An Easy Access to Furan-Fused Polyheterocyclic Systems

Nitrostilbenes characterized by two different or differently substituted aryl moieties can be obtained from the initial ring-opening of 3-nitrobenzo[b]thiophene with amines. Such versatile building blocks couple the well-recognized double electrophilic reactivity of the nitrovinyl moiety (addition to the double bond, followed by, e.g., intramolecular replacement of the nitro group) with the possibility to exploit a conjugated system of double bonds within an electrocyclization process. Herein, nitrostilbenes are reacted with different aromatic enols provided by a double (carbon and oxygen) nucleophilicity, leading to novel, interesting naphthodihydrofurans. From these, as a viable application, aromatization and electrocyclization lead in turn to valuable polycondensed, fully aromatic O-heterocycles.     

Potential Use of Tea Tree Oil as a Disinfectant Agent against Coronaviruses: A Combined Experimental and Simulation Study

The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.     

Engineered Ferritin with Eu3+ as a Bright Nanovector: A Photoluminescence Study

Ferritin nanoparticles play many important roles in theranostic and bioengineering applications and have been successfully used as nanovectors for the targeted delivery of drugs due to their ability to specifically bind the transferrin receptor (TfR1, or CD71). They can be either genetically or chemically modified for encapsulating therapeutics or probes in their inner cavity. Here, we analyzed a new engineered ferritin nanoparticle, made of the H chain mouse ferritin (HFt) fused with a specific lanthanide binding tag (LBT). The HFt-LBT has one high affinity lanthanide binding site per each of the 24 subunits and a tryptophane residue within the tag that acts as an antenna able to transfer the energy to the lanthanide ions via a LRET process. In this study, among lanthanides, we selected europium for its red emission that allows to reduce overlap with tissue auto-fluorescence. Steady state emission measurements and time-resolved emission spectroscopy have been employed to investigate the interaction between the HFt-LBT and the Eu³⁺ ions. This allowed us to identify the Eu³⁺ energy states involved in the process and to pave the way for the future use of HFt-LBT Eu³⁺ complex in theranostics.     

A Sharp Inequality on the Exponentiation of Functions on the Sphere

In this paper we show a new inequality that generalizes to the unit sphere the Lebedev-Milin inequality of the exponentiation of functions on the unit circle. It may also be regarded as the counterpart on the sphere of the second inequality in the Szegö limit theorem on the Toeplitz determinants on the circle. On the other hand, this inequality is also a variant of several classical inequalities of Moser-Trudinger type on the sphere. The inequality incorporates the deviation of the center of mass from the origin into the optimal inequality of Aubin for functions with mass centered at the origin, and improves Onofri's inequality with the contribution of the shifting of the mass center explicitly expressed. © 2021 Wiley Periodicals LLC.     

The Role of Cytochrome P450 AbyV in the Final Stages of Abyssomicin C Biosynthesis

Abyssomicin C and its atropisomer are potent inhibitors of bacterial folate metabolism. They possess complex polycyclic structures, and their biosynthesis has been shown to involve several unusual enzymatic transformations. Using a combination of synthesis and in vitro assays we reveal that AbyV, a cytochrome P450 enzyme from the aby gene cluster, catalyses a key late-stage epoxidation required for the installation of the characteristic ether-bridged core of abyssomicin C. The X-ray crystal structure of AbyV has been determined, which in combination with molecular dynamics simulations provides a structural framework for our functional data. This work demonstrates the power of combining selective carbon-13 labelling with NMR spectroscopy as a sensitive tool to interrogate enzyme-catalysed reactions in vitro with no need for purification.     

Polycaprolactone based biodegradable polyurethanes

Two series of segmented polyurethanes were prepared with systematic variation in soft and hard segment length. The soft segment was constituted by polycaprolactone (PCL) blocks of molecular masses 530 or 2000 and the hard segment (HS) by urethane blocks, in a concentration that varied from 12% to 44% in weight of the whole polyurethane. Morphological analyses indicated that the amount of crystallinity of copolymers was strongly dependent on the PCL molar mass and hard segment content. The copolymers with longer PCL soft segments (Mn=2000) were semicrystalline, but those with shorter PCL segment (Mn=530) were unable to crystallize. The primary factor affectingthe biodegradability of copolymers as evaluated by Sturm tests was the extent of the phase separation, and that the segmental blending of the less biodegradable polyurethane (HS) blocks with PCL in the amorphous phase had a critical unfavorable consequence, which may be attributed to the size of the accessible area by microorganisms.