Metabolic Investigation and Auxiliary Enzyme Modelization of the Pyrrocidine Pathway Allow Rationalization of Paracyclophane-Decahydrofluorene Formation

Fungal paracyclophane-decahydrofluorene-containing natural products are complex polycyclic metabolites derived from similar hybrid PKS-NRPS pathways. Herein we studied the biosynthesis of pyrrocidines, one representative of this family, by gene inactivation in the producer Sarocladium zeae coupled to thorough metabolic analysis and molecular modeling of key enzymes. We characterized nine pyrrocidines and analogues as well as in mutants a variety of accumulating metabolites with new structures including rare cis-decalin, cytochalasan, and fused 6/15/5 macrocycles. This diversity highlights the extraordinary plasticity of the pyrrocidine biosynthetic gene cluster. From accumulating metabolites, we delineated the scenario of pyrrocidine biosynthesis. The ring A of the decahydrofluorene is installed by PrcB, a membrane-bound cyclizing isomerase, on a PKS-NRPS-derived pyrrolidone precursor. Docking experiments in PrcB allowed us to characterize the active site suggesting a mechanism triggered by arginine-mediated deprotonation at the terminal methyl of the substrate. Next, two integral membrane proteins, PrcD and PrcE, each predicted as a four-helix bundle, perform hydroxylation of the pyrrolidone ring and paracyclophane formation, respectively. Modelization of PrcE highlights a topological homology with vitamin K oxido-reductase and the presence of a disulfide bond. Our results suggest a previously unsuspected coupling mechanism via a transient loss of aromaticity of tyrosine residue to form the strained paracyclophane motif. Finally, the lipocalin-like protein PrcX drives the exo-cycloaddition yielding ring B and C of the decahydrofluorene to afford pyrrocidine A, which is transformed by a reductase PrcI to form pyrrocidine B. These insights will greatly facilitate the microbial production of pyrrocidine analogues by synthetic biology.

Aurantoside L, a New Tetramic Acid Glycoside with Anti-Leishmanial Activity Isolated from the Marine Sponge Siliquariaspongia japonica

A new tetramic acid glycoside, aurantoside L (1), was isolated from the sponge Siliquariaspongia japonica collected at Tsushima Is., Nagasaki Prefecture, Japan. The structure of aurantoside L (1) composed of a tetramic acid bearing a chlorinated polyene system and a trisaccharide part was elucidated using spectral analysis. Aurantoside L (1) showed anti-parasitic activity against L. amazonensis with an IC50 value of 0.74 µM.

Miscibility studies on carboxymethyl chitosan and poly(N-vinylpyrrolidone) mixtures

The production of polymer mixtures is a widely used method to improve polymer performance, as such mixtures can combine advantageous properties from each component. In this study, mixtures based on carboxymethyl chitosan (CMCh) and poly(N-vinylpyrrolidone) (PVP) were characterized using steady shear measurements, viscometry, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. Viscometry and steady shear studies were performed on solutions of the native polymers and their mixtures with various weight proportions (80/20, 50/50, and 20/80%w/w). The rheological tests revealed that the apparent viscosity of solutions of CMCh/PVP mixtures was higher than that of the native polymer solutions. The rheological data showed that CMCh solutions and their mixtures were typical pseudoplastic liquids, which could be accurately described by the Cross and power law models. Viscometric parameters were determined using the method proposed by Garcia et al., which indicated good miscibility between CMCh and PVP in aqueous solution. Furthermore, the morphology, structure, and thermal properties of CMCh films changed when PVP was added. The obtained analytical data showed the formation of stable mixtures of CMCh and PVP, with a high miscibility ratio between these polymers, through intermolecular interactions between the polymer chains.

RIPK1 Is Cleaved by 3C Protease of Rhinovirus A and B Strains and Minor and Major Groups

Rhinoviruses (RV), like many other viruses, modulate programmed cell death to their own advantage. The viral protease, 3C has an integral role in the modulation, and we have shown that RVA-16 3C protease cleaves Receptor-interacting protein kinase-1 (RIPK1), a key host factor that modulates various cell death and cell survival pathways. In the current study, we have investigated whether this cleavage is conserved across selected RV strains. RIPK1 was cleaved in cells infected with strains representing diversity across phylogenetic groups (A and B) and receptor usage (major and minor groups). The cleavage was abrogated in the presence of the specific 3C protease inhibitor, Rupintrivir. Interestingly, there appears to be involvement of another protease (maybe 2A protease) in RIPK1 cleavage in strains belonging to genotype B. Our data show that 3C protease from diverse RV strains cleaves RIPK1, highlighting the importance of the cleavage to the RV lifecycle.

Synthesis and Bioactivity of Ancorinoside B, a Marine Diglycosyl Tetramic Acid

The sponge metabolite ancorinoside B was prepared for the first time in 16 steps and 4% yield. It features a β-d-galactopyranosyl-(1→4)-β-d-glucuronic acid tethered to a d-aspartic acid-derived tetramic acid. Key steps were the synthesis of a fully protected d-lactose derived thioglycoside, its attachment to a C20-aldehyde spacer, functionalization of the latter with a terminal N-(β-ketoacyl)-d-aspartate, and a basic Dieckmann cyclization to close the pyrrolidin-2,4-dione ring with concomitant global deprotection. Ancorinoside B exhibited multiple biological effects of medicinal interest. It inhibited the secretion of the cancer metastasis-relevant matrix metalloproteinases MMP-2 and MMP-9, and also the growth of Staphylococcus aureus biofilms by ca 87% when applied at concentrations as low as 0.5 µg/mL. This concentration is far below its MIC of ca 67 µg/mL and thus unlikely to induce bacterial resistance. It also led to a 67% dispersion of preformed S. aureus biofilms when applied at a concentration of ca 2 µg/mL. Ancorinoside B might thus be an interesting candidate for the control of the general hospital, catheter, or joint protheses infections.

Effect of N-Vinyl-2-Pyrrolidone (NVP), a Bromodomain-Binding Small Chemical, on Osteoblast and Osteoclast Differentiation and Its Potential Application for Bone Regeneration

The human skeleton is a dynamic and remarkably organized organ system that provides mechanical support and performs a variety of additional functions. Bone tissue undergoes constant remodeling; an essential process to adapt architecture/resistance to growth and mechanical needs, but also to repair fractures and micro-damages. Despite bone's ability to heal spontaneously, certain situations require an additional stimulation of bone regeneration, such as non-union fractures or after tumor resection. Among the growth factors used to increase bone regeneration, bone morphogenetic protein-2 (BMP2) is certainly the best described and studied. If clinically used in high quantities, BMP2 is associated with various adverse events, including fibrosis, overshooting bone formation, induction of inflammation and swelling. In previous studies, we have shown that it was possible to reduce BMP2 doses significantly, by increasing the response and sensitivity to it with small molecules called "BMP2 enhancers". In the present study, we investigated the effect of N-Vinyl-2-pyrrolidone (NVP) on osteoblast and osteoclast differentiation in vitro and guided bone regeneration in vivo. We showed that NVP increases BMP2-induced osteoblast differentiation and decreases RANKL-induced osteoclast differentiation in a dose-dependent manner. Moreover, in a rabbit calvarial defect model, the histomorphometric analysis revealed that bony bridging and bony regenerated area achieved with NVP-loaded poly (lactic-co-glycolic acid (PLGA) membranes were significantly higher compared to unloaded membranes. Taken together, our results suggest that NVP sensitizes BMP2-dependent pathways, enhances BMP2 effect, and inhibits osteoclast differentiation. Thus, NVP could prove useful as "osteopromotive substance" in situations where a high rate of bone regeneration is required, and in the management of bone diseases associated with excessive bone resorption, like osteoporosis.

Pan-3C Protease Inhibitor Rupintrivir Binds SARS-CoV-2 Main Protease in a Unique Binding Mode

Rupintrivir targets the 3C cysteine proteases of the picornaviridae family, which includes rhinoviruses and enteroviruses that cause a range of human diseases. Despite being a pan-3C protease inhibitor, rupintrivir activity is extremely weak against the homologous 3C-like protease of SARS-CoV-2. In this study, the crystal structures of rupintrivir were determined bound to enterovirus 68 (EV68) 3C protease and the 3C-like main protease (Mpro) from SARS-CoV-2. While the EV68 3C protease-rupintrivir structure was similar to previously determined complexes with other picornavirus 3C proteases, rupintrivir bound in a unique conformation to the active site of SARS-CoV-2 Mpro splitting the catalytic cysteine and histidine residues. This bifurcation of the catalytic dyad may provide a novel approach for inhibiting cysteine proteases.

Bespoke 3D-Printed Polydrug Implants Created via Microstructural Control of Oligomers

Controlling the microstructure of materials by means of phase separation is a versatile tool for optimizing material properties. Phase separation has been exploited to fabricate intricate microstructures in many fields including cell biology, tissue engineering, optics, and electronics. The aim of this study was to use phase separation to tailor the spatial location of drugs and thereby generate release profiles of drug payload over periods ranging from 1 week to months by exploiting different mechanisms: polymer degradation, polymer diluent dissolution, and control of microstructure. To achieve this, we used drop-on-demand inkjet three-dimensional (3D) printing. We predicted the microstructure resulting from phase separation using high-throughput screening combined with a model based on the Flory-Huggins interaction parameter and were able to show that drug release from 3D-printed objects can be predicted from observations based on single drops of mixtures. We demonstrated for the first time that inkjet 3D printing yields controllable phase separation using picoliter droplets of blended photoreactive oligomers/monomers. This new understanding gives us hierarchical compositional control, from droplet to device, allowing release to be "dialled up" without manipulation of device geometry. We exemplify this approach by fabricating a biodegradable, long-term, multiactive drug delivery subdermal implant ("polyimplant") for combination therapy and personalized treatment of coronary heart disease. This is an important advance for implants that need to be delivered by cannula, where the shape is highly constrained and thus the usual geometrical freedoms associated with 3D printing cannot be easily exploited, which brings a hitherto unseen level of understanding to emergent material properties of 3D printing.

Five Tetramic Acid Derivatives Isolated from the Iranian Fungus Colpoma quercinum CCTU A372

Submerged mycelial cultures of the ascomycete Colpoma quercinum CCTU A372 were found to produce five previously undescribed tetramic acids, for which we propose the trivial names colposetins A-C (1-3) and colpomenoic acids A and B (4 and 5), along with the known compounds penicillide (6) and monodictyphenone (7). The planar structures of 1-5 were determined by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and extensive 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Their absolute configurations were determined by the combination of electronic circular dischroism (ECD) analysis, J-based configurational analysis, and a rotating-frame Overhauser effect spectroscopy (ROESY) experiment. Colposetin B displayed weak antimicrobial activity against Bacillus subtilis and Mucor hiemalis (MIC 67 µg/mL).

On the Transition from a Biomimetic Molecular Switch to a Rotary Molecular Motor

The experimental investigation of the unidirectional motion characterizing the photoisomerization of single-molecule rotary motors requires accessible lab prototypes featuring an electronic circular dichroism (ECD) signal that is sensitive to the geometrical and electronic changes occurring during an ultrafast reactive process. Here we report a combined experimental/computational study of a candidate obtained via the asymmetrization of a light-driven biomimetic molecular switch. We show that the achieved motor has an ECD band that is remarkably sensitive to the isomerization motion, and it is therefore suitable for time-resolved ECD studies. However, we also find that, unexpectedly, the synthesized motor isomerizes on a time scale longer than the subpicosecond time measured for the achiral parent, a result that points to alternative candidates conserving a high reaction speed.

Structure-Activity Relationships for the Marine Natural Product Sintokamides: Androgen Receptor N-Terminus Antagonists of Interest for Treatment of Metastatic Castration-Resistant Prostate Cancer

Synthetic analogues of the marine natural product sintokamides have been prepared in order to investigate the structure-activity relationships for the androgen receptor N-terminal domain (AR NTD) antagonist activity of the sintokamide scaffold. An in vitro LNCaP cell-based transcriptional activity assay with an androgen-driven luciferase (Luc) reporter was used to monitor the potency of analogues. The data have shown that the chlorine atoms on the leucine side chains are essential for potent activity. Analogues missing the nonchlorinated methyl groups of the leucine side chains (C-1 and C-17) are just as active and in some cases more active than the natural products. Analogues with the natural R configuration at C-10 and the unnatural R configuration at C-4 are most potent. Replacing the natural propionamide N-terminus cap with the more sterically hindered pivaloylamide N-terminus cap leads to enhanced potency. The tetramic acid fragment and the methyl ether on the tetramic acid fragment are essential for activity. The SAR optimized analogue 76 is more selective, easier to synthesize, more potent, and presumed to be more resistant to proteolysis than the natural sintokamides.

Is PF-00835231 a Pan-SARS-CoV-2 Mpro Inhibitor? A Comparative Study

The COVID-19 outbreak continues to spread worldwide at a rapid rate. Currently, the absence of any effective antiviral treatment is the major concern for the global population. The reports of the occurrence of various point mutations within the important therapeutic target protein of SARS-CoV-2 has elevated the problem. The SARS-CoV-2 main protease (Mpro) is a major therapeutic target for new antiviral designs. In this study, the efficacy of PF-00835231 was investigated (a Mpro inhibitor under clinical trials) against the Mpro and their reported mutants. Various in silico approaches were used to investigate and compare the efficacy of PF-00835231 and five drugs previously documented to inhibit the Mpro. Our study shows that PF-00835231 is not only effective against the wild type but demonstrates a high affinity against the studied mutants as well.

Structure and State of Water in Branched N-Vinylpyrrolidone Copolymers as Carriers of a Hydrophilic Biologically Active Compound

Hydrated copolymers of N-vinylpyrrolidone (VP) with triethylene glycol dimethacrylate as a promising platform for biologically active compounds (BAC) were investigated by different physical chemical methods (dynamic light scattering, infrared spectroscopy, thermal gravimetric analysis, and differential scanning calorimetry) and the quantum chemical modeling of water coordination by the copolymers in a solution. According to the quantum chemical simulation, one to two water molecules can coordinate on one O-atom of the lactam ring of VP units in the copolymer. Besides the usual terminal coordination, the water molecule can form bridges to bind two adjacent C=O groups of the lactam rings of VP units. In addition to the first hydration shell, the formation of a second one is also possible due to the chain addition of water molecules, and its structure depends on a mutual orientation of C=O groups. We showed that N,N-dimethylbiguanidine hydrochloride (metformin) as a frontline drug for the treatment of type 2 diabetes mellitus can be associated in aqueous solutions with free and hydrated C=O groups of the lactam rings of VP units in studied copolymers. Based on the characteristics of the H-bonds, we believe that the level of the copolymer hydration does not affect the behavior and biological activity of this drug, but the binding of metformin with the amphiphilic copolymer will delight in the penetration of a hydrophilic drug across a cell membrane to increase its bioavailability.

Anti-Inflammatory Effects of Analogues of N-Acyl Homoserine Lactones on Eukaryotic Cells

BACKGROUND

Since acyl-homoserine lactone (AHL) profiling has been described in the gut of healthy subjects and patients with inflammatory bowel disease (IBD), the potential effects of these molecules on host cells have raised interest in the medical community. In particular, natural AHLs such as the 3-oxo-C12-HSL exhibit anti-inflammatory properties. Our study aimed at finding stable 3-oxo-C12-HSL-derived analogues with improved anti-inflammatory effects on epithelial and immune cells.

METHODS

We first studied the stability and biological properties of the natural 3-oxo-C12-HSL on eukaryotic cells and a bacterial reporter strain. We then constructed and screened a library of 22 AHL-derived molecules. Anti-inflammatory effects were assessed by cytokine release in an epithelial cell model, Caco-2, and a murine macrophage cell line, RAW264.7, (respectively, IL-8 and IL-6) upon exposure to the molecule and after appropriate stimulation (respectively, TNF-α 50 ng/mL and IFN-γ 50 ng/mL, and LPS 10 ng/mL and IFN-γ 20 U/mL).

RESULTS

We found two molecules of interest with amplified anti-inflammatory effects on mammalian cells without bacterial-activating properties in the reporter strain. The molecules furthermore showed improved stability in biological medium compared to the native 3-oxo-C12-HSL.

CONCLUSIONS

We provide new bio-inspired AHL analogues with strong anti-inflammatory properties that will need further study from a therapeutic perspective.

Gamma radiation-induced preparation of chitosan-acrylic acid-1-vinyl-2-vinylpyrrolidone/multiwalled carbon nanotubes composite for removal of 152+154Eu, 60Co and 134Cs radionuclides

Removal behaviors of ^152+154Eu, ⁶⁰Co, and ¹³⁴Cs radionuclides onto Chitosan-acrylic acid-1-vinyl-2-vinylpyrrolidone/oxidized multi-walled carbon nanotubes (CTS-AA-VP/o-MWCNTs) composite has been investigated by batch adsorption technique. CTS-AA-VP/o-MWCNTs composite has been synthesized by copolymerization of acrylic acid (AA) and 1-vinyl-2-vinylpyrrolidone (VP) onto the surface of chitosan/oxidized multi-walled carbon nanotubes (CTS/o-MWCNTs) using gamma radiation. SEM, TGA, and FTIR were applied to characterize the morphology, thermal stability, and structure of the composite. The composite shows high removal capacity of 321.77, 369.91, and 456.46 mg/g towards ^152+154Eu, ⁶⁰Co, and ¹³⁴Cs radionuclides, respectively.

Morphology and water flux of produced cellulose acetate membranes reinforced by the design of experiments (DOE)

Cellulose acetate (CA) ultrafiltration membranes were successfully prepared using the non-solvent induced phase separation (NIPS) methodology. This technique is used to produce porous membranes for a large variety of applications. However, the formation of a dense skin during the process reduces membrane pure water flux (PWF). To overcome this issue, three parameters were investigated: CA/NMP (N-methyl-2-pyrrolidone) ratio in the casting solution, acetone (Ac)/water (W) ratio in the precipitation bath composition (PBC) and support material (glass/polyethylene). The effect of each factor on the mean pore size, water contact angle, porosity and PWF was supported by Taguchi design. The increase in the CA/NMP ratio reduced mean pore size and porosity. In contrast, there was an increase in porosity and hydrophilicity with increasing Ac/W ratio. The maximum value of PWF was obtained for membranes prepared using a PE support. ANOVA showed that most, but not all, factors had significant effects on the parameters measured.

N-Ethyl-2-Pyrrolidinone-Substituted Flavan-3-Ols with Anti-inflammatory Activity in Lipopolysaccharide-Stimulated Macrophages Are Storage-Related Marker Compounds for Green Tea

Fresh green tea (GT) is commonly considered to have better sensory flavor and higher commercial value than long-term-stored GT; however, the chemical variations during storage are unclear. In this study, the chemical profiles of stored GT were surveyed among time-series samples from 0 to 19 months using a nontargeted metabolomics method. Seven N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs) increased from 0.022 ± 0.019 to 3.212 ± 0.057 mg/g within 19 months (correlation coefficients with storage duration ranging from 0.936 to 0.965), and they were the most significantly increased compounds among the 127 identified compounds. Two representative EPSFs (R-EGCG-cThea and S-EGCG-cThea) possess potential anti-inflammatory properties by suppressing the expression, phosphorylation, and nuclear translocation of nuclear factor kappa-B (NF-κB) p65 in lipopolysaccharide-stimulated macrophages based on western blotting and immunofluorescence results. In conclusion, EPSFs were found to be marker compounds for stored GT and showed potential anti-inflammatory activity by regulating the NF-κB signaling pathway.

Reusable fibrous adsorbent prepared via Co-radiation induced graft polymerization for iodine adsorption

Volatile iodine released from nuclear power plant reactors is radiological hazard to environment and human's health because of their high fission yield and environmental mobility. The complexity of nuclear waste management motivated the development of solid-phase adsorbents. Herein, co-radiation induced graft polymerization (CRIGP) was employed in the graft polymerization of N-vinyl-2-pyrrolidone (NVP) onto polyethylene-coated polypropylene skin-core (PE/PP) fibers using electron beam (EB) irradiation. This work provides a one-step green synthetic approach to prepare iodine fibrous adsorbents without any chemical initiators or large amount of organic solvent. The original and modified PE/PP fibers were characterized by fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and scanning electron microscopy (SEM) to demonstrate the grafting of NVP onto the PE/PP fibers. The capacity of iodine absorbed by the PE/PP-g-PNVP fibers was 1237.8 mg/g after 180 min. Meanwhile, absorbents can be regenerated efficiently by two different means of ethanol elution and heating at 120 °C, respectively. Within 10 min, 94.17% and 90.12% of the iodine can be released from the PE/PP-g-PNVP fibers with these two methods, respectively. The adsorbent exhibited a long service life of at least ten adsorption-desorption cycles, suggesting that PE/PP-g-PNVP fibers might be a promising adsorbent for volatile iodine adsorption from fission products in nuclear power plant reactors.

N-Butylpyrrolidinone for Solid-Phase Peptide Synthesis is Environmentally Friendlier and Synthetically Better than DMF

Solid-phase peptide synthesis (SPPS) is the method of choice for the preparation of peptides in both laboratory scale and large production. Although the methodology has been improved during the last decades allowing the achievement of long peptides and challenging sequences in good yields and purities, the process was not revised from an environmental point of view. One of the main problems in this regard is the large amount of solvents used, and therefore the tons of generated waste. Moreover, the solvent of choice for the SPPS is N,N-dimethylformamide (DMF), which is considered as reprotoxic; thus, there is an urgent necessity to replace it with safer solvents. The DMF substitution by a green solvent is not a trivial task, because it should solubilize all the reagents and byproducts involved in the process, and, in addition to facilitating the coupling of the different amino acids, it should not favor the formation of side-reactions compared with DMF. Herein, it was demonstrated that the use of the green solvent N-butylpyrrolidinone (NBP) as a replacement of DMF was beneficial in two well-documented side reactions in peptide synthesis, racemization and aspartimide formation. The use of NBP rendered a lower or equal level of racemization in the amino acids more prone to this side reaction than DMF, whilst the aspartimide formation was clearly lower when NBP was used as solvent. Our findings demonstrate that the use of a green solvent does not hamper the synthetic process and could even improve it, making it environmentally friendlier and synthetically better.

Exploring with [18F]UCB-H the in vivo Variations in SV2A Expression through the Kainic Acid Rat Model of Temporal Lobe Epilepsy

PURPOSE

The main purpose of this study was to understand how the positron emission tomography (PET) measure of the synaptic vesicle 2A (SV2A) protein varies in vivo during the development of temporal lobe epilepsy (TLE) in the kainic acid rat model.

PROCEDURES

Twenty Sprague Dawley male rats were administered with multiple systemic doses of saline (control group, n = 5) or kainic acid (5 mg/kg/injection, epileptic group, n = 15). Both groups were scanned at the four phases of TLE (early, latent, transition, and chronic phase) with the [18F]UCB-H PET radiotracer and T2-structural magnetic resonance imaging. At the end of the scans (3 months post-status epilepticus), rats were monitored for 7 days with electroencephalography for the detection of spontaneous electrographic seizures. Finally, the immunofluorescence staining for SV2A expression was performed.

RESULTS

Control rats presented a significant increase in [18F]UCB-H binding at the last two scans, compared with the first ones (p < 0.001). This increase existed but was lower in epileptic animals, producing significant group differences in all the phases of the disease (p < 0.028). Furthermore, the quantification of the SV2A expression in vivo with the [18F]UCB-H radiotracer or ex vivo with immunofluorescence led to equivalent results, with a positive correlation between both.

CONCLUSIONS

Even if further studies in humans are required, the ability to detect a progressive decrease in SV2A expression during the development of temporal lobe epilepsy supports the use of [18F]UCB-H as a useful tool to differentiate, in vivo, between healthy and epileptic animals along with the development of the epileptic disease.

Structure of the HRV-C 3C-Rupintrivir Complex Provides New Insights for Inhibitor Design

Human rhinoviruses (HRVs) are the predominant infectious agents for the common cold worldwide. The HRV-C species cause severe illnesses in children and are closely related to acute exacerbations of asthma. 3C protease, a highly conserved enzyme, cleaves the viral polyprotein during replication and assists the virus in escaping the host immune system. These key roles make 3C protease an important drug target. A few structures of 3Cs complexed with an irreversible inhibitor rupintrivir have been determined. These structures shed light on the determinants of drug specificity. Here we describe the structures of HRV-C15 3C in free and inhibitor-bound forms. The volume-decreased S1' subsite and half-closed S2 subsite, which were thought to be unique features of enterovirus A 3C proteases, appear in the HRV-C 3C protease. Rupintrivir assumes an "intermediate" conformation in the complex, which might open up additional avenues for the design of potent antiviral inhibitors. Analysis of the features of the three-dimensional structures and the amino acid sequences of 3C proteases suggest new applications for existing drugs.

A Phototheranostic Strategy to Continuously Deliver Singlet Oxygen in the Dark and Hypoxic Tumor Microenvironment

Continuous irradiation during photodynamic therapy (PDT) inevitably induces tumor hypoxia, thereby weakening the PDT effect. In PDT-induced hypoxia, providing singlet oxygen from stored chemical energy may enhance the cell-killing effect and boost the therapeutic effect. Herein, we present a phototheranostic (DPPTPE@PEG-Py NPs) prepared by using a 2-pyridone-based diblock polymer (PEG-Py) to encapsulate a semiconducting, heavy-atom-free pyrrolopyrrolidone-tetraphenylethylene (DPPTPE) with high singlet-oxygen-generation ability both in dichloromethane and water. The PEG-Py can trap the 1 O2 generated from DPPTPE under laser irradiation and form a stable intermediate of endoperoxide, which can then release 1 O2 in the dark, hypoxic tumor microenvironment. Furthermore, fluorescence-imaging-guided phototherapy demonstrates that this phototheranostic could completely inhibit tumor growth with the help of laser irradiation.

Synthesis and structure-affinity relationship of chlorinated pyrrolidinone-bearing benzenesulfonamides as human carbonic anhydrase inhibitors

A novel set of pyrrolidinone-based chlorinated benzenesulfonamide derivatives were synthesized and investigated for their binding affinity and selectivity against recombinant human carbonic anhydrases I-XIV using fluorescent thermal shift, p-nitrophenyl acetate hydrolysis and stopped-flow enzymatic inhibition assays. The hydrazones 10-22 prepared from 1-(2-chloro-4-sulfamoylphenyl)-5-oxopyrrolidine-3-carboxylic acid exhibited low nanomolar affinity against cancer-related CA IX (Kd in the range of 5.0-37 nM). Compounds with triazole or oxadiazole groups attached directly to pyrrolidinone moiety bound all CAs weaker than compounds with more flexible tail groups. Chloro group at the meta position of benzenesulfonamide derivatives increased affinity to all CAs as compared with binding data for nonchlorinated compounds. The compounds have a potential for further development of CA inhibitors with higher selectivity for a particular CA isozyme.

Natural pseurotins and analogs thereof inhibit activation of B-cells and differentiation into the plasma cells

BACKGROUND

The frequency of allergic diseases is constantly rising. Dysregulated production of isotype E immunoglobulins is one of the key factors behind allergic reactions and its modulation is therefore an important target for pharmacological intervention. Natural products of the pseurotin family were reported to be inhibitors of IgE production in B-cells. Mechanistic details underlying these effects are however not well understood.

PURPOSE

In the present study, we synthesized new analogs of natural pseurotins and extensively investigated their inhibitory effects on activation, proliferation and differentiation of B-cells, as well as on the production of IgE.

STUDY DESIGN

Effects of two natural pseurotins (pseurotins A and D) and a collection of fully synthetic pseurotin analogs were studied on mouse B-cells stimulated by the combination of IL-4 and E. coli lipopolysaccharide. The IgE production was determined along with cell viability and cell proliferation. The phosphorylation of selected members of the STAT transcription factor family was subsequently investigated. Finally, the in vivo effect of pseurotin D on the ovalbumin-induced delayed type hypersensitivity response was tested in mice.

RESULTS

We discovered that several fully synthetic pseurotin analogs were able to decrease the production of IgE in stimulated B-cells with potency comparable to that of pseurotins A and D. We found that the two natural pseurotins and the active synthetic analogs inhibited the phosphorylation of STAT3, STAT5 and STAT6 proteins in stimulated B-cells, resulting in the inhibition of B-cell proliferation and differentiation into the plasma cells. In vivo, pseurotin D decreased ovalbumin-induced foot pad edema.

CONCLUSION

Our results advance the current mechanistic understanding of the pseurotin-induced inhibition of IgE production in B-cells by linking the effect to STAT signaling, and associated modulation of B-cell proliferation and differentiation. Together with our finding that structurally simpler pseurotin analogs were able to reproduce the effects of natural pseurotins, the presented work has implications for the future research on these secondary metabolites in the context of allergic diseases.

Pyrrolidone-based polymers capable of reversible iodine capture for reuse in antibacterial applications

Numerous emerging and re-emerging advanced materials have been successful in capturing iodine pollutants that pose an unprecedented global challenge to public health. However, little attention has been paid to the reutilization of the captured iodine. Herein, we report on a pyrrolidone-based polymer capable of reversible iodine capture for reutilization in antibacterial applications. The pyrrolidone-based polymer poly(N-vinyl-2-pyrrolidone-co-vinyl acetate), denoted as P(VAc-NVP), was synthesized facilely via a one-step radical copolymerization strategy, and the synthesis was regulated by step-by-step optimization, specifically by tuning the feed ratio of NVP to VAc. The as-synthesized P(VAc-NVP) copolymer functioned as an adsorbent for iodine in various solutions, including water/ethanol, cyclohexane, and petroleum ether, in addition to having the special capability of releasing iodine in the presence of starch or bacteria. This opens up a new horizon for its functional practical use as a flexible adsorbent to capture iodine for safe disposal. Interestingly, the P(VAc-NVP) copolymer, after adsorbing iodine, showed antibacterial ability against pathogenic bacteria, including Staphylococcus aureus and Escherichia coli, when a series of simulated and practical antibacterial assays were conducted. It is believed that this proposed strategy based on the synergism of iodine capture and antibacterial use should have great potential for environmental remediation and public healthcare.

Hybrid Polyketides from a Hydractinia-Associated Cladosporium sphaerospermum SW67 and Their Putative Biosynthetic Origin

Five hybrid polyketides (1a, 1b, and 2–4) containing tetramic acid core including a new hybrid polyketide, cladosin L (1), were isolated from the marine fungus Cladosporium sphaerospermum SW67, which was isolated from the marine hydroid polyp of Hydractinia echinata. The hybrid polyketides were isolated as a pair of interconverting geometric isomers. The structure of 1 was determined based on 1D and 2D NMR spectroscopic and HR-ESIMS analyses. Its absolute configuration was established by quantum chemical electronic circular dichroism (ECD) calculations and modified Mosher’s method. Tetramic acid-containing compounds are reported to be derived from a hybrid PKS-NRPS, which was also proved by analyzing our ¹³C-labeling data. We investigated whether compounds 1–4 could prevent cell damage induced by cisplatin, a platinum-based anticancer drug, in LLC-PK1 cells. Co-treatment with 2 and 3 ameliorated the damage of LLC-PK1 cells induced by 25 μM of cisplatin. In particular, the effect of compound 2 at 100 μM (cell viability, 90.68 ± 0.81%) was similar to the recovered cell viability of 88.23 ± 0.25% with 500 μM N-acetylcysteine (NAC), a positive control.

Tunable hydrogels for controlling phenotypic cancer cell states to model breast cancer dormancy and reactivation

During metastasis, disseminated tumor cells (DTCs) from the primary tumor infiltrate secondary organs and reside there for varying lengths of time prior to forming new tumors. The time delay between infiltration and active proliferation, known as dormancy, mediates the length of the latency period. DTCs may undergo one of four fates post-infiltration: death, cellular dormancy, dormant micrometastasis, or invasive growth which, is in part, mediated by extracellular matrix (ECM) properties. Recapitulation of these cell states using engineered hydrogels could facilitate the systematic and controlled investigation of the mechanisms by which ECM properties influence DTC fate. Toward this goal, we implemented a set of sixteen hydrogels with systematic variations in chemical (ligand (RGDS) density and enzymatic degradability) and mechanical (elasticity, swelling, mesh size) properties to investigate their influence on the fate of encapsulated metastatic breast cancer cells, MDA-MB-231. Cell viability, apoptosis, proliferation, metabolic activity, and morphological measurements were acquired at five-day intervals over fifteen days in culture. Analysis of the phenotypic metrics indicated the presence of four different cell states that were classified as: (1) high growth, (2) moderate growth, (3) single cell, restricted survival, dormancy, or (4) balanced dormancy. Correlating hydrogel properties with the resultant cancer cell state indicated that ligand (RGDS) density and enzymatic degradability likely had the most influence on cell fate. Furthermore, we demonstrate the ability to reactivate cells from the single cell, dormant state to the high growth state through a dynamic increase in ligand (RGDS) density after forty days in culture. This tunable engineered hydrogel platform offers insight into matrix properties regulating tumor dormancy, and the dormancy-proliferation switch, and may provide future translational benefits toward development of anti-dormancy therapeutic strategies.

ANOVA Design for the Optimization of TiO2 Coating on Polyether Sulfone Membranes

There have been developments in the optimization of polyethersulfone (PES) membranes, to provide antifouling and mechanically stable surfaces which are vital to water purification applications. There is a variety of approaches to prepare nanocomposite PES membranes. However, an optimized condition for making such membranes is in high demand. Using experimental design and statistical analysis (one-half fractional factorial design), this study investigates the effect of different parameters featured in the fabrication of membranes, as well as on the performance of a nanocomposite PES/TiO₂ membrane. The optimized parameters obtained in this study are: exposure time of 60 s, immersion time above 10 h, glycerol time of 4 h, and a nonsolvent volumetric ratio (isopropanol/water) of 30/70 for PES and dimethylacetamide (PES-DMAc) membrane and 70/30 for PES and N-methyl-2-pyrrolidone (PES-NMP) membrane. A comparison of the contributory factors for different templating agents along with a nanocomposite membrane control revealed that F127 triblock copolymer resulted in an excellent antifouling membrane with a higher bovine serum albumin rejection and flux recovery of 83.33%.

The 3S Enantiomer Drives Enolase Inhibitory Activity in SF2312 and Its Analogues

We recently reported that SF2312 ((1,5-dihydroxy-2-oxopyrrolidin-3-yl)phosphonic acid), a phosphonate antibiotic with a previously unknown mode of action, is a potent inhibitor of the glycolytic enzyme, Enolase. SF2312 can only be synthesized as a racemic-diastereomeric mixture. However, co-crystal structures with Enolase 2 (ENO2) have consistently shown that only the (3S,5S)-enantiomer binds to the active site. The acidity of the alpha proton at C-3, which deprotonates under mildly alkaline conditions, results in racemization; thus while the separation of four enantiomeric intermediates was achieved via chiral High Performance Liquid Chromatography (HPLC) of the fully protected intermediate, deprotection inevitably nullified enantiopurity. To prevent epimerization of the C-3, we designed and synthesized MethylSF2312, ((1,5-dihydroxy-3-methyl-2-oxopyrrolidin-3-yl)phosphonic acid), which contains a fully-substituted C-3 alpha carbon. As a racemic-diastereomeric mixture, MethylSF2312 is equipotent to SF2312 in enzymatic and cellular systems against Enolase. Chiral HPLC separation of a protected MethylSF2312 precursor resulted in the efficient separation of the four enantiomers. After deprotection and inevitable re-equilibration of the anomeric C-5, (3S)-MethylSF2312 was up to 2000-fold more potent than (3R)-MethylSF2312 in an isolated enzymatic assay. This observation strongly correlates with biological activity in both human cancer cells and bacteria for the 3S enantiomer of SF2312. Novel X-ray structures of human ENO2 with chiral and racemic MethylSF2312 show that only (3S,5S)-enantiomer occupies the active site. Enolase inhibition is thus a direct result of binding by the (3S,5S)-enantiomer of MethylSF2312. Concurrent with these results for MethylSF2312, we contend that the (3S,5S)-SF2312 is the single active enantiomer of inhibitor SF2312.

In vitro blood compatibility and in vitro cytotoxicity of amphiphilic poly-N-vinylpyrrolidone nanoparticles

This study focused on defining the in vitro behavior of amphiphilic poly-N-vinylpyrrolidone (Amph-PVP) nanoparticles toward whole blood, blood plasma and blood cells in order to assess nanoparticle blood compatibility. In addition, possible effects on endothelium cell growth/viability were evaluated. The Amph-PVP nanoparticles were formed via self-assembling in aqueous media and composed of a hydrophobic alkyl core and a hydrophilic PVP outer shell. Their blood compatibility was evaluated by investigating their effect on red blood cells (RBCs) or erythrocytes, white blood cells (WBCs) or leukocytes, platelets (PLTs) and on complement system activation. Our results clearly demonstrate that the Amph-PVP nanoparticles are stable in presence of blood serum, have no significant effects on the function of RBCs, WBCs, PLTs and complement system activation. The Amph-PVP nanoparticles did not show considerable hemolytic or inflammatory effect, neither influence on platelet aggregation, coagulation process, or complement activation at the tested concentration range of 0.05-0.5 mg/ml. The Amph-PVP nanoparticles did not exhibit any significant effect on HMEC-1 microvascular skin endothelial cells' growth in in vitro experiments. The excellent blood compatibility of the Amph-PVP nanoparticles and the lack of effect on endothelium cell growth/viability represent a crucial feature dictating their further study as novel drug delivery systems.

Ants Do Not Traverse the Silk of Adult Female Nephila clavipes (Linnaeus) Webs

Many organisms use chemicals to deter enemies. Some spiders can modify the composition of their silk to deter predators from climbing onto their webs. The Malaysian golden orb-weaver Nephila antipodiana (Walckenaer) produces silk containing an alkaloid (2-pyrrolidinone) that functions as a defense against ant invasion-ants avoid silk containing this chemical. In the present study, we test the generality of ants' silk avoidance behavior in the field. We introduced three ant species to the orb webs of Nephila clavipes (Linnaeus) in the tropical rainforest of La Selva, Costa Rica. We found that predatory army ants (Eciton burchellii Westwood) as well as non-predatory leaf-cutting ants (Atta cephalotes Linnaeus and Acromyrmex volcanus Wheeler) avoided adult N. clavipes silk, suggesting that an additional species within genus Nephila may possess ant-deterring silk. Our field assay also suggests that silk avoidance behavior is found in multiple ant species.

Ag nanoparticles inhibit the growth of the bryophyte, Physcomitrella patens

The wide use of Ag nanoparticles (Ag NPs) as antimicrobial agents has resulted in a massive release of Ag NPs into environment, such as water and soil. As bryophytes live ubiquitously in water and soil, their tolerance and response to Ag NPs could be employed as an indicator for the harm of Ag NPs to the environment. Herein, we report the study on the physiological and biochemical responses of bryophytes to Ag NPs with different surface coatings at the gametophyte stages: protonema and leafy gametophyte, by using Physcomitrella patens as a model system. We found that Ag NPs, including AgNPs-B (Ag NPs without surface coating), AgNPs-PVP (Ag NPs coated with poly (N-vinyl-2-pyrrolidone)) and AgNPs-Cit (Ag NPs coated with citrate), were toxic to P. patens in terms of growth and development of the gametophyte. The toxicity was closely related to the concentration and surface coating of Ag NPs, and the growth stage of P. patens. The protonema was more sensitive to Ag NPs than the leafy gametophyte. Ag NPs inhibited the growth of the protonema following the trend of AgNPs-B > AgNPs-Cit > AgNPs-PVP. Ag NPs changed the thylakoid and chlorophyll contents, but did not affect the contents of essential elements in the protonema. At the leafy gametophyte stage, Ag NPs inhibited the growth of P. patens following a different order: AgNPs-Cit > AgNPs-B ≈ AgNPs-PVP. Ag NPs decreased the chlorophyll b content and disturbed the balance of some important essential elements in the leafy gametophytes. Both the dissolved fraction of Ag NPs and Ag NPs per se contributed to the toxicity. This study for the first time reveals the effects of Ag NPs on bryophytes at different growth stages, which calls for more attention to the nanoecotoxicology of Ag NPs.

A New Chemoenzymatic Synthesis of the Chiral Key Intermediate of the Antiepileptic Brivaracetam

Brivaracetam is a new anticonvulsant compound, recently approved as an antiepileptic drug. This drug substance presents a 4-substituted pyrrolidone structure: the (4R)-configuration of the stereocenter present on the heterocyclic ring is the main target of the synthesis. The described method allows to prepare the suitable optically pure 2-substituted primary alcohol by means of a Pseudomonas fluorescens lipase-catalyzed transesterification. The obtained (2R)-alcohol was easily transformed into the (3R)-3-propylbutyrolactone, an advanced intermediate of brivaracetam. The described synthetic pathway is completed with the chromatographic methods and the NMR analyses necessary to establish the chemical and the optical purity of the intermediates and of the final lactone.

Flavoalkaloids with a Pyrrolidinone Ring from Chinese Ancient Cultivated Tea Xi-Gui

Chinese Xi-Gui tea is one ancient cultivated variety of Camellia sinensis var. assamica. At present, it is used for producing expensive and elite tea in China. Five new flavoalkaloids, (-)-6-(5''' S)- N-ethyl-2-pyrrolidinone-epicatechin-3- O-gallate (ester-type catechins pyrrolidinone E, etc-pyrrolidinone E, 1), (-)-6-(5''' R)- N-ethyl-2-pyrrolidinone-epicatechin-3- O-gallate (etc-pyrrolidinone F, 2) (-)-8-(5''' S)- N-ethyl-2-pyrrolidinone-epicatechin-3- O-gallate (etc-pyrrolidinone G, 3a), (-)-8-(5''' S)- N-ethyl-2-pyrrolidinone-catechin-3- O-gallate (etc-pyrrolidinone I, 4a), (-)-8-(5''' R)- N-ethyl-2-pyrrolidinone-catechin-3- O-gallate (etc-pyrrolidinone J, 4b), and one new naturally occurring natural product (-)-8-(5''' R)- N-ethyl-2-pyrrolidinone-epicatechin-3- O-gallate (etc-pyrrolidinone H, 3b) together with the known flavoalkaloids etc-pyrrolidinones A-D (5, 6, 7a, and 7b) were detected and isolated from Xi-Gui green tea. Their structures were identified by comprehensive NMR spectroscopic analyses. Absolute configurations of 1-3 were established by comparison of the CD analyses with epicatechin-3- O-gallate (ECG). Compounds 1-4 were evaluated for their protection against high glucose induced cell senescence on human umbilical vein endothelia cells (HUVECs) and showed significant protection effects ( p < 0.01) at both 1.0 and 10 μM. A discussion on the possible evolution of tea plants divergent from related food plants on the basis of phytochemical view is also provided.

Aniline-Tetramic Acids from the Deep-Sea-Derived Fungus Cladosporium sphaerospermum L3P3 Cultured with the HDAC Inhibitor SAHA

Four new tetramic acids, cladosins H-K (1-4), and a related known compound, cladodionen (5), were isolated from the culture of the Mariana Trench (depth 6562 m) sediment-derived fungus Cladosporium sphaerospermum L3P3 treated with the histone deacetylase inhibitor SAHA (suberanilohydroxamic acid). Interestingly, compounds 1-5 existed as equilibrium E/ Z mixtures and 1-4 were the first cases of tetramic acids containing aniline moieties. Their structures including absolute configurations were elucidated through a combination of NMR, MS, and Mosher's method, together with the consideration of biogenetic origins. Incubation experiments of exogenous aniline and N-phenyloctanamide revealed that the aniline moiety in cladosins H-K (1-4) is probably derived from the degradation of SAHA, indicating that the well-known histone deacetylase inhibitor SAHA could be metabolized by L3P3 and provide aniline as a precursor for biotransformation of chemically reactive polyketides. The cytotoxicity of 1-5 was evaluated against the PC-3, MGC-803, SH-SY5Y, HCT-116, K562, and HL-60 cell lines, and compound 2 showed promising cytotoxicity against the HL-60 cell line with an IC₅₀ value of 2.8 μM.

Metabolomics Investigation Reveals That 8-C N-Ethyl-2-pyrrolidinone-Substituted Flavan-3-ols Are Potential Marker Compounds of Stored White Teas

White teas of different stored ages have varied flavor, bioactivity, and commercial value. In this study, a liquid chromatography-mass spectrometry-based metabolomics investigation revealed that there are distinct differences among the compound patterns of Baihaoyinzhen (BHYZ) and Baimudan (BMD) white teas with various storage durations. The levels of flavan-3-ols, procyanidins, theasinensins, theaflavins, flavonol- O-glycosides, flavone- C-glycosides, and most of the amino acids were reduced after long-term (>4 years) storage. More importantly, 8-C N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs), including seven novel compounds discovered in white teas for the first time, were formed from theanine and flavan-3-ols during storage, and their contents were positively correlated with the storage duration. These findings were further confirmed by the linearly increasing formation of EPSFs in reaction solution and BMD white teas stored in an environment-controlled cabinet. In conclusion, EPSFs were detected in white teas for the first time and were discovered as marker compounds and potential indicators for long-term storage of white tea.

C-8 N-Ethyl-2-pyrrolidinone-Substituted Flavan-3-ols from the Leaves of Camellia sinensis var. pubilimba

Camellia sinensis var. pubilimba, one variety of the genus Camellia sect. Thea (Theaceae), has been used for producing green tea mainly by the local people of its growing areas of Guangxi province, China. Forty compounds, including eight C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (1-8) and their substituted unit N-ethyl-5-hydroxy-2-pyrrolidinone (9), four flavan-3-ol monomers (10-13) and one dimer (14), nine flavonoids (15-23), three hydrolyzable tannins (24-26), two lignans (27-28), 11 simple phenolics (29-39), and caffeine (40), were first isolated and identified from the leaves. Their structures were determined by detailed spectroscopic analysis and comparison with the literature data and authentic samples. Both 1 and 4 were obtained as a mixture of the N-ethyl-2-pyrrolidinone C-5 enantiomers (1a and 1b and 4a and 4b), respectively, while the resolution of another three pairs of enantiomers (2 and 3, 5 and 6, and 7 and 8) was achieved. Among them, 1b is a new compound whose NMR data together with its enantiomer (1a) were reported for the first time, while 2 and 3 are two new natural products. Most of the isolates exhibited significant antioxidant activities, stronger than ascorbic acid and trolox, while parts of the isolates, particularly C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols, showed obvious inhibitory effects on acetylcholinesterase (AChE). The results indicated that C. sinensis var. pubilimba is a valuable plant resource for tea production.

Off-line solid phase extraction and liquid chromatography-tandem mass spectrometry method for the quantitation of brivaracetam acid metabolites: Method validation and application to in vitro metabolism assays

Brivaracetam (BRV) is a new high affinity synaptic vesicle protein 2A ligand recently approved for adults with partial-onset seizures. As a support to in vitro metabolism assays, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method coupled to off-line solid phase extraction (SPE) was developed to quantify BRV acid metabolites, that is, BRV-AC (carboxylic derivative derived from BRV hydrolysis) and BRV-OHAC (corresponding to hydroxylated BRV-AC). The method was validated for various incubates (liver and kidney tissue homogenates and blood, all from humans) and applied to in vitro metabolism assays. The analytes were isolated from buffered samples using ISOLUTE C8 96-well SPE plates. Chromatographic separation was achieved on a Waters Atlantis T3 C18 analytical column (2.1 mm × 50 mm, 5 μm) with detection accomplished using a Waters Premier tandem mass spectrometer in positive ion electrospray and multiple reaction monitoring (MRM) mode. The standard curves, which ranged from 1.00 to 200 ng/mL for BRV-AC, BRV-OHAC, were fitted to a 1/x² weighted linear regression model. The intra-assay precision and inter-assay precision (expressed as coefficient of variation -%CV) were <8.5%, and the assay accuracy (deviation - %Dev) was within ±7.1% for the different matrices. This accurate, precise, and selective SPE/LC-MS/MS method has been successfully applied to in vitro assays aimed at characterizing the kinetics of BRV hydrolysis. BRV was found to be a better substrate for hydrolysis than its hydroxylated metabolite BRV-OH. BRV hydrolysis was detected in blood, liver and kidneys, demonstrating the broad distribution of the enzyme catalyzing the reaction.

Synthesis of polyaniline (PANI) and functionalized polyaniline (F-PANI) nanoparticles with controlled size by solvent displacement method. Application in fluorescence detection and bacteria killing by photothermal effect

Polyaniline nanoparticles (PANI-NPs) were easily obtained applying the solvent displacement method by using N-methylpyrrolidone (NMP) as good solvent and water as poor solvent. Different polymers such as polyvinylpyrrolidone (PVP), chondroitin sulfate (ChS), polyvinyl alcohol (PVA), and polyacrylic acid (PAA) were used as stabilizers. Dynamic light scattering and scanning electron microscopy corroborated the size and morphology of the formed NPs. It was demonstrated that the size of nanoparticles could be controlled by setting the concentration of PANI in NMP, the NMP to water ratio, and the stabilizer's nature. The functionalization and fluorescence of NPs were checked by spectroscopic techniques. Since polyaniline show only weak intrinsic luminescence, fluorescent groups were linked to the polyaniline chains prior to the nanoparticle formation using a linker. Polyaniline chains were functionalized by nucleophilic addition of cysteamine trough the thiol group thereby incorporating pendant primary aliphatic amine groups to the polyaniline backbone. Then, dansyl chloride (DNS-Cl), which could act as an extrinsic chromophore, was conjugated to the amine pendant groups. Later, the functionalized polyaniline was used to produce nanoparticles by solvent displacement. The optical and functional properties of fluorescent nanoparticles (F-PANI-NPs) were determined. F-PANI-NPs in the conductive state (pH < 4) are able to absorb near infrared radiation (NIR) creating a photothermal effect in an aqueous medium. Thus, multifunctional nanoparticles are obtained. The application of NIR on a F-PANI-NPs dispersion in contact with Pseudomonas aeruginosa causes bacterial death. Therefore, the F-PANI-NPs could be tracked and applied to inhibit different diseases caused by pathogenic microorganisms and resistant to antibiotics as well as a new disinfection method to surgical materials.

Introduction of sacrificial bonds to hydrogels to increase defect tolerance during suturing of multilayer vascular grafts

Small-caliber vascular grafts used in coronary artery bypass procedures typically fail due to the development of intimal hyperplasia or thrombosis. Our laboratory has developed a multilayered vascular graft with an electrospun polyurethane outer layer with improved compliance matching and a hydrogel inner layer that is both thromboresistant and promotes endothelialization. Initial in vivo studies showed that hydrogel particulates were dislodged from the hydrogel layer of the grafts during suturing. To address this problem, we developed and characterized a new hydrogel formulation that resists damage during suturing. Introduction of sacrificial, hydrogen bonds to poly(ethylene glycol)-based hydrogels via co-polymerization with n-vinyl pyrrolidone (NVP) increased the fracture energy as determined by single edge notch testing. This enhanced defect tolerance resulted in a hydrogel layer that was resistant to suture-induced damage with no dislodged particles observed. Importantly, the incorporation of NVP did not affect the thromboresistance, bioactivity, or biostability of the hydrogel layer. In addition to eliminating complications due to hydrogel particle generation in our multilayer graft design, this defect tolerant hydrogel formulation has broad potential use in many cardiovascular and soft tissue applications.

STATEMENT OF SIGNIFICANCE

Small-caliber vascular grafts used in coronary artery bypass procedures typically fail due to development of intimal hyperplasia or thrombosis. Our laboratory has developed a multilayered vascular graft with an electrospun polyurethane outer layer with improved compliance matching and a hydrogel inner layer that is both thromboresistant and promotes endothelialization. However, hydrogel particulates were dislodged from the hydrogel layer during suturing in vivo. This work describes a hydrogel formulation based on poly(ethylene glycol) that is resistant to suture-induced damage. The introduction of sacrificial, hydrogen bonds by co-polymerization with n-vinyl pyrrolidone (NVP) resulted in an increase fracture energy without affecting the thromboresistance, bioactivity, or biostability. This defect-tolerant hydrogel formulation and the methodology to assess hydrogel defect tolerance has broad potential use in cardiovascular and soft tissue applications.

High-strength N-methyl-2-pyrrolidone-containing process wastewater treatment using sequencing batch reactor and membrane bioreactor: A feasibility study

N-methyl-2-pyrrolidone (NMP) is widely used as a solvent in polymeric membrane fabrication process, its elimination from the process wastewater (normally at a high concentration > 1000 mg/L) prior to discharge is essential because of environmental concern. This study investigated the feasibility of treating high-strength NMP-containing process wastewater in a sequencing batch reactor (SBR; i.e., batch feeding and intermittent aerobic/anoxic condition) and a membrane bioreactor (MBR; i.e., continuous feeding and aeration), respectively. The results showed that the SBR with the acclimated sludge was capable of removing >90% of dissolved organic carbon (DOC) and almost 98% of NMP within 2 h. In contrast, the MBR with the acclimated sludge showed a decreasing NMP removal efficiency from 100% to 40% over 15-day operation. The HPLC and LC-MS/MS analytical results showed that NMP degradation in SBR and MBR could undergo different pathways. This may be attributed to the dissimilar bacterial community compositions in the SBR and MBR as identified by 16s rRNA gene sequencing analysis. Interestingly, the NMP-degrading capability of the activated sludge derived from MBR could be recovered to >98% after they were operated at the SBR mode (batch feeding mode with intermittent aerobic/anoxic condition). This study reveals that SBR is probably a more feasible process to treat high-strength NMP-containing wastewater, but residual NMP metabolites in the SBR effluent need to be post-treated by an oxidation or adsorption process in order to achieve zero-discharge of toxic chemicals.

Total Synthesis of the Marine Alkaloid Discoipyrrole C via the MoOPH-Mediated Oxidation of a 2,3,5-Trisubstituted Pyrrole

A total synthesis of the marine alkaloid discoipyrrole C (3) is described. In the pivotal step, the 2,3,5-trisubstituted pyrrole 19 was treated with MoOPH in the presence of MeOH, and the resulting methoxylated 1,2-dihydro-3H-pyrrol-3-one 20 subjected to reaction with potassium carbonate in MeOH then trifluoroacetic acid and H₂O. This gave a mixture of target 3 and its dehydration product, and the structure of the former compound was confirmed by single-crystal X-ray analysis.

Molecularly Targeted Cancer Combination Therapy with Near-Infrared Photoimmunotherapy and Near-Infrared Photorelease with Duocarmycin-Antibody Conjugate

Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that uses an antibody-photoabsorber conjugate (APC). However, the effect of NIR-PIT can be enhanced when combined with other therapies. NIR photocaging groups, based on the heptamethine cyanine scaffold, have been developed to release bioactive molecules near targets after exposure to light. Here, we investigated the combination of NIR-PIT using panitumumab-IR700 (pan-IR700) and the NIR-releasing compound, CyEt-panitumumab-duocarmycin (CyEt-Pan-Duo). Both pan-IR700 and CyEt-Pan-Duo showed specific binding to the EGFR-expressing MDAMB468 cell line in vitro In in vivo studies, additional injection of CyEt-Pan-Duo immediately after NIR light exposure resulted in high tumor accumulation and high tumor-background ratio. To evaluate the effects of combination therapy in vivo, tumor-bearing mice were separated into 4 groups: (i) control, (ii NIR-PIT, (iii) NIR-release, (iv) combination of NIR-PIT and NIR-release. Tumor growth was significantly inhibited in all treatment groups compared with the control group (P < 0.05), and significantly prolonged survival was achieved (P < 0.05 vs. control). The greatest therapeutic effect was shown with NIR-PIT and NIR-release combination therapy. In conclusion, combination therapy of NIR-PIT and NIR-release enhanced the therapeutic effects compared with either NIR-PIT or NIR-release therapy alone. Mol Cancer Ther; 17(3); 661-70. ©2017 AACR.

Direct Synthesis of 2-Formylpyrrolidines, 2-Pyrrolidinones and 2-Dihydrofuranones via Aerobic Copper-Catalyzed Aminooxygenation and Dioxygenation of 4-Pentenylsulfonamides and 4-Pentenylalcohols

A new method for the direct conversion of 4-pentenylsulfonamides to 2-formylpyrrolidines and a 2-ketopyrrolidine has been developed. This transformation occurs via aerobic copper-catalyzed alkene aminooxygenation where molecular oxygen serves as both oxidant and oxygen source. The 2-formylpyrrolidines can further undergo oxidative carbon-carbon bond cleavage in situ upon addition of DABCO, providing 2-pyrrolidinones. These transformations have been demonstrated for a range of 4-pentenylsulfonamides. 4-Pentenylalcohols also undergo oxidative cyclization to form γ-lactones predominantly. The reaction is chemoselective, oxidizing one alkene in the presence of others, and is compatible with several functional groups. Application of these reactions to the formal syntheses of baclofen and (+)-monomorine was demonstrated.

A New N-methoxypyridone from the Co-Cultivation of Hawaiian Endophytic Fungi Camporesia sambuci FT1061 and Epicoccum sorghinum FT1062

A new N-methoxypyridone analog (1), together with four known compounds, was isolated from the co-culture of Hawaiian endophytic fungi Camporesia sambuci FT1061 and Epicoccum sorghinum FT1062. The structure of the new compound was elucidated as 11S-hydroxy-1-methoxyfusaricide (1) by extensive spectroscopic analysis and comparison with the literature. The absolute configuration of 1 was determined by comparison with the experimental and calculated ECD spectra. The absolute configuration of compound 3 was investigated and renamed as (+)-epipyridone by comparison of the optical rotation and CD spectrum with those of 1. The other known compounds were identified as epicoccarine B (2), D8646-2-6 (4), and iso-D8646-2-6 (5). Compounds 4 and 5 showed modest inhibitory activity towards pathogenic fungi. Epicoccarine B (2) inhibited A2780 and TK-10 with an IC₅₀ value of 22 μM.

Structure of the Enterovirus 71 3C Protease in Complex with NK-1.8k and Indications for the Development of Antienterovirus Protease Inhibitor

Hand-foot-and-mouth disease (HFMD), caused by enterovirus, is a threat to public health worldwide. To date, enterovirus 71 (EV71) has been one of the major causative agents of HFMD in the Pacific-Asia region, and outbreaks with EV71 cause millions of infections. However, no drug is currently available for clinical therapeutics. In our previous works, we developed a set of protease inhibitors (PIs) targeting the EV71 3C protease (3Cpro). Among these are NK-1.8k and NK-1.9k, which have various active groups and high potencies and selectivities. In the study described here, we determined the structures of the PI NK-1.8k in complex with wild-type (WT) and drug-resistant EV71 3Cpro Comparison of these structures with the structure of unliganded EV71 3Cpro and its complex with AG7088 indicated that the mutation of N69 to a serine residue destabilized the S2 pocket. Thus, the mutation influenced the cleavage activity of EV71 3Cpro and the inhibitory activity of NK-1.8k in an in vitro protease assay and highlighted that site 69 is an additional key site for PI design. More information for the optimization of the P1' to P4 groups of PIs was also obtained from these structures. Together with the results of our previous works, these in-depth results elucidate the inhibitory mechanism of PIs and shed light to develop PIs for the clinical treatment of infections caused by EV71 and other enteroviruses.

High-density lipoprotein sensor based on molecularly imprinted polymer

Decreased blood level of high-density lipoprotein (HDL) is one of the essential criteria in diagnosing metabolic syndrome associated with the development of atherosclerosis and coronary heart disease. Herein, we report the synthesis of a molecularly imprinted polymer (MIP) that selectively binds HDL, namely, HDL-MIP, and thus serves as an artificial, biomimetic sensor layer. The optimized polymer contains methacrylic acid and N-vinylpyrrolidone in the ratio of 2:3, cross-linked with ethylene glycol dimethacrylate. On 10 MHz dual electrode quartz crystal microbalances (QCM), such HDL-MIP revealed dynamic detection range toward HDL standards in the clinically relevant ranges of 2–250 mg/dL HDL cholesterol (HDL-C) in 10 mM phosphate-buffered saline (PBS, pH = 7.4) without significant interference: low-density lipoprotein (LDL) yields 5% of the HDL signal, and both very-low-density lipoprotein (VLDL) and human serum albumin (HSA) yield 0%. The sensor reveals recovery rates between 94 and 104% at 95% confidence interval with precision of 2.3–7.7% and shows appreciable correlation (R² = 0.97) with enzymatic colorimetric assay, the standard in clinical tests. In contrast to the latter, it achieves rapid results (10 min) during one-step analysis without the need for sample preparation.

Graphical Abstract

Biodegradable "Smart" Polyphosphazenes with Intrinsic Multifunctionality as Intracellular Protein Delivery Vehicles

A series of biodegradable drug delivery polymers with intrinsic multifunctionality have been designed and synthesized utilizing a polyphosphazene macromolecular engineering approach. Novel water-soluble polymers, which contain carboxylic acid and pyrrolidone moieties attached to an inorganic phosphorus-nitrogen backbone, were characterized by a suite of physicochemical methods to confirm their structure, composition, and molecular sizes. All synthesized polyphosphazenes displayed composition-dependent hydrolytic degradability in aqueous solutions at neutral pH. Their formulations were stable at lower temperatures, potentially indicating adequate shelf life, but were characterized by accelerated degradation kinetics at elevated temperatures, including 37 °C. It was found that synthesized polyphosphazenes are capable of environmentally triggered self-assembly to produce nanoparticles with narrow polydispersity in the size range of 150-700 nm. Protein loading capacity of copolymers has been validated via their ability to noncovalently bind avidin without altering biological functionality. Acid-induced membrane-disruptive activity of polyphosphazenes has been established with an onset corresponding to the endosomal pH range and being dependent on polymer composition. The synthesized polyphosphazenes facilitated cell-surface interactions followed by time-dependent, vesicular-mediated, and saturable internalization of a model protein cargo into cancer cells, demonstrating the potential for intracellular delivery.

Structural Revision and Biosynthesis of the Fungal Phytotoxins Phyllostictines A and B

The structure of the fungal phytotoxins known as the phyllostictines has been revised to a series of bicyclic 3-methylene tetramic acids. Genome sequencing of the producing organism Phyllostica cirsii has revealed a biosynthetic gene cluster responsible for the biosynthesis of the phyllostictines, and targeted knockout experiments have proven the link and produced an intermediate.

Talarofuranone, a New Talaroconvolutin Analog from the Endophytic Fungus Talaromyces purpurogenus from Pouteria campechiana Seeds

An endophytic fungus Talaronyces pinpurogenus was isolated from the seeds of the popular edible fruit Pouteria campechiana. The fungus was fermented in potato dextrose agar and the fungal media were extracted with EtOAc. Chromatographic separation of the EtOAc extracts over silica gel, Sephadex LH-20 and preparative thin layer chromatography furnished a furanone analogue of talaroconvolutin A, named talarofuranone (1), along with talaroconvolutin A (2), 4-hydroxyactophenone, tyrosol and ergosterol. The structure of 1 was determined by comparing the NMR data with that of 2 and by HRFABMS.