ABSTRACT The deciduous plant Copaifera langsdorffii contains important medicinal compounds which may also be allelopathic and inhibitory to plant growth. The species is endemic to the Brazilian Cerrado where there is pronounced climatic seasonality. In this study we demonstrate the allelopathic capacity of extracts from the leaves of C. langsdorffii and pre-purified fractions of the extract. Analysis by HPLC-PAD-ESI-MS confirmed the presence of quercetin-3-O-α-rhamnoside and kaempferol-3-O-α-rhamnoside as major components, as well as phenolic acid derivatives of gallic acid. The extracts from samples collected during the wet season were rich in flavonoids and reduced the seed germination rate, root emergence time, and root growth of Sorghum bicolor seedlings. Leaves of C. langsdorffii collected in both the wet and the dry season did not differ in the overall phytotoxic potential of their extracts, but differences detected in tested subfractions seem to indicate subtle seasonal changes in chemical composition. These results indicate that changes in the seasonal water status of the Cerrado induces differential synthesis of compounds with higher allelopathic activity.

A rapid analytical approach, suitable to characterize the compounds present in the aqueous and methanol extracts prepared from the aerial parts of Indigofera hirsute, was developed. The method based on high-performance liquid chromatography coupled to mass spectrometry, electrospray positive ionization and detection by time of flight (HPLC-ESI-MS-TOF) identified, tryptophan, uracil, rutin, kaempferol-3-O-β-D-glucopyranoside, gallic acid and methyl gallate. The antiradical activity of this extract was evaluated using DPPH assay, with gallic acid as antiradical pattern. The study revealed the antiradical activity of methyl galatte (EC50 = 5 ± 0.3 µg mL-1) galic acid (EC50 = 5 ± 0.2 µg mL-1) and rutin (EC50 = 21.6 ± 0.6 µg m L-1), isolated from methanol extract (EC50 = 67.7 ± 0.9 µg mL-1), which showed strong antiradical activity.

Um novo composto, isolado a partir do extrato metanólico das folhas de Paepalanthus argenteus var. argenteus (Bongard) Hensold foi caracterizado como xeractinol, um novo diidroflavonol C-glucosilado. Sua estrutura foi elucidada com base em extensiva análise espectroscópica (RMN uni- e bidimensionais, EM, HREIMS, IV, UV). Cálculos ab initio de estrutura eletrônica corroboram nossa proposição para a estrutura molecular. O diidroflavonol aqui isolado pode servir como marcador taxonômico de Paepalanthus subg. Xeractis, uma vez que este flavonóide não foi encontrado em nenhum outro taxon de Eriocaulaceae.

New compound isolated from methanolic extract from the leaves of Paepalanthus argenteus var. argenteus (Bongard) Hensold was characterized as xeractinol, a new dihydroflavonol C-glucoside. The structure was elucidated on the basis of extensive spectroscopic analysis (1D and 2D NMR, MS, HREIMS, IR and UV). Ab initio electronic structure calculations support our proposal to the molecular structure. The dihydroflavonol herein isolated may serve as taxonomic marker of Paepalanthus subgenus Xeractis, because this flavonoid have not been reported in any other taxon of Eriocaulaceae.

High-speed counter-current chromatography (HSCCC) is a major tool for the fast separation of natural products from plants. It was used for the preparative isolation of the flavonoid monoglucosides present in the aerial parts of the Davilla elliptica St. Hill. (Dilleniaceae). This species is used in Brazilian folk medicine for the treatment of gastric disorders. The optimum solvent system used was composed of a mixture of ethyl acetate-n-propanol-water (140:8:80, v/v/v) and led to a successful separation of quercetin-3-O-alpha-L-rhamnopyranoside and myricetin-3-O-alpha-L-rhamnopyranoside in approximately 3.0 hours with purity higher than 95%. Identification was performed by ¹H NMR, 13C NMR and HPLC-UV-DAD analyses.

Do extrato etanólico dos capítulos e dos escapos de Syngonanthus bisulcatus (Koern) Ruhland foram isolados os flavonóides: 5-hidroxi-7,4'-dimetoxi-6-C-beta-D-glicopiranosilflavona, isovitexina (5,7,4'-triidróxi-6-C-beta-D-glicopiranosilflavona, luteolina (5,7,3',4'- tetraidroxiflavona), lutonarina (5,3',4'-triidroxi-6-C-7-O-beta-D-glicopiranosilflavona) e 5,6,3',4'-tetraidroxi-7-O-beta-D-glicopiranosilflavona. As estruturas dos compostos foram caracterizadas por espectroscopia (RMN mono e bi-dimensionais) e por espectrometria de massas Electrospray. Adicionalmente foram examinados os efeitos dos extratos etanólicos dos capítulos e dos escapos pelo modelo de úlcera induzida por etanol/HCl

From the ethanol extract of the capitula and scapes of Syngonanthus bisulcatus (Koern) Ruhland the flavonoids 5-hydroxy-7,4'-dimethoxy-6-C-beta-D-glucopyranosylflavone, isovitexin (5,7,4'-trihydroxy-6-C-beta-D-glucopyranosylflavone), luteolin (5,7,3',4'-tetrahydroxyflavone), lutonarin (5,3',4'-trihydroxy-6-C-7-O-beta-D-glucopyranosylflavone) and 5,6,3',4'-tetrahydroxy-7-O-beta-D-glucopyrade were isolated. The structure of the compounds were characterized by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as ESMS spectrometry. In addition we examined the effect of the ethanol extract of capitulae and scapes in the ulcer model ethanol/HCl-induced gastric mucosal lesions.

Este trabalho apresenta o estudo de substâncias apolares obtidas a partir de plantas pertencentes ao gênero Paepalanthus Mart. (Eriocaulaceae). Hidrocarbonetos alifáticos de cadeias longas lineares foram identificados por CG-DIC e CG-EM. Os resultados indicam que as espécies de Paepalanthus subg. Platycaulon apresentam perfil homogêneo, com cadeias carbônicas de n-alcanos variando de C25 a C31, com a maioria das amostras apresentando freqüências maiores dos homólogos C27 e C29. As espécies do subgênero Paepalocephalus podem ser diferenciadas pela distribuição dos n-alcanos principais. P. macrocephalus, uma espécie da subseção Aphorocaulon, apresenta perfil com alcanos de cadeia ímpar, enquanto P. denudatus e P. polyanthus, espécies da seção Actinocephalus, apresentam perfil bem distinto, com grande número de cadeias mais curtas e alta freqüência de cadeias com número par de carbonos, especialmente P. polyanthus. Os resultados obtidos indicam que a distribuição de nalcanos pode ser útil como caráter taxonômico, assim como as substâncias mais polares, como os flavonóides glicosilados.

This work presents the study of nonpolar compounds from plants belonging to the genus Paepalanthus Mart. (Eriocaulaceae). Long-chain linear aliphatic hydrocarbons were identified by GC-FID and GC-MS. The results indicate that Paepalanthus subg. Platycaulon species present a very homogenous profile, with carbon chains of n-alkanes ranging from C25 to C31, most samples presenting higher frequencies of C27 and C29 homologues. Paepalanthus subg. Paepalocephalus species may be distinguished from one another by the distribution of main n-alkanes. P. macrocephalus, subsect. Aphorocaulon species, presents alkanes with odd-carbon numbers and P. denudatus and P. polyanthus, Actinocephalus species, present alkanes with quite distinctive profiles, with many shorter chains and a high frequency of even-carbon number, especially P. polyanthus. The results obtained indicate that the distribution of alkanes can be a useful taxonomic character, as do polar compounds like flavonoid glycosides.

Do extrato etanólico dos capítulos de Paepalanthus microphyllus, isolou-se um derivado do ácido cafeico (1). Sua estrutura foi caracterizada por métodos espectroscópicos (RMN mono e bi-dimensionais) e por espetrometria de massas Electrospray. Foram, também, isolados outros três flavonóides (2-4) de interesse taxonômico, os quais foram identificados por métodos espectroscópicos e comparados com dados da literatura.

From the ethanolic extract of the capitulae of Paepalanthus microphyllus, one caffeic acid derivative (1) was isolated. The structure of the compound was characterized by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as ESMS spectrometry. In addition, three flavonoids of taxonomic relevance were isolated and identified by comparison to literature data.