Browsing by Author "Fernandez, Marcos"

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    Chemical characterization and microencapsulation of extracellular fungal pigments
    (2022) Contreras-Machuca, Paulina I.; Avello, Marcia; Pastene, Edgar; Machuca, Angela; Aranda, Mario; Hernandez, Vicente; Fernandez, Marcos
    In this work, extracellular colored metabolites obtained from the filamentous fungi Talaromyces australis and Penicillium murcianum, isolated in the Andean-Patagonian native forests of Chile, were studied as prospect compounds to increase the sustainability of cosmetic products. The chemical and antioxidant properties of these natural pigments were characterized and strategies for their microencapsulation were also studied. UHPLC/MS-MS analyses indicated that the predominant metabolites detected in the cultures of P. murcianum were monascin (m/z = 411.15) and monashexenone (m/z = 319.10), while athrorosin H (m/z = 458.20) and damnacanthal (m/z = 281.05) were detected in cultures of T. australis. ORAC tests revealed that P. murcianum's metabolites had the greatest antioxidant properties with values higher than 2000 mu mol of trolox equivalents/g. The fungal metabolites were successfully microencapsulated by ionic gelation into structures made of 1.3% sodium alginate, 0.2% chitosan, and 0.07% hyaluronic acid. The microencapsulation process generated structures of 543.57 +/- 0.13 mu m of mean diameter (d(50)) with an efficiency of 30% for P. murcianum, and 329.59 +/- 0.15 mu m of mean diameter (d(50)) and 40% efficiency, for T. australis. The chemical and biological characterization show the biotechnological potential of these fungal species to obtain pigments with antioxidant activity that could be useful in the cosmetic industry. The encapsulation process enables the production of easy-to-handle dry powder from the fungal metabolites, which could be potentially marketed as a functional cosmetic ingredient.
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    Impact of molecular weight and deacetylation degree of chitosan on the bioaccessibility of quercetin encapsulated in alginate/chitosan-coated zein nanoparticles
    (2023) Carrasco-Sandoval, Jonathan; Aranda, Mario; Henriquez-Aedo, Karem; Fernandez, Marcos; Lopez-Rubio, Amparo; Fabra, Maria Jose
    This work aimed at studying the effect of molecular weight (MW) and deacetylation degree (DD) of chitosan on the quercetin bioaccessibility encapsulated in alginate/chitosan-coated zein nanoparticles (alg/chiZN). The chitosan coating layer produced nanoparticulate systems with good stability parameters, high encapsulation efficiency (EE) and a higher bioaccessibilty of quercetin after in-vitro digestion. By increasing the DD of chitosan, the zeta-potential of the colloidal system significantly increased (>= 27.1 mV), while low and very low MW chitosans generated systems with smaller particle sizes (<= 277.8 nm) and polydispersity index [PDI (0.189)]. The best results, in terms of EE (>= 84.44) and bioaccessibility (>= 76.70), were obtained when the systems were prepared with low MW chitosan and high DD. Thus, the alg/chiZN nanocapsules may be a promising delivery system for improving the quercetin bioaccessibility or other compounds with a similar chemical nature, especially when higher DD and lower MWs are used.
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    Optimization of detergents in solubilization and reconstitution of Aquaporin Z: A structural approach
    (2023) Beratto-Ramos, Angelo; Dagnino-Leone, Jorge; Martinez-Oyanedel, Jose; Fernandez, Marcos; Aranda, Mario; Borquez, Rodrigo
    Background: The exceptional capacities of aquaporins in terms of water permeation and selectivity have made them an interesting system for membrane applications. Despite the multiple attempts for immobilizing the aquaporins over a porous substrate, there is a lack of studies related to the purification and reconstitution steps, principally associated with the use of detergents in solubilization and destabilization steps. This study analyzed the effect of detergents in Aquaporin Z solubilization, considering the purity and structural homogeneity of the protein.Methods: The extraction process was optimized by the addition of detergent at the sonication step, which enabled the omission of the ultracentrifugation and resuspension steps. Two detergents, Triton X-100, and octyl-glucoside were also evaluated. Destabilization mediated by detergents was used as reconstitution method. Saturation and solubilization points were defined by detergent concentration and both, liposomes and proteoliposomes, were analyzed by size distribution and permeability assays. Detergent removal with Bio-beads was also analyzed.Results: Octyl glucoside ensures structural stability and homogeneity of Aquaporin Z. However, high concen-trations of detergents induce the presence of defects in proteoliposomes. While saturated liposomes create ho-mogeneous and functional structures, solubilized liposomes get affected by a reassembly process, creating vesicle defects with anomalous permeability profiles.Conclusions: Detergent concentration affects the structural conformation of proteoliposomes in the reconstitution process. General significance: Since the destabilization process is dependent on vesicle, detergent, and buffer composition, optimization of this process should be mandatory for further studies. All these considerations will allow achieving the potential of Aquaporins and any other integral membrane protein in their applications for in-dustrial purposes.