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 ...

A new compound, 5,7,3'-trihydroxy-4'-methoxy-8-prenylisoflavone, was isolated from the leaves of Vatairea guianensis Aubl. (Fabaceae), together with two known isoflavones lupiwighteone and 5,7,4'-trihydroxy-3'-methoxy-8-prenylisoflavone. All isolated compounds were characterized based on infrared (IR), UV, 1 H and 13 C nuclear magnetic resonance (NMR), including 2D NMR analyses and high resolution mass spectrometry. The ethanolic extract from V. guianensis leaves displayed activity against Candida dubliniensis, C. albicans and C. krusei. However, the EtOAc fraction from that extract exhibited more significant activity than the ethanolic extract, showing antifungal activity for all fungi species investigated. The major compound 5,7,3'-trihydroxy-4'-methoxy-8-prenylisoflavone isolated from that EtOAc fraction was also active against C. parapsilosis and C. dubliniensis.

A biodiversidade Amazônica pode ser uma fonte de substâncias capazes de serem utilizadas no controle de plantas daninhas. Neste estudo relatamos o isolamento e a identificação de cinco estilbenos a partir das folhas do "timbó vermelho" (Deguelia rufescens var. urucu): 4-metoxilonchocarpeno (1); 3,5-dimetoxi-4′-hidroxi-3′-prenil-trans-estilbeno (2), lonchocarpeno (3), 3,5-dimetoxi-4′-O-prenil-trans-estilbeno (4) e pteroestilbeno (5). As substâncias 2 e 4 são novos produtos naturais, porém 2 já havia sido citada como produto de síntese. Foi avaliada a potencial atividade alelopática de 1, 2 e 4 sobre a germinação de sementes e o crescimento da planta daninha Mimosa pudica. Os efeitos observados sobre a germinação das sementes de M. pudica não variaram significantemente (p > 0,05) quando a análise da fitotoxidade foi realizada com as substâncias isoladamente, cuja inibição máxima não ultrapassou 20%. A inibição mais intensa, quanto ao desenvolvimento da radícula e do hipocótilo, foi encontrada para o composto 4 (p < 0,05). Isoladamente, 4 causou efeito inibitório significativamente maior (p < 0,05) no desenvolvimento da radícula e do hipocótilo, do que 1 e 2. Quando testados aos pares, apresentaram antagonismo para a germinação de sementes e sinergismo para o desenvolvimento da radícula e hipocótilo.The Amazon biodiversity may provide plants whose chemical substances are capable of controlling weeds. In this study we report the isolation and identification of five stilbenes from the leaves of "timbó vermelho" (Deguelia rufescens var. urucu): 4-methoxylonchocarpene (1); 3,5-dimethoxy-4′-hydroxy-3′-prenyl-trans-stilbene (2), lonchocarpene (3), 3,5-dimethoxy-4′-Oprenyl-trans-stilbene (4) and pterostilbene (5). Compounds 2 and 4 are new natural products although 2 has been previously cited as synthesis product. Potential allelopathic activity for 1, 2 and 4 was evaluated over seed germination and plant growth of Mimosa pudica weed. The observed effects on seed germination did not vary significantly (p > 0.05) when the analysis of phytotoxicity was performed with the substances alone, the maximum inhibition did not exceed 20%. The most intense inhibitions on radicle and hypocotyl development were found for compound 4 (p < 0.05). When tested in pairs, showed antagonism for seed germination and synergism for radicle and hypocotyl development.

The chemical study of ethanol extract of sapwood of Vatairea guianensis Aubl. resulted in the isolation and structural identification of two compounds not previously described in the literature for the species, namely bolusanthol D and formononetin. In addition, other common compounds were identified, such as physcion, chrysophanol, betulinic acid, sitosterol and stigmasterol. The structural elucidation of substances was performed by spectroscopic data of 1 H and 13 C NMR and bidimensional techniques and comparison with the literature data. The ethanol extract of sapwood showed a significant antioxidant activity (EC 50 = 3.7 ± 0.3 µg mL-1) by DPPH radical scavenging method in comparison to Trolox (EC 50 = 4.5 ± 0.1 µg mL-1). This work is the first describing on chemical studies and antioxidant potential of the sapwood to V. guianensis.