Elquio Eleamen Oliveira

Xylan from corn cobs, a promising polymer for drug delivery: Production and characterization

Although many authors have reported several beneficial effects ascribed to xylan, such as inhibitory action on mutagenicity activity, antiphlogistic effects, and mitogenic and comitogenic activities, few papers have investigated a systematic study on the technological properties of this polymer. The aim of the present work was to evaluate xylan as a promise raw material for the pharmaceutical industry. The water-insoluble xylan samples were extracted from corn cobs following several steps. The obtained powered sample was analyzed by infrared and RMN spectroscopy, and characterized regarding their particle size, bulk and tap densities, compressibility index, compactability, Hausner ratio, and angle of repose. According to the results, infrared and RMN spectroscopy were shown to be able to evaluate the xylan structural conformation and composition, respectively. In addition, rheological data demonstrated that xylan powder obtained from corn cobs may be characterized as a material with low density and very cohesive flow properties.

Development and Evaluation of Emulsions from Carapa guianensis (Andiroba) Oil

Carapa guianensis, a popular medicinal plant known as “Andiroba” in Brazil, has been used in traditional medicine as an insect repellent and anti-inflammatory product. Additionally, this seed oil has been reported in the literature as a repellent against Aedes aegypti. The aim of this work is to report on the emulsification of vegetable oils such as “Andiroba” oil by using a blend of nonionic surfactants (Span 80® and Tween 20®), using the critical hydrophilic–lipophilic balance (HLB) and pseudo-ternary diagram as tools to evaluate the system’s stability. The emulsions were prepared by the inverse phase method. Several formulations were made according to a HLB spreadsheet design (from 4.3 to 16.7), and the products were stored at 25°C and 4°C. The emulsion stabilities were tested both long- and short-term, and the more stable one was used for the pseudo-ternary diagram study. The emulsions were successfully obtained by a couple of surfactants, and the HLB analysis showed that the required HLB of the oil was 16.7. To conclude, the pseudo-ternary diagram identified several characteristic regions such as emulsion, micro-emulsion, and separation of phases.

Influence of the Lipophilic External Phase Composition on the Preparation and Characterization of Xylan Microcapsules—A Technical Note

Scientific studies on new drug delivery systems have significantly increased in the past few years and this growth is expected to continue in the near future (1). Such systems are of great interest because of their ability to improve drug performance in terms of efficacy, safety, and patient compliance (1). In many cases, conventional drug delivery provides an increase of drug concentration at potentially toxic levels (2). Additionally, the need for delivering drugs with fewer side effects has prompted the development of new drug delivery systems (1). Xylan is the second most abundant polymer found in hardwoods and annual plants (3), particularly in agricultural residues such as grain hulls, corn cobs, and corn stalks (4). Depending on the botanical source, the backbone chemical structure may vary. However, the majority of xylans present side chains of different sugars such as 4-O-methyl-d-glucoronic acid, O-acetyl-l-arabinose, l-arabinose, and d-glucoronic acid bond by a glycosidic linkage to the backbone (3). Because of its complex structure, the complete degradation of xylan requires the activity of several enzymes which are specifically produced by human colonic microflora (5). Therefore, xylan microcapsules may represent a novel and promising colon-specific drug delivery system. Microcapsules based on natural polymers may be produced by means of a variety of methods. Emulsion solvent extraction, emulsion solvent evaporation and interfacial cross-linking polymerization are the most commonly employed processes for the production of microcapsules (4). One of the critical parameters in the microencapsulation process is the external phase used in the emulsification step (6). In fact, the external phase can influence the microcapsules morphology, their aggregation state, and mainly the release of the microencapsulated active compound (7). Because the production of xylan-based microcapsules is a subject barely studied by scientists worldwide, the aim of this work was to evaluate the influence of the lipophilic external phase composition on the production and mean particle size of xylan microcapsules produced by interfacial cross-linking polymerization.

Xylan, a Promising Hemicellulose for Pharmaceutical Use

Polymers are versatile materials with wide use in several industry fields, such as engineering, textile, automobile, packaging and biomedical. In the pharmaceutical industry, both natural and synthetic polymers have been largely used with different applications for the development and production of cosmetics and traditional dosage forms and novel drug delivery systems. For instance, a number of polymers are used as fillers, lubricants, disintegrants, binders, glidants, solubilizers, and stabilizers in tablets, capsules, creams, suspensions or solutions. Additionally, biodegradable and bioadhesive polymers may play an important role in the development of novel drug delivery systems, especially for controlled drug release.

Producing xylan/Eudragit® S100-based microparticles by chemical and physico-mechanical approaches as carriers for 5-aminosalicylic acid

Abstract Xylan is a biopolymer found in a variety of cell wall plants. Eudragit® S-100 (ES100), a pH-dependent polymer, is used as a coating material in gastroresistant delivery systems. In this study, microparticles based on both polymers were produced by interfacial cross-linking polymerisation and/or spray-drying technique in order to investigate feasibility and stability of the systems. Size and morphology of the microparticles were characterised by optical and SEM while FT-IR, thermal analysis (TG/DTA), and X-ray diffraction (XRD) evaluated the drug–polymer interactions and the thermal behaviour of the systems. FT-IR confirmed the absence of chemical interaction between the polymers. TG/DTA analysis showed a higher stability for spray-dried microparticles and XRD data proved the amorphous feature of both carriers. The results reveal that xylan/ES100 microparticles can be produced by chemical or physico-mechanical ways, the latter being the best option due to the lack of toxic cross-linking agents and easy scale-up.

Preparation and characterization of safe microparticles based on xylan

Abstract This work describes the preparation and evaluation of safe xylan-based microparticles prepared by cross-linking polymerization using sodium trimetaphosphate. The resulting microparticles were evaluated for morphology, particle size, polymer-cross-link agent interaction, and in vitro toxicity. The microparticles showed narrow monodisperse size distributions with their mean sizes being between 3.5 and 12.5 µm in dried state. FT-IR analyzes confirmed the interaction between sodium trimetaphosphate and xylan during the cross-linking process with formation of phosphate ester bonds. Additionally, the X-ray diffraction patterns and FT-IR analyzes suggested that little or no cross-linking agent remained inside the microparticles. Furthermore, the in-vitro studies using Artemia salina and human erythrocytes revealed that the microparticles are not toxic. Therefore, the overall results suggest that these xylan microparticles can be used as a platform for new drug delivery system.

Desenvolvimento de biofilmes à base de xilana e xilana/gelatina para produção de embalagens biodegradáveis

O objetivo deste trabalho foi desenvolver e caracterizar filmes biodegradaveis a base de xilana extraida de sabugo de milho com potencial uso como uma nova materia-prima para embalagens biodegradaveis. Para tanto, os filmes foram produzidos atraves da secagem das dispersoes filmogenicas com diferentes concentracoes de xilana (150 mg, 300 mg, 600 mg), e glicerol (5%, 10%, 15%), com ou sem adicao de gelatina (1000 mg). A caracterizacao avaliou a morfologia, espessura, solubilidade, biodegradabilidade e opacidade. Os filmes com melhores propriedades foram testados como biocobertura em uvas ‘Italia’ em duas condicoes de temperatura: ambiente (25 °C) e refrigerada (4 °C). Os parâmetros de perda de massa e acidez objetivaram avaliar sua eficacia. Os resultados mostraram que os filmes a base de xilana/gelatina apresentaram os melhores aspectos macroscopicos. Alem disso, o aumento da concentracao de xilana fez decrescer sua solubilidade. Conclui-se que a eficacia dos filmes como bioembalagem foi dependente da concentracao de xilana na formulacao e do periodo de avaliacao.

Technological evaluation of emulsions containing the volatile oil from leaves of Plectranthus Amboinicus Lour

Background: Plectranthus amboinicus Lour is a species which is widespread throughout tropical countries where it is widely used against respiratory tract disorders such as bronchodilator, antitussive, and expectorant conditions. Objective: This study aims to characterize the essential oil of P. amboinicus (PaEO) and produce and evaluate emulsions containing PaEO. Materials and Methods: The essential oil was characterized by physical-chemical analyses for density, refractive index, 90% ethanol solubility, color, appearance, and identification by gas chromatography coupled to mass spectrometry detection. The emulsions were prepared following a hydrophile-lipophile balance [HLB] spreadsheet design from two nonionic surfactants (Span 80® and Tween 20®) producing HLB values ranging from 4.3 to 16.7. The products were stored at room temperature at 5°C. The emulsion stabilities were tested both in the long and short-term.Results: The PaEO was obtained by steam distillation and the total extraction was reached after 3 hours yielding of 0.2% (w/w). This essential oil was characterized by physicochemical analyses for density [1.5 g.ml-1], refraction index [0.9167], ethanol 90% solubility [1:2], color, and appearance (yellow/clear). Nineteen components were identified in the oil, among them the sesquiterpenes: carvacrol [33.50%], p-cymene [28.20%] and γ-terpinene [14.77%]. The emulsions obtained successfully showed, for the first time, HLB values for essential oils from Plectranthus amboinicus [15.7].Conclusion: The experimental data shows a relationship between HLB values of the surfactant mixtures contributing to the emulsified systems production containing phytopharmaceuticals. Such an approach is of great importance to the development of lipid carriers for therapeutic drugs. Abbreviations used: PaEO: essential oil of P. amboinicus, HLB: hydrophilic-lipophilic balance, CI: Creaming Index, MET: micro-emultocrit technique