Papers by Felipe Medeiros
Fuel, 2015
h i g h l i g h t s Simple sulfonation of biodiesel waste cake in mild conditions produces a new ... more h i g h l i g h t s Simple sulfonation of biodiesel waste cake in mild conditions produces a new and active heterogeneous acid catalyst. The catalytic activity is comparable to H 2 SO 4 and the catalyst can be reused several times. The catalyst combines a carbon-sulfonic acid surface with a very hydrophilic cellulose surface responsible for water removal.
Applied Magnetic Resonance, 2014
ABSTRACT Annona muricata is a medicinal plant where acetogenins have been reported to contribute ... more ABSTRACT Annona muricata is a medicinal plant where acetogenins have been reported to contribute to its biological activity. An experimental protocol was developed for the quantitative determination of total α,β-unsaturated-γ-lactone acetogenins content in its leaves. The comparison of the olefinic γ-lactone signal intensities of each kind of acetogenin to the intensity of the internal standard anthracene was used for quantification. This measuring process was able to establish the total α,β-unsaturated-γ-lactone acetogenins in the range from 3.38 to 15.05 mg g−1 depending on the investigated specimen. This method allowed a fast and simple quantification of acetogenins from A. muricata.
Natural Product Research, 2014
Annona crassiflora, a native tree from Brazilian Cerrado, is reported to possess several ethnomed... more Annona crassiflora, a native tree from Brazilian Cerrado, is reported to possess several ethnomedical uses. Here, we report the isolation and unambiguous characterisation of the flavonoids quercetin-3-O-β-D-glucopyranosil(1 → 6)-O-α-L-arabinoside (1), known as peltatoside, kaempferol-3-O-β-D-galactopyranoside (2), quercetin-3-O-β-D-galactopyranoside (3), quercetin-3-O-β-L-arabinopiranoside (4) and the ( - )-epicatechin (5) from the hydroalcoholic portion of the leaf ethanolic extract. Their structures were elucidated by using 1D and 2D NMR, ESI-MS, UV/Vis spectroscopy, optical rotation analysis and literature data comparison. The leaf ethanolic extract and its isolated compounds were evaluated by using antimicrobial, antioxidant and larvicidal assays, expressing antimicrobial and antioxidant activities. This is the first report on flavonoid isolation from A. crassiflora.
Natural Products and Bioprospecting, 2013
A quantitative 1 H NMR method (qHNMR) was used to measure the trigonelline content in the leaves ... more A quantitative 1 H NMR method (qHNMR) was used to measure the trigonelline content in the leaves of six species of the Annona genus. The methodology employed compared the intensities of the signals at δ 9.14 (H-2) and δ 0.00, the internal standard TSP-d 4. This measuring method was able to establish the concentration of trigonelline in the range from 0.67 to 10.04 mg•g-1 depending on the investigated extract.
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Papers by Felipe Medeiros