Vincent Lequart

Development of curcumin–cyclodextrin/cellulose nanocrystals complexes: New anticancer drug delivery systems

The synthesis of curcumin-cyclodextrin/cellulose nanocrystals (CNCx) nano complexes was performed. CNCx were functionalized by ionic association with cationic β-cyclodextrin (CD) and CD/CNCx complexes were used to encapsulate curcumin. Preliminary in vitro results showed that the resulting curcumin-CD/CNCx complexes exerted antiproliferative effect on colorectal and prostatic cancer cell lines, with IC50s lower than that of curcumin alone.

An Efficient Synthesis of New Spiro[indolo-3(1H),2’(3’H)-oxadiazolyl] and 1-(Triazol-4-ylmethyl)isatin Derivatives

The synthesis and the characterization of new isatin derivatives obtained by 1,3-dipolar cycloaddition reactions on allylisatin and propargylisatin are described. The products thus regiospecifically obtained in good yields bear oxadiazolyles or trizolyles groups, and were characterized by FT-IR spectroscopy, NMR spectroscopy and mass spectrometry.

Synthesis of peracetylated chacotriose

Steroidal glycoalkaloids of many Solanum species have recognized biological activities, especially those containing the glycosyl moiety alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)]-D-glucopyranose (chacotriose) whose peracetate is here synthesized and characterized by complete 1H and 13C NMR assignment.

Evidence of a self-inclusion phenomenon for a new class of mono-substituted alkylammonium-β-cyclodextrins

A new class of mono-substituted N-alkyl-N,N-dimethylammonium-beta-cyclodextrins has been synthesized in a three step procedure from the native beta-cyclodextrin. The structural analysis of these compounds undertaken by combined use of 1D and 2D NMR spectra indicate that the two methyl groups bound on the nitrogen are magnetically inequivalent due to a self-inclusion phenomenon of the alkyl chain inside the CD cavity. A variable-temperature 1H NMR study showed that these mono-substituted CD derivatives formed temperature-independent intramolecular complexes with their own alkylammonium substituent. The strength of the interaction between the alkyl moiety and the cyclodextrin cavity has been evaluated by a competitive method using an adamantane derivative. Finally, surface tension measurements demonstrated the surface active character of these compounds and confirmed their self-inclusion ability.

Structural reinvestigation of the core oligosaccharide of a mutant form of Aeromonas salmonicida lipopolysaccharide containing an O-4 phosphorylated and O-5 substituted Kdo reducing end group using electrospray quadrupole time of flight tandem mass spectrometry

The molecular structure of the mutant form of the lipopolysaccharide (LPS) of Aeromonas salmonicida was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group, and is proposed as the following: It was established that during the cleavage of this LPS with 1% acetic acid, to release the core oligosaccharide from the Lipid A portion, we obtained a degraded core oligosaccharide which eliminated its phosphate group with extreme ease. The precise molecular structure of this dephosphorylated core was deduced by electrospray mass spectrometry and is proposed as the following: Low-energy collision electrospray ionization quadrupole quadrupole time-of-flight tandem mass spectrometry (ESI-QqToF-MS/MS) analysis of the dephosphorylated core oligosaccharide confirmed the presence of the O-5 glycosylated 4,8- and 4,7-anhydro derivatives of the enolizable α-keto-acids. The collision-induced dissociation (CID) tandem mass spectrometric analysis of the heterogeneous mixture of the permethylated core oligosaccharide established the unreported methylation reaction on the diastereomeric 4,8- and 4,7-anhydro α-keto-acids and the complete permethylation and addition reaction of the O-5 glycosylated open chain reducing end terminal D-arabino-3-en-2-ulonic acid. The stereo-specific fragmentation routes obtained during the tandem mass spectrometric analysis permitted the precise sequencing of this dephosphorylated rough core oligosaccharide of the mutant LPS of A. salmonicida.

Synthesis and Amphiphilic Behavior of N,N‐Bis‐glucosyl‐1,5‐benzodiazepin‐2,4‐dione

Abstract Glucosyl‐1,5‐benzodiazepin‐2,4‐diones were synthesized in order to study the influence of the glucidic moiety on the amphiphilic behaviour. The glucosyl groups include 6‐deoxy‐D‐glucopyranos‐6‐yl and 6‐deoxy‐3‐O‐R‐D‐glucopyranos‐6‐yl (R = n − C n H 2n+1; n = 1, 8, 10 and 12). Variation in the length of the hydrocarbon chain allowed comparison of such amphiphilic data as water solubility (Sw) and surface tension (γ) values. At 25°C, the glucopyranosyl benzodiazepines with R = H and CH3 show a higher water solubility than the starting 1,5‐benzodiazepin‐2,4‐diones. Some other glucidic benzodiazepine derivatives with an appropriate alkyl chain at C‐3 carbon of the D‐glucopyranose present a variable hydrosolubility and surface tension γ values close to 43 to 46 mN · m−1 at the corresponding saturation. Moreover, according to preliminary tests, these compounds seem to show a better affinity for the blood brain barrier.

Enhancement of photobactericidal activity of chlorin-e6-cellulose nanocrystals by covalent attachment of polymyxin B

Despite the advances made over the last decade, infections caused by multi-drug resistant bacterial strains are increasingly important societal issues that need to be addressed. New approaches have already been developed in order to overcome this problem. Photodynamic antimicrobial chemotherapy (PACT) could provide an alternative to fight infectious bacteria. This approach has already inspired the development of innovative materials. Interesting results have been obtained against Gram-positive bacteria, but it also appeared that Gram-negative strains, especially Pseudomonas aeruginosa, were less sensitive to PACT. Enhanced efficacy against Gram-negative bacteria had been previously obtained with photosensitizers bound to antimicrobial peptides. In this work, we designed a photobactericidal organic material, CNCsc6-PMB, consisting of cellulose nanocrystals to which the photosensitizer chlorin-e6 and the antimicrobial polypeptide polymyxin B (PMB) were covalently attached. These modified nanocrystals were characterized by IR spectroscopy, zeta potential measurements and elemental analyses, after which antibacterial assays were carried out. Following light irradiation, CNCsc6-PMB demonstrated efficiency against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) by inhibition of bacterial growth. An amplifying effect of chlorin-e6 has been highlighted against these Gram-negative strains, based on membrane weakening and a potential docking effect from the polymyxin moiety. Such results confirmed the importance of using an antimicrobial peptide in order to broaden the spectrum of PACT.

2-[5-chloro(bromo)-3-hydrazono-2-oxo-2,3-dihydro-1H-indolin-1-yl]acetohydrazide

Isatin derivatives exhibit significant biological, medicinal and pharmacological activities, [1,2] such as antituberculous, antihypoxing agent, anticonvulsant, antihyperglycemic; active against salmonella, typhi and against vibrio cholerae. Besides, they are used in treating and preventing pestvirus.[...]

1-benzyl-3-(2-(pyridin-2-yl)hydrazono)indolin-2-one

1 Laboratoire de Chimie Organique Heterocyclique, Pole de competences Pharmacochimie UniversiteMohammed V-Agdal, BP: 1014 Avenue Ibn Batouta, Rabat, Morroco2 Blood-Brain Barrier Laboratory (EA 2465), IUT of Bethune, University of Artois, BP 819, F-62408Bethune*Author to whom correspondence should be addressed.. E-mail: emessassi@yahoo.fr

(4Z)-1-Benzyl (1,3-Dibenzyl)-4-(2-oxopropylidene)-1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one

We describe in this work the synthesis of new benzodiazepine derivatives susceptible to possess various pharmacological activities.[...]