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International audience; The photophysical properties of Eu3+ and Tb3+ complexes of DOTAGA and DO3A-monoamide conjugates of the Pittsburgh compound B (PiB) chromophore, prepared using linkers of different lengths and flexibilities, and which form stable negatively charged (LnL1), and uncharged (LnL2) complexes, respectively, were studied as potential probes for optical detection of amyloid aggregates. The phenylbenzothiazole (PiB) moiety absorbs light at wavelengths longer than 330 nm with a high molar absorption coefficient in both probes, and acts as an antenna in these systems. The presence of the luminescent Ln3+ ion quenches the excited states of PiB through an energy transfer process from the triplet state of PiB to the metal centre, and structured emission is seen from Eu3+ and Tb3+. The luminescence study indicates the presence of a 5D4 → T1 back transfer process in the Tb3+ complexes. It also provides insights on structural properties of the Eu3+ complexes, such as the high symmetry environment of the Eu3+ ion in a single macrocyclic conformation and the presence of one water molecule in its inner coordination sphere. The overall quantum yield of luminescence of EuL1 is higher than for EuL2. However, their low values reflect the low overall sensitization efficiency of the energy transfer process, which is a consequence of the large distances between the metal center and the antenna, especially in the EuL2 complex. DFT calculations confirmed that the most stable conformation of the Eu3+ complexes involves a combination of a square antiprismatic (SAP) geometry of the chelate and an extended conformation of the linker. The large calculated average distances between the metal center and the antenna point to the predominance of the Förster energy transfer mechanism, especially for EuL2. This study provides insights into the behavior of amyloid-targeted Ln3+ complexes as optical probes, and contributes towards their rational design.

Extracellular pH is an important biomarker in many diseases yet a routine method for imaging tissue pH has not been established in the clinic. Paramagnetic chemical exchange saturation transfer (paraCEST) agents are well-suited for imaging tissue pH because the basis of CEST, chemical exchange, is inherently sensitive to pH. Several previous pH-sensitive paraCEST agents were based upon with an exchanging Ln 3+ bound water molecule as the CEST antenna but this design often added additional line-broadening of the bulk water signal due to T 2 exchange. We report here a pH-sensitive paraCEST agent that lacks an inner-sphere water molecule but contains one Ln-bound -OH group for CEST activation. The Yb 3+ - complex, Yb( 1 ), displayed a single, highly-shifted CEST peak originating from the exchangeable Yb-OH proton, the frequency of which changed over the biologically relevant pH range. CEST images of phantoms ranging in pH from 6-8 demonstrate the potential of this agent for imaging pH. Initial rodent imaging studies showed that Gd( 1 ) remains in the vascular system much longer than anticipated but is cleared slowing via renal filtration.

RATIONALE AND OBJECTIVES Liver inflammation is associated with nonalcoholic steatohepatitis and other pathologies, but noninvasive methods to assess liver inflammation are limited. Inflammation causes endothelial disruption and leakage of plasma proteins into the interstitial space and can result in extravascular coagulation with fibrin deposition. Here we assess the feasibility of using the established fibrin-specific magnetic resonance probe EP-2104R for the noninvasive imaging of fibrin as a marker of liver inflammation. METHODS Weekly 100 mg/kg diethylnitrosamine (DEN) dosing was used to generate liver fibrosis in male rats; control animals received vehicle. Magnetic resonance imaging at 1.5 T with EP-2104R, a matched non-fibrin-binding control linear peptide, or the collagen-specific probe EP-3533 was performed at 1 day or 7 days after the last DEN administration. Imaging data were compared with quantitative histological measures of fibrosis and inflammation. RESULTS After 4 or 5 DEN administrations, the liver becomes moderately fibrotic, and fibrosis is the same if the animal is killed 1 day (Ishak score, 3.62 ± 0.31) or 7 days (Ishak score, 3.82 ± 0.25) after the last DEN dose, but inflammation is significantly higher at 1 day compared with 7 days after the last DEN dose (histological activity index from 0-4, 3.54 ± 0.14 vs 1.61 ± 0.16, respectively; P < 0.0001). Peak EP-2104R signal enhancement was significantly higher in animals imaged at 1 day post-DEN compared with 7 days post-DEN or control rats (29.0% ± 3.2% vs 22.4% ± 2.0% vs 17.0% ± 0.2%, respectively; P = 0.017). Signal enhancement with EP-2104R was significantly higher than control linear peptide at 1 day post-DEN but not at 7 days post-DEN indicating specific fibrin binding during the inflammatory phase. Collagen molecular magnetic resonance with EP-3533 showed equivalent T1 change when imaging rats 1 day or 7 days post-DEN, consistent with equivalent fibrosis. CONCLUSIONS EP-2104R can specifically detect fibrin associated with inflammation in a rat model of liver inflammation and fibrosis.

A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC reaction, additional robust catalytic systems complementary to the copper catalyzed AAC remain in high demand. Herein, Au nanoparticles supported on Al2O3, Fe2O3, TiO2 and ZnO, along with gold reference catalysts (gold on carbon and gold on titania supplied by the World Gold Council) were used as catalysts for the AAC reaction. The supported Au nanoparticles with metal loadings of 0.7–1.6% (w/w relative to support) were able to selectively obtain 1,4-disubstituted-1,2,3-triazoles in moderate yields up to 79% after 15 min, under microwave irradiation at 150 °C using a 0.5–1.0 mol% catalyst loading through a one-pot three-component (terminal alkyne, organohalide and sodium azide) procedure according to the “click” rules. Among the supported Au catalysts, Au/TiO2 gave the best results.

Background Excessive lactate production, a hallmark of cancer, is largely formed by the reduction of pyruvate via lactate dehydrogenase (LDH) to l-lactate. Although d-lactate can also be produced from glucose via the methylglyoxal pathway in small amounts, less is known about the amount of d-lactate produced in cancer cells. Since the stereoisomers of lactate cannot be distinguished by conventional 1H NMR spectroscopy, a chiral NMR shift reagent was used to fully resolve the 1H NMR resonances of d- and l-lactate. Methods The production of l-lactate from glucose and d-lactate from methylglyoxal was first demonstrated in freshly isolated red blood cells using the chiral NMR shift reagent, YbDO3A-trisamide. Then, two different cell lines with high GLO1 expression (H1648 and H 1395) were selected from a panel of over 80 well-characterized human NSCLC cell lines, grown to confluence in standard tissue culture media, washed with phosphate-buffered saline, and exposed to glucose in a buffer for 4 h. After 4 h, a small volume of extracellular fluid was collected and mixed with YbDO3A-trisamide for analysis by 1H NMR spectroscopy. Results A suspension of freshly isolated red blood cells exposed to 5mM glucose produced l-lactate as expected but very little d-lactate. To evaluate the utility of the chiral NMR shift reagent, methylglyoxal was then added to red cells along with glucose to stimulate the production of d-lactate via the glyoxalate pathway. In this case, both d-lactate and l-lactate were produced and their NMR chemical shifts assigned. NSCLC cell lines with different expression levels of GLO1 produced both l- and d-lactate after incubation with glucose and glutamine alone. A GLO1-deleted parental cell line (3553T3) showed no production of d-lactate from glucose while re-expression of GLO1 resulted in higher production of d-lactate. Conclusions The shift-reagent-aided NMR technique demonstrates that d-lactate is produced from glucose in NSCLC cells via the methylglyoxal pathway. The biological role of d-lactate is uncertain but a convenient method for monitoring d-lactate production could provide new insights into the biological roles of d- versus l-lactate in cancer metabolism.

Elucidating the nature, strength, and siting of acid sites in zeolites is fundamental to fathom their reactivity and catalytic behavior. Despite decades of research, this endeavor remains a major challenge. Trimethylphosphine oxide (TMPO) has been proposed as a reliable probe molecule to study the acid properties of solid acid catalysts, allowing the identification of distinct Brønsted and Lewis acid sites and the assessment of Brønsted acid strengths. Recently, doubts have been raised regarding the assignment of the 31P NMR resonances of TMPO-loaded zeolites. Here, it is shown that a judicious control of TMPO loading combined with two-dimensional 1H-31P HETCOR solid-state NMR, DFT, and ab initio molecular dynamics (AIMD)-based computational modeling provides an unprecedented atomistic description of the host-guest and guest-guest interactions of TMPO molecules confined within HZSM-5 molecular-sized voids. 31P NMR resonances usually assigned to TMPO molecules interacting with Brønsted sites of different acid strength arise instead from both changes in the probe molecule confinement effects at ZSM-5 channel system and the formation of protonated TMPO dimers. Moreover, DFT/AIMD shows that the 1H and 31P NMR chemical shifts strongly depend on the siting of the framework aluminum atoms. This work overhauls the current interpretation of NMR spectra, raising important concerns about the widely accepted use of probe molecules for studying acid sites in zeolites. published

The thermodynamic, kinetic, and structural properties of Ln3+ complexes with the bifunctional DO3A-ACE4− ligand and its amide derivative DO3A-BACE4− (modelling the case where DO3A-ACE4− ligand binds to vector molecules) have been studied in order to confirm the usefulness of the corresponding Gd3+ complexes as relaxation labels of targeted MRI contrast agents. The stability constants of the Mg2+ and Ca2+ complexes of DO3A-ACE4− and DO3A-BACE4− complexes are lower than for DOTA4− and DO3A3−, while the Zn2+ and Cu2+ complexes have similar and higher stability than for DOTA4− and DO3A3− complexes. The stability constants of the Ln(DO3A-BACE)− complexes increase from Ce3+ to Gd3+ but remain practically constant for the late Ln3+ ions (represented by Yb3+). The stability constants of the Ln(DO3A-ACE)4− and Ln(DO3A-BACE)4− complexes are several orders of magnitude lower than those of the corresponding DOTA4− and DO3A3− complexes. The formation rate of Eu(DO3A-ACE)− is one order of magnitude slower than for Eu(DOTA)−, due to the presence of the protonated amine group, which destabilizes the protonated intermediate complex. This protonated group causes the Ln(DO3A-ACE)− complexes to dissociate several orders of magnitude faster than Ln(DOTA)− and its absence in the Ln(DO3A-BACE)− complexes results in inertness similar to Ln(DOTA)− (as judged by the rate constants of acid assisted dissociation). The 1H NMR spectra of the diamagnetic Y(DO3A-ACE)− and Y(DO3A-BACE)− reflect the slow dynamics at low temperatures of the intramolecular isomerization process between the SA pair of enantiomers, R-Λ(λλλλ) and S-Δ(δδδδ). The conformation of the Cα-substituted pendant arm is different in the two complexes, where the bulky substituent is further away from the macrocyclic ring in Y(DO3A-BACE)− than the amino group in Y(DO3A-ACE)− to minimize steric hindrance. The temperature dependence of the spectra reflects slower ring motions than pendant arms rearrangements in both complexes. Although losing some thermodynamic stability relative to Gd(DOTA)−, Gd(DO3A-BACE)− is still quite inert, indicating the usefulness of the bifunctional DO3A-ACE4− in the design of GBCAs and Ln3+-based tags for protein structural NMR analysis., This research was funded by the Hungarian National Research, Development and Innovation Office (Projects NKFIH K-128201, K-134694, and FK-134551).

International audience; Given their potential in a better characterization and diagnosis of major pathologies like cancer or chronic inflammation, redox-activated Magnetic Resonance Imaging (MRI) probes have recently attracted much interest from chemists. Such redox responsive probes are capable of reporting on specific biomarkers that are related to tissue redox potential disruption or hypoxia. Lately, this research area has experienced remarkable development, including redox-responsive metal complexes and nanoparticles. Here we critically review the progress with a specific focus on metal-based probes and some nanoparticle examples. We demonstrate, via representative cases, the different molecular mechanisms that can generate a redox-modulated MRI response. They can be based on the redox activity of either the ligand or the metal center, provided the different oxidation states of the metal ion are endowed with different magnetic properties. A particular emphasis is given to recent advances and to the imaging probes that have attained in vivo validation. In overall, we aim to provide the reader with a comprehensive view of how intracellular or extracellular redox buffer systems can be assessed by using MRI contrast agents based on lanthanide or transition metal ions using T1-weighted, T2-weighted, paraCEST 1H or 19F MRI.

Magnetic resonance imaging (MRI) is a powerful non-invasive diagnostic tool that enables distinguishing healthy from pathological tissues, with high anatomical detail. Nevertheless, MRI is quite limited in the investigation of molecular/cellular biochemical events, which can be reached by fluorescence-based techniques. Thus, we developed bimodal nanosystems consisting in hydrophilic quantum dots (QDs) directly conjugated to Gd(III)-DO3A monoamide chelates, a Gd(III)-DOTA derivative, allowing for the combination of the advantages of both MRI and fluorescence-based tools. These nanoparticulate systems can also improve MRI contrast, by increasing the local concentration of paramagnetic chelates. Transmetallation assays, optical characterization, and relaxometric analyses, showed that the developed bimodal nanoprobes have great chemical stability, bright fluorescence, and high relaxivities. Moreover, fluorescence correlation spectroscopy (FCS) analysis allowed us to distinguish nanosystems containing different amounts of chelates/QD. Also, inductively coupled plasma optical emission spectrometry (ICP – OES) indicated a conjugation yield higher than 75%. Our nanosystems showed effective longitudinal relaxivities per QD and per paramagnetic ion, at least 5 times [per Gd(III)] and 100 times (per QD) higher than the r1 for Gd(III)-DOTA chelates, suitable for T1-weighted imaging. Additionally, the bimodal nanoparticles presented negligible cytotoxicity, and efficiently labeled HeLa cells as shown by fluorescence. Thus, the developed nanosystems show potential as strategic probes for fluorescence analyses and MRI, being useful for investigating a variety of biological processes.

International audience; For the development of redox responsive MRI probes based on the MnIII/MnII couple, stable complexation of both reduced and oxidized forms of the metal ion and appropriate tuning of the redox potential in the biologically relevant range are key elements. The water soluble fluorinated Mn-porphyrin derivative Mn-3 satisfies both requirements. In aqueous solutions, it can reversibly switch between MnIII/MnII oxidation states. In the presence of ascorbic acid or beta-mercaptoethanol, the MnIII form undergoes reduction, which is slowly but fully reversed in the presence of air oxygen. A UV-Vis kinetic study of MnIII/MnII reduction under oxygen-free conditions yielded second-order rate constants, k2, of 46.1 M-1 s-1 and 13.8 M-1 s-1 for the reaction with ascorbic acid and beta-mercaptoethanol, respectively. This could correspond, in the absence of oxygen, to a half-life of a few minutes in blood plasma and a few seconds in circulating immune cells where ascorbic acid reaches 20-40 muM and a few mM concentrations, respectively. In contrast to expectations based on the redox potential, reduction with glutathione or cysteine does not occur. It is prevented by the coordination of the glutathione carboxylate group(s) to MnIII in the axial position, as was evidenced by NMR data. Therefore, MnIII-3 acts as an ascorbate specific turn-on MRI probe, which in turn can be re-oxidized by oxygen. The relaxivity increase from the oxidized to the reduced form is considerably improved at medium frequencies (up to 80 MHz) with respect to the previously studied Mn-TPPS4 analogues; at 20 MHz, it amounts to 150%. No in vitro cytotoxicity is detectable for Mn-3 in the typical MRI concentration range. Finally, 19F NMR resonances of MnIII-3 are relatively sharp which could open further opportunities to exploit such complexes as paramagnetic 19F NMR probes.

Two-dimensional 1H–31P heteronuclear correlation NMR of trimethylphosphine oxide (TMPO) adsorbed in zeolites, in tandem with DFT calculations, challenges previous one-dimensional 31P NMR assignments, enabling the unambiguous discrimination of Bronsted and Lewis acid sites, extending the understanding of TMPO:Bronsted complexes formed with distinct stoichiometries at the HZSM-5 zeolite surface, and the proton-transfer mechanism.

International audience; Metal chelates targeted to amyloid peptides are widely explored as diagnostic tools or therapeutic agents. The attachment of a metal complex to amyloid recognition units typically leads to a decrease in peptide affinity. We show here that by separating a macrocyclic GdL chelate and a PiB targeting unit with a long hydrophobic C10 linker, it is possible to attain nanomolar affinities for both Aβ 1‐40 ( K d = 4.4 nM) and amylin ( K d = 4.5 nM), implicated respectively in Alzheimer’s disease and diabetes. The Scatchard analysis of surface plasmon resonance data obtained for a series of amphiphilic, PiB derivative GdL complexes indicate that their Aβ 1‐40 or amylin binding affinity varies with their concentration, thus micellar aggregation state. The GdL chelates also affect peptide aggregation kinetics, as probed by thioflavin‐T fluorescence assays. A 2D NMR study allowed identifying that the hydrophilic region of Aβ 1‐40 is involved in the interaction between the monomer peptide and the Gd 3+ complex. Finally, ex vivo biodistribution experiments were conducted in healthy mice by using 111 In labelled analogues. Their pancreatic uptake, ~3%ID/g, is promising to envisage amylin imaging in diabetic animals.

The NMR relaxivities of the decatungstolanthanoate core-shell nanoparticles, prepared by encapsulating [Ln(W5O18)2]9− polyoxometalates (LnPOM) within amorphous silica shells (K9[Ln(W5O18)2]@SiO2), were studied along the Ln series. The relaxivity of GdPOM is slightly higher than for Gd-DTPA due to second-sphere relaxation effects, but the values for the other paramagnetic LnPOMs are much smaller due to the short T1e values of their Ln3+-ions. The NPs have core-shell spherical structures, with LnPOM-containing cores with 9.5–28 nm diameters, and 4.0–11.0 nm thick amorphous silica shells. In water suspensions, the NPs have negative zeta potentials (−32.5 to −40.0 mV) and time-dependent hydrodynamic diameters (31–195 nm) reflecting the formation of aggregates. The relaxivities of GdPOM@SiO2 NPs suspensions (r1=10.97 (mM Gd)−1 s−1, r2=12.02 (mM Gd)−1 s−1, 0.47 T, 25 °C) are considerably larger than for the GdPOM solutions, indicating that their silica shell is significantly porous to water. This increase is limited by the agglomeration of the complexes in the NPs core, limiting their access to water to those at the core surface. Replacing half of the Gd3+ ions by Eu3+ decreases the NPs r1 and r2 relaxivities at 0.47 T to 20 % and 35 % of their initial values, which are still considerable, but does not affect the efficient luminescence properties of the Eu3+ centers. This indicates that the mixed NPs have potential as dual modality MRI/optical imaging contrast agents.

We report a synthetic strategy to combine different moieties in a single structure using cyanuric chloride (2,4,6-trichlorotriazine) as a starting platform for preparing potential bioimaging agents. This reacted with macrocycles of the porphyrin family and DOTA type metal chelators through mono-, di- and tri- substitution of its chlorine atoms by appropriate nucleophiles, controlling the stepwise by temperature, to produce a system that opens the potential for biomedicinal applications. Porphyrins were chosen as one of the sensing arms, based on their rich structural chemistry, and excellent photophysical properties, while DO3A was used since it can form a versatile aminopropionate functionalized metal ion chelator. All new compounds were fully characterized, both spectroscopically and photophysically. Keywords: Porphyrins, Aza-chelates, Sulfonation, Fluorescence, Biomedicinal applications, Cyanuric chloride

Although nowadays there is a renewed and growing interest in Mn-based contrast agents, there are only few studies dealing with Mn-based lipophilic nanoparticles and how they may be optimized as MRI contrast agents. Three amphiphilic paramagnetic Mn(II) complexes based on derivatives of EDTA and 1,4-DO2A were used for the preparation of lipidic nanoparticles. The length and position of the aliphatic chains were found to control whether either vesicular liposomes, nonvesicular bicelles, or a mixture of both was produced as well as the size and morphology of phospholipid-based self-assembling nanoaggregates. These differences determine whether hydrophilic Gd-based contrast agents or fluorescent dyes can be entrapped in the aqueous core of the nanoaggregate. Structural characterization was performed by cryo-TEM. Detailed

Background Site-specific multimodal nanoplatforms with fluorescent-magnetic properties have great potential for biological sciences. For this reason, we developed a multimodal nanoprobe (BNPs-Tf), by covalently conjugating an optical-magnetically active bimodal nanosystem, based on quantum dots and iron oxide nanoparticles, with the human holo-transferrin (Tf). Methods The Tf bioconjugation efficiency was evaluated by the fluorescence microplate assay (FMA) and the amount of Tf immobilized on BNPs was quantified by fluorescence spectroscopy. Moreover, relaxometric and fluorescent properties of the BNPs-Tf were evaluated, as well as its ability to label specifically HeLa cells. Cytotoxicity was also performed by Alamar Blue assay. Results The FMA confirmed an efficient bioconjugation and the fluorescence spectroscopy analysis indicated that 98% of Tf was immobilized on BNPs. BNPs-Tf also presented a bright fluorescence and a transversal/longitudinal relaxivities ratio (r2/r1) of 65. Importantly, the developed BNPs-Tf were able to label, efficiently and specifically, the Tf receptors in HeLa cells, as shown by fluorescence and magnetic resonance imaging assays. Moreover, this multimodal system did not cause noteworthy cytotoxicity. Conclusions The prepared BNPs-Tf hold great promise as an effective and specific multimodal, highly fluorescent-magnetic, nanoplatform for fluorescence analyses and T2-weighted images. General significance This study developed an attractive and versatile multimodal nanoplatform that has potential to be applied in a variety of in vitro and in vivo studies, addressing biological processes, diagnostic, and therapeutics. Moreover, this work opens new possibilities for designing other efficient multimodal nanosystems, considering other biomolecules in their composition able to provide them important functional properties.

Partial symmetry, i.e., the presence of more than one molecule in the asymmetric unit of a crystal, is a relatively rare phenomenon in small-molecule crystallography, but is quite common in protein crystallography, where it is typically known as non-crystallographic symmetry (NCS). Several papers in literature propose molecular determinants such as crystal contacts, thermal factors, or TLS parameters as an explanation for the phenomenon of intrinsic asymmetry among molecules that are in principle equivalent. Nevertheless, are all of the above determinants the cause or are they rather the effect? In the general frame of the NCS often observed in crystals of biomolecules, this paper deals with nickel(II)-substituted human carbonic anhydrase(II) (hCAII) and its SAD structure determination at the nickel edge. The structure revealed two non-equivalent molecules in the asymmetric unit, the presence of a secondary nickel-binding site at the N-terminus of both molecules (which had never been found before in the nickel-substituted enzyme) and two different coordination geometries of the active site nickel (hexa-coordinated in one molecule and mainly penta-coordinated in the other). The above-mentioned standard molecular crystallographic determinants of this asymmetry are analyzed and presented in detail for this particular case. From these considerations, we speculate on the existence of a fundamental, although yet unknown, common cause for the partial symmetry that is so often encountered in X-ray structures of biomolecules.

Ethnopharmacological relevance Leaves extracts from Cymbopogon citratus (DC) Stapf. are widely used in traditional medicine exhibiting several in vivo biological activities, including antidiabetic. Several flavonoids, including aglycones and glycosides, were reported in this plant and previous studies suggested that flavonoids may interact with targets related to diabetes. Aim of the study Evaluated the hypoglycemic activity of C. citratus flavonoids through α-glucosidase inhibition and assess the structure-activity relationship using molecular docking studies. Material and methods An infusion of C. citratus leaves and its flavonoid-rich fraction were prepared. Five flavonoids from this fraction were isolated and structurally characterized by UV spectral analysis with shift reagents, HPLC-PDA-ESI/MSn and 1H NMR. The antidiabetic potential of C. citratus infusion, its flavonoid-rich fraction, glycosylated flavonoids and aglycones was evaluated trough the in vitro inhibition of yeast α-glucosidase. Posteriorly, molecular docking of the tested flavonoids was performed to investigate its possible interactions with the α-glucosidase pocket. Results The infusion of C. citratus, its flavonoid-rich fraction, luteolin and five flavone glycosides namely, luteolin 6-C-β-glucopyranoside (isoorientin), luteolin 7-O-neohesperidoside (ionicerin), luteolin 7-O-β-glucopyranoside (cynaroside), Luteolin 2″-O-rhamnosyl-C-(6-deoxy-ribo-hexos-3-ulosyl) (cassiaoccidentalin B), luteolin 6-C-α-arabinofuranosil-(1→2)-α-L-rhamnopyranoside (kurilesin A) showed higher inhibitory activity than the reference drug. This activity increased by the addition of a sugar moiety. However, the di-glycosides were less active than mono-glycosides. The docking studies showed interactions of sugar moieties and A or B rings with the catalytic pocket mainly through hydrogen bonds. Conclusions Our results corroborate the potential of C. citratus as a medicinal plant for the treatment of diabetes and revealed that its flavonoid glycosides has hypoglycemic effect and can be explored as drug candidates to act as α-glucosidase inhibitors in the treatment of diabetes.

Mn(III) porphyrins have great potential as Gd-free MRI contrast agents because both the cation and the ligand have interesting properties. The redox properties of the Mn(III)-ion can be exploited for the preparation of reactive oxygen species for therapy. Moreover, the porphyrin ligand allows these complexes to have a high affinity for tumor tissues. The inherent properties of the porphyrin ligands make these systems attractive for photothermal, photodynamic, and sonodynamic therapies. Therefore, these systems are attractive for the development of theranostics for MRI-guided therapy. For the magnetic field strengths at which most clinical MRI machines operate at present (0.5–1.5 T), the longitudinal relativity of low-molecular-weight complexes is even higher than that of the classical Gd-based contrast agents. This review gives an overview of the developments in the field of Mn(III) porphyrin contrast agents during the last 30 years.

The number of scientific reports on the field of imaging in biomedical sciences is rising massively, with the emergence of “noninvasive” in vivo imaging technologies, of which Magnetic Resonance Imaging (MRI) is considered to be among the top techniques in modern Medical Imaging. These techniques manage to detect events at molecular and cellular levels, providing a faster diagnostic evaluation to oncology patients and consequently hastening drug development processes. Of the many contrast agents developed by Organic Chemists during the last decades, tetrapyrrolic macrocycles like porphyrins and related compounds, like phthalocyanines, represent some of the oldest, most widely studied chemical structures in biomedical applications. These macrocyclic structures display intrinsic affinity for tumor localization, and their well-described photosensitizing and photophysical features allured many scientists toward their potential use as contrast agents in a variety of in vivo imaging technologies, namely in the MRI technique. Furthermore, a special emphasis is put on the development of multimodal contrast agents, which may be the future of Medical Imaging. This review intends to give an insight on developments on MRI technologies involving tetrapyrrolic-based contrast agents for cancer detection. It is a Chemist’s view, regarding the synthesis of the crucial contrast agents, selecting influential milestones over the last few decades on this field, along with pertinent reflections pointing to future guidelines.

International audience; Aggregation of misfolded proteins and progressive polymerization of otherwise soluble proteins is a common hallmark of a wide range of highly debilitating and increasingly prevalent diseases, including amyotrophic lateral sclerosis, cerebral amyloid angiopathy, type II diabetes and Parkinson's, Huntington's and Alzheimer's diseases. There is a growing interest in creating imaging agents to detect such aggregates in various imaging modalities, including PET, SPECT and MRI. We present here an overview of recent efforts from the perspective of early diagnosis of amyloid diseases, with a major focus on Aβ detection and metal complexes bearing PiB units.

[Abstract] In the periodical system, the lanthanides (the 15 elements in the periodic table between barium and hafnium) are unique in the sense that their trivalent cations have their valence electrons hidden behind the 5s and 5p electrons. They show a gradual decrease in ionic radius with increasing atomic number (also known as the lanthanide contraction). The resulting steric effects determine to a large extent the geometries of complexes of these ions. Here, we discuss these effects, particularly upon the properties of the complexes in aqueous solution, for selected families of Ln3+-complexes of oxycarboxylate and aminocarboxylate ligands. The physical properties of the cations are very different, which is very useful for the elucidation of the configuration, conformation and the dynamics of the complexes by X-ray techniques, NMR spectroscopy, and optical techniques. Often the structural analysis is assisted by computational methods.

Purpose: To study the association between the assessment of central macular vascular layers by optical coherence tomography angiography (OCT-A) and peripheral nonperfusion evaluated by fluorescein angiography (FA) in patients with retinal venous occlusion (RVO). Methods: Retrospective review of RVO patients without macular edema. Patients underwent a comprehensive ophthalmic examination including FA, spectral-domain OCT, and OCT-A. Significant ischemia was defined as nonperfusion areas superior or equal to the equivalent of one retinal quadrant on FA. Vascular density (VD) and foveal avascular zone were measured using AngioAnalytics software. Fractal dimension (FD) and lacunarity (LAC) were computed using an algorithm designed by MATLAB (MathWorks, Natick, MA). These variables were used to build a model that translates their association with OCT-A parameters. Results: There were 48 eyes (48 patients) of which 19 had significant peripheral nonperfusion. Deep capillary plexus FD, VD, and LAC were associated with significant ischemia. In fact, regarding the association with this outcome, LAC alone had the highest area under the curve (AUC = 0.88) followed by FD (AUC = 0.85) and VD (AUC = 0.73). The multivariable model that included LAC and VD, adjusted by best-corrected visual acuity (BCVA) achieved the best performance for the identification of severe nonperfusion on wide-field FA (AUC = 0.93). Conclusions: The characteristics of the central macular deep capillary plexus on OCT-A may be associated with peripheral nonperfusion on FA, particularly the combination of LAC and vessel density after adjusting by BCVA. Translational Relevance: Fractal-based metrics applied to OCT-A may become a valuable marker of ischemia in RVO and help guide the clinical decision to perform invasive angiography. publishersversion published

Solid state NMR (SSNMR) has earned a substantial success in the characterization of paramagnetic systems over the last decades. Nowadays, the resolution and sensitivity of solid state NMR in biological molecules has improved significantly and these advancements can be translated into the study of paramagnetic biomolecules. However, the electronic properties of different metal centers affect the quality of their SSNMR spectra differently, and not all systems turn out to be equally easy to approach by this technique. In this review we will try to give an overview of the properties of different paramagnetic centers and how they can be used to increase the chances of experimental success.

International audience; Superparamagnetic maghemite core–porous silica shell nanoparticles, γ-Fe2O3@SiO2 (FS), with 50 nm diameter and a 10 nm core, impregnated with paramagnetic complexes b-Ln ([Ln(btfa)3(H2O)2]) (where btfa = 4,4,4-trifluoro-l-phenyl-1,3-butanedione and Ln = Gd, Eu, and Gd/Eu), performing as promising trimodal T1–T2 MRI and optical imaging contrast agents, are reported. These nanosystems exhibit a high dispersion stability in water and no observable cytotoxic effects, witnessed by intracellular ATP levels. The structure and superparamagnetic properties of the maghemite core nanocrystals are preserved upon imbedding the b-Ln complexes in the shell. Hela cells efficiently and swiftly internalize the NPs into the cytosol, with no observable cytotoxicity below a concentration of 62.5 μg mL–1. These nanosystems perform better than the free b-Gd complex as T1 (positive) contrast agents in cellular pellets, while their performance as T2 (negative) contrast agents is similar to the FS. Embedding of the b-Eu complex in the silica pores endows the nanoparticles with strong luminescence properties. The impregnation of gadolinium and europium complexes in a 1:1 ratio afforded a trimodal nanoplatform performing as a luminescent probe and a double T1 and T2 MRI contrast agent even more efficient than b-Gd used on its own, as observed in cell-labeled imaging experiments and MRI cell pellets.

A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX(κP-DAPTA)3] (1: X = Br, 2: X = I) and [Cu(μ-X)(κP-DAPTA)2]2 (3: X = Br, 4: X = I) were immobilized on activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on these materials after surface functionalization. The immobilized copper(I) complexes have shown favorable catalytic activity for the one-pot, microwave-assisted synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition reaction (CuAAC). The heterogenized systems with a copper loading of only 1.5–1.6% (w/w relative to carbon), established quantitative conversions after 15 min, at 80 °C, using 0.5 mol% of catalyst loading (relative to benzyl bromide). The most efficient supports concerning heterogenization were CNT treated with nitric acid and NaOH, and involving complexes 2 and 4 (in the same order, 2_CNT-ox-Na and 4_CNT-ox-Na). The immobilized catalysts can be recovered and recycled by simple workup and reused up to four consecutive cycles although with loss of activity.

A series of Mn(II) aminophosphonate complexes were successfully synthesized and intercalated into the hydroxy double salt [Zn5(OH)8]Cl2·yH2O. Complex incorporation led to an increase in the interlayer spacing from 7.8 to 10–12 A. Infrared spectroscopy showed the presence of the characteristic vibration peaks of the Mn(II) complexes in the intercalates' spectra, indicating successful incorporation. The complex-loaded composites had somewhat lower proton relaxivities than the pure complexes. Nevertheless, these intercalates may have use as MRI contrast agents for patients with poor kidney function, where traditional Gd(III)-based contrast agents cause severe renal failure.

Background Overexpression of transferrin receptors (TfRs), which are responsible for the intracellular uptake of ferric transferrin (Tf), has been described in various cancers. Although molecular biology methods allow the identification of different types of receptors in cancer cells, they do not provide features about TfRs internalization, quantification and distribution on cell surface. This information can, however, be accessed by fluorescence techniques. In this work, the quantum dots (QDs)' unique properties were explored to strengthen our understanding of TfRs in cancer cells. Methods QDs were conjugated to Tf by covalent coupling and QDs-(Tf) bioconjugates were applied to quantify and evaluate the distribution of TfRs in two human glioblastoma cells lines, U87 and DBTRG-05MG, and also in HeLa cells by using flow cytometry and confocal microscopy. Results HeLa and DBTRG-05MG cells showed practically the same TfR labeling profile by QDs-(Tf), while U87 cells were less labeled by bioconjugates. Furthermore, inhibition studies demonstrated that QDs-(Tf) were able to label cells with high specificity. Conclusions HeLa and DBTRG-05MG cells presented a similar and a higher amount of TfR than U87 cells. Moreover, DBTRG-05MG cells are more efficient in recycling the TfR than the other two cells types. General significance This is the first study about TfRs in human glioblastoma cells using QDs. This new fluorescent tool can contribute to our understanding of the cancer cell biology and can help in the development of new therapies targeting these receptors.

Mesoporous silica nanoparticles with a superparamagnetic iron oxide core were prepared in this work, in order to obtain multifunctional platforms with adequate features for cancer theranostics. Three different core-shell nanocomplexes were obtained: IO-OAm/mSiO2, IO-APTES/mSiO2 and IO/SiO2/mSiO2. In the case of IO-OAm/mSiO2 and IO-APTES/mSiO2, iron oxide (IO) was obtained by thermal decomposition, having in this case a coating of oleylamine (OAm) that was in the second formulation exchanged by (3-aminopropyl)triethoxysilane ligand (APTES). Regarding the IO/SiO2/mSiO2 formulation, iron oxide was synthesized by microemulsion. The mesoporous silica shell (mSiO2) on the IO nanoparticles was obtained by sol-gel and the final materials were dried by supercritical fluids drying. VSM confirmed the superparamagnetic behaviour of the nanoparticles, leading to MS of 4.0, 1.8 and 10.2 emu·g−1, for IO-OAm/mSiO2, IO-APTES/mSiO2 and IO/SiO2/mSiO2, respectively. NMR relaxometry has shown the potential of these nanoparticles to be used as T2 contrast agents, with r2 values as high as 63.93 s−1·mM−1 Fe. The three types of nanoparticles exhibited loading contents of epirubicin of ~3% and drug release percentages of 19% for IO-OAm/mSiO2, 24% for IO-APTES/mSiO2 and 31% for IO/SiO2/mSiO2. The cytotoxicity of drug-loaded and non-loaded most promising nanoparticles was assessed, showing high potential of these platforms for application as anticancer drug carriers.

(1) Background: Cholesterol bioaccessibility is an indicator of cholesterol that is available for absorption and therefore can be a measure of hypocholesterolemic potential. In this work, the effect of commercial espresso coffee and coffee extracts on cholesterol solubility are studied in an in vitro model composed by glycodeoxycholic bile salt, as a measure of its bioaccessibility. (2) Methods: Polysaccharide extracts from coffees obtained with different extraction conditions were purified by selective precipitation with ethanol, and their sugars content were characterized by GC-FID. Hexane extraction allowed us to obtain the coffee lipids. Espresso coffee samples and extracts were tested regarding their concentration dependence on the solubility of labeled 13C-4 cholesterol by bile salt micelles, using quantitative 13C NMR. (3) Results and Discussion: Espresso coffee and coffee extracts were rich in polysaccharides, mainly arabinogalactans and galactomannans. These polysaccharides decrease cholesterol solubility and, simultaneously, the bile salts’ concentration. Coffee lipid extracts were also found to decrease cholesterol solubility, although not affecting bile salt concentration. (4) Conclusions: Coffee soluble fiber, composed by the arabinogalactans and galactomannans, showed to sequester bile salts from the solution, leading to a decrease in cholesterol bioaccessibility. Coffee lipids also decrease cholesterol bioaccessibility, although the mechanism of action identified is the co-solubilization in the bile salt micelles. The effect of both polysaccharides and lipids showed to be additive, representing the overall effect observed in a typical espresso coffee. The effect of polysaccharides and lipids on cholesterol bioaccessibility should be accounted on the formulation of hypocholesterolemic food ingredients., Nutrients, 12 (2), ISSN:2072-6643

This article belongs to the Special Issue Targeted Drug Delivery., Gold nanoparticles (AuNPs) are interesting for the design of new cancer theranostic tools, mainly due to their biocompatibility, easy molecular vectorization, and good biological half-life. Herein, we report a gold nanoparticle platform as a bimodal imaging probe, capable of coordinating Gd3+ for Magnetic Resonance Imaging (MRI) and 67Ga3+ for Single Photon Emission Computed Tomography (SPECT) imaging. Our AuNPs carry a bombesin analogue with affinity towards the gastrin releasing peptide receptor (GRPr), overexpressed in a variety of human cancer cells, namely PC3 prostate cancer cells. The potential of these multimodal imaging nanoconstructs was thoroughly investigated by the assessment of their magnetic properties, in vitro cellular uptake, biodistribution, and radiosensitisation assays. The relaxometric properties predict a potential T1- and T2- MRI application. The promising in vitro cellular uptake of 67Ga/Gd-based bombesin containing particles was confirmed through biodistribution studies in tumor bearing mice, indicating their integrity and ability to target the GRPr. Radiosensitization studies revealed the therapeutic potential of the nanoparticles. Moreover, the DOTA chelating unit moiety versatility gives a high theranostic potential through the coordination of other therapeutically interesting radiometals. Altogether, our nanoparticles are interesting nanomaterial for theranostic application and as bimodal T1- and T2- MRI / SPECT imaging probes., This research was funded by FCT (Portuguese Foundation for Science and Technology), grant numbers EXCL/QEQ-MED/0233/2012, UID/Multi/04349/2013 and PTDC/MED-QUI/29649/2017. CFGCG and MMCAC thank FCT and FEDER through the COMPETE Program for funding the CQC (UID/QUI/00313/2013 and PEst-OE/QUI/UI0313/2014). P.L-L. thanks Ministry of Economy, Industry and Competitiviy for SAF2017-83043-R, and Comunity of Madrid, FEDER and FSE for S2017/BMD-3688.

Introduction The evaluation of drug's cytotoxicity is a crucial step in the development of new pharmacological compounds. 31P NMR can be a tool for toxicological screening, as it enables the study of drugs' cytotoxicity and their effect on cell energy metabolism in a real-time, in a non- invasive and non-destructive way. This paper details a step-by-step protocol to implement a bioreactor system able to maintain cell viability during NMR acquisitions, at high cell densities and for several hours, enabling toxicological evaluation of pharmacological compounds in living cells. Method HeLa cells were immobilized in agarose gel threads and continuously perfused with oxygenated medium inside a 5 mm NMR tube. Signals corresponding to intracellular high-energy phosphorous compounds were continuously monitored by 31P NMR to assess cell energy levels, intracellular pH and intracellular free Mg2+ concentrations ([Mg2+]f) under control and in the presence of two different cytotoxic drugs, calix-NH2 or 5-fluorouracil (5-FU). Results The bioreactor system was effective in maintaining cell energy levels as well as intracellular pH and [Mg2+]f along time, with a good 31P NMR signal to noise ratio. Calix-NH2 and 5-FU decreased cell energy levels by 35% and 39%, respectively, with a negligible increase in intracellular [Mg2+]f, and without affecting intracellular pH. Discussion The immobilization and perfusion system here detailed, along with 31P NMR, is useful in toxicological evaluation of new pharmacological compounds, enabling the continuous assessment of drugs' effect on energy levels, intracellular pH and [Mg2+]f in intact cells, for several hours without compromising cell viability.

Ethnopharmacological relevance Acanthus mollis is a plant native to the Mediterranean region, traditionally used as diuretic, anti-inflammatory and soothing of the mucous membranes of the digestive and urinary tract and externally as healing of wounds and burns, also demonstrating analgesic and anti-inflammatory activities. However, studies focused on its phytochemical composition as well as scientific proof of Acanthus mollis efficacy are scarce. Aim of the study The proposed work aims to perform a phytochemical characterization and evaluation of the therapeutic potential of Acanthus mollis, based on biological properties that support its traditional uses. Material and methods In this study, an 96% ethanol extract from Acanthus mollis leaves was obtained and its phytochemical composition evaluated using High Performance Liquid Chromatography with Photodiode Array Detector coupled to Electrospray Ionization Mass Spectrometry (HPLC-PDA-ESI/MSn). The chemical structure of the compound isolated was elucidated using 1H and 13C Nuclear Magnetic Resonance (NMR), 1H-correlation spectroscopy (1H–COSY), heteronuclear single quantum correlation (HSQC) and heteronuclear multiple-bond correlation (HMBC). The quantification of the constituents was performed using two external standards (2,4-dihydroxy-1,4-benzoxazin-3-one and verbascoside). The antioxidant activity was determined by the 2,2-diphenyl-1-pycrylhydrazyl (DPPH) assay. Anti-inflammatory activity was determined measuring the inhibition of nitric oxide production by RAW 264.7 macrophages stimulated with the TLR4 agonist lipopolysaccharide (LPS) and through lipoxygenase (LOX) inhibition assay. The cytotoxicity was screened on two lines (RAW 264.7 and HaCaT) using the resazurin assay. Results Compounds such as verbascoside and its derivatives, as well as benzoxazinoids were found as the main constituents. A percentage of 5.58% was verified for the 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) derivatives. DIBOA was the main compound of the extract. Significant concentrations were also found for phenylpropanoids, which constitute about 4.39% of the total compounds identified. This extract showed antioxidant capacity against DPPH (IC50 = 40.00 ± 1.59 μg/mL) and superoxide anion (IC50 = 29.42 ± 1.99 μg/mL). It also evidenced anti-inflammatory potential in RAW 264.7 macrophages, presenting capacity for nitric oxide reduction (IC50 = 28.01 μg/mL). Moreover, in vitro studies have shown that this extract was able to inhibit the lipoxygenase, with an IC50 of 104.39 ± 4.95 µg/mL. Importantly, all effective concentrations were devoid of cytotoxicity in keratinocytes, thus highlighting the safety of the extract for the treatment of skin inflammatory related diseases. Concerning macrophages it was also possible to disclose concentrations showing anti-inflammatory activity and without cytotoxicity (up to 30 µg/mL). The benzoxazinoid DIBOA demonstrated a considerable anti-inflammatory activity suggesting its important contribution to this activity. Conclusions These results corroborate the anti-inflammatory properties traditionally attributed to this plant. Among the compounds identified in this study, benzoxazinoids exhibited a significant anti-inflammatory activity that was never previously described. Ethanol seems to be a good option for the extraction of these bioactive compounds, since relevant antioxidant/anti-radical and anti-inflammatory activities were found for this extract.

Alzheimer's disease (AD) is the most common chronic neurodegenerative disorder leading to progressive and irreversible decline of cognitive functions. Together with neurofibrillary tangles, the formation of brain extracellular plaques containing amyloid-β peptides is a major neuropathological hallmark associated with AD. The development of clinical imaging techniques for early detection of AD is a primary health objective. We present here an overview of recent progress in the chemistry of molecular probes for the in vivo MRI detection of Aβ deposits in the brain to improve early diagnosis of AD.

This work reports the mastered design of novel water-dispersible superparamagnetic iron oxide nanomaterials with enhanced magnetic properties and reduced size. A straightforward cost-effective aqueous coprecipitation route was developed, based on the use of three new coprecipitation agents: the polydentate bases diethanolamine, triethanolamine and triisopropanolamine. Through the selection of these alkanolamines which presented different complexing properties, an improvement of the surface spin order could be achieved upon the reduction of the nanomaterial dimensions (from 8.7 to 3.8 nm) owing to the complexation of the polydentate bases with the subcoordinated iron cations on the particle surface. In particular, the alkanolamine with the highest chelating ability (triethanolamine) led to the nanomaterial with the smallest size and the thinnest magnetic “dead” layer. In order to evaluate the importance of the dual control of size and magnetism, the relaxometric properties of the nanomaterials were investigated, whereby maximum values of transverse relaxivity r2 of 300.30 and 253.92 mM−1 s−1 at 25 and 37 °C, respectively (at 20 MHz) were achieved, making these nanomaterials potential T2-weighted MRI contrast agents. Moreover, these values were significantly higher than those reported for commercial T2 contrast agents and other iron oxides with identical dimensions. Hence, we were able to demonstrate that the r2 enhancement cannot only be achieved by an increase of particle/cluster size, but also through the precise control of the surface magnetic properties while constraining the nanomaterial dimensions. These achievements open up new perspectives on the mastered design of magnetic nanoprobes, overcoming the limitations related to the deleterious effect of size reduction.

A detailed analysis of paramagnetic NMR shifts in a series of isostructural lanthanide complexes relavant to PARASHIFT contrast agents reveals unexpected trends in the magnetic susceptibility anisotropy that cannot be explained by the commonly used Bleaney's theory. Ab initio calculations reveal that the primary as-sumption of Bleaney's theory - that thermal energy is larger than the ligand field splitting - does not hold for the lanthanide complexes in question, and likely for a large fraction of lanthanide complexes in general. This makes the orientation of the magnetic susceptibility tensor differ significantly between complexes of different lanthanides with the same ligand: thus, one of the most popular assumptions about isostructural lanthanide series is incorrect.

Three triaza macrocyclic ligands, H6NOTP (1,4,7-triazacyclononane-N,N′,N″-trimethylene phosphonic acid), H4NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N′,N″-dimethylenecarboxylic acid), and H5NOA2P (1,4,7-triazacyclononane-N,N′-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A 1H, 31P and 71Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of 71Ga NMR spectra gave information on the symmetry of the Ga3+ coordination sphere and the stability of the chelates towards hydrolysis. The 31P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The 1H NMR spectra allowed the analysis of the structure and the number of species in solution. 31P and 1H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log KHi) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log KGaL =34.44 (0.04) and stepwise protonation constants of Ga (NOA2P)2− were determined by potentiometry and 69Ga and 31P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled 67Ga(NO2AP)− and 67Ga (NOA2P)2−chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed., The authors thank the financial support from the Fundação para a Ciência e Tecnologia (F.C.T., Portugal, projects RREQ/481/QUI/2006 and RECI/QEQ-QFI/0168/2012), the Rede Nacional de RMN (RNRMN), the Hungarian Scientific Research Fund (OTKA grants K-109029 and K-120224), the János Bolyai Research Scholarship (Gy.T.) of the Hungarian Academy of Sciences and the EU COST Action TD1004 “Theragnostics Imaging and Therapy”. The research was also supported by the EU and co-financed by the European Regional Development Fund (FEDER) under the projects CENTRO-07-CT62-FEDER) and GINOP-2.3.2-15-2016-00008., info:eu-repo/semantics/publishedVersion

International audience; Monoclinic and cubic europium-doped Gd2O3 structures were selectively synthesized by the glycine–nitrate process by fine control of the synthesis temperature through the crucial fuel/oxidant ratio. The cubic phase is obtained under fuel-rich conditions, whereas stoichiometric conditions induce the simultaneous formation of cubic and monoclinic polymorphs. The samples were subjected to appropriate sintering to obtain highly crystalline and carbon-free materials. The average nanoparticle (NP) size determined by TEM for these nanopowders (23 nm) agrees with the average crystallite sizes obtained from XRD Rietveld analysis; therefore, the particles are monocrystalline. Both electron energy loss spectroscopy (EELS) and photoluminescence studies showed that the europium-doped NPs are highly luminescent, and the Eu3+ ions are homogeneously distributed over the whole material as well as over the two gadolinium crystallographic sites of the cubic phase. These fluorescent NPs exhibit relaxivities that define them as potential T1 contrast agents for further biomedical applications.

et al., Flavonoids from lemongrass – Cymbopogon citratus (DC.) Stapf – leaves infusion, a commonly consumed beverage for the treatment of inflammatory-related conditions, were investigated in this work. Luteolin O-, C- and O,C-glycosides were isolated and identified by nuclear magnetic resonance, being the cassiaoccidentalin B structure fully characterized for the first time in lemongrass. The anti-inflammatory activity of luteolin and its glycosides was evaluated in lipopolysaccharide-stimulated macrophages. Luteolin glycosides demonstrated less cytotoxicity than luteolin itself. Although glycosylation decreases luteolin anti-inflammatory properties, being higher to C-glycosylation, an inhibitory effect on inflammatory mediator production (nitric oxide and IL-1β) was verified for the luteolin 7-O-β-glucopyranoside, without cytotoxic effects. Therefore, luteolin glycosides from lemongrass infusion are evidenced as a less toxic alternative to current anti-inflammatory drugs with promising use in pharmaceutical and food supplement industries. Additionally, this work establishes structure–activity relationships, which constitutes valuable information in the design of anti-inflammatory luteolin glycosides devoid of toxicity., This work was supported by FEDER/COMPETE (FCOMP-01-0124-FEDER-011096) and Foundation for Science and Technology (FCT), by the projects PTDC/SAU-FCF/105429/2008, PEst-OE/SAU/UI0177/2011 and PEst-C/SAU/LA0001/2011, and by PhD fellowshipsSFRH/BD/46281/2008 and SFRH/BD/72918/2010.

The availability of commercial 68Ge/68Ga cyclotron-independent 68Ga3+ generators is making Positron Emission Tomography (PET) accessible to most hospitals, which is generating a surge of interest in the design and synthesis of bi-functional chelators for Ga3+. In this work we introduce the NO2A-N-(α-amino)propionic acid family of chelators based on the triazacyclononane scaffold. Complexation of the parent NO2A-N-(α-amino)propionic acid chelator and of a low molecular weight (model) amide conjugate with Ga3+ was studied by 1H and 71Ga NMR. The Ga3+ chelate of the amide conjugate shows pH-independent N3O3 coordination in the pH range 3–10 involving the carboxylate group of the pendant propionate arm in a 6 member chelate. For the Ga[NO2A-N-(α-amino)propionate] chelate, a reversible pH-triggered switch from Ga3+ coordination to the carboxylate group to coordination to the amine group of the propionate arm was observed upon pH increase/decrease in the pH range 4–6. This phenomenon can conceivably constitute the basis of a physiological pH sensor. Both complexes are stable in the physiological range. The [67Ga][NO2A-N-(α-benzoylamido)propionate] chelate was found to be stable in human serum. Biodistribution studies of the 67Ga3+-labeled pyrene butyric acid conjugate NO2A-N-(α-pyrenebutanamido)propionic acid revealed that, despite its high lipophilicity and concentration-dependent aggregation properties, the chelate follows mainly renal elimination with very low liver/spleen accumulation and no activity deposition in bones after 24 hours. Facile synthesis of amide conjugates of the NO2A-N-(α-amino)propionic acid chelator, serum stability of the Ga3+ chelates and fast renal elimination warrant further evaluation of this novel class of chelators for PET applications.

Catalysis of collagen degradation by matrix metalloproteinase 1 (MMP-1) has been proposed to critically rely on flexibility between the catalytic (CAT) and hemopexin-like (HPX) domains. A rigorous assessment of the most readily accessed conformations in solution is required to explain the onset of substrate recognition and collagenolysis. The present study utilized paramagnetic NMR spectroscopy and small angle x-ray scattering (SAXS) to calculate the maximum occurrence (MO) of MMP-1 conformations. The MMP-1 conformations with large MO values (up to 47%) are restricted into a relatively small conformational region. All conformations with high MO values differ largely from the closed MMP-1 structures obtained by x-ray crystallography. The MO of the latter is ∼20%, which represents the upper limit for the presence of this conformation in the ensemble sampled by the protein in solution. In all the high MO conformations, the CAT and HPX domains are not in tight contact, and the residues of the HPX domain reported to be responsible for the binding to the collagen triple-helix are solvent exposed. Thus, overall analysis of the highest MO conformations indicated that MMP-1 in solution was poised to interact with collagen and then could readily proceed along the steps of collagenolysis. Background: Matrix metalloproteinase-1 (MMP-1) collagenolysis relies on interdomain flexibility. Results: In all high maximum occurrence conformations, the MMP-1 hemopexin-like domain residues reported responsible for binding to the collagen triple-helix are solvent exposed. Conclusion: MMP-1 in solution is poised to interact with collagen and proceed along the steps of collagenolysis. Significance: The maximum occurrence approach can evaluate the predominant domain conformations for numerous multidomain enzymes.

PURPOSE:This study is aimed at demonstrating the in vivo potential of Gd(III)-loaded glucan particles (Gd-GPs) as magnetic resonance imaging (MRI)-positive agents for labeling and tracking phagocytic cells. PROCEDURE:GPs were obtained from Saccharomyces cerevisae and loaded with the water-insoluble complex Gd-DOTAMA(C18)2. The uptake kinetics of Gd-GPs by murine macrophages was studied in vitro and the internalization mechanism was assessed by competition assays. The in vivo performance of Gd-GPs was tested at 7.05T on a mouse model of acute liver inflammation. RESULTS:The minimum number of Gd-GPs-labeled J774.A1 macrophages detected in vitro by MRI was ca. 300 cells/μl of agar, which is the lowest number ever reported for cells labeled with a positive T1 agent. Intravenous injection of macrophages labeled with Gd-GPs in a mouse model of liver inflammation enabled the MRI visualization of the cellular infiltration in the diseased area. CONCLUSIONS:Gd-GPs represent a promising platform for tracking macrophages by MRI as a T1 alternative to the golden standard T2-based iron oxide particles.

New methods for creating theranostic systems with simultaneous encapsulation of therapeutic, diagnostic, and targeting agents are much sought after. This work reports for the first time the use of coaxial electrospinning to prepare such systems in the form of core-shell fibers. Eudragit S100 was used to form the shell of the fibers, while the core comprised poly(ethylene oxide) loaded with the magnetic resonance contrast agent Gd(DTPA) (Gd(III) diethylenetriaminepentaacetate hydrate) and indomethacin as a model therapeutic agent. The fibers had linear cylindrical morphologies with clear core-shell structures, as demonstrated by electron microscopy. X-ray diffraction and differential scanning calorimetry proved that both indomethacin and Gd(DTPA) were present in the fibers in the amorphous physical form. This is thought to be a result of intermolecular interactions between the different components, the presence of which was suggested by infrared spectroscopy. In vitro dissolution tests indicated that the fibers could provide targeted release of the active ingredients through a combined mechanism of erosion and diffusion. The proton relaxivities for Gd(DTPA) released from the fibers into tris buffer increased (r1 = 4.79-9.75 s(-1) mM(-1); r2 = 7.98-14.22 s(-1) mM(-1)) compared with fresh Gd(DTPA) (r1 = 4.13 s(-1) mM(-1) and r2 = 4.40 s(-1) mM(-1)), which proved that electrospinning has not diminished the contrast properties of the complex. The new systems reported herein thus offer a new platform for delivering therapeutic and imaging agents simultaneously to the colon.

International audience; PURPOSE:The aim of this work is to develop an efficient and fully automated radiosynthesis of three derivatives of the Pittsburgh compound B labeled with gallium-68 for the detection of amyloid plaques.PROCEDURES:The radiolabeling of the precursors and purification of the radiolabeled agents by high pressure liquid chromatography has been studied prior to their in vitro and in vivo evaluations.RESULTS:The complete process led, in 50 min, to pure Ga-68 products in a 12-38 % yield and with appreciable specific radioactivity (SRA, 85-168 GBq/μmol) which enabled us to demonstrate a considerable in vivo stability of the products. Unfortunately, this result was associated with a poor blood-brain barrier (BBB) permeability and a limited uptake of our compounds by amyloid deposits was observed by in vitro autoradiography.CONCLUSION:Although we have not yet identified a compound able to significantly mark cerebral amyloidosis, this present investigation will likely contribute to the development of more successful Ga-68 radiotracers.