Influence of H-bond competitors on the solvent-dependent structures of an octaurea-calix[4]tube

A novel octaurea-calix[4]tube (UC4T) has been synthesized in three steps from the original Beer's p-tert-butylcalix[4]tube ionophore. In a polar solvent (DMSO-d6), UC4T rapidly interconverts between two identical conformations with C2v symmetry for the two calix[4]arene subunits. However, in a less polar solvent mixture (CDCl3/DMSO-d6, 98 : 2), UC4T adopts a highly distorted asymmetric structure, which hinders the formation of typical tetraurea calix[4]arene capsular assemblies. The complexation of potassium (or barium) cations inside the dioxyethylene ionophoric binding site of UC4T triggers a C2v to C4v symmetry rearrangement of the two calix[4]arene subunits. This rearrangement leads to the formation of a transient capsular dimeric species observed in solution upon the addition of KI or BaCl2·2H2O to a solution (CDCl3/DMSO-d6, 98 : 2) of the macrocycle. X-ray studies confirm UC4T's ability to adopt different asymmetric conformations, depending on its interactions with solvent molecules. Two distinct crystal forms (α and β) of UC4T have been obtained, each displaying divergent calix[4]arene subunits with pinched-cone conformations. These conformations exhibit distinctive head-to-tail (α) or head-to-head/tail-to-tail (β) orientations of the ureido groups, which are involved in hydrogen bonding with solvent molecules. Notably, the pseudo-capsular 1D supramolecular polymeric arrays observed in the β form of UC4T assemble to create large parallel solvent channels.

IDH-wild type glioblastomas featuring at least 30% giant cells are characterized by frequent RB1 and NF1 alterations and hypermutation

Giant cell glioblastoma (GC-GBM) is a rare variant of IDH-wt GBM histologically characterized by the presence of numerous multinucleated giant cells and molecularly considered a hybrid between IDH-wt and IDH-mutant GBM. The lack of an objective definition, specifying the percentage of giant cells required for this diagnosis, may account for the absence of a definite molecular profile of this variant. This study aimed to clarify the molecular landscape of GC-GBM, exploring the mutations and copy number variations of 458 cancer-related genes, tumor mutational burden (TMB), and microsatellite instability (MSI) in 39 GBMs dichotomized into having 30-49% (15 cases) or ≥ 50% (24 cases) GCs. The type and prevalence of the genetic alterations in this series was not associated with the GCs content (< 50% or ≥ 50%). Most cases (82% and 51.2%) had impairment in TP53/MDM2 and PTEN/PI3K pathways, but a high proportion also featured TERT promoter mutations (61.5%) and RB1 (25.6%) or NF1 (25.6%) alterations. EGFR amplification was detected in 18% cases in association with a shorter overall survival (P = 0.004). Sixteen (41%) cases had a TMB > 10 mut/Mb, including two (5%) that harbored MSI and one with a POLE mutation. The frequency of RB1 and NF1 alterations and TMB counts were significantly higher compared to 567 IDH wild type (P < 0.0001; P = 0.0003; P < 0.0001) and 26 IDH-mutant (P < 0.0001; P = 0.0227; P < 0.0001) GBMs in the TCGA PanCancer Atlas cohort. These findings demonstrate that the molecular landscape of GBMs with at least 30% giant cells is dominated by the impairment of TP53/MDM2 and PTEN/PI3K pathways, and additionally characterized by frequent RB1 alterations and hypermutation and by EGFR amplification in more aggressive cases. The high frequency of hypermutated cases suggests that GC-GBMs might be candidates for immune check-point inhibitors clinical trials.

Shedding Light on the Chemistry and the Properties of Münchnone Functionalized Graphene

Münchnones are mesoionic oxazolium 5-oxides with azomethine ylide characteristics that provide pyrrole derivatives by a 1,3-dipolar cycloaddition (1,3-DC) reaction with acetylenic dipolarophiles. Their reactivity was widely exploited for the synthesis of small molecules, but it was not yet investigated for the functionalization of graphene-based materials. Herein, we report our results on the preparation of münchnone functionalized graphene via cycloaddition reactions, followed by the spontaneous loss of carbon dioxide and its further chemical modification to silver/nisin nanocomposites to confer biological properties. A direct functionalization of graphite flakes into few-layers graphene decorated with pyrrole rings on the layer edge was achieved. The success of functionalization was confirmed by micro-Raman and X-ray photoelectron spectroscopies, scanning transmission electron microscopy, and thermogravimetric analysis. The 1,3-DC reactions of münchnone dipole with graphene have been investigated using density functional theory to model graphene. Finally, we explored the reactivity and the processability of münchnone functionalized graphene to produce enriched nano biomaterials endowed with antimicrobial properties.

8-Hydroxyquinoline-2-Carboxylic Acid as Possible Molybdophore: A Multi-Technique Approach to Define Its Chemical Speciation, Coordination and Sequestering Ability in Aqueous Solution

8-hydroxyquinoline-2-carboxylic acid (8-HQA) has been found in high concentrations (0.5–5.0 mmol·dm⁻³) in the gut of Noctuid larvae (and in a few other lepidopterans), in which it is proposed to act as a siderophore. Since it is known that many natural siderophores are also involved in the uptake and metabolism of other essential elements than iron, this study reports some results on the investigation of 8-HQA interactions with molybdate (MoO₄²⁻, i.e., the main molybdenum form in aqueous environments), in order to understand the possible role of this ligand as molybdophore. A multi-technique approach has been adopted, in order to derive a comprehensive set of information necessary to assess the chemical speciation of the 8-HQA/MoO₄²⁻ system, as well as the coordination behavior and the sequestering ability of 8-HQA towards molybdate. Chemical speciation studies have been performed in KCl_(aq) at I = 0.2 mol·dm⁻³ and T = 298.15 K by ISE-H⁺ (glass electrode) potentiometric and UV/Vis spectrophotometric titrations. CV (Cyclic Voltammetry), DP-ASV (Differential Pulse-Anodic Stripping Voltammetry), ESI-MS experiments and quantum mechanical calculations have been also performed to derive information about the nature and possible structure of species formed. These results are also compared with those reported for the 8-HQA/Fe³⁺ system in terms of chemical speciation and sequestering ability of 8-HQA.

Functionalized polyhedral oligosilsesquioxane (POSS) based composites for bone tissue engineering: synthesis, computational and biological studies

Functionalized polyhedral oligosilsesquioxanes (POSS) containing an isoxazolidine nucleus have been synthesized by microwave assisted 1,3-dipolar cycloaddition of N-methyl-C-alkoxycarbonyl nitrone 1 with POSS containing olefin moieties. The results of cycloaddition processes were rationalized by computational studies at the DFT level. The covalent conjugation of chitosan with the cycloadduct 3a leads to composite material CS-POSS 7 which was gelified using genipin as cross linking agent. The suitability of the system for bone tissue engineering purposes was evaluated by in vitro drug release studies using ketoprofen as a model drug and cytotoxicity assays performed on human fetal osteoblastic cells. The preliminary biological tests showed the lack of cytotoxicity of the hybrid material and suggest its potential role in bone tissue engineering applications.

Simulated human digestion of N1-aryl-2-arylthioacetamidobenzimidazoles and their activity against Herpes-simplex virus 1 in vitro

Drug performance in the gastrointestinal tract (GIT) plays a crucial role in determining release and absorption. In the present work, we assessed the in vitro digestion of two synthetic N1-aryl-2-arylthioacetamidobenzimidazoles (NAABs), NAAB-496 and NAAB-503, using bio-relevant models of the human stomach and small intestine. The activity of NAAB-496 and NAAB-503 against herpes simplex virus (HSV-1) replication was also investigated. NAAB-496 was resistant to pepsin in the gastric environment, with a virtual 100% recovery, which decreased to 43.2% in the small intestine. NAAB-503 was sensitive to pepsin, with 65.7% degradation after 120 min gastric phase. ¹H Nuclear magnetic resonance (NMR) post in vitro digestion highlighted an alteration of NAAB-496 after the gastric phase, whereas NAAB-503 appeared comparable to the original spectral data. Both NAAB-496 and NAAB-503 revealed some antiviral activity anti-HSV-1. The 50% effective concentration (EC₅₀) of the compounds was 0.058 mg/mL for NAAB-496 and 0.066 for NAAB-503. Future studies will evaluate the behavior of NAAB-496 within pharmaceutical formulations.