Véronique Barragan-Montero

Water-Dispersible Sugar-Coated Iron Oxide Nanoparticles. An Evaluation of their Relaxometric and Magnetic Hyperthermia Properties

Synthesis of functionalized magnetic nanoparticles (NPs) for biomedical applications represents a current challenge. In this paper we present the synthesis and characterization of water-dispersible sugar-coated iron oxide NPs specifically designed as magnetic fluid hyperthermia heat mediators and negative contrast agents for magnetic resonance imaging. In particular, the influence of the inorganic core size was investigated. To this end, iron oxide NPs with average size in the range of 4-35 nm were prepared by thermal decomposition of molecular precursors and then coated with organic ligands bearing a phosphonate group on one side and rhamnose, mannose, or ribose moieties on the other side. In this way a strong anchorage of the organic ligand on the inorganic surface was simply realized by ligand exchange, due to covalent bonding between the Fe(3+) atom and the phosphonate group. These synthesized nanoobjects can be fully dispersed in water forming colloids that are stable over very long periods. Mannose, ribose, and rhamnose were chosen to test the versatility of the method and also because these carbohydrates, in particular rhamnose, which is a substrate of skin lectin, confer targeting properties to the nanosystems. The magnetic, hyperthermal, and relaxometric properties of all the synthesized samples were investigated. Iron oxide NPs of ca. 16-18 nm were found to represent an efficient bifunctional targeting system for theranostic applications, as they have very good transverse relaxivity (three times larger than the best currently available commercial products) and large heat release upon application of radio frequency (RF) electromagnetic radiation with amplitude and frequency close to the human tolerance limit. The results have been rationalized on the basis of the magnetic properties of the investigated samples.

Carbonic Anhydrase Inhibitor Coated Gold Nanoparticles Selectively Inhibit the Tumor-Associated Isoform IX over the Cytosolic Isozymes I and II

An approach for the synthesis of carbonic anhydrase (CA, EC 4.2.1.1) inhibitor coated gold nanoparticles is reported. This nanomaterial selectively inhibited the tumor-associated isoform CA IX overexpressed in hypoxic cancers over the ubiquitous, cytosolic housekeeping isozymes CA I and II and was membrane impermeant. As CA IX has an extracellular active site, the new nanomaterial which is confined to the extracellular space may be useful for imaging and treatment of hypoxic tumors.

Water-Soluble Rhamnose-Coated Fe3O4 Nanoparticles

Water-soluble biocompatible rhamnose-coated Fe(3)O(4) nanoparticles of 4.0 nm are obtained by covalent anchorage of rhamnose on the nanoparticles surface via a phosphate linker. These nanoparticles present superparamagnetic behavior and nuclear relaxivities in the same order of magnitude as Endorem that make them potential magnetic resonance imaging (MRI) contrast agents of a second generation, where the saccharides represent also specific ligands able to target lectins on skin cells.

Fucans from a Tunisian brown seaweed Cystoseira barbata: Structural characteristics and antioxidant activity

Sulfated polysaccharides from brown seaweeds are known to be a topic of numerous studies, due to their beneficial biological properties including antioxidant activity. Fucans were isolated from the brown seaweed Cystoseira barbata harvested in Tunisia. ATR-FTIR and (1)H-NMR spectroscopies demonstrated that C. barbata sulfated polysaccharides (CBSPs) consisted mainly of 3-linked-α-l-fucopyranosyl backbone, acetylated and mostly sulfated at C-4. Molar degrees of sulfation and acetylation of CBSPs were 0.79 and 0.27, respectively. Neutral sugars analysis determined by gas chromatography-mass spectrometry (GC-MS) showed that CBSPs were mainly composed of fucose (44.6%) and galactose (34.32%) with few amounts of other sugars such as glucose (7.55%), rhamnose (6.41%), xylose (4.21%) and mannose (2.91%). CBSPs were examined for in vitro antioxidant properties using various antioxidant assays. CBSPs exhibited important DPPH radical-scavenging activity (100% inhibition at a concentration of 1.5mg/ml) and considerable ferric reducing potential (24.62 mg ascorbic acid equivalents). Effective chelating activity and significant protection activity against hydroxyl radical induced DNA breakage were also recorded for CBSPs. However, in the linoleate-β-carotene system, CBSPs exerted moderate antioxidant activity (62% inhibition at a concentration of 1.5mg/ml). Therefore, CBSPs can be used as a potent natural antioxidant in food industry or in the pharmaceutical field.

Carbonic anhydrase inhibitors : 2-Substituted-1.3,4-thiadiazole-5-sulfamides act as powerful and selective inhibitors of the mitochondrial isozymes VA and VB over the cytosolic and membrane-associated carbonic anhydrases I, II and IV

A series of 2-substituted-1,3,4-thiadiazole-5-sulfamides was prepared and assayed as inhibitors of several carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic CA I and II, the membrane-associated CA IV and the mitochondrial CA VA and VB. The new compounds showed weak inhibitory activity against hCA I (K(I)s of 102 nM-7.42 microM), hCA II (K(I)s of 0.54-7.42 microM) and hCA IV (K(I)s of 4.32-10.05 microM) but were low nanomolar inhibitors of hCA VA and hCA VB, with inhibition constants in the range of 4.2-32 nM and 1.3-74 nM, respectively. Furthermore, the selectivity ratios for inhibiting the mitochondrial enzymes over CA II were in the range of 67.5-415, making these sulfamides the first selective CA VA/VB inhibitors.

Synthesis of mannose-6-phosphate analogues and their utility as angiogenesis regulators.

Although carbohydrates are the most abundant natural products, their use as therapeutic agents has been limited. However, since carbohydrate binding proteins are involved in many biological processes, including cellular communication, the prospects for carbohydrate-based drugs seem bright. Here, we provide a synthetic route to bioactive mannose derivatives that serve as both positive and negative effectors of angiogenesis, thereby laying the groundwork for future drug development. The current, limited applications of carbohydrates as therapeutics may, in part, be related to the high complexity of interactions between carbohydrate and carbohydrate binding proteins. Carbohydrate oligomers are themselves complex; for example, four different monosaccharides can form 35 560 distinct tetrasaccharides—this large number reflects the multiple hydroxy attachment sites on each component sugar. Thus, a relatively small polysaccharide has an enormous capacity to encode biological information. When these polysaccharides are conjugated to proteins, the complexity further increases. To date, more than 80 carbohydrate binding proteins have been identified, and their binding specificities have been described (or are about to be). Among these proteins, the lectin family has been extensively studied and classified into subfamilies according to their cellular location and their carbohydrate binding specificities. For example, the P-type lectins recognize mannose-6-phosphate (M6P), the motivation behind efforts in the design and synthesis of new M6P analogues. P-type lectins encompass the 46 kD cation-dependent M6P receptor (CD-M6PR), the 300 kD cation-independent M6P receptor (CI-M6PR), and proteins harboring M6P homology domains. One major cellular function of the receptors is to help cargo M6P-containing proteins between various subcellular compartments. In addition, CI-M6PR is actually a large multipartner receptor. It binds insulin-like growth factor-2 (IGF-2) at the cell surface and internalizes this growth factor for degradation inside lyzozomes. The functions of other proteins harboring M6P residues are also dependent on their interactions with this receptor. For example, latent transforming growth factor-b (TGF-b) is converted into active TGF-b upon M6P interaction with the receptor. Leukemia inhibitory factor (LIF), a growth factor, is cleared from the extracellular medium via receptor interaction with M6P, and subsequent internalization prevents an excessive accumulation that is detrimental to health especially during development. Moreover, proliferindependent angiogenesis also requires CI-M6PR. The obvious importance of M6P in biological processes, including angiogenesis, prompted us to evaluate the activity of our new analogues in blood vessel formation. As will be shown, the analogues do indeed have substantial effect on angiogenesis. The monosaccharides synthesized and examined here include a variety of substituents at the mannose 6-position: azido (4), aminomethyl (6), carboxyl (7), malonate (8), sulfonate (9), carboxymethyl (10), and phosphonate (3). The replacement of the phosphate head group by other moieties, mostly bioisosteres of phosphate, are intended to provide enzymatically stable compounds that could be used as tools to better understand the chemical factors involved in the modulation of angiogenic activities. In the past, the development of carbohydrates for therapeutic purposes has been considered problematic due to the challenges in synthesizing carbohydrate mimics; however, recent progress in this area has allowed us to overcome these limitations. We now present a simple and efficient synthesis of seven M6P analogues using a cyclic sulfate intermediate. Current routes to M6P analogues exploit activating the C-6 position by a variety of methods, such as halogenation, sulfonation, epoxidation and the use of phosphonium salts followed by nucleophilic substitution. Homologation of mannose has been achieved previously by oxidation of the primary alcohol followed by a Wittig–Horner reaction on the resultant aldehyde. Recently, we introduced substitutions at the C-6 position of mannose via a Mitsunobu reaction. These approaches can be efficient, but a need for a more versatile method led us to access such compounds via the cyclic sulfate method previously developed by us to obtain, in just a few steps with the potential for scale-up, a wide variety of C-6 mannose derivatives (Scheme 1). Regioselective nucleophilic displacement of cyclic sulfate 2 is the key step to obtain all the described mannose derivatives. In the case of phosphonate 3, malonate 8, and sulfonate 9, the corresponding nucleophiles were prepared with the aid of a strong base such as n-butyllithium or sodium hydride. An [a] Dr. V. Barragan-Montero, A. Awwad, S. Combemale, Prof. J.-L. Montero Institut des Biomol!cules Max Mousseron (IBMM) UMR 5247 UM2-UM1-CNRS, ENSCM 8 rue de l’Ecole Normale, 34296 Montpellier cedex 5 (France) E-mail : veronique.montero@univ-montp2.fr [b] Dr. P. de Santa Barbara INSERM U1046, UM1 371 avenue du doyen G. Giraud, 34295 Montpellier Cedex 5, (France) [c] B. Jover CNRS-FRE3400 IURC, UM1 641 avenue du doyen G. Giraud, 34093 Montpellier Cedex 5 (France) [d] Dr. J.-P. Mols INSERM U1058, UM1, CHU Montpellier 15 avenue Charles Flahault, 34093 Montpellier Cedex 5 (France) E-mail : jean-pierre.moles@inserm.fr Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cmdc.201100293.

Gold Nanoparticles Decorated with Mannose-6-phosphate Analogues

Herein, the preparation of neoglycoconjugates bearing mannose-6-phosphate analogues is described by: (a) synthesis of a cyclic sulfate precursor to access the carbohydrate head-group by nucleophilic displacement with an appropriate nucleophile; (b) introduction of spacers on the mannose-6-phosphate analogues via Huisgen’s cycloaddition, the Julia reaction, or the thiol-ene reaction under ultrasound activation. With the resulting compounds in hand, gold nanoparticles could be functionalized with various carbohydrate derivatives (glycoconjugates) and then tested for angiogenic activity. It was observed that the length and flexibility of the spacer separating the sugar analogue from the nanoparticle have little influence on the biological response. One particular nanoparticle system substantially inhibits blood vessel growth in contrast to activation by the corresponding monomeric glycoconjugate, thereby demonstrating the importance of multivalency in angiogenic activity.

Polyphenolic-protein-polysaccharide ternary conjugates from Cystoseira barbata Tunisian seaweed as potential biopreservatives: Chemical, antioxidant and antimicrobial properties

The present study investigated the antioxidant and antimicrobial activities of naturally occurring Cystoseira barbata seaweed glyco-conjugates (CBGs), with a view to developing safer food preservatives. CBGs were successfully isolated, then chemically and structurally characterized. CBGs contained a high amount of polysaccharides (49.76%) that consisted mainly of neutral sugars (47.67%) and uronic acids (2.09%). The carbohydrate fraction was sulfated (13.81%) and conjugated with proteins (9.86%) and phenolic compounds (4.98%). Infrared spectroscopy of CBGs showed interactions between polyphenols, proteins and polysaccharides, which were characterized by α-type glycosidic bond and sulfate groups in the axial position of sugar residues. Neutral sugars analysis of CBGs by GC-MS revealed that conjugated polysaccharides were mainly composed of galactose (34.02%), fucose (26.25%) and mannitol (21.25%) with few amounts of other sugars such as glucose (5.78%), rhamnose (4.9%), xylose (3.22%) and mannose (2.22%). Analysis of the amino acid composition of CBGs showed a high level of essential amino acids (40.36%), in which threonine was the most relevant (10.28%). LC-QTOF-MS analysis of the phenolic fraction of CBGs showed a variety of phenolic compounds including flavonoids, phlorotannins and anthraquinone glycosides. CBGs exhibited potent antioxidant activities including radical scavenging activity, chelating ability and reducing power, and displayed noticeable antibacterial and antifungal activities, which may open the way to the development of a natural biopreservation strategy based on algae.

Some physicochemical characteristics of pinus (Pinus halepensis Mill., Pinus pinea L., Pinus pinaster and Pinus canariensis) seeds from North Algeria, their lipid profiles and volatile contents

Physicochemical characteristics of seeds of some pinus species (Pinus halepensis Mill., Pinus pinea L., Pinus pinaster and Pinus canariensis) grown in North Algeria were determined. The results showed that the seeds consist of 19.8-36.7% oil, 14.25-26.62% protein, 7.8-8.6% moisture. Phosphorus, potassium and magnesium were the predominant elements present in seeds. Pinus seeds oil physicochemical properties show acid values (4.9-68.9), iodine values (93.3-160.4) and saponification values (65.9-117.9). Oil analysis showed that the major unsaturated fatty acids for the four species were linoleic acid (30-59%) and oleic acid (17.4-34.6%), while the main saturated fatty acid was palmitic acid (5-29%). Gas Chromatography and Mass Spectrometry analysis of P. halepensis Mill., P. pinaster and P. canariensis volatile oils indicated that the major volatile compound was the limonene with relative percentage of 3.1, 7.5 and 10.8, respectively.

New mannose derivatives: The tetrazole analogue of mannose-6-phosphate as angiogenesis inhibitor

Two novel compounds with mannose-derived structure, bearing a tetrazole (compound 3) and a sulfone group (compound 4) in terminal position, have been prepared from methyl α-d-mannopyranoside in reduced number of steps. The angiogenic activity of 3 and 4 has been screened using the chick chorioallantoic membrane (CAM) method. Tetrazole 3 has been identified to possess a promising bioactivity, being identified as angiogenesis inhibitor, with 68% of neovascular vessels when compared to control (PBS).