solubility (1134-fold increase) and a markedly faster dissolution were obtained. In water, the colloidal dispersion showed a mean hydrodynamic diameter of 249 nm and positive zeta potential (+41.3 mV), confirming the suitability of the formulation for intravenous administration. The solid nanoparticles were also characterized by a high drug payload (37%), as was also evidenced by a chemometric-assisted Fourier transform infrared spectroscopy (FTIR) investigation. The 4-HPR-P5 exhibited antiproliferative activity, with IC50 values of 1.25 and 1.93 µM on IMR-32 and SH-SY5Y neuroblastoma cells, respectively. Our data confirmed that the 4-HPR-P5 formulation developed herein was able to increase drug apparent aqueous solubility and provide an extended release over time, thus suggesting that it represents an efficient approach to improve 4-HPR bioavailability.

In the treatment of pediatric diseases, mass-produced dosage forms are often not suitable for children. Commercially available medicines are commonly manipulated and mixed with food by caregivers at home, or extemporaneous medications are routinely compounded in the hospital pharmacies to treat hospitalized children. Despite considerable efforts by regulatory agencies, the pediatric population is still exposed to questionable and potentially harmful practices. When designing medicines for children, the ability to fine-tune the dosage while ensuring the safety of the ingredients is of paramount importance. For these purposes solid formulations may represent a valid alternative to liquid formulations for their simpler formula and more stability, and, to overcome the problem of swelling ability, mini-tablets could be a practicable option. This review deals with the different approaches that may be applied to develop mini-tablets intended for pediatrics with a focus on the safety of excipients. Alongside the conventional method of compression, 3D printing appeared particularly appealing, as it allows to reduce the number of ingredients and to avoid both the mixing of powders and intermediate steps such as granulation. Therefore, this technique could be well adaptable to the daily galenic preparations of a hospital pharmacy, thus leading to a reduction of the common practice of off-label preparations.

In the original publication [...]

It is widely reported that N-(4-hydroxyphenyl)-retinamide or fenretinide (4-HPR), which is a synthetic amide of all-trans-retinoic acid (ATRA), inhibits in vitro several types of tumors, including cancer cell lines resistant to ATRA, at 1–10 µM concentrations. Additionally, studies in rats and mice have confirmed the potent anticancer effects of 4-HPR, without evidencing hemolytic toxicity, thus demonstrating its suitability for the development of a new chemo-preventive agent. To this end, the accurate determination of 4-HPR levels in tissues is essential for its pre-clinical training, and for the correct determination of 4-HPR and its metabolites by chromatography, N-(4-ethoxyphenyl)-retinamide (4-EPR) has been suggested as an indispensable internal standard. Unfortunately, only a consultable old patent reports the synthesis of 4-EPR, starting from dangerous and high-cost reagents and using long and tedious purification procedures. To the best of our knowledge, no article existed so far describing the specific synthesis of 4-EPR. Only two vendors worldwide supply 4-ERP, and its characterization was incomplete. Here, a scalable, operator-friendly, and one-step procedure to synthetize highly pure 4-EPR without purification work-up and in quantitative yield is reported. Additionally, a complete characterization of 4-EPR using all possible analytical techniques has been provided.

All-trans-retinoic acid (ATRA) represents the first-choice treatment for several skin diseases, including epithelial skin cancer and acne. However, ATRA’s cutaneous side effects, like redness and peeling, and its high instability limit its efficacy. To address these drawbacks and to improve ATRA solubilization, we prepared ATRA-loaded micelles (ATRA-TPGSs), by its encapsulation in D-α-tocopheryl-polyethylene-glycol-succinate (TPGS). First, to explore the feasibility of the project, a solubility study based on the equilibrium method was performed, then, six ATRA-TPGS formulations were prepared by the solvent-casting method using different TPGS amounts. ATRA-TPGSs showed small sizes (11–20 nm), low polydispersity, slightly negative zeta potential, and proved good encapsulation efficiency, confirmed by a chemometric-assisted Fourier transform infrared spectroscopy (FTIR) investigation. ATRA-TPGS stability was also investigated to choose the most stable formulation. Using Carbopol® 980 as gelling agent, ATRA-TPGS-loaded gels were obtained and analyzed for their rheological profiles. Ex vivo release studies from ATRA-TPGSs were performed by Franz cells, demonstrating a permeation after 24 h of 22 ± 4 µ cm−2. ATRA-TPGSs showed enhanced cytotoxic effects on melanoma cells, suggesting that these formulations may represent a valid alternative to improve patient compliance and to achieve more efficacious therapeutic outcomes.

Even though immunotherapy has radically changed the search for anticancer therapies, there are still many different pathways that are open to intervention with traditional small molecules. To expand our investigation in the anticancer field, we report here a new series of compounds in which our previous pyrazole and imidazopyrazole scaffolds are linked to a differently decorated phenyl ring through an acylhydrazone linker. Preliminary tests on the library were performed at the National Cancer Institute (USA) against the full NCI 60 cell panel. The best compounds among the imidazopyrazole series were then tested by immunofluorescence staining for their inhibition of cell proliferation, apoptosis induction, and their effect on the cell cycle and on microtubules. Two compounds, in particular 4-benzyloxy-3-methoxybenzyliden imidazopyrazole-7-carbohydrazide showed good growth inhibition, with IC50 values in the low-micromolar range, and induced apoptosis. Both compounds altered the cell-cycle phases with the appearance of polyploid cells. Immunofluorescence analysis evidenced microtubules alterations; tubulin polymerization assays and docking studies suggested the tubulin system to be the possible, although not exclusive, target of the new acylhydrazone series reported here.

It is well-known that the health properties attributed to several fruits, herbs, seeds and their processed foods/beverages are due to an important group of natural polyphenols classified as hydrolysable tannins (HT) named ellagitannins (ETs), that encompass both one or more gallic acid (GA) units and one or more hexahydroxydiphenoic acid (HHDP) units, ester-connected with a sugar residue. In vivo, ETs are rather not absorbed and in gastrointestinal tract (GIT), they are hydrolysed providing mainly ellagic acid (EA). Due to its trivial water-solubility, first pass effect, metabolism in GIT, or irreversible binding to cellular DNA and proteins, EA has a very low bioavailability. Some authors are studying methods to increase EA water-solubility and thus to improve its bioavailability. At the same, EA metabolism to urolithins (UROs), whose concentration and activity is inter-individual and intra-individual dependent, is still under study and not completely elucidate. Numerous in vitro and in vivo studies have been carried out to define the molecular and cellular events underlying the beneficial effects that this compound and its metabolites exert in pathological conditions. The anti-inflammatory and the antioxidant properties of EA attracted the interest of researchers for its potential health benefits in humans, including anti-cancer, anti-diabetes activities and cardio-protection. Nevertheless, lately the attention paid to EA is focusing on its potential protective action towards several neurodegenerative disorders. Thus, EA is investigated as a potential “lead compound” endowed with multi-target pharmacological properties on CNS. Since the identification of the pharmacophore(s) responsible for both health benefits and collateral effects of this compound is crucial in drug discovery, this review aims to provide an all-round updated analysis of the literature concerning EA involvement in several CNS disorders, hoping that such information will be useful to researchers involved in multi-target drug design for CNS.

Several anti-inflammatory agents based on pyrazole and imidazopyrazole scaffolds and a large library of substituted catechol PDE4D inhibitors were reported by us in the recent past. To obtain new molecules potentially able to act on different targets involved in inflammation onset we designed and synthesized a series of hybrid compounds by linking pyrazole and imidazo-pyrazole scaffolds to differently decorated catechol moieties through an acylhydrazone chain. Some compounds showed antioxidant activity, inhibiting reactive oxygen species (ROS) elevation in neutrophils, and a good inhibition of phosphodiesterases type 4D and, particularly, type 4B, the isoform most involved in inflammation. In addition, most compounds inhibited ROS production also in platelets, confirming their ability to exert an antiinflammatory response by two independent mechanism. Structure&ndash, activity relationship (SAR) analyses evidenced that both heterocyclic scaffolds (pyrazole and imidazopyrazole) and the substituted catechol moiety were determinant for the pharmacodynamic properties, even if hybrid molecules bearing to the pyrazole series were more active than the imidazopyrazole ones. In addition, the pivotal role of the catechol substituents has been analyzed. In conclusion the hybridization approach gave a new serie of multitarget antiinflammatory compounds, characterized by a strong antioxidant activity in different biological targets.

An unprecedented, highly convergent, high-yielding, one-pot synthesis of (acyl)hydrazones and thiosemicarbazones was carried out by the in situ condensation of isolable iminium chlorides of imidazolidin-2-(thio)one, tetrahydropyrimidin-2-thione and indole derivatives with nitrogen nucleophiles in the presence of a base. The developed reaction procedure is largely advantageous. It is highly parallelizable, no intermediates need to be isolated and minimal sample handling is required during the purification steps. Some relevant reaction parameters including reaction temperature and p $$K_\mathrm{a}$$ of the base are discussed. NMR analysis was carried out to assess the stereochemistry of the obtained compounds. The stereochemical outcome of the reaction was found to be affected by the nature of the nitrogen-containing nucleophile being the majority of the derivatives isolated as single geometric isomers. The cytotoxicity and antiviral activities of the prepared compounds have been preliminary assessed. In cell-based screenings some of the derivatives proved to be cytotoxic at low micromolar concentrations and interesting anti-Reo-1 properties have been detected.

The multistep preparation of the new 10-substituted 2-(1-piperazinyl)pyrimido[1,2- a ]benzimidazol-4(10 H )-ones 6a – o , and of the two isomers 10-ethyl-2-(diethylamino)pyrimido[1,2- a ]benzimidazol-4(10 H )-one 6p and 10-ethyl-4-(diethylamino)pyrimido[1,2- a ]benzimidazol-2(10 H )-one 13 , as well as the in vitro evaluation of their inhibitory activity on human platelet aggregation induced in platelet-rich plasma by ADP, collagen or the Ca 2+ ionophore A23187 were here described. Nine out of fifteen 2-(1-piperazinyl)derivatives ( 6g – o ) showed good inhibitory properties towards all the platelet aggregation agonists used. Moreover, a molecular modelling study has been performed on two of the best compounds of this series ( 6i and 6o ) to confirm in silico their interactions with the catalytic site of human platelet PDE3, using the X-ray data of the PDE3B isoform in complex with an inhibitor.

A surface extract of the aerial parts of Salvia chamaedryoides afforded 13 diterpenes (1-13), with seven compounds (1, 3, 4, 7-9, 12) described for the first time. The structures of the new compounds were established using 1D and 2D NMR spectroscopic methods, HRESIMS, and ECD data. The potential hypoglycemic effects of the crude extract, fractions, and pure compounds from S. chamaedryoides were investigated by inhibition of α-glucosidase and α-amylase enzymes. The extract and its fractions showed a moderate dose-dependent inhibition; the pure compounds exhibited differential inhibitory activity against these two enzymes. Molecular modeling studies were also performed to suggest the interaction mode of compound 3 in the α-glucosidase enzyme active site. The antimicrobial activity of the purified compounds was investigated against 26 clinical pathogens. No activity was detected for the Gram-negative species tested nor on Candida albicans and C. glabrata, while variable susceptibilities were observed using Gram-positive staphylococcal and enterococcal species.

Saccharidic monomers and a macromonomer were synthesized and copolymerized in the presence of divinylbenzene (DVB) as crosslinker in conditions of separation of phases to give hydrophilic nanostructured sugar-based vinyl copolymers. Appropriate model molecules such as N -benzyl- d -gluconamide for the saccharidic copolymers and 4-(4-chlorobutoxy)benzaldehyde and ( E )-4-(4-chloro-2-butenyloxy)benzaldehyde for electrophilic reagents prefiguring possible copper amine oxidase inhibitors allowed identification of conditions for useful monofunctionalizations mainly at the position 2 of the saccharidic units. The examined samples of the nanostructured copolymers from one of the monomers proved to be stable enough to tolerate the functionalization reactions without loss of morphology.

Through the synthesis and study of model systems as proper dithiane derivatives, vinyl monomers and soluble copolymeric reagents containing 2-unsubstituted 1,3-dithiane rings, we attained the key synthon 1,3-dithiane-5-methanol. Through its reaction with commercial resins, new polymeric reagents useful for supported organic synthesis and combinatorial chemistry were developed. Exploiting the reactivity of position 2 in 1,3-dithiane rings, such polymeric reagents were employed in the production of aldehydes from alkyl halides through a process entirely free from unpleasant odors.

A new series of indole-based analogues were recently identified as potential anticancer agents. The Knoevenagel-type indoles herein presented were prepared via a one-pot condensation of iminium salts with active methylene reagents and were isolated as single geometric isomers. Biological evaluation in different cell-based assays revealed an antiproliferative activity for some analogues already in the nanomolar range against leukaemia, breast and renal cancer cell lines. To explain these effects, the most promising analogues of the series were engaged in further cell-based studies. Compounds 5e, l, p and 6a, b highlighted a pro-apoptotic potential being able to induce apoptosis in HL60, K562 and MCF-7 cell lines in a dose and time-dependent manner. The ability of these compounds to arrest cell cycle at the G2/M phase inspired the immunofluorescence studies which allowed us to identify tubulin as a potential target for compounds 5l and 6b.

A new group of 5-(alkylamino)-9-isopropyl[1,2,4]triazolo[4,3- a ][1,8]naphthyridine derivatives bearing a CONHR group at the 6-position ( 1c – g ), designed to obtain new effective analgesic and/or anti-inflammatory agents, were synthesized and tested along with three new 9-alkyl-5-(4-alkyl-1-piperazinyl)- N,N -diethyl [1,2,4]triazolo[4,3- a ][1,8]naphthyridine-6-carboxamides ( 2b – d ). Besides, a new class of analogues of compounds 1 and 2 , bearing a Mannich base moiety at the 9-position ( 12a – d ), as well as the novel N,N -diethyl-5-(isobutylamino)-8-methyl-10-oxo-10 H -pyrimido[1,2- a ][1,8]naphthyridine-6-carboxamide ( 15 ) were prepared and tested. Compounds 1c – g exhibited very interesting anti-inflammatory properties in rats, whereas compounds 2b – d and 15 proved to be endowed with prevalent analgesic activity frequently associated with sedative effects in mice. On the contrary, the Mannich bases 12a – d resulted inactive. The most effective (80% inhibition of oedema) and potent (threshold dose 1.6 mg kg −1 with 31% inhibition of oedema) anti-inflammatory compound 1d did not show gastrolesive effects following 100 mg kg −1 oral administration in rats.

The formation of tetrasubstituted benzenes and doubly lithiated intermediates in metalation/formylation reactions of 3-methoxymethoxyanisole has been observed with the methoxymethoxy group acting as a leaving group in some cases.

In order to obtain substrate-like inhibitors of copper amine oxidases (CAOs), a class of enzymes involved in important cellular processes as well as in crosslinking of elastin and collagen and removal of biogenic primary amines, we synthesized a set of benzylamine derivatives properly substituted at positions 2 and 6 and studied their biological activity towards some members of CAOs. With benzylamines 6, 7, 8 containing linear alkoxy groups we obtained reversible inhibitors of benzylamine oxidase (BAO), very active and selective toward diamine oxidase (DAO), lysyl oxidase (LO) and monoamine oxidase B (MAO B) characterized by a certain toxicity consequent to the crossing of the brain barrier. Poorly toxic, up to very active, reversible inhibitors of BAO, very selective toward DAO, LO and MAO B, were obtained with benzylamines 10, 11, 12 containing hydrophilic ω-hydroxyalkoxy groups. With benzylamines 13, 14, 15, containing linear alkyl groups endowed with steric, but not conjugative effects for the absence of properly positioned oxygen atoms, we synthesized moderately active inhibitors of BAO reversible and selective toward DAO, LO and MAO B. The cross examination of the entire biological data brought us to the conclusion that the bioactive synthesized compounds most likely exert their physiological role of reversible inhibitors in consequence of the formation of a plurality of hydrogen bonds or hydrophobic non-covalent interactions with proper sites in the protein. Accordingly, the reported inhibitors may be considered as a set of research tools for general biological studies and the formation of enzyme complexes useful for X-ray structure determinations aimed at the design of more sophisticated inhibitors to always better modulate the protein activity without important side effects.

A simple one-pot procedure for the stereoselective synthesis of Knoevenagel-type indoles is described. The method is based on the in situ reaction of indole iminium salts (four of them are fully characterized) with acyclic symmetrical and unsymmetrical active methylene reagents in the presence of triethylamine. In general, the overall yields are moderate to good. Some of relevant reaction parameters and steric effects affecting stereoselectivity are discussed.

Sugar-based co-polymers with saccharidic units in stable cyclic form and nanometric morphologies stabilized through crosslinking, adaptable through specific functionalizations to biochemical interaction studies with copper-containing amine oxidases, were synthesized from appropriate monomers and macromonomers. The most promising nanospherical co-polymer obtained, containing β- d -glucopyranosidic units, was employed in functionalization reactions with the help of model molecules, achieving useful transformations mainly at the 6-position and to a minor extent at the 2-position of the saccharidic system.

The first substratelike, reversible inhibitors of different copper amine oxidases (CAOs) with IC50 (M) as low as 2.0 x 10(-8) corresponding to derivatives of 4-aminomethylpyridine with alkoxy (1a-d), alkylthio (2a,b), and alkylamino (3a-e, 4a-j) groups in the positions 3 and 5 have been prepared and studied. The inhibitors 1a-d are active on benzylamine oxidase and semicarbazide-sensitive amine oxidase and are very selective with respect to diamine oxidase, lysyl oxidase, and monoamine oxidases. The inhibitors 2a,b are selective for benzylamine oxidase whereas 2a is also a new type of good substrate of diamine oxidase. The inhibitors 3a-e and 4a-j are substratelike, reversible, nonselective inhibitors of various CAOs including pea seedling amine oxidase and Hansenula polymorpha amine oxidase, whose enzymatic sites are known from X-ray structure determinations. The inhibitors 3b,c and 4b,c are excellent substratelike tools for studies correlating CAOs that afford crystals suitable for X-ray structure determinations with CAOs from mammals.