Marcel Popa

Synthesis and Biological Activity of Some New 1,3,4-Thiadiazole and 1,2,4-Triazole Compounds Containing a Phenylalanine Moiety

New 1,3,4-thiadiazole, 6, 7 and 1,2,4-triazole derivatives, 8, 9 containing a phenylalanine moiety have been synthesized by intramolecular cyclization of 1,4-disubstituted thiosemicarbazides, 4, 5, in acid and alkaline media, respectively; the thiosemicarbazides were obtained by reaction of hydrazide 3 with appropriate aromatic isothiocyanates. The toxicity of the synthesized compounds was evaluated and the anti-inflammatory study of the triazole compound 9 established an appreciable anti-inflammatory activity that is comparable with that of other nonsteroidal anti-inflammatory agents.

Synthesis and Antimicrobial Activity of Some New 1,3,4-Thiadiazole and 1,2,4-Triazole Compounds Having a D,L-Methionine Moiety

New 1,3,4-thiadiazole, 5a-e, and 1,2,4-triazolecompounds 6a-c, containing a D,L-methionine moiety were synthesized by intramolecular cyclization of 1,4-disubstituted thiosemicarbazides 4a-e in acid and alkaline media, respectively. The potential antimicrobial effects of the synthesized compounds were investigated using the Staphylococcus aureus ATCC 25923, Bacillus antracis ATCC 8705, Bacillus cereus ATCC 10987, Sarcina lutea ATCC 9341 and Escherichia coli ATCC 25922 strains. The newly synthesized compounds exhibited promising activities against Bacillus antracis and Bacillus cereus.

Chemical functionalization of hyaluronic acid for drug delivery applications

Functionalized hyaluronic acid (HA) derivatives were obtained by ring opening mechanism of maleic anhydride (MA). FTIR and H(1) NMR spectroscopy were used to confirm the chemical linkage of MA on the hyaluronic acid chains. Thermal analysis (TG-DTG and DSC) and GPC data for the new products revealed the formation of new functional groups, without significant changes in molecular weight and thermal stability. New gels based on hyaluronic acid modified derivatives were obtained by acrylic acid copolymerization in the presence of a redox initiation system. The resulted circular and interconnected pores of the gels were visualized by SEM. The release profiles of an ophthalmic model drug, pilocarpine from tested gels were studied in simulated media. Evaluation of the cytotoxicity and cell proliferation properties indicates the potential of the new systems to be used in contact with biological media in drug delivery applications.

Double Cross-linked Chitosan—Gelatin Particulate Systems for Ophthalmic Applications

Gelatin/chitosan particles suitable for application in ocular drug administration were prepared by a two-step cross-linking process performed in an emulsion-phase separation system. The particles were characterized by scanning electron microscopy and laser diffractometry, and the diameters were 0.202—4.596 µm. The microparticles pH-dependent behavior was monitored by their mean diameter changes in aqueous environment. Adrenalin was drug used to study loading and release characteristics. The prepared particles were nontoxic, with the DL50 values of 6.9—8.19 g/kg body mass. The in vivo biocompatibility tests consisted of subcutaneous administration of a microparticle suspension in physiological serum followed by morpho histological analysis of the implantation site. The in vivo adrenalin ocular delivery was tested on both animals and a voluntary human patient to determine the adrenalin action and by tears. The particles showed good adherent properties without irritation to the patient; adrenalin was released cleared the ocular congestion.

Synthetic sialic-acid-containing polyvalent antiviral inhibitors

This review gives a brief survey of synthetic inhibitors of influenza virus which have been synthesized to date. It starts with a short introduction which describes the structure and mechanism of action of influenza virus and continues with the main research directions that have been used in order to inhibit the virus. This is followed by discussion of various synthetic materials, including synthesis and antiviral properties, which that have been tested against influenza virus. The most potent inhibitory compounds proved to be polyvalent, because of their high binding affinity and steric stabilization. Finally we conclude with a brief discussion on structural characteristics, a summary, and outlook overview.

Hydrogels Based on Carboxymethylcellulose and Gelatin for Inclusion and Release of Chloramphenicol

Hydrogels based on carboxymethylcellulose (CMC) and gelatin (GEL) crosslinked with glutaraldehyde were used to obtain interpenetrated— interconnecting polymer networks. They are designed to obtain controlled release polymeric drug systems. CMC and GEL were chosen for their biocompatibility and nontoxicity, which are compulsory conditions for polymers used in biomedical applications. By modifying the parameters of the crosslinking reaction, the obtained networks presented different crosslinking degrees and hence different swelling capacities. These properties determined the quantity of drug able to be loaded (0.25 g per gram of hydrogel). We obtained systems for which biologically active matter release was controlled by diffusion. The kinetics were zero-order during the major part of release period (∼500 min). These systems improve the bactericide activity compared with free drugs.

Double crosslinked interpenetrated network in nanoparticle form for drug targeting—Preparation, characterization and biodistribution studies

The development of polymer nanosystems able to target and control/sustain the drug delivery is still considered an important desideratum in pharmaceutical research. The present study reports the preparation of nanoparticles based on chitosan and gelatin, using a reverse emulsion-double crosslinking (ionic followed by covalent one) technique. The nanoparticles structural and morphological characteristics (diameter and size distribution), their swelling capacity in aqueous media of different pH (4 and 7.4) and their ability to include and release poorly water-soluble drugs were seen to be influenced by the composition of the polymer mixture and by the surfactants concentration. Also, nanoparticles biodistribution after intraperitoneal or intravenous administration was evaluated by polymer marking with fluorescein. Particles ability to penetrate different organs (liver, heart, lungs, and less brain, gums, testicles) was increased when injected intravenously.

Review : Polymeric Biomaterials As Enzyme and Drug Carriers Part IV: Polymeric Drug Carrier Systems

Oligomeres avec fonctions de liaison a une ou aux deux extremites, polymeres vecteurs de medicament.

Mechanical Properties and Weathering Behavior of Polypropylene-Hemp Shives Composites

This paper presents the obtaining and the characterization of composites with polypropylene matrix and hemp shives as filler in different ratios and containing poly(propylene)-co maleic anhydride (MAH-PP) 3% wt as compatibility agent. The weathering behavior of the composite enclosing 60% hemp shives, performed after the exposure to UV radiations at different exposure times, was evaluated. The changes in the chemical and morphological structures were investigated by FT-IR and RAMAN spectroscopies and AFM microscopy. The mechanical characteristics of the composites were determined before and after an artificial aging process, and they are within the limits of the values reported for polyolefin-based composites and materials with natural fillers. During the accelerated weathering process, the correlation between the chemical degradation of the main components of the composite and the modification of the mechanical properties after the process of aging has been observed.

Toward tunable amphiphilic copolymers via CuAAC click chemistry of oligocaprolactones onto starch backbone

Starch-based tunable amphiphilic copolymers are easily obtained by grafting polycaprolactone chains via 1,3 dipolar Copper-Catalyzed Azide-Alkyne Cycloaddition (click chemistry CuAAC), starting from propargylated starch and azido oligocaprolactones with different chain lengths as the precursors. The copolymers are characterized by (1)H and (13)C NMR, from which a degree of substitution of starch can tentatively be deduced. Besides these bulk characterizations, the surface of the functionalized starch is also characterized by XPS which confirms the triazole formation, particularly through the deconvolution of the N 1s peak, and by ToF-SIMS which, not only confirms the surface modification, but also highlights the disappearance of the Cu(+) cations. The solubility and swelling behaviours of these copolymers have been investigated, which clearly show the dependence both on the solvent and the PCL chain length. These investigations highlight the swelling dependence on the δd component of the Hansen solubility parameter of solvents. Finally, at low concentration, they present the capacity to organize themselves in aggregates in aqueous solutions, as seen from TEM and DLS investigations.