Dihydroflavonols from the leaves of Derris urucu (Leguminosae): structural elucidation and DPPH radical-scavenging activity

Abstract

Derris urucu é uma planta da Amazônia com propriedades inseticida e ictiotóxica. Estudos com esta espécie reportam a presença de flavonóides, principalmente rotenóides, bem como de estilbenos. A partir do extrato etanólico das folhas de Derris urucu (Leguminosae), três novos diidroflavonóides, denominados urucuol A (1), B (2) e C (3) e o diidroflavonol isotirumalina (4), foram isolados e identificados. As estruturas destes compostos foram elucidadas por uma extensiva análise espectroscópica de RMN uni e bidimensional, UV, IV e dados de EM, além de comparação com dados da literatura. Os compostos isolados (1-4) foram avaliados quanto ao seu potencial sequestrador do radical DPPH • e apresentaram baixo poder antioxidante quando comparados ao antioxidante comercial trans-resveratrol.Derris urucu is an Amazonian plant with insecticide and ichthyotoxic properties. Studies with this species show the presence of flavonoids, mainly rotenoids, as well as stilbenes. The ethanol extract of the leaves of Derris urucu (Leguminosae) afforded three new dihydroflavonols named urucuol A (1), B (2) and C (3), and the dihydroflavonol isotirumalin (4). Their structures were elucidated by extensive analysis of 1D and 2D NMR, UV and IR spectra and MS data and comparison with literature data. The isolated compounds (1-4) were evaluated for DPPH • radical scavenging activity and showed a relatively lower antioxidant ability compared to the commercial antioxidant trans-resveratrol. Keywords: Derris urucu, Leguminosae, dihydroflavonols, radical scavenging activity, antioxidant IntroductionAmazonian ecosystems are rich in plants with insecticide and piscicide properties, and those belonging to the Derris genus are the most used. 1 These plants, in the Amazon area, are called "timbó". Some studies carried out on roots of Derris urucu extracts related the presence of rotenoids, especially rotenone, that show insecticide and ichthyotoxic activity. [2][3][4][5] In addition to rotenoids, others minor flavonoids, such as flavanones, isoflavanones and chalcones, together with stilbenes, have been also described from the roots of Derris urucu. 6 Flavonoids belong to a group of naturally occurring compounds with a number of biological activities, such as antibacterial, antimutagenic, cytotoxic and anticarcinogenic, 7-10 together with antioxidant activity, which is one of the most studied. 11,12 Antioxidant activity arises from the ability of flavonoids to scavenge free radicals and thus eliminate reactive oxygen species. 13,14 These phenolic compounds are known to possess an antioxidant character to various extents. [15][16][17] Therefore, the antioxidant activity of these natural compounds is related to a number of different mechanisms such as free radical scavenging, hydrogen donation, singlet oxygen quenching, metal ion chelation, and acting as a substrate for radicals such as superoxide and hydroxide. 18 Because oxidative stress is known to cause many diseases, scientists have become more interested in natural sources to fight it, looking for ...

Design and Evaluation of 4‐Aminophenol and Salicylate Derivatives as Free‐Radical Scavenger

“…All molecules were evaluated on the 100 lM concentrations based on the equimolecular reaction between DPPH and test compounds, modified from a method previously reported (20,21). All molecules were evaluated on the 100 lM concentrations based on the equimolecular reaction between DPPH and test compounds, modified from a method previously reported (20,21).…”

“…The percent scavenging activity was calculated using the formula: DPPH Equimolecular Inhibition (DPPH EI% ) = 100 · (Abs compound ) ⁄ (Abs ethanol ) (13,14,20). The measurements were recorded at delays of 20 min.…”

“…All tests were repeated three times, and the values for the absorbance (in arbitrary units) were averaged. The percent scavenging activity was calculated using the formula: DPPH Equimolecular Inhibition (DPPH EI% ) = 100 · (Abs compound ) ⁄ (Abs ethanol ) (13,14,20). This assay is based on the equimolecular reaction between DPPH and test compounds introduced for us.…”

“…In this study, we have used fast and economical methods for measuring the radical scavenging effects using equimolecular reactions between DPPH and the test compounds. All molecules were evaluated on the 100 lM concentrations based on the equimolecular reaction between DPPH and test compounds, modified from a method previously reported (20,21).…”

Inhibition ofα-Glucosidase and Hypoglycemic Effect of Stilbenes from the Amazonian PlantDeguelia rufescensvar.urucu(Ducke) A. M. G. Azevedo (Leguminosae)

“…urucu extracts reported the presence of rotenoids, which show insecticide and ichthyotoxic activity [13][14][15]. Additionally, flavonoids have also been described from the roots and leaves of this plant [16,17]. The biological activities of the stilbenes lonchocarpene and DPS are so far unknown.…”