Laboratory and Field Evaluation of Biodegradable Polyesters for Sustained Release of Isometamidium and Ethidium

An overview is presented of the results obtained with biodegradable sustained release devices (SRDs) containing a mixture of polymers and either isometamidium (ISMM) or ethidium. Under controlled laboratory conditions (monthly challenge with tsetse flies infected with Trypanosoma congolense) the protection period in SRD treated cattle could be extended by a factor 2.8 (for ethidium) up to 4.2 (for ISMM) as compared to animals treated intramuscularly with the same drugs. Using a competitive drug ELISA ISMM concentrations were detected up to 330 days after the implantation of the SRDs, whereas after i.m. injection the drug was no longer present three to four months post treatment. Two field trials carried out in Mali under heavy tsetse challenge showed that the cumulative infection rate was significantly lower in the ISMM-SRD implanted cattle than in those which received ISMM intramuscularly. Using ethidium SRD, however, contradictory results were obtained in field trials in Zambia and in Mali. The potential advantages and inconvenients of the use of SRDs are discussed and suggestions are made in order to further improve the currently available devices.

Additives and Protein-DNA Combinations Modulate the Humoral Immune Response Elicited by a Hepatitis C Virus Core-encoding Plasmid in Mice

Humoral and cellular immune responses are currently induced against hepatitis C virus (HCV) core following vaccination with core-encoding plasmids. However, the anti-core antibody response is frequently weak or transient. In this paper, we evaluated the effect of different additives and DNA-protein combinations on the anti-core antibody response. BALB/c mice were intramuscularly injected with an expression plasmid (pIDKCo), encoding a C-terminal truncated variant of the HCV core protein, alone or combined with CaCl2, PEG 6000, Freund's adjuvant, sonicated calf thymus DNA and a recombinant core protein (Co.120). Mixture of pIDKCo with PEG 6000 and Freund's adjuvant accelerated the development of the anti-core Ab response. Combination with PEG 6000 also induced a bias to IgG2a subclass predominance among anti-core antibodies. The kinetics, IgG2a/IgG1 ratio and epitope specificity of the anti-core antibody response elicited by Co.120 alone or combined with pIDKCo was different regarding that induced by the pIDKCo alone. Our data indicate that the antibody response induced following DNA immunization can be modified by formulation strategies.

Preservation of minimally processed 'aurora-1' peaches using additives

'Aurora-1' peaches establishes an interesting alternative as a minimally processed product, due to its characteristics like flavor, color, smell, and also because of its handling resistance. However, it has a short shelf life after a fresh-cut due to enzymatic browning and stone cavity collapse. The main purpose of this research was to test the additive with antioxidant effect to prevent browning in minimally processed 'Aurora-1' peaches. The minimal processing consists of washing, sanitizing, peelings and fruit stone extraction. After that, longitudinal cuts were made to obtain eight segments per fruit. The slices were immersed into the following treatment solutions: control (immersion in 2% ascorbic acid); 2% ascorbic acid + 2% calcium chloride; 1% sodium isoascorbate; 1% citric acid; 1% L-cysteine hydrochloride. The products were placed into rigid polystyrene trays branded MEIWA M-54, covered with 14 µm PVC film (OmnifilmTM) and kept in cold storage at 3ºC ± 2ºC and 65% RH for twelve days, and evaluated each three days. Appraised variables were appearance, soluble solids, titratable acidity, soluble carbohydrates and reducing sugars, total and soluble pectin, ascorbic acid, and peroxidase and polyphenol oxidase enzyme activity. L-cysteine gave to the minimally processed products a shelf life of twelve days, limmited by off-flavor. The treatment with ascorbic acid was efficient to maintainthe ascorbic acid content, with a shelf-life of nine days, limited by enzymatic browning.

Espectro infravermelho e análise conformacional do composto 3-fenil-2-oxo-1,2,3-oxatiazolidina

The infrared (IR) spectra of the four distict conformers located on the multidimensional potential energy surface (PES) for the 3-phenyl-1,2,3-oxathiazolidine 2-oxide compound have been calculated using the semiempirical quantum-mechanical method PM3. The band spectra are reported and compared directly with the experimental spectrum. The IR intensities are shown to be much more sensitive to conformational changes than the vibrational frequencies and so, the theoretical analysis of the IR spectrum can be used as a tool for helping in the elucidation of the structure of heterocyclic compounds.

Development and validation of a high performance liquid chromatographic method for determination of cyclosporine-A from biodegradable intraocular implants

An HPLC method was developed and validated aiming to quantify the cyclosporine-A incorporated into intraocular implants, released from them; and in direct contact with the degradation products of PLGA. The separation was carried out in isocratic mode using acetonitrile/water (70:30) as mobile phase, a C18 column at 80 ºC and UV detection at 210 nm. The method provided selectivity based on resolution among peaks. It was linear over the range of 2.5-40.0 µg/mL. The quantitation and detection limits were 0.8 and 1.2 µg/mL, respectively. The recovery was 101.8% and intra-day and inter-day precision was close to 2%.

Estudo comparativo da caracterização de filmes biodegradáveis de amido de mandioca contendo polpas de manga e de acerola

Most compounds reinforcements have been used to improve thermals, mechanical and barrier properties of biopolymers films, whose performance is usually poor when compared to those of synthetic polymers. Biodegradables films have been developed by adding mango and acerola pulps in different concentrations (0-17,1% w/w) as antioxidants active compounds to cassava starch based biodegradable films. The effect of pulps was studied in terms of tensile properties, water vapor permeability, DSC, among other analysis of the films. The study demonstrated that the properties of cassava starch biodegradable films can be significantly altered through of incorporation mango and acerola pulps.

Development and validation of a High Performance Liquid Chromatographic method for determination of etoposide in biodegradable polymeric implants

A method using HPLC-UV was developed and validated for the determination of etoposide incorporated into polycaprolactone implants. The method was carried out in isocratic mode using a C18 column (250 x 4.6 mm; 5 µm), at 25 ºC, with acetonitrile and acetic acid 4% (70:30) as mobile phase, a flow rate of 2 mL/min, and UV detection at 285 nm. The method was linear (r² > 0.99) over the range of 5 to 65 µg/mL, precise (RSD < 5%), accurate (recovery of 98.7%), robust, selective regarding excipient of the sample, and had a quantitation limit equal to 1.76 µg/mL. The validated method can be successfully employed for routine quality control analyses.

Use of new silica fillers as additives for polymers used in packaging of fruit

The objective of this work was to synthesize nanosilicas with different degree of hydrophobicity by the sol-gel method, using tetraethyl orthosilicate as a precursor. For this purpose, 3-aminopropyl triethoxysilane (APS) and 1,1,1,3,3,3 - hexamethyldisilazane (HMDS), were added during synthesis as modifiers. A commercial biopolymer (Hexamoll Dinch, BASF) intended for packaging of apples, was added to the new nanosilicas. The materials obtained were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, potentiometric titration, porosity, specific surface area and hydrophobicity/hydrophilicity by wetting test. Colorimetry was used to evaluate change in apple pulp color after contact with the different silicas.

Ultrafiltration membranes from waste polyethylene terephthalate and additives: synthesis and characterization

The synthesis and characterization of asymmetric ultrafiltration membranes from recycled polyethylene terephthalate (PET) and polyvinylpyrrolidone (PVP) is reported. PET is currently used in many applications, including the manufacture of bottles and tableware. Monomer extraction from waste PET is expensive, and this process has not yet been successfully demonstrated on a viable scale. Hence, any method to recycle or regenerate PET once it has been used is of significant importance from scientific and environmental research viewpoints. Such a process would be a green alternative due to reduced raw monomer consumption and the additional benefit of reduced manufacturing costs. The membranes described here were prepared by a phase-inversion process, which involved casting a solution containing PET, m-cresol as solvent, and polyethylene glycol (PEG) of different molecular weights as additives. The membranes were characterized in terms of pure water permeability (PWP), molecular weight cut-off (MWCO), and flux and membrane morphology. The results show that the addition of PEG with high molecular weights leads to membranes with higher PWP. The presence of additives affects surface roughness and membrane morphology.

Biodegradable nanoparticles obtained from zein as a drug delivery system for terpinen-4-ol

Biodegradable nanoparticles (NPs) have received considerable attention because of their possible use in the development of strategies for the topical delivery of oils and therapeutic drugs, particularly when drug penetration in dermis is desired. Zein is a prolamine and is a promising material for the design of drug delivery systems. In this study, NPs were prepared with zein and were used to encapsulate and release terpinen-4-ol, which is a therapeutic agent for the treatment of melanoma. The results show that the zein NPs are promising nanostructured systems for the prolonged delivery of T4OL with potential applications in anti-melanoma therapy.

Development and validation of a RP-HPLC method to determine the xanthyletin content in biodegradable polymeric nanoparticles

Xanthyletin is used as an inhibitor of the symbiotic fungus (Leucoagaricus gongylophorus) of the leaf-cutting ant (Atta sexdens rubropilosa), one of the most significant agricultural plague insects. The incorporation of this compound into nanoparticles is a promising approach to effectively control leaf-cutting ants. This study presents the development and validation of a specific analytical method using high-performance liquid chromatography (HPLC) for quantification of the xanthyletin content in biodegradable polymeric nanoparticles. The analytical methodology developed was specific, linear, accurate, precise, and robust. The absolute recovery of xanthyletin in colloidal suspensions was nearly 100%. The HPLC method proved reliable for the quantification of xanthyletin content in nanoparticle formulations.

Fotoquímica e fotofísica do ácido 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno

Este trabalho versa sobre a caracterização espectroscópica do ácido 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno, substância com potencialidade em complexação de íons metálicos. Para isto foram obtidos espectros de UV/VIS do composto em meio aquoso na presença e ausência de irradiação no ultra-violeta. Foram obtidos um coeficiente de extinção molar de 36.457 L mol-1 cm-1 e uma taxa de degradação de 5,2.10-7 mol L-1 min-1, quando se irradiou uma solução do composto cuja concentração era de 3,2.10-5 mol L-1 em uma cubeta de quartzo de 10mm de caminho ótico a 7,0cm de uma lâmpada de mercúrio de 80W.

Estudo do comportamento térmico dos compostos de Ag+ e Pb2+ com o ligante 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno

Este trabalho reporta o estudo de compostos binários do dicarboxilato 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno, C6H4(-CH=CH-CO-COO-)2 , com os cátions metálicos Ag+ e Pb2+, obtidos a partir de soluções aquosas do ligante e dos nitratos dos cátions metálicos, em proporções estequiométricas. Para a caracterização e o estudo do processo de decomposição térmica desses compostos foram empregadas Espectrofotometria de Absorção na Região do Infravermelho com Transformada de Fourier (FT-IR), Análise Elementar (C, H), Complexometria com EDTA, Termogravimetria (TG) e Calorimetria Exploratória Diferencial (DSC).

Analysis of the structural and electronic properties of 1-(5-Hydroxymethyl - 4 -[ 5 - (5-oxo-5-piperidin-1-yl-penta-1,3dienyl)-benzo[1,3]dioxol-2-yl] -tetrahydro-furan-2-yl)-5-methyl-1H-pyrimidine-2,4dione molecule

The structural and electronic properties of 1-(5-Hydroxymethyl - 4 -[ 5 - (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]-tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.