Browsing by Author "Pastene, Edgar"

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    Amplification of the antioxidant properties of myricetin, fisetin, and morin following their oxidation
    (2024) Arias-Sante, M. Fernanda; Fuentes, Jocelyn; Ojeda, Camila; Aranda, Mario; Pastene, Edgar; Speisky, Hernan
    Quercetin oxidation leads to the formation of a metabolite, 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)benzofuranone, whose antioxidant potency was recently reported to be a 1000-fold higher than that of its precursor. The formation of similar metabolites (BZF) is limited to certain flavonols (FL), among which are myricetin, fisetin, and morin. Here we addressed the consequences of inducing the auto-oxidation of these flavonols in terms of their antioxidant properties (assessed in ROS-exposed Caco-2 cells). The mixtures that result from their oxidation (FLox) exhibited antioxidant activities 10-to-50-fold higher than those of their precursors. Such amplification was fully attributable to the presence of BZF in each FLox (established by HPLC-ESI-MS/MS and chemical subtraction techniques). An identical amplification was also found when the antioxidant activities of BZF, isolated from each FLox, and FL were compared. These findings warrant the search of these BZF in edible plants and their subsequent evaluation as a new type of functional food ingredients.
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    Antioxidant polyphenols extracted from Avocado epicarp (Persea americana var. Hass) inhibit Helicobacter pylori urease
    (2011) Chavez, Felipe; Aranda Bustos, Mario Antonio; Garcia, Apolinaria; Pastene, Edgar
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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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    Cu(I)-glutathione complex: A potential source of superoxide radicals generation
    (2008) Speisky, Hernán; Gomez, Maritza; Carrasco-Pozo, Catalina; Pastene, Edgar; López Alarcón, Camilo Ignacio; Olea-Azar, Claudio