Soraya Rodríguez-Rojo

Development of multicore hybrid particles for drug delivery through the precipitation of CO2 saturated emulsions.

Hybrid lipid-polymer particles are gaining increasing interest to be applied as drug delivery systems due to their greater stability in biological fluids and enhanced cellular uptake of drugs. However, a major drawback is the fact that these particles are usually produced through techniques that use organic solvents. This work studies the possibility of producing for the first time hybrid particles composed by lipid multicores enveloped in a polymeric layer through Particles from Gas Saturated Solutions (PGSS(®)), without using organic solvents. An oil-in-water emulsion, composed by Gelucire 43/01™ (GEL) as the discontinuous phase and by an aqueous polyethylene glycol 4000 (PEG) solution as the continuous phase, was successfully precipitated by PGSS(®). Operating conditions that ensured the stability of the CO2 saturated emulsion were previously evaluated. The resulting PEG-GEL particles present a spherical-like morphology constituted by several lipid cores encapsulated into a polymeric shell. The applicability of these structured particles to be used as drug delivery system (DDS) was studied by using ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID), as model drug. The particles provided an initial burst release of the drug due to the progressive dissolution of the external layer of PEG, followed by a controlled release of the NSAID from the GEL cores.

Using different natural origin carriers for development of epigallocatechin gallate (EGCG) solid formulations with improved antioxidant activity by PGSS-drying

Epigallocatechin gallate (EGCG) is the catechin with the highest antioxidant activity present in green tea. Nevertheless, due its low bioavailability, it is necessary to develop EGCG formulations capable of improving its stability resulting in increased bioavailability and thus higher biological activity of this catechin (e.g. antioxidant activity). The purpose of this work was the formulation of EGCG using three distinct natural origin carriers, namely OSA-starch, soybean lecithin and β-glucan, by particles from gas saturated solution drying (PGSS-drying). Non-cytotoxic solid formulations of EGCG in the range of micrometers and encapsulation efficiencies up to 80.5% were obtained. An improved antioxidant activity (AA) determined by the oxygen radical absorbance capacity (ORAC) method was obtained for all formulations. Furthermore, lecithin:EGCG and β-glucan:EGCG presented higher cellular antioxidant activity (Caco-2 cells) values than free EGCG at the same concentrations tested (around 1.5-fold higher values). Moreover, the solid formulations presented preservation of the AA over 4 months, and an improved storage stability in comparison with non-encapsulated EGCG over 48 h at 328 K in the absence of light (accelerated storage). These results show that PGSS-drying conditions enabled the preservation of the bioactive properties of catechin, allowing the formulation of solid particles with enhanced features.

Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity.

Phenolic characterization of aging wine lees: Correlation with antioxidant activities

Aging wine lees are water-wastes produced during the wine aging inside wood barrels that can be considered as alternative sources of bioactive compounds. Phenolic characterization and antioxidant activity (AA) measurements of wines lees solid-liquid extracts have been undertaken on a dry extract (DE) basis. Solvents with different polarities (water, methanol, ethanol, two hydroalcoholic mixtures and acetone) were used. Total phenolic (TPC) and total flavonoid contents (TFC) were determined. The mixture of 75:25(v/v) EtOH:H2O showed the highest values with 254 mgGAE/gDE and 146 mgCATE/gDE respectively. HORAC, HOSC and FRAP were used to determine the AA of the extracts being also highest for the mixture of 75:25(v/v) EtOH:H2O (4690 µmolCAE/gDE, 4527 µmolTE/gDE and 2197 µmolTE/gDE, respectively). For ORAC method, methanol extract showed the best value with 2771 µmolTE/gDE. Correlations between TPC, TFC, phenolic compounds and AA were determined. Most relevant compounds contributing to AA were identified using data from mass spectrometry, being mainly anthocyanins.

Barley and yeast β-glucans as new emulsifier agents for the development of aqueous natural antifungal formulations

Barley and yeast β-glucans were selected, together with lecithin, to encapsulate resveratrol by emulsification-evaporation method to develop new and safer antifungal formulations. Different emulsification techniques were used: high-shear, high pressure and high pressure and temperature emulsification. Morphology, crystallinity, encapsulation efficiency and in vitro antifungal activity against Botrytis cinerea of the different formulations were evaluated. No significant differences between each emulsification procedure in particle size (below 90nm) and in encapsulation efficiency (70-100%) were observed; only barley β-glucan emulsions showed lower efficiency due to the formation of a gel that retained most of the active compound. A great influence of the emulsification method and the encapsulating material on the crystallinity of the particles was observed. The highest antifungal activity (up to 53% growth inhibition) was obtained by the formulations with yeast β-glucans, indicating an enhanced absorption of encapsulated resveratrol through the cell wall of the fungus at the presence of (1-3, 1-6)-β-glucans.

CHAPTER 8:Post‐extraction Processes: Improvement of Functional Characteristics of Extracts

The biological activity of natural extracts is not determined only by their chemical composition. Other parameters, such as the physical parameters of the product (particle size and morphology, crystalline/amorphous structure) as well as the combination of the active extract with carriers or co‐active materials, also play a major role. With this perspective, post‐extraction and formulation methods are described in this chapter. Elimination of residual solvents and other contaminants as required by the regulations for commercialization is discussed first. Particle reduction techniques are presented next, which are essential both for obtaining a desired product size and morphology, as well as for increasing the bioavailability of active compounds with limited solubility in water. Formulation processes, which are used to protect sensitive active compounds, or for providing additional functionalities to the product, are also presented. Finally, the formulation of a β‐carotene extract for application as a natural colorant in foods and beverages is presented as a case study. The techniques discussed include top‐down milling and homogenization processes, and bottom‐up crystallization, emulsion‐template, spray‐drying and supercritical fluid processes, for the production of micro‐ or nanoparticles, microcapsules or microcomposites, as well as multifunctional nanocarriers such as micelles or liposomes.

Microwave and ultrasound pre-treatments to enhance anthocyanins extraction from different wine lees

Wine lees are rich in anthocyanins (AC), natural colorants with health promoting properties. The extraction kinetics of AC from different wine lees in conventional solid-liquid extraction were studied for the first time. The influence of parameters such as temperature, solid-liquid ratio (RS-L) and type of solvent (hydro-alcoholic mixtures) was also studied. Furthermore, microwaves (MW) and ultrasounds (US) were used as pre-treatments (a prior step to the conventional extraction) in order to increase AC yield. Maximum extraction yield (2.78 mgMALVIDIN-EQUIVALENTS/gDRY-LEES) was achieved after 15 min at 25 °C, with a RS-L of 1/10 (g/mL) and with a 50%vol. ethanol mixture. When MW were used AC extraction yield was doubled (6.20 mgMALVIDIN-EQUIVALENTS/gDRY-LEES) and the required time to achieve a constant yield was reduced (from 15 min to 90 s). Meanwhile, US only shortened extraction time in less proportion (from 15 to 5 min). Putative identification of main extract compounds was performed by LC/MS-MS.