Study of Brea gum emulsifying properties for potential application on nanoencapsulation or controlled release of drug

VIRGINIA CASTEL; FEDERICO M. HARTE; LILIANA GABRIELA SANTIAGO; AMELIA CATALINA RUBIOLO; CARLOS CARRARA

Rosario

Encuentro; II Reunión Internacional de Ciencias Farmacéuticas (RICIFA); 2012

Facultad de Ciencias Bioquímicas y Farmacéuticas - Universidad Nacional de Rosario

Introduction Brea gum (BG) is a hydrocolloid obtained as an exudate from the Parkinsonia praecox tree (1) which consists in 83.77% polysaccharides and 7.5% proteins. Hydrocolloids are typically used not only as rheology control and suspending agents in liquid oral pharmaceutical formulations but also as structured carriers for controlled release and encapsulation applications. In this context, BG is a biopolymer that represents an interesting alternative to synthetic polymers as it is a biocompatible and biodegradable hydrocolloid. In particular, the ability of these carriers to entrap both hydrophilic and hydrophobic drugs might be very promising for many applications. In this contribution, we report experimental data on the optimization of the method to prepare biopolymers nanoparticles produced with BG. Materials and methods GB exudate nodules were collected from trees in Salta (Argentina) and kindly supplied by the promotion project of Brea as a non-wood forest product for the sustainable development of Wichí and Criollas communities of Chaco Salteño. The crude gum was purified by dissolution, centrifugation, filtration and freeze-drying steps. Nanoparticles were prepared by blending BG solution and pure corn oil. First, two emulsifying techniques were tested to blend pure corn oil with BG solutions: (i) Polytron homogenizer blending (Polytron, Kinematica, Bohemia, NY, USA) and (ii) Polytron homogenizer blending followed by an ultrasonic treatment (Ultrasound generator, Sonics and Materials VC-750, Newton, CT). Both, the influence of BG solution concentrations (2%, 5% and 10%) and BG solution/corn oil ratio (9:1 and 8:2) were analyzed at pH 4. Particle size distribution and particle average size were measured by a laser diffraction particle size analyzer (Beckman Coulter Delsa Nano C Particle Analyzer, Beckman Coulter, Inc., Fullerton, CA) just after preparation to evaluate emulsification effectiveness. Emulsion stabilities were evaluated by measuring the creaming destabilization in the Backscattering profile obtained with a Turbiscan Classic MA 2000 equipment (Formulation, Toulouse, France). Results The ultrasonic treatment added in method (ii) improved the emulsification effectiveness by decreasing the particle average size in 50%, obtaining nanosized particles (812.10 nm). So, method (ii) was then chosen to prepare emulsions in the following optimization experiments. 5% GB solution and 9:1 BG/oil ratio were the emulsifying conditions required to produce the smallest particle average size (626.93 nm). However, better emulsion stability was shown by 10% GB solution and 9:1 BG/oil ratio emulsions. The enhanced stability of the last system could be explained in terms of aqueous phase viscosity modification: an increment of BG concentration would increase system viscosity, thereby improving emulsion stability. Conclusions The results obtained from this study could be used in the design of BG nanoparticles as structured carriers for nano-encapsulation and controlled release of drugs. In these sense, BG presented significant surface activity at the oil–water interface showing interesting emulsifying properties in the formation and stabilization of nanoemulsions.