Some things old, new and borrowed: Delivery of dabrafenib and vemurafenib to melanoma cells via self-assembled nanomicelles based on an amphiphilic dendrimer

Two clinically approved anticancer drugs targeting BRAF in melanoma patients - dabrafenib (DAB) and vemurafenib (VEM) - have been successfully encapsulated into nanomicelles formed upon self-assembly of an amphiphilic dendrimer AD based on two C18 aliphatic chains and a G2 PAMAM head. The process resulted in the formation of well-defined (∼10 nm) core-shell nanomicelles (NMs) with excellent encapsulation efficiency (∼70% for DAB and ∼60% for VEM) and good drug loading capacity (∼27% and ∼24% for DAB and VEM, respectively). Dynamic light scattering (DLS), transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), nuclear magnetic resonance (NMR), isothermal titration calorimetry (ITC), and molecular simulation (MS) experiments were used, respectively, to determine the size and structure of the empty and drug-loaded nanomicelles (DLNMs), along with the interactions between the NMs and their cargoes. The in vitro release data revealed profiles governed by Fickian diffusion; moreover, for both anticancer molecules, an acidic environment (pH = 5.0) facilitated drug release with respect to physiological pH conditions (pH = 7.4). Finally, both DAB- and VEM-loaded NMs elicited enhanced response with respect to free drug treatments in 4 different melanoma cell lines

Angiogenesis

APJ has been extensively described in the pathophysiology of angiogenesis and cell proliferation. The prognostic value of APJ overexpression in many diseases is now established. This study aimed to design a PET radiotracer that specifically binds to APJ. Apelin-F13A-NODAGA (AP747) was synthesized and radiolabeled with gallium-68 ([Ga]Ga-AP747). Radiolabeling purity was excellent (> 95%) and stable up to 2 h. Affinity constant of [Ga]Ga-AP747 was measured on APJ-overexpressing colon adenocarcinoma cells and was in nanomolar range. Specificity of [Ga]Ga-AP747 for APJ was evaluated in vitro by autoradiography and in vivo by small animal PET/CT in both colon adenocarcinoma mouse model and Matrigel plug mouse model. Dynamic of [Ga]Ga-AP747 PET/CT biodistributions was realized on healthy mice and pigs for two hours, and quantification of signal in organs showed a suitable pharmacokinetic profile for PET imaging, largely excreted by urinary route. Matrigel mice and hindlimb ischemic mice were submitted to a 21-day longitudinal follow-up with [Ga]Ga-AP747 and [Ga]Ga-RGD small animal PET/CT. [Ga]Ga-AP747 PET signal in Matrigel was significantly more intense than that of [Ga]Ga-RGD. Revascularization of the ischemic hind limb was followed by LASER Doppler. In the hindlimb, [Ga]Ga-AP747 PET signal was more than twice higher than that of [Ga]Ga-RGD on day 7, and significantly superior over the 21-day follow-up. A significant, positive correlation was found between the [Ga]Ga-AP747 PET signal on day 7 and late hindlimb perfusion on day 21. We developed a new PET radiotracer that specifically binds to APJ, [Ga]Ga-AP747 that showed more efficient imaging properties than the most clinically advanced tracer of angiogenesis, [Ga]Ga-RGD.France Life Imagin

Self-assembling supramolecular dendrimer nanosystem for PET imaging of tumors

Bioimaging plays an important role in cancer diagnosis and treatment. However, imaging sensitivity and specificity still constitute key challenges. Nanotechnology-based imaging is particularly promising for overcoming these limitations because nanosized imaging agents can specifically home in on tumors via the "enhanced permeation and retention" (EPR) effect, thus resulting in enhanced imaging sensitivity and specificity. Here, we report an original nanosystem for positron emission tomography (PET) imaging based on an amphiphilic dendrimer, which bears multiple PET reporting units at the terminals. This dendrimer is able to self-assemble into small and uniform nanomicelles, which accumulate in tumors for effective PET imaging. Benefiting from the combined dendrimeric multivalence and EPR-mediated passive tumor targeting, this nanosystem demonstrates superior imaging sensitivity and specificity, with up to 14-fold increased PET signal ratios compared with the clinical gold reference 2-fluorodeoxyglucose ([18F]FDG). Most importantly, this dendrimer system can detect imaging-refractory low-glucose-uptake tumors that are otherwise undetectable using [18F]FDG. In addition, it is endowed with an excellent safety profile and favorable pharmacokinetics for PET imaging. Consequently, this dendrimer nanosystem constitutes an effective and promising approach for cancer imaging. Our study also demonstrates that nanotechnology based on self-assembling dendrimers provides a fresh perspective for biomedical imaging and cancer diagnosis

Structural characterisation of degradation products formed upon di-n-butyl phthalate radiolysis by high-performance liquid chromatography electrospray tandem mass spectrometry

International audienceStructural characterisation of 15 degradation products, formed upon di-n-butyl phthalate (DBP) radiolysis, has been achieved using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupling. The dissociation behaviour of protonated DBP was first established to be further used to characterise structural deviation in the degradation products. Based on accurate mass measurements, compounds shown by H PLC-MS analysis were all found to be DBP oxidation products, amongst which various sets of isomers could be distinguished. Collision-induced dissociation experiments performed on each electrosprayed molecule first allowed unambiguous definition of the location of the additional oxygen atoms; that is, in the alkyl branch or on the aromatic ring. Although location of the oxygen atom in the alkyl branches could not always be precisely determined, relative abundances of some product ions allowed oxygenated functions to be identifie

Self-assembling supramolecular dendrimers for biomedical applications: lessons learned from poly(amidoamine) dendrimers

International audienceDendrimers, notable for their well-defined radial structures with numerous terminal functionalities, hold great promise for biomedical applications such as drug delivery, diagnostics, and therapeutics. However, their translation into clinical use has been greatly impeded by their challenging stepwise synthesis and difficult purification.To circumvent these obstacles, we have pioneered a self-assembly approach to constructing noncovalent supramolecular dendrimers using small amphiphilic dendrimer building units which can be easily synthesized and purified. By virtue of their amphipathic nature, the small amphiphilic dendrimers are able to self-assemble and generate large supramolecular dendrimers via noncovalent weak interactions such as van der Waals forces, H bonds, and electrostatic interactions. The so-created noncovalent dendrimers can mimic covalent dendrimers not only in terms of the radial structural feature emanating from a central core but also in their capacity to deliver drugs and imaging agents for biomedical applications. The noncovalent supramolecular dendrimers can be easily synthesized and modulated with regard to size, shape, and properties by varying the nature of the hydrophobic and hydrophilic entities as well as the dendrimer generation and terminal functionalities, ensuring their adaptability to specific applications. In particular, the dendritic structure of the amphiphilic building units permits the creation of large void spaces within the formed supramolecular dendrimers for the physical encapsulation of drugs, while the large number of surface functionalities can be exploited for both physical and chemical conjugation of pharmaceutic agents for drug delivery.Poly(amidoamine) (PAMAM) dendrimers are the most intensively studied for biomedical applications by virtue of their excellent biocompatibility imparted by their peptide-mimicking amide backbones and numerous interior and terminal amine functionalities. We present a short overview of our self-assembly strategy for constructing supramolecular PAMAM dendrimers for biomedical applications. Specifically, we start with the introduction of dendrimers and their synthesis, focusing on the innovative self-assembly synthesis of supramolecular dendrimers. We then detail the representative examples of the noncovalent supramolecular PAMAM dendrimers established in our group for the delivery of anticancer drugs, nucleic acid therapeutics, and imaging agents, either within the dendrimer interior or at the dendrimer terminals on the surface. Some of the supramolecular dendrimer nanosystems exhibit outstanding performance, excelling the corresponding clinical anticancer therapeutics and imaging agents. This self-assembly approach to creating supramolecular dendrimers is completely novel in concept yet easy to implement in practice, offering a fresh perspective for exploiting the advantageous features of dendrimers in biomedical applications

First Phytochemical Profiling and <i>In-Vitro</i> Antiprotozoal Activity of Essential Oil and Extract of <i>Plagiochila porelloides</i>

Volatiles metabolites from the liverwort Plagiochila porelloides harvested in Corsica were investigated by chromatographic and spectroscopic methods. In addition to already reported constituents, three new compounds were isolated by preparative chromatography and their structures were elucidated by mass spectrometry (MS) and NMR experiments. Hence, an atypic aliphatic compound, named 1,2-dihydro-4,5-dehydronerolidol and two isomers, (E) and (Z), possessing an unusual humbertiane skeleton (called p-menth-1-en-3-[2-methylbut-1-enyl]-8-ol) are newly reported and fully characterized in this work. The in vitro antiprotozoal activity of essential oil and extract of P. porelloides against Trypanosoma brucei brucei and Leishmania mexicana mexicana and cytotoxicity were determined. Essential oil and Et2O extract showed a moderate activity against T. brucei with IC50 values: 2.03 and 5.18 μg/mL, respectively. It is noteworthy that only the essential oil showed a high selectivity (SI = 11.7). Diethyl oxide extract exhibited moderate anticancer (cancerous macrophage-like murine cells) activity and also cytotoxicity (human normal fibroblast) with IC50 values: 1.25 and 2.96 μg/mL, respectively

Suppressing background signals in solid state NMR via the Electronic Mixing-Mediated Annihilation (EMMA) method

International audienceA simple procedure to effectively suppress background signals arising from various probe head components (e.g. stator, rotors, inserts) in solid state NMR is presented. Similarly to the ERETIC (TM) method, which uses an electronic signal as an internal standard for quantification, the proposed scheme is based on an electronically generated time-dependent signal that is injected into the receiver coil of the NMR probe head during signal acquisition. More specifically, the line shape, width and frequency of this electronic signal are determined by deconvoluting the background signal in the frequency domain. This deconvoluted signal is then converted into a time-dependent function through inverse Fourier Transform, which is used to generate the shaped pulse that is fed into the receiver coil during the acquisition of the Free Induction Decay. The power of the shaped pulse is adjusted to match the intensity of the background signal, and its phase is shifted by 180 degrees with respect to the receiver reference phase. This so-called Electronic Mixing-Mediated Annihilation (EMMA) methodology is demonstrated here with a C-13 Single Pulse Magic Angle Spinning spectrum of an isotopically enriched C-13 histidine solid sample recorded under quantitative conditions. (C) 2012 Elsevier Inc. All rights reserved

New advances in the volatile metabolites of Frullania tamarisci

International audienceThe chemical composition of Frullania tamarisci essential oil from Corsica was investigated using GC-FID, GC-MS and NMR analyses. The essential oil compositions were further studied analyzing samples prepared from three different Corsican locations and during a seasonal vegetative cycle. 40 components, which accounted for 78.3-89.8% of the total amount of F. tamarisci essential oils were identified. The main components were tamariscol coeluted with pacifigorgiol (30.4-41.5%), germacra-1(10)E,5E-dien-11-ol (3.6-7.1%), gamma-cylocostunolide (1.8-20.1%), gamma-dihydrocyclocostunolide (1.2-8.0%) and frullanolide (1.7-4.9%). Among them, germacra-1(10)E,5E-dien-11-ol was never reported in the Frullania genus and pacifigorgiol, a tamariscol GC-overlapped compound, was for the first time reported in Bryophytes. Finally using 1D and 2D NMR experiments, we reported gamma-dihydrocyclocostunolide as a new natural compound. Two Corsican F. tamarisci essential oils with different GC profiles were assessed for their phytotoxic behavior against onion seeds and seedling in order to evaluate their capacity to inhibit germination and alter the development of plantlets. According to the essential oil-compositions, a stimulation of the onion seedling was observed when sesquiterpene lactones amount was higher, whilst the inhibition of roots growth occurs when sesquiterpene alcohols were predominantly