New insight into structure-activity of furan-based salicylate synthase (MbtI) inhibitors as potential antitubercular agents.

Starting from the analysis of the hypothetical binding mode of our previous furan-based hit (I), we successfully achieved our objective to replace the nitro moiety, leading to the disclosure of a new lead exhibiting a strong activity against MbtI. Our best candidate 1 h displayed a Ki of 8.8 µM and its antimycobacterial activity (MIC99 = 250 µM) is conceivably related to mycobactin biosynthesis inhibition. These results support the hypothesis that 5-phenylfuran-2-carboxylic derivatives are a promising class of MbtI inhibitors.

New Chromane-Based Derivatives as Inhibitors of Mycobacterium tuberculosis Salicylate Synthase (MbtI): Preliminary Biological Evaluation and Molecular Modeling Studies.

Tuberculosis is the leading cause of death from a single infectious agent worldwide; therefore, the need for new antitubercular drugs is desperate. The recently validated target salicylate synthase MbtI is the first enzyme involved in the biosynthesis of mycobactins, compounds able to chelate iron, an essential cofactor for the survival of Mycobacterium tuberculosis in the host. Here, we report on the synthesis and biological evaluation of chromane-based compounds as new potential inhibitors of MbtI. Our approach successfully allowed the identification of a novel lead compound (1), endowed with a promising activity against this enzyme (IC50 = 55 µM). Molecular modeling studies were performed in order to evaluate the binding mode of 1 and rationalize the preliminary structure-activity relationships, thus providing crucial information to carry out further optimization studies.

Laparoscopic Transarterial Embolization of Type II Endoleak after Branched/Fenestrated Thoracoabdominal Aortic Aneurysm Endovascular Repair.

Type II endoleak is the most frequent procedure-related complication during endovascular aneurysm exclusion. Actually, there is little controversy in the management of type I and III endoleak, while type II endoleak still generates conflicting reports about their timing and type of treatment. Currently, the intervention is needed only in case of sac enlargement but not in case of persistent endoleak alone. We report the case of a 77-year-old man treated with a custom-made branched/fenestrated endograft for a type III thoracoabdominal aortic aneurysm. A low-flow type II endoleak was detected at the end of the intervention, and a conservative approach was adopted. The sixth month follow-up computed tomography scan demonstrated a 6-mm aneurysm sac growth that required the type II endoleak management. The endoleak nidus, situated between the inferior mesenteric artery (IMA) and left renal artery stent graft, was embolized through the IMA punctured laparoscopically. IMA origin laparoscopic clipping completed the intervention. To our knowledge, this is a unique case in the literature. Type II endoleak management should be reserved to selected patients. The combination of different techniques may offer safe and feasible treatment options in complex aneurysms treated with advanced endovascular materials.

Complicated Fenestrated Endovascular Repair of a Pararenal Aortic Aneurysm.

We report the case of a 77-year-old man treated with a custom-made fenestrated endograft for pararenal aortic aneurysm repair. Fenestrations for the superior mesenteric and both the renal arteries and augmented anterior valley and/or scallop for the celiac trunk were performed. The procedure was complicated by the superior mesenteric artery stent-graft entrapment from the endograft delivery system release wires and total dislodgement into the endograft main body. Superior mesenteric artery restenting and displaced stent-graft removal completed the intervention. Fenestrated-endograft deployment should be performed by a team familiar with the device, deployment system, and bail out solutions.

Seven-Year Approach Evolution of the Aortoiliac Occlusive Disease Endovascular Treatment.

BACKGROUND: Endovascular treatment is now considered the first-line therapy for the aortoiliac occlusive disease (AIOD). We report our experience with the total endovascular treatment of infrarenal and pararenal aortoiliac occlusions and the 7-year approach evolution. METHODS: A total of 22 patients underwent total endovascular treatment of AIOD from January 2008 to September 2014. Bare metal stents in kissing configuration were deployed in 9 cases, covered stents in kissing configuration in 9 patients and the aortic bifurcation reconstruction with the Y-guidewire configuration technique was performed in the last 4 patients. RESULTS: Technical success was 100%. Perioperative mortality rate was 4.5%. ankle-brachial index improved from 0.49 ± 0.19 to 0.96 ± 0.05 at the right side and from 0.53 ± 0.17 0.98 ± 0.04 at the left side (P < 0.01). Mean follow-up was 39.5 months (range, 5-80 months). The primary patency rate was 95.2% at 1 year and 90.5% at 3 years, and the secondary patency rate was 95.2% at 1 year and 100% at 3 years. CONCLUSIONS: Different stent types and configurations used for the aortoiliac endovascular treatment offer all the benefits of these materials for treatment on a case-by-case basis. The Y-guidewire configuration technique for the aortic bifurcation reconstruction may render the procedure more feasible. More cases and longer follow-up are necessary before the widespread use of this technique.

Aortic arch and descending thoracic aortic saccular aneurysms treatment with fenestrated endograft and chimney technique for aortic branch rescue.

We report the case of a 76-year-old man presented with three saccular aneurysms at the aortic arch and descending thoracic aorta. A two-staged hybrid approach was performed. A left common carotid-to-left subclavian artery bypass and a custom-made fenestrated endograft were used for the two proximal aneurysms. The endograft deployment was complicated by the unadverted coverage of the left common carotid artery ostium, promptly corrected with the chimney technique. The endovascular treatment was completed with the third endovascular aneurysm exclusion 5 months after the first procedure to reduce the risk of spinal cord ischemia. Yearly follow-up computed tomography scan confirmed aortic arch and descending thoracic aorta aneurysms exclusion with supra-aortic vessels, bypass, and stent patency. Endovascular repair of the aortic arch aneurysm with a fenestrated endograft is safe and feasible in selected patients. Complications may be solved with total endovascular approach. Long term follow-up remains mandatory.

Hybrid Endovascular Solutions for Supra-Aortic Vessels Extra-Anatomic Bypass Infection.

The use of extra-anatomic bypasses for the hybrid repair of thoracic aortic pathologies should consider the risk of vascular graft infection. Graft infections at cervical level are extremely rare and are associated with high mortality and morbidity rates. We report 2 cases of infected extra-anatomic bypasses for supra-aortic vessels debranching treated with a hybrid approach: re-extra-anatomical bypass with the Viabahn Open Revascularization Technique (VORTEC) in the first patient and the EndoVAC approach in the second case. Endovascular techniques may offer bail-out solutions in a hybrid fashion to treat vascular graft infection in patients considered unfeasible for the conventional surgical repair, associated with appropriate antibiotic therapy.

Hybrid treatment of symptomatic chronic isolated carotid bifurcation.

Total chronic occlusion of the common carotid artery with patent internal and external carotid arteries can induce cerebral embolism and hypoperfusion. We report a hybrid approach that was used to treat 2 patients presented with symptomatic chronic occlusion of the common carotid artery and ipsilateral internal carotid stenosis. Antegrade recanalization and retrograde stenting of the common carotid artery was performed in both patients associated to carotid bulb endarterectomy. Fresh thrombus observed in the distal common carotid stump was responsible for the embolic cerebral lesions and patients' previous symptoms. Patients remain asymptomatic at the 23rd- and 18th-month follow-up, respectively.

From aortouniiliac bifurcated to aortobisiliac trifurcated endograft for hypogastric artery preservation during EVAR.

An 81-year-old man presented with rapid enlargement of a 2-year known abdominal aortic and common iliac aneurysms. A hybrid approach to preserve both hypogastric arteries (HAs) was planned: a bifurcated endograft for the right aortoiliac axis, right femoral-to-left femoral artery bypass, and left external-to-internal iliac artery stent graft placement. Urethral stenosis requiring an epicystostomy rendered this approach not feasible. After left HA embolization, a bifurcated endograft was deployed for the abdominal aortic aneurysm exclusion. The endograft right limb was extended using a second bifurcated endograft for the ipsilateral aortoiliac axis. Surgical femoral accesses were used for the 2 bifurcated endografts and left HA embolization. Through the left brachial access, 2 stent grafts were used to preserve the right hypogastric artery revascularization. The 5-year follow-up computed tomography scan demonstrated complete aneurysm exclusion and HA patency.

The discovery of aryl-2-nitroethyl triamino pyrimidines as anti-Trypanosoma brucei agents.

Pteridine reductase 1 (PTR1) is a catalytic protein belonging to the folate metabolic pathway in Trypanosmatidic parasites. PTR1 is a known target for the medicinal chemistry development of antiparasitic agents against Trypanosomiasis and Leishmaniasis. In previous studies, new nitro derivatives were elaborated as PTR1 inhibitors. The compounds showing a diamino-pyrimidine core structure were previously developed but they showed limited efficacy. Therefore, a new class of phenyl-, heteroaryl- and benzyloxy-nitro derivatives based on the 2-nitroethyl-2,4,6-triaminopyrimidine scaffold were designed and tested. The compounds were assayed for their ability to inhibit T. brucei and L. major PTR1 enzymes and for their antiparasitic activity towards T. brucei and L. infantum parasites. To understand the structure-activity relationships of the compounds against TbPTR1, the X-ray crystallographic structure of the 2,4,6-triaminopyrimidine (TAP) was obtained and molecular modelling studies were performed. As a next step, only the most effective compounds against T. brucei were then tested against the amastigote cellular stage of T. cruzi, searching for a broad-spectrum antiprotozoal agent. An early ADME-Tox profile evaluation was performed. The early toxicity profile of this class of compounds was investigated by measuring their inhibition of hERG and five cytochrome P450 isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4), cytotoxicity towards A549 cells and mitochondrial toxicity. Pharmacokinetic studies (SNAP-PK) were performed on selected compounds using hydroxypropyl-ß-cyclodextrins (50 % w/v) to preliminarily study their plasma concentration when administered per os at a dose of 20 mg/kg. Compound 1p, showed the best pharmacodynamic and pharmacokinetic properties, can be considered a good candidate for further bioavailability and efficacy studies.

Destabilizers of the thymidylate synthase homodimer accelerate its proteasomal degradation and inhibit cancer growth.

Drugs that target human thymidylate synthase (hTS), a dimeric enzyme, are widely used in anticancer therapy. However, treatment with classical substrate-site-directed TS inhibitors induces over-expression of this protein and development of drug resistance. We thus pursued an alternative strategy that led us to the discovery of TS-dimer destabilizers. These compounds bind at the monomer-monomer interface and shift the dimerization equilibrium of both the recombinant and the intracellular protein toward the inactive monomers. A structural, spectroscopic, and kinetic investigation has provided evidence and quantitative information on the effects of the interaction of these small molecules with hTS. Focusing on the best among them, E7, we have shown that it inhibits hTS in cancer cells and accelerates its proteasomal degradation, thus causing a decrease in the enzyme intracellular level. E7 also showed a superior anticancer profile to fluorouracil in a mouse model of human pancreatic and ovarian cancer. Thus, over sixty years after the discovery of the first TS prodrug inhibitor, fluorouracil, E7 breaks the link between TS inhibition and enhanced expression in response, providing a strategy to fight drug-resistant cancers.

In Vivo Biodistribution of Respirable Solid Lipid Nanoparticles Surface-Decorated with a Mannose-Based Surfactant: A Promising Tool for Pulmonary Tuberculosis Treatment?

The active targeting to alveolar macrophages (AM) is an attractive strategy to improve the therapeutic efficacy of 'old' drugs currently used in clinical practice for the treatment of pulmonary tuberculosis. Previous studies highlighted the ability of respirable solid lipid nanoparticle assemblies (SLNas), loaded with rifampicin (RIF) and functionalized with a novel synthesized mannose-based surfactant (MS), both alone and in a blend with sodium taurocholate, to efficiently target the AM via mannose receptor-mediated mechanism. Here, we present the in vivo biodistribution of these mannosylated SLNas, in comparison with the behavior of both non-functionalized SLNas and bare RIF. SLNas biodistribution was assessed, after intratracheal instillation in mice, by whole-body real-time fluorescence imaging in living animals and RIF quantification in excised organs and plasma. Additionally, SLNas cell uptake was determined by using fluorescence microscopy on AM from bronchoalveolar lavage fluid and alveolar epithelium from lung dissections. Finally, histopathological evaluation was performed on lungs 24 h after administration. SLNas functionalized with MS alone generated the highest retention in lungs associated with a poor spreading in extra-pulmonary regions. This effect could be probably due to a greater AM phagocytosis with respect to SLNas devoid of mannose on their surface. The results obtained pointed out the unique ability of the nanoparticle surface decoration to provide a potential more efficient treatment restricted to the lungs where the primary tuberculosis infection is located.

Synthesis, activity and molecular modeling of a new series of chromones as low molecular weight protein tyrosine phosphatase inhibitors.

Protein tyrosine phosphatases (PTP) are crucial elements in eukaryotic signal transduction. Several reports suggested that the LMW-PTP family has oncogenic relevance. Moreover, LMW-PTP has been recognized as a negative regulator of insulin-mediated mitotic and metabolic signaling. Thus, inhibition of the LMW-PTP can be considered an attractive approach for the design of new therapeutic agents for the treatment of type II diabetes and for new antitumoral drugs. To date very few (and weak) inhibitors of LMW-PTP have been identified. On the basis of the reported weak activity of some flavonoids on phosphatases, we discovered a lead that originated a new class of highly active LMW-PTP inhibitors; these compounds inhibit also PTP-1B and are active in cellular assays. Docking experiments and SAR highlighted the possible binding mode of these compounds to the enzyme, putting the background for the future optimization of their inhibitory activity and selectivity towards the closely related enzyme PTP-1B.

Nanoparticles as drug delivery agents specific for CNS: in vivo biodistribution.

The pharmacological treatment of neurological disorders is often complicated by the inability of drugs to pass the blood-brain barrier. Recently we discovered that polymeric nanoparticles (NPs) made of poly(D,L-lactide-co-glycolide), surface-decorated with the peptide Gly-L-Phe-D-Thr-Gly-L-Phe-L-Leu-L-Ser(O-beta-D-glucose)-CONH2 are able to deliver, after intravenous administration, the model drug loperamide into the central nervous system (CNS). This new drug delivery agent is able to ensure a strong and long-lasting pharmacological effect, far greater than that previously observed with other nanoparticulate carriers. Here we confirmed the effectiveness of this carrier for brain targeting, comparing the effect obtained by the administration of loperamide-loaded NPs with the effect of an intracerebroventricular administration of the drug; moreover, the biodistribution of these NPs showed a localization into the CNS in a quantity about two orders of magnitude greater than that found with the other known NP drug carriers. Thus, a new kind of NPs that target the CNS with very high specificity was discovered. FROM THE CLINICAL EDITOR: This paper discusses a nanoparticle-based technique of targeted drug delivery through the blood-brain barrier. The biodistribution of these novel nanoparticles showed two orders of magnitude greater efficiency compared to other known NP drug carriers.

Newly synthesized surfactants for surface mannosylation of respirable SLN assemblies to target macrophages in tuberculosis therapy.

The present study reports about new solid lipid nanoparticle assemblies (SLNas) loaded with rifampicin (RIF) surface-decorated with novel mannose derivatives, designed for anti-tuberculosis (TB) inhaled therapy by dry powder inhaler (DPI). Mannose is considered a relevant ligand to achieve active drug targeting being mannose receptors (MR) overexpressed on membranes of infected alveolar macrophages (AM), which are the preferred site of Mycobacterium tuberculosis. Surface decoration of SLNas was obtained by means of newly synthesized functionalizing compounds used as surfactants in the preparation of carriers. SLNas were fully characterized in vitro determining size, morphology, drug loading, drug release, surface mannosylation, cytotoxicity, macrophage internalization extent and ability to bind MR, and intracellular RIF concentration. Moreover, the influence of these new surface functionalizing agents on SLNas aerodynamic performance was assessed by measuring particle respirability features using next generation impactor. SLNas exhibited suitable drug payload, in vitro release, and more efficient ability to enter macrophages (about 80%) compared to bare RIF (about 20%) and to non-functionalized SLNas (about 40%). The involvement of MR-specific binding has been demonstrated by saturating MR of J774 cells causing a decrease of RIF intracellular concentration of about 40%. Furthermore, it is noteworthy that the surface decoration of particles produced a poor cohesive powder with an adequate respirability (fine particle fraction ranging from about 30 to 50%). Therefore, the proposed SLNas may represent an encouraging opportunity in a perspective of an efficacious anti-TB inhaled therapy.

An Overview on the Potential Antimycobacterial Agents Targeting Serine/Threonine Protein Kinases from Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), still remains an urgent global health issue, mainly due to the emergence of multi-drug resistant strains. Therefore, there is a pressing need to develop novel and more efficient drugs to control the disease. In this context, targeting the pathogen virulence factors, and particularly signal mechanisms, seems to be a promising approach. An important transmembrane signaling system in Mtb is represented by receptor-type Serine/ Threonine protein kinases (STPKs). Mtb has 11 different STPKs, two of them, PknA and PknB, are essential. By contrast PknG and PknH are involved in Mtb virulence and adaptation, and are fundamental for the pathogen growth in infection models. Therefore, STPKs represent a very interesting group of pharmacological targets in M. tuberculosis. In this work, the principal inhibitors of the mycobacterial STPKs will be presented and discussed. In particular, medicinal chemistry efforts have been focused on discovering new antimycobacterial compounds, targeting three of these kinases, namely PknA, PknB and PknG. Generally, the inhibitory effect on these enzymes do not correlate with a significant antimycobacterial action in whole-cell assays. However, compounds with activity in the low micromolar range have been obtained, demonstrating that targeting Mtb STPKs could be a new promising strategy for the development of drugs to treat TB infections.

The Impact of Lipid Corona on Rifampicin Intramacrophagic Transport Using Inhaled Solid Lipid Nanoparticles Surface-Decorated with a Mannosylated Surfactant.

The mimicking of physiological conditions is crucial for the success of accurate in vitro studies. For inhaled nanoparticles, which are designed for being deposited on alveolar epithelium and taken up by macrophages, it is relevant to investigate the interactions with pulmonary surfactant lining alveoli. As a matter of fact, the formation of a lipid corona layer around the nanoparticles could modulate the cell internalization and the fate of the transported drugs. Based on this concept, the present research focused on the interactions between pulmonary surfactant and Solid Lipid Nanoparticle assemblies (SLNas), loaded with rifampicin, an anti-tuberculosis drug. SLNas were functionalized with a synthesized mannosylated surfactant, both alone and in a blend with sodium taurocholate, to achieve an active targeting to mannose receptors present on alveolar macrophages (AM). Physico-chemical properties of the mannosylated SLNas satisfied the requirements relative to suitable respirability, drug payload, and AM active targeting. Our studies have shown that a lipid corona is formed around SLNas in the presence of Curosurf, a commercial substitute of the natural pulmonary surfactant. The lipid corona promoted an additional resistance to the drug diffusion for SLNas functionalized with the mannosylated surfactant and this improved drug retention within SLNas before AM phagocytosis takes place. Moreover, lipid corona formation did not modify the role of nanoparticle mannosylation towards the specific receptors on MH-S cell membrane.

Drugs/lamellae interface influences the inner structure of double-loaded liposomes for inhaled anti-TB therapy: An in-depth small-angle neutron scattering investigation.

With the aim of developing new drug carriers for inhalation therapy, we report here an in depth investigation of the structure of multilamellar liposomes loaded with two well-established anti-tubercular (anti-TB) drugs, isoniazid (INH) and rifampicin (RIF), by means of small-angle neutron-scattering (SANS) analysis. Unloaded, single drug-loaded and co-loaded liposomes were prepared using different amounts of drugs and characterized regarding size, encapsulation efficiency and drug release. Detailed information on relevant properties of the investigated host-guest structures, namely the steric bilayer thickness, particle dispersion, number of lamellae and drug localization was studied by SANS. Results showed that RIF-liposomes were less ordered than unloaded liposomes. INH induced a change in the inter-bilayer periodical spacing, while RIF-INH co-loading stabilized the multilamellar liposome architecture, as confirmed by the increment of the drug loading capacity. These findings could be useful for the understanding of in vitro and in vivo behavior of these systems and for the design of new drug carriers, intended for inhaled therapy.

Enhancement of Benzothiazoles as Pteridine Reductase-1 Inhibitors for the Treatment of Trypanosomatidic Infections.

2-Amino-benzo[ d]thiazole was identified as a new scaffold for the development of improved pteridine reductase-1 (PTR1) inhibitors and anti-trypanosomatidic agents. Molecular docking and crystallography guided the design and synthesis of 42 new benzothiazoles. The compounds were assessed for Trypanosoma brucei and Leishmania major PTR1 inhibition and in vitro activity against T. brucei and amastigote Leishmania infantum. We identified several 2-amino-benzo[ d]thiazoles with improved enzymatic activity ( TbPTR1 IC50 = 0.35 µM; LmPTR1 IC50 = 1.9 µM) and low µM antiparasitic activity against T. brucei. The ten most active compounds against TbPTR1 were able to potentiate the antiparasitic activity of methotrexate when evaluated in combination against T. brucei, with a potentiating index between 1.2 and 2.7. The compound library was profiled for early ADME toxicity, and 2-amino- N-benzylbenzo[ d]thiazole-6-carboxamide (4c) was finally identified as a novel potent, safe, and selective anti-trypanocydal agent (EC50 = 7.0 µM). Formulation of 4c with hydroxypropyl-ß-cyclodextrin yielded good oral bioavailability, encouraging progression to in vivo studies.

SAR Studies and Biological Characterization of a Chromen-4-one Derivative as an Anti-Trypanosoma brucei Agent.

Chemical modulation of the flavonol 2-(benzo[d][1,3]dioxol-5-yl)-chromen-4-one (1), a promising anti-Trypanosomatid agent previously identified, was evaluated through a phenotypic screening approach. Herein, we have performed structure-activity relationship studies around hit compound 1. The pivaloyl derivative (13) showed significant anti-T. brucei activity (EC50 = 1.1 µM) together with a selectivity index higher than 92. The early in vitro ADME-tox properties (cytotoxicity, mitochondrial toxicity, cytochrome P450 and hERG inhibition) were determined for compound 1 and its derivatives, and these led to the identification of some liabilities. The 1,3-benzodioxole moiety in the presented compounds confers better in vivo pharmacokinetic properties than those of classical flavonols. Further studies using different delivery systems could lead to an increase of compound blood levels.