Direct-Acting Antivirals and Host-Targeting Approaches against Enterovirus B Infections: Recent Advances.

Enterovirus B (EV-B)-related diseases, which can be life threatening in high-risk populations, have been recognized as a serious health problem, but their clinical treatment is largely supportive, and no selective antivirals are available on the market. As their clinical relevance has become more serious, efforts in the field of anti-EV-B inhibitors have greatly increased and many potential antivirals with very high selectivity indexes and promising in vitro activities have been discovered. The scope of this review encompasses recent advances in the discovery of new compounds with anti-viral activity against EV-B, as well as further progress in repurposing drugs to treat these infections. Current progress and future perspectives in drug discovery against EV-Bs are briefly discussed and existing gaps are spotlighted.

Antiviral Mechanisms of N-Phenyl Benzamides on Coxsackie Virus A9.

Enteroviruses are one of the most abundant groups of viruses infecting humans, and yet there are no approved antivirals against them. To find effective antiviral compounds against enterovirus B group viruses, an in-house chemical library was screened. The most effective compounds against Coxsackieviruses B3 (CVB3) and A9 (CVA9) were CL212 and CL213, two N-phenyl benzamides. Both compounds were more effective against CVA9 and CL213 gave a better EC50 value of 1 µM with high a specificity index of 140. Both drugs were most effective when incubated directly with viruses suggesting that they mainly bound to the virions. A real-time uncoating assay showed that the compounds stabilized the virions and radioactive sucrose gradient as well as TEM confirmed that the viruses stayed intact. A docking assay, taking into account larger areas around the 2-and 3-fold axes of CVA9 and CVB3, suggested that the hydrophobic pocket gives the strongest binding to CVA9 but revealed another binding site around the 3-fold axis which could contribute to the binding of the compounds. Together, our data support a direct antiviral mechanism against the virus capsid and suggest that the compounds bind to the hydrophobic pocket and 3-fold axis area resulting in the stabilization of the virion.

Malaria transmission blocking compounds: a patent review.

INTRODUCTION: Despite substantial progress in the field, malaria remains a global health issue and currently available control strategies are not sufficient to achieve eradication. Agents able to prevent transmission are likely to have a strong impact on malaria control and have been prioritized as a primary objective to reduce the number of secondary infections. Therefore, there is an increased interest in finding novel drugs targeting sexual stages of Plasmodium and innovative methods to target malaria transmission from host to vector, and vice versa. AREAS COVERED: This review covers innovative transmission-blocking inventions patented between 2015 and October 2021. The focus is on chemical interventions, which could be used as 'chemical vaccines' to prevent transmission (small molecules, carbohydrates, and polypeptides). EXPERT OPINION: Even though the development of novel strategies to block transmission still requires fundamental additional research and a deeper understanding of parasite sexual stages biology, the research in this field has significantly accelerated. Among innovative inventions patented over the last 6 years, the surface-delivery of antimalarial drugs to kill transmission-stages parasites in mosquitoes holds the highest promise for success in malaria control strategies, opening completely new scenarios in malaria transmission-blocking drug discovery.

Nano-Based Drug Delivery Systems of Potent MmpL3 Inhibitors for Tuberculosis Treatment.

Tuberculosis remains one of the world's deadliest infectious diseases, accounting for nearly 1.3 million deaths every year. Tuberculosis treatment is challenging because of the toxicity, decreased bioavailability at the target site of the conventional drugs and, most importantly, low adherence of patients; this leads to drug resistance. Here, we describe the development of suitable nanocarriers with specific physicochemical properties to efficiently deliver two potent antimycobacterial compounds. We prepared nanoemulsions and niosomes formulations and loaded them with two different MmpL3 inhibitors previously identified (NEs + BM635 and NIs + BM859). NEs + BM635 and NIs + BM859 were deeply characterized for their physicochemical properties and anti-mycobacterial activity. NEs + BM635 and NIs + BM859 showed good hydrodynamic diameter, ζ-Potential, PDI, drug-entrapment efficiency, polarity, and microviscosity and stability. Even though both formulations proved to perform well, only NIs + BM859 showed potent antimycobacterial activity against M. tuberculosis (MIC = 0.6 µM) compared to that of the free compound. This is most probably caused by the fact that BM635, being highly hydrophobic, encounters maximum hindrance in diffusion, whereas BM859, characterized by high solubility in aqueous medium (152 µM), diffuses more easily. The niosomal formulation described in this work may be a useful therapeutic tool for tuberculosis treatment, and further studies will follow to characterize the in vivo behavior of the formulation.

A Novel Class of Dual-Acting DCH-CORMs Counteracts Oxidative Stress-Induced Inflammation in Human Primary Tenocytes.

Carbon monoxide (CO) can prevent cell and tissue damage by restoring redox homeostasis and counteracting inflammation. CO-releasing molecules (CORMs) can release a controlled amount of CO to cells and are emerging as a safer therapeutic alternative to delivery of CO in vivo. Sustained oxidative stress and inflammation can cause chronic pain and disability in tendon-related diseases, whose therapeutic management is still a challenge. In this light, we developed three small subsets of 1,5-diarylpyrrole and pyrazole dicobalt(0)hexacarbonyl (DCH)-CORMs to assess their potential use in musculoskeletal diseases. A myoglobin-based spectrophotometric assay showed that these CORMs act as slow and efficient CO-releasers. Five selected compounds were then tested on human primary-derived tenocytes before and after hydrogen peroxide stimulation to assess their efficacy in restoring cell redox homeostasis and counteracting inflammation in terms of PGE2 secretion. The obtained results showed an improvement in tendon homeostasis and a cytoprotective effect, reflecting their activity as CO-releasers, and a reduction of PGE2 secretion. As these compounds contain structural fragments of COX-2 selective inhibitors, we hypothesized that such a composite mechanism of action results from the combination of CO-release and COX-2 inhibition and that these compounds might have a potential role as dual-acting therapeutic agents in tendon-derived diseases.

6-Fluorophenylbenzohydrazides inhibit Mycobacterium tuberculosis growth through alteration of tryptophan biosynthesis.

A major constraint in reducing tuberculosis epidemic is the emergence of strains resistant to one or more of clinically approved antibiotics, which emphasizes the need of novel drugs with novel targets. Genetic knockout strains of Mycobacterium tuberculosis (Mtb) have established that tryptophan (Trp) biosynthesis is essential for the bacterium to survive in vivo and cause disease in animal models. An anthranilate-like compound, 6-FABA, was previously shown to synergize with the host immune response to Mtb infection in vivo. Herein, we present a class of anthranilate-like compounds endowed with good antimycobacterial activity and low cytotoxicity. We show how replacing the carboxylic moiety with a hydrazide led to a significant improvement in both activity and cytotoxicity relative to the parent compound 6-FABA. Several new benzohydrazides (compounds 20-31, 33, 34, 36, 38 and 39) showed good activities against Mtb (0.625 ≤ MIC≤6.25 µM) and demonstrated no detectable cytotoxicity against Vero cell assay (CC50 ≥ 1360 µM). The target preliminary studies confirmed the hypothesis that this new class of compounds inhibits Trp biosynthesis. Taken together, these findings indicate that fluorophenylbenzohydrazides represent good candidates to be assessed for drug discovery.

Dietary flavonoids: Nano delivery and nanoparticles for cancer therapy.

Application of nanotechnologies to cancer therapy might increase solubility and/or bioavailability of bioactive compounds of natural or synthetic origin and offers other potential benefits in cancer therapy, including selective targeting. In the present review we aim to evaluate in vivo studies on the anticancer activity of nanoparticles (NPs) obtained from food-derived flavonoids. From a systematic search a total of 60 studies were identified. Most of the studies involved the flavanol epigallocatechin-3-O-gallate and the flavonol quercetin, in both delivery and co-delivery (with anti-cancer drugs) systems. Moreover, some studies investigated the effects of other flavonoids, such as anthocyanins aglycones anthocyanidins, flavanones, flavones and isoflavonoids. NPs inhibited tumor growth in both xenograft and chemical-induced animal models of cancerogenesis. Encapsulation improved bioavailability and/or reduced toxicity of both flavonoids and/or co-delivered drugs, such as doxorubicin, docetaxel, paclitaxel, honokiol and vincristine. Moreover, flavonoids have been successfully applied in molecular targeted nanosystems. Selectivity for cancer cells involves pH- and/or reactive oxygen species-mediated mechanisms. Furthermore, flavonoids are good candidates as drug delivery for anticancer drugs in green synthesis systems. In conclusion, although human studies are needed, NPs obtained from food-derived flavonoids have promising anticancer effects in vivo.

Therapeutic potential for coxibs-nitric oxide releasing hybrids in cystic fibrosis.

This review discusses the rational for further studies of COX-2 inhibitors-NO releaser hybrids (NO-Coxibs) in the pharmacological treatment of the airway inflammation in Cystic Fibrosis (CF). Our research group developed several classes of NO-Coxibs for the pharmacological treatment of arthritis, and among them several compounds showed an outstanding in vivo efficacy and good pharmacokinetic properties. The good antiinflammatory properties displayed by these compounds during the previous screening could, by itself, suggest appropriate candidates for further testing in CF.

SAR Analysis of Small Molecules Interfering with Energy-Metabolism in Mycobacterium tuberculosis.

Tuberculosis remains the world's top infectious killer: it caused a total of 1.5 million deaths and 10 million people fell ill with TB in 2018. Thanks to TB diagnosis and treatment, mortality has been falling in recent years, with an estimated 58 million saved lives between 2000 and 2018. However, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains is a major concern that might reverse this progress. Therefore, the development of new drugs acting upon novel mechanisms of action is a high priority in the global health agenda. With the approval of bedaquiline, which targets mycobacterial energy production, and delamanid, which targets cell wall synthesis and energy production, the energy-metabolism in Mtb has received much attention in the last decade as a potential target to investigate and develop new antimycobacterial drugs. In this review, we describe potent anti-mycobacterial agents targeting the energy-metabolism at different steps with a special focus on structure-activity relationship (SAR) studies of the most advanced compound classes.

Novel Pyrazole-Containing Compounds Active against Mycobacterium tuberculosis.

In this study, a series of 49 five-membered heterocyclic compounds containing either a pyridine- or a pyrrole-type nitrogen were synthesized and tested against Mycobacterium tuberculosis. Among them, only the 1,3,5-trisubstituted pyrazoles 5-49 exhibited minimum inhibitory concentration values in the low micromolar range, and some also exhibited an improved physicochemical profile without cytotoxic effects. Three pyrazoles were subjected to an animal tuberculosis efficacy model, and compound 6 induced a statistically significant difference in lung bacterial counts compared with untreated mice. Moreover, to determine the target of this series, resistors were generated, and whole genome sequencing revealed mutations in the mmpL3 gene.

Mycobacterial tryptophan biosynthesis: A promising target for tuberculosis drug development?

The biosynthetic pathways of amino acids are attractive targets for drug development against pathogens with an intracellular behavior like M. tuberculosis (Mtb). Indeed, while in the macrophages Mtb has restricted access to amino acids such as tryptophan (Trp). Auxotrophic Mtb strains, with mutations in the Trp biosynthetic pathway, showed reduced intracellular survival in cultured human and murine macrophages and failed to cause the disease in immunocompetent and immunocompromised mice. Herein we present recent efforts in the discovery of Trp biosynthesis inhibitors.

Chocolate Consumers and Lymphocyte-to-Monocyte Ratio: A Working Hypothesis from a Preliminary Report of a Pilot Study in Celiac Subjects.

BACKGROUND AND AIM: The aim of this work was to evaluate the relationship between platelet-to-lymphocyte ratio (PLR) and lymphocyte-to-monocyte ratio (LMR) with habitual consumption of dark chocolate in a group of celiac subjects in which chocolate consumption and lower neutrophil-to-lymphocyte ratio (NLR) association had already been observed. Additionally, due to the known anti-nutrient effect on iron absorption, we evaluated red blood cell count (RBC), mean corpuscular volume (MCV) and hemoglobin (Hb) values. METHODS: Chocolate consumers and non-consumers were matched for sex, menopausal status, NLR values over the previously suggested cut off (2.32) for celiac patients, and co-morbidities. RESULTS: Chocolate consumers had high LMR compared to non-consumers, whereas no differences were observed between chocolate consumers and non-consumers in RBC, MCV, Hb and PLR. However, similar number of subjects had PLR higher than the previously suggested cut off (143.7) for celiac disease. CONCLUSIONS: This preliminary report suggests a working hypothesis for larger studies aimed at establishing cut off values for LMR in celiac patients and the modulation of this marker by dietary antioxidants.

In vivo potent BM635 analogue with improved drug-like properties.

BM635 is the hit compound of a promising anti-TB compound class. Herein we report systematic variations around the central pyrrole core of BM635 and we describe the design, synthesis, biological evaluation, pharmacokinetic analysis, as well as in vivo TB mouse efficacy studies of novel BM635 analogues that show improved physicochemical properties. This hit-to-lead campaign led to the identification of a new analogue, 4-((1-isopropyl-5-(4-isopropylphenyl)-2-methyl-1H-pyrrol-3-yl)methyl)morpholine (17), that shows excellent activity (MIC = 0.15 µM; SI = 133) against drug-sensitive Mycobacterium tuberculosis strains, as well as efficacy in a murine model of TB infection.

Pharmaceutical salt of BM635 with improved bioavailability.

BM635 is a small molecule endowed with outstanding anti-mycobacterial activity (minimum inhibitory concentration of 0.12µM against M. tuberculosis H37Rv) identified during a hit-to-lead campaign. Its poor aqueous solubility together with its high lipophilicity led to low exposure in vivo. Indeed, the half-life in vivo of BM635 was 1h, allowing a reasonable maximum concentration (Cmax=1.62µM) and a moderate bioavailability (46%). The present study aimed to develop salt forms of BM635 with pharmaceutically accepted hydrochloric, methanesulphonic, phosphoric, tartaric, and citric acids to overcome these drawbacks. BM635 salts (BM635-HCl, BM635-Mes, BM635-PA, BM635-TA and BM635-CA) were evaluated for physicochemical as well as biopharmaceutical attributes.

A Series of COX-2 Inhibitors Endowed with NO-Releasing Properties: Synthesis, Biological Evaluation, and Docking Analysis.

Herein we report the synthesis, biological evaluation, and docking analysis of a class of cyclooxygenase-2 (COX-2) inhibitors with nitric oxide (NO)-releasing properties. In an earlier study, a number of selective COX-2 inhibitors/NO donors were developed by conjugating a diarylpyrrole scaffold endowed with selective COX-2 inhibitory properties with various nitrooxyalkyl side chains such as esters, α-amino esters, amides, α-amino amides, ethers, ß-amino ethers, inverse esters, and amides. These candidates were found to have high in vitro potencies (COX-2 inhibition at 10 µm: ≥96 %), great efficacy in determining NO-vasorelaxing responses, and good antinociceptive activity in an abdominal writhing test. Among the compounds synthesized in the present work, derivative 2 b [2-(2-(1-(3-fluorophenyl)-2-methyl-5-(4-sulfamoylphenyl)-1H-pyrrol-3-yl)acetamido)ethyl nitrate] showed particularly outstanding activity, with efficacy similar to that of celecoxib even at very low concentrations.

MmpL3 Inhibitors: Diverse Chemical Scaffolds Inhibit the Same Target.

MmpL3 belongs to the Resistance, Nodulation and Division (RND) superfamily whose role in mycobacteria is the formation of the outer membrane. Indeed, it has been shown that MmpL3 is associated with the export of mycolic acids in the form of trehalose monomycolates (TMM) to the periplasmic space or the outer membrane. In the last few years several whole cell-based screenings of compound libraries brought by a number of diverse chemical scaffolds active against M. tuberculosis (Mtb) that surprisingly share MmpL3 as target. The diverse identified pharmacophores owe important differences among each other, in fact while some of them display inhibitory activity against pathogens that are devoid of mycolic acids and are active against non-replicating Mtb bacilli, some others specifically target mycobacteria and do not kill non-replicating bacilli. The scope of this review is to provide the recent advances in MmpL3 inhibitor discovery with a special focus on structure activity relationship (SAR) studies in order to provide information that could help in developing novel membrane-active anti- TB agents. Moreover, this review will provide the most recent insights into the modes of action of the MmpL3 inhibitors.

COX inhibitors: a patent review (2011 - 2014).

INTRODUCTION: The COX enzymes play a central role in the biosynthetic pathway of important biological mediators called prostanoids. Differences in regulation of gene expression, stability of transcripts and proteins determine the different biological functions of COX-1 and COX-2. While the COX-1 gene has been considered to be a 'housekeeping' gene expressed in many tissues and cells, COX-2 gene is upregulated during inflammation, hypoxia and in many cancers. AREAS COVERED: The first part of this review provides a survey of the development of both modified traditional NSAIDs (tNSAIDs) and COX inhibitors (coxibs) with reduced side effects for the treatment of inflammation and cancer. The second part deals with patents reporting several dual inhibitors characterized by the conjugation of a COX-inhibitor scaffold to a molecule able to modulate a different target. Finally, two patents on novel COX inhibitor scaffolds are reported. EXPERT OPINION: The most interesting branch of research concerns the conjugation of a COX-inhibitor scaffold to a molecule able to modulate a different target, in order to either enhance anti-inflammatory activity or to act as a dual inhibitor. Among the described compounds, selenium-containing coxibs inhibiting COX-2 and Akt, in addition to the multi-target biphenyl derivatives as dual inhibitors of COX and fatty acid amide hydrolase, are the most promising ones.

Synthesis, biological evaluation and docking analysis of a new series of methylsulfonyl and sulfamoyl acetamides and ethyl acetates as potent COX-2 inhibitors.

We report herein the synthesis, biological evaluation and docking analysis of a new series of methylsulfonyl, sulfamoyl acetamides and ethyl acetates that selectively inhibit cyclooxygenase-2 (COX-2) isoform. Among the newly synthesized compounds, some of them were endowed with a good activity against COX-2 and a good selectivity COX-2/COX-1 in vitro as well as a desirable analgesic activity in vivo, proving that replacement of the ester moiety with an amide group gave access to more stable derivatives, characterized by a good COX-inhibition.

SAR analysis of new anti-TB drugs currently in pre-clinical and clinical development.

Despite enormous efforts have been made in the hunt for new drugs, tuberculosis (TB) still remains the first bacterial cause of mortality worldwide, causing an estimated 8.6 million new cases and 1.3 million deaths in 2012. Multi-drug resistant-TB strains no longer respond to first-line drugs and are inexorably spreading with an estimated 650,000 cases as well as extensively-drug resistant-TB strains, which are resistant to any fluoroquinolone and at least one of the second-line drugs, with 60,000 cases. Thus the discovery and development of new medicines is a major keystone for tuberculosis treatment and control. After decades of dormancy in the field of TB drug development, recent efforts from various groups have generated a promising TB drug pipeline. Several new therapeutic agents are concurrently studied in clinical trials together with much activity in the hittolead and lead optimization stages. In this article we will review the recent advances in TB drug discovery with a special focus on structure activity relationship studies of the most advanced compound classes.