Examinando por Autor "ESPINOZA, LUIS"

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    Ítem
    ANTIOXIDANT AND TOXICITY ACTIVITY IN VITRO OF TWELVE SAFROLE DERIVATIVES
    (Sociedad Chilena de Química, 2014-09) MADRID, ALEJANDRO; ESPINOZA, LUIS; PAVÉZ, CATALINA; CARRASCO, HÉCTOR; HIDALGO, MARÍA ELIANA
    The aim of this study was to determine the influence of substituents in aromatic ring and the side chain of safrole on the antioxidant capacity and toxicity of twelve synthetic derivatives of safrole (S1-S12). Each compound was analyzed by two antioxidant methods: DPPH and bleaching of β-carotene (DBC). Among the derivates of safrol assayed, S5, S6, S9, S10 and S11 showed the strongest antioxidant capacity: DPPH method, first order specific rate constant (0.0152, 0.0211, 0.0432, 0.0317 and 0.0072) and DBC (22.41 ± 0.13%, 10.71 ± 0.05 %, 9.12 ± 0.89 %, 30.97 ± 0.92 % and 19.08 ± 0.31 %), respectively. The toxicity of the active compounds was evaluated by means of two techniques, Artemia salina, LD50 (4466 ± 1057 ppm, 630 ± 108 ppm, 1513 ± 797 ppm, 1585 ± 317 ppm, 1259 ± 242 ppm) and red cells, Haemolysis (1.58 ± 0.98%, 4.02 ± 2.03%, 8.42 ± 1.38%, 2.59 ± 2.31%, 2.92 ± 0.52%), to provide preliminary information that can be used as a basis for further studies to contribute to the search for new antioxidants.
  • Miniatura
    Ítem
    SOLUBILIZATION OF P-ALKYLPHENOLS IN PLURONICS F-68 AND F-127 MICELLES: PARTITION COEFFICIENTS AND EFFECT OF SOLUTE ON THE AGGREGATE STRUCTURE
    (Sociedad Chilena de Química, 2014-07) OLEA, ANDRÉS F.; CARRASCO, HÉCTOR; ESPINOZA, LUIS; ACEVEDO, BETSABE
    The partition of a series of substituted phenols between water and polymer micelles formed by Pluronic F-68 and F-127 has been studied. The formation of micelles by these block copolymers has been evidenced by steady-state fluorescence and dynamic light scattering. The data show that micelles and larger aggregates are formed above the critical micelle concentration. In presence of p-alkylphenols a micelle rearrangement occurs that leads to the formation of just one and large aggregate. This effect depends both on polymer and phenols structures. The partition coefficients and the standard free energies of transfer from the aqueous to the micellar phases were determined. The incremental free energy for a methylene group are 2.88 kJ mol-1 and 1.65 kJ mol-1 for F-127 and F-68, respectively. This difference is explained in terms of the core sizes that are determined by the length of the PPO block.