Navegando por Autor "Oldoni, Tatiane Luiza Cadorin"

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    Bioassay - guided isolation of proanthocyanidins with antioxidant activity from peanut (Arachis hypogaea) skin by combination of chromatography techniques.
    (2016) Oldoni, Tatiane Luiza Cadorin; Melo, Priscilla Siqueira; Massarioli, Adna Prado; Moreno, Ivani Aparecida Marchetto; Bezerra, Rosangela Maria Neves; Rosalen, Pedro Luiz; Silva, Gil Valdo José da; Nascimento, Andréa Mendes do; Alencar, Severino Matias de
    Purification and bioassay-guided fractionation were employed to isolate proanthocyanidins with antioxidant activity from peanut skin (Arachis hypogaea Runner 886). The crude extract was prepared with acetone (60% v/v) and purified using chromatographic methods, including a semipreparative HPLC technique. As a result, two proanthocyanidins were isolated and identified using NMR, epicatechin-(2 b?O?7, 4 b?8)-catechin (proanthocyanidin A1) and epicatechin-(b?2 O?7, 4 b?8)-epicatechin (proanthocyanidin A2). Despite the structural similarity, differences were observed in their antioxidant activity. Proanthocyanidin A1 proved to be more active, with EC50 value for DPPH radical scavenging of 18.25 lg/mL and reduction of Fe3+–TPTZ complex of 7.59 mmol/g, higher than that of synthetic antioxidant BHT. This compound evaluated by ABTS+_ was similar to that of natural quercetin. Therefore, peanut skin is an important source of bioactive compounds that may be used as a mild antioxidant for food preservation.
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    Isolation and analysis of bioactive isoflavonoids and chalcone from a new type of Brazilian propolis.
    (2011) Oldoni, Tatiane Luiza Cadorin; Cabral, Ingridy Simone Ribeiro; d’Arce, Marisa Aparecida Bismara Regitano; Rosalen, Pedro Luiz; Ikegaki, Masaharu; Nascimento, Andréa Mendes do; Alencar, Severino Matias de
    Activity-directed fractionation and purification processes were employed to identify isoflavonoids with antioxidant and antimicrobial activities from Brazilian red propolis. Crude propolis was extracted with ethanol (80%, v/v) and fractioned by liquid–liquid extraction technique using hexane and chloroform. Since chloroform fraction showed strong antioxidant and antimicrobial activities it was purified and isolated using various chromatographic techniques. Comparing our spectral data (UV, NMR, and mass spectrometry) with values found in the literature, we identified two bioactiveisoflavonoids (vestitol and neovestitol), together with one chalcone (isoliquiritigenin). Vestitol presented higher antioxidant activity against β-carotene consumption than neovestitol. The antimicrobial activity of these three compounds against Staphylococcus aureus, Streptococcus mutans, and Actinomyces naeslundii was evaluated and we concluded that isoliquiritigenin was the most active one with lower MIC, ranging from 15.6 to 62.5 μg/mL. Our results showed that Brazilian red propolis has biologically active isoflavonoids that may be used as a mild antioxidant and antimicrobial for food preservation.