Browsing by Autor "Alessandra Braca"

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    Antioxidant Chalcone Glycosides and Flavanones from<i>Maclura</i>(<i>Chlorophora</i>)<i>t</i><i>inctoria</i>
    (American Chemical Society, 2003) Giuseppina Cioffi; Luis Morales Escobar; Alessandra Braca; Nunziatina De Tommasi
    Four chalcone glycosides (1-4), including three new natural products, and three flavanones (5-7) were isolated from the methanol extract of stem bark of Maclura tinctoria. The new compounds have been characterized as 4'-O-beta-D-(2' '-p-coumaroyl)glucopyranosyl-4,2',3'-trihydroxychalcone (1), 4'-O-beta-D-(2' '-p-coumaroyl-6' '-acetyl)glucopyranosyl-4,2',3'-trihydroxychalcone (2), and 3'-(3-methyl-2-butenyl)-4'-O-beta-D-glucopyranosyl-4,2'-dihydroxychalcone (3); the known derivatives were elucidated as 4'-O-beta-D-(2' '-acetyl-6' '-cinnamoyl)glucopyranosyl-4,2',3'-trihydroxychalcone (4), eriodictyol 7-O-beta-D-glucopyranoside (5), naringenin (6), and naringenin 4'-O-beta-D-glucopyranoside (7). Their structures were determined by 1D and 2D NMR and ESIMS. The antioxidant activity of all the isolated compounds was determined by measuring free-radical-scavenging effects using two different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay). The results showed that compound 3 was the most active in both antioxidant assays.
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    Triterpenes and anthraquinones from Picramnia sellowii Planchon in Hook (Simaroubaceae)
    (Elsevier BV, 2001) Luisa Balderrama; Alessandra Braca; Emilia García; Marcela Melgarejo; Cosimo Pìzza; Nunziatina De Tommasi