Identification of 2-thioxoimidazolidin-4-one derivatives as novel noncovalent proteasome and immunoproteasome inhibitors.

This paper describes the design, synthesis, and biological evaluation of 2-thioxoimidazolidin-4-one derivatives as inhibitors of proteasome and immunoproteasome, potential targets for the treatment of hematological malignancies. In particular, we focused our efforts on the design of noncovalent inhibitors, which might be a promising therapeutic option potentially devoid of drawbacks and side-effects related to irreversible inhibition. Among all the synthesized compounds, we identified a panel of active inhibitors with Ki values towards one or two chymotrypsin-like activities of proteasome (ß5c) and immunoproteasome (ß5i and ß1i subunits) in the low micromolar range. Docking studies suggested a unique binding mode of the molecules in the catalytic site of immunoproteasome proteolytic subunits.

Malignant Mixed Müllerian Tumour of the Uterus: Analysis of 44 Cases.

OBJECTIVES: The aim of our study was to evaluate the clinicopathological features and prognostic factors of uterine carcinosarcoma. PATIENTS AND METHODS: In this retrospective study, the clinical characteristics of 44 patients with uterine MMMT were evaluated. Survival curves were estimated by the Kaplan-Meier method and compared by the log-rank test. RESULTS: Forty-four patients with uterine carcinosarcoma were referred to our unit between 1995 and 2015. Their median age was 66.5 years. All women underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. Twenty-five percent had omental resection. Pelvic lymphadenectomy was performed in 18.2% of the cases. Twenty-six of the patients presented with stage I/II disease, 17 with advanced stages. In 20.5% of the cases there were metastases at diagnosis. Forty women received adjuvant chemotherapy, with complete remission in 67.9% of the cases. Recurrences were observed in 27.3% of the women. Disease-free and overall survival was 27 and 103 months, respectively. The FIGO stage, histological type, tumour size, chemotherapy regimen, pelvic lymphadenectomy, and myometrial invasion did not affect survival. CONCLUSIONS: Uterine MMMT is an aggressive tumour, often diagnosed at an advanced stage and with a high rate of metastases or recurrences. Because of its rarity, its management is controversial and fixed prognostic factors cannot be defined.

Development of novel N-3-bromoisoxazolin-5-yl substituted 2,3-benzodiazepines as noncompetitive AMPAR antagonists.

In this work, we designed and synthesized novel N-3-bromoisoxazolin-5-yl substituted 2,3-benzodiazepines as noncompetitive AMPAR antagonists, with the aim that this heterocycle could establish favourable interactions with a putative binding pocket of the receptor, like the thiadiazole nucleus of GYKI 47409 does. Within this investigation, we identified some active molecules and, among these 2,3-benzodiazepines, 4c showed a much improved inhibitory potency as compared with unsubstituted 2,3-benzodiazepines.

Development of novel 1,4-benzodiazepine-based Michael acceptors as antitrypanosomal agents.

Novel 1,4-benzodiazepines, endowed with a Michael acceptor moiety, were designed taking advantage of a computational prediction of their pharmacokinetic parameters. Among all the synthesized derivatives, we identified a new lead compound (i.e., 4a), bearing a vinyl ketone warhead and endowed with a promising antitrypanosomal activity against Trypanosoma brucei brucei (IC50=5.29µM), coupled with a lack of cytotoxicity towards mammalian cells (TC50 >100µM).

Synthesis and biological evaluation of novel peptidomimetics as rhodesain inhibitors.

Novel rhodesain inhibitors were developed by combining an enantiomerically pure 3-bromoisoxazoline warhead with a 1,4-benzodiazepine scaffold as specific recognition moiety. All compounds were proven to inhibit rhodesain with Ki values in the low-micromolar range. Their activity towards rhodesain was found to be coupled to an in vitro antitrypanosomal activity, with IC50 values ranging from the mid-micromolar to a low-micromolar value for the most active rhodesain inhibitor (R,S,S)-3. All compounds showed a good selectivity against the target enzyme since all of them were proven to be poor inhibitors of human cathepsin L.

Development of novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation.

Novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation were developed; some of them possess K(i) values in the micromolar range. We studied the structure-activity relationship of these derivatives and we performed docking studies, which allowed us to find out the key interactions established by the inhibitors with the target enzyme. Biological results indicate that the nature of the P2 and P3 substituents and their binding to the S2/S3 pockets is strictly interdependent.

Peptide-based proteasome inhibitors in anticancer drug design.

The identification of the key role of the eukaryotic 26S proteasome in regulated intracellular proteolysis and its importance as a target in many pathological conditions wherein the proteasomal activity is defective (e.g., malignancies, autoimmune diseases, neurodegenerative diseases, etc.) prompted several research groups to the development of specific inhibitors of this multicatalytic complex with the aim of obtaining valid drug candidates. In regard to the anticancer therapy, the peptide boronate bortezomib (Velcade®) represents the first molecule approved by FDA for the treatment of multiple myeloma in 2003 and mantle cell lymphoma in 2006. Since then, a plethora of molecules targeting the proteasome have been identified as potential anticancer agents and a few of them reached clinical trials or are already in the market (i.e., carfilzomib; Kyprolis®). In most cases, the design of new proteasome inhibitors (PIs) takes into account a proven peptide or pseudopeptide motif as a base structure and places other chemical entities throughout the peptide skeleton in such a way to create an efficacious network of interactions within the catalytic sites. The purpose of this review is to provide an in-depth look at the current state of the research in the field of peptide-based PIs, specifically those ones that might find an application as anticancer agents.

Mechanism of inhibition of GluA2 AMPA receptor channel opening by 2,3-benzodiazepine derivatives: functional consequences of replacing a 7,8-methylenedioxy with a 7,8-ethylenedioxy moiety.

2,3-Benzodiazepine (2,3-BDZ) compounds are a group of AMPA receptor inhibitors and are drug candidates for treating neurological diseases involving excessive AMPA receptor activity. We investigated the mechanism by which GluA2Q(flip) receptor channel opening is inhibited by two 2,3-BDZ derivatives, i.e., 1-(4-aminophenyl)-3,5-dihydro-7,8-ethylenedioxy-4H-2,3-benzodiazepin-4-one (2,3-BDZ-11-2) and its 1-(4-amino-3-chlorophenyl) analogue (2,3-BDZ-11-4). Both compounds have a 7,8-ethylenedioxy moiety instead of the 7,8-methylenedioxy feature present in the structure of GYKI 52466, the prototypic 2,3-BDZ compound. Using a laser-pulse photolysis approach with a time resolution of ~60 µs and a rapid solution flow technique, we characterized the effect of the two compounds on the channel opening process of the homomeric GluA2Q(flip) receptor. We found that both 2,3-BDZ-11-2 and 2,3-BDZ-11-4 are noncompetitive inhibitors with specificity for the closed-channel conformation of the GluA2Q(flip) receptor. However, 2,3-BDZ-11-4 is ~10-fold stronger, defined by its inhibition constant for the closed-channel conformation (i.e., K(I) = 2 µM), than 2,3-BDZ-11-2. From double-inhibitor experiments, we determined that both compounds bind to the same site, but this site is different from two other known, noncompetitive binding sites on the GluA2Q(flip) receptor previously reported. Our results provide both mechanistic clues to improve our understanding of AMPA receptor regulation and a structure-activity relationship for designing more potent 2,3-BDZ compounds with predictable properties for this new noncompetitive site.

Clinical characteristics and predictors of death among hospitalized patients infected with SARS-CoV-2 in Sicily, Italy: A retrospective observational study.

Since late December 2019, severe acute respiratory syndrome coronavirus 2 has spread across the world, which resulted in the World Health Organization declaring a global pandemic. Coronavirus disease 2019 (COVID-19) presents a highly variable spectrum with regard to the severity of illness. Most infected individuals exhibit a mild to moderate illness (81%); however, 14% have a serious disease and 5% develop severe acute respiratory distress syndrome (ARDS), requiring intensive care support. The mortality rate of COVID-19 continues to rise across the world. Data regarding predictors of mortality in patients with COVID 19 are still scarce but are being actively investigated. The present multicenter retrospective observational study provides a complete description of the demographic and clinical characteristics, comorbidities and laboratory abnormalities in a population of 421 hospitalized patients recruited across eight infectious disease units in Southern Italy (Sicily) with the aim of identifying the baseline characteristics predisposing COVID-19 patients to critical illness or death. In this study, older age, pre-existing comorbidities and certain changes in laboratory markers (such as neutrophilia, lymphocytopenia and increased C-reactive protein levels) at the time of admission were associated with a higher risk of mortality. Male sex, on the other hand, was not significantly associated with increased risk of mortality. Symptoms such as fatigue, older age, a number of co-pathologies and use of continuous positive airway pressure were the most significant contributors in the estimation of clinical prognosis. Further research is required to better characterize the epidemiological features of COVID-19, to understand the related predictors of death and to develop new effective therapeutic strategies.

Falcipain-2 inhibitors.

Malaria, particularly that one caused by Plasmodium falciparum, remains a serious health problem in Africa, South America, and many parts of Asia where it afflicts about 500 million people and is responsible for the death of more than one million children each year. The main reasons for the persistence of malaria are the emergence of resistance to common antimalarial drugs, inadequate control of mosquito vectors, and the lack of effective vaccines. Therefore, the identification and characterization of new targets for antimalarial chemotherapy are of urgent priority. This review is focused on inhibitors of falcipain-2, a cysteine protease from P. falciparum, which represents one of the most promising targets for antimalarial drug design. Falcipain-2 is a key enzyme in the life cycle of P. falciparum since it degrades hemoglobin, at the early trophozoite stage, and cleaves ankyrin and protein 4.1, the cytoskeletal elements vital to the stability of red cell membrane, at the schizont stage. The main classes of falcipain-2 inhibitors are peptides or peptidomimetics bearing the most popular pharmacophores of cysteine protease inhibitors, such as vinyl sulfones, halomethyl ketones, and aldehydes. Furthermore, many other chemotypes have been identified as inhibitors of falcipain-2, such as isoquinolines, thiosemicarbazones, and chalcones. These inhibitors represent all classes, which, to the best of our knowledge, have been disclosed in journal articles to date.

Constrained peptidomimetics as antiplasmodial falcipain-2 inhibitors.

Herein we report the synthesis of a series of novel constrained peptidomimetics 2-10 endowed with a dipeptide backbone (D-Ser-Gly) and a vinyl ester warhead, structurally related to a previously identified lead compound 1, an irreversible inhibitor of falcipain-2, the main haemoglobinase of lethal malaria parasite Plasmodium falciparum. The new compounds were evaluated for their inhibition against falcipain-2, as well as against cultured P. falciparum. The inhibitory activity of the synthesized compounds was also evaluated against another protozoal cysteine protease, namely rhodesain of Trypanosoma brucei rhodesiense.

Novel 2H-isoquinolin-3-ones as antiplasmodial falcipain-2 inhibitors.

A series of 1-aryl-6,7-disubstituted-2H-isoquinolin-3-ones (2-10) was synthesized and evaluated for their inhibition against Plasmodium falciparum cysteine protease falcipain-2, as well as against cultured P. falciparum strain FCBR parasites. All compounds displayed inhibitory activity against recombinant falcipain-2 and against in vitro cultured intraerythrocytic P. falciparum, with the exception of 9. The new compounds exhibited no selectivity against human cysteine proteases such as cathepsins B and L. The inhibitory activity of the synthesized compounds was also evaluated against another protozoal cysteine protease, namely rhodesain of Trypanosoma brucei rhodesiense.

Drug combination studies of curcumin and genistein against rhodesain of Trypanosoma brucei rhodesiense.

Curcumin and genistein are two natural products obtained from Curcuma longa L. and soybeans, endowed with many biological properties. Within the last years they were shown to possess also a promising antitrypanosomal activity. In the present paper, we investigated the activity of both curcumin and genistein against rhodesain, the main cysteine protease of Trypanosoma brucei rhodesiense; drug combination studies, according to Chou and Talalay method, allowed us to demonstrate a potent synergistic effect for the combination curcumin-genistein. As a matter of fact, with our experiments we observed that the combination index of curcumin-genistein is < 1 for the reduction from 10 to 90% of rhodesain activity.

Development of Novel Amides as Noncovalent Inhibitors of Immunoproteasomes.

The development of immunoproteasome-selective inhibitors is a promising strategy for treating hematologic malignancies, autoimmune and inflammatory diseases. In this context, we report the design, synthesis, and biological evaluation of a new series of amide derivatives as immunoproteasome inhibitors. Notably, the designed compounds act as noncovalent inhibitors, which might be a promising therapeutic option because of the lack of drawbacks and side effects associated with irreversible inhibition. Among the synthesized compounds, we identified a panel of active inhibitors with Ki values in the low micromolar or sub-micromolar ranges toward the ß5i and/or ß1i subunits of immunoproteasomes. One of the active compounds was shown to be the most potent and selective inhibitor with a Ki value of 21 nm against the single ß1i subunit. Docking studies allowed us to determine the mode of binding of the molecules in the catalytic site of immunoproteasome subunits.

Development of peptidomimetics with a vinyl sulfone warhead as irreversible falcipain-2 inhibitors.

This paper describes the synthesis of a new class of peptidomimetic cysteine protease inhibitors based on a 1,4-benzodiazepine scaffold and on an electrophilic vinyl sulfone moiety. The former was introduced internally to a peptide sequence that mimics the fragment D-Ser-Gly; the latter was built on the P1-P1' site and reacts as a classical "Michael acceptor", leading to an alkylated enzyme by irreversible addition of the thiol group of the active site cysteine. The introduction of the vinyl sulfone moiety has been accomplished by olefin cross-metathesis, a powerful tool for the formation of carbon-carbon double bonds. New compounds 2-3 have been proven to be potent and selective inhibitors of falcipain-2, a cysteine protease isolated from Plasmodium falciparum, displaying antiplasmodial activity.

Structure-activity study of 2,3-benzodiazepin-4-ones noncompetitive AMPAR antagonists: identification of the 1-(4-amino-3-methylphenyl)-3,5-dihydro-7,8-ethylenedioxy-4H-2,3-benzodiazepin-4-one as neuroprotective agent.

In the search for AMPA receptor (AMPAR) antagonists, 2,3-benzodiazepines represent a family of specific noncompetitive antagonists with anticonvulsant and neuroprotective properties. We have previously shown that 2,3-benzodiazepin-4-ones possess marked anticonvulsant properties and high affinity for the noncompetitive binding site of the AMPAR complex. In this paper, we report the synthesis and pharmacological characterization of a full set of 2,3-benzodiazepin-4-ones in order to better define the structure-activity relationship (SAR) of this class of compounds. Binding assays and functional tests were performed to evaluate the antagonistic activity at the AMPARs. Through these results we have identified a potent AMPAR antagonist, 1-(4-amino-3-methylphenyl)-3,5-dihydro-7,8-ethylenedioxy-4H-2,3-benzodiazepin-4-one (5c). This compound noncompetitively inhibited AMPAR-mediated toxicity in primary mouse hippocampal cultures with an IC(50) of 1.6muM and blocked kainate-induced calcium influx in rat cerebellar granule cells with an IC(50) of 6.4muM. Thus, 5c has the in vitro potential as therapeutic drug in the treatment of various neurological disorders.

Immunoproteasome-selective and non-selective inhibitors: A promising approach for the treatment of multiple myeloma.

The ubiquitin-proteasome system (UPS) is the major non-lysosomal proteolytic system for the degradation of abnormal or damaged proteins no longer required. The proteasome is involved in degradation of numerous proteins which regulate the cell cycle, indicating a role in controlling cell proliferation and maintaining cell survival. Defects in the UPS can lead to anarchic cell proliferation and to tumor development. For these reasons UPS inhibition has become a significant new strategy for drug development in cancer treatment. In addition to the constitutive proteasome, which is expressed in all cells and tissues, higher organisms such as vertebrates possess two immune-type proteasomes, the thymoproteasome and the immunoproteasome. The thymoproteasome is specifically expressed by thymic cortical epithelial cells and has a role in positive selection of CD8+ T cells, whereas the immunoproteasome is predominantly expressed in monocytes and lymphocytes and is responsible for the generation of antigenic peptides for cell-mediated immunity. Recent studies demonstrated that the immunoproteasome has a preservative role during oxidative stress and is up-regulated in a number of pathological disorders including cancer, inflammatory and autoimmune diseases. As a consequence, immunoproteasome-selective inhibitors are currently the focus of anticancer drug design. At present, the commercially available proteasome inhibitors bortezomib and carfilzomib which have been validated in multiple myeloma and other model systems, appear to target both the constitutive and immunoproteasomes, indiscriminately. This lack of specificity may, in part, explain some of the side effects of these agents, such as peripheral neuropathy and gastrointestinal effects, which may be due to targeting of the constitutive proteasome in these tissues. In contrast, by selectively inhibiting the immunoproteasome, it may be possible to maintain the antimyeloma and antilymphoma efficacy while reducing these toxicities, thereby increasing the therapeutic index. This review article will be focused on the discussion of the most promising immunoproteasome specific inhibitors which have been developed in recent years. Particular attention will be devoted to the description of their mechanism of action, their structure-activity relationship, and their potential application in therapy.

Development of Novel Peptide-Based Michael Acceptors Targeting Rhodesain and Falcipain-2 for the Treatment of Neglected Tropical Diseases (NTDs).

This paper describes the development of a class of peptide-based inhibitors as novel antitrypanosomal and antimalarial agents. The inhibitors are based on a characteristic peptide sequence for the inhibition of the cysteine proteases rhodesain of Trypanosoma brucei rhodesiense and falcipain-2 of Plasmodium falciparum. We exploited the reactivity of novel unsaturated electrophilic functions such as vinyl-sulfones, -ketones, -esters, and -nitriles. The Michael acceptors inhibited both rhodesain and falcipain-2, at nanomolar and micromolar levels, respectively. In particular, the vinyl ketone 3b has emerged as a potent rhodesain inhibitor (k2nd = 67 × 106 M-1 min-1), endowed with a picomolar binding affinity (Ki = 38 pM), coupled with a single-digit micromolar activity against Trypanosoma brucei brucei (EC50 = 2.97 µM), thus being considered as a novel lead compound for the discovery of novel effective antitrypanosomal agents.

Synthesis, chiral resolution, and enantiopharmacology of a potent 2,3-benzodiazepine derivative as noncompetitive AMPA receptor antagonist.

This paper describes the synthesis of racemic 3,5-dihydro-5-methyl-7,8-methylenedioxy-4H-2,3-benzodiazepin-4-one (+/-)-5, attempted stereoselective synthesis of its enantiomers, chiral HPLC resolution of the racemate, and assignment of the absolute configuration. Enantiomer (5S)-(-)-5 is provided with an in vivo anticonvulsant activity 8 times higher than its enantiomer (5R)-(+)-5. This result is confirmed in the in vitro test by the ability to inhibit the kainate-induced increase of the [Ca(2+)](i) in a primary culture of rat cerebellar granule cells which express alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. Binding affinity of compound (+/-)-5 at the AMPA and N-methyl-d-aspartic acid (NMDA) receptors was also evaluated.

Novel peptidomimetic cysteine protease inhibitors as potential antimalarial agents.

The synthesis of a new class of peptidomimetics 1a-j, based on a 1,4-benzodiazepine scaffold and on a C-terminal aspartyl aldehyde building block, is described. Compounds 1a-j provided significant inhibitory activity against falcipains 2A and 2B (FP-2A and FP-2B), two cysteine proteases from Plasmodium falciparum.