Expanding the knowledge around antitubercular 5-(2-aminothiazol-4-yl)isoxazole-3-carboxamides: Hit-to-lead optimization and release of a novel antitubercular chemotype via scaffold derivatization

Tuberculosis is one of the deadliest infectious diseases in the world, and the increased number of multidrug-resistant and extensively drug-resistant strains is a reason for concern. We have previously reported a series of substituted 5-(2-aminothiazol-4-yl)isoxazole-3-carboxamides with growth inhibitory activity against Mycobacterium tuberculosis strains and low propensity to be substrate of efflux pumps. Encouraged by these preliminary results, we have undertaken a medicinal chemistry campaign to determine the metabolic fate of these compounds and to delineate a reliable body of Structure-Activity Relationships. Keeping intact the (thiazol-4-yl)isoxazole-3-carboxamide core, as it is deemed to be the pharmacophore of the molecule, we have extensively explored the structural modifications able to confer good activity and avoid rapid clearance. Also, a small set of analogues based on isostere manipulation of the 2-aminothiazole were prepared and tested, with the aim to disclose novel antitubercular chemotypes. These studies, combined, were instrumental in designing improved compounds such as 42g and 42l, escaping metabolic degradation by human liver microsomes and, at the same time, maintaining good antitubercular activity against both drug-susceptible and drug-resistant strains.

Identification of Human Alanine-Glyoxylate Aminotransferase Ligands as Pharmacological Chaperones for Variants Associated with Primary Hyperoxaluria Type 1

Primary hyperoxaluria type I (PH1) is a rare kidney disease due to the deficit of alanine:glyoxylate aminotransferase (AGT), a pyridoxal-5′-phosphate-dependent enzyme responsible for liver glyoxylate detoxification, which in turn prevents oxalate formation and precipitation as kidney stones. Many PH1-associated missense mutations cause AGT misfolding. Therefore, the use of pharmacological chaperones (PCs), small molecules that promote correct folding, represents a useful therapeutic option. To identify ligands acting as PCs for AGT, we first performed a small screening of commercially available compounds. We tested each molecule by a dual approach aimed at defining the inhibition potency on purified proteins and the chaperone activity in cells expressing a misfolded variant associated with PH1. We then performed a chemical optimization campaign and tested the resulting synthetic molecules using the same approach. Overall, the results allowed us to identify a promising hit compound for AGT and draw conclusions about the requirements for optimal PC activity.

Inhibitors of O-Acetylserine Sulfhydrylase with a Cyclopropane-Carboxylic Acid Scaffold Are Effective Colistin Adjuvants in Gram Negative Bacteria

Antibacterial adjuvants are of great significance, since they allow one to downscale the therapeutic dose of conventional antibiotics and reduce the insurgence of antibacterial resistance. Herein, we report that O-acetylserine sulfhydrylase (OASS) inhibitors could be used as colistin adjuvants to treat infections caused by critical pathogens spreading worldwide, Escherichia coli, Salmonella enterica serovar Typhimurium, and Klebsiella pneumoniae. Starting from a hit compound endowed with a nanomolar dissociation constant, we have rationally designed and synthesized a series of derivatives to be tested against S. Typhimurium OASS isoenzymes, StOASS-A and StOASS-B. All acidic derivatives have shown good activities in the nanomolar range against both OASS isoforms in vitro. Minimal Inhibitory Concentrations (MICs) were then evaluated, as well as compounds’ toxicity. The compounds endowed with good activity in vitro and low cytotoxicity have been challenged as a potential colistin adjuvant against pathogenic bacteria in vitro and the fractional inhibitory concentration (FIC) index has been calculated to define additive or synergistic effects. Finally, the target engagement inside the S. Typhimurium cells was confirmed by using a mutant strain in which the OASS enzymes were inactivated. Our results provide a robust proof of principle supporting OASS as a potential nonessential antibacterial target to develop a new class of adjuvants.

C75 PHEOCHROMOCYTOMA–INDUCED CARDIOGENIC SHOCK: A MULTICENTER ANALYSIS OF CLINICAL PROFILES, MANAGEMENT AND OUTCOMES

Background

Pheochromocytoma is a rare neuroendocrine tumor that arises from the adrenal gland and overproduces catecholamines; it is an infrequent cause of cardiogenic shock (CS). Several case reports have investigated pheochromocytoma–induced CS, but larger studies have not yet been carried out.

Objectives

Our work aims to describe a multicenter experience in the diagnosis and management of patients with pheochromocytoma–induced CS, and to raise awareness around this rare condition. Methods: We enrolled all patients with a diagnosis of pheochromocytoma–induced CS admitted to the intensive care units of 8 European referral Hospitals.

Results

Among the 17 patients (47% males, mean age 49,5 years), we found that pulmonary congestion was the mostly represented clinical feature (82%). The most represented echocardiographic left ventricle (LV) pattern was the reverse Takotsubo (TTS) pattern with apical hyperkinesis associated with basal– to mid–ventricular hypokinesis (47%). Elevated systemic vascular resistances (SVR) were observed. Endomyocardial biopsy of the LV was performed in one patient showing contraction band necrosis, oedema and inflammatory reaction. 76% of patients were treated with dobutamine, 70% needed noradrenaline, 29% adrenaline, 23.5% were treated with levosimendan and 17% with milrinone. Mechanical circulatory support devices (MCS) were necessary for 65% of patients. All patients benefited from pheochromocytoma’s surgical excision, with 4 patients operated on while under ECLS. All patients recovered, excepted one (presenting a severe left ventricular dilatation at admission) who required cardiac transplantation.

Conclusion

Pheochromocytoma is an infrequent cause of CS, with most often a TTS–like presentation. It should be suspected in case of a CS with high initial SVR and rapid deterioration. MCS must be considered in the most severe cases. The main challenge is to stabilize the patient, mostly with MCS, since it remains a reversible cause of CS with a low mortality rate. Adrenalectomy can safely be performed even when the patient is under MCS.

The presence and extent of coronary microvascular dysfunction is associated to the severity of cardiomyopathy in patients with Fabry disease

Funding Acknowledgements

Type of funding sources: None.

Background

Coronary microvascular dysfunction (CMD) occurs before left ventricular hypertrophy (LVH) in Anderson Fabry Disease (AFD). Few data exist about the role of CMD in Fabry cardiomyopathy, when overt LVH has already established.

Purpose

Aim of our study was to assess the relationship between CMD and clinical and echocardiographic features in a cohort of Fabry cardiomyopathy patients.

Methods

We performed coronary CT scan to exclude epicardial coronary artery disease (CAD) in 27 AFD cardiomyopathy patients with angina and/or evidence of silent ischemia at treadmill stress test. All consenting patients with no CAD (n = 17) were submitted to resting and stress 13N-Ammonia myocardial perfusion PET/CT to assess the presence of CMD. All patients also underwent complete echocardiography. Patients were followed-up for 17.3 ± 12.5 months.

Results

Global coronary flow reserve (CFR) resulted <2.5 in 7 (41%) patients. Global stress myocardial blood flow (MBF) was <1.85 mL/min/g in 5 (29%) patients. Global transmural perfusion gradient (TPG, subendocardial MBF/subepicardial MBF) during stress was <1.0 in 13/17 (76.5%) patients. Resting global TPG was ≥1 in 16 (94%) patients. Patients with CFR < 2.5 were older (p = 0.02), had more severe LVH (maximal wall thickness p = 0.04), worst global longitudinal strain (p = 0.03) and E/e’ (p = 0.04) and higher troponin levels (p = 0.002) as compared to patients with CFR ≥ 2.5. They also performed less at treadmill stress (METs p = 0.045). No variables were associated to major cardiovascular events at multivariable analysis.

Conclusions

In Fabry cardiomyopathy patients with angina and/or evidence of silent ischemia, the prevalence of CMD is high and it is associated to a more severe cardiac phenotype, including cardiac biomarker and functional capacity. We are not able to draw any conclusion on the possible prognostic role of CMD in Fabry cardiomyopathy.

Functional capacity and gender-related differences in Fabry disease

Background

Fabry disease (FD) is a rare x-linked lysosomal storage disease characterized by accumulation of glicosphingolipids in several organs, including the heart. Cardiac involvement manifests as left ventricular (LV) hypertrophy, often complicated by myocardial fibrosis. The impact of disease on functional capacity is not well defined, as well as the potential gender-related differences.

Aim

To evaluate the functional capacity in a cohort of FD patients with different degree of cardiac involvement.

Methods

Seventy-two patients were prospectively enrolled from March 2015 to December 2019. Patients underwent cardiac magnetic resonance (CMR) and cardiopulmonary exercise test (CPET) with cycle ergometer. In addition to standard CPET parameters, Chronotropic Index (CI) was calculated as (HR max − HR rest) / (HR max predicted − HR rest), adjusting with HR max predicted calculated as 119 + (HR rest/2) − (age/2) in case of beta-blockers treatment.

Results

CMR showed left ventricle (LV) hypertrophy (LV mass greater than normal reference value) in 36.1% of patients, LGE and reduced T1 values were detected in 30.6% and 59.7% of subjects respectively. Twenty-eight patients were males (39%), the median age was 40 (28–54) [median (25th–75th)] years and only 11 (15%) subjects were on beta-blockers. All subjects performed a maximal test [RQ max = 1.21 (1.14–1.26)] using a ramp protocol of 15 (15–20) Watt. The absolute peakVO2 was 18.2 (15.75–24.08) mL/min/kg, whilst the percentage of predicted peakVO2 was 67.7 (57.3–76.6)%. The chronotropic response of the overall population was characterized by reduced peak heart rate (HRmax) [80.3 (73.8–87.6)% of predicted], and diminished chronotropic index (CI) [0.67 (0.55–0.77) normal value: 0.80], but preserved heart rate reserve (HRR) [21 (12–28) bpm]. Ventilatory efficiency was preserved [VE/VCO2 = 25.70 (23.18–28.00)]. At gender analysis, men showed higher absolute peakVO2 [men vs females: 19.95 (17.20–28.28) vs 17.80 (15.50–21.28) mL/min/kg, p=0.02] but lower percentage of predicted [64.24 (52.58–70.61) vs 70.75 (59.05–78.02)%, p<0.001] than females. No differences between genders were observed in chronotropic response [HRmax = 138 (108–154) vs 142 (135–153) bpm, p=0.38; HRR = 22 (13–36) vs 20 (11–26), p=0.097; CI: 0.67 (0.51–0.76) vs 0.67 (0.58–0.79), p=0.33], whilst females showed a lower peak O2 pulse (VO2/HR) than males [men vs females: 12.08 (10.04–13.64) vs 7.76 (6.88–9.22), p<0.001], possibly related to gender differences in LV dimensions and stroke volume.

Conclusions

This large cohort of FD patients with different degree of cardiac involvement showed a significantly impaired functional capacity, mainly characterized by relevant chronotropic incompetence (independent from the use of beta-blockers), consistent with systemic autonomic dysfunction. The degree of chronotropic incompetence was similar between the genders, but females showed higher predicted peakVO2 despite a lower peak O2 pulse.

Funding Acknowledgement

Type of funding sources: None.

Effect of migalastat on cardiac involvement in Fabry disease: preliminary results from MAIORA study

Background

Fabry Disease (FD) is a rare X-linked lysosomal storage disorder. Since 2016, pharmacological chaperone Migalastat has been approved for treatment of FD patients with amenable mutations to stabilize defective forms of the enzyme α-galactosidase A. A small but significant reduction in left ventricular (LV) mass after 18 months of Migalastat treatment has been previously reported by echocardiography. However, an integrated assessment of the effect of Migalastat on cardiac involvement, combining LV morphology and tissue composition by CMR with exercise capacity by cardiopulmonary test, is lacking.

Purpose

To determine the effects of 18 month treatment with Migalastat on LV mass, native T1 value and functional capacity in naïve patients with genetically confirmed FD cardiomyopathy.

Methods

Sixteen treatment naïve FD patients (4 females, mean age 46.4±16.2) with amenable mutations and signs of cardiac involvement underwent CMR with T1 mapping and cardio-pulmonary testing before and after 18 months of migalastat therapy as a part of MAIORA Study. Cardiac involvement was defined as presence of reduced native T1 values at CMR (a surrogate of myocardial glycosphingolipid storage) and/or LV hypertrophy (LVH). Nine patients (56%, 2 females, mean age 56.4±12.7 years) had LVH at baseline.

Results

Migalastat treatment was well tolerated in all patients, with no serious adverse event. No change in LV mass was detected at 18 months compared to baseline (95.2 (66.0–184.0) vs 103.0 (71.0–182.0) g/m2; p=0.5516). The same result was found after stratifying patients according to presence/absence of Late Gadolinium Enhancement (LGE) (LGE+ n=8, 2 females, mean age 56.2±13.1 years). There was a trend towards an increased native septal T1 value (870.0 (848–882) vs 860.0 (833.0–875.0) ms at baseline; p 0.056) with unchanged extracellular volume (ECV) (0.26 (0.23–0.028) vs 0.26 (0.22–0.29) at baseline; p 0.276) in the overall cohort. An improvement in functional capacity with a trend towards an increase in percent-predicted peak VO2 (72.0 (61.25–80.75) vs 67.0 (45.2–79.2) at baseline; p 0.056) and a significant increase in VO2 at anaerobic threshold (14.8 (12.6–20.0) vs 13.10 (6.8–18.6) ml/kg/min at baseline; p 0.004) was reported in the total population.

Conclusion

In treatment naïve FD patients with amenable mutations and signs of early or overt cardiac involvement, 18-month treatment with Migalastat stabilized LV mass both in patients with and without LGE and was associated with an improvement in exercise tolerance. The trend towards an increase in T1 value associated with unchanged ECV suggests partial clearance of cardiomyocyte glycoshingolipid storage. These real-world data are consistent with a beneficial impact of migalastat on the progression of cardiac involvement in FD.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Amicus Therapeutics

Mechanical dispersion identifies patients with extensive electroanatomic abnormalities in Brugada syndrome

Background

Brugada syndrome (BrS) was initially described as a pure electrical disorder caused by ion channel abnormalities in the absence of structural heart disease. However, imaging, autopsy and endomyocardial biopsy studies have increasingly demonstrated in patients with BrS the presence of myocardial structural alterations of the right ventricle (RV), particularly in the outflow tract. Indeed, electroanatomic mapping studies identified electroanatomic abnormalities of the RV outflow tract in both unipolar and bipolar maps with a significant correlation between the extension of low-voltage areas and the inducibility of arrhythmias at electrophysiological study or the incidence of malignant arrhythmias during the follow up. New echocardiographic parameters have been proposed to identify subtle myocardial alterations associated with arrhythmic events. Mechanical dispersion (MD) of the left ventricle (LV) has been identified as a prognostic marker in the arrhythmic risk stratification in various cardiac diseases including some cardiomyopathies.

Purpose

In this study we evaluated MD and global longitudinal strain (GLS) of RV and LV in patients with BrS to identify echocardiographic correlates of the abnormalities detected by electroanatomic mapping.

Methods

We performed 2D-Echocardiography with speckle tracking analysis of RV and LV in patients with BrS previously submitted to RV electroanatomic mapping. All studies were performed by investigators blind to clinical features and electrophysiological findings. Echocardiographic data were compared with electroanatomic mapping and electrophysiological study findings and with clinical data.

Results

We enrolled 18 patients (52±11 years, male 44%). Patients with a LV MD value ≥40 ms showed a pathological unipolar area with voltage <5.5 mV significantly more extended than patients with a LV MD value <40 ms (28.49±21.06 vs 10.47±8.22; p=0.03). Patients with LV MD ≥40 ms also showed a trend to greater extension of the unipolar area with voltage <4 mV (13.94±13.11 vs 4.94±3.12; p=0.07), a greater extension of the bipolar area with voltage <1.5 mV (6.24±5.22 vs 2.24±3.15; p=0.07) and higher inducibility at programmed ventricular stimulation (70% vs 37.5%, p=0.34). No correlation was observed between RV MD or GLS values and the extent of the low-voltage areas or with the presence of genetic mutations associated with BrS.

Conclusions

In patients with BrS a LV MD ≥40 ms is associated with a greater extension of low-voltage areas at unipolar mapping. Echocardiographic evaluation with MD analysis may represent a valuable non-invasive tool to identify electroanatomic alterations prompting further invasive studies including electronatomic mapping and electrophysiological study. Prospective studies on larger series may further clarify the potential role of MD and electroanatomic mapping in the prognostic stratification of patients with BrS.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Crystal structure of Aspergillus fumigatus AroH, an aromatic amino acid aminotransferase

Aspergillus fumigatus is a saprophytic ubiquitous fungus whose spores can trigger reactions such as allergic bronchopulmonary aspergillosis or the fatal invasive pulmonary aspergillosis. To survive in the lungs, the fungus must adapt to a hypoxic and nutritionally restrictive environment, exploiting the limited availability of aromatic amino acids (AAAs) in the best possible way, as mammals do not synthesize them. A key enzyme for AAAs catabolism in A. fumigatus is AroH, a pyridoxal 5′‐phosphate‐dependent aromatic aminotransferase. AroH was recently shown to display a broad substrate specificity, accepting L‐kynurenine and α‐aminoadipate as amino donors besides AAAs. Given its pivotal role in the adaptability of the fungus to nutrient conditions, AroH represents a potential target for the development of innovative therapies against A. fumigatus‐related diseases. We have solved the crystal structure of Af‐AroH at 2.4 Å resolution and gained new insight into the dynamics of the enzyme's active site, which appears to be crucial for the design of inhibitors. The conformational plasticity of the active site pocket is probably linked to the wide substrate specificity of AroH.

Towards the sustainable discovery and development of new antibiotics

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics. We propose both short-term and long-term solutions to overcome the most urgent limitations in the various sectors of research and funding, aiming to bridge the gap between academic, industrial and political stakeholders, and to unite interdisciplinary expertise in order to efficiently fuel the translational pipeline for the benefit of future generations.

Antimicrobial resistance is an increasing threat to public health and encouraging the development of new antimicrobials is one of the most important ways to address the problem. This Roadmap article aims to bring together industrial, academic and political partners, and proposes both short-term and long-term solutions to this challenge.

Left atrial morpho-functional changes in hypertrophic cardiomyopathy and Fabry disease: a CMR-feature tracking study

Funding Acknowledgements

Type of funding sources: None.

Background

Left ventricular (LV) diastolic dysfunction (DD) is a hallmark of hypertrophic cardiomyopathy (HCM) and its phenocopies, such as Fabry disease (FD). Together with left atrial (LA) size, LA function is emerging as a sensitive marker of the adaptive changes to backward transmission of LV cardiac filling pressure, thus implementing DD assessment. Additionally, both HCM and FD are characterized by a primitive atrial myopathy, but LA morpho-functional changes in HCM and FD have never been directly compared. More recently, LA strain by Cardiovascular Magnetic Resonance Feature Tracking (CMR-FT) has been demonstrated to be a feasible and reproducible tool to explore LA function.

Purpose

To compare LA morpho-functional changes in HCM and FD and to explore their correlation with tissue alterations.

Methods

15 HCM and 15 sex-, age- and LV mass index-matched FD patients underwent CMR (Magnetom Aera 1.5T, Siemens) and Doppler Echocardiography for LV diastolic function assessment (E/e’ and DD grading from 0 to 3). LA phasic function was evaluated by CMR-FT strain (Qstrain Medis). The software output included passive (εe, conduit function), active (εa, booster pump function) and total strain (εs, reservoir function), along with LA volumes and ejection fraction (EF). Late gadolinium enhancement (LGE) was quantified as a percentage of LV mass using the standard deviations (SDs) method (≥ 5 SDs). Interstitial fibrosis was assessed by extracellular volume (ECV) quantification in remote myocardium. All patients were in sinus rhythm.

Results

In the HCM group, the proportion of patients with DD grade 2-3 was only slightly higher than in FD (p 0.26). Accordingly, no significant difference was found in E/e’ value (p 0.78). Compared to FD, HCM patients showed more severe LA morpho-functional changes, including larger LA end-systolic volume (ESV) (113 ± 35 vs 84 ± 23 ml), lower LA EF (37 ± 7 vs 44 ± 9 %) and a greater reduction of εs (-20 ± 5 vs -25 ± 6 %) and εa (-10 ± 4 vs -15 ± 4 %) (all p < 0.05). LV size and function and the burden of fibrosis (LGE quantification and ECV) were comparable between the two groups. Interestingly, in HCM population, unlike in FD, LA morpho-functional measurements significantly correlated with tissue characterization parameters (LA ESV with LGE, r 0.56, p 0.03; εs and εa with ECV, r -0.51, p 0.05 and r -0.59, p 0.02, respectively).

Conclusions

LA morpho-functional alterations are much more severe in HCM compared to FD with similar degree of LV hypertrophy. A more severe atrial myopathy or different mechanisms of atrial damage in the two cardiomyopathies may explain these findings. LA CMR-FT analysis may represent a sensitive tool to discriminate between HCM and FD, although larger studies are needed to confirm this finding and the possible correlation with the occurrence of atrial arrhythmias and thromboembolic risk.

Discovery of Substituted (2-Aminooxazol-4-yl)Isoxazole-3-carboxylic Acids as Inhibitors of Bacterial Serine Acetyltransferase in the Quest for Novel Potential Antibacterial Adjuvants

Many bacteria and actinomycetales use L-cysteine biosynthesis to increase their tolerance to antibacterial treatment and establish a long-lasting infection. In turn, this might lead to the onset of antimicrobial resistance that currently represents one of the most menacing threats to public health worldwide. The biosynthetic machinery required to synthesise L-cysteine is absent in mammals; therefore, its exploitation as a drug target is particularly promising. In this article, we report a series of inhibitors of Salmonella thyphimurium serine acetyltransferase (SAT), the enzyme that catalyzes the rate-limiting step of L-cysteine biosynthesis. The development of such inhibitors started with the virtual screening of an in-house library of compounds that led to the selection of seven structurally unrelated hit derivatives. A set of molecules structurally related to hit compound 5, coming either from the original library or from medicinal chemistry efforts, were tested to determine a preliminary structure–activity relationship and, especially, to improve the inhibitory potency of the derivatives, that was indeed ameliorated by several folds compared to hit compound 5 Despite these progresses, at this stage, the most promising compound failed to interfere with bacterial growth when tested on a Gram-negative model organism, anticipating the need for further research efforts.

Investigational Studies on a Hit Compound Cyclopropane-Carboxylic Acid Derivative Targeting O-Acetylserine Sulfhydrylase as a Colistin Adjuvant

Antibacterial adjuvants are of great significance, since they allow the therapeutic dose of conventional antibiotics to be lowered and reduce the insurgence of antibiotic resistance. Herein, we report that an O-acetylserine sulfhydrylase (OASS) inhibitor can be used as a colistin adjuvant to treat infections caused by Gram-positive and Gram-negative pathogens. A compound that binds OASS with a nM dissociation constant was tested as an adjuvant of colistin against six critical pathogens responsible for infections spreading worldwide, Escherichia coli, Salmonella enterica serovar Typhimurium, Klebisiella pneumoniae, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Staphylococcus pseudintermedius. The compound showed promising synergistic or additive activities against all of them. Knockout experiments confirmed the intracellular target engagement supporting the proposed mechanism of action. Moreover, compound toxicity was evaluated by means of its hemolytic activity against sheep defibrinated blood cells, showing a good safety profile. The 3D structure of the compound in complex with OASS was determined at 1.2 Å resolution by macromolecular crystallography, providing for the first time structural insights about the nature of the interaction between the enzyme and this class of competitive inhibitors. Our results provide a robust proof of principle supporting OASS as a potential nonessential antibacterial target to develop a new class of adjuvants and the structural basis for further structure-activity relationship studies.

Regulatory T Cells in Severe Persistent Asthma in the Era of Monoclonal Antibodies Target Therapies

Asthma is an immunoinflammatory disease characterized by bronchial hyper-reactivity to different external stimuli. New monoclonal target treatments have been developed, but few studies have investigated the role of regulatory T cells in severe asthma and the modulatory effect of biological therapy on regulatory T cell functions. Their dysfunction may contribute to the development and exacerbation of asthma. Here we review the recent literature on the potential immunological role of regulatory T cells in the pathogenesis of severe asthma. The analysis of the role of regulatory T cells was performed in terms of functions and their possible interactions with mechanisms of action of the novel treatment for severe asthma. In an era of biological therapies for severe asthma, little data is available on the potential effects of what could be a new therapy: monoclonal antibody targeting of regulatory T cell numbers and functions.

Aspergillus fumigatus tryptophan metabolic route differently affects host immunity

Indoleamine 2,3-dioxygenases (IDOs) degrade l-tryptophan to kynurenines and drive the de novo synthesis of nicotinamide adenine dinucleotide. Unsurprisingly, various invertebrates, vertebrates, and even fungi produce IDO. In mammals, IDO1 also serves as a homeostatic regulator, modulating immune response to infection via local tryptophan deprivation, active catabolite production, and non-enzymatic cell signaling. Whether fungal Idos have pleiotropic functions that impact on host-fungal physiology is unclear. Here, we show that Aspergillus fumigatus possesses three ido genes that are expressed under conditions of hypoxia or tryptophan abundance. Loss of these genes results in increased fungal pathogenicity and inflammation in a mouse model of aspergillosis, driven by an alternative tryptophan degradation pathway to indole derivatives and the host aryl hydrocarbon receptor. Fungal tryptophan metabolic pathways thus cooperate with the host xenobiotic response to shape host-microbe interactions in local tissue microenvironments.

Progressive electrocardiographic changes in parallel with cardiac magnetic resonance findings in fabry disease

Background

Cardiac Magnetic Resonance (CMR) allows to detect progressive stages of cardiac involvement in Fabry Disease (FD). A systematic description of electrocardiographic (ECG) alterations occurring in FD is currently missing.

Purpose

To explore ECG changes in progressive stages of FD cardiomyopathy.

Methods

71 FD patients and 17 healthy controls underwent CMR with T1 mapping and 12-lead ECG. ECG analysis included the duration of the P-wave and the interval between the end of P-wave and the beginning of QRS (PendQ). FD patients in the test cohort were divided into 3 groups with increasing severity of cardiac involvement: A) normal T1, no LVH; B) low T1, no LVH; C) low T1, LVH.

Results

An increase of Pwave/PendQ ratio was observed in Group A compared to Controls (1.08 vs. 0.75, p<0.0001). Higher Pwave/PendQ ratio (1.50 vs. 1.08, p<0.0001), shorter PQc interval (127.9 vs. 159.5, p=0.0007), increased Sokolow-Lyon Index (SLI) (3.2 vs. 2.4, p<0,001) and T wave amplitude (0.6 vs. 0.4 mV, p=0.002) characterized Group B in comparison with Group A. A higher prevalence of left bundle branch blocks (13.6% vs. 0%, p=0.03) and repolarization abnormalities (77.3% vs. 5.7%), wider QRS (120 vs 95 msec, p<0.0001) and QT (460 vs 400 msec, p=0.003) intervals were found in Group C compared to Group B. SLI (AUC 0.769), Pwave/PendQ (AUC 0.778), QRS (AUC 0.703) and QT (AUC 0.769) durations resulted to be independent predictors of low T1 values on CMR at stepwise multivariate analysis.

Conclusion

FD is characterized by progressive ECG changes. The identification of ECG parameters able to predict a lowering of myocardial T1 values on CMR may promote early detection of cardiac involvement, helping to target the therapeutic approach.

Progressive ECG and CMR changes in FD

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): This study was partially supported by Ricerca Corrente funding from the Italian Ministry of Health to IRCCS Policlinico San Donato.

Nitric oxide-releasing cyclodextrins as biodegradable antibacterial scaffolds: a patent evaluation of US2019343869(A1)

INTRODUCTION

Antimicrobial resistance is one of the major scourges for health care worldwide; therefore, novel investigational approaches are needed to potentiate and preserve the current antibacterial arsenal. Cyclodextrins are known to improve the formulability of several different therapeutic agents. When functionalized with nitric oxide (NO) releasing groups, and suitably loaded with an antibacterial or antitumoral agents, they can exert additive activity, especially toward certain bacterial strains and cell cancer lines.

AREAS COVERED

US2019343869 describes NO-releasing cyclodextrins, a method for their synthesis, a composition that is based on them, and their application as anticancer or antibacterial agents, especially toward planktonic P. aeruginosa and the biofilm resulting from infection. Anticancer activity is measured against A549 cells. The amount of NO released is in the range of 0.5 μmol to 2.5 μmol per milligram of functionalized cyclodextrin with a half-life for NO release in a range of between about 0.7-4.2 hours.

EXPERT OPINION

The results support the use of NO-releasing cyclodextrins as a matrix for the delivery of antibacterial and anticancer drugs in a suitable formulation. However, antibacterial activity seems to be weak, and more focused studies are needed.

2-Aminooxazole as a Novel Privileged Scaffold in Antitubercular Medicinal Chemistry

To obtain effective eradication of numerous infectious diseases such as tuberculosis, it is important to supply the medicinal chemistry arsenal with novel chemical agents. Isosterism and bioisosterism are widely known concepts in the field of early drug discovery, and in several cases, rational isosteric replacements have contributed to improved efficacy and physicochemical characteristics throughout the hit-to-lead optimization process. However, sometimes the synthesis of isosteres might not be as straightforward as that of the parent compounds, and therefore, novel synthetic strategies must be elaborated. In this regard, we herein report the evaluation of a series of N-substituted 4-phenyl-2-aminooxazoles that, despite being isosteres of a widely used nucleus such as the 2-aminothiazole, have been only seldom explored. After elaboration of a convenient synthetic strategy, a small set of 2-aminothiazoles and their 2-aminooxazole counterparts were compared with regard to antitubercular activity and physicochemical characteristics.

Inhibition of Nonessential Bacterial Targets: Discovery of a Novel Serine O-Acetyltransferase Inhibitor

In ϒ-proteobacteria and Actinomycetales, cysteine biosynthetic enzymes are indispensable during persistence and become dispensable during growth or acute infection. The biosynthetic machinery required to convert inorganic sulfur into cysteine is absent in mammals; therefore, it is a suitable drug target. We searched for inhibitors of Salmonella serine acetyltransferase (SAT), the enzyme that catalyzes the rate-limiting step of l-cysteine biosynthesis. The virtual screening of three ChemDiv focused libraries containing 91 243 compounds was performed to identify potential SAT inhibitors. Scaffold similarity and the analysis of the overall physicochemical properties allowed the selection of 73 compounds that were purchased and evaluated on the recombinant enzyme. Six compounds displaying an IC₅₀ <100 μM were identified via an indirect assay using Ellman's reagent and then tested on a Gram-negative model organism, with one of them being able to interfere with bacterial growth via SAT inhibition.

P956 Prognostic role of right ventricular hypertrophy in anderson fabry disease

Background

Right ventricular hypertrophy (RVH) is a common finding in Anderson Fabry disease (AFD). In other infiltrative and storage cardiomyopathies right ventricular (RV) involvement may influence prognostic stratification. Nevertheless, the prognostic implications of right ventricle involvement in AFD have never been assessed.

Purpose

Evaluation of the prognostic significance of RVH and RV systolic function in AFD cardiomyopathy.

Methods

Forty-five AFD patients (56% male) with extensive baseline evaluation, including assessment of RVH and RV systolic function, were followed-up for an average of 44.9 ± 8.5 months. RV systolic function was assessed by standard and tissue Doppler echocardiography and quantified using RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE) and Systolic tissue Doppler velocity of the tricuspid annulus (RV Sa). Cardiovascular events were defined as new-onset atrial fibrillation, heart failure or pace-maker implantation; renal events were defined as progression to dialysis and/or renal transplantation or significant worsening of glomerular filtration rate; cerebrovascular events were defined as stroke or transient ischemic attack. The outcome was defined as the time to death or the first event in any of the above predefined categories.

Results

Fourteen patients (31.1%) presented RVH, while RV systolic function was normal in all cases. During the follow-up period, 13 patients (28.8%, 11 male) experienced major events including two deaths. Pace-maker implantation (6 cases) was the most common type of event. At univariate analysis several variables were associated with the occurrence of events, including RVH and indexes of RV systolic function. However, at multivariate analysis only proteinuria (HR:8.3, 95% CI: 2.88 to 23.87, p ˂0.001) and LV mass indexed (HR: 1.01, 95% CI: 1.00 to 1.03, p = 0.03) were independent predictors of outcome.

Conclusions

The presence and extension of RVH is not associated with outcome in AFD. Our study confirms that at variance with other infiltrative or storage cardiomyopathies, RV involvement in AFD is an innocent bystander and does not influence prognosis.

Sodium Hyaluronate Nanocomposite Respirable Microparticles to Tackle Antibiotic Resistance with Potential Application in Treatment of Mycobacterial Pulmonary Infections

Tuberculosis resistant cases have been estimated to grow every year. Besides Mycobacterium tuberculosis, other mycobacterial species are responsible for an increasing number of difficult-to-treat infections. To increase efficacy of pulmonary treatment of mycobacterial infections an inhalable antibiotic powder targeting infected alveolar macrophages (AMs) and including an efflux pump inhibitor was developed. Low molecular weight sodium hyaluronate sub-micron particles were efficiently loaded with rifampicin, isoniazid and verapamil, and transformed in highly respirable microparticles (mean volume diameter: 1 μm) by spray drying. These particles were able to regenerate their original size upon contact with aqueous environment with mechanical stirring or sonication. The in vitro drugs release profile from the powder was characterized by a slow release rate, favorable to maintain a high drug level inside AMs. In vitro antimicrobial activity and ex vivo macrophage infection assays employing susceptible and drug resistant strains were carried out. No significant differences were observed when the powder, which did not compromise the AMs viability after a five-day exposure, was compared to the same formulation without verapamil. However, both preparations achieved more than 80% reduction in bacterial viability irrespective of the drug resistance profile. This approach can be considered appropriate to treat mycobacterial respiratory infections, regardless the level of drug resistance.

Biochemical Characterization of Aspergillus fumigatus AroH, a Putative Aromatic Amino Acid Aminotransferase

The rise in the frequency of nosocomial infections is becoming a major problem for public health, in particular in immunocompromised patients. Aspergillus fumigatus is an opportunistic fungus normally present in the environment directly responsible for lethal invasive infections. Recent results suggest that the metabolic pathways related to amino acid metabolism can regulate the fungus-host interaction and that an important role is played by enzymes involved in the catabolism of L-tryptophan. In particular, in A. fumigatus L-tryptophan regulates Aro genes. Among them, AroH encodes a putative pyridoxal 5'-phosphate-dependent aminotransferase. Here we analyzed the biochemical features of recombinant purified AroH by spectroscopic and kinetic analyses corroborated by in silico studies. We found that the protein is dimeric and tightly binds the coenzyme forming a deprotonated internal aldimine in equilibrium with a protonated ketoenamine form. By setting up a new rapid assay method, we measured the kinetic parameters for the overall transamination of substrates and we demonstrated that AroH behaves as an aromatic amino acid aminotransferase, but also accepts L-kynurenine and α-aminoadipate as amino donors. Interestingly, computational approaches showed that the predicted overall fold and active site topology of the protein are similar to those of its yeast ortholog, albeit with some differences in the regions at the entrance of the active site, which could possibly influence substrate specificity. Should targeting fungal metabolic adaptation be of therapeutic value, the results of the present study may pave the way to the design of specific AroH modulators as potential novel agents at the host/fungus interface.

Refining the structure-activity relationships of 2-phenylcyclopropane carboxylic acids as inhibitors of O-acetylserine sulfhydrylase isoforms

The lack of efficacy of current antibacterials to treat multidrug resistant bacteria poses a life-threatening alarm. In order to develop enhancers of the antibacterial activity, we carried out a medicinal chemistry campaign aiming to develop inhibitors of enzymes that synthesise cysteine and belong to the reductive sulphur assimilation pathway, absent in mammals. Previous studies have provided a novel series of inhibitors for O-acetylsulfhydrylase – a key enzyme involved in cysteine biosynthesis. Despite displaying nanomolar affinity, the most active representative of the series was not able to interfere with bacterial growth, likely due to poor permeability. Therefore, we rationally modified the structure of the hit compound with the aim of promoting their passage through the outer cell membrane porins. The new series was evaluated on the recombinant enzyme from Salmonella enterica serovar Typhimurium, with several compounds able to keep nanomolar binding affinity despite the extent of chemical manipulation.

Discovering a new class of antifungal agents that selectively inhibits microbial carbonic anhydrases

Infections caused by pathogens resistant to the available antimicrobial treatments represent nowadays a threat to global public health. Recently, it has been demonstrated that carbonic anhydrases (CAs) are essential for the growth of many pathogens and their inhibition leads to growth defects. Principal drawbacks in using CA inhibitors (CAIs) as antimicrobial agents are the side effects due to the lack of selectivity toward human CA isoforms. Herein we report a new class of CAIs, which preferentially interacts with microbial CA active sites over the human ones. The mechanism of action of these inhibitors was investigated against an important fungal pathogen, Cryptococcus neoformans, revealing that they are also able to inhibit CA in microbial cells growing in vitro. At our best knowledge, this is the first report on newly designed synthetic compounds selectively targeting β-CAs and provides a proof of concept of microbial CAs suitability as an antimicrobial drug target.

Discovery of novel fragments inhibiting O-acetylserine sulphhydrylase by combining scaffold hopping and ligand-based drug design

Several bacteria rely on the reductive sulphur assimilation pathway, absent in mammals, to synthesise cysteine. Reduction of virulence and decrease in antibiotic resistance have already been associated with mutations on the genes that codify cysteine biosynthetic enzymes. Therefore, inhibition of cysteine biosynthesis has emerged as a promising strategy to find new potential agents for the treatment of bacterial infection. Following our previous efforts to explore OASS inhibition and to expand and diversify our library, a scaffold hopping approach was carried out, with the aim of identifying a novel fragment for further development. This novel chemical tool, endowed with favourable pharmacological characteristics, was successfully developed, and a preliminary Structure–Activity Relationship investigation was carried out.

Adjuvant therapies against tuberculosis: discovery of a 2-aminothiazole targeting Mycobacterium tuberculosis energetics

AIM

To evaluate the activity of the 2-aminothiazole UPAR-174 following an unexplored approach: targeting Mycobacterium tuberculosis with lipophilic compounds that present antituberculosis and efflux inhibitory activity.

METHODS

Antituberculosis activity was assessed against replicating, nonreplicating and intracellular bacilli. Its capacity to inhibit active efflux was determined. ATP quantification and membrane potential analysis were performed. Intracellular activity was studied on human-monocyte-derived macrophages.

RESULTS

UPAR-174 is an efflux inhibitor active against replicating, nonreplicating and intracellular M. tuberculosis. It dissipates the membrane potential and causes ATP depletion.

CONCLUSION

Targeting M. tuberculosis with lipophilic efflux inhibitors, exploring their dual activity - dissipation of the proton motive force and efflux inhibition - represents an attractive strategy to fight against drug-resistant tuberculosis.

In vitro Digestion of Zingiber officinale Extract and Evaluation of Stability as a First Step to Determine its Bioaccesibility

Zingiber officinale (Ginger) is one of the most spice used worldwide and since antiquity it has been used in traditional medicine to treat different diseases. Although ginger is generally considered safe, there are no more information about the mechanism of its therapeutic action and its nutraceutical value. For these reasons the purpose of this work is to apply in vitro digestion model, as the first step in the study of its bioaccessibility, to understand which is the fate of its bioactive compounds after ingestion. This allow us to characterize which ginger metabolite are stable under gastrointestinal conditions and, thus, available for intestinal absorption. The aim of this study is to provide valuable information to better understand ginger pharmacological activities, paving the way for the definition of suitable dosage and source of food matrices to ensure nutritional efficacy.

Challenging the Drug-Likeness Dogma for New Drug Discovery in Tuberculosis

The emergence of multi- and extensively drug resistant tuberculosis worldwide poses a great threat to human health and highlight the need to discover and develop new, effective and inexpensive antituberculosis agents. High-throughput screening assays against well-validated drug targets and structure based drug design have been employed to discover new lead compounds. However, the great majority fail to demonstrate any antimycobacterial activity when tested against Mycobacterium tuberculosis in whole-cell screening assays. This is mainly due to some of the intrinsic properties of the bacilli, such as the extremely low permeability of its cell wall, slow growth, drug resistance, drug tolerance, and persistence. In this sense, understanding the pathways involved in M. tuberculosis drug tolerance, persistence, and pathogenesis, may reveal new approaches for drug development. Moreover, the need for compounds presenting a novel mode of action is of utmost importance due to the emergence of resistance not only to the currently used antituberculosis agents, but also to those in the pipeline. Cheminformatics studies have shown that drugs endowed with antituberculosis activity have the peculiarity of being more lipophilic than many other antibacterials, likely because this leads to improved cell penetration through the extremely waxy mycobacterial cell wall. Moreover, the interaction of the lipophilic moiety with the membrane alters its stability and functional integrity due to the disruption of the proton motive force, resulting in cell death. When a ligand-based medicinal chemistry campaign is ongoing, it is always difficult to predict whether a chemical modification or a functional group would be suitable for improving the activity. Nevertheless, in the “instruction manual” of medicinal chemists, certain functional groups or certain physicochemical characteristics (i.e., high lipophilicity) are considered red flags to look out for in order to safeguard drug-likeness and avoid attritions in the drug discovery process. In this review, we describe how antituberculosis compounds challenge established rules such as the Lipinski's “rule of five” and how medicinal chemistry for antituberculosis compounds must be thought beyond such dogmatic schemes.

Efflux Activity Differentially Modulates the Levels of Isoniazid and Rifampicin Resistance among Multidrug Resistant and Monoresistant Mycobacterium tuberculosis Strains

With the growing body of knowledge on the contribution of efflux activity to Mycobacterium tuberculosis drug resistance, increased attention has been given to the use of efflux inhibitors as adjuvants of tuberculosis therapy. Here, we investigated how efflux activity modulates the levels of efflux between monoresistant and multi- and extensively drug resistant (M/XDR) M. tuberculosis clinical isolates. The strains were characterized by antibiotic susceptibility testing in the presence/absence of efflux inhibitors, molecular typing, and genetic analysis of drug-resistance-associated genes. Efflux activity was quantified by real-time fluorometry. The results demonstrated that all the M. tuberculosis clinical strains, susceptible or resistant, presented a faster, rapid, and non-specific efflux-mediated short-term response to drugs. The synergism assays demonstrated that the efflux inhibitors were more effective in reducing the resistance levels in the M/XDR strains than in the monoresistant strains. This indicated that M/XDR strains presented a more prolonged response to drugs mediated by efflux compared to the monoresistant strains, but both maintain it as a long-term stress response. This work shows that efflux activity modulates the levels of drug resistance between monoresistant and M/XDR M. tuberculosis clinical strains, allowing the bacteria to survive in the presence of noxious compounds.

An Experimental Model for the Rapid Screening of Compounds with Potential Use Against Mycobacteria

Infections caused by Mycobacterium tuberculosis and other mycobacteria are major challenges for global public health. Particularly worrisome are infections caused by multidrug-resistant bacteria, which are increasingly difficult to treat because of the loss of efficacy of the current antibacterial agents, a problem that continues to escalate worldwide. There has been a limited interest and investment on the development of new antibacterial agents in the past decades. This has led to the current situation, in which there is an urgent demand for innovative therapeutic alternatives to fight infections caused by multidrug-resistant pathogens, such as multidrug-resistant tuberculosis. The identification of compounds that can act as adjuvants in antimycobacterial therapeutic regimens is an appealing strategy to restore the efficacy lost by some of the antibiotics currently used and shorten the duration of the therapeutic regimen. In this work, by setting Mycobacterium smegmatis as a model organism, we have developed a methodological strategy to identify, in a fast and simple approach, compounds with antimycobacterial activity or with potential adjuvant properties, by either inhibition of efflux or other unrelated mechanisms. Such an approach may increase the rate of identification of promising molecules, to be further explored in pathogenic models for their potential use either as antimicrobials or as adjuvants, in combination with available therapeutic regimens for the treatment of mycobacterial infections. This method allowed us to identify a new molecule that shows promising activity as an efflux inhibitor in M. smegmatis.

Substituted N-Phenyl-5-(2-(phenylamino)thiazol-4-yl)isoxazole-3-carboxamides Are Valuable Antitubercular Candidates that Evade Innate Efflux Machinery

Tuberculosis remains one of the deadliest infectious diseases in the world, and the increased number of multidrug-resistant and extremely drug-resistant strains is a significant reason for concern. This makes the discovery of novel antitubercular agents a cogent priority. We have previously addressed this need by reporting a series of substituted 2-aminothiazoles capable to inhibit the growth of actively replicating, nonreplicating persistent, and resistant Mycobacterium tuberculosis strains. Clues from the structure-activity relationships lining up the antitubercular activity were exploited for the rational design of improved analogues. Two compounds, namely N-phenyl-5-(2-(p-tolylamino)thiazol-4-yl)isoxazole-3-carboxamide 7a and N-(pyridin-2-yl)-5-(2-(p-tolylamino)thiazol-4-yl)isoxazole-3-carboxamide 8a, were found to show high inhibitory activity toward susceptible M. tuberculosis strains, with an MIC₉₀ of 0.125-0.25 μg/mL (0.33-0.66 μM) and 0.06-0.125 μg/mL (0.16-0.32 μM), respectively. Moreover, they maintained good activity also toward resistant strains, and they were selective over other bacterial species and eukaryotic cells, metabolically stable, and apparently not susceptible to the action of efflux pumps.

Discovery of New Potential Anti-Infective Compounds Based on Carbonic Anhydrase Inhibitors by Rational Target-Focused Repurposing Approaches

In academia, compound recycling represents an alternative drug discovery strategy to identify new pharmaceutical targets from a library of chemical compounds available in house. Herein we report the application of a rational target-based drug-repurposing approach to find diverse applications for our in-house collection of compounds. The carbonic anhydrase (CA, EC 4.2.1.1) metalloenzyme superfamily was identified as a potential target of our compounds. The combination of a thoroughly validated docking screening protocol, together with in vitro assays against various CA families and isoforms, allowed us to identify two unprecedented chemotypes as CA inhibitors. The identified compounds have the capacity to preferentially bind pathogenic (bacterial/protozoan) CAs over human isoforms and represent excellent hits for further optimization in hit-to-lead campaigns.

A combined ligand- and structure-based approach for the identification of rilmenidine-derived compounds which synergize the antitumor effects of doxorubicin

The clonidine-like central antihypertensive agent rilmenidine, which has high affinity for I1-type imidazoline receptors (I1-IR) was recently found to have cytotoxic effects on cultured cancer cell lines. However, due to its pharmacological effects resulting also from α2-adrenoceptor activation, rilmenidine cannot be considered a suitable anticancer drug candidate. Here, we report the identification of novel rilmenidine-derived compounds with anticancer potential and devoid of α2-adrenoceptor effects by means of ligand- and structure-based drug design approaches. Starting from a large virtual library, eleven compounds were selected, synthesized and submitted to biological evaluation. The most active compound 5 exhibited a cytotoxic profile similar to that of rilmenidine, but without appreciable affinity to α2-adrenoceptors. In addition, compound 5 significantly enhanced the apoptotic response to doxorubicin, and may thus represent an important tool for the development of better adjuvant chemotherapeutic strategies for doxorubicin-insensitive cancers.

Rational Design and Synthesis of Thioridazine Analogues as Enhancers of the Antituberculosis Therapy

Tuberculosis, caused by Mycobacterium tuberculosis, is still one of the leading infectious diseases globally. Therefore, novel approaches are needed to face this disease. Efflux pumps are known to contribute to the emergence of M. tuberculosis drug resistance. Thioridazine has shown good anti-TB properties both in vitro and in vivo, likely due to its capacity to inhibit efflux mechanisms. Here we report the design and synthesis of a number of putative efflux inhibitors inspired by the structure of thioridazine. Compounds were evaluated for their in vitro and ex vivo activity against M. tuberculosis H37Rv. Compared to the parent molecule, some of the compounds synthesized showed higher efflux inhibitory capacity, less cytotoxicity, and a remarkable synergistic effect with anti-TB drugs both in vitro and in human macrophages, demonstrating their potential to be used as coadjuvants for the treatment of tuberculosis.

Cyclopropane derivatives as potential human serine racemase inhibitors: unveiling novel insights into a difficult target

d-Serine is the co-agonist of NMDA receptors and binds to the so-called glycine site. d-Serine is synthesized by human serine racemase (SR). Over activation of NMDA receptors is involved in many neurodegenerative diseases and, therefore, the inhibition of SR might represent a novel strategy for the treatment of these pathologies. SR is a very difficult target, with only few compounds so far identified exhibiting weak inhibitory activity. This study was aimed at the identification of novel SR inhibitor by mimicking malonic acid, the best-known SR inhibitor, with a cyclopropane scaffold. We developed, synthesized, and tested a series of cyclopropane dicarboxylic acid derivatives, complementing the synthetic effort with molecular docking. We identified few compounds that bind SR in high micromolar range with a lack of significant correlation between experimental and predicted binding affinities. The thorough analysis of the results can be exploited for the development of more potent SR inhibitors.

Discovery of antitubercular 2,4-diphenyl-1H-imidazoles from chemical library repositioning and rational design

TB, caused by Mycobacterium tuberculosis, is one of the deadliest infections worldwide. The co-infection with HIV and the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) strains have further increased the burden for this disease. In the attempt to respond to the constant need of novel therapeutic options, we herein report the discovery of 2,4-diphenyl-1H-imidazoles as effective antitubercular agents, with MIC in the low micromolar range against actively replicating and persistent M. tuberculosis strains. The good activity, along with the lack of toxicity and the feasible synthesis, underscore their value as novel scaffolds for the development of new anti-TB drugs.

Further insights into the SAR of α-substituted cyclopropylamine derivatives as inhibitors of histone demethylase KDM1A

Epigenetics alterations including histone methylation and acetylation, and DNA methylation, are thought to play important roles in the onset and progression of cancer in numerous tumour cell lines. Lysine-specific demethylase 1 (LSD1 or KDM1A) is highly expressed in different cancer types and inhibiting KDM1A activity seems to have high therapeutic potential in cancer treatment. In the recent years, several inhibitors of KDM1A have been prepared and disclosed. The majority of these derivatives were designed based on the structure of tranylcypromine, as the cyclopropane core is responsible for the covalent interaction between the inhibitor and the catalytic domain of KDM proteins. In this study, we have further extended the SAR regarding compounds 1a-e, which were recently found to inhibit KDM1A with good activity. The decoration of the phenyl ring at the β-position of the cyclopropane ring with small functional groups, mostly halogenated, and in particular at the meta position, led to a significant improvement of the inhibitory activity against KDM1A, as exemplified by compound 44a, which has a potency in the low nanomolar range (31 nM).