Browsing by Author "Asencio, M"

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    Antioxidant activity of crude extract, alkaloid fraction, and flavonoid fraction from boldo (Peumus boldus Molina) leaves
    (2004) Quezada, N; Asencio, M; del Valle, JM; Aguilera, JM; Gómez, B
    Boldo is an endemic plant from Chile widely used in folk medicine, whose biological (mainly antioxidant) activity has been attributed to the presence of the alkaloid boldine. The aim of this study was to determine the contribution of the flavonoid and other crude fractions from boldo leaves to the antioxidant activity of extracts. The main constituent in the flavonoid fraction was also isolated. The antioxidant activity and reducing power of crude boldo extract and fractions were measured and compared with natural and synthetic antioxidants. The antioxidant activity of boldo leaf extracts came mainly from the flavonoid fraction (44.1%) followed by the alkaloid fraction (15.6%), with catechin and boldine being the main contributors of the antioxidant activity of these 2 fractions (60.9% and 35.6% of the total activity, respectively). On the basis of these results, we propose to use catechin and boldline as markers for the antioxidant activity of boldo leaves. Tailor-made antioxidants to be used in foods can be prepared by enriching these 2 fractions.
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    Recovery of antioxidants from boldo (Peumus boldus M.) by conventional and supercritical CO2 extraction
    (2004) del Valle, JM; Godoy, C; Asencio, M; Aguilera, JM
    Boldo (Peumus boldus M.) is a native plant from Chile that has been used is traditional medicine to treat digestive and/or hepatobiliary disorders. An attempt was made in this work to extract antioxidant compounds from boldo using conventional solvents and supercritical carbon dioxide (SCCO2). Yield of soluble solids (SS), boldine, and compounds with antioxidant activity varied depending on part plant, solvent and extraction conditions. Following 24 h extraction, the highest yield was 33.4% (w/w, dry basis) of SS with 70:30 ethanol/water (v/v) mixture at 70 degreesC. Yield of alcoholic extractions increased as the temperature was raised from 20 to 70 degreesC, but the total antioxidant activity (free radical DPPH method) was maximal in boldo leaf extracts with aqueous ethanol at 50 degreesC (1648 TEAC/g dry leaf). Boldine concentration was maximal (12%) in boldo bark extracted with acidulated water, and decreased with extraction time when methanol or ethanol/water mixtures were used. No boldine was detected in boldo leaf extracts. The contribution of boldine to the antioxidant activity of boldo extracts was low, specially when using aqueous ethanol as solvent, and/or boldo leaf instead of boldo bark as substrate. Yield Of SCCO2 extraction was approximate to3% SS. Only non-polar compounds with limited antioxidant activity (0.08 TEAC/g extract) were extracted by SCCO2. (C) 2004 Elsevier Ltd. All rights reserved.