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, 1H and 13C 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.

Das folhas de Vatairea guianensis Aublé foram isoladas quatro isoflavonas identificadas como, 5,3',-diidroxi-4'-metoxi-2",2"-dimetilpirano-(5",6":8,7)-isoflavona ( 1: ), 5,7-diidroxi-3',4'-metilenodioxi-8-prenil-isoflavona ( 2: ) e 5,3'-diidroxi-4'-metoxi-7-O-β-glicopiranosídeo-8-prenil-isoflavona ( 3: ) e derrona ( 4: ), juntamente com cinco triterpenos identificados em mistura de lupeol, α-amirina, β-amirina, germanicol e ácido betulínico. As substâncias 1: 3: são novos produtos naturais, porém 1: e 2: já foram citados como produtos de síntese. No entanto, todas essas substâncias são relatadas pela primeira vez para essa espécie. Suas estruturas químicas foram elucidadas com base nos seus dados de ressonância magnética nuclear (RMN) 1D e 2D e por espectrometria de massas de alta resolução. O extrato etanólico das folhas e os compostos 1-3: foram avaliados quanto ao seu potencial sequestrador do radical DPPH• (2,2-difenil-1-picril-hidrazila) e os resultados mostram que o extrato apresentou alta atividade (CI50 = 6,2 ± 0,4 µg mL-1), enquanto as substâncias testadas apresentaram baixo poder antioxidante (CI50 ≥ 29,5 ± 2,5 µg mL-1) quando comparadas com TROLOX (CI50 = 4,5 ± 0,4 µg mL-1).

Four isoflavones were isolated from Vatairea guianensis Aublé leaves and identified as 5,3'-dihydroxy-4'-methoxy-2",2"-dimethylpyrano-(5",6":8,7)-isoflavone ( 1: ), 5,7-dihydroxy-3',4'-methylenedioxy-8-prenyl-isoflavone ( 2: ), 5,3'-dihydroxy-4'-methoxy-7-O-β-glucopyranoside-8-prenyl-isoflavone ( 3: ) and derrone ( 4: ) together with five triterpenes identified in mixture, lupeol, α-amyrin, β-amyrin, germanicol and betulinic acid. Substances 1: 3: are novel natural products, although 1: and 2: have been cited as synthetic products. However, all these compounds are first reported from this species. Their chemical structures were elucidated based on their 1D and 2D nuclear magnetic resonance (NMR) data and high resolution mass spectrometry. The ethanol extract from the leaves and 1: 3: were evaluated for their potential in scavenging DPPH• (2,2-diphenyl-1-picrylhydrazylradical) and the results showed that the extract presented high activity (IC50 = 6.2 ± 0.4 µg mL-1), while the isolated compounds showed low antioxidant power (IC50 ≥ 29.5 ± 2.5 µg mL-1) when compared to Trolox (IC50 = 4.5 ± 0.4 µg mL-1).

Um novo derivado de antraquinona, denominado guepinone (1), juntamente com as conhecidas substâncias isossulocrina (2) e cloroissosulocrina (3) foram isolados de uma cultura em arroz de Pestalotiopsis guepinii, um fungo endofitico de Virola michelii. Os compostos foram identificados pela análise de seus dados espectrométricos de RMN 1D e 2D e EM. A atividade antimicrobiana dos compostos isolados foi avaliada e a cloroisossulcrina (3) foi a mais ativa.

A new anthraquinone derivative, named guepinone (1), along with the known substances isosulochrin (2) and chloroisosulochrin (3), were isolated from a rice culture of Pestalotiopsis guepinii, an endophytic fungus of Virola michelii. The compounds were identified by analysis of 1D and 2D NMR and MS spectral data. The antimicrobial activity of these compounds was evaluated and chloroisosulchrin (3) was the most active.

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.

Two compounds, (+)-catechin and epicatechin, were isolated from leaves of T. myrmecophyla, using chromatographic techniques. The structural identification was carried out on the basis of ¹H and 13C NMR spectral data and comparison with literature data. The compounds (+)-catechin and epicatechin were submitted to germination inhibition and radicle and hypocotyl growth assays. Results showed some significant activities confirming the initial hypothesis about allelopathic properties of that plant.